ADSA Foundation Scholar Award. Biology of dairy cows during the transition period: the final frontier?

Estrogen-Driven Maintenance of GLUT1/GLUT4/SGLT1 under glucose starvation drives energy homeostasis in bovine PMNs

The negative energy balance (NEB) and fluctuations in estrogen (17β-estradiol, E2) during the perinatal period alter glucose metabolism in bovine polymorphonuclear neutrophils (PMN) by affecting the activity of glucose transporters. In the peripheral blood, glucose uptake by PMNs is primarily dependent on the Glucose transporter type1 (GLUT1), Glucose transporter type4 (GLUT4), and Sodium-glucose cotransporter1 (SGLT1). However, the mechanisms through which E2 regulates energy metabolism in these cells, particularly through the modulation of glucose transporter activity, are currently unclear. This study aimed to explore the regulatory mechanisms underlying the effect of E2 on the homeostasis of glucose metabolism in PMNs. The results revealed that E2 enhances the expression of GLUT1, GLUT4, and SGLT1 (P < 0.05) and increases hexokinase (HK) activity (P < 0.05) in PMNs. Additionally, E2 was found to inhibit Glycogen synthase kinase-3β (GSK-3β) activity (P < 0.05), increase glycogen and ATP levels (P < 0.05), and reduce apoptosis in PMNs. When PMNs were treated with 5 μM STF-31 (GLUT1 inhibitor) or 50 μM Phlorizin (SGLT2 inhibitor), their GSK-3β activity was significantly increased (P < 0.05). Further analysis indicated that E2 helps maintain cellular glycogen and ATP homeostasis in PMNs by regulating the competitive interactions among GLUT1, GLUT4, and SGLT1. Additionally, when cells were treated with 100 μM AF-1890 (HK inhibitor), the expression of GLUT1, GLUT4, and SGLT1 was significantly reduced (P < 0.05). However, E2 mitigated the inhibitory effect of AF-1890 on HK activity and reduced its influence on intracellular energy levels by promoting the expression of GLUT1, GLUT4, and SGLT1. This study demonstrates that E2 positively regulates the expression of GLUT1, GLUT4 and SGLT1 in PMNs, facilitating glucose uptake under low-glucose conditions. E2 also negatively regulates GSK-3β activity increasing cellular glycogen and ATP levels and thus maintaining energy homeostasis in these cells.

Colostrum Quality as an Indicator of the Immune Status of Cows and Its Association with Peripartum Disease Risk in a Grazing Dairy Herd

This study aimed to evaluate the association between colostrum quality, as indicative of the immune status of the cows, and peripartum disease risk occurrence in a herd of grazing dairy cows. A prospective cohort study was conducted on a grazing dairy farm with 3000 Holstein milking cows from 15 March 2022 to 15 March 2023. Multivariable binary logistic models evaluated the association between colostrum quality (expressed in Brix grades as a continuous predictor) and the risk of peripartum diseases (including dystocia, stillbirth, retention of fetal membranes, metritis, and clinical endometritis). We found that colostrum quality was negatively associated with the risk of dystocia (p = 0.02), stillbirth (p < 0.01), clinical endometritis (p = 0.02), and total peripartum diseases (p < 0.01). Conversely, colostrum quality was not related to the risk of retention of the placenta (p = 0.25) or metritis (p = 0.76). Additionally, we found that the calving season affected colostrum quality (p < 0.01). Conversely, parity number, dry period length, and milk yield in previous lactation did not affect it (p > 0.10). We concluded that colostrum quality, expressed in Brix grades, is negatively associated with peripartum disease risk in dairy cows and could be a useful indicator of the immune status of the cow.

Animal health and nutrition: metabolic disorders in cattle and improvement strategies

The health and productivity of cattle are significantly compromised by metabolic diseases on a global scale. These disorders disrupt normal metabolic processes, leading to substantial economic losses for the livestock industry. Metabolic disorders can arise from defective biochemical pathways, deficiencies in enzymes, coenzymes, or cofactors, and may be either inherited or acquired. Dairy cows are particularly susceptible during the transition period from late lactation to early management, facing conditions such as ketosis, milk fever, and hepatic lipidosis. This susceptibility is primarily due to reduced dry matter intake caused by fetal development and a decline in rumen capacity. The negative energy balance (NEB) during this phase, characterized by elevated blood concentrations of non-esterified fatty acids (NEFAs) due to increased energy mobilization, is closely linked to the onset of these diseases. Providing high-energy-density diets during this period is critical to mitigating the effects of NEB. Metabolic disorders represent a major health challenge in cattle, adversely affecting animal welfare and agricultural output. A comprehensive understanding of their etiology, clinical manifestations, diagnostic approaches, and management strategies is essential for effective prevention and treatment. Ongoing research and the adoption of preventive measures are vital to reducing the economic and health impacts of these diseases. Early diagnosis and proactive management strategies are crucial to mitigating their impact on dairy cattle health and productivity. Early identification enables timely interventions, preventing disease progression and reducing adverse effects on animal health. Proactive measures, such as optimizing nutritional programs, implementing precision farming technologies, and ensuring timely veterinary care, are essential for enhancing the overall wellbeing of dairy cows. This review serves as a valuable resource for veterinarians, researchers, and dairy farmers, offering in-depth insights into the etiology, clinical signs, diagnostics, and management of prevalent metabolic disorders in dairy cattle. By equipping stakeholders with this knowledge, it aims to support informed decision-making and improve herd management practices. The focus on early diagnosis and proactive strategies underscores the potential to significantly reduce the economic and health burdens imposed by metabolic diseases on the livestock industry.

Daily rhythms of glucose, insulin, and nonesterified fatty acid responses to an intravenous glucose tolerance test in dairy cows

In nonruminant species, glucose tolerance and insulin sensitivity are known to be regulated by circadian rhythms, which are repeating ~24-h cycles that govern many aspects of behavior, physiology, and metabolism. However, it is unknown if these rhythms exist in dairy cows. Our objective was to determine the fit of a daily rhythm of glucose, insulin, and nonesterified fatty acid (NEFA) clearance rates independent of daily patterns of nutrient intake. To accomplish our objective, 12 multiparous lactating Holstein cows were enrolled in a within-subject design conducted over 2 experimental periods (n = 6/period). Within each period, cows were subjected to intravenous glucose tolerance tests (IVGTT) at 4 timepoints, representing different times of the day (0300, 0900, 1500, and 2100 h). The 0900 and 2100 h IVGTT were performed 36 h apart, followed by a 7-d washout, and then the 1500 and 0300 h IVGTT were performed 36 h apart. Cows were fed 12 times/d at 2-h intervals beginning 24 h before the first IVGTT in each set until the second IVGTT in each set to stabilize feed intake across the day, with 1 time/d feeding occurring during the washout period. For each IVGTT, 250 g of glucose were infused as a 50% (wt/vol) d-glucose solution via a jugular catheter and blood was collected at -15, -5, immediately before, 0, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min relative to infusion. A mixed linear model with the fixed effects of cosine and sine and random effect of cow within period was used for the outcomes of clearance rate, half-life, baseline concentration, time to baseline concentration, and area under the curve (AUC) for glucose, insulin, and NEFA. A zero-amplitude test was used to determine the fit of a 24-h cosine function and cosinor rhythmometry was used to determine the amplitude and acrophase of the 24-h rhythm. Insulin concentrations at baseline followed a diurnal rhythm. Glucose and insulin clearance rate, half-life, and AUC also followed a diurnal rhythm. Glucose and insulin clearance rates peaked at 1247 h and 0944 h, respectively. No circadian rhythm was detected for plasma NEFA concentrations. Results suggest that insulin-stimulated glucose uptake is controlled differently throughout the day by circadian rhythms.

Changes in haematological and serum biochemical parameter concentrations from the day of calving to ketosis onset in Holstein dairy cows during the postpartum period

BACKGROUND

Dairy cows commonly experience a negative energy balance (NEB) during early lactation as energy demands for maintenance and milk production exceed intake. Although most cows metabolically adapt to NEB and avoid ketosis, those that fail to adapt develop ketosis, which disrupts metabolism and reduces productivity. Haematological and serum biochemical parameters are crucial for understanding these metabolic disruptions. However, limited research has examined how these parameters change from calving to ketosis onset. This study aimed to investigate these changes, identify parameters associated with ketosis classification, and evaluate their implications for dairy cow health. Blood samples were collected from the jugular vein of Holstein cows and β-hydroxybutyrate (BHBA) was tested once every three days during the postpartum period (8 times in 21 days).

RESULTS

Cows were categorised into three groups based on their highest BHBA concentration: non-ketosis (NK; BHBA < 1.2 mmol/L; n = 75), subclinical ketosis (SCK; BHBA ≥ 1.2 mmol/L and < 3.0 mmol/L; n = 46), and clinical ketosis (CK; BHBA ≥ 3.0 mmol/L; n = 35). The NK group had the highest red blood cell and monocyte counts, red cell distribution width, and alanine transaminase (ALT) concentrations. However, this group had the lowest mean corpuscular volume, mean corpuscular haemoglobin, non-esterified fatty acid (NEFA), and total bilirubin concentrations on the day of calving and at ketosis onset, followed by the SCK and CK groups (p < 0.05). In the NK group, counts of neutrophils, monocytes, and eosinophils, along with NEFA and lactate dehydrogenase (LDH) concentrations, decreased from the day of calving to ketosis onset. Conversely, ALT, aspartate transaminase (AST), and magnesium concentrations increased in the SCK and CK groups (p < 0.05). The NK group had the most pronounced changes in glucose, triglyceride, and magnesium and the lowest BHBA, LDH, and AST concentrations, followed by the SCK and CK groups (p < 0.05).

CONCLUSIONS

This study identified key haematological and serum biochemical changes associated with ketosis classification in dairy cows, highlighting metabolic adaptations in the NK group that mitigate ketosis risk and metabolic dysfunctions in the SCK and CK groups that develop ketosis. These findings provide practical markers for early detection and management of ketosis, supporting improved dairy cow health and productivity.

Insights into the Regulatory Effect of Danggui Buxue Tang in Postpartum Dairy Cows Through an Integrated Analysis of Multi-Omics and Network Analysis

Postpartum dairy cows often face significant challenges due to metabolic disorders. Danggui Buxue Tang (DBT), a botanical drug composed of Astragali radix and Angelica sinensis radix in a 5:1 ratio, has been recognized for its potential to alleviate metabolic disorders. Its regulatory mechanisms on livestock metabolic health have remained unexplored. This study integrated the analyses of serum pharmacochemistry, network pharmacology, serum metabolomics, and fecal microbiota to investigate the regulatory effects of DBT on metabolic adaptation in postpartum dairy cows. Following the oral administration of DBT, levels of blood non-esterified fatty acids and beta-hydroxybutyrate were decreased in multiparous dairy cows one week after calving. Five absorbed prototype metabolites of DBT were identified, specifically formononetin and nicotinic acid, both of which play roles in the regulation of lipid metabolic homeostasis. Furthermore, DBT modified the composition of the gut microbial community and glycerophospholipid levels. Decreases in serum phosphatidylethanolamine and phosphatidylcholine levels were closely correlated with the relative abundance of Bacillus and the concentration of circulating beta-hydroxybutyrate. These findings suggest that DBT contributes positively to metabolic health in postpartum dairy cows by regulating the gut microbiota and glycerophospholipid metabolism, providing new insights into strategies for promoting metabolic adaptation in dairy cows.

Dietary supplementation of S cutellariae radix flavonoid extract improves lactation performance in dairy cows by regulating gastrointestinal microbes, antioxidant capacity and immune function

Scutellariae radix flavonoid extract (SFE) has been acknowledged for its antioxidant, anti-inflammatory and antimicrobial properties in enhancing gastrointestinal microbial communities and improving the host's immunity. Nevertheless, the impacts of dietary supplementation with SFE on the gastrointestinal microbes and host metabolism in dairy cows remain uncertain. Therefore, the aim of this study was to assess the effects of dietary supplementation with SFE on the lactation performance, gastrointestinal microbes, and plasma biochemical parameters of dairy cows. Six ruminally and duodenally cannulated multiparous dairy cows were used in a crossover design over 28-d periods that included a 21-d adaptation and a 7-d sample collection period. Cows were fed a basal diet (CON group) or a basal diet supplemented with SFE at 25 g/d (SFE group). SFE supplementation tended to increase milk yield (P = 0.067) and milk urea N concentration (P = 0.079), and decreased the milk somatic cell counts (SCC, P = 0.036). Cows in the SFE group had lower plasma aspartate aminotransferase (AST), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-1β concentrations compared with the CON (P < 0.05). Meanwhile, SFE supplementation increased butyrate concentration in the rumen (P = 0.044). The microbial structure of rumen and duodenum were affected by SFE supplementation (P = 0.009 and P = 0.031; respectively), resulting in enrichment of Butyrivibrio in both parts of the SFE cows (P = 0.034 and P = 0.029; respectively). However, microbial structure and composition of feces were not affected by SFE supplementation. Overall, our study indicated that dietary supplementation with SFE could enhance lactation performance and milk quality in dairy cows by improving the gastrointestinal inner environment and health status.

