Metabolic Control of Feed Intake

Variation in protein metabolism biomarkers during the transition period and associations with health, colostrum quality, reproduction, and milk production traits in Holstein cows

The aims of this study were to assess (1) the variation of protein metabolism biomarkers and factors affecting them during the transition period, (2) the association of each biomarker with skeletal muscle reserves and their changes, and (3) the association of these biomarkers with postpartum health, colostrum quality, reproduction, and milk production. For this purpose, 238 multiparous Holstein cows from 6 herds were used in a prospective cohort study. Plasma concentrations of 3-methylhistidine (3-MH) and 1-methylhistidine (1-MH) and serum concentrations of total protein (TP), albumin (ALB), urea nitrogen (BUN), and creatinine (SCR) were determined for each cow at -21, -7, 7, 21, and 28 d relative to calving. Clinical diseases were recorded during the first 28 d postcalving, and presence of subclinical ketosis (scKET) was investigated at 7 and 21 d. Colostrum quality was estimated by Brix refractometry. Reproduction data by 150 d in milk (DIM) and milk production records were also available. Linear mixed models including the fixed effects of time point, herd, parity, body condition score (-21 d), duration of dry period and postparturient diseases were fitted to assess the variation in each biomarker's concentration. The association between the biomarkers' concentration during the prepartum period with the odds for each postparturient disease and for a combined trait (CD_1-28), defined as the presence of at least one clinical condition during the first 28 d after calving, were assessed with separate binary logistic models for time points -21 d and -7 d. The relationship of each biomarker's concentration with longissimus dorsi thickness (LDT) and the changes in LDT (ΔLDT) was assessed with pairwise correlations. Separate general linear models were used to assess the association of each biomarker with colostrum Brix values and milk production traits. Finally, the associated hazard for first artificial insemination (AI) and for pregnancy by 150 DIM (PREG_150DIM) was assessed with Cox proportional hazard models, whereas odds for pregnancy to the first AI (PREG_1stAI) were assessed with binary logistic models. The level of 3-MH was affected mainly by herd, time points, and their interaction. Higher 3-MH was associated with increased odds for metritis and CD_1-28, increased hazard for PREG_150 DIM and with increased milk production. 1-Methylhistidine was affected mainly by herd, scKET and occurrence of displaced abomasum. Higher 1-MH was associated with better colostrum quality, increased odds for scKET, increased hazard for first AI by 150 DIM and with decreased milk production. Both 3-MH and 1-MH were weakly to moderately negatively correlated with LDT and moderately to strongly negatively correlated with ΔLDT at the corresponding time periods. Additionally, higher TP was associated with increased odds for metritis and CD_1-28 and increased milk production, while higher ALB was associated with increased odds for scKET and increased milk production. Moreover, higher BUN was associated with decreased odds for scKET, increased odds for PREG_1stAI and increased milk production. Higher SCR was associated with decreased odds for retained fetal membranes, metritis, and CD_1-28. Periparturient protein metabolism is significantly associated with postpartum health, colostrum quality, reproduction, and milk production; mechanisms involved require further investigation.

Farm-level risk factors associated with increased milk β-hydroxybutyrate and hyperketolactia prevalence on farms with automated milking systems

The objectives of this study were to determine the farm-level hyperketolactia (HKL) prevalence, as diagnosed from milk β-hydroxybutyrate (BHB) concentration, on dairy farms milking with an automatic milking system (AMS) and to describe the farm-level housing, management, and nutritional risk factors associated with increased farm-average milk BHB and the within-herd HKL prevalence in the first 45 DIM. Canadian AMS farms (n = 162; eastern Canada n = 8, Quebec n = 23, Ontario n = 75, western Canada n = 55) were visited once between April to September 2019 to record housing and herd management practices. The first test milk data for each cow under 45 DIM were collected, along with the final test of the previous lactations for all multiparous cows, from April 1, 2019 to September 30, 2020. The first test milk BHB was then used to classify each individual cow as having HKL (milk BHB ≥ 0.15 mmol/L) at the time of testing. Milk fat and protein content, milk BHB, and HKL prevalence were summarized by farm and lactation group (all, primiparous, and multiparous). During this same time period, formulated diets for dry and lactating cows, including ingredients and nutrient composition, and AMS milking data were collected. Data from the AMS were used to determine milking behaviors and milk production of each herd during the first 45 DIM. Multivariable regression models were used to associate herd-level housing, feeding management practices, and formulated nutrient composition with first test milk BHB concentrations and within-herd HKL levels separately for primiparous and multiparous cows. The within-herd HKL prevalence for all cows was 21.8%, with primiparous cows having a lower mean prevalence (12.2 ± 9.2%) than multiparous cows (26.6 ± 11.3%). Milk BHB concentration (0.095 ± 0.018 mmol/L) and HKL prevalence for primiparous cows were positively associated with formulated prepartum DMI and forage content of the dry cow diet while being negatively associated with formulated postpartum DMI, the major ingredient in the concentrate supplemented through the AMS, and the PMR-to-AMS concentrate ratio. However, multiparous cows' milk BHB concentration (0.12 ± 0.023 mmol/L) and HKL prevalence were positively associated with the length of the previous lactation, milk BHB at dry off, prepartum diet nonfiber carbohydrate content, and the major forage fed on farm, while tending to be negatively associated with feed bunk space during lactation. This is the first study to determine the farm-level risk factors associated with herd-level prevalence of HKL in AMS dairy herds, thus helping optimize management and guide diet formulation to promote the reduction of HKL prevalence.

Effects of offering free-choice hay for the first 5 days postpartum on productivity, serum inflammatory markers, gut permeability, and colon gene expression in fresh dairy cows

The objective of the present study was to evaluate the effects of offering free-choice hay to cows during the first 5 d immediately after calving on feed intake, milk yield, plasma metabolites, serum inflammatory markers, rumination, gut permeability, and colon gene expression. It was hypothesized that cows offered free-choice hay would have lower gut permeability, lower inflammation, and higher milk production, compared with cows not offered hay. Thirty-two multiparous cows were fed a closeup total mixed ration (TMR; 21.5% starch, 32.1% forage neutral detergent fiber [NDF] on a dry matter basis) until calving. In the postpartum period, all cows were fed a fresh cow TMR (26.8% starch and 23.4% forage NDF) from calving until 21 DIM, and were assigned randomly to receive 1 of 2 treatments as follows: (1) free-choice timothy hay (61.6% NDF; 9.6% crude protein), offered outside of the TMR in a separate manger, for the first 5 d postpartum (FCH; n = 20), or 2) no free-choice hay (NH; n = 12). The FCH cows tended to have lower serum haptoglobin concentration on d 3, compared with NH (0.95 vs. 1.52 mg/mL). Within the FCH group, cows with greater hay intake had a smaller increase in serum amyloid A from d 1 to 3 after calving (r = 0.37), and tended to have a smaller increase in serum haptoglobin concentration (r = 0.36). Cows in the FCH group had a lower ratio of starch intake (kg) to forage NDF intake (kg) on d 1 and 2, compared with NH (0.91 vs. 1.14 ± 0.03), and cows that had a lower starch:forage NDF ratio tended to have a smaller increase in serum haptoglobin concentration from d 1 to 3 after calving (r = 0.32). Cows in the FCH group had lower TMR dry matter intake (DMI; 15.0 vs. 17.1 ± 0.93 kg/d) and lower total DMI (TMR + hay DMI; 15.9 vs. 17.1 ± 0.87 kg/d), from d 1 to 5 when free-choice hay was offered, compared with NH. However, the hay treatment did not affect plasma energy metabolite concentration, gut permeability, colon gene expression, milk yield, rumination time, or change in body weight or body condition score. Overall, these findings suggest that offering free-choice hay for the first 5 d after calving may reduce serum inflammatory marker concentration, but milk yield may not increase, due to lower intake.

Associations among post-partum rumen fill and motility, subclinical ketosis and fertility in Holstein dairy cows

This prospective observational study aimed to investigate the association of rumen fill and motility in post-partum Holstein cows with their future reproductive performance and subclinical ketosis (SCK). The study population consisted of two independent data sets: the first (DS1) included 237 cows from 6 herds and the second one (DS2) 709 cows from 9 herds. Rumen Fill Score (RFS) was transformed into a 3 level-trait, representing very low, low and adequate dry matter intake, respectively. A binary Rumen Contraction Score (RCS) was defined as: 0: <2 contractions/2 min, impaired rumen motility and 1: ≥2 contractions/2 min, normal rumen motility. A combined binary trait based on RFS and RCS (RFCS) was also established, representing unsatisfactory and satisfactory rumen function. Three SCK traits were defined, based on 3 different thresholds, SCK_I: BHB≥1,000 mmol/L, SCK_II: BHB≥1,100 mmol/L and SCK_III: BHB≥1,200 mmol/L. Scores were assessed and blood samples collected on day 7 (DS1) or day 8 (DS2), postpartum. Kaplan-Meier survival analysis, multivariable Cox proportional hazards models and Generalized Linear Mixed Models were performed to evaluate the association of rumen and SCK traits with reproduction. Herd, parity, calving season and several postparturient diseases were also included as potential explanatory variables. Mean days from calving to pregnancy after the 1st artificial insemination (AI) and from calving to pregnancy (all AIs) were shorter for levels of rumen traits representing adequate DMI and normal rumen motility; in most cases these differences were statistically significant in both datasets. Cows with adequate DMI and normal rumen motility (only in DS2) had greater hazard (hazard ratio [HR] = 1.84 and 1.61, for RFS and RFCS, respectively) and odds (odds ratio [OR] = 2.49 and 1.98, for RFS and RFCS, respectively) for pregnancy at 1st AI. Assessment of the association of examined rumen traits with hazard and odds for pregnancy at all AIs yielded statistically significant results in both datasets. For RFS, RCS and RFCS, HRs ranged from 1.57 to 3.31 and ORs from 1.95 to 4.83. No statistically significant associations with hazard and odds for pregnancy at 1st or all AIs were detected, for any of the 3 SCK traits, in either dataset. Overall, the combined RFCS trait constantly identified more than twice the number of cows with future reproductive problems than a positive SCK blood test.

