Nutrition, rumen health and inflammation in the transition period and their role on overall health and fertility in dairy cows

Effects of Prepartum L-Tryptophan Supplementation on the Postpartum Performance of Holstein Cows

The negative energy balance occurring in the periparturient period of cows will impede their health and postpartum performance. To target this issue, L-tryptophan was supplied to the prepartum cows. The results showed that L-tryptophan supplementation significantly increased the serum melatonin level and was accompanied with increases in SOD activity, IL-10 and colostrum IgA levels as well as decreases in MDA and IL-6 levels compared to the control cows. The incidence of postpartum diseases was significantly lower and the pregnancy rate was significantly higher in cows fed L-tryptophan than in the control group. A striking observation was that prepartum L-tryptophan supplementation not only improved the milk production but also the quality compared to the control cows. In general, supplementation with L-tryptophan in the prepartum period can improve the postpartum reproduction and lactation performance of cows to some extent.

Invited review: "Probiotic" approaches to improving dairy production: Reassessing "magic foo-foo dust"

The gastrointestinal microbial consortium in dairy cattle is critical to determining the energetic status of the dairy cow from birth through her final lactation. The ruminant's microbial community can degrade a wide variety of feedstuffs, which can affect growth, as well as production rate and efficiency on the farm, but can also affect food safety, animal health, and environmental impacts of dairy production. Gut microbial diversity and density are powerful tools that can be harnessed to benefit both producers and consumers. The incentives in the United States to develop Alternatives to Antibiotics for use in food-animal production have been largely driven by the Veterinary Feed Directive and have led to an increased use of probiotic approaches to alter the gastrointestinal microbial community composition, resulting in improved heifer growth, milk production and efficiency, and animal health. However, the efficacy of direct-fed microbials or probiotics in dairy cattle has been highly variable due to specific microbial ecological factors within the host gut and its native microflora. Interactions (both synergistic and antagonistic) between the microbial ecosystem and the host animal physiology (including epithelial cells, immune system, hormones, enzyme activities, and epigenetics) are critical to understanding why some probiotics work but others do not. Increasing availability of next-generation sequencing approaches provides novel insights into how probiotic approaches change the microbial community composition in the gut that can potentially affect animal health (e.g., diarrhea or scours, gut integrity, foodborne pathogens), as well as animal performance (e.g., growth, reproduction, productivity) and fermentation parameters (e.g., pH, short-chain fatty acids, methane production, and microbial profiles) of cattle. However, it remains clear that all direct-fed microbials are not created equal and their efficacy remains highly variable and dependent on stage of production and farm environment. Collectively, data have demonstrated that probiotic effects are not limited to the simple mechanisms that have been traditionally hypothesized, but instead are part of a complex cascade of microbial ecological and host animal physiological effects that ultimately impact dairy production and profitability.

Rumen-protected methionine supplementation alters lipid profile of preimplantation embryo and endometrial tissue of Holstein cows

Our objective is to evaluate the effects of feeding rumen-protected Met (RPM) throughout the transition period and early lactation on the lipid profile of the preimplantation embryos and the endometrial tissue of Holstein cows. Treatments consisted of feeding a total mixed ration with top-dressed RPM (Smartamine® M, Adisseo, Alpharetta, GA, United States; MET; n = 11; RPM at a rate of 0.08% of DM: Lys:Met = 2.8:1) or not (CON; n = 9, Lys:Met = 3.5:1). Endometrial biopsies were performed at 15, 30, and 73 days in milk (DIM). Prior to the endometrial biopsy at 73 DIM, preimplantation embryos were harvested via flushing. Endometrial lipid profiles were analyzed using multiple reaction monitoring-profiling and lipid profiles of embryos were acquired using matrix assisted laser desorption/ionization mass spectrometry. Relative intensities levels were used for principal component analysis. Embryos from cows in MET had greater concentration of polyunsaturated lipids than embryos from cows in CON. The endometrial tissue samples from cows in MET had lesser concentrations of unsaturated and monounsaturated lipids at 15 DIM, and greater concentration of saturated, unsaturated (specifically diacylglycerol), and monounsaturated (primarily ceramides) lipids at 30 DIM than the endometrial tissue samples from cows in CON. In conclusion, feeding RPM during the transition period and early lactation altered specific lipid classes and lipid unsaturation level of preimplantation embryos and endometrial tissue.

Elucidating the factors and consequences of the severity of rumen acidosis in first-lactation Holstein cows during transition and early lactation

First-lactation cows are particularly prone to subacute ruminal acidosis (SARA) during transition. Besides common risk factors of SARA, such as feeding of starch-rich diets, an individual severity of SARA in cows has been recently evidenced. Yet, the factors that play a role in SARA severity have not been elucidated. The main goal of this research was to evaluate the factors of SARA severity in first-lactation cows during transition and early lactation, which go beyond high-grain feeding, and to explore their impact on behavior, health, and fermentation in the rumen and hindgut. Twenty-four first-lactation Holstein cows with the same feeding regime were used starting from 3 wk before the expected calving day until 10 wk postpartum. Cows received a close-up diet (32% concentrate) until calving and were then transitioned to a lactation diet (60% concentrate) within 1 week. The SARA severity was assessed by cluster analysis of several rumen pH metrics, which revealed exceptionally longer and more severe SARA in cows denominated as high (n = 9), as compared to moderate (n = 9) and low (n = 6) SARA severity cows (P < 0.01). The logistic analysis showed that the length of close-up feeding, age at parturition, and the level of dry matter intake (DMI) were the main factors that influenced the cows' odds for high SARA severity (each P ≤ 0.01). Moreover, the ANOVA hinted differences in the metabolic activity of the ruminal microbiome to promote SARA severity, as indicated by highest ruminal propionate proportions (P = 0.05) in high SARA severity cows, also with similar DMI. The distinct SARA severity was marginally reflected in behavior and there were no effects of SARA severity or high-grain feeding on blood inflammation markers, which peaked at parturition regardless of SARA severity (P < 0.01). Still, ongoing high-grain feeding increased liver enzyme concentrations from 6 wk postpartum on, compared to weeks before (P < 0.01), yet irrespectively of SARA severity. In conclusion, first-lactation cows differed in SARA severity under the same feeding regime, which was ascribed to management factors and differences in ruminal fermentation. Further research is warranted to validate these findings and to understand the mechanisms behind differences in the metabolic function of rumen microbiome, in particular in terms of evaluating markers for various SARA severity, as well as to evaluate potential long-term effects on health, performance, fertility, and longevity of dairy cows.

Peripartum factors associated with variation in voluntary postpartum hay intake in dairy cows

The objective of this research was to assess variation in postpartum hay intake when offered alongside total mixed ration (TMR) as free choice, and identify factors related to the hay intake. Twenty multiparous cows were fed a closeup TMR (21.5% starch, 39.1% neutral detergent fiber [NDF] on a dry matter [DM] basis). After calving, cows were offered free choice timothy hay (61.6% NDF, 9.6% crude protein) in addition to a fresh cow TMR (26.8% starch, 33.0% NDF) for the first 5 d postpartum. Cows were fed individually with separate mangers for TMR and hay, each offered ad libitum. Prepartum DM intake (DMI) was recorded, and baseline blood samples were collected after calving, but before the first postpartum feeding. Free choice hay intake ranged from 0 to 4.7 kg/d (DM basis) or 0 to 55.2% (% of total DMI). Cows that consumed more hay (% of total DMI) from d 1 through 5 postpartum had lower DMI 2 d before calving (r = -0.63), and greater baseline concentrations of plasma β-hydroxybutyrate (r = 0.60) and serum haptoglobin (r = 0.68). Additionally, hay intake (% of total DMI) from d 1 through 5 postpartum tended to be positively related to baseline plasma fatty acid concentration (r = 0.41). These findings suggest that cows with lower intake before calving and cows with greater ketone production and inflammation at calving may consume more hay, when offered separate from TMR.

