Dry cow diet, management, and energy balance as risk factors for displaced abomasum in high producing dairy herds

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.

Transition cow nutrition and management strategies of dairy herds in the northeastern United States: Part III-Associations of management and dietary factors with analytes, health, milk yield, and reproduction

The objective was to evaluate relationships between putative periparturient management and dietary factors at the pen and herd levels with metabolic- and inflammation-related analytes, health disorders, milk yield, and reproductive performance. Multiparous and primiparous cows from 72 farms in the northeastern United States were enrolled in a prospective cohort study. Farms were visited 3 times during the prepartum and postpartum periods: during the far-off dry, close-up dry, and fresh periods. Pen measurements were taken at each visit for the pens where cows sampled were housed, and particle size was determined for the total mixed ration for the pen. A survey was used to acquire data on herd-level management variables. Blood samples were collected from the same 11 to 24 cows per farm during the close-up and fresh period visits. Whole blood was analyzed for postpartum β-hydroxybutyrate (BHB) concentrations, and plasma was analyzed for prepartum and postpartum nonesterified fatty acids (NEFA) and postpartum haptoglobin (Hp) concentrations. Health event, milk yield, and reproductive records were acquired through the records management software program used on the farm. For the pen-level analysis, primiparous and multiparous cows were analyzed separately. For the pen- and herd-level analysis, a simple linear regression was conducted on all possible explanatory variables. Variables were included in the full multivariable general linear model if P < 0.20, and a manual backward stepwise elimination process ensued until all variables had P < 0.10. Our results indicate that pen- and herd-level management factors are associated with blood biomarkers, health, milk yield, and reproductive performance. For the prepartum period, our results support increasing the proportion of particles on the 19-mm sieve of the Penn State Particle Separator, optimizing bunk space, and not overfeeding metabolizable energy (ME), to decrease the prevalence of elevated postpartum NEFA, BHB, and Hp concentrations, decrease disorder incidence, maximize milk yield, and improve pregnancy risk to first service. For the fresh period, our results generally support optimizing bunk space, avoiding commingling, increasing feeding frequency, avoiding high physically effective undigested neutral detergent fiber (NDF) after 240 h of in vitro fermentation and high total fermentable carbohydrate diets while optimizing the inclusion of forage NDF, and ensuring adequate diet ME and metabolizable protein to reduce the prevalence of elevated postpartum NEFA, BHB, and Hp concentrations, minimize disorder incidence, maximize milk yield, and improve pregnancy risk to first service. At the herd level, our results generally support not vaccinating in the calving pen, minimizing the number of prepartum and postpartum pen moves, and avoiding long stays in the calving pen after parturition to reduce the prevalence of elevated biomarker concentrations, decrease disorder incidence, increase milk yield, and improve reproductive performance.

Milk Yield, Hematological and Electrolyte Parameters in Primiparous Dairy Cows After Laparotomic Omentopexy and One-Step Laparoscopic Abomasopexy Treatments of Left Displaced Abomasum

This study aimed to evaluate the effects of two different treatment options for the correction of left displaced abomasum (LDA) on milk yield, hematological, electrolyte parameters, lactate and cortisol concentrations in primiparous cows. Twenty four Holstein cows were randomly assigned into three groups: cows treated with one-step laparoscopic abomasopexy (LPS, n=8), cows treated by left paralumbar omentopexy (LPT, n=8) and healthy cows (CON, n=8), matched by parity and days in milk. Blood samples were collected before (D0) and after (D0’) surgery, and 1 (D1), 3 (D3), 10 (D3) and 30 (D30) days following surgery. LPS and LPT cows at D0 as well as LPT cows at 30 d following surgery had lower milk yield than CON cows (P<0.05), while the service period was higher in LPT than in CON (P<0.05). WBC was lower at D0 as well as Hb and Ht at D0 and D0’ in CON group than those of LPS and LPT (P<0.05). Hyponatremia, hypochloremia and hypokalemia at D0 and D0’ were observed in LPS and LPT. In addition, LPT cows had lower Na and Cl at D1 and D3 and lower K at D1 than CON (P<0.05). Impaired hydration in LPS and LPT cows was accompanied by higher concentrations of lactate at D0, D0’, D1 and D3 (P<0.01) and cortisol at D0 and D0’ (P<0.01) compared with CON group, while LPT had higher cortisol at D0’ than LPS (P<0.05). These results indicated that LPS has the potential to improve the convalescence period of LDA in primiparous cows.