Invited Review: Increasing Milk Yield and Negative Energy Balance: A Gordian Knot for Dairy Cows?

The continued increase in milk production during the last century has not been accompanied by an adequate dry matter intake (DMI) by cows, which therefore experience a negative energy balance (NEB). NEB is low and of minor importance at low milk yield (MY), such as for the nutrition of one calf, and under these circumstances is considered "natural". MY and low DMI around parturition are correlated and are the reason for the genetic correlation between increasing MY and increasing NEB up to 2000 MJ or more for 2-3 months postpartum in high-genetic-merit dairy cows. The extension and duration of NEB in high-producing cows cannot be judged as "natural" and are compensated by the mobilization of nutrients, particularly of fat. The released non-esterified fatty acids (NEFAs) overwhelm the metabolic capacity of the cow and lead to the ectopic deposition of NEFAs as triglycerides (TGs) in the liver. The subsequent lipidosis and the concomitant hampered liver functions cause subclinical and clinical ketosis, both of which are associated with "production diseases", including oxidative and endoplasmatic stress, inflammation and immunosuppression. These metabolic alterations are regulated by homeorhesis, with the priority of the physiological function of milk production. The prioritization of one function, namely, milk yield, possibly results in restrictions in other physiological (health) functions under conditions of limited resources (NEB). The hormonal framework for this metabolic environment is the high concentration of growth hormone (GH), the low concentration of insulin in connection with GH-dependent insulin resistance and the low concentration of IGF-1, the so-called GH-IGF-1 axis. The fine tuning of the GH-IGF-1 axis is uncoupled because the expression of the growth hormone receptor (GHR-1A) in the liver is reduced with increasing MY. The uncoupled GH-IGF-1 axis is a serious impairment for the GH-dependent stimulation of gluconeogenesis in the liver with continued increased lipolysis in fat tissue. It facilitates the pathogenesis of lipidosis with ketosis and, secondarily, "production diseases". Unfortunately, MY is still increasing at inadequate DMI with increasing NEB and elevated NEFA and beta-hydroxybutyric acid concentrations under conditions of low glucose, thereby adding health risks. The high incidences of diseases and of early culling and mortality in dairy cows are well documented and cause severe economic problems with a waste of resources and a challenge to the environment. Moreover, the growing public concerns about such production conditions in agriculture can no longer be ignored.

Symposium review: Integrating the control of energy intake and partitioning into ration formulation

Energy intake and partitioning are determined by many interacting factors and their prediction is the Achilles' heel of ration formulation. Inadequate energy intake can limit milk yield and reproductive performance, whereas excessive energy intake will increase body condition, increasing the risk of health and reproductive issues in the subsequent lactation. Ration composition interacts with the physiological state of cows, making it difficult to predict DMI and the partitioning of energy accurately. However, understanding the factors controlling these allows us to devise grouping strategies and manipulate rations to optimize energy intake through lactation. Eating is controlled by the integration of signals in brain feeding centers. Ration composition affects DMI of cows via signals from ruminal distention and the hepatic oxidation of fuels. Dairy cow rations must contain a minimal concentration of relatively low-energy roughages for proper rumen function, but signals from ruminal distension can limit DMI when the drive to eat is high. Signals from the hepatic oxidation of fuels likely dominate the control of DMI in the peripartum period when cows are in a lipolytic state and later in lactation when signals from distension diminish. Therefore, the effects of the ration on DMI vary with the physiological state of the animal. Furthermore, they interact with environmental stressors such as social (e.g., overcrowding) and thermal stress. The objective of this article is to discuss the effects of ration composition on energy intake and partitioning in lactating cows and how they can be manipulated to optimize productive performance.

Symposium review: The impact of absorbed nutrients on energy partitioning throughout lactation

Most nutrition models and some nutritionists view ration formulation as accounting transactions to match nutrient supplies with nutrient requirements. However, diet and stage of lactation interact to alter the partitioning of nutrients toward milk and body reserves, which, in turn, alters requirements. Fermentation and digestion of diet components determine feeding behavior and the temporal pattern and profile of absorbed nutrients. The pattern and profile, in turn, alter hormonal signals, tissue responsiveness to hormones, and mammary metabolism to affect milk synthesis and energy partitioning differently depending on the physiological state of the cow. In the fresh period (first 2 to 3 wk postpartum), plasma insulin concentration and insulin sensitivity of tissues are low, so absorbed nutrients and body reserves are partitioned toward milk synthesis. As lactation progresses, insulin secretion and sensitivity increase, favoring deposition instead of mobilization of body reserves. High-starch diets increase ruminal propionate production, the flow of gluconeogenic precursors to the liver, and blood insulin concentrations. During early lactation, the glucose produced will preferentially be used by the mammary gland for milk production. As lactation progresses and milk yield decreases, glucose will increasingly stimulate repletion of body reserves. Diets with less starch and more digestible fiber increase ruminal production of acetate relative to propionate and, because acetate is less insulinogenic than propionate, these diets can minimize body weight gain. High dietary starch concentration and fermentability can also induce milk fat depression by increasing the production of biohydrogenation intermediates that inhibit milk fat synthesis and thus favor energy partitioning away from the mammary gland. Supplemental fatty acids also impact energy partitioning by affecting insulin concentration and insulin sensitivity of tissues. Depending on profile, physiological state, and interactions with other nutrients, supplemental fatty acids might increase milk yield at the expense of body reserves or partition energy to body reserves at the expense of milk yield. Supplemental protein or AA also can increase milk production but there is little evidence that dietary protein directly alters whole-body partitioning. Understanding the biology of these interactions can help nutritionists better formulate diets for cows at various stages of lactation.

Symposium review: Fueling appetite: Nutrient metabolism and the control of feed intake

Conceptual models developed over the past century describe 2 key constraints to feed intake (FI) of healthy animals: gut capacity and metabolic demand. Evidence that greater energy demands (e.g., greater milk production) drive a corresponding increase in caloric intake led to the dominant concept that animals "eat to energy requirements." Although this model provides reasonable initial estimates of FI, it lacks a proposed physiological basis for the control system, does not consider nutrient constraints beyond energy, and fails to explain differential energy intake responses to different fuels. To address these gaps, research has focused on mechanisms for sensing nutrient availability and providing feedback to hypothalamic centers that integrate signals to control feeding behavior. The elimination of FI response to certain nutrients by vagotomy suggests that peripheral tissues play a role in nutrient sensing. These findings and the central role of the liver in metabolic flux led to the development of the hepatic oxidation theory (HOT). According to the HOT, liver energy charge is the regulated variable that induces dietary intake changes and consequently affects whole-body energy balance. Evidence in support of HOT includes associations between hepatic energy charge and meal patterns, increased FI in response to phosphate trapping, and reduced FI in response to phosphate loading. In accordance with the HOT, infusion studies in dairy cattle have consistently demonstrated that providing fuels that either oxidize or stimulate oxidation in the liver decreases FI and energy intake to a greater extent than fuels that bypass the liver. Importantly, this holds true for glucose, which is readily oxidized by nerve cells, but is rarely taken up by the bovine liver. Although the brain integrates multiple signals including those related to gastric distention and illness, the HOT provides a physiological framework for understanding the dominant role the liver likely plays in sensing short-term energy status. Understanding this model provides insights into how to use or bypass the regulatory system to manage FI of animals.

Impacts of stress-induced inflammation on feed intake of beef cattle

Livestock animals are often exposed to unavoidable stressful situations during their productive life that triggers stress-induced inflammatory responses, which are known to influence their nutrient requirements and feed intake. Decreased growth performance and immunocompetence of stressed livestock are often the main consequence of reduced feed intake. Because feed intake is usually reduced in animals experiencing stress conditions, concentrations of certain nutrients in the diets typically need to be increased to meet the requirements of the animals. Therefore, understanding the mechanisms that control feed intake in animals experiencing stress-induced inflammation is essential for increasing intake, milk or meat production, feed efficiency, and animal health. This review highlights the hormones regulating feed intake in ruminants and how stress-induced inflammation affect these hormones at local and systemic levels. The mechanism of feed intake regulation in ruminants is extremely complex and involves multiple controls. The liver is an important sensor of energy status in animals under homeostatic conditions, which transmits signals to brain feeding centers that modulate appetite. However, the physiologic consequences associated with different stressors will rearrange the hierarchy of mechanisms controlling feed intake compared to animals under homeostatic conditions, and other tissues (e.g., intestines), systems (e.g., endocrine and lymphatic) hormones (e.g., leptin and ghrelin) will directly affect intake regulation during stress and inflammatory conditions. It is suggested that the immune system can interact with the central nervous system to modulate feed intake. As example, stress events elicit numerous stressors that increase circulating proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-8, and acute-phase proteins (APP), and the magnitude of these responses are negatively correlated with feed intake. A direct effect of these cytokines on rumen microbial fermentation and intestinal barrier function was also reported and might indirectly affect intake regulation in ruminants. This review describes the main hormones and proinflammatory cytokines involved in stress-induced inflammation and how they can directly or indirectly affect intake regulation in ruminants. Understanding the mechanisms controlling feed intake in ruminants will help producers to implement management and feed strategies to optimize productivity and profitability in stressed livestock species.