Effects of peripartal rumen-derived direct-fed microbial supplementation on lactation performance, metabolism, ruminal fermentation, and microbial abundance in dairy cows

The objective of this study was to evaluate the effects of a rumen-derived direct-fed microbial (DFM) product on performance, blood biomarkers, ruminal fermentation, and bacterial abundance in dairy cows during the transition period until 100 DIM. Fifty-six Holstein cows were enrolled in a randomized complete block design from -21 to 100 DIM. Cows were blocked based on expected calving date, parity, and previous lactation milk yield for multiparous cows or genetic merit for primiparous cows. At -21 DIM, cows were randomly assigned to either a basal control diet supplemented with 150 g/d ground corn (CON; n = 29) or the control diet supplemented with ground corn plus a rumen-derived DFM product (GF; n = 27, 150 g/d ground corn + 5g/d of Galaxis Frontier [Native Microbials, San Diego, CA]; Clostridium beijerinckii at 1.0 × 107 cfu; Pichia kudriavzevii at 1.0 × 108 cfu; Ruminococcus bovis at 1.0 × 108 cfu; Butyrivibrio fibrisolvens at 1.0 × 108 cfu) that was top-dressed once a day. All cows received the same basal close-up diet from -21 DIM until calving (1.56 Mcal/kg DM and 14.46% CP) and the same lactation diet from calving to 100 DIM (1.76 Mcal/kg DM and 15.69% CP). We collected blood samples to measure biomarkers of metabolism, inflammation, and oxidative stress, as well as rumen fluid via esophageal tubing for ammonia, VFA, and microbial abundance from a subset of multiparous cows (n = 12/treatment) at various time points from -22 to 100 DIM. Compared with CON, GF cows produced more milk (+4.1 kg/d) during the postfresh period (6-14 wk). However, GF cows tended to produce more milk (+2.9 kg/d) than CON during the entire trial (0-14 wk). Although DMI was not affected by treatment, GF cows had greater feed efficiency (+0.18, milk/DMI) in the postfresh period. Compared with CON, GF cows had lower blood plasma glucose and higher BHB. Blood biomarkers showed greater concentrations of ceruloplasmin, haptoglobin, and reactive oxygen metabolites (ROM) in GF cows compared with CON. Compared with CON, GF cows had greater ruminal molar proportions of butyrate and tended to have greater valerate and lower acetate. These changes in ruminal VFA were coupled with alterations in ruminal microbial abundance, where compared with CON, GF cows tended to have a greater abundance of lactate-utilizing species (Megasphaera elsdenii), but lower abundance of cellulose-utilizing species (Fibrobacter succinogenes). Although greater ROM was accompanied by a mild inflammatory condition in GF cows, this was not detrimental to milk yield and DMI. Overall, our results suggest that supplementing GF in the transition period until 100 DIM positively affects lactation performance.

The supply of branched-chain amino acids and branched-chain keto acids alter lipid metabolism, oxidative stress, and apoptosis in primary bovine hepatocytes

Fatty liver impairs liver function and reduces productivity in dairy cows. Our previous in vivo findings demonstrated that branched-chain amino acids (BCAA) or branched-chain ketoacid (BCKA) improved liver function and lactation performance in dairy cows; however, the underlying mechanisms remain unclear. This study aimed to assess the impact of BCAA or BCKA supplementation on intracellular triglyceride (TG) accumulation, lipid metabolism, antioxidant response, and apoptosis in hepatocytes. Treatments were: control (CON): customized medium with amino acids, volatile fatty acids, fatty acids (FA), glucose, choline, insulin, and albumin concentrations equal to circulating levels in cows 4d postpartum; BCAA: CON + 33% additional BCAA of plasma BCAA 4d postpartum; and BCKA: CON + 33% additional BCKA of plasma BCAA 4d postpartum. Compared to CON, BCAA and BCKA reduced intracellular TG concentration by 32% and 40%, respectively, after 72h. BCAA and BCKA enhanced the uptake of palmitic acid, but upregulated the expression of genes regulating FA oxidation. Although mitochondrial membrane potential was reduced, oxidative protein damage (protein carbonyl levels) was decreased in BCAA- and BCKA-treated hepatocytes without changes in mitochondrial copy number. Additionally, compared to CON, BCAA and BCKA decreased the expression of executioner caspases (caspase 3 and caspase 7) and reduced the portion of hepatocytes with activated caspase 3/7, suggesting reduced apoptosis. These findings suggest that BCAA or BCKA supplementation improves hepatocyte lipid metabolism, antioxidant defenses, and apoptosis regulation, potentially mitigating the adverse effects of fatty liver. These mechanisms likely underlie the previously observed improvements in liver function and lactation performance.

Pathological and molecular investigation of infectious bronchitis in broilers: analyzing the impact of biosecurity lapses

Introduction

Infectious Bronchitis (IB) is an acute, highly contagious disease of poultry that leads to significant economic losses in intensive production systems. Preventive biosecurity measures are essential to control its spread, particularly in broiler farms. This study aimed to investigate the relationship between IB outbreaks and biosecurity practices on a broiler farm.

Methods

The farm, housing 96,000 broilers, experienced increased mortality (over 11%) during two consecutive production cycles. Consequently, serological, pathological, molecular and biosecurity investigations were conducted.

Results

Despite a vaccination program using two types of live vaccines (Massachusetts serotype and serotype 793B), serological testing revealed elevated antibody titers against the IB virus, suggesting exposure to a wild viral strain. Necropsy revealed various lesions, including hemorrhagic tracheitis, pulmonary hyperemia, fibrinous pericarditis, splenomegaly, and ascites. Histopathological findings showed necrotic tracheitis, multifocal hepatitis, and purulent bronchopneumonia. By PCR IB viral RNA was detected in all 24 swabs and tissue samples. Biosecurity evaluation revealed significant deficiencies in both external and internal measures, including improper cross-contamination prevention, inadequate flock management, and insufficient vaccination strategies.

Discussion

These biosecurity deficiencies, coupled with the inadequate selection of vaccines not tailored to the prevalent serotypes in the local area, allowed for the introduction and spread of wild IB virus strains. This highlights the critical importance of robust, well-implemented biosecurity protocols in preventing IB on poultry farms.

Polar Metabolite Profiles Distinguish Between Early and Severe Sub-Maintenance Nutritional States of Wild Bighorn Sheep

Background: Understanding the metabolic adaptations of wild bighorn sheep (Ovis c. canadensis) to nutritional stress is crucial for their conservation. Methods: This study employed 1H nuclear magnetic resonance (NMR) metabolomics to investigate the biochemical responses of these animals to varying sub-maintenance nutritional states. Serum samples from 388 wild bighorn sheep collected between 2014 and 2017 from December (early sub-maintenance) through March (severe sub-maintenance) across Wyoming and Montana were analyzed. Multivariate statistics and machine learning analyses were employed to identify characteristic metabolic patterns and metabolic interactions between early and severe sub-maintenance nutritional states. Results: Significant differences were observed in the levels of 15 of the 49 quantified metabolites, including formate, thymine, glucose, choline, and others, pointing to disruptions in one-carbon, amino acid, and central carbon metabolic pathways. These metabolites may serve as indicators of critical physiological processes such as nutritional intake, immune function, energy metabolism, and protein catabolism, which are essential for understanding how wild bighorn sheep adapt to nutritional stress. Conclusions: This study has generated valuable insights into molecular networks underlying the metabolic resilience of wild bighorn sheep, highlighting the potential for using specific biochemical markers to evaluate nutritional and energetic states in free-ranging ungulates. These insights may help wildlife managers and ecologists compare populations across different times in seasonal cycles, providing information to assess the adequacy of seasonal ranges and support conservation efforts. This research strengthens our understanding of metabolic adaptations to environmental stressors in wild ruminants, offering a foundation for improving management practices to maintain healthy bighorn sheep populations.

Invited Review: Inflammation and Health in the Transition Period Influence Reproductive Function in Dairy Cows

In the early postpartum period, dairy cows undergo significant adaptations in Ca and lipid metabolism, immune function, and inflammatory processes. Concurrent exposure to endotoxins from the uterus, gastrointestinal tract, or mammary gland increases the risk of disease and reproductive problems. Metabolic and inflammatory imbalances during this phase can have both immediate and long-term effects on reproductive health. Associations between metabolic disorders and reproductive outcomes are often confounded by immune activation and systemic inflammation. However, optimal markers, thresholds, and durations for identifying maladaptation and predicting adverse health or reproductive outcomes remain unclear. This narrative review examines key physiological changes during the transition period, including hypocalcemia, lipid mobilization, immune activation, systemic inflammation, and uterine disease. We discuss how these events may affect the dominant follicle, corpus luteum, oocyte, and uterus, potentially leading to prolonged anovulation, reduced estrus expression, impaired response to synchronization protocols, lower progesterone concentrations, and compromised fertility. Understanding these mechanisms will support the development of strategies to monitor, prevent, and mitigate the impacts of transition-related maladaptation on reproductive performance. Such advancements can enhance the health and fertility of high-producing dairy cows.

Impact of Low Inclusion Rate of Olive Cake in Dairy Cow Rations on Uterine Health and Fertility Indices During Early Lactation

Olive cake was incorporated at a low inclusion rate (3.7%) into the rations of dairy cows through partial substitution of maize, and its effects on milk production, general health, and fertility traits were investigated. Multiparous purebred Holstein dairy cows (n = 148) were divided into two groups: a treated group (n = 86) and a control group (n = 62). The control ration (group C) was modified by replacing 1 kg of maize with an equal quantity of olive cake (group T). The experiment lasted from 60 days prepartum to 150 days postpartum. Electronic aids were utilized to quantify daily milk yield and detect estrus expression, while clinical and uterine examinations were performed weekly. Blood samples, uterine epithelial cells, and endometrial tissue samples were collected from a subgroup of healthy animals in both groups at specific time points. Blood samples were examined to determine the β-hydroxybutyric acid (BHBA), acute phase proteins (haptoglobin [Hpt] and serum amyloid A [SAA]), progesterone, and pregnancy-associated glycoproteins concentrations. Uterine epithelial cells were assessed for polymorphonuclear neutrophil (PMN) counts, and the expression of nine genes encoding inflammatory cytokines and immune system activation was analyzed in uterine biopsy tissue. No significant differences (p > 0.05) were observed between groups in milk yield, general morbidity, clinical endometritis, or conception rates. However, animals in group T came to estrus approximately 6 days earlier (p = 0.013) than those in group C; progesterone concentrations on day 7 of the subsequent cycle tended (p = 0.07) to be higher in group T. On day 21, BHBA concentrations were higher in group C than in group T (p < 0.05). Throughout the experiment, Hpt levels in group T were consistently lower (p < 0.001), while SAA was lower on day 7 compared to group C. From days 21 to 42 postpartum, there was a significant reduction in PMN numbers (group C p = 0.02; group T p < 0.0001), with a tendency for a greater reduction rate in group T (p = 0.08). Among the genes studied, a significant difference was revealed in the expression of the ILA1 gene, with strong correlations of gene expression in group C and weak to moderate correlations in group T. In conclusion, under the conditions of this experiment, the inclusion of olive cake into dairy cows' rations did not affect milk production but improved certain health and fertility parameters, making olive cake a suitable alternative feedstuff for high-producing animals.

The Positive Regulatory Effect of DBT on Lipid Metabolism in Postpartum Dairy Cows

BACKGROUND/OBJECTIVES

The transition from a non-lactating to a lactating state is a critical period for lipid metabolism in dairy cows. Danggui Buxue Tang (DBT), stimulating energy metabolism, ameliorates diseases related to lipid metabolism disorders and is expected to be an effective supplement for alleviating excessive lipid mobilisation in periparturient dairy cows. This study aimed to investigate the effects of supplemental DBT on serum biochemical indices, faecal microbial communities, and plasma metabolites in dairy cows.

METHODS

Thirty cows were randomly divided into three groups: H-DBT group, L-DBT group, and control group. DBT administration was started on the day of calving and continued once daily for seven days. Faecal and blood samples were collected on calving day, 7 days after calving, and 14 days after calving. The levels of serum biochemical indices were measured at three time points in the three groups using commercial kits. Cows in the H-DBT group and control group were selected for metabolome and 16S rRNA amplicon sequencing.