Sodium Propionate Relieves LPS-Induced Inflammation by Suppressing the NF-ĸB and MAPK Signaling Pathways in Rumen Epithelial Cells of Holstein Cows

Subacute ruminal acidosis (SARA) is a prevalent disease in intensive dairy farming, and the rumen environment of diseased cows acidifies, leading to the rupture of gram-negative bacteria to release lipopolysaccharide (LPS). LPS can cause rumentitis and other complications, such as liver abscess, mastitis and laminitis. Propionate, commonly used in the dairy industry as a feed additive, has anti-inflammatory effects, but its mechanism is unclear. This study aims to investigate whether sodium propionate (SP) reduces LPS-induced inflammation in rumen epithelial cells (RECs) and the underlying mechanism. RECs were stimulated with different time (0, 1, 3, 6, 9, 18 h) and different concentrations of LPS (0, 1, 5, 10 μg/mL) to establish an inflammation model. Then, RECs were treated with SP (15, 25, 35 mM) or 10 μM PDTC in advance and stimulated by LPS for the assessment. The results showed that LPS (6h and 10 μg/mL) could stimulate the phosphorylation of NF-κB p65, IκB, JNK, ERK and p38 MAPK through TLR4, and increase the release of TNF-α, IL-1β and IL-6. SP (35 mM) can reduce the expression of cytokines by effectively inhibiting the NF-κB and MAPK inflammatory pathways. This study confirmed that SP inhibited LPS-induced inflammatory responses through NF-κB and MAPK in RECs, providing potential therapeutic targets and drugs for the prevention and treatment of SARA.

Use of intravaginal lactic acid bacteria prepartum as an approach for preventing uterine disease and its association with fertility of lactating dairy cows

The objective of this study was to evaluate the effects of the use of intravaginal probiotics prepartum on the incidence risk of metritis postpartum and conception risk after first artificial insemination (AI). A total of 606 Holstein cows were enrolled 3 wk before their expected calving date from 2 farms. Cows were randomly assigned to either receive a 2-mL dose of a combination of 3 lactic acid bacteria (probiotic treatment) washed with approximately 2 mL of a sterile saline solution, into the vaginal canal twice weekly until parturition, or no intervention (control). Metritis diagnoses were carried out on 6 and 12 d postpartum. Vaginal discharge and rectal temperature were assessed, and vaginal discharge was scored on a scale from 1 to 4, where 1 = clear and 4 = fetid, purulent discharge. Metritis was defined as cows having a vaginal discharge score of 4 with or without fever (rectal temperature ≥39.5°C) on either 6 or 12 d postpartum, or both. Cows were bred after a 60-d voluntary waiting period primarily via the detection of estrus using automated activity monitors; cows not found in estrus were enrolled onto timed AI protocols to receive first breeding before 100 DIM. Pregnancy diagnosis was carried out at d 35 ± 7 post-AI on both farms. Data were analyzed via ANOVA using linear mixed regression models and survival analysis using a Cox proportional hazard model. Total incidence risk of metritis was 23.7% and 34.4% on farm A and farm B, respectively. Overall, the incidence of metritis was not different between treatment groups (control: 41.6 ± 3.8%; probiotic: 38.6 ± 4.0%); however, an interaction by farm was detected, where the probiotic treatment reduced metritis on one farm but not on the other. Conception risk after first AI was not affected by treatment. However, we detected an interaction between parity and treatment, where multiparous cows receiving the probiotic treatment were more likely to become pregnant compared with multiparous cows within the control group (hazard ratio: 1.33; 95% confidence interval: 1.10-1.60); no effect of probiotic treatment was found on the hazard of pregnancy for primiparous cows. In addition, the probiotic treatment was associated with an increased proportion of cows being detected in estrus for the first AI postpartum. In conclusion, vaginal probiotic treatment applied during the 3 wk prepartum was associated with a decreased incidence of metritis on one farm but not the other, suggesting that farm management may be a key player influencing treatment efficacy. Overall, probiotic treatment was found to have only limited effects on fertility in the current study.

Effects of High Concentrate-Induced Subacute Ruminal Acidosis Severity on Claw Health in First-Lactation Holstein Cows

This study aimed to evaluate the effects of diet-induced subacute rumen acidosis (SARA) severity during transition and the early lactation period on claw health in 24 first-lactation Holstein heifers. All heifers were fed a 30% concentrate (in dry matter) close-up ration three weeks before calving, then switched to a high-concentrate ration (60% dry matter), which was fed until the 70th day in milk (DIM) to induce SARA. Thereafter, all cows were fed the same post-SARA ration with around 36% concentrate in dry matter. Hoof trimming was performed before calving (visit 1), at 70 (visit 2) and at 160 DIM (visit 3). All claw lesions were recorded, and a Cow Claw Score (CCS) was calculated for each cow. Locomotion scores (LCS 1-5) were assessed at two-week intervals. Intraruminal sensors for continuous pH measurements were used to determine SARA (pH below 5.8 for more than 330 min in 24 h). The cluster analysis grouped the cows retrospectively into light (≤11%; n = 9), moderate (>11-<30%; n = 7), and severe (>30%; n = 8) SARA groups, based on the percentage of days individual cows experienced SARA. Statistically significant differences were found between SARA groups light and severe in terms of lameness incidence (p = 0.023), but not for LCS and claw lesion prevalence. Further, the analysis of maximum likelihood estimates revealed that for each day experiencing SARA, the likelihood of becoming lame increased by 2.52% (p = 0.0257). A significant increase in white line lesion prevalence was observed between visits 2 and 3 in the severe SARA group. The mean CCS in severe SARA group cows were higher at each visit compared to cows in the other two groups, but without statistical significance. Overall, this is the first study indicating that first-lactation cows fed a similar high-concentrate diet but with a higher severity of SARA tended to have poorer claw health, albeit with only partial statistical evidence.

Effect of supplementing live Saccharomyces cerevisiae yeast on performance, rumen function, and metabolism during the transition period in Holstein dairy cows

Dairy cows have to face several nutritional challenges during the transition period, and live yeast supplementation appears to be beneficial in modulating rumen activity. In this study, we evaluated the effects of live yeast supplementation on rumen function, milk production, and metabolic and inflammatory conditions. Ten Holstein multiparous cows received either live Saccharomyces cerevisiae (strain Sc47; SCY) supplementation from -21 to 21 d from calving (DFC) or a control diet without yeast supplementation. Feed intake, milk yield, and rumination time were monitored until 35 DFC, and rumen fluid, feces, milk, and blood samples were collected at different time points. Compared with the control diet, SCY had increased dry matter intake (16.7 vs. 19.1 ± 0.8 kg/d in wk 2 and 3) and rumination time postpartum (449 vs. 504 ± 19.9 min/d in wk 5). Milk yield tended to be greater in SCY (40.1 vs. 45.2 ± 1.7 kg/d in wk 5), protein content tended to be higher, and somatic cell count was lower. In rumen fluid, acetate molar proportion was higher and that of propionate lower at 21 DFC, resulting in increased acetate:propionate and (acetate + butyrate):propionate ratios. Cows in the SCY group had lower fecal dry matter but higher acetate and lower propionate proportions on total volatile fatty acids at 3 DFC. Plasma analysis revealed a lower degree of inflammation after calving in SCY (i.e., lower haptoglobin concentration at 1 and 3 DFC) and a likely better liver function, as suggested by the lower γ-glutamyl transferase, even though paraoxonase was lower at 28 DFC. Plasma IL-1β concentration tended to be higher in SCY, as well as Mg and P. Overall, SCY supplementation improved rumen and hindgut fermentation profiles, also resulting in higher dry matter intake and rumination time postpartum. Moreover, the postcalving inflammatory response was milder and liver function appeared to be better. Altogether, these effects also led to greater milk yield and reduced the risk of metabolic diseases.

Invited review: Rumen modifiers in today's dairy rations

Our aim was to review feed additives that have a potential ruminal mechanism of action when fed to dairy cattle. We discuss how additives can influence ruminal fermentation stoichiometry through electron transfer mechanisms, particularly the production and usage of dihydrogen. Lactate accumulation should be avoided, especially when acidogenic conditions suppress ruminal neutral detergent fiber digestibility or lead to subclinical acidosis. Yeast products and other probiotics are purported to influence lactate uptake, but growing evidence also supports that yeast products influence expression of gut epithelial genes promoting barrier function and resulting inflammatory responses by the host to various stresses. We also have summarized methane-suppressing additives for potential usage in dairy rations. We focused on those with potential to decrease methane production without decreasing fiber digestibility or milk production. We identified some mitigating factors that need to be addressed more fully in future research. Growth factors such as branched-chain volatile fatty acids also are part of crucial cross-feeding among groups of microbes, particularly to optimize fiber digestibility in the rumen. Our developments of mechanisms of action for various rumen-active modifiers should help nutrition advisors anticipate when a benefit in field conditions is more likely.

Predicted functional analysis of rumen microbiota suggested the underlying mechanisms of the postpartum subacute ruminal acidosis in Holstein cows

BACKGROUND

The relationships between the postpartum subacute ruminal acidosis (SARA) occurrence and predicted bacterial functions during the periparturient period are still not clear in Holstein cows.