Skeletal muscle and adipose tissue reserves and mobilisation in transition Holstein cows: Part 2 association with postpartum health, reproductive performance and milk production

The aim of this study was, for the first time, to simultaneously assess the association of skeletal muscle and subcutaneous fat reserves and their mobilisation, measured by ultrasonography, with the incidence of specific postparturient health, reproduction, and milk production traits. For this purpose, ultrasound measurements of longissimus dorsi thickness (LDT) and backfat thickness (BFT) from 238 multiparous cows from 6 dairy farms were obtained at 6 time points during the transition period (from 21 days pre- to 28 days postpartum). In each case, LDT and BFT measurements at each time point and LDT and BFT mobilisation variables at each study period were assessed simultaneously. Cases of specific clinical postparturient diseases and subclinical ketosis were recorded. An additional disease trait was used, defined as the presence or absence of at least one clinical condition after calving (CD_1-28). The associated disease odds with LDT/BFT variables were assessed with binary logistic regression models. The associated hazard for 1st artificial insemination (AI) and for pregnancy by 150 days-in-milk (PREG_150DIM) was assessed with Cox proportional hazard models. Moreover, binary logistic models were used to assess the associated odds for pregnancy to 1^stAI (PREG_1^stAI). Finally, association with 30d, 100d and 305d milk yield was assessed with linear regression models. Increased muscle depth during transition was negatively associated with odds for metritis and CD_1-28, while associations with odds for subclinical ketosis were inconclusive. Moreover, increased LDT reserves were associated with greater hazard for 1st AI by 150 days-in-milk, but results were inconclusive regarding odds for PREG_1^stAI. Increased LDT mobilisation was associated with increased odds for metritis. Increased BFT reserves were positively associated with odds for metritis, CD_1-28 and subclinical ketosis and with decreased hazard for PREG_150DIM. Increased BFT mobilisation was associated with increased odds for subclinical ketosis and with decreased odds for PREG_1^stAI and decreased hazard for PREG_150DIM. Cows with moderate BFT reserves performed better. Finally, increased BFT mobilisation during -21d to -7d from parturition was associated with less milk by 30d and 100d. On the contrary, increased BFT mobilisation during -7d to 7d was associated with more milk by 305d. Metabolism of muscle and fat tissue during transition period was differently associated with different postparturient health, reproduction and milk production traits. In general, greater muscle mass and moderate fat reserves with limited muscle and fat mobilisation were associated with better performance.

The Response of Fecal Microbiota and Host Metabolome in Dairy Cows Following Rumen Fluid Transplantation

Rumen fluid transplantation (RFT) has been used to rebuild rumen bacterial homeostasis, reshape rumen function, and restore rumen fermentation, whereas the effect of RFT on fecal microbiota and host metabolism in cows remains poorly understood. In our study, a combination of 16S rRNA sequencing and serum non-targeted metabolomics was performed to investigate the response of fecal microbiota and serum metabolome in dairy cows following RFT. Twenty-four prepartum dairy cows were randomly assigned to 3 groups (n = 8) for infusion of either saline (Con), fresh rumen fluid (FR), or sterilized rumen fluid (SR) after calving. Fourteen days after calving, fecal microbiota and serum metabolome were analyzed. The sequencing data of fecal samples revealed no changes in alpha diversity and relative abundance of dominant genera such as Ruminococcaceae UCG-005, Rikenellaceae RC9 gut and Eubacterium coprostanoligenes. However, the other genus level taxa, such as Eubacterium oxidoreducens, Anaerorhabdus furcosa, Bacillus and Selenomonas, showed distinct changes following RFT. Serum metabolome analysis showed that FR or SR infusion affected amino acids metabolism, bile acids metabolism and fatty acids metabolism (including linoleic acid, oleic acid and palmitic acid). Furthermore, correlation analysis showed that taxa from genera Clostridiales were positively correlated with metabolites involved in tryptophan and bile acid metabolisms, such as OTU1039 from genera unclassified o_Clostridiales was positively correlated to indoleacetic acid and taurolithocholic acid. These results suggest that RFT altered the composition of the fecal microbiota and modulated microbial metabolic pathways, which is vital for the development and safety assessment of rumen microbial intervention strategies.

Feasibility of Supplying Ruminally Protected Lysine and Methionine to Periparturient Dairy Cows on the Efficiency of Subsequent Lactation

The objective of this study was to evaluate the effects of supplying ruminally protected Lys (RPL) and ruminally protected Met (RPM) to transition cows' diets on the efficiency of subsequent lactation. A total of 120 prepartum Holstein cows were assigned into four treatments blocked by the anticipated calving date, previous lactation milk yield, number of lactations, and body condition score and fed either RPL, RPM, or the combination (RPML) or control diet (CON) throughout the transition period (3 weeks before till 3 weeks after calving). From 22 to 150 days in milk (DIM), all animals (100 cows) were fed a combination of RPM and RPL (0.17% RPM and 0.41% RPL of DM; n = 25 cows/treatment) as follows; CON–RPML, RPM–RPML, RPL–RPML, and RPML–RPML. Milk production and dry matter intake (DMI) were measured daily; milk and blood samples were taken at 21, 30, 60, 90, 120, and 150 DIM. Supplemented amino acids (AA) were mixed with the premix and added to the total mixed ration during the experiment. DMI (p &lt; 0.001) and energy-corrected milk (ECM, p = 0.04) were higher for cows that were fed RPML–RPML than other cows. Compared with CON–RPML, yields of milk total protein, lactose, and nitrogen efficiency were increased (p &lt; 0.01), whereas milk urea nitrogen (MUN; p = 0.002) was decreased for other treatments. However, supplemental AA did not affect milk lactose percentage, fat yield, feed efficiency, or serum total protein concentration (p &gt; 0.10). Transition cows that consumed AA had a greater peak of milk yield (p &lt; 0.01), as well as quickly reached the peak of milk (p &lt; 0.004). There were differences in β-hydroxybutyrate concentration during the early lactation, with a lower level for AA groups (p &lt; 0.05), and the difference faded with the progression of lactation (p &gt; 0.10). Fertility efficiency as measured by pregnancy rate was improved by supplemental AA during the perinatal period (p &lt; 0.05). In conclusion, transition cows consumed RPM and RPL, increased post-calving DMI, milk production, milk protein yield, nitrogen efficiency, and improved fertility performance.

Balancing Trade-Offs in Milk Production by Making Use of Animal Individual Energy Balancing

Traditionally, the energy supply of dairy cows is based on the average performance of the herd. Because this contradicts the great variation in requirements between individual animals, the objective of the present study was to quantify both the extent and consequences of variation in the relevant sub-variables used to calculate the energy balance (EB) on an individual animal basis. Total energy supply (TES) and requirements (TER) of 28 multiparous German Holstein dairy cows fed TMR with 7.0 MJ NEL were studied between the 2nd and 15th week after calving. TES, mainly influenced by DMI, increased from 100.1 (week 2) to 152.1 MJ NEL/d (week 15; p < 0.01). Weekly coefficients of variation (CV) ranged between 0.10 and 0.16 and were similar to the CV of DMI (0.09 to 0.17). TER, as the sum of energy requirement for maintenance (body weight) and production (milk yield), decreased from 174.8 (week 2) to 164.5 MJ NEL/d (week 15; p < 0.01) and CV varied between 0.16 (week 2) and 0.07 (week 11). EB increased from −74.8 (week 2) to −12.4 MJ NEL/d (week 15; p < 0.01) and CV varied from 0.32 (week 3) to 1.01 (week 10). The results indicate that calculating EB on an individual animal basis is a prerequisite to identify animals with an increased risk of failing to cope with their energy situation, which cause failure costs that drain the profit of affected cows.

Supplementing Ruminally Protected Lysine, Methionine, or Combination Improved Milk Production in Transition Dairy Cows

The objectives of this study were to evaluate the effects of dietary supplementation of ruminally protected lysine (RPL), or methionine (RPM), and their combination (RPML) on the production efficiency of transition cows. A total of 120 pre-partum multiparous Holstein cows were assigned to four treatments based on previous lactation milk production, days (d) of pregnancy, lactation, and body condition score (BCS). Cows were fed a basal diet [pre-calving: 1.53 Mcal/kg dry matter (DM) and post-calving: 1.70 Mcal/kg DM] with or without supplemental ruminally protected amino acids (RPAA). Treatments were the basal diets without supplemental amino acids (CONTROL, n = 30), with supplemental methionine (RPM, pre-calving at 0.16% of DM and post-calving at 0.12% of DM, n = 30), with supplemental lysine (RPL, pre-calving at 0.33% of DM and post-calving at 0.24% DM, n = 30), and the combination (RPML, pre-calving at 0.16% RPM + 0.33% RPL of DM and post-calving at 0.12% RPM + 0.24 % RPL DM, n = 30). The dietary content of lysine was balanced to be within 6.157.2% metabolizable protein (MP)-lysine and that of methionine was balanced within 2.1-2.35% MP-methionine. Dry matter intake (DMI) was measured daily. Milk samples were taken on d 7, 14, and 21 days relative to calving (DRC), and milk yields were measured daily. Blood samples were taken on d -21, -14, -7 before expected calving and d 0, 7, 14, and 21 DRC. Data were analyzed using SAS software. There were significant Trt × time interactions (P < 0.01) for DMI pre- and post-calving period. The CON cows had lower DMI than RPM, RPL, and RPML, both pre-calving (P < 0.01) and post-calving periods (P < 0.01). Energy-corrected milk (P < 0.01), milk fat (P < 0.01), protein (P = 0.02), and lactose (P < 0.01) percentage levels were greater for RPM, RPL, and RPML cows compared to CON. Supplementing RPAA assisted in maintaining BCS post-calving than CON (P < 0.01). Blood concentrations of β-hydroxybutyrate decreased with RPM or RPL or the combination pre-calving (P < 0.01) and tended to decrease post-calving (P = 0.10). These results demonstrated that feeding RPL and RPM improved DMI and milk production efficiency, maintained BCS, and reduced β-hydroxybutyrate concentrations of transition cows.