RESULTS

Our research shows that, in dairy cows 7 days postpartum, DBT significantly reduced serum 3-hydroxybutyric acid (BHB) concentrations and the number of cows with BHB concentrations ≥ 1 mmol/L. Additionally, DBT increased serum total cholesterol contents at both 7 and 14 days postpartum. Analysis of the microbiota community showed that DBT modulated the composition and structure of the hindgut microbiota. Metabolomic analysis revealed decreased plasma acetylcarnitine, 2-hydroxybutyric acid, and BHB levels 7 days postpartum, whereas the TCA cycle was enhanced. At 14 days postpartum, DBT altered the plasma bile acid profile, especially glycine-conjugated bile acids, including GCDCA, GUDCA, and GDCA. Correlation analyses showed that the relative abundances of Bacillus, Solibacillus, Dorea, and Romboutsia were strongly correlated with the differential metabolites, which is crucial for the beneficial effects of DBT.

CONCLUSIONS

DBT improves energy status and lipid metabolism in postpartum dairy cows by modulating hindgut microbiota and serum lipid metabolites.

Supplemental palmitic acid and chromium propionate impact production responses during the immediate postpartum in multiparous dairy cows

Forty-eight multiparous Holstein cows were used in a randomized complete block design and assigned to one of 4 treatments in a 2x2 factorial arrangement of treatments to determine the effects of supplemental palmitic acid (C16:0) and chromium (Cr) on production responses of early-lactation cows. During the fresh period (FR; 1-24 d in milk), cows were fed one of 4 treatments: (1) a diet containing no supplemental C16:0 or Cr (CON); (2) diet supplemented with an 85% C16:0-enriched supplement (PA); (3) diet supplemented with Cr-propionate (CR); and (4) diet supplemented with a C16:0-enriched supplement and Cr-propionate (PACR). The C16:0-enriched supplement was added at 1.5% of diet DM by replacing soyhulls in the C16:0-supplemented diets, and the Cr-propionate supplement (0.45 mg Cr/kg of diet DM) was administered through the vitamin and mineral mix. During the carryover period (CO; 25-56 d in milk), a common diet was offered to all cows to evaluate the carryover effects of the treatment diets. Palmitic acid and Cr supplementation interacted with time during the treatment period, with the supplemented diets increasing the yields of ECM, 3.5% FCM, and milk fat to a greater extent during the first 2 weeks of lactation compared with CON. By the third week of lactation, C16:0 supplemented diets also increased milk fat yield compared with CR. Additionally, C16:0 and Cr interacted with time in the treatment period to influence plasma insulin, nonesterified fatty acid (NEFA), and BHB. Overall, C16:0 supplementation increased the yields of milk fat, ECM and 3.5% FCM, and decreased milk protein content in the treatment period. Overall, Cr supplementation increased the yields of milk, milk protein, and milk lactose in the treatment period. Additionally, Cr supplementation interacted with time, increasing the yields of milk, milk protein, and milk lactose during the CO period. We did not observe treatment differences for DMI and plasma glucose during the FR period, and no treatment effects on BW, BW change and BCS change in FR or CO periods. In conclusion, C16:0 and Cr supplementation interacted during the early postpartum period to impact milk production responses compared with a non-supplemented diet. Feeding Cr during the immediate postpartum had a carryover effect, improving milk production responses after ceasing feeding the treatment diets.

Prepartum Vaccination Against Neonatal Calf Diarrhea and Its Effect on Mammary Health and Milk Yield of Dairy Cows: A Retrospective Study Addressing Non-Specific Effects of Vaccination

Prepartum vaccinations against neonatal calf diarrhea pathogens are administered in late pregnancy to provide passive immunity to calves through protective colostral antibodies. Potential non-specific effects of the vaccine on maternal innate immune responses and disease susceptibility during the sensitive transition period have not been addressed so far. In this retrospective study, data from 73,378 dairy cows on 20 farms in Germany were analyzed, using linear mixed-effects regression, quantile regression, and decision-tree-algorithms, to investigate the effects of prepartum vaccination on mammary health and milk yield by comparing non-vaccinated and vaccinated transition periods. Herd management-related factors were found to be most influential for mammary health and milk yield. Vaccinated cows were not significantly more likely to develop mastitis and did not have significantly different somatic cell counts and milk yields compared to non-vaccinated cows. Healthy primiparous cows with and without vaccination had similar energy-corrected milk yields. The study concludes that prepartum vaccination against calf diarrhea has no significant effects on mammary health and milk yield. Further research is recommended to investigate potential non-specific vaccine effects on other organ systems, infectious diseases, and production metrics of the dairy cow.

Resveratrol Alleviates NEFA-Induced Oxidative Damage in Bovine Mammary Epithelial Cells by Restoring Mitochondrial Function

In periparturient dairy cows, high non-esterified fatty acids (NEFAs) caused by a severe negative energy balance induce oxidative stress and metabolic dysfunction, which pose a severe challenge to the dairy industry. Resveratrol (RES) is a polyphenolic compound with antioxidant, anti-inflammatory and multiple other physiological effects. However, its effect on oxidative damage triggered by NEFAs in bovine mammary epithelial cells is rarely reported. This study aimed to investigate the antioxidant effects and underlying molecular mechanisms of RES in NEFA-challenged BMECs. The results showed that RES ameliorated NEFA-induced oxidative damage by upregulating antioxidant enzyme expression and reducing malondialdehyde (MDA) and reactive oxygen species (ROS). Furthermore, exogenous NEFAs resulted in a decrease in mitochondrial membrane potential (MMP), cellular adenosine triphosphate (ATP) production, energy metabolism (NAD+/NADH ratio), abnormal mitochondrial structure and an increase in apoptosis levels. RES treatment restored mitochondrial function in NEFA-stressed BMECs, as evidenced by the increase in MMP, ATP generation and NAD+/NADH ratio accompanying the decline in mitochondrial structural abnormalities and cell apoptosis. In addition, in vivo studies in a mouse model of oxidative damage induced by high-fat diet (HFD) demonstrated that RES alleviated oxidative damage (decreased MDA content) and mitochondrial dysfunction (decreased expression of Drp1 and Fis1 and increased levels of Mfn2, Cyt C mRNA and ATP production) in mammary gland tissue. Overall, these findings suggested that RES could alleviate NEFA-induced oxidative damage in BMECs by modulating mitochondrial function, thereby contributing to the prevention and treatment of oxidative damage in perinatal dairy cows with a negative energy balance.

Effects of including a palmitic acid-enriched supplement in low and high starch diets on milk production and energy partitioning of primiparous and multiparous dairy cows between mid and late-lactation

The aim of our study was to assess the effects of low or high-starch diets with or without palmitic acid (C16:0) supplementation on the yield of milk, milk components, and energy partitioning of primiparous and multiparous dairy cows between mid and late-lactation. Thirty-two Holstein cows, 12 primiparous ([mean ± SD] 163 ± 33 d in milk) and 20 multiparous ([mean ± SD] 179 ± 37 d in milk), were used in a split-plot Latin square design. Parity was considered the main plot, and within each plot, treatments were then randomly assigned in a replicated 4 × 4 Latin square with 21 d periods and balanced for carryover effects. Treatments were in a 2 × 2 factorial arrangement of dietary starch level and fatty acid (FA) supplementation as main factors. The starch factor comprised either low (LS; 16% of diet dry matter [DM]) or high (HS; 32% of diet DM) dietary starch. Dietary starch was altered by varying the proportion of ground corn, whole cottonseed, and soyhulls, with LS and HS diets containing ∼15 and 18% forage neutral detergent fiber (fNDF) and ∼37 and 25% neutral detergent fiber (NDF), respectively. The FA supplementation factor consisted of either control with no FA supplementation (CON) or a C16:0-enriched supplement at 1.5% of diet DM replacing soyhulls (PALM). Compared with LS, HS increased plasma insulin (0.20 μg/L) and energy partitioning to body reserves (2.04 percentage-units), tended to increase body condition score (BCS) and body weight (BW) change, and decreased dry matter intake (DMI; 1.10 kg/d), milk fat yield (0.04 kg/d) and milk urea nitrogen (MUN; 2.10 mg/dL). Compared with CON, PALM increased energy output to milk (1.10 Mcal/d), the yields of milk fat (0.10 kg/d), 3.5% fat-corrected milk (FCM; 1.90 kg/d) and energy corrected milk (ECM; 1.60 kg/d), and had no effect on BW-related variables. We observed a 3-way interaction between parity, starch, and FA supplementation affecting multiparous but not primiparous cows, where PALM increased plasma insulin concentration (0.14 μg/L) in LS but had the opposite effect in HS by tending to decrease insulin. Our results demonstrate important interactions between parity, starch levels, and FA supplementation. Overall, feeding a low-starch diet to mid and late-lactation dairy cows helped prevent excessive body condition and weight gain while increasing milk fat yield compared with a high-starch diet. Multiparous cows may benefit the most from a low-starch diet as multiparous cows seemed more prone to accumulating body reserves. Feeding a C16:0-enriched supplement increased milk fat yield and ECM without increasing weight gain, regardless of starch level or parity.

International Symposium on Ruminant Physiology: The immunometabolism of transition dairy cows from dry-off to early lactation: lights and shadows

The mismatch between the nutrient intake from the diet and the output by the mammary gland causes a negative energy balance in transition dairy cows, that, if excessive, can promote several metabolic disorders. Other relevant phenomena occur during transition, such as inflammation at calving and changes in immunocompetence, redox balance, and mineral metabolism. Despite the efforts, some aspects of the adaptive mechanisms observed in the transition period still need to be clarified. For instance, alterations of physiological responses even before the dry-off or during the dry period can affect the success of the whole transition period in certain cows. In this context, the mechanism regulating the inflammatory response around calving may play a pivotal role, as suggested by the variety of factors influencing it and its consequences, particularly feed intake depression, that can amplify and anticipate the negative energy balance. When this mechanism derails is still unclear, but detecting the triggers of diverted or abnormal physiological responses and where they stem (e.g., liver, rumen and gut epithelia, uterus, or mammary gland) will help to discover the weak points in the immune system and the possible ways of restoring it. Furthermore, the postpartum healthy cow appears to have an acute phase response at the liver level, despite a decrease in circulating proinflammatory cytokines. What is physiological and what is pathological in this context? To understand the latter, finding markers of an unsuccessful transition period that go beyond the energy deficit would be advisable. Future efforts should be dedicated to clarifying the causes of the acute phase response at calving, exploiting the potential of the system biology. Moreover, it would be helpful, for both basic and applied research, to define biomarkers associated with pathological responses (i.e., cytokines and acute phase proteins) and to introduce in the genetic selection phenotypes related to the ability of cows to adapt to the immunometabolic stress typical of the transition period.

Longitudinal characterization of the muscle metabolome in dairy cows during the transition from lactation cessation to lactation resumption

Skeletal muscle is vital in maintaining metabolic homeostasis and adapting to the physiological needs of pregnancy and lactation. Despite advancements in understanding metabolic changes in dairy cows around calving and early lactation, there are still gaps in our knowledge, especially concerning muscle metabolism and the changes associated with drying off. This study aimed to characterize the skeletal muscle metabolome in the context of the dietary and metabolic changes occurring during the transition from the cessation of lactation to the resumption of lactation in dairy cows. Twelve Holstein dairy cows housed in tiestalls were dried off 6 wk before the expected calving date. Cows were individually fed ad libitum TMR composed of grass silage, corn silage, and concentrate during lactation and of corn silage, barley straw, and concentrate during the dry period. The metabolome was characterized in skeletal muscle samples (M. longissimus dorsi) collected on wk -7 (9 d before dry-off), -5 (6 d after dry-off), and wk -1, and wk 1 relative to calving. The targeted metabolomics approach was conducted using the MxP Quant 500 kit (Biocrates Life Sciences AG) with liquid chromatography, flow injection, and electrospray ionization triple quadrupole mass spectrometry. Statistical analysis on the muscle metabolite data was performed using MetaboAnalyst 5.0, which allowed us to conduct various multivariate analyses such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), informative heat map generation, and hierarchical clustering. The statistical analysis revealed a clear separation between pregnancy (wk -7, -5, and -1) and postcalving (wk 1). Starting 5 wk before calving and continuing through the first week thereafter, the concentration of 3-methylhistidine (3-MH) in the muscle increased. This coincided with an increase in the concentrations of 11 AA (Phe, His, Tyr, Trp, Arg, Asn, Leu, Ile, Gly, Ser, and Thr) in the first week after calving, whereas Gln decreased. l-Arginine pathway metabolites (homoarginine, ornithine, citrulline, and asymmetric dimethylarginine), betaine, and sarcosine followed a similar pattern, increasing from wk -7 to -5, but decreasing from wk -1 to 1. The transition from pregnancy to lactation was associated with an increase in concentrations of the long-chain acylcarnitine species C16, C16:1, C18, and C18:1 in the muscle, whereas the concentrations of phosphatidylcholine and sphingomyelin in the muscle remained stable. The significant changes observed in the metabolome mainly concerned the AA and AA-related metabolites, indicating muscle protein breakdown in the first week after calving. The metabolites produced by the l-Arg pathway might contribute to regulating skeletal muscle mass and function in periparturient dairy cows. The elevated concentrations of long-chain acylcarnitine species in the muscle in the first week after calving suggest incomplete fatty acid oxidation, likely due to insufficient metabolic adaptation in response to the fatty acid load around the time of calving.