Mastitis: What It Is, Current Diagnostics, and the Potential of Metabolomics to Identify New Predictive Biomarkers

Periparturient diseases continue to be the greatest challenge to both farmers and dairy cows. They are associated with a decrease in productivity, lower profitability, and a negative impact on cows’ health as well as public health. This review article discusses the pathophysiology and diagnostic opportunities of mastitis, the most common disease of dairy cows. To better understand the disease, we dive deep into the causative agents, traditional paradigms, and the use of new technologies for diagnosis, treatment, and prevention of mastitis. This paper takes a systems biology approach by highlighting the relationship of mastitis with other diseases and introduces the use of omics sciences, specifically metabolomics and its analytical techniques. Concluding, this review is backed up by multiple studies that show how earlier identification of mastitis through predictive biomarkers can benefit the dairy industry and improve the overall animal health.

Association between prepartum nonesterified fatty acid serum concentrations and postpartum diseases in dairy cows

The objective of the present study was to quantify the relationships between prepartum nonesterified fatty acid (NEFA) concentrations and the development of subsequent diseases or culling and to identify the optimal thresholds allowing identification of animals at high risk of developing postpartum diseases or being culled. A total of 1,299 Holstein cows from 50 commercial herds located around Saint-Hyacinthe (QC, Canada) were enrolled in this observational study. Blood samples were collected from enrolled cows between 1 and 14 d before calving for serum NEFA quantification. Data concerning postpartum diseases and culling were collected from computerized record systems. The association between prepartum NEFA concentrations and postpartum diseases and culling was quantified using generalized linear mixed models, accounting for parity, season, week of sampling, and herd. Optimal NEFA thresholds were evaluated with receiver operator characteristic curves analysis for all diseases and then confirmed with generalized linear mixed models, considering NEFA as a categorical variable (high or low). Prepartum serum NEFA concentrations were associated with diseases diagnosed during the first 30 d in milk (DIM) and culling within the first 50 DIM. The optimal NEFA threshold associated with diseases was ≥290 µmol/L for retained placenta, ≥300 µmol/L for metritis and abomasal displacement, and ≥280 µmol/L for clinical mastitis and hyperketonemia. The level associated with the occurrence of at least one of these diseases in the first 30 DIM was ≥280 µmol/L, but it was ≥260 µmol/L for culling in the first 50 DIM. No relationship was found between NEFA concentrations and reproductive tract diseases (purulent vaginal discharge or cytological endometritis) or subclinical intramammary infection. Despite the strong relationship between prepartum NEFA concentrations and many diseases, the NEFA optimal threshold accuracy found in our study was low. In conclusion, our results demonstrate a relationship between NEFA concentrations in the 14-d period before calving and the subsequent development of diseases and culling. Prepartum NEFA concentrations thresholds between ≥260 and 300 µmol/L appear to be a strategic choice. However, considering the low accuracy, their use at the cow level should be performed with caution.

Symposium review: The role of adipose tissue in transition dairy cows: Current knowledge and future opportunities

Adipose tissue (AT) is a central reservoir of energy stored in the form of lipids. In addition, AT has been recognized as an immunologically and endocrinologically active tissue of dairy cattle. The recent literature on AT biology of transition dairy cows has often focused on the possible negative effects that originate from excessive body fat. However, the highly efficient energy-storage capability of this tissue is also vital to the adaptability of dairy cattle to the change in nutrient availability, and to support lactation and reproduction. An excessive degree of mobilization of this tissue, however, is associated with high circulating fatty acid concentrations, and this may have direct and indirect negative effects on reproductive health, productivity, and disease risk. Furthermore, rapid lipolysis may be associated with postpartum inflammation. Research on the role of AT is complicated by the greater difficulty of accessing and measuring visceral AT compared with subcutaneous AT. The objective of this review is to provide a transition cow-centric summary of AT biology with a focus on reviewing methods of measuring AT mass as well as to describe the importance for production, health, and reproductive success.

Invited review: The influence of immune activation on transition cow health and performance-A critical evaluation of traditional dogmas

The progression from gestation into lactation represents the transition period, and it is accompanied by marked physiological, metabolic, and inflammatory adjustments. The entire lactation and a cow's opportunity to have an additional lactation are heavily dependent on how successfully she adapts during the periparturient period. Additionally, a disproportionate amount of health care and culling occurs early following parturition. Thus, lactation maladaptation has been a heavily researched area of dairy science for more than 50 yr. It was traditionally thought that excessive adipose tissue mobilization in large part dictated transition period success. Further, the magnitude of hypocalcemia has also been assumed to partly control whether a cow effectively navigates the first few months of lactation. The canon became that adipose tissue released nonesterified fatty acids (NEFA) and the resulting hepatic-derived ketones coupled with hypocalcemia lead to immune suppression, which is responsible for transition disorders (e.g., mastitis, metritis, retained placenta, poor fertility). In other words, the dogma evolved that these metabolites and hypocalcemia were causal to transition cow problems and that large efforts should be enlisted to prevent increased NEFA, hyperketonemia, and subclinical hypocalcemia. However, despite intensive academic and industry focus, the periparturient period remains a large hurdle to animal welfare, farm profitability, and dairy sustainability. Thus, it stands to reason that there are alternative explanations to periparturient failures. Recently, it has become firmly established that immune activation and the ipso facto inflammatory response are a normal component of transition cow biology. The origin of immune activation likely stems from the mammary gland, tissue trauma during parturition, and the gastrointestinal tract. If inflammation becomes pathological, it reduces feed intake and causes hypocalcemia. Our tenet is that immune system utilization of glucose and its induction of hypophagia are responsible for the extensive increase in NEFA and ketones, and this explains why they (and the severity of hypocalcemia) are correlated with poor health, production, and reproduction outcomes. In this review, we argue that changes in circulating NEFA, ketones, and calcium are simply reflective of either (1) normal homeorhetic adjustments that healthy, high-producing cows use to prioritize milk synthesis or (2) the consequence of immune activation and its sequelae.