Metabolic imbalances, hoof injuries, and metabolic profile of high-producing Holstein × Gir cowsshowing lameness

ABSTRACT: This study attempted to determine the associations between metabolic imbalances and lameness or hoof injuries in high-producing Holstein × Gir cows, and to determine whether the metabolic profile affects the occurrence of lameness. Eighty cows were followed from -60 to 60 days relative to calving and hoof injuries were reported on days -60, 7 and 60. Locomotion score (LS), body condition score (BCS), the concentrations of non-esterified fatty acids, β-hydroxybutyrate, glucose, cholesterol, albumin, total protein, blood urea nitrogen (BUN), calcium, phosphorus, and magnesium, and the activity of aspartate aminotransferase were determined at days -42, -21, -7, 0, 7, 21 and 42. The McNemar and Chi-square tests were used to compare frequencies of lameness and hoof injuries over time and to verify the associations between lameness, BCS, hoof injuries, and metabolic disorders. Two-way repeated measures ANOVA was used considering groups (non-lame × lame cows) and variations of BCS and metabolites over time. Lameness and hoof injuries increased between days -60 (20% and 66.3%) and 60 (44.7% and 98.6%). Excessive postpartum loss of BCS (P=0.017) and subclinical hypocalcemia (P=0.012) were associated with lameness on day 60. In general, the metabolic profile did not differ between lame and non-lame cows but cholesterol, albumin, BUN and magnesium concentrations were higher in non-lame cows. The postpartum decrease in BCS can affect the occurrence of lameness, and the metabolic profile of lame cows shows little difference from that of non-lame cows.

Effects of increasing calcium propionate in a finishing diet on dry matter intake and glucose metabolism in steers

The objective of this study was to determine if increasing propionate alters dry matter intake (DMI), glucose clearance rate, blood metabolites, insulin concentrations and hepatic gene expression in steers fed a finishing diet. Holstein steers (n = 15; BW = 243 ± 3.6 kg) were individually fed a finishing diet ad-libitum. Steers were allocated by body weight (BW) to receive: no Ca propionate (Control), 100 g/d Ca propionate (Low), or 300 g/d Ca propionate (High) in the diet. Orts were collected and weighed daily to determine DMI. Blood samples were collected on d 0, 7, and 21, and BW recorded on d 0, 14, and 28. An intravenous glucose tolerance test (IVGTT) was conducted on d 14 and 28 of the trial. Liver biopsies were collected on d 33 for gene expression analysis. Blood samples were analyzed for whole blood glucose and lactate, plasma non-esterified fatty acids (NEFA) and insulin concentrations. Data were analyzed using a mixed model with treatment, day and their interaction included, with day and minute as a repeated measure. The control treatment had greater (P < 0.01) DMI than low and high steers. Body weight was increased in control steers on d 14 and 28 compared to the steers receiving the High treatment (P = 0.03 for the interaction). Blood glucose concentrations tended (P = 0.09) to be higher on d 21 than d 0 and 7 but was not affected by treatment (P = 0.58). Plasma NEFA concentrations were lower (P = 0.05) for control steers than other treatments, and greater (P = 0.002) on d 0 than d 7 and 21. Blood lactate concentrations were greater (P = 0.05) on d 7, than d 0 and 21, but not affected by treatment (P = 0.13). High steers had greater plasma insulin concentrations in response to the IVGTT than steers on the other treatments (P = 0.001). There was no treatment (P ≥ 0.16) or day effect (P ≥ 0.36) on glucose peak, plateau, or clearance rate. High steers had greater expression of solute carrier family 16 member 1 (SLC16A1; P = 0.05) and tended to have greater hepatic expression of solute carrier family 2 member 2 (SLC2A2; P = 0.07). These data indicate that increased propionate may decrease DMI and insulin sensitivity.

Microbiome Clusters Disclose Physiologic Variances in Dairy Cows Challenged by Calving and Lipopolysaccharides

Dairy cows respond individually to stressful situations, even under similar feeding and housing conditions. The phenotypic responsiveness might trace back to their microbiome and its interactions with the host. This long-term study investigated the effects of calving, lipopolysaccharide (LPS)-induced inflammation, and l-carnitine supplementation on fecal bacteria and metabolites, dairy cow milk production, health, energy metabolism, and blood metabolites. Fifty-four multiparous Holstein dairy cows were examined over a defined period of life (168 days). The obtained data allowed a holistic analysis combining microbiome data such as 16S rRNA amplicon sequencing and fecal targeted metabolome (188 metabolites) with host parameters. The conducted analyses allowed the definition of three enterotype-like microbiome clusters in dairy cows which could be linked to the community diversity and dynamics over time. The microbiome clusters were discovered to be treatment independent, governed by Bifidobacterium (C-Bifi), unclassified (uncl.) Clostridiales (C-Clos), and unclassified Spirochaetaceae (C-Spiro). Animals between the clusters varied significantly in terms of illnesses, body weight, microbiome composition, and milk and blood parameters. C-Bifi animals were healthier and leaner with a less diverse but dynamic microbiome. C-Spiro animals were heavier, but the diversity of the static microbiome was higher. This pioneering study uncovered microbiome clusters in dairy cows, each contributing differently to animal health and productive performance and with a crucial role of Bifidobacterium. IMPORTANCE The health of dairy cows has to be carefully considered for sustainable and efficient animal production. The microbiome of animals plays an important role in the host's nutrient supply and regulation of immune functions. We show that a certain composition of the fecal microbiome, called microbiome clusters, can be linked to an animal's health at challenging life events such as calving and inflammation. Cows with a specific set of bacteria have coped better under these stressors than have others. This novel information has great potential for implementing microbiome clusters as a trait for sustainable breeding strategies.

An Exploration of the Effects of an Early Postpartum Intravenous Infusion with Carnosic Acid on Physiological Responses of Transition Dairy Cows

The objective of the present study was to evaluate the effects of an antioxidant and anti-inflammatory compound found in rosemary plants (Salvia rosmarinus) named carnosic acid during the transition period of dairy cows. From day 1 to 3 after calving, 16 multiparous Holstein cows received a daily intravenous infusion of either 500 mL of saline (NaCl 0.9%; Saline; n = 8) or carnosic acid at a rate of 0.3 mg/kg of BW supplied in 500 mL of saline (CA; n = 8). Blood samples were taken at –7, 2, 5, 7, 14, and 21 d relative to parturition, then analyzed for metabolites related to energy metabolism, muscle mass catabolism, liver function, inflammation, and oxidative stress. CA infusion tended to improve milk performance; however, DMI was unaffected by treatment. At 2 d relative to parturition, CA cows had lower blood concentrations of haptoglobin, paraoxonase, FRAP, and NO₂^– than saline cows. After treatment infusions, haptoglobin remained lower in CA cows than saline at 5 d relative to parturition. Our results demonstrate that carnosic acid promoted positive responses on inflammation and oxidative stress biomarkers and may promote beneficial effects on lactation performance in peripartal dairy cows.

Effects of prepartum dietary protein level and feed intake on postpartum lactation performance and feeding behavior of multiparous Holstein dairy cows

An experiment was conducted to determine the effects of low and high metabolizable protein (MP) diets when fed for ad libitum and controlled intake during the prepartum period on postpartum lactation performance and feeding behavior of dairy cows. Thirty-six multiparous Holstein cows were blocked by parity, expected calving date, and previous lactation milk yield at -21 d relative to expected calving and were randomly assigned to 1 of 4 close-up period dietary treatments providing low MP (LMP) or high MP (HMP) diets with controlled intake (CNI) or ad libitum intake (ALI). The concentrations of MP were 65 and 90 g/kg dry matter for LMP and HMP diets, respectively, whereas intake was controlled to supply 100 and 160% of the NRC (2001) energy requirements for CNI and ALI groups, respectively. The concentration of net energy for lactation (NE_L) in the treatment diets was 1.50 Mcal/kg. All cows were fed a similar lactation diet after calving (1.50 Mcal/kg of NE_L and 83.3 g/kg of MP). The HMP diet increased dry matter intake during the first 3 wk and tended to increase dry matter intake over the 9 wk of lactation. Meal size and eating rate increased in the ALI cows during the prepartum period. Meal frequency increased with the HMP diet during the postpartum period. Milk yield increased by 15.2% with the HMP diet over the 9 wk of lactation. The HMP diet increased energy-corrected milk (ECM) yield in CNI versus ALI cows, whereas the LMP diet increased ECM yield in ALI versus CNI cows over the 9 wk of lactation. The increase in ECM yield of LMP-ALI versus LMP-CNI cows was supported by greater body condition loss and serum β-hydroxybutyrate over the 9 wk of lactation. Taken together, these data indicate that prepartum controlled intake of a high protein diet can provide the benefits of both strategies.

Milk yield and composition in dairy cows with post-partum disorders

ABSTRACT This study aimed to determine the impact of different post-partum disorders on milk yield and composition. One hundred and fifteen Holstein cows from a commercial dairy farm located in the state of Rio Grande do Sul in southern Brazil were monitored up to 62 days post-partum. During this period, body condition score evaluation and animal clinical examination were conducted. Percentages of fat, protein, and lactose, as well as somatic cells score, were determined in milk samples. The AST activity and concentrations of NEFA, calcium, and BHBA, were analyzed in blood samples. The occurrence of clinical disorders was identified in 30 (26%) cows. Subclinical disorders were identified in 64 (56%) cows. Only 21 (18%) cows did not suffer any kind of disorder within the studied period. In this study, no significant differences were found in milk production, protein, and somatic cell count in clinical, subclinical, and healthy cows. Milk fat and the fat: protein quotient (F:P) were higher in cows with clinical disorders and the 6 to 21 days in milk, and lactose were lower in cows with clinical disorders and the 22 to 42 days in milk (P<0.05).