OBJECTIVES

The present study was performed to investigate the alterations of rumen fermentation, bacterial community structure, and predicted bacterial functional pathways in Holstein cows.

METHODS

Holstein cows were divided into the SARA (n = 6) or non-SARA (n = 4) groups, depending on whether they developed SARA during the first 2 weeks after parturition. Reticulo-ruminal pH was measured continuously during the study period. Reticulo-ruminal fluid samples were collected 3 weeks prepartum, and 2 and 6 weeks postpartum, and blood samples were collected 3 weeks before, 0, 2, 4 and 6 weeks postpartum.

RESULTS

The postpartum decline in 7-day mean reticulo-ruminal pH was more severe and longer-lasting in the SARA group compared with the non-SARA group. Changes in predicted functional pathways were identified in the SARA group. A significant upregulation of pathway "PWY-6383" associated with Mycobacteriaceae species was identified at 3 weeks after parturition in the SARA group. Significantly identified pathways involved in denitrification (DENITRIFICATION-PWY and PWY-7084), detoxification of reactive oxygen and nitrogen species (PWY1G-0), and starch degradation (PWY-622) in the SARA group were downregulated.

CONCLUSIONS

The postpartum SARA occurrence is likely related to the predicted functions of rumen bacterial community rather than the alterations of rumen fermentation or fluid bacterial community structure. Therefore, our result suggests the underlying mechanisms, namely functional adaptation of bacterial community, causing postpartum SARA in Holstein cows during the periparturient period.

The mechanistic target of rapamycin complex 1 pathway involved in hepatic gluconeogenesis through peroxisome-proliferator-activated receptor γ coactivator-1α

Cattle can efficiently perform de novo generation of glucose through hepatic gluconeogenesis to meet post-weaning glucose demand. Substantial evidence points to cattle and non-ruminant animals being characterized by phylogenetic features in terms of their differing capacity for hepatic gluconeogenesis, a process that is highly efficient in cattle yet the underlying mechanism remains unclear. Here we used a variety of transcriptome data, as well as tissue and cell-based methods to uncover the mechanisms of high-efficiency hepatic gluconeogenesis in cattle. We showed that cattle can efficiently convert propionate into pyruvate, at least partly, via high expression of acyl-CoA synthetase short-chain family member 1 (ACSS1), propionyl-CoA carboxylase alpha chain (PCCA), methylmalonyl-CoA epimerase (MCEE), methylmalonyl-CoA mutase (MMUT), and succinate-CoA ligase (SUCLG2) genes in the liver (P < 0.01). Moreover, higher expression of the rate-limiting enzymes of gluconeogenesis, such as phosphoenolpyruvate carboxykinase (PCK) and fructose 1,6-bisphosphatase (FBP), ensures the efficient operation of hepatic gluconeogenesis in cattle (P < 0.01). Mechanistically, we found that cattle liver exhibits highly active mechanistic target of rapamycin complex 1 (mTORC1), and the expressions of PCCA, MMUT, SUCLG2, PCK, and FBP genes are regulated by the activation of mTORC1 (P < 0.001). Finally, our results showed that mTORC1 promotes hepatic gluconeogenesis in a peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) dependent manner. Collectively, our results not only revealed an important mechanism responsible for the quantitative differences in the efficiency of hepatic gluconeogenesis in cattle versus non-ruminant animals, but also established that mTORC1 is indeed involved in the regulation of hepatic gluconeogenesis through PGC-1α. These results provide a novel potential insight into promoting hepatic gluconeogenesis through activated mTORC1 in both ruminants and mammals.

Addition of clinoptilolite in the diet reduces uterine PMN leukocytes and open days in multiparous lactating dairy cows managed in a mountain tropical pasture-based system

This study aimed to assess the effect of adding clinoptilolite in the diet on uterine health and reproductive performance in multiparous lactating dairy cows managed in a tropical pasture-based system above 2500 m of altitude. Seventy-seven multiparous Holstein crossbred cows from two farms were allocated randomly into two groups: clinoptilolite supplemented cows (CLG, n = 42) and non-supplemented cows as control (CG, n = 35). Cows from CLG were supplemented with clinoptilolite from 30 days (50 g/cow/day) before to 60 days after calving (200 g/cow/day). In CLG cows, percentages of uterine PMN leukocytes (P < 0.0001) and proportion of subclinical endometritis (P = 0.0187) were lower than in CG. The interval calving to first corpus luteum was shorter (P = 0.0759) in CLG than CG, and calving to first service interval was similar between treatments. Cows from CLG became pregnant 35 days earlier than CG cows (P = 0.0224). On farm A, calving to conception interval was 18.1 days longer in CLG than in CG (P = 0.3750); in farm B, this interval was 86.2 days shorter in CLG than in CG (P = 0.0002). In conclusion, daily addition of clinoptilolite in the diet decreased the percentage of uterine PMN leukocytes, the proportion of cows with subclinical endometritis, and shortened the calving-conception interval in multiparous lactating dairy cows.

Yak rumen microbiome elevates fiber degradation ability and alters rumen fermentation pattern to increase feed efficiency

Rumen microbes play an important role in ruminant energy supply and animal performance. Previous studies showed that yak (Bos grunniens) rumen microbiome and fermentation differ from other ruminants. However, little is understood about the features of the rumen microbiome that make yak adapted to their unique environmental and dietary conditions. This study was to investigate the rumen microbiome and metabolome to understand how yak adapt to the coarse forage and harsh environment in the Qinghai-Tibetan plateau. Nine female Qaidam yellow cattle (Bos taurus), 9 dzomo (hybrids of cattle and yak) and 9 female plateau yak (B. grunniens), about 5 to 6 years old, were used in this study. Rumen fermentation parameters, fibrolytic enzyme activities, and rumen metataxonomic were determined. Then 18 (6 samples per group) were selected for rumen metagenomic and metabolome analysis. Metataxonomic analysis revealed that the rumen microbiota was significantly different among plateau yak, Qaidam yellow cattle, and dzomo (P < 0.05). Metagenomic analysis displayed a larger gene pool encoding a richer repertoire of carbohydrate-active enzymes in the rumen microbiome of plateau yak and dzomo than Qaidam yellow cattle (P < 0.05). Some of the genes encoding glycoside hydrolases that mediate the digestion of cellulose and hemicellulose were significantly enriched in the rumen of plateau yak than Qaidam yellow cattle, but glycoside hydrolase 57 that primarily includes amylases was abundant in Qaidam yellow cattle (P < 0.05). The rumen fermentation profile differed also, Qaidam yellow cattle having a higher molar proportion of acetate but a lower molar proportion of propionate than dzomo and plateau yak (P < 0.05). Based on metabolomic analysis, rumen microbial metabolic pathways and metabolites were different. Differential metabolites are mainly amino acids, carboxylic acids, sugars, and bile acids. Changes in rumen microbial composition could explain the above results. The present study showed that the rumen microbiome of plateau yak helps its host to adapt to the Qinghai-Tibetan plateau. In particular, the plateau yak rumen microbiome has more enzymes genes involved in cellulase and hemicellulase than that of cattle, resulting higher fibrolytic enzyme activities in yak, further providing stronger fiber degradation function.

Pharmacological inhibition of the mTOR pathway alters phenotype and cytokine expression in bovine monocyte-derived dendritic cells

Epidemiological studies have long demonstrated the association of nutrient status and immune dysfunction in dairy cows. Postpartum dairy cows experiencing a nutrient deficit show a propensity for increased inflammatory response, decreased pathogen clearance, and increased incidence of infectious disease. Studies in cows and other species show that the nutrient sensing mechanistic target of rapamycin (mTOR) signaling pathway could be one potential causal pathway connecting the deficit in nutrient availability and the heightened inflammatory response. Our objective was to investigate the effects of pharmacological mTOR pathway inhibition on phenotype and cytokine expression of bovine monocyte derived dendritic cells (moDC). We differentiated CD14⁺ monocytes from dairy cows (n = 14) into moDC in the presence or absence of first- or second-generation mTOR inhibitor rapamycin and PP242 (both 100 nM), respectively. On day seven cells were matured with E. coli lipopolysaccharide (LPS, 100 ng/mL) or left unstimulated to represent naïve moDC. Surface expression of CD14, CD40, CD80, and MHCII was measured via flow cytometry. We measured mRNA expression of IL10, IL12A, IL12B, and TNFα by rt-qPCR, and protein concentrations of IL-10 and TFN-α in cell culture supernatants with a bead-based multiplex assay. Cultures from ten cows successfully developed the moDC phenotype in culture without inhibitors, defined as increased surface expression of CD40, CD80, and MHCII compared with naïve moDC. Only data from these cows were considered for the results on effects of mTOR inhibitors. In naïve and mature moDC mTOR inhibition increased MHCII expression compared to controls. In mature moDC, in addition to MHCII, CD80 expression was increased compared with untreated LPS-stimulated controls. Expression of IL12A mRNA was upregulated in mature, mTOR inhibited moDC compared with untreated controls. In cell culture supernatants mTOR inhibition reduced IL-10 and increased TNF-α concentrations in naïve and mature moDCs compared with untreated controls. Overall rapamycin had a more consistent effect on altering phenotype and cytokine expression of moDC than PP242. In summary we observed an increased expression of co-stimulatory molecules and antigen presentation potential in mature moDC differentiated under mTOR inhibition, and a cytokine pattern that would potentially favor a Th1 type response. This study provides novel data indicating a role for mTOR signaling in bovine moDC phenotype and mediator profile. This proof-of-concept study demonstrates the role of the mTOR pathway in shaping the bovine immune response and may help to provide mechanistic insight and opportunities for modulation of the immune response during the nutrient deficit of early lactation.