Oxidative Stress Biomarkers and Metabolic Parameters in Healthy Holstein Dairy Cows and Cows With Left Displacement Abomasum During the Transitional Period

BACKGROUND

During the transitional period, dairy cows experience oxidative stress and are more susceptible to diseases, including left displacement of the abomasum (LDA).

OBJECTIVES

This study aimed to compare oxidative stress biomarker levels in cows with LDA to those in healthy conditions and investigate the associations between predictive metabolites linked to LDA and oxidative stress biomarkers.

METHODS

In this case-control study, 400 healthy multiparous Holstein cows were matched for lactation number, milk production and calving date. Blood samples were collected at four time points: 21 and 7 days before, as well as 7 and 21 days after parturition from all animals. During the observation period, seven cows diagnosed with LDA in the main population, and seven healthy cows were randomly selected as controls for the comparison of oxidative stress, liver enzymes and metabolic parameters. Analysis of blood parameters utilized repeated measures ANOVA, and the degree of relationship between oxidative stress biomarkers and other measured parameters was assessed using Pearson correlations.

RESULTS

The LDA group exhibited significantly higher levels of urea, blood urea nitrogen (BUN), gamma-glutamyl transferase, glucose, cholesterol, triglyceride (TAG), β-hydroxybutyric acid (BHBA), aspartate aminotransferase (AST), sorbitol dehydrogenase, serum amyloid A (SAA), chloride, sodium, potassium, total antioxidant capacity (TAC) and malondialdehyde (MDA) compared to the control cows (p < 0.05). Positive correlations were observed among BUN, glucose, TB, AST, SAA, BHBA, TAG and MDA. Conversely, these parameters displayed negative correlations with TAC. Negative correlations were found among chloride, sodium, potassium, calcium, phosphorus and MDA, whereas positive correlations were observed with TAC.

CONCLUSIONS

These findings highlight the elevated level of oxidative stress and compromised antioxidant defence in cows with LDA and the intricate interplay among oxidative stress, metabolic parameters and liver enzymes.

Adipose tissue oxylipin profile changes with subclinical ketosis and depot in postpartum dairy cows

Lipolysis of adipose tissue is a natural occurrence during the periparturient period in dairy cows. However, when lipolysis rates exceed the capacity of other tissues to used nonesterified fatty acids, it may lead to the development of ketosis and other diseases. Additionally, PUFA can become oxidized into oxylipins, which modulate inflammation and metabolism. The objective of this work was to identify depot-specific differences on adipose tissue oxylipin profile in dairy cows with and without subclinical ketosis and assess the effects of oxylipins on adipocyte function in vitro. Subcutaneous adipose tissue from the flank (SAT) and visceral adipose tissue from the omentum (VAT) were collected through laparotomy from multiparous dairy cows (5-14 DIM) and grouped according to blood BHB into nonketotic (NK; n = 5; BHB ≤ 0.8 mmol/L) and subclinical ketotic (SCK; n = 5; BHB 1.4 and ≤ 2.6 mmol/L). A targeted lipidome capable of detecting a 154 oxylipins was performed in paired SAT and VAT samples from all animals. Data were analyzed using the PROC GLIMMIX procedure in SAS (v9.4, SAS Institute Inc., Cary, NC) for the effect of depot (SAT, VAT), ketosis status (SCK, NK), and their interaction (depot × ketosis status) on oxylipin abundance. The oxylipins thromboxane-B2 (TXB2), prostaglandin-A2 (PGA2), and 5-hydroxeicostretanoic acid (5-HETE) were selected from lipidomic data based on effects of ketosis status and depot-specificity to further investigate their effects on SAT and VAT adipocyte function. Lipidomic data revealed 50 oxylipins across both adipose tissue depots. SCK was associated with a decreased abundance of TXB2 and tended to associate with an increase in PGA2 and prostaglandin-E1 (PGE1). Additionally, PGE1, 15-keto-prostaglandin-E2, 13,14-dihydro-15-keto-prostaglandin-E2, 5-HETE, and 15-HETE were increased in SAT. Although VAT had a greater abundance of 9,10-dihydroxy-12Z-octadecenoic acid, 12,13-dihydroxy-9Z-octadecenoic acid, 9-oxo-10E,12Z,15Z-octadecatrienoic acid, and 13S-hydroxy-9Z,11E,15Z-octadecatrienoic acid (13[s]-HOTrE). In vitro, an average (AVG) dose of 5-HETE on VAT cells tended to increase proliferation at d 7 compared with the control, HGH dose of TXB2 tended to decrease lipid accumulation in SAT compared with control, and AVG dose of PGA2 on VAT cells tended to lower ROS compared with the control. Overall, postpartum dairy cows have depot-specific adipose tissue lipidomic profiles which are associated with changes in ketosis status.

Temporal patterns of liver and adipose lipase abundance across the periparturient period in multiparous Holstein dairy cows

Lipases such as patatin-like phospholipase domain-containing protein 3 (PNPLA3) exist in multiple tissue types. In subcutaneous adipose tissue, PNPLA3 was not altered during the periparturient period. Conversely, strong associations between liver PNPLA3 and liver triglyceride content peripartum were identified and confirmed to be causative using knockdown approaches in a primary bovine hepatocyte model. The objective of this research was to characterize adipose and hepatic lipase abundance, as well as abundance of hepatic transcription factors (TF) involved in adipose and liver tissue lipolysis to determine potential impact on bovine fatty liver development and recovery. Adipose and liver tissue biopsy samples were collected from -28 to +56 d relative to calving (DRTC) from multiparous Holstein dairy cows randomly assigned to either a control (CTL) or ketosis induction protocol (KIP) diet. Clinical ketosis (blood BHB ≥ 3.0 mM) was used as a cowside indicator of successful induction and was achieved in CTL (n = 2) and KIP (n = 12) cows. Both adipose and liver abhydrolase domain-containing protein 5 and adipose triglyceride lipase (ATGL) differed across DRTC, as did liver perilipin 1. Hepatic mature and immature carbohydrate response element binding protein, and sterol regulatory binding protein 1c, varied or tended to vary across DRTC × treatment. Neither adipose nor liver hormone sensitive lipase (HSL) were responsive to treatment or varied across DRTC, but adipose HSL was positively associated with nonesterified fatty acids at +1 DRTC. Adipose and liver ATGL was associated with liver triglycerides across all DRTC. Patterns of adipose HSL and ATGL abundance did not explain the increase in nonesterified fatty acids observed at +1 DRTC in this study. Future investigation of lipase abundance in other adipose tissue depots is still needed to better explain regulation during this time. Bovine fatty liver development and recovery appears to be contingent upon liver PNPLA3 abundance, rather than liver ATGL.

Shortening of the telomere length during the transition period of dairy cows in relation to biological stress

Telomere length (TL) is a recognized biomarker for ageing in multiple species. In dairy cattle, the transition period is considered a very stressful period. We hypothesized that TL shortens during this period. Holstein cows (n = 61) were followed during the transition period. Blood and milk samples were collected at - 7, 3, 6, 9, 21d relative to calving to determine concentrations of oxidative, energetic metabolic, and inflammatory markers. Average relative leukocyte TL was measured by a modified qPCR protocol 7d before and 21d after parturition. We confirmed TL attrition during the transition period (P = 0.02), as TL was 1.05 ± 0.229 (mean ± SD) before, and 0.97 ± 0.191 (mean ± SD) after parturition. Univariable analyses assessed associations between blood markers and TL shortening. Greater plasma oxidative parameters, including oxidized glutathione and glutathione peroxidase, were positively and negatively (respectively) associated with TL attrition. Higher blood α- and β-globulin were all positively associated, while IGF-1, albumin-globulin ratio and albumin were negatively associated with TL attrition. Greater serum amyloid A and haptoglobin were linked with greater TL shortening. This study reveals significant TL shortening during the transition period in dairy cows and identifies significant associations with oxidative stress, metabolic stress, and inflammation. While these associations are observed, no causality can be established. Our findings suggest the need for further research to explore the effects of transition-related stress on TL dynamics.

Dietary Capsaicin Supplementation Mitigates Calving-Induced Stress and Enhances Antioxidant Capacity, Immune Function, and Gut Microbiota in Periparturient Dairy Cows

This study investigated the effects of dietary capsaicin supplementation on antioxidant capacity, immune function, and gut microbiota in periparturient dairy cows. Twenty Holstein cows with an average parity of 2.5 ± 0.76, milk production of 31.30 ± 2.39 kg, and 36.10 ± 2.38 days to calving were randomly assigned to either a control group fed a basal diet or a treatment group supplemented with 1.2 g/head/day of capsaicin. The supplementation was administered during an evaluation period spanning from 28 days before delivery to 21 days after delivery using a randomized block experimental design. Results showed that capsaicin significantly reduced milk somatic cell count and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) while enhancing serum antioxidant enzymes (SOD, GSH-Px, and CAT) and immunoglobulin levels (IgG, IgA, and IgM). Moreover, capsaicin altered gut microbiota composition, increasing the relative abundance of beneficial genera. These findings suggest that dietary capsaicin supplementation during the transition period improves lactation performance and supports immune function, as well as alleviates oxidative stress. This study highlights the potential of capsaicin as a practical dietary strategy for enhancing productivity in dairy farming.

Effects of Supranutritional Selenium Supplementation During Different Trimesters of Pregnancy on Humoral Immunity in Beef Cattle at Parturition

Supranutritional Se supplementation may improve immune responses in beef cattle. Immunity is compromised in beef cattle during the periparturient period. This study aims to determine the best time during pregnancy to supplement beef cows with Se-yeast to optimize humoral immunity at parturition. Multiparous, black Angus and Angus cross cows (n = 79) were used in the study. All cows had ad libitum access to a mineral supplement containing 120 mg/kg Se (US FDA regulations) from Na selenite. In addition, all cows except controls (CTR) received Se supplementation of 105 mg Se/week from Se-yeast boluses administered once weekly during their specific treatment trimester of gestation (TR1, TR2, or TR3) for 13 weeks. This dosage was supranutritional equaling 5 × the upper range of US FDA Se administration regulations. Blood was collected at parturition from all cows. Laboratory analyses studied to assess humoral immunity included measuring IBR, BVD types 1 and 2, PI3, and BRSV serum neutralization titers post vaccination, assessing total IgM and antigen-specific IgM concentrations, and determining complement-mediated bacterial killing percentages. Statistical analyses were performed using GraphPad Prism and SAS 9.4. Supranutritional Se-yeast supplementation increased whole-blood (WB) Se concentrations regardless of trimester of supplementation (all P < 0.0001). Supplementation during TR2 and TR3 was more effective in increasing WB-Se concentrations at parturition than during TR1 or CTR (all P < 0.0001). TR2 cows had higher serum neutralization titers for BRSV compared with CRT cows (P = 0.03). Total serum IgM and Vibrio coralliilyticus-specific IgM concentrations were highly correlated (r = 0.78; P < 0.0001). Compared with CTR cows, TR1, TR2, and TR3 cows had similar total IgM concentrations (all P ≥ 0.19) and similar Vibrio coralliilyticus-specific IgM concentrations (all P ≥ 0.47). Complement-mediated bacterial killing percentages were greater in TR2 and TR3 cows (> 99.6%) compared with TR1 (93.9%) and CTR (89.3%) cows, and all Se-supplemented TR groups were greater than CTR cows (all P ≤ 0.05). The significant group differences in the complement-mediated bacterial killing assay reflected WB-Se concentrations. Supranutritional Se-yeast supplementation during TR2 and TR3 is associated with higher serum neutralization titers for some viral antigens, as well as enhanced complement-mediated bacterial killing in cows at parturition. These findings suggest that Se supplementation during later trimesters of pregnancy may help combat infectious disease challenges during the periparturient period in beef cattle.