Relationships between energy balance during early lactation and cow performance, blood metabolites, and fertility: A meta-analysis of individual cow data

This study was designed to contribute to the understanding of the relationships between energy balance (EB) in early lactation [4 to 21 d in milk (DIM)] and fertility traits [interval to start of luteal activity (SLA), interval to first observed heat (FOH), and conception to first artificial insemination (AI)], and their associated relationships with cow performance and blood metabolites between 4 to 150 DIM. Individual cow data (488 primiparous and 1,020 multiparous lactations) from 27 experiments was analyzed. Data on cow performance, EB (on a metabolizable energy basis), and fertility traits were available for all cows, whereas milk progesterone data (to determine SLA) and periodic blood metabolite data were available for 1,042 and 1,055 lactations, respectively. Data from primiparous and multiparous cows were analyzed separately, with the data sets for the 2 parity groups divided into quartiles (Q1-Q4) according to the average EB during 4 to 21 DIM (EB range for Q1 to Q4: primiparous, -120 to -49, -49 to -24, -24 to -3, and -3 to 92 MJ/d, respectively: multiparous, -191 to -79, -79 to -48, -48 to -22, and -22 to 93 MJ/d, respectively). Differences between EB quartiles for production and fertility traits were compared. In early lactation (4 to 21 DIM), moving from Q1 to Q4 mean DMI and metabolizable energy intake increased whereas mean ECM decreased. During the same period, moving from Q1 to Q4 milk fat content, milk fat-to-protein ratio, and plasma nonesterified fatty acid and β-hydroxybutyrate concentrations decreased, whereas milk protein content and plasma glucose concentrations increased in both primiparous and multiparous cows. When examined over the entire experimental period (4 to 150 DIM), many of the trends in intakes and milk production remained, although the magnitude of the difference between quartiles was much reduced, whereas milk fat content did not differ between quartiles in primiparous cows. The percentage of cows with FOH before 42 DIM increased from Q1 to Q4 (from 46 to 72% in primiparous cows, and from 41 to 58% in multiparous cows). Interval from calving to SLA and to FOH decreased with increasing EB during 4 to 21 DIM, with these occurring 9.8 and 10.2 d earlier, respectively, in Q4 compared with Q1 (primiparous cows), and 7.4 and 5.9 d earlier, respectively, in Q4 compared with Q1 (multiparous cows). For each 10 MJ/d decrease in mean EB during 4 to 21 DIM, FOH was delayed by 1.2 and 0.8 d in primiparous and multiparous cows, respectively. However, neither days to first AI nor the percentage of cows that conceived to first AI were affected by daily EB during 4 to 21 DIM in either primiparous or multiparous cows, and this is likely to reflect a return to a less metabolically stressed status at the time of AI. These results demonstrate that interval from calving to SLA and to FOH were reduced with increasing EB in early lactation, whereas early lactation EB had no effect on conception to the first service.

Effect of uncouplers of oxidative phosphorylation on metabolism of propionate in liver explants from dairy cows

Our objective was to determine the effects of uncouplers of oxidative phosphorylation on the metabolism of propionate in liver tissue of dairy cows in the postpartum period. A total of 8 primiparous dairy cows were biopsied for liver tissue explants in 2 block-design experiments. Cows were 5.9 ± 2.8 (mean ± SD) days in milk, and the 2 experiments were run concurrently. Treatments for experiment 1 were 10 μM 2,4-dinitrophenol methyl ether (DNPME) or propylene carbonate (vehicle control). Treatments for experiment 2 were 5 mM sodium salicylate (SAL) or no treatment (control). Explants were incubated in 2.5 mM [¹³C₃]propionate with treatments and terminated after 0.5, 15, and 60 min of exposure to tracer. Treatment with DNPME had no effects on measured metabolites compared with control. Treatment with SAL increased total ¹³C% enrichment of succinate (3.03 vs. 2.45%), but tended to decrease total ¹³C% enrichment of fumarate (2.86 vs. 3.10%) and decreased total ¹³C% enrichment of malate (3.96 vs. 4.58%) compared with the control. Treatment with DNPME appeared to have no effects on hepatic propionate metabolism, and treatment with SAL may impair the succinate dehydrogenase reaction.

Addition of straw to the early-lactation diet: Effects on feed intake, milk yield, and subclinical ketosis in Holstein cows

This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle.

Altering the ratio of dietary palmitic and oleic acids affects nutrient digestibility, metabolism, and energy balance during the immediate postpartum in dairy cows

This article is the second from an experiment that determined the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on digestibility, production, and metabolic responses of dairy cows during the immediate postpartum. This article elaborates on the effect of these diets on nutrient digestibility, energy balance, and metabolism. Fifty-six multiparous cows were used in a randomized complete block design and randomly assigned to 1 of 4 treatments fed from 1 to 24 d in milk. The treatments were: (1) control (CON) diet not supplemented with fatty acids (FA); (2) diet supplemented with a FA blend containing 80% C16:0 and 10% cis-9 C18:1 (80:10); (3) diet supplemented with a FA blend containing 70% C16:0 and 20% cis-9 C18:1 (70:20); and (4) diet supplemented with a FA blend containing 60% C16:0 and 30% cis-9 C18:1 (60:30). The FA supplement blends were added at 1.5% of diet dry matter by replacing soyhulls in the CON diet. Three preplanned contrasts were used to compare treatment differences: (1) CON versus FA-supplemented diets, (80:10 + 70:20 + 60:30)/3; (2) the linear effect of cis-9 C18:1 inclusion in diets; and (3) the quadratic effect of cis-9 C18:1 inclusion in diets. The FA-supplemented diets increased digestibility of dry matter, neutral detergent fiber, 18-carbon FA, and total FA compared with CON. We observed a tendency for an interaction between treatment and time for the digestibility of 18-carbon and total FA because the difference in digestibility between CON and 60:30 treatments tended to increase over time. Increasing dietary cis-9 C18:1 increased linearly the digestibility of dry matter, neutral detergent fiber, 16-carbon, 18-carbon, and total FA. Interestingly, total absorbed FA was positively related to milk, milk fat yield, energy-corrected milk, plasma insulin, and albumin, and negatively related to plasma nonesterified FA (NEFA) and body weight loss. The FA-supplemented diets increased intake of digestible energy, metabolizable energy, and net energy for lactation compared with CON. Compared with CON, FA-supplemented diets increased milk energy output and tended to increase negative energy balance. Increasing dietary cis-9 C18:1 increased intake of digestible energy, metabolizable energy, and net energy for lactation. Although increasing dietary cis-9 C18:1 did not affect milk energy output and energy for maintenance, increasing dietary cis-9 C18:1 improved energy balance. Compared with CON, FA-supplemented diets increased plasma insulin, but we did not observe differences between CON and FA-supplemented diets for NEFA and albumin. Increasing cis-9 C18:1 in FA treatments linearly decreased plasma NEFA and tended to linearly increase insulin and β-hydroxybutyrate. During the carryover period, no treatment differences in blood metabolites were observed. Our results indicate that feeding FA supplements containing C16:0 and cis-9 C18:1 during the immediate postpartum period increased nutrient digestibility, energy intake, and milk energy output compared with a non-fat-supplemented control diet. Increasing dietary cis-9 C18:1 increased energy intake, reduced markers of body fat mobilization, and improved energy balance during the immediate postpartum.

Altering the ratio of dietary palmitic and oleic acids affects production responses during the immediate postpartum and carryover periods in dairy cows

The objectives of our study were to determine the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on production and metabolic responses of early-lactation dairy cows during the immediate postpartum period and to evaluate carryover effects of the treatment diets early in lactation. Fifty-six multiparous cows were used in a randomized complete block design and randomly assigned to 1 of 4 treatments (14 cows per treatment) fed from 1 to 24 d in milk (DIM). The treatments were: (1) control (CON) diet not supplemented with fatty acids (FA); (2) diet supplemented with a FA blend containing 80% C16:0 and 10% cis-9 C18:1 (80:10); (3) diet supplemented with a FA blend containing 70% C16:0 and 20% cis-9 C18:1 (70:20); and (4) diet supplemented with a FA blend containing 60% C16:0 and 30% cis-9 C18:1 (60:30). The FA supplement blends were added at 1.5% of diet DM by replacing soyhulls in the CON diet. All cows were offered a common diet from d 25 to 63 postpartum (carryover period) to evaluate carryover effects. Three preplanned contrasts were used to compare treatment differences: CON versus FA-supplemented diets (80:10 + 70:20 + 60:30)/3; the linear effect of cis-9 C18:1 inclusion in diets; and the quadratic effect of cis-9 C18:1 inclusion in diets. During the treatment period, FA-supplemented diets increased milk yield, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM) compared with CON. Compared with CON, FA-supplemented diets increased milk fat content, milk fat yield, yield of mixed FA, and tended to increase protein yield and lactose yield. Also, compared with CON, FA-supplemented diets tended to increase body condition score (BCS) change. A treatment by time interaction was observed for body weight (BW), due to 80:10 inducing a greater BW loss over time compared with other treatments. Increasing cis-9 C18:1 in FA treatments tended to linearly increase dry matter intake (DMI) but did not affect milk yield, 3.5% FCM, ECM, and the yields of milk fat, protein and lactose. Increasing cis-9 C18:1 in FA treatments linearly decreased milk fat content and milk lactose content. Also, increasing cis-9 C18:1 in FA treatments linearly decreased BW and BCS losses. During the carryover period, compared with CON, FA-supplemented diets tended to increase milk yield. Also, FA-supplemented diets increased 3.5% FCM, ECM, and milk fat yield, and tended to increase milk protein yield compared with CON. A treatment by time interaction was observed for BW due to 80:10 increasing BW over time compared with CON. Our results indicate that feeding FA supplements containing C16:0 and cis-9 C18:1 during the immediate postpartum period increased milk yield and ECM compared with a nonfat supplemented control diet. Increasing cis-9 C18:1 in the FA supplement increased DMI and reduced BW and BCS losses. Additionally, the fat-supplemented diets fed during the immediate postpartum period had a positive carryover effect during early lactation, when cows were fed a common diet.