Calcium Propionate Supplementation Has Minor Effects on Major Ruminal Bacterial Community Composition of Early Lactation Dairy Cows

Calcium propionate is one kind of good source for preventing and treating hypocalcemia and ketosis for dairy cows in early lactation. However, little is known about the effects of different feeding levels of calcium propionate on the ruminal bacterial community of early lactation dairy cows. This study aimed to explore the effects of different calcium propionate feeding levels on the ruminal fermentation and bacterial community composition of early lactation dairy cows. Twenty-four multiparous cows were randomly allocated into control (CON), low calcium propionate (LCaP), medium calcium propionate (MCaP), and high calcium propionate (HCaP) groups with six cows per group after calving. The CON group cows were fed the normal total mixed ration (TMR), and the cows of the LCaP, MCaP, and HCaP groups were fed TMR supplemented with 200, 350, and 500 g/day calcium propionate for 35 days after calving, respectively. The rumen fermentation parameters were measured every week, and the ruminal bacterial community composition of the last week was analyzed by 16S rRNA gene sequencing. Under the same diet, the rumen pH showed no difference among the four groups, but the content of microbial crude protein (MCP) and ammonia nitrogen quadratically decreased and linearly increased with calcium propionate supplementation, respectively. The feeding of calcium propionate linearly increased the concentrations of total volatile fatty acid (VFA), acetate, propionate, butyrate, iso-valerate, and valerate in the rumen. In all the treatment groups, Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla, and Prevotella_1 and Succiniclasticum were the dominant genera in the rumen. Compared with the CON group, the addition of calcium propionate to the early lactation dairy cows quadratically improved the alpha diversity index of Chao1 estimator and observed species, but had little effect on the relative abundance of the major bacterial at phyla and genera level. These results suggested different levels of calcium propionate supplementation improved the rumen fermentation and the ruminal bacterial diversity but had little impact on the major ruminal bacterial community composition of dairy cows in early lactation.

The microbiome of the buffalo digestive tract

Buffalo is an important livestock species. Here, we present a comprehensive metagenomic survey of the microbial communities along the buffalo digestive tract. We analysed 695 samples covering eight different sites in three compartments (four-chambered stomach, intestine, and rectum). We mapped ~85% of the raw sequence reads to 4,960 strain-level metagenome-assembled genomes (MAGs) and 3,255 species-level MAGs, 90% of which appear to correspond to new species. In addition, we annotated over 5.8 million nonredundant proteins from the MAGs. In comparison with the rumen microbiome of cattle, the buffalo microbiota seems to present greater potential for fibre degradation and less potential for methane production. Our catalogue of microbial genomes and the encoded proteins provides insights into microbial functions and interactions at distinct sites along the buffalo digestive tract.

Major Nutritional Metabolic Alterations Influencing the Reproductive System of Postpartum Dairy Cows

Early successful conception of postpartum dairy cows is crucial in determining the optimum reproductive efficiency and profitability in modern dairy farming. Due to the inherent high production potential of modern dairy cows, the extra stress burden of peri-parturient events, and associated endocrine and metabolic changes causes negative energy balance (NEBAL) in postpartum cows. The occurrence of NEBAL is associated with excessive fat mobilization in the form of non-esterified fatty acids (NEFAs). The phenomenon of NEFA mobilization furthers with occurrence of ketosis and fatty liver in postpartum dairy cows. High NEFAs and ketones are negatively associated with health and reproductive processes. An additional burden of hypocalcemia, ruminal acidosis, and high protein metabolism in postpartum cows presents further consequences for health and reproductive performance of postpartum dairy cows. This review intends to comprehend these major nutritional metabolic alterations, their mechanisms of influence on the reproduction process, and relevant mitigation strategies.

The Transition Period Updated: A Review of the New Insights into the Adaptation of Dairy Cows to the New Lactation

Recent research on the transition period (TP) of dairy cows has highlighted the pivotal role of immune function in affecting the severity of metabolic challenges the animals face when approaching calving. This suggests that the immune system may play a role in the etiology of metabolic diseases occurring in early lactation. Several studies have indicated that the roots of immune dysfunctions could sink way before the “classical” TP (e.g., 3 weeks before and 3 weeks after calving), extending the time frame deemed as “risky” for the development of early lactation disorders at the period around the dry-off. Several distressing events occurring during the TP (i.e., dietary changes, heat stress) can boost the severity of pre-existing immune dysfunctions and metabolic changes that physiologically affect this phase of the lactation cycle, further increasing the likelihood of developing diseases. Based on this background, several operational and nutritional strategies could be adopted to minimize the detrimental effects of immune dysfunctions on the adaptation of dairy cows to the new lactation. A suitable environment (i.e., optimal welfare) and a balanced diet (which guarantees optimal nutrient partitioning to improve immune functions in cow and calf) are key aspects to consider when aiming to minimize TP challenges at the herd level. Furthermore, several prognostic behavioral and physiological indicators could help in identifying subjects that are more likely to undergo a “bad transition”, allowing prompt intervention through specific modulatory treatments. Recent genomic advances in understanding the linkage between metabolic disorders and the genotype of dairy cows suggest that genetic breeding programs aimed at improving dairy cows’ adaptation to the new lactation challenges (i.e., through increasing immune system efficiency or resilience against metabolic disorders) could be expected in the future. Despite these encouraging steps forward in understanding the physiological mechanisms driving metabolic responses of dairy cows during their transition to calving, it is evident that these processes still require further investigation, and that the TP—likely extended from dry-off—continues to be “the final frontier” for research in dairy sciences.

Invited review: Mechanisms of hypophagia during disease

Suppression of appetite, or hypophagia, is among the most recognizable effects of disease in livestock, with the potential to impair growth, reproduction, and lactation. The continued evolution of the field of immunology has led to a greater understanding of the immune and endocrine signaling networks underlying this conserved response to disease. Inflammatory mediators, especially including the cytokines tumor necrosis factor-α and interleukin-1β, are likely pivotal to disease-induced hypophagia, based on findings in both rodents and cattle. However, the specific mechanisms linking a cytokine surge to decreased feeding behavior are more difficult to pin down and likely include direct effects on appetite centers in the brain, alteration of gastric motility, and modulation of other endocrine factors that influence appetite and satiety. These insights into the mechanisms for disease-induced hypophagia have great relevance for management of neonatal calves, mature cows transitioning to lactation, and cows experiencing mastitis; however, it is not necessarily the case that increasing feed intake by any means possible will improve health outcomes for diseased cattle. We explore conflicting effects of hypophagia on immune responses, which may be impaired by the lack of specific substrates, versus apparent benefits for controlling the growth of some pathogens. Anti-inflammatory strategies have shown promise for promoting recovery of feed intake following some conditions but not others. Finally, we explore the potential for early disease detection through automated monitoring of feeding behavior and consider which strategies may be implemented to respond to early hypophagia.

MicroRNA: Could It Play a Role in Bovine Endometritis?