Both Feed Restriction and Transition Period Suppressed Adipose Tissue MRNA Abundance of Genes Involved in Lipogenesis and Lipolysis in Fat-Tailed Ewes

This study sought to investigate the consequences of the induced feed restriction during the transition period on the mRNA abundance of genes entangled in lipogenesis and lipolysis in the tail adipose of fat-tailed sheep. Twenty fat-tailed ewes were randomised into the control (Control; n = 10) and restriction (Restriction; n = 10) groups. Control animals were fed 100% of the balanced diet pre-(Week -5 to parturition) and post-partum (parturition to Week 5). Restriction ewes received equivalent 100%, 50%, 65%, 80%, and 100% of the balanced ration at Weeks -5, -4, -3, -2, and -1 relative to parturition, respectively. After parturition, the latter group received the equivalent of 100%, 50%, 65%, 80%, and 100% of the diet recommendation at weeks 1, 2, 3, 4, and 5, respectively. At the end of weeks -3 and 3, tail adipose were sampled under local anesthesia. Fatty acid synthase, acetyl-CoA carboxylase, carnitine palmitoyltransferase I and II, and acyl-CoA synthase long-chain family member-1 mRNA abundances were measured using the TaqMan quantity real-time PCR. A mixed model procedure of SAS software was used to evaluate the results. Feed restriction downregulated target genes' mRNA abundance during both pre- and post-partum. Parturition suppressed the mRNA abundance of measured genes in both groups. Established on the outcomes, lipogenesis, and lipolysis of the adipose tissue would be influenced by metabolite and hormone instability during the transition period and feed restriction. The lessening of adipose tissue lipogenesis and lipolysis might be a hemostatic response to cope with the energy insufficiency for fetal growth and the onset of lactation and also prevent the induction of inflammation, metabolic disorders, and infectious diseases during feed restriction or transition period.

The teat skin microbiota of organic primiparous dairy cows is dynamic during the transition period

BACKGROUND

The transition period is a critical developmental period for dairy cows, during which the udder undergoes numerous physiological changes that can impact future cow health and performance. The teat skin is an important anatomical feature of the dairy cow, as it is continuously exposed to the environment, and also represents an important barrier against microbes that could invade the teat canal and mammary gland. Yet little is known about the temporal dynamics of the teat skin microbiota during the transition period. Therefore, the main objective of this study was to describe the temporal composition of the teat skin microbiota during the transition period in primiparous dairy cows using 16S rRNA sequencing.

RESULTS

Teat skin swabs were collected throughout the transition period from 710 cows starting their first lactation on 5 certified organic dairy farms. Samples were collected bi-weekly beginning 8 weeks prepartum and then weekly for 4-5 weeks after calving. A total of 4827 teat skin swabs were collected and sequenced, and the resulting sequence data were analyzed by farm and time. Microbial richness, diversity and bacterial load changed dynamically as animals moved through late-stage gestation, parturition and lactation. However, the direction, timing and magnitude of these changes were unique to each farm. Principal component analysis revealed that the composition and structure of the teat skin microbiota also underwent a massive shift during the transition period, with significant differences between phases of the transition period, i.e., late-stage gestation, parturition and lactation. This trend was also observed when samples were categorized into community types using Dirichlet Multinomial Mixture models.

CONCLUSIONS

We observe that the teat skin microbiota comprises a diverse community of bacteria and archaea that experience large shifts in abundance and composition as cows move through the transition period. These shifts begin several weeks prior to calving and continue into the first few weeks postpartum, likely driven by a combination of changing environment, management and host physiology during the same period of time. The specific dynamics of these shifts seem to be fairly unique to each farm, which suggests that farm-level factors are important considerations for future work on the teat skin microbiota of transitioning first-lactation dairy cows.

Effects of postbiotic products from Saccharomyces cerevisiae fermentation on lactation performance, antioxidant capacity, and blood immunity in transition dairy cows

This study aimed to evaluate the effects of dietary supplementation with different types of Saccharomyces cerevisiae fermentation products (SCFP) on lactational performance, metabolism, acute phase protein response, and antioxidant capacity in dairy cows from -21 to 56 DIM. A total of 180 multiparous Holstein dairy cows were blocked by parity, expected calving date, pre-trial BCS, and previous 305-d mature-equivalent milk yield, and then randomly assigned to 1 of 3 dietary treatments: the basal control diet (CON; n = 60), the basal diet supplemented with 40 g/d of XPC (XPC; n = 60; Diamond V, Cedar Rapids, IA), and the basal diet supplemented with 19 g/d of NutriTek (NTK; n = 60, Diamond V). Blood (n = 15, 13, and 12 in the CON, XPC, and NTK groups, respectively) was sampled at -7 (± 3), +3, +7, +21, and +28 d, and milk (n = 19, 18, and 15 in the CON, XPC, and NTK groups, respectively) was sampled from 1 to 8 wk from a subset of cows from -21 to 56 d relative to calving. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). All data were subjected to repeated measures ANOVA. Dietary treatment (Trt), time, and their interaction (Trt × time) were considered as fixed effects and cow as the random effect. Cows fed XPC and NTK had greater ECM yield. Supplementing NTK increased milk fat content and yield and 3.5% FCM yield compared with CON. Milk urea nitrogen was lower in XPC cows than CON. We found that SCFP supplementation decreased plasma BHB, ceruloplasmin, haptoglobin (HPT), and IL-1β concentrations, and it increased plasma P concentrations. In addition, cows fed NTK showed lower creatinine (CR) and cortisol concentrations but increased plasma Ca and myeloperoxidase concentrations than CON cows. In addition, cows fed NTK and XPC both had reduced plasma concentrations of serum amyloid-A (SAA) at 3 DIM compared with CON cows. Furthermore, SCFP cows had greater concentrations of plasma glucose and Ca than CON cows at 7 DIM, and greater concentrations of plasma P at 21 DIM. Between the groups fed different types of SCFP, plasma concentrations of nonesterified fatty acids, malondialdehyde, CR, SAA, and HPT were lower in cows fed NTK compared with cows fed XPC at 7 DIM. Overall, our results indicate the potential benefits of supplementing SCFP in transition dairy cows by modulating immunity and liver metabolic function and supporting ECM yield. The results also suggest that NutriTek at 19 g/d appears to support the performance and health of dairy cows better compared with XPC at 40 g/d, based on improved metabolic and inflammatory status during the transition period.

A potential gateway to understanding liver disease development: peripartum lipid fluctuations in dairy cows

Current lifestyles are leading to a worldwide increase in metabolic liver diseases that favor the development of liver disease. Changes in hepatocytes are caused by altered lipid concentrations, oxidative stress or toxicity by individual lipids. The complexity of the underlying processes and differences of the pathology to proposed rodent models makes the development of an effective targeted therapy difficult. The lipid mobilization that occurs in dairy cows in the postpartum period could be a natural model for the metabolic stress commonly observed in the development of liver diseases. We therefore used gas chromatography and histopathological staining techniques to analyze lipid patterns in diparous and multiparous cows during the peripartum period. The most striking change in lipid composition is the homogenous increase in palmitoleic acid (C16:1n7) content in all cows around the time of calving, with multiparous cows exhibiting consistently higher C16:1n7 levels by the end of the study. Elevated C16:1n7 levels have a potential key role in the development of non-alcoholic steatohepatitis (NASH) and tumorigenesis in the liver. Changes in C16:1n7, therefore, support the idea that lipid mobilization in dairy cows could serve as model for various liver diseases, such as nonalcoholic fatty liver disease (NAFLD) or NASH development.

Dietary supplementation with citrus peel extract in transition period improves rumen microbial composition and ameliorates energy metabolism and lactation performance of dairy cows

BACKGROUND

During the transition period, excessive negative energy balance (NEB) lead to metabolic disorders and reduced milk yield. Rumen microbes are responsible for resolving plant material and producing volatile fatty acids (VFA), which are the primary energy source for cows. In this study, we aimed to investigate the effect of citrus peel extract (CPE) supplementation on rumen microbiota composition, energy metabolism and milk performance of peripartum dairy cows.

METHODS

Dairy cows were fed either a basal diet (CON group) or the same basal diet supplemented with CPE via intragastric administration (4 g/d, CPE group) for 6 weeks (3 weeks before and 3 weeks after calving; n = 15 per group). Samples of serum, milk, rumen fluid, adipose tissue, and liver were collected to assess the effects of CPE on rumen microbiota composition, rumen fermentation parameters, milk performance, and energy metabolic status of dairy cows.

RESULTS

CPE supplementation led to an increase in milk yield, milk protein and lactose contents, and serum glucose levels, while reduced serum concentrations of non-esterified fatty acid, β-hydroxybutyric acid, insulin, aspartate aminotransferase, alanine aminotransferase, and haptoglobin during the first month of lactation. CPE supplementation also increased the content of ruminal VFA. Compared to the CON group, the abundance of Prevotellaceae, Methanobacteriaceae, Bacteroidales_RF16_group, and Selenomonadaceae was found increased, while the abundance of Oscillospiraceae, F082, Ruminococcaceae, Christensenellaceae, Muribaculaceae UCG-011, Saccharimonadaceae, Hungateiclostridiaceae, and Spirochaetaceae in the CPE group was found decreased. In adipose tissue, CPE supplementation decreased lipolysis, and inflammatory response, while increased insulin sensitivity. In the liver, CPE supplementation decreased lipid accumulation, increased insulin sensitivity, and upregulated expression of genes involved in gluconeogenesis.

CONCLUSIONS

Our findings suggest that CPE supplementation during the peripartum period altered rumen microbiota composition and increased ruminal VFA contents, which further improved NEB and lactation performance, alleviated lipolysis and inflammatory response in adipose tissue, reduced lipid accumulation and promoted gluconeogenesis in liver. Thus, CPE might contribute to improve energy metabolism and consequently lactation performance of dairy cows during the transition period.

Altered bile acid and correlations with gut microbiome in transition dairy cows with different glucose and lipid metabolism status

The transition from pregnancy to lactation is critical in dairy cows. Among others, dairy cows experience a metabolic stress due to a large change in glucose and lipid metabolism. Recent studies revealed that bile acids (BA), other than being involved in both the emulsification and solubilization of fats during intestinal absorption, can also affect the metabolism of glucose and lipids, both directly or indirectly by affecting the gut microbiota. Thus, we used untargeted and targeted metabolomics and 16S rRNA gene sequencing approaches to investigate the concentration of plasma metabolites and BA, the composition of the rectum microbial community, and assess their interaction in transition dairy cows. In Experiment 1, we investigated BA and other blood parameters and gut microbiota in dairy cows without clinical diseases during the transition period, which can be seen as well adapted to the challenge of changed glucose and lipid metabolism. As expected, we detected an increased plasma concentrations of BHB and nonesterified fatty acids (NEFA) but decreased concentrations of glucose, cholesterol, and triglycerides (TG). Untargeted metabolomic analysis of the plasma revealed primary BA biosynthesis was one of the affected pathways, and was consistent with the increased concentration of BA in the plasma. A correlation approach revealed a complex association between BA and microbiota with the host plasma concentration of glucose and lipid metabolites. Among BA, chenodeoxycholic acid derivates such as glycolithocholic acid, taurolithocholic acid, lithocholic acid, taurochenodeoxycholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites (such as glucose, TG, and NEFA). In Experiment 2, we investigated early postpartum dairy cows with or without hyperketonemia (HPK). As expected, HPK cows had increased concentration of NEFA and decreased concentrations of glucose and triglycerides. The untargeted metabolomic analysis of the plasma revealed that primary BA biosynthesis was also one of the affected pathways. Even though the BA concentration was similar among the 2 groups, the profiles of taurine-conjugated BA changed significantly. A correlation analysis also revealed an association between BA and microbiota with the concentration in plasma of glucose and lipid metabolites (such as BHB). Among BA, cholic acid and its derivates such as taurocholic acid, tauro α-muricholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites. Our results indicated an association between BA, intestinal microbe, and glucose and lipid metabolism in transition dairy cows. These findings provide new insight into the adaptation mechanisms of dairy cows during the transition period.

Association of uterine health in the first lactation with transition cow health and reproductive performance in the second lactation of Holstein dairy cows

The objective of this study was to evaluate the effects of puerperal metritis (PM) diagnosed and treated during the early postpartum period of the first lactation on transition cow health, milk production, reproduction, and culling of dairy cows in their second lactation. Diagnosis of PM was based on fetid watery red-brown uterine discharge and rectal temperature above 39.5°C. Two farms were enrolled in this retrospective observational cohort study (farms A and B). In both farms, the following diseases were recorded during the first 30 DIM in lactation 1 and 2: clinical hypocalcemia (CH), retained fetal membrane (RFM), PM, hyperketonemia (KET), left displaced abomasum (LDA), and clinical mastitis (MAST). Statistical analyses were performed using SPSS for Windows separately for each farm. Linear and logistic regression models were used for continuous (e.g., milk yield) and binary (e.g., disease, pregnancy per AI, pregnancy loss) outcomes, respectively. Cox proportional hazard regression models were calculated to model the time to event outcomes for culling or death during the first 60 DIM and for pregnancy within 250 d of the second lactation. The initial models contained the following variables: year of calving, month of calving, calving ease, stillbirth, twins, days open in lactation 1, 305-d milk yield in lactation 1, PM in lactation 1, and PM in lactation 2 as explanatory variables. A total of 4,834 cows (farm A) and 4,238 cows (farm B) in the second lactation were considered for statistical analyses. On farm A, the incidence of PM in lactations 1 and 2 were 20.1% and 11.2%, respectively. On farm B, the incidence of PM in lactations 1 and 2 were 14.4% and 8.5%, respectively. On both farms, cows with PM in their first lactation had greater odds for RFM and PM in their second lactation, whereas there was no association of PM in the first lactation with any other nonuterine diseases (i.e., CH, KET, LDA, and MAST) in the second lactation. Cows with PM in lactation 2 had reduced milk yield. The reduction in milk yield in second lactation was greater for cows that already experienced PM in lactation 1. On farm A, cows with PM in their first lactation had a greater hazard for culling within 60 DIM of the second lactation; however, the same association was not present on farm B. Cows with PM in lactation 1 had reduced pregnancy per AI at first service in the second lactation only on farm B. Cows with PM in lactation 2 had reduced pregnancy per AI at first service in the second lactation on both farms. Pregnancy loss in lactation 2 was only associated with PM in lactation 2 but not with PM in lactation 1. On both farms, cows had a reduced hazard for pregnancy in their second lactation within 250 DIM when they experienced PM in either lactation. In conclusion, PM in the first lactation had long-lasting negative consequences (i.e., risk of uterine disease and lower reproductive performance) for cows in their next lactation.