Role of insulin, insulin sensitivity, and abomasal functions monitors in evaluation of the therapeutic regimen in ketotic dairy cattle using combination therapy with referring to milk yield rates

Background:

Ketosis is one of the most critical metabolic disorders that occur in dairy cows after parturition due to negative energy balance around calving.

Aim:

The study evaluated a specific therapeutic regimen of ketosis in Holstein dairy cattle by using the combination therapy including hormones, corticosteroids, propylene glycol, and vitamin B12 as well as the use of milk yield rates, insulin, insulin sensitivity, and abomasal functions monitors as diagnostic biomarkers for the recovery of ketotic cows either pre-therapy (0 days) or post-therapy (7 and 14 days).

Methods:

This study was conducted on ketotic cattle (n = 20) belonged to different dairy farms in Cairo and Giza governorates, Egypt. The diseased cows were undergoing clinical and biochemical investigations for the estimation of serum insulin. Quantitative Insulin Sensitivity Check Index (RQUICKI) and abomasal functions monitor mainly serum levels of gastrin, pepsinogen, and chloride.

Results:

The milk production rates, cost: benefit analysis ratio, and benefit of the dairy farm in ketotic animals were significantly increased post-treatment. An improvement of insulin sensitivity was stated as serum insulin, and RQUICKI were remarkably increased in post-therapeutic ketotic cows. Monitors of the abomasal function revealed abomasal functions improvement through the significant elevation of blood gastrin and a substantial reduction in serum pepsinogen due to treatment.

Conclusion:

The study revealed high efficacy of the applied therapeutic strategy regime. It led to a high recovery rate and a very low relapse rate for ketosis. An improvement in milk yield rates, insulin sensitivity, and abomasal function monitors was reported. Hypoinsulinaemia was still reported, however, serum insulin was improved.

One-carbon, carnitine, and glutathione metabolism-related biomarkers in peripartal Holstein cows are altered by prepartal body condition

We investigated how prepartal body condition score (BCS) alters key hepatic enzymes associated with 1-carbon, carnitine, and glutathione metabolism and the related biomarkers in liver tissue and plasma of periparturient dairy cows. Twenty-six multiparous Holstein dairy cows were retrospectively selected according to BCS at 4 wk prepartum and divided into high (HighBCS, BCS ≥ 3.50) and normal (NormBCS, BCS ≤ 3.25) BCS groups (n = 13 each). Blood plasma samples were obtained at -30, -10, 7, 15, and 30 d relative to calving. Liver tissue biopsies were performed at -15, 7, and 30 d relative to calving, and samples were used to assess protein abundance via Western blot assay. Cows in the HighBCS group lost ∼1 unit of BCS between -4 and 4 wk around calving, while NormBCS cows lost ∼0.5 unit in the same period. Prepartal dry matter intake (DMI, kg/d) did not differ between groups. Compared with NormBCS cows, HighBCS cows had higher postpartal DMI and milk yield (+5.34 kg/d). In addition, greater overall plasma concentrations of fatty acids and activity of the neutrophil-enriched enzyme myeloperoxidase were observed in HighBCS compared with NormBCS cows. Despite similar reactive oxygen metabolite concentrations in both groups at 30 d, HighBCS cows had lower overall concentrations of β-carotene and tocopherol, explaining the lower (BCS × Time) antioxidant capacity (ferric reducing ability of plasma). The HighBCS cows also had greater liver malondialdehyde concentrations and superoxide dismutase activity at 30 d. Overall, compared with NormBCS cows, HighBCS cows had lower hepatic protein abundance of the 1-carbon metabolism enzymes cystathionine-β-synthase, betaine-homocysteine methyltransferase, and methionine adenosyltransferase 1 A (MAT1A), as well as the glutathione metabolism-related enzymes glutathione S-transferase α 4 and glutathione peroxidase 3 (GPX3). A lower protein abundance of glutathione S-transferase mu 1 (GSTM1) at -15 and 7 d was also observed. Regardless of BCS, cows had increased abundance of GSTM1 and GPX3 between -15 and 7 d around calving. A marked decrease of gamma-butyrobetaine dioxygenase 1 from -10 to 7 d in HighBCS compared with NormBCS cows suggested a decrease in de novo carnitine synthesis that was partly explained by the lower abundance of MAT1A. Overall, data suggest biologic links between BCS before calving, milk yield, immune response, and hepatic reactions encompassing 1-carbon metabolism, carnitine, and antioxidant synthesis.