Endometritis in dairy cows is a major economic problem worldwide; without advances in lifestyle management and drug treatment, it causes high morbidity and death. Micro ribonucleic acid (miRNAs) these days is seen as an important part of gene control networks. It is a class of small nucleotides 20-25, single-stranded RNA molecules. In endometritis, the inflammatory response caused by the gram-negative bacteria Escherichia coli (E. coli) alters the expression of miRNA which can regulate the innate immune system. This manuscript reviews (1) the interaction of miRNAs with the signaling of NF-κB and dysregulation of miRNAs and NF-κB activity in endometritis and (2) the activity of miR-let-7c, miR-148a, and miR-488 in NF-κB activation and their effect on endometritis. Cows with reduced immunity are more vulnerable to transition diseases, such as endometritis. During post-partum, cows undergo stress, metabolic disorders, hormonal imbalance, negative energy balance, and changes in diet. One of the many categories of regulatory molecules, which explain its natural function and pathological impact on NF-κB dysregulation, is important to inform the complexity of the immune system and to develop treatments for endometritis. It shows that miRNAs could have multiple applications in veterinary medicine. Nevertheless, a comprehensive study of is essential which should be aimed at exploring the role of microRNA at physiological level and its effect due to dysfunction and dysregulation.

Dairy cow health and management in the transition period: The need to understand the human dimension

During the transition from the dry period to lactation the dairy cow undergoes a period of physiological, metabolic and immunological change, and is at greater risk of developing disease, to the detriment of health, welfare and production. Many studies have been undertaken to determine appropriate management strategies to improve health and welfare during the transition period, however the incidence of disease, particularly metabolic disease, in this period remains high. To date, a lack of research attention has been paid to the social factors which may affect the management of transition dairy cows. An understanding of farmer and advisor attitudes and behaviour, and the challenges they face in managing transition cows, may help to direct farmers towards more effective disease prevention and control. It is also possible that transition cow morbidity may be due to complex interactions that are difficult to manage, despite efforts to implement best practice. This review paper provides a brief overview of some of the management factors that may influence herd health during the transition period. It then investigates how social influences may relate to the uptake of transition management practices by exploring the use of qualitative interviews investigating farmer and stakeholder attitudes and behaviour in relation to cattle health and welfare, before focussing more specifically on farmer behaviour. Additionally, this paper explores farm advisor behaviour, and how that has been shown to influence farmer adherence to advice, which has particular relevance to transition cow management. It then suggests potential research strategies to investigate the human influences affecting the scale of the problem that may provide solutions to tackle the challenge of improving dairy cow health and welfare.

Association of fibre degradation with ruminal dissolved hydrogen in growing beef bulls fed with two types of forages

The present study investigated the association between fibre degradation and the concentration of dissolved molecular hydrogen (H2) in the rumen. Napier grass (NG) silage and corn stover (CS) silage were compared as forages with contrasting structures and degradation patterns. In the first experiment, CS silage had greater 48-h DM, neutral-detergent fibre (NDF) and acid-detergent fibre degradation, and total gas and methane (CH4) volumes, and lower 48-h H2 volume than NG silage in 48-h in vitro incubations. In the second experiment, twenty-four growing beef bulls were fed diets including 55 % (DM basis) NG or CS silages. Bulls fed the CS diet had greater DM intake (DMI), average daily gain, total-tract digestibility of OM and NDF, ruminal dissolved methane (dCH4) concentration and gene copies of protozoa, methanogens, Ruminococcus albus and R. flavefaciens, and had lower ruminal dH2 concentration, and molar proportions of valerate and isovalerate, in comparison with those fed the NG diet. There was a negative correlation between dH2 concentration and NDF digestibility in bulls fed the CS diet, and a lack of relationship between dH2 concentration and NDF digestibility with the NG diet. In summary, the fibre of CS silage was more easily degraded by rumen microorganisms than that of NG silage. Increased dCH4 concentration with the CS diet presumably led to the decreased ruminal dH2 concentration, which may be helpful for fibre degradation and growth of fibrolytic micro-organisms in the rumen.

The Use of Artificial Neural Networks and a General Discriminant Analysis for Predicting Culling Reasons in Holstein-Friesian Cows Based on First-Lactation Performance Records

The aim of the present study was to verify whether artificial neural networks (ANN) may be an effective tool for predicting the culling reasons in cows based on routinely collected first-lactation records. Data on Holstein-Friesian cows culled in Poland between 2017 and 2018 were used in the present study. A general discriminant analysis (GDA) was applied as a reference method for ANN. Considering all predictive performance measures, ANN were the most effective in predicting the culling of cows due to old age (99.76-99.88% of correctly classified cases). In addition, a very high correct classification rate (99.24-99.98%) was obtained for culling the animals due to reproductive problems. It is significant because infertility is one of the conditions that are the most difficult to eliminate in dairy herds. The correct classification rate for individual culling reasons obtained with GDA (0.00-97.63%) was, in general, lower than that for multilayer perceptrons (MLP). The obtained results indicated that, in order to effectively predict the previously mentioned culling reasons, the following first-lactation parameters should be used: calving age, calving difficulty, and the characteristics of the lactation curve based on Wood's model parameters.

Effects of pre- and postpartum dietary starch content on productivity, plasma energy metabolites, and serum inflammation indicators of dairy cows

The objective of this study was to evaluate the effects of the starch content of pre- and postpartum diets on productivity, plasma energy metabolites, and serum markers of inflammation of dairy cows during the calving transition period. Eighty-eight primiparous and multiparous cows were randomly assigned to pre- and postpartum dietary treatments balanced for parity and pretrial body condition score at d 28 ± 3 before expected calving date. Cows were fed either a control [Control; 14.0% starch, dry matter (DM) basis] or high-starch (High; 26.1% starch, DM basis) prepartum diet commencing 28 ± 3 d before expected calving date. Following calving, cows were fed either a high-fiber (HF; 33.8% neutral detergent fiber, 25.1% starch, DM basis) or high-starch (HS; 27.2% neutral detergent fiber, 32.8% starch, DM basis) postpartum diet for the first 20 ± 2 d following calving. Cows fed the High prepartum diet had greater DM intake (12.4 vs. 10.2 kg/d), plasma concentrations of insulin (1.72 vs. 14.2 ng/mL), glucose (68.1 vs. 65.0 mg/dL), and glucagon-like peptide-2 (0.41 vs. 0.32 ng/mL) before parturition, but increased plasma free fatty acid concentration (452 vs. 363 µEq/L) and milk fat yield (1.64 vs. 1.48 kg/d) after parturition. Cows fed the HS postpartum diet had lower plasma free fatty acid (372 vs. 442 µEq/L) and serum haptoglobin (0.46 vs. 0.70 mg/mL) concentrations over a 3-wk period after calving. In addition, there was a tendency for interaction between prepartum and postpartum diets for milk yield, where feeding the HS postpartum diet increased milk yield compared with the HF diet for cows fed the Control prepartum diet (40.8 vs. 37.9 kg/d) but not for cows fed the High prepartum diet. These results suggest that management efforts to minimize the change in diet fermentability during the calving transition by feeding the High prepartum diet, the HF postpartum diet, or both did not increase productivity of dairy cows but increased fat mobilization after calving. Our findings also suggest that feeding high-starch postpartum diets can decrease fat mobilization and serum indicators of systemic inflammation and increase milk production even with the transition from a low-starch prepartum diet.

Supplementation with beta-1,3-glucan improves productivity, immunity and antioxidative status in transition Holstein cows

Dairy cows undergo dramatic physiological changes during the transition from late pregnancy to early lactation, which make them vulnerable to metabolic stress and immune dysfunction. The objective of this study was to evaluate the effects of a commercial beta-1,3-glucan product (Aleta™, containing 50% beta-1,3-glucan) on productivity, immunity and antioxidative status in transition cows. Fifty-four multiparous Holstein cows received a control diet or a diet supplemented with 5 or 10 g of beta-1,3-glucan per cow per day from 21 days before expected calving to 21 days after parturition. Blood samples were collected at day -21, 1, and 21 relative to calving. Colostrum and milk were collected at day 1 and 21 after calving, respectively. Data showed that supplementation with beta-1,3-glucan had no effect on milk composition, but increased milk production. Beta-1,3-glucan treatment also improved the milk quality, as shown by reduced milk somatic cell count and increased immunoglobulin levels in colostrum. Notably, beta-1,3-glucan markedly reduced serum levels of pro-inflammatory cytokines and C-reactive protein, while elevated serum immunoglobulin levels, indicating its immunity enhancement in transition cows. Moreover, beta-1,3-glucan addition reduced the serum malondialdehyde level and enhanced the activities of serum superoxide dismutase and catalase, which enhanced the antioxidative capacity in transition cows. In summary, supplementation with beta-1,3-glucan improves productivity, immunity and antioxidative status in transition dairy cows.