Acute-phase protein α-1-acid glycoprotein is negatively associated with feed intake in postpartum dairy cows

α-1-Acid glycoprotein (AGP) is an acute-phase protein that may suppress dry matter intake (DMI), potentially by acting on the leptin receptor in the hypothalamus. Our objectives were to characterize plasma AGP concentration and associations with DMI during the transition period, and to determine the utility of AGP to identify or predict cows with low DMI. Plasma samples (n = 2,086) from 434 Holstein cows in 6 studies were analyzed on d -21, -13 ± 2, -3, 1, 3, 7 ± 1, 14 ± 1, and 21 ± 1 relative to parturition. A commercially available ELISA kit specific for bovine AGP was validated, and 2 internal controls were analyzed on each plate with interplate variation of 15.0 and 17.3%, respectively. Bivariate analysis was used to assess the relationship between AGP and DMI. For significant associations, treatment(study) was added to the model, and quadratic associations were included in the model if significant. Plasma AGP concentration (±SEM) increased from 213 ± 37.3 μg/mL on d -3 to 445 ± 60.0 μg/mL on d 14. On d 3, AGP was associated negatively with DMI in a quadratic manner for wk 1 and wk 2 and linearly for wk 3. Day 7 AGP was associated negatively with DMI in a quadratic manner for wk 2 and linearly for wk 3. Similarly, d 14 AGP was negatively associated with DMI for wk 3 and wk 4. As d 3 AGP concentration increased over the interquartile range, a calculated 1.4 (8.5%), 0.5 (2.7%), and 0.4 (1.9%) kg/d reduction in predicted DMI was detected during wk 1, 2, and 3, respectively. Using bivariate analysis, d 3 AGP explained 10% of the variation in DMI during wk 1. We explored the clinical utility of d 3 AGP to diagnose low DMI, defined as wk 1 DMI >1 standard deviation below the mean. Receiver operating characteristic analysis identified a threshold of 480.9 μg/mL, providing 76% specificity and 48% sensitivity (area under the curve = 0.60). Limited associations occurred between AGP and blood biomarkers; however, AGP was associated with plasma haptoglobin concentration postpartum and incidence of displaced abomasum, retained placenta, and metritis. These results demonstrate a negative association between plasma AGP concentration and DMI in early-postpartum dairy cows, although its diagnostic performance was marginal. Further investigation into whether AGP directly suppresses DMI in dairy cattle is warranted.

Effects of propionate concentration on short-term metabolism in liver explants from dairy cows in the postpartum period

Our objective was to determine the temporal effects of increasing supply of propionate on propionate metabolism in liver tissue of dairy cows in the postpartum (PP) period. A total of 6 dairy cows [primiparous: n = 3, 9.00 ± 1.00 d PP (mean ± SD) and multiparous: n = 3; 4.67 ± 1.15 d PP] were biopsied for liver explants in a block-design experiment. Explants were treated with 3 concentrations of [¹³C₃]sodium propionate of 1, 2, or 4 mM. Explants were incubated in 2 mL of Medium 199 supplemented with 1% BSA, 0.6 mM oleic acid, 2 mM sodium l-lactate, 0.2 mM sodium pyruvate, and 0.5 mMl-glutamine at 38°C and sampled at 0.5, 15, and 60 min. Increasing the concentration of [¹³C₃]propionate increased total ¹³C% enrichment of propionyl coenzyme A (CoA), succinate, fumarate, malate, and citrate with time. Concentration of propionate did not affect total ¹³C% enrichment of hepatic glucose or acetyl CoA, but total ¹³C% enrichment increased with time for hepatic glucose. The ¹³C labeling from propionate was incorporated into acetyl CoA, but increased concentrations of propionate did not result in greater labeling of acetyl CoA. However, increases in ¹³C% enrichment of [M+4]citrate and [M+5]citrate concentrations of [¹³C₃]propionate indicate propionate conversion to acetyl CoA and subsequent entry of acetyl CoA into the tricarboxylic acid cycle in dairy cows in the PP period. This research presents evidence that despite an increase in hepatic acetyl CoA concentration and general consensus on the upregulation of gluconeogenesis of dairy cows during the PP period, carbon derived from propionate contributes to the pool of acetyl CoA, which increases as concentration of propionate increases, in addition to stimulating oxidation of acetyl CoA from other sources. Because of the hypophagic effects of propionate, but importance of propionate as a glucose precursor, a balance of propionate supply to dairy cows could lead to improvements in dry matter intake, and subsequently, health and production in dairy cows.

Influence of forage level and corn grain processing on whole-body urea kinetics, and serosal-to-mucosal urea flux and expression of urea transporters and aquaporins in the ovine ruminal, duodenal, and cecal epithelia

The objectives were to determine the effects of forage level and grain processing on whole-body urea kinetics, N balance, serosal-to-mucosal urea flux (Jsm-urea), and messenger ribonucleic acid (mRNA) abundance of urea transporter-B (UT-B; SLC14a1) and aquaporins (AQP) in ovine ruminal, duodenal, and cecal epithelia. Thirty-two wether lambs were blocked by body weight into groups of four and assigned to one of four diets (n = 8) in a 2 × 2 factorial design. Dietary factors were forage level (30% [LF] vs. 70% [HF]) and corn grain processing (whole-shelled [WS] vs. steam-flaked [SF]). Four blocks of lambs (n = 4) were used to determine urea kinetics and N balance using 4-d [15N15N]-urea infusions with concurrent fecal and urine collections. Lambs were killed after 23 d of dietary adaptation. Ruminal, duodenal, and cecal epithelia were collected to determine Jsm-urea and mRNA abundance of UT-B and AQP. Lambs fed LF had greater intakes of dry matter (DMI; 1.20 vs. 0.86 kg/d) and N (NI; 20.1 vs. 15.0 g/d) than those fed HF (P < 0.01). Lambs fed SF had greater DMI (1.20 vs. 0.86 kg/d) and NI (20.6 vs. 14.5 g/d) than those fed WS (P < 0.01). As a percentage of NI, total N excretion was greater in lambs fed HF compared with those fed LF (103% vs. 63.0%; P < 0.01) and was also greater in lambs fed WS compared with those fed SF (93.6% vs. 72.1%; P = 0.02). Retained N (% of NI) was greater in lambs fed LF compared with those fed HF (37.0% vs. -2.55%; P < 0.01). Lambs fed SF had a greater (P = 0.02) retained N (% of NI; 28.0% vs. 6.50%) compared with those fed WS. Endogenous urea production (UER) tended (P = 0.09) to be greater in lambs fed HF compared with those fed LF. As a proportion of UER, lambs fed HF had a greater urinary urea-N loss (0.38 vs. 0.22) and lower urea-N transferred to the gastrointestinal tract (GIT; 0.62 vs. 0.78) or urea-N used for anabolism (as a proportion of urea-N transferred to the GIT; 0.12 vs. 0.26) compared with lambs fed LF (P < 0.01). Ruminal Jsm-urea was unaffected by diet. Duodenal Jsm-urea was greater (P < 0.01) in lambs fed HF compared with LF (77.5 vs. 57.2 nmol/[cm2 × h]). Lambs fed LF had greater (P = 0.03) mRNA expression of AQP3 in ruminal epithelia and tended (P = 0.06) to have greater mRNA expression of AQP3 in duodenal epithelia compared with lambs fed HF. Expression of UT-B mRNA was unaffected by diet. Our results showed that feeding more ruminally available energy improved N utilization, partly through a greater proportion of UER being transferred to the GIT and being used for anabolic purposes.

Effect of anti-inflammatory treatment on systemic inflammation, immune function, and endometrial health in postpartum dairy cows

Systemic inflammation (SI) is increasingly studied in several species because it may be central in many metabolic disturbances and be a risk factor for clinical disease. This proof-of-concept study evaluated the effects of the anti-inflammatory drug meloxicam on markers of SI and energy metabolism, polymorphonuclear neutrophil (PMN) function, and endometritis in clinically healthy postpartum dairy cows. Cows received meloxicam (0.5 mg/kg of body weight; n = 20) once daily for 4 days (10-13 days postpartum) or were untreated (n = 22). Blood samples were collected -7, 1, 3, 5, 7, 10, 11, 12, 13, 14, 18, 21, 28, and 35 days relative to calving to measure serum concentrations of metabolic and inflammatory markers. Function of peripheral blood PMN were evaluated at 5, 10, 14, and 21, and proportion of PMN in endometrial cytology were performed at 5, 10, 14, 21, 28 and 35 days postpartum. Meloxicam decreased serum haptoglobin from the second until the last day of treatment, and improved indicators of energy metabolism (lesser β-hydroxybutyrate and greater insulin-like growth factor-1 during treatment, and greater glucose at the end of treatment than control cows). This improved PMN function at 14 days postpartum, but the endometrial inflammatory status was not affected.