Unraveling metabolic stress response in dairy cows: Genetic control of plasma biomarkers throughout lactation and the transition period

Breeding animals able to effectively respond to stress could be a long-term, sustainable, and affordable strategy to improve resilience and welfare in livestock systems. In the present study, the concentrations of 29 plasma biomarkers were used as candidate endophenotypes for metabolic stress response in single-SNP, gene- and haplotype-based GWAS using 739 healthy lactating Italian Holstein cows and 88,271 variants. Significant genetic associations were found in all the 3 GWAS approaches for plasma γ-glutamyl transferase concentration on BTA17, for paraoxonase on BTA4, and for alkaline phosphatase and zinc on BTA2. On these chromosomes, single-SNP and gene-based chromosome-wide association studies were performed, confirming GWAS findings. The signals identified for paraoxonase, γ-glutamyl transferase, and alkaline phosphatase were in proximity to the genes coding for them. The heritability of these 4 biomarkers ranged from moderate to high (from 0.39 to 0.54). Plasma biomarkers are known to undergo large changes in concentration during metabolic stress in the transition period, with an interindividual variability in the rate of change and recovery time. Genetics may account in part for these differences. To assess this, we studied a subset of 139 periparturient cows homozygous at 3 SNPs known to be respectively associated with concentration of plasma ceruloplasmin, paraoxonase, and γ-glutamyl transferase. We compared the immune-metabolic profile measured in plasma at -7, +5, and +30 d relative to calving between groups of opposite homozygotes. A significant effect of the genotype was found on paraoxonase and γ-glutamyl transferase plasma concentration at all the 3 time points. No evidence for genotype effect was detected for ceruloplasmin. Understanding the genetic control underlying metabolic stress response may suggest new approaches to foster resilience in dairy cows.

Effect of glycerol supplementation in early lactation on metabolic health, milking activity, and production of dairy cows in automated milking system herds

The objective of this study was to quantify the effects of supplementing early-lactation cows with a dry pure glycerol product, delivered through the automated milking system (AMS) concentrate, in the first 21 DIM on metabolic markers, milking behavior, and milk production. In 5 commercial AMS dairy herds, 389 dairy cows were randomly assigned, controlling for parity, 21 d before expected calving to 1 of 2 treatments, within farm: (1) the control group (CON) which received the standard AMS pellet (n = 213) from 1 to 150 DIM; or (2) the glycerol group (GLY), which received the treatment AMS pellet (n = 176) formulated to additionally deliver 250 as fed g/d of glycerol product from 1 to 21 DIM, followed by the standard AMS pellet from 22 to 150 DIM. Across all farms, cows were fed partial mixed rations that were similar in ingredient and nutrient composition. One prepartum blood sample and 5 postpartum blood samples were collected from each cow to determine serum nonesterified fatty acids (NEFA), blood BHB, and blood glucose concentrations. Cow BCS was recorded every 21 d from -21 to 63 DIM. Data were collected and analyzed for the treatment period (1-21 DIM) and a follow-up period (22-150 DIM). We detected no treatment effect on serum NEFA concentrations in the first week of lactation. We detected a treatment by time interaction for blood BHB and blood glucose, where GLY cows tended to have increased BHB concentrations at 5 DIM and had decreased glucose concentrations at 9 and 12 DIM. We detected an interaction of BCS with treatment on the incidence of BHB ≥1.2 mmol/L, whereby over-conditioned CON cows (BCS ≥3.5) were 3.5 times more likely to have a high BHB test than CON cows with normal prepartum BCS. During the treatment period, GLY cows had 0.1 ± 0.05 more successful milkings per day, were delivered 0.27 ± 0.05 DM kg/d more AMS concentrate, and tended to yield 0.8 ± 0.47 kg/d more milk. During the follow-up period, GLY cows had 0.1 ± 0.04 more successful milkings per day, were delivered 0.18 ± 0.06 DM kg/d more AMS concentrate, and yielded 1.5 ± 0.53 kg/d more milk than CON cows. Glycerol supplementation allowed cows to maintain better BCS, as GLY cows lost less BCS from calving to 63 DIM than CON cows. Overall, the results of this study demonstrate that supplementing pure glycerol through the AMS concentrate for the first 21 DIM can reduce BCS loss in early lactation, improve milking behavior, and increase milk yield to mid-lactation.

Metabolites and physical scores as possible predictors for postpartum culling in dairy cows

The purpose of the study was to explore the associations of serum non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) concentrations with the body condition score (BCS) and rumen fill score (RFS) in order to predict the risk of postpartum culling, and to further investigate effective monitoring stages during the dry period. From October 2012 to March 2014, clinically healthy Holstein heifers and cows were sampled once before calving, and the occurrence of culling within 60 days in milk (DIM) was investigated. The discriminatory ability of each parameter was evaluated using receiver operating characteristic (ROC) analysis. Of the 720 cows sampled between 14 and 2 days before the actual day of calving in the study, 42 cull cows (mean DIM ± SE: 22.0 ± 2.6) were confirmed. The areas under the curve (AUC) of the ROC for predicting culling using serum NEFA concentrations were 0.6 and 0.7 at 14 to 2 and 7 to 2 days before calving, respectively. The AUC for the RFS was 0.7 for both periods, indicating the same diagnostic level as the serum NEFA concentration. Both the serum NEFA concentration and RFS were possible predictors in cows with ≥ 2 parities, but not in cows with 0-1 parity sampled even at 7 to 2 days before calving. The serum BHBA concentration and BCS were not suitable predictors of culling for any period or parity. These results indicate that RFS has a discriminatory ability comparable to the serum NEFA concentration for predicting culling within 60 DIM.

Patterns of variation and relationships among fat, protein, and milk yield of individual dairy cattle in a Thai multibreed population

This study systematically examines the patterns of milk yield (MY, kg), fat (FAT, %), and protein (PROT, %) in a diverse population of Thai multibreed dairy cattle, considering the tropical environment's impact on lactating cows. Using a dataset of 47,205 monthly test-day records from 4,440 first-lactation cows across 446 farms, we analyze variations and interrelationships through mathematical averaging and introduce the fat-to-protein ratio (FPR) to assess acidosis (FPR < 1.1) and ketosis (FPR > 1.5) risks during lactation. Pearson correlation analysis elucidated trait associations. The findings, aligned with established lactation norms, indicate peak production at 297 days in milk (DIM) for FAT (4.08%; SD = 0.96%), PROT (3.43%; SD = 0.47%), and 52 DIM for MY (18.09 kg; SD = 4.91 kg). Nadirs are observed at 72 DIM for FAT (3.27%; SD = 0.74%), 47 DIM for PROT (2.86%; SD = 0.36%), and 299 DIM for MY (9.05 kg; SD = 2.95 kg). FPR variations highlight acidosis (46.48%), normal (43.66%), and ketosis (9.86%), especially during early lactation (100 DIM). Significant negative correlations emerge between MY, FAT, and PROT (P < 0.05), while a positive correlation is identified between FAT and PROT (P < 0.01), with robust correlations during early lactation. This study contributes to understanding tailored nutritional strategies for dairy cows' holistic health and sustainability in tropical environments, guiding efficient production practices and mitigating health-related productivity impediments.

Pre- and postpartum metabolizable protein supply: II. Effects on plasma amino acids and markers of tissue mobilization in transition Holstein dairy cows

The influence of diet composition on the degree of adipose and lean muscle mobilization and concentrations of circulating AA has been demonstrated during the transition period. Altering the MP supply might offer a strategy to control tissue mobilization and increase circulating AA availability, but the optimum supply of MP fed pre- and postpartum remains unknown. We investigated the effect of increasing the MP supply in the prepartum, postpartum, or both diets on plasma AA concentrations and ultrasound and circulating indicators of tissue mobilization. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (C; 85 g of MP/kg DM; 1,175 g of MP/d) or high (H; 113 g of MP/kg DM; 1,603 g of MP/d) level of estimated MP. From calving to 21 DIM, fresh diets were formulated to contain either a control (C; 104 g of MP/kg DM; 2,044 g of MP/d) or high (H; 131 g of MP/kg DM; 2,685 g of MP/d) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: 1) CC (n = 23), 2) CH (n = 24), 3) HC (n = 22), and 4) HH (n = 23). A common lactation diet (113 g of MP/kg DM; 2,956 g of MP/d) was fed from 22 DIM to the end of the observation period at 42 DIM. Transcutaneous ultrasonography was used to determine the longissimus dorsi muscle diameter and backfat thickness. Concentrations of plasma AA, 3-methylhistidine (3MH), and creatinine were determined on a subset of cows (n = 60) using ultra-high-performance liquid chromatography and mass spectrometry. Treatment did not affect the longissimus dorsi muscle diameter from -14 to 21 d relative to calving, but the diameter was greater in CH compared with HH at 40 DIM. Backfat thickness and the ratio of 3MH to creatinine did not differ by treatment. Concentrations of EAA were greater at -13 d relative to calving in HH compared with CC and CH and at -6 d relative to calving EAA concentrations were higher in HC compared with CC. Cows fed the H diet postpartum had elevated EAA concentrations at 6 and 20 DIM compared with cows fed the C postpartum diet but EAA concentration did not differ at 40 DIM. Total NEAA concentrations were higher in CH compared with HC and HH at -6 d relative to calving, but NEAA concentration did not differ by treatment at -13, 6, 20, or 40 d relative to calving. In conclusion, increasing the supply of MP fed prepartum, postpartum, or both had minimal effects on tissue mobilization but influenced concentrations of plasma AA.

Pre- and postpartum metabolizable protein supply: I. Effects on feed intake, lactation performance, and metabolic markers in transition dairy cows

The objective of this study was to investigate the effect of increasing MP supply in the prepartum, postpartum, or both diets on intake, performance, and metabolic indicators. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (C; 85 g of MP/kg DM) or high (H; 113 g of MP/kg DM) level of estimated MP. From calving to 21 DIM, diets were formulated to contain either a control (C; 104 g of MP/kg DM) or high (H; 131 g of MP/kg DM) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: 1) CC (n = 23), 2) CH (n = 24), 3) HC (n = 22), and 4) HH (n = 23). A common lactation diet (113 g of MP/kg DM) was fed from 22 DIM to the end of the observation period at 42 DIM. Milk yield and DMI were collected daily, and plasma metabolic indicators (BHB, fatty acids [NEFA], urea nitrogen [PUN], and glucose) were determined twice weekly from -28 to 28 d relative to calving and once weekly from 29 to 42 DIM. Samples with BHB ≥1.2 mmol/L between 3 and 10 DIM were considered hyperketonemia events. Milk composition was determined weekly. Milk yield during 1 to 21 DIM was greater in HH (44.7 ± 1.0 kg/d) compared with CC (39.2 ± 1.0 kg/d) and HC (38.0 ± 1.0 kg/d) and milk yield in CH (42.4 ± 0.9 kg/d) was greater than HC, respectively. From 22 to 42 DIM, milk yield was greater in CH (53.3 ± 1.0 kg/d) and HH (54.1 ± 1.0 kg/d) compared with CC (49.6 ± 1.0 kg/d) and HC (49.3 ± 1.0 kg/d). Dry matter intake (% of BW) and concentrations of milk protein, fat, and total solids were not affected by treatment. Prepartum concentrations of PUN were greater in H compared with C. From 1 to 21 DIM, PUN concentrations were greater in CH and HH compared with CC and HC. From 1 to 21 DIM, glucose concentrations were lower in HH compared with HC and BHB were greater in CH and HH compared with HC. Concentrations of NEFA, as well as the number of hyperketonemia events did not differ by treatment during this time. From 22 to 42 DIM, concentrations of NEFA were greater in HH compared with HC and concentrations of BHB were greater in CH and HH compared with HC. Overall, feeding CH or HH increased lactation performance without altering intake or hyperketonemia events. Results from this study support formulating a fresh diet to reduce the negative MP balance during early lactation.