Starch-Rich Diet Induced Rumen Acidosis and Hindgut Dysbiosis in Dairy Cows of Different Lactations

Simple Summary

High-producing dairy cows receive high-energy diets for maintenance and production. This study showed that 60% concentrate in the diet, containing 27.7% starch, changed the fecal-microbial community and lowered its diversity, suggesting hindgut dysbiosis. Both ruminal and fecal pH decreased with high-starch feeding, which suggests further investigations in fecal pH as rumen- and hindgut-acidosis diagnostic tool. Cows in the third lactation spent more time below the threshold for subacute-ruminal acidosis (pH 6.0) than second or fourth-or-below lactation cows. Their higher susceptibility was caused by their high dry matter intake but missing counter-regulation by increased rumination activity. Further, we suggest that body weight and rumen size might play a role in the absorptive capacity of short-chain fatty acids. The study also identified indicator-bacterial phylotypes that changed with starch-rich diet and lactation number. In conclusion, we suggest including lactation number as a factor in practical feeding management for identification of high risk-cows for acidosis, and in dairy cow research.

Abstract

Starch-rich diets can cause subacute ruminal acidosis (SARA) in dairy cows with potentially different susceptibility according to lactation number. We wanted to evaluate the bacterial community and the fermentation end products in feces to study susceptibility to hindgut acidosis and dysbiosis. Sixteen dairy cows received a medium-concentrate diet (MC, 40% concentrate, 18.8% starch) for one week and a high-concentrate diet (HC, 60% concentrate, 27.7% starch, DM) for four weeks. Milk yield, dry-matter intake, chewing activity, ruminal pH, milk constituents, and fecal samples for short-chain fatty acids (SCFA), pH, and 16S rRNA-gene sequencing were investigated. The HC feeding caused a reduction in fecal pH, bacterial diversity and richness, an increase in total SCFA, and a separate phylogenetic clustering of MC and HC samples. Ruminal and fecal pH had fair correlation (r = 0.5). Cows in the second lactation (2ndL) had lower dry matter intake (DMI) than cows of third or fourth or more lactations (3rdL; ≥4 L), whereas DMI/kg body weight was lower for ≥4 L than for 2ndL and 3rdL cows. The mean ruminal pH was highest in ≥4 L, whereas the time spent below the SARA threshold was highest for 3rdL cows. The latter also had higher total SCFA in the feces. Our results suggest that hindgut dysbiosis is caused by increased substrate flow to the hindgut, but further investigations are needed to define hindgut acidosis. The 3rdL cows were most susceptible to rumen acidosis and hindgut dysbiosis due to high DMI level, but missing counter regulations, as suggested happening in 2ndL and ≥4 L cows.

Effects of beta-1,3-glucan supplementation on concentrations of serum metabolites in transition Holstein cows

Objectives of this study were to evaluate the alleviating effects of a commercial beta-1,3-glucan product (Aleta, containing 50% beta-1,3-glucan, Kemin Industries) on metabolic stress in transition Holstein cows as reflected by circulating metabolites and enzymes. Fifty-four multiparous Holstein cows were randomly allocated to three groups with 18 cows each. Cows in each group received a commercial basal diet or the basal diet supplemented with Aleta calculated to supply 5 or 10 g of Aleta per cow per day. Blood samples were collected at day -21, 1, and 21 relative to calving for determination of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDLC), very low density lipoprotein (VLDL), glucose, insulin, β-hydroxybutyric acid (BHBA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamyl transpeptidase (GGT), and non-esterified fatty acid (NEFA). Supplementation with Aleta markedly elevated serum concentrations of TG, TC, HDLC, LDL-C and VLDL, implying its positive effect on lipid metabolism in transition dairy cows. Aleta treatment significantly decreased the serum concentrations of NEFA and BHBA, but markedly elevated the serum concentrations of glucose and insulin. Also, Aleta treatment significantly elevated the dry matter intake and milk production in postpartum cows, indicating the alleviating effect of Aleta on negative energy balance in transition cows. Moreover, Aleta treatment significantly reduced the serum activities of AST, ALT and GGT, indicating its hepatoprotective effect on transition cows. These results suggest that Aleta supplementation may help to improve fat metabolism disorder initiated by negative energy balance in transition dairy cows.

Effects of micronutrient supplementation on performance and epigenetic status in dairy cows

The postpartum period is crucial in dairy cows and is marked by major physiological and metabolic changes that affect milk production, immune response and fertility. Nutrition remains the most important lever for limiting the negative energy balance and its consequences on general health status in highly selected dairy cows. In order to analyze the effect of a commercial micronutrient on intrinsic parameters, performances and the epigenome of dairy cows, 2 groups of 12 Holstein cows were used: 1 fed a standard diet (mainly composed of corn silage, soybean meal and non-mineral supplement) and the other 1 fed the same diet supplemented with the commercial micronutrient (µ-nutrient supplementation) for 4 weeks before calving and 8 weeks thereafter. Milk production and composition, BW, body condition score (BCS), DM intake (DMI) and health (calving score, metritis and mastitis) were recorded over the study period. Milk samples were collected on D15 and D60 post-calving for analyses of casein, Na+ and K+ contents and metalloprotease activity. Milk leukocytes and milk mammary epithelial cells (mMECs) were purified and counted. The viability of mMECs was assessed, together with their activity, through an analysis of gene expression. At the same time points, peripheral blood mononuclear cells (PBMCs) were purified and counted. Using genomic DNA extracted from PBMCs, mMECs and milk leukocytes, we assessed global DNA methylation (Me-CCGG) to evaluate the epigenetic imprinting associated with the µ-nutrient-supplemented diet. The µ-nutrient supplementation increased BCS and BW without modifying DMI or milk yield and composition. It also improved calving condition, reducing the time interval between calving and first service. Each easily collectable cell type displayed a specific pattern of Me-CCGG with only subtle changes associated with lactation stages in PBMCs. In conclusion, the response to the µ-nutrient supplementation improved the body condition without alteration of global epigenetic status in dairy cows.

Effects of an 8-Week Dairy Production Medicine Course on Veterinary Student Self-Confidence and Perceptions of Knowledge and Skills Used by Dairy Veterinarians

The 8-week dairy production medicine course at the National Center of Excellence in Dairy Production Medicine Education for Veterinarians is designed to equip senior veterinary students with the knowledge and skills needed to serve the dairy industry. Course developers identified 59 topics of importance for dairy production medicine veterinarians. Students (N = 50) were surveyed before and after the course to determine their perceptions of (a) the importance of the 59 topics for their intended positions and (b) their knowledge and skill in those areas. We expected the course to affirm or strengthen perceptions of importance and increase confidence. Students rated 57 of the topics as moderately or very important before the course. Ratings were unchanged (56 topics) or increased (3 topics) after the course. Before the course, students believed they had a lot of knowledge and skill in just one area: animal behavior and handling. At the end of the course, students believed they had a lot of knowledge and skill in 21 areas; confidence ratings were higher for 47 of the 59 topics. Alumni were surveyed 1-2 years after graduation to determine the importance of the 59 topics to their positions, their impressions about how well the course prepared them in those areas, and whether they referred back to course materials. Feedback was used to adjust the course. The topics alumni rated as most important were similar to those students predicted would be most important. Seventy-five percent of alumni used the course website as a resource in practice.

Review: Environmental impact on early embryonic development in the bovine species

Assisted reproduction techniques (ARTs) provide access to early stage embryos whose analysis and assessment deliver valuable information. The handling of embryos, including the in vitro production of bovine embryos, is a rapidly evolving area which nonetheless exposes the embryos to unnatural conditions for a period of time. The Fallopian tube provides innumerable quantitative and qualitative factors, all of which guarantee the successful development of the embryo. It is well known that the Fallopian tube can be bypassed, using embryo transfer, resulting in successful implantation in the target recipient animal and the birth of calves. However, the question arises as to whether such circumvention has a negative impact on the embryo during this sensitive development period. First crosstalk between the embryo and its environment confirms mutual recognition activities and indicate bilateral effects. Nowadays, in vitro production of bovine embryos is a well-established technology. However, it is still evident that in vitro generated embryos are not qualitatively comparable to embryos obtained ex vivo. To counteract these differences, comparative studies between in vitro and ex vivo embryos are advantageous, as embryos grown in their physiological environment can provide a blueprint or gold standard against which to compare embryos produced in vitro. Attempts to harness the bovine oviduct were sometimes very invasive and did not result in wide acceptance and routine use. Long-term development and refinement of transvaginal endoscopy for accessing the bovine oviduct has meanwhile been routinely applied for research as well as in practice. Comparative studies combining in vitro development with development in the cattle oviduct revealed that the environmental conditions to which the embryo is exposed before activation of the embryonic genome can have detrimental and lasting effects on its further development. These effects are manifested as deviations in gene expression profiles and methylation signatures as well as frequency of whole chromosomal or segmental aberrations. Furthermore, it was shown that hormonal superstimulation (multiple ovulation and embryo transfer), varying progesterone concentrations as well as metabolic disorders caused by high milk production, markedly affected embryo development in the postpartum period. Assisted reproductive techniques that allow the production and handling of extra numbers of generated embryos promise to have a very high impact on scientific and practical application. Any influence on the early embryonic life, both in animals and in vitro, is accompanied by a sensitive change in embryonic activity and should be assessed in vivo on the basis of physiological conditions before being used for ART.