Short-term feed intake regulation of dairy cows fed a total mixed ration or grazing forage oats

The integration of feeding behaviour with hepatic and endocrine–metabolic signals provides insights for a better understanding of short-term intake in dairy pasture-based systems. Therefore, the objective was to quantify hepatic and endocrine–metabolic signals before and after the first daily feeding event relating to feeding behaviour in a total mixed ration (TMR) versus a grazing pasture-based diet. During 15 days of adaptation and 5 days of measurements, 14 multiparous Holstein cows (days in milk = 148 ± 12.7; liveweight = 535 ± 10.9 kg; body condition score = 2.8 ± 0.08 (1–5 scale); milk yield = 28.9 ± 3.32 kg) were assigned to two treatments in a randomised block design: PAS = pasture (herbage allowance = 45 kgDM/cow.day; dry matter (DM) = 21%, net energy requirements for maintenance and lactation = 6.7 MJ/kgDM) + concentrate (0.9% of liveweight) or TMR (55:45 forage:concentrate ratio, as-dry basis; DM = 40%, net energy requirements for maintenance and lactation = 7.2 MJ/kgDM) ad libitum in a free stall facility. The DM intake of the first feeding event, feeding behaviour, and total DM intake and milk production, were measured. Blood and liver samples were taken before and after the first feeding event for hormones and metabolites determination. Comparing TMR versus PAS cows, total DM and net energy requirements for maintenance and lactation intake, milk production, and energy balance were greater (P &lt; 0.05), eating and rumination activities were lower (9.2%, P &lt; 0.01; 2.4%, P = 0.06 respectively) and resting activity was greater (11.6%, P &lt; 0.01), whereas duration and DM intake of the first feeding event did not differ. The insulin:glucagon ratio and liver adenosine triphosphate:adenosine diphosphate ratio increased (P &lt; 0.05), and plasma glucose decreased (P &lt; 0.05) after the first feeding event only in TMR cows, probably due to greater flux of propionate to the liver. A negative correlation between post-feeding liver adenosine triphosphate:adenosine diphosphate ratio and post-feeding liver acetyl coenzyme A (r = –0.82, P = 0.045) was also observed only in TMR cows. It is concluded that hepatic and metabolic signals known to support the hepatic oxidation theory in TMR-fed cows appear not to affect the cessation of the first feeding event in mid-lactation cows grazing a pasture-based diet. Further research is required to relate intake rate, flux of nutrients to liver and its response in hepatic metabolism in grazing dairy cows.

The effect of uncouplers of oxidative phosphorylation on the feeding behavior of lactating dairy cows

Our objective was to determine the effects of uncouplers of oxidative phosphorylation on feeding behavior of lactating dairy cows. We hypothesized that uncouplers of oxidative phosphorylation would increase meal size and meal length and performed 2 experiments to test our hypothesis. In experiment 1, 4 late-lactation cows (345 ± 48.4 d in milk; mean ± SD) were administered a daily intrajugular injection of either 10 mg/kg of BW^0.75 of 2,4-dinitrophenol methyl ether (DNPME) and propylene carbonate or propylene carbonate (control; CON) in a crossover design with 2-d periods. In experiment 2, 8 early-lactation cows (11.3 ± 0.89 d in milk) were administered a daily intrajugular injection via jugular catheter of either 50 mg/kg of BW of sodium salicylate (SAL) and saline or saline (control; CON) in a crossover design with 1-d periods. Feeding behavior was recorded by a computerized data acquisition system and analyzed for the first 4 h after access to feed within 15 min of treatment for both experiments. Neither DNPME nor SAL affected meal size over the first 4 h after access to feed. However, DNPME increased meal length by 6.4 min (26.3 vs. 19.9 min) and tended to decrease the number of meals (2.55 vs. 2.78 meals/4 h) over the first 4 h after access to feed compared with CON. Both DNPME and SAL decreased eating rate over the first 4 h after access to feed compared with their respective controls (0.10 vs. 0.12 kg/min for DNPME vs. CON; 0.06 vs. 0.07 kg/min for SAL vs. CON). Lack of treatment effects on meal size may have been caused by increased rate of oxidation of fuels compensating for the disruption of oxidative phosphorylation.

Evaluation of some blood liver parameters in cows with subclinical and clinical ketosis

The purpose of the present study was to establish the changes in some blood liver parameters in cows in different physiological conditions with subclinical (SCK) and clinical ketosis (CK). The study was performed on 157 Holstein cows with annual milk yield of 9,000–11,000 L. The animals were divided into 3 groups: I group – pregnant cows (from day 15 to day 0 pre-calving); II group – recently calved (from day 0 to day 15 postpartum) and III group – lactating (from day 30 to 45 postpartum). Blood concentrations of β-hydroxybutyric acid (ВНВА) (mmol/L), glucose (mmol/L), total protein (g/L), albumin (g/L) and total bilirubin (μmol/L) were assayed in all cows. The animals were divided in groups with SCK and CK according to their blood BHBA levels. It was established, that the con-centrations of total bilirubin were statistically significantly elevated vs control groups, while blood glucose, total protein and albumin values decreased, reflecting the impaired liver function in cows with SCK and CK.

Feed restriction to induce and meloxicam to mitigate potential systemic inflammation in dairy cows before calving

Most dairy cows experience a transient decrease in feed intake in the 1 to 2 wk before calving, which has been associated with systemic inflammation (SI), indicated by increased blood haptoglobin (Hp) concentration. We aimed to characterize the association between prepartum decrease in feed intake and the onset of SI and, if present, the ability of meloxicam (MEL), a non-steroidal anti-inflammatory drug, to mitigate SI. Holstein cows (n = 45) were assigned to control (n = 13), feed restriction (FR) untreated (FR-U; n = 15), and FR treated with MEL (FR-T; n = 17) groups. Daily feed intake was measured from -22 d from expected parturition until 35 d postpartum. Control cows were fed ad libitum, whereas FR-U and FR-T cows were reduced to 60% of their average intake for 4 consecutive days (-15 to -12 d from expected calving). The FR-T cows received MEL (0.5 mg/kg of body weight) once daily for 4 consecutive days (-13 to -10 d from expected calving). Blood samples were collected -22, -15, -14, -13, -12, -10, -7, -5, -3, 0, 1, 3, 5, 7, 15, 22, and 35 d relative to calving to measure serum concentrations of total calcium, total protein, albumin, globulin, cholesterol, urea, glucose, gamma-glutamyl transferase, aspartate aminotransferase, glutamate dehydrogenase, β-hydroxybutyrate, nonesterified fatty acids, Hp, and insulin-like growth factor-1. Serum concentrations of lipopolysaccharide-binding protein were measured -22, -15, -14, -13, -12, and -10 d from expected calving. Simplified glucose tolerance tests were performed on -15, -12, -5, 1, and 5 d relative to calving. Mixed linear regression models were used to assess the effects of FR and MEL on each metabolite. The interaction between treatment group and blood sampling day was forced into each model. All models accounted for body condition score, parity, and the cow as a random effect. Nonesterified fatty acids concentrations in both the FR-U and FR-T groups significantly increased from the second until the last day of FR. Feed restriction increased urea concentrations compared with the control group on -14 d but decreased urea concentrations on -10 d from expected calving. Control cows had greater β-hydroxybutyrate concentrations compared with FR cows on 15, 21, and 35 d postpartum. For all other metabolites, no differences were found. This model of FR produced substantial fat mobilization but based on serum Hp and lipopolysaccharide-binding protein concentrations did not generate measurable SI; therefore, we were unable to evaluate the ability of MEL to mitigate SI.

Effects of timing of palmitic acid supplementation on production responses of early-lactation dairy cows

The objective of our study was to evaluate the effects of timing of palmitic acid (C16:0) supplementation on production responses of early-lactation dairy cows. Fifty-two multiparous cows were used in a randomized complete block design experiment. During the fresh period (FR; 1-24 d in milk) cows were assigned to either a control diet containing no supplemental fat (CON) or a diet supplemented with C16:0 (palmitic acid, PA; 1.5% of diet dry matter). During the peak (PK) period (25-67 d in milk) cows were assigned to either a CON diet or a PA (1.5% of diet dry matter) diet in a 2 × 2 factorial arrangement of treatments considering the diet that they received during the FR period. During the FR period, we did not observe treatment differences for dry matter intake or milk yield. Compared with CON, PA increased the yield of 3.5% fat-corrected milk by 5.30 kg/d, yield of energy-corrected milk (ECM) by 4.70 kg/d, milk fat content by 0.41% units, milk fat yield by 280 g/d, and protein yield by 100 g/d. The increase in milk fat associated with the PA treatment during the FR period occurred due to an increase in yield of 16-carbon milk fatty acids (FA) by 147 g/d (derived from both de novo synthesis and extraction from plasma) and preformed milk FA by 96 g/d. Compared with CON, PA decreased body weight (BW) by 21 kg and body condition score (BCS) by 0.09 units and tended to increase BW loss by 0.76 kg/d. Although PA consistently increased milk fat yield and ECM over time, a treatment × time interaction was observed for BW and BCS due to PA inducing a greater decrease in BW and BCS after the second week of treatments. Feeding PA during the PK period increased milk yield by 3.45 kg/d, yield of 3.5% fat-corrected milk by 4.50 kg/d, yield of ECM by 4.60 kg/d, milk fat content by 0.22% units, milk fat yield by 210 g/d, protein yield by 140 g/d, and lactose yield by 100 g/d but tended to reduce BW by 10 kg compared with CON. Also, during the PK period we observed an interaction between diet fed in the FR and PK periods for milk fat yield due to feeding PA during the PK period increasing milk fat yield to a greater extent in cows that received the CON diet (+240 g/d) rather than the PA diet (+180 g/d) during the FR period. This difference was associated with the yield of preformed FA because feeding PA during the PK period increased the yield of preformed milk FA only in cows that received the CON diet during the FR period. In conclusion, feeding a C16:0 supplement to early-lactation cows consistently increased the yield of ECM in both the FR and PK periods compared with a control diet. For some variables, the effect of feeding C16:0 was affected by timing of supplementation because milk yield increased only during the PK period and BW decreased to a greater extent in the FR period. Regardless of diet fed in the FR period, feeding a C16:0 supplement during the PK period increased yields of milk and milk components.