Liver transcriptome and proteome are modulated by nutrient restriction in early lactation cows challenged with intramammary lipopolysaccharide

The objective was to evaluate the effects of nutrient restriction on liver function 24 h after an intramammary lipopolysaccharide (LPS) challenge in early lactation cows using transcriptomic and proteomic analyses. Multiparous Holstein cows were fed a lactation diet (CONT, n = 8) throughout the study or were switched to a diet diluted with barley straw (48 % DM) for 96 h (REST, n = 8) starting at 24 (18 to 30) days in milk. At 72 h, a healthy rear mammary quarter was infused with 50 μg of LPS in all cows. Blood and liver biopsies were collected at 96 h, corresponding to 24 h after LPS challenge. Liver transcriptome was analyzed with a 44 K bovine microarray and proteome by LC MS/MS. Transcriptomic and proteomic data were analyzed using GeneSpring (moderated t-test with Westfall-Young correction) and the "between subject design", respectively. Data mining was performed using Panther and Pathway Studio software. By design, the negative energy balance was -68 and -37 MJ/d in REST and CONT, respectively. Plasma non-esterified FAs, and β-hydroxybutyrate were significantly greater in REST compared to CONT, which is consistent with 96 h of nutrient restriction in REST and ketosis induction. We detected 77 and 91 differentially expressed genes at mRNA and protein levels, respectively, between CONT and REST. Genes involved in fatty acid synthesis (e.g.: ACAT, FASN, SCD) were downregulated in REST, whereas those involved in fatty acid oxidation, detoxification, cholesterol synthesis, lipoprotein lipid secretion, and gluconeogenesis (e.g.: ACAD, CPT1A, CPT1B, CPT2) were upregulated. Differentially abundant mRNAs and proteins were consistent with negative energy balance and plasma metabolite concentrations, and reflected a state of intense lipomobilization, glucose deficit and ketogenesis in REST cows. Nutrient restriction did not change in deep liver expression of genes directly involved in immune function 24 h after an intramammary LPS challenge.

Rumen microbiota succession throughout the perinatal period and its association with postpartum production traits in dairy cows: A review

The transition period for dairy cows usually refers to the 3 weeks pre-calving to the 3 weeks post-calving. During this period, dairy cows undergo metabolic and physiological adaptations because of their susceptibility to metabolic and infectious diseases. Poor feeding management under these circumstances may adversely affect the health and subsequent production performance of the cows. Owing to long-term adaptation and evolution, the rumen has become a unique ecosystem inhabited by a complex microbial community closely associated with its natural host. Dietary components are metabolized by the rumen microbiota, and volatile fatty acids and microbial protein products can be used as precursor substances for synthesizing meat and milk components. The successful transition of perinatal dairy cows includes changes in diet, physiology, and the rumen microbiota. Rumen microbial profiles have been confirmed to be heritable and repairable; however, adverse circumstances affect rumen microbial composition, host digestion and metabolism, as well as postpartum production traits of dairy cows for a certain period. Preliminary evidence indicates a close relationship between the rumen microbiota and animal performance. Therefore, changes in rumen microbes during the transition period and the intrinsic links between the microbiota and host postpartum phenotypic traits need to be better understood to optimize production performance in ruminants.

Feeding rumen-protected methionine during the peripartum period improved milk fat content and reduced the culling rate of Holstein cows in a commercial herd

Researchers have reported the benefits of feeding rumen-protected methionine (RPM) during the peripartum on the health parameters of dairy cows. Rumen-protected Met has reportedly improved milk yield, milk components, and liver health, but the literature is scarce on its effects in commercial herds. Therefore, we aimed to determine the effects of feeding RPM (Smartamine M, Adisseo Inc., Antony, France) prepartum (8 g/cow per day) and postpartum (15 g/cow per day) on performance, metabolic profile, and culling rate of Holstein cows in a commercial herd. One hundred sixty-six (n = 166) Holstein cows, 58 nulliparous and 108 parous, were randomly assigned to 1 of 2 dietary treatments, consisting of TMR top-dressed with RPM (RPMet; 2.35% and 2.24% Met of MP for close-up and fresh cows, respectively) or without (control [CON] 2.03% and 1.89% Met of MP for close-up and fresh cows, respectively), fed from 21 ± 6 d prepartum until 16 ± 5 d postpartum. From 17 DIM until dry-off, all cows received RPMet. Daily milk yield was recorded, and milk samples were collected in the first and second weeks after calving to determine their composition. Blood samples were collected before the morning feeding on -14, -7, +1, +7, and +14 d relative to calving. Mortality and morbidity were recorded during the first 60 DIM. Cows supplemented with RPMet had greater milk yield during the first 16 DIM (31.76 vs. 30.37 kg/d; SEM = 1.04, respectively), and had greater milk fat content (4.45 vs. 4.10%; SEM = 0.11, respectively), but not milk total protein (3.47 vs. 3.39%; SEM = 0.04, respectively) and casein contents (2.74 vs. 2.66%; SEM = 0.04, respectively) than CON cows. Cows in RPMet had increased plasma Met concentrations than cows in CON (24.9 vs. 21.0 µmol/L; SEM = 1.2, respectively). Although morbidity was similar between treatments, the culling rate from calving until 60 DIM was lower for RPMet cows than for CON cows (2.4% vs. 12.1%; SEM = 0.02). In conclusion, cows receiving RPMet have greater milk yield, improved milk fat content, and a lower culling rate at 60 DIM than CON cows.

Prepartum anti-inflammatory therapies in Holstein dairy cows blocked by parity and body condition score group: Effects on metabolic stress, systemic inflammation, performance, and health

The objective of this study was to assess the effects of prepartum administration of anti-inflammatory therapies on body condition score (BCS), β-hydroxybutyrate (BHB) concentration, haptoglobin (HP) concentration, milk yield, milk components, rumination time, clinical health events and reproductive performance in Holstein dairy cows. At 14 d before the expected calving date, cows (PAR; n = 170) and heifers (nulliparous [NUL]; n = 63) were blocked by BCS group (optimal = 3-3.5 [OPT]; over-conditioned cows [OVERC; BCS ≥ 3.75 pts.]) and parity (NUL; PAR) and randomly allocated to one of 3 treatment groups: 1) ASA (n = 78): receive one oral administration of acetylsalicylic acid (4 boluses; 480 grain/bolus); 2) MEL (n = 76): receive one oral administration with meloxicam (1mg/kg of BW), or 3) PLC (n = 77): receive one oral treatment with gelatin capsules filled with water. Body condition score was assessed, and blood samples were collected, weekly starting one week before treatment until 3 weeks after calving. Daily milk yields and daily rumination times were collected from on-farm computer records. Dairy Herd Improvement Association (DHIA) monthly test data were collected to assess milk yield, somatic cell counts, and milk components. Furthermore, health events, culling rate, and reproductive performance data were collected from on-farm computer records. The data were analyzed using MIXED, GLIMMIX, and LIFETEST procedures of SAS as a randomized complete block design. On average, MEL-NUL cows produced 4.77 ± 0.93 kg/d and 4.81 ± 0.92 kg/d more milk from wk 6 to wk 21 of lactation compared with ASA-NUL and PLC-NUL cows, respectively. Similarly, there was a week by treatment by body condition group interaction (P = 0.01), where OVERC cows treated with MEL produced more milk from wk 10 to wk 15 of lactation compared with ASA- OVERC and PLC-OVERC cows. Parous cows treated with ASA had lower BCS compared with PAR cows treated with MEL or PLC. A lower percentage of OVERC cows treated with ASA became sick in the first 60 DIM compared with MEL- OVERC and PLC- OVERC cows (ASA = 23.88 ± 7.26%, MEL = 46.36 ± 8.57%; PLC = 46.74 ± 8.53%; P = 0.04). Parous cows treated with ASA had (P = 0.03) a higher hazard ratio to become pregnant by 300 DIM compared with PAR MEL cows. Although the study was not sized for finding treatment differences in blocking criteria groups, these results suggest that treatment with prepartum anti-inflammatory therapies may have positive effects on milk yield and postpartum health in specific groups of cows, such as NUL and OVERC cows, while it may not be recommended for other animal categories, such as parous cows and cows with optimal BCS. Larger studies are needed to strengthen the associations observed in this study.

DNA Methylation of Postnatal Liver Development in Pigs

DNA methylation plays an important role in the development and tissue differentiation of eukaryotes. In this study, bisulfite sequencing (BS-seq) technology was used to analyze the DNA methylation profiles of liver tissues taken from Rongchang pigs at three postnatal feeding stages, including newborn, suckling, and adult. The DNA methylation pattern across the genomes or genic region showed little difference between the three stages. We observed 419 differentially methylated regions (DMRs) in promoters, corresponding to 323 genes between newborn and suckling stages, in addition to 288 DMRs, corresponding to 134 genes, between suckling and adult stages and 351 DMRs, corresponding to 293 genes, between newborn and adult stages. These genes with DMRs were mainly enriched in metabolic, immune-related functional processes. Correlation analysis showed that the methylation level of gene promoters was significantly negatively correlated with gene expression. Further, we found that genes related to nutritional metabolism, e.g., carbohydrate metabolism (FAHD1 and GUSB) or fatty acid metabolism (LPIN1 and ACOX2), lost DNA methylation in their promoter, with mRNA expression increased in newborn pigs compared with those in the suckling stage. A few fatty acid metabolism-related genes (SLC27A5, ACOX2) were hypomethylated and highly expressed in the newborn stage, which might satisfy the nutritional requirements of Rongchang pigs with high neonatal birth rates. In the adult stage, HMGCS2-which is related to fatty acid β-oxidation-was hypomethylated and highly expressed, which explains that the characteristics of high energy utilization in adult Rongchang pigs and their immune-related genes (CD68, STAT2) may be related to the establishment of liver immunity. This study provides a comprehensive analysis of genome-wide DNA methylation patterns in pig liver postnatal development and growth. Our findings will serve as a valuable resource in hepatic metabolic studies and the agricultural food industry.

Effects of Early Lactation Milking Frequency in an Automated Milking System on Cow Performance

Automated milking systems (AMS) are increasingly adopted for dairy cow production, promoting individualized cow management dependent on factors like lactation stage, age, and productivity. The study objective was to investigate the effects of early lactation milking frequency on cows milked via AMS. Multiparous Holstein cows blocked by parity and due date were randomly assigned to treatments (n = 8 per treatment): three (3X) or six (6X) milkings per day (MPD). The experimental phase (EXP) was defined as 4 to 29 days in milk (DIM). The AMS settings were programed so 3X cows were limited to three MPD while 6X cows were allowed six MPD. Afterwards was the carry over phase (CO) ranging from 30 to 90 DIM; all cows were allowed up to six MPD. Measurements by the AMS included bodyweight, milk yield (MY), and pellet intake. Weekly composite milk samples were analyzed for macronutrient composition and fatty acid (FA) profile. Coccygeal blood was sampled at 3, 8 ± 1, and 13 ± 1 DIM; concentrations of blood plasma analytes were quantified. Greater MPD was achieved for 6X cows versus 3X cows during EXP, but similar during the CO. Daily MY was non-separable during the EXP while 6X cows in their third or greater lactation group (3 + LG) had greater MY than 3X cows of the same LG during the CO. Milk fat content and 4% fat-corrected MY were both greater for 6X, 3 + LG cows during the EXP compared to 3X, 3 + LG cows. Milk FA methyl esters (FAME) proportions were different between MPD groups, with 6X, 3 + LG cows having the lowest short, even-chain FA from de novo or post-absorptive origin. Differences in analytes indicated that 6X, 3 + LG cows experienced metabolic stress and incorporated greater FA from adipose tissue. Greater early lactation MPD in AMS may shift cow nutrient partitioning to support greater production in 3+ parity cows.