Notice of RETRACTION: Changes in rumen fermentation, bacterial community, and predicted functional pathway in Holstein cows with and without subacute ruminal acidosis during the periparturient period

The authors have elected to retract this paper in accordance with the following points. The article as written contains misleading information and omits important details. Cows in this study were assigned to groups based on the current definition of subacute ruminal acidosis; they were housed on two different farms and fed two different sets of rations in this study. However, multiple farms were not described in the materials and methods and this was not accounted for in the statistical analysis as published. The diets shown in Table 1 were not actually fed to animals; rather, the proportions of ingredients listed represent an average of the two farms housing the cows. The authors regret the errors.

The potential interaction between body condition score at calving and dietary starch content on productive and reproductive performance of early-lactating dairy cows

Improving reproductive performance is one of the most important factors affecting the profitability of dairy herds. This study investigated the effect of feeding a high starch (HS) diet and body condition score (BCS) at calving on blood metabolites, fertility and ovarian function and milk production in Holstein dairy cows. One hundred seventy-four multiparous cows were fed common close-up and early lactation diets during the first 15 days in milk (DIM). Cows were randomly assigned to 1 of 2 experimental diets from 16 until 50 DIM (n = 87 per group); normal starch (228 g/kg diet DM; NS) or HS (270 g/kg diet DM; HS) diets. Each treatment group was further subdivided based on BCS at calving as normal BCS (BCS ⩽ 3.5; normal BCS (NBCS); n = 45) or high BCS (HBCS) (BCS ⩾ 3.75; HBCS; n = 42). A significant difference was detected for increased milk production (47.24 v. 44.55 kg/day) and decreased milk fat (33.93 v. 36.33 g/kg) in cows fed HS or NS, respectively. Plasma glucose and insulin concentrations were significantly higher in cows fed the HS compared to the NS diet. Diets significantly affected DIM at first artificial insemination (AI, 79.51 ± 3.83 v. 90.40 ± 3.83 days for cows fed HS and NS diets, respectively). High BCS groups had greater milk fat content and elevated plasma nonesterified fatty acids (NEFA), β hydroxybutyrate (BHB) and bilirubin concentrations. In general, feeding higher starch diets to normal BCS cows during the first 50 DIM improved productive and reproductive performance of early-lactating dairy cows.

In vivo model to study the impact of genetic variation on clinical outcome of mastitis in uniparous dairy cows

Background

In dairy herds, mastitis causes detrimental economic losses. Genetic selection offers a sustainable tool to select animals with reduced susceptibility towards postpartum diseases. Studying underlying mechanisms is important to assess the physiological processes that cause differences between selected haplotypes. Therefore, the objective of this study was to establish an in vivo infection model to study the impact of selecting for alternative paternal haplotypes in a particular genomic region on cattle chromosome 18 for mastitis susceptibility under defined conditions in uniparous dairy cows.

Results

At the start of pathogen challenge, no significant differences between the favorable (Q) and unfavorable (q) haplotypes were detected. Intramammary infection (IMI) with Staphylococcus aureus 1027 (S. aureus, n = 24, 96 h) or Escherichia coli 1303 (E. coli, n = 12, 24 h) was successfully induced in all uniparous cows. This finding was confirmed by clinical signs of mastitis and repeated recovery of the respective pathogen from milk samples of challenged quarters in each animal. After S. aureus challenge, Q-uniparous cows showed lower somatic cell counts 24 h and 36 h after challenge (P < 0.05), lower bacterial shedding in milk 12 h after challenge (P < 0.01) and a minor decrease in total milk yield 12 h and 24 h after challenge (P < 0.01) compared to q-uniparous cows.

Conclusion

An in vivo infection model to study the impact of genetic selection for mastitis susceptibility under defined conditions in uniparous dairy cows was successfully established and revealed significant differences between the two genetically selected haplotype groups. This result might explain their differences in susceptibility towards IMI. These clinical findings form the basis for further in-depth molecular analysis to clarify the underlying genetic mechanisms for mastitis resistance.

The complex relationship between welfare and reproduction in cattle

Using reproduction parameters as indicators for cattle welfare has limitations and, at best, these parameters should only be viewed as indirect indicators of welfare. On a farm level, measures such as fertility rates emphasize biological performance of the herd but fail to consider the welfare of individual animals. Even on an individual level, the relationship between reproductive effectiveness and animal welfare is complex. Good reproductive performance does not automatically signify good welfare, as domestication and targeted breeding programmes have led to prioritization of high productive and reproductive performance in most modern farm animal species. In this review, we synthesize literature regarding cattle husbandry, reproduction, welfare and their multidimensional relationships. We argue that practices such as artificial insemination or the use of sexed semen may provide potential welfare advantages as these practices reduce the risk of disease transmission and injury or enable selection of specific beneficial traits. Furthermore, they may offer a solution to current practices jeopardizing welfare, such as the management of surplus bull calves in the dairy industry. Conversely, the animals' ability to perform natural behaviours such as oestrous expression, an aspect arguably contributing to welfare, is often limited on commercial farms; this limitation is particularly evident in housing systems such as tie stalls where movement is restricted. Moreover, common management practices such as oestrus manipulation may lead to negative attitudes in citizens who often regard naturalness as important element of animal welfare.

Infrared thermography and feeding behavior of lambs fed increasing levels of safflower grains

ABSTRACT The objective was to evaluate the feeding behavior, physiological responses, and rumen heat emission of lambs fed with safflower grains. Eighteen lambs were randomly distributed in a completely randomized design. Safflower grain was added to the diets in the proportions of 0.0; 7.5 and 15%. The safflower grain did not change the patterns of eating, leisure, or rumination; however, it improved the efficiency of NDF ingestion, by 26%. The head temperature decreased by 1.5 ° C to include 7.5% safflower; and the rectal temperature decreased quadratically with the addition of safflower (39.5 and. 39.08 ° C). There was a linear trend of decreasing head temperature as the inclusion of safflower increased. The temperature of the eyeball decreased by 1.1 ° C when 7.5% of safflower DM was added to the diet and increased by 0.6 ° C when a 15% safflower was added. The ruminal temperature increased linearly for the addition of safflower (1.8 ° C). Safflower improves the efficiency of the use of NDF and the inclusion of 15% safflower can be used without effects on ingestive behavior. The head, eye, and left flank areas can be used; however, the left flank appears to be the best region for this type of study. Infrared thermography can be useful as a non-invasive assessment of lambs' diets.

Theoretical turnover rate of the rumen liquid fraction in dairy cows and its relationship to feed intake, rumen fermentation, and milk production

Ruminant animals are able to convert plant materials (grain and the human-indigestible portion of carbohydrates) to milk and meat. In this conversion, most of the plant materials are digested by rumen fermentation and are changed to short-chain fatty acids, microbial cells, and methane, which is released into the atmosphere. The relationships among feed, rumen fermentation, and milk production are poorly understood. Here we report a novel indicator of characteristics of rumen fermentation, theoretical turnover rate (TTOR) of the rumen liquid fraction. The TTOR was calculated from the presumed rumen volume (PRV) which is estimated by dividing the methane yield by the methane concentration of rumen fluid. The formula for the TTOR is: TTOR = PRV/body weight^0.75 . Our present analyses confirm that the TTOR as an indicator is capable of connecting feed, rumen fermentation, and milk production, because dry matter intake/TTOR showed a strong correlation with milk yield/TTOR. In addition, the TTOR may be related to ruminal pH, as we observed that the ruminal pH decreased as the TTOR increased. We propose that the TTOR is a factor characterizing rumen fermentation and a good indicator of the productivity of ruminants and dysbiosis of the rumen microbiome.