Occurrence of subclinical metabolic disorders in dairy cows from western Santa Catarina state, Brazil

ABSTRACT: The management of dairy herds during the transition period has been studied in several studies due to the severe adjustments to which cows are submitted in the metabolism of carbohydrates, lipids and minerals at early lactation. This is a period when occurs most of the metabolic disorders in dairy cows, especially in their subclinical form. Hitherto a lack of information exists on the occurrence of subclinical metabolic disorders in Brazil. The aim of this study was to determine the occurrence of subclinical metabolic disorders, including ketosis, liver lipidosis, hypocalcemia, lactacidemia and hypomagnesemia, as well as phosphorous, copper and zinc deficiency in dairy cattle from the western region of Santa Catarina state, southern Brazil, during the first 30 days of lactation. Blood samples from 15 dairy herds managed in intensive production (free-stall) and semi-confined systems were collected. Milk yield, reproduction and health data of the herd were recorded in a questionnaire, based on the records of the farm and on the observations during samples collection. Blood samples were collected for the measurement of beta-hydroxybutyrate (BHB) and lactate using portable monitors at the farm and for obtaining serum to perform the following biochemical determinations: total calcium, phosphorus, magnesium, albumin, aspartate transaminase (AST) and creatine kinase (CK) by UV-visible spectrophotometry, and copper and zinc by atomic absorption spectrophotometry. In this study, the cutoff points considered were as follows: serum BHB concentrations >1.2mmol/L for subclinical ketosis, AST >140U/L and CK <94U/L for subclinical liver lipidosis, serum lactate concentrations >2.2mmol/L for lactacidemia, serum total calcium concentrations <7.5mg/dL for subclinical hypocalcemia, serum magnesium concentration <1.7mg/dL for hypomagnesemia, serum phosphorus concentration <2.5mg/dL for phosphorus deficiency, serum copper concentrations <32.8μg/dL for copper deficiency, and serum zinc concentrations <60μg/dL for zinc deficiency. The results showed an occurrence of 9% for subclinical ketosis, 11% for subclinical liver lipidosis, 44.5% for lactacidemia, 11% for subclinical hypocalcemia, 7.4% for subclinical hypomagnesemia, 10.7% for copper deficiency and 8.7% for zinc deficiency. According to the survey results, the occurrence of subclinical ketosis, lipidosis and hypocalcemia in western Santa Catarina differ from data found in the literature

Responses of fresh cows to three feeding strategies that reduce starch levels by feeding beet pulp

The study objective was to evaluate the effects of reducing dietary starch content in fresh cow diets while maintaining NDF levels by substituting barley grain (BG), corn silage (CS), or both with beet pulp (BP) on nutrient digestion, ruminal fermentation, DMI, lactation performance, meal patterns, chewing activity, and sorting behavior. Thirty-six multiparous cows were randomly assigned to 1 of 4 experimental diets from calving to 21 d in lactation. Experimental diets were a high-starch diet with ground BG (CO; 24.9% starch; 0% BP) and 3 low-starch diets: the CO with BP substituted for ground BG (BB; 19.6% starch; 7% BP), the CO with BP substituted for CS (BC; 20.6% starch; 12% BP), or the CO with BP substituted for CS and ground BG (BCB; 20.3% starch; 12% BP). The CO, BB, BC, and BCB contained 33.4, 34.4, 32.9, and 33.7% NDF, respectively, and 23.1, 22.0, 18.2, and 19.2% forage NDF, respectively. There was no effect of diet on total tract nutrient digestibility ( > 0.20), ruminal pH ( = 0.49), or total VFA ( = 0.39). However, diets affected molar proportions of propionate and acetate ( ≤ 0.01). Relative to CO cows, the molar propionate percentage was less in BB cows ( < 0.01) and tended to be greater in BC cows ( = 0.10), whereas the molar percentage of acetate was less in BC cows than in BB ( < 0.01) and CO cows ( = 0.02). Relative to CO cows (16.50 kg/d), DMI was greater for BC (17.70 kg/d; < 0.01) and BCB cows (17.50 kg/d; = 0.01), but it was less in BB cows (15.60 kg/d; = 0.02). Similar to DMI results, milk yields tended to be greater for BC (37.89 kg/d; = 0.08) and BCB cows (37.81 kg/d; = 0.09) compared with CO cows (35.41 kg/d), but BB cows (33.05 kg/d) tended to produce less milk than CO cows ( = 0.1). Milk fat content tended to be less in BC ( = 0.08) and BCB cows ( = 0.10) than in CO cows. There was no effect of diet on eating and rumination patterns ( ≥ 0.18), except shortened meal intervals for BC and BCB cows compared with CO cows ( = 0.02). Dietary treatments did not affect chewing activities per day or bout ( = 0.50), but BC and BCB cows spent less time on chewing activities per kilogram DM ( < 0.01) and NDF intake ( < 0.01) compared with CO cows. Cows fed the BC and BCB sorted for long particles (>19 mm; < 0.01) but against particles < 1.18 mm ( < 0.01). In the present study, propionate did not seem to play a central role in feed intake regulation of fresh cows, because BB cows had depressed DMI and the lowest molar proportion of propionate. However, reducing starch levels in fresh cow diets by replacing CS and both CS and BG with BP positively affected DMI and milk yield.

Metabolic Disorders in the Transition Period Indicate that the Dairy Cows' Ability to Adapt is Overstressed

Simple Summary

Metabolic disorders are a key problem in the transition period of dairy cows and often appear before the onset of further health problems. Problems derive from difficulties animals have to adapt to large variations and disturbances occurring both outside and inside the organism. A lack of success in solving these issues may be due to predominant approaches in farm management and agricultural science, dealing with such disorders as merely negative side effects. Instead, a successful adaptation of animals to their living conditions should be seen as an important end in itself. Both farm management and agricultural sciences should support animals in their ability to cope with nutritional and metabolic challenges by employing a functional and result-driven approach.

Abstract

Metabolic disorders are a key problem in the transition period of dairy cows and often appear before the onset of further health problems. They mainly derive from difficulties the animals have in adapting to changes and disturbances occurring both outside and inside the organisms and due to varying gaps between nutrient supply and demand. Adaptation is a functional and target-oriented process involving the whole organism and thus cannot be narrowed down to single factors. Most problems which challenge the organisms can be solved in a number of different ways. To understand the mechanisms of adaptation, the interconnectedness of variables and the nutrient flow within a metabolic network need to be considered. Metabolic disorders indicate an overstressed ability to balance input, partitioning and output variables. Dairy cows will more easily succeed in adapting and in avoiding dysfunctional processes in the transition period when the gap between nutrient and energy demands and their supply is restricted. Dairy farms vary widely in relation to the living conditions of the animals. The complexity of nutritional and metabolic processes and their large variations on various scales contradict any attempts to predict the outcome of animals’ adaptation in a farm specific situation. Any attempts to reduce the prevalence of metabolic disorders and associated production diseases should rely on continuous and comprehensive monitoring with appropriate indicators on the farm level. Furthermore, low levels of disorders and diseases should be seen as a further significant goal which carries weight in addition to productivity goals. In the long run, low disease levels can only be expected when farmers realize that they can gain a competitive advantage over competitors with higher levels of disease.

Feed intake is related to changes in plasma nonesterified fatty acid concentration and hepatic acetyl CoA content following feeding in lactating dairy cows

The relationship between hepatic acetyl CoA (AcCoA) content and dry matter intake (DMI) was evaluated using 28 multiparous Holstein cows; 14 were early postpartum (PP; 12.6 ± 3.8 d in milk) and 14 were late-lactation cows (LL; 269 ± 30 d in milk). Cows were fed once daily, and DMI was determined for the first 4h after feeding. Liver and blood samples were collected before feeding and 4h after feeding. Feed intake over the 4-h period ranged from 3.7 to 9.6 kg of dry matter and was similar for the 2 stages of lactation. Before feeding, hepatic AcCoA content was greater for PP compared with LL cows (34.4 vs. 12.5 nmol/g), and decreased over the 4h after feeding for PP only (28.7 vs. 34.4 nmol/g). The range for change in AcCoA over the 4-h period was wide for both PP (-24.3 to 10.4 nmol/g) and LL (-5.7 to 16.1 nmol/g), and was related negatively to DMI at 4h for both PP (R(2) = 0.55) and LL (R(2) = 0.31). The reduction in plasma NEFA concentration over the 4-h period was greater for PP than LL cows (-681 vs. -47 µEq/L), and was related to DMI at 4h for both PP and LL (both R(2) = 0.38). Greater DMI among cows over the first 4h after feeding might have been from a sharper reduction in supply of AcCoA in the liver for oxidation during meals because of the reduction in plasma NEFA concentration. Consistent with this is that the change in AcCoA was positively related to the reduction in plasma NEFA concentration for PP cows (R(2) = 0.31). However, change in plasma NEFA concentration was not related to change in hepatic AcCoA in LL cows, indicating that the pool of AcCoA in LL cows is not as dependent on NEFA flux to the liver as that of PP cows. Further research is required to determine production and fate of AcCoA within the timeframe of meals and the effects of feeding on energy charge in hepatic tissue.