Intravenous lipopolysaccharide challenge in early- versus mid-lactation dairy cattle. II: The production and metabolic responses

Most immunometabolic research uses mid-lactation (ML) cows. Cows in early lactation (EL) are in a presumed state of immune suppression/dysregulation and less is known about how they respond to a pathogen. Study objectives were to compare the production and metabolic responses to i.v. LPS and to differentiate between the direct effects of immune activation and the indirect effects of illness-induced hypophagia in EL and ML cows. Cows in EL (n = 11; 20 ± 2 DIM) and ML (n = 12; 131 ± 31 DIM) were enrolled in a 2 × 2 factorial design containing 2 experimental periods (P). During P1 (3 d), cows were fed ad libitum and baseline data were collected. At the initiation of P2 (3 d), cows were randomly assigned to 1 of 2 treatments by lactation stage (LS): (1) EL (EL-LPS; n = 6) or ML (ML-LPS; n = 6) cows administered i.v. a single bolus of 0.09 µg LPS/kg of BW; Escherichia coli O55:B5 or (2) pair-fed (PF) EL (EL-PF; n = 5) or ML (ML-PF; n = 6) cows administered i.v. saline. Administering LPS decreased DMI and this was more severe in EL-LPS than ML-LPS cows (34% and 11% relative to baseline, respectively). By design, P2 DMI patterns were similar in the PF groups compared with their LPS counterparts. Milk yield decreased following LPS (42% on d 1 relative to P1) and despite an exacerbated decrease in EL-LPS cows on d 1 (25% relative to ML-LPS), remained similar between LS from d 2 to 3. The EL-LPS cows had increased milk fat content, but no difference in protein and lactose percentages compared with ML-LPS cows. Further, cumulative ECM yield was increased (21%) in EL-LPS compared with ML-LPS cows. During P2, EL-LPS cows had a more intense increase in MUN and BUN than ML-LPS and EL-PF cows. Administering LPS did not cause hypoglycemia in either EL-LPS or ML-LPS cows, but glucose was increased (33%) in EL-LPS compared with EL-PF. Hyperinsulinemia occurred after LPS, and insulin was further increased in ML-LPS than EL-LPS cows (2.2-fold at 12 h peak). During P2, circulating glucagon increased only in EL-LPS cows (64% relative to all other groups). Both EL groups had increased NEFA at 3 and 6 h after LPS from baseline (56%), but NEFA in EL-LPS cows gradually returned to baseline thereafter and were reduced relative to EL-PF until 36 h (50% from 12 to 24 h). Alterations in BHB did not differ between ML groups, but EL-LPS had reduced BHB compared with EL-PF from 24 to 72 h (51%). Results indicate that there are distinct LS differences in the anorexic and metabolic responses to immune activation. Collectively, EL cows are more sensitive to the catabolic effects of LPS than ML cows, but these exacerbated metabolic responses appear coordinated to fuel an augmented immune system while simultaneously supporting milk synthesis.

Intravenous lipopolysaccharide challenge in early- versus mid-lactation dairy cattle. I: The immune and inflammatory responses

Cows in early lactation (EL) are purportedly immune suppressed, which renders them more susceptible to disease. Thus, the study objective was to compare key biomarkers of immune activation from i.v. LPS between EL and mid-lactation (ML) cows. Multiparous EL (20 ± 2 DIM; n = 11) and ML (131 ± 31 DIM; n = 12) cows were enrolled in a 2 × 2 factorial design and assigned to 1 of 2 treatments by lactation stage (LS): (1) EL (EL-LPS; n = 6) or ML (ML-LPS; n = 6) cows administered a single LPS bolus from Escherichia coli O55:B5 (0.09 µg/kg of BW), or (2) pair-fed (PF) EL (EL-PF; n = 5) or ML (ML-PF; n = 6) cows administered i.v. saline. After LPS administration, cows were intensely evaluated for 3 d to analyze their response and recovery to LPS. Rectal temperature increased in LPS relative to PF cows (1.1°C in the first 9 h), and the response was more severe in EL-LPS relative to ML-LPS cows (2.3 vs. 1.3°C increase at 4 h post-LPS; respectively). Respiration rate increased only in EL-LPS cows (47% relative to ML-LPS in the first hour post-LPS). Circulating tumor necrosis factor-α, IL-6, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1α, MIP-1β, and IFN-γ-inducible protein-10 increased within the first 6 h after LPS and these changes were exacerbated in EL-LPS relative to ML-LPS cows (6.3-fold, 4.8-fold, 57%, 93%, 10%, and 61%, respectively). All cows administered LPS had decreased circulating iCa relative to PF cows (34% at the 6 h nadir), but the hypocalcemia was more severe in EL-LPS than ML-LPS cows (14% at 6 h nadir). In response to LPS, neutrophils decreased regardless of LS, then increased into neutrophilia by 24 h in all LPS relative to PF cows (2-fold); however, the neutrophilic phase was augmented in EL- compared with ML-LPS cows (63% from 24 to 72 h). Lymphocytes and monocytes rapidly decreased then gradually returned to baseline in LPS cows regardless of LS; however, monocytes were increased (57%) at 72 h in EL-LPS relative to ML-LPS cows. Platelets were reduced (46%) in LPS relative to PF cows throughout the 3-d following LPS, and from 24 to 48 h, platelets were further decreased (41%) in EL-LPS compared with ML-LPS. During the 3-d following LPS, serum amyloid A (SAA), LPS-binding protein (LBP), and haptoglobin (Hp) increased in LPS compared with PF groups (9-fold, 72%, and 153-fold, respectively), and the LBP and Hp responses were more exaggerated in EL-LPS than ML-LPS cows (85 and 79%, respectively) whereas the SAA response did not differ by LS. Thus, our data indicates that EL immune function does not appear "suppressed," and in fact many aspects of the immune response are seemingly functionally robust.

Role of hypoxia-inducible-factor-1α (HIF-1α) in ferroptosis of adipose tissue during ketosis

Postpartum cows experience lipolysis in adipose tissue due to negative energy balance (NEB), and accumulation of free fatty acids (FFA) leads to metabolic stress in adipose tissue. Ferroptosis is a type of cell death triggered by excessive buildup of iron-dependent lipid peroxides, which is involved in the occurrence and development of various metabolic diseases in nonruminants. However, it is still unclear whether ferroptosis occurs in the adipose tissue of ketotic cows and the regulatory mechanisms behind ferroptosis. Despite multiple studies demonstrating the significant involvement of hypoxia-inducible-factor-1α (HIF-1α) in regulating cellular dysfunction, its specific function in adipose tissue of ketotic dairy cows remains uncertain, particularly its regulation of oxidative stress and ferroptosis. The study aimed to explore the impact of HIF-1α on oxidative stress and ferroptosis in bovine subcutaneous adipose tissue and isolated adipocytes. The adipose tissue of clinical ketosis cows (n = 15) with a serum BHB concentration of 3.13 mM (interquartile range = 0.14) and healthy cows (n = 15) with a serum BHB concentration of and 0.58 mM (interquartile range = 0.13) was collected. The results showed that the concentrations of lipid peroxidation malondialdehyde (MDA), reactive oxygen species (ROS), Fe2+ and total iron were increased in adipose tissue of cows with ketosis, while the contents of glutathione (GSH) were reduced. Furthermore, the protein levels of HIF-1α, heme oxygenase 1 (HMOX1), catalase (CAT), superoxide dismutase 1 (SOD1), acyl-CoA synthetase 4 (ACSL4), and nuclear factor erythroid-derived 2-like 2 (NFE2L2) exhibited higher abundance in adipose tissue obtained from cows with ketosis, whereas the protein abundance of solute carrier family 7 member 11 (SLC7A11), glutamate cysteine ligase catalytic subunit (GCLC), kelch-like ECH-associated protein 1 (KEAP1), glutamate cysteine ligase regulatory subunit (GCLM) and glutathione peroxidase 4 (GPX4) were lower. To simulate the ferroptosis state of adipose tissue in ketotic cows, primary bovine adipocytes were isolated from the adipose tissue of healthy cows and cultured with erastin to construct ferroptosis model. Adipocytes were cultured with either an adenovirus overexpressing HIF-1α or small interfering RNA targeting HIF-for 48 h, followed by exposure to erastin (1 μM) for 24 h. Treatment with erastin led to higher protein abundance of CAT, SOD1, NFE2L2 and HMOX1, while it inhibited the protein expression levels of GCLC, SLC7A11, GCLM, GPX4 and KEAP1. Furthermore, erastin treatment elevated the levels of ROS, MDA, Fe2+, total iron and reduced the content of GSH. The overexpression of HIF-1α reversed the erastin-induced decreases in the protein abundance of GPX4 and SLC7A11, as well as the levels of MDA, ROS, Fe2+ and total iron, while significantly increasing protein abundance and content of CAT, SOD1, NFE2L2, HMOX1, GCLC, GCLM, GPX4, SLC7A11 and GSH. Conversely, the silencing of HIF-1α further exacerbated the erastin-induced levels of MDA, ROS, Fe2+ and total iron, while inhibiting the upregulation of SOD1, CAT, NFE2L2 and HMOX1. Collectively, these findings suggest that activation of HIF-1α may function as an adaptive mechanism to mitigate ferroptosis and alleviate oxidative stress in adipose tissue.

Effects of dietary zinc on the gut microbiome and resistome of the gestating cow and neonatal calf

Zinc is an essential trace element required in the diet of all species. While the effects of zinc have been studied in growing calves, little is known about the effect of zinc on the microbiota of the gestating cow or her neonatal calf. Understanding factors that shape the gut health of neonatal animals and evaluating the effect of dietary supplements in adult gestating animals is important in promoting animal health and informing feeding practices. The aims of this study were to determine the effect of dietary zinc on the microbiota and resistome of the gestating cow and calf. Gestating cows received standard (40 ppm) or high (205 ppm) dietary zinc levels from dry off to calving. Fecal samples were collected from cows upon enrollment and at calving and from neonatal calves. Fecal samples underwent 16S rRNA sequencing and a subset also underwent shotgun metagenomic sequencing. The effect of zinc supplementation on the diversity and composition of the cow and calf microbiome and resistome was assessed. Alpha and beta diversity and composition of the microbiota were significantly altered over time but not by treatment in the cows, with alpha diversity decreasing and 14 genera found at significantly higher relative abundances at calving compared to enrollment. Levels of 27 antimicrobial resistance genes significantly increased over time. Only a small number of taxa were differentially expressed at calving in treatment and control groups, including Faecalibacterium, Bacteroides, Turicibacter, and Bifidobacterium pseudolongum. No effect of the dam's treatment group was observed on the diversity or composition of the neonatal calf microbiota. The calf resistome, which was relatively rich and diverse compared to the cow, was also unaffected by the dam's treatment group. The impact of high levels of dietary zinc thus appeared to be minimal, with no observed changes in alpha or beta diversity, and few changes in the relative abundance of a small number of taxa and antimicrobial resistance genes.

Association between non-esterified fatty acids and calcium concentrations at calving with early lactation clinical diseases, fertility and culling in grazing dairy cows in Uruguay

This study describes the association of non-esterified fatty acids (NEFA) and calcium concentrations at calving with early lactation disease, reproductive performance and culling in 646 dairy cows from 13 commercial grazing dairy herds in Uruguay. During one year, health events were recorded from calving to 30 days in milk (DIM). The first author visited each farm every 20 days. During each visit, body condition score (BCS) was recorded (scale 1-5), defining BCS < 3 as suboptimal and BCS > 3 as optimal, and a blood sample was taken from cows between 0 and 4 DIM for metabolite determination. To evaluate the association between health events (i.e., retained placenta-metritis and clinical mastitis) and risk factors (parity, BCS, high NEFA (> 0.6 mmol/L) and subclinical hypocalcemia (SCH) (< 2.10 mM)) data were analysed using multivariable logistic regression models. To evaluate the association of health events and risk factors with reproductive performance and culling, data were analysed using Cox proportional hazard regression models. A risk factor and an outcome of interest were assumed to be associated at P < 0.05 and a tendency to be associated was defined at P < 0.10. Overall, 47 % (n = 303) of the cows showed elevated NEFA concentration and 77 % (n = 499) had SCH. In addition, 21.5 % (n = 139) of the cows recorded at least one clinical disease. Cumulative incidence was 17 % (n = 109) for clinical mastitis, 4.2 % (n = 27) for retained placenta (RP)-metritis and 1.4 % (n = 7) for lameness. Clinical mastitis was associated with parity, with lower odds in primiparous (PP) cows (OR = 0.42, P < 0.01). Cows in an optimal BCS also tended to have lower odds (OR = 0.66, P = 0.07). Moreover, high NEFA and SCH cows had higher odds of CM (OR = 4.5, P = 0.01 and OR = 1.75, P = 0.04, respectively). Retained placenta-metritis tended to be associated with high NEFA concentration (OR = 2.2, P = 0.06). Primiparous cows with suboptimal BCS showed an increased first insemination rate (HR = 2.34; P < 0.01). The risk of culling was lower in PP cows (HR = 0.19; P < 0.01) and in cows with optimal BCS and low NEFA concentration (HR = 0.38; P = 0.03). Our data show that metabolic challenge (defined as peripartum suboptimal BCS, high NEFA or SCH) is associated with increased odds of clinical mastitis and RP-metritis, decreased probability of insemination and increased hazard of culling. Under grazing conditions, we suggest that farm management to improve the metabolic adaptation to lactation represents an opportunity to enhance cow performance in terms of health, fertility and longevity.