Revisiting Oxidative Stress and the Use of Organic Selenium in Dairy Cow Nutrition

In commercial animals production, productive stress can negatively impact health status and subsequent productive and reproductive performance. A great body of evidence has demonstrated that as a consequence of productive stress, an overproduction of free radicals, disturbance of redox balance/signaling, and oxidative stress were observed. There is a range of antioxidants that can be supplied with animal feed to help build and maintain the antioxidant defense system of the body responsible for prevention of the damaging effects of free radicals and the toxic products of their metabolism. Among feed-derived antioxidants, selenium (Se) was shown to have a special place as an essential part of 25 selenoproteins identified in animals. There is a comprehensive body of research in monogastric species that clearly shows that Se bioavailability within the diet is very much dependent on the form of the element used. Organic Se, in the form of selenomethionine (SeMet), has been reported to be a much more effective Se source when compared with mineral forms such as sodium selenite or selenate. It has been proposed that one of the main advantages of organic Se in pig and poultry nutrition is the non-specific incorporation of SeMet into general body proteins, thus forming an endogenous Se reserve that can be utilized during periods of stress for additional synthesis of selenoproteins. Responses in ruminant species to supplementary Se tend to be much more variable than those reported in monogastric species, and much of this variability may be a consequence of the different fates of Se forms in the rumen following ingestion. It is likely that the reducing conditions found in the rumen are responsible for the markedly lower assimilation of inorganic forms of Se, thus predisposing selenite-fed animals to potential Se inadequacy that may in turn compromise animal health and production. A growing body of evidence demonstrates that organic Se has a number of benefits, particularly in dairy and beef animals; these include improved Se and antioxidant status and better Se transfer via the placenta, colostrum, and milk to the newborn. However, there is a paucity in the data concerning molecular mechanisms of SeMet assimilation, metabolism and selenoprotein synthesis regulation in ruminant animals, and as such, further investigation is required.

A novel approach to study the bovine oviductal fluid proteome using transvaginal endoscopy

The oviduct provides the optimal micro milieu for early embryo development. However, accessing the bovine oviductal fluid in vivo for analysis is still challenging and therefore the oviductal fluid is usually collected post mortem. In the study presented here we introduce a novel approach to gain minimal invasive access to the bovine oviductal fluid proteome in vivo by transvaginal endoscopy at different stages of the estrous cycle. The first experiment aimed at transferring C4 derivatised magnetic beads to bind the oviductal fluid proteome in situ. Protein carrying beads were recovered by flushing the oviduct and proteins were eluted. In the second experiment a flushing solution was injected into and aspirated from the oviduct repeatedly. The flushing solution was centrifuged to separate the fluid from the cellular debris. Proteins were identified by nano-LC-MS/MS. Two different stages of the estrous cycle (Day 1 and Day 3) were analyzed in samples from 30 heifers. Both methods were applied successfully and in total, more than 3000 proteins were identified, so far representing the most comprehensive OF proteome published. This new minimal invasive approach to access the bovine oviductal fluid proteome facilitates future innovative experimental designs to study the role of the oviductal micro environment during early embryo development.

Diet-induced inflammation: From gut to metabolic organs and the consequences for the health and longevity of ruminants

Dietary shifts play an important role in decreased longevity in ruminant livestock. Ruminants evolved as cellulose fermenters adapt to fiber-rich diets. Instead, high-producing ruminants nowadays are commonly fed with grain-based diets to increase intake and productivity. Such diets, however, trade off the health of the animal. One negative aspect of such feeding is related to elevated levels of bacterial endotoxin (lipopolysaccharide, LPS) in the gut lumen and the likelihood of LPS translocation across the gut causing systemic and local (tissue) inflammation with consequences for production and longevity. However, the view for toxicity of gut LPS is oversimplified, overlooking the physicochemistry of LPS and the translocation route that determine the fate and immune reactive activity of LPS within the host. The barrier and defensive mechanisms of rumen morphology and intestinal mucus are understated. LPS cross the epithelial barrier paracellularly through impaired tight-junction and transcellularly through receptor-mediated transcytosis and the lipoprotein pathway transporting lipids. The lipoprotein pathway delivers LPS to the circulation before reaching the liver for detoxification and is believed to be the major natural route of gut LPS translocation at least in non-ruminants. Ruminant research has focused on endotoxemia and systemic inflammation but with little success and conflicting results, not to mention that low-grade inflammation is not easy to detect. In fact, LPS in the circulation must be effectively removed to avoid an adverse effect of rising level of LPS in the circulation. Circulating LPS could be transported towards target tissues in various organs, leading to local inflammation and altered metabolic activity in the tissues. Therefore, it might be feasible to capture tissue inflammation, especially in the metabolic organs including the liver, adipose tissues, and mammary gland. The present review gathers research updates and presents a comprehensive view of the physicochemical properties and bioactivity of LPS and the possibilities of translocation as well as other possible fate of LPS at each gut site in ruminants. Furthermore, we describe the involvement of three key metabolic organs including the liver, adipose tissue, and mammary gland in response to gut-derived LPS that lead to inflammation in the tissue posing consequences for the health and longevity of dairy cows.

Effects of a combination of plant bioactive lipid compounds and biotin compared with monensin on body condition, energy metabolism and milk performance in transition dairy cows

The aim of this study was to test whether a combination of plant bioactive lipid compounds (also termed ‘essential oils’) and biotin (PBLC+B) could decrease the mobilization of body reserves and ketosis incidence in postpartum dairy cows. We compared non-supplemented control (CON) cows with cows receiving monensin (MON) as a controlled-release capsule at d -21, and with cows receiving PBLC+B from day (d) -21 before calving until calving (Phase 1) and further until d 37 after calving (Phase 2), followed by PBLC+B discontinuation from d 38 to d 58 (Phase 3). The PBLC+B cows had higher body weight and higher back fat thickness than CON cows and lesser body weight change than MON and CON cows in Phase 3. Body condition score was not different among groups. Milk protein concentration tended to be higher on the first herd test day in PBLC+B vs. CON cows. Milk fat concentration tended to be highest in PBLC+B cows throughout Phases 2 and 3, with significantly higher values in PBLC+B vs. MON cows on the second herd test day. Yields of energy-corrected milk were higher in PBLC+B vs. CON and MON cows in Phase 2 and higher in PBLC+B and MON cows vs. CON cows in Phase 3. The incidence of subclinical ketosis was 83%, 61% and 50% in CON, PBLC+B and MON cows, respectively, with lower mean β-hydroxybutyrate values in MON than in PBLC+B cows in Phase 1 prepartum. The serum triglyceride concentration was higher in PBLC+B vs. CON cows on d 37. No differences were observed in serum glucose, urea, non-esterified fatty acids, cholesterol and bilirubin concentrations. Aspartate transaminase and γ-glutamyltranspeptidase but not glutamate dehydrogenase activities tended to be highest in MON and lowest in PBLC+B in Phase 2. We conclude that PBLC+B prevent body weight loss after parturition and are associated with similar ketosis incidence and partly higher yields of energy-corrected milk compared to MON supplementation of dairy cows.

Microanatomy of the digestive tract, hooves and some visceral organs of addax antelope (Addax nasomaculatus) following a concentrate or forage feeding regime

Subacute ruminal acidosis is a common disease in captive non-domesticated ruminants and is mainly diagnosed by rumen fluid pH and rumen histology. Furthermore, differences in ruminant gastrointestinal histology have been hypothesized to correlate with the browser-grazer continuum. Twelve surplus addax antelope (Addax nasomaculatus) were divided into two groups, fed either their usual diet, consisting of a concentrate feed with a limited amount of hay, or a diet of unlimited hay only, for 3 months. After culling, descriptive and morphometric histology and pH measurements were compared between groups. Significant variations in cellular subpopulations were noted between groups, with roughage-fed individuals presenting primarily with balloon cells of the Stratum corneum and living layer cell vacuolization, whereas parakeratosis and intermediate-type cells were more frequent in the concentrate-fed group. Lesions typical of subacute ruminal acidosis were significantly more pronounced in concentrate-fed individuals. Ruminal pH measurements did not differ significantly, but were more consistent in forage-fed individuals, indicating a more stable reticuloruminal environment. The results indicate that ruminal histology may be more appropriate in assessing ruminal health compared to a single post-mortem pH measurement. It is proposed that Stratum corneum balloon cells may indicate cell maturation and not, as previously assumed, hyperfunction. Concentrate-fed individuals scored higher on the presence of inflammatory cells on hoof corium histology. The study further emphasizes the adaptability of ruminant digestive tract microanatomy in adult animals even after a short period of time and the positive effects an increased roughage diet may have in populations of captive grazing ruminants.