Potential hemo-biological identification markers to the left displaced abomasum in dairy cows

Background

Left displaced abomasum (LDA) occurs at high frequency in the early postpartum period and can affect production performance of dairy cows. Clinical diagnosis of LDA is usually done by abdominal auscultation and percussion. The purpose of this study was to explore the potential applicability of blood biomarkers for early warning and diagnosis of LDA in dairy cows.

Results

Twenty early postpartum healthy cows and thirty early postpartum LDA cows of similar parity were used. A receiver operating characteristic curve (ROC) method was used to analyze the sensitivity of hematological biomarkers to LDA including energy balance metabolic biomarkers, liver/kidney function biomarkers, and minerals. A cut-off point was defined for each of the selected hematological biomarkers deemed sensitive markers of LDA. Compared with healthy cows, body condition score (BCS), dry matter intake (DMI) and milk production were lower in LDA cows. Among energy metabolism markers, serum non-esterified fatty acid (NEFA), β-hydroxybutyric acid (BHBA), insulin (INS), and revised quantitative insulin sensitivity check index (RQUICKI) levels were lower while serum glucagon (GC) was greater in LDA cows. Among the liver/kidney function biomarkers, activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), lactate dehydrogenase (LDH), the ratio of AST/ALT and levels of total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), albumin (ALB), blood urea nitrogen (BUN), creatinine, and total protein (TP) were greater in LDA cows. Among minerals analyzed, serum Cl, Ca, and K were lower in LDA cows. After ROC analysis, it was determined that serum Ca, INS, RQUICKI, ALT, GGT, and creatinine are potential indicators for early warning and diagnosis of LDA for early postpartum dairy cows.

Conclusions

Dairy cows with LDA were under severe negative energy balance (NEB), had signs of liver damage and potentially lower insulin sensitivity. A combination of multi-hematological biomarkers including Ca, INS, RQUICKI, ALT, GGT and creatinine has the potential to help identify cows at risk of LDA in the early postpartum period.

Cluster analysis to evaluate disease risk in periparturient dairy cattle

Predicting periparturient disease risk is of immense value to the dairy industry. Periparturient diseases are interrelated with each other; however, predicting the onset risk of these diseases has predominantly been based on a single blood parameter for a single disease. This study examined a new diagnostic method to predict the risk of periparturient diseases. We conducted cluster analysis of multiple blood constituents from 20 Holstein cattle at 1 week post-partum, and the cattle were divided into two groups, A or B. We then compared the periparturient and early-lactation blood constituents of these groups. Group B had significantly higher 3-hydroxybutyric acid concentrations and were suspected to have subclinical ketosis. Group B also had significantly lower calcium concentrations, with a tendency for subclinical hypocalcemia. We also performed discriminant analysis using blood parameters at 1 week post-partum, which grouped the population into the same two groups as the cluster analysis based on three variables: inorganic phosphorus, calcium, and either phospholipids or total cholesterol. We further showed that these discriminant functions could be used to predict the risk of periparturient disease even before parturition. Our results indicate that cluster analysis with multiple blood constituents is useful for predicting periparturient disease risks.

A Tale of Two Biomarkers: Untargeted 1H NMR Metabolomic Fingerprinting of BHBA and NEFA in Early Lactation Dairy Cows

Disorders of energy metabolism, which can result from a failure to adapt to the period of negative energy balance immediately after calving, have significant negative effects on the health, welfare and profitability of dairy cows. The most common biomarkers of energy balance in dairy cows are β-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA). While elevated concentrations of these biomarkers are associated with similar negative health and production outcomes, the phenotypic and genetic correlations between them are weak. In this study, we used an untargeted ¹H NMR metabolomics approach to investigate the serum metabolomic fingerprints of BHBA and NEFA. Serum samples were collected from 298 cows in early lactation (calibration dataset N = 248, validation N = 50). Metabolomic fingerprinting was done by regressing ¹H NMR spectra against BHBA and NEFA concentrations (determined using colorimetric assays) using orthogonal partial least squares regression. Prediction accuracies were high for BHBA models, and moderately high for NEFA models (R² of external validation of 0.88 and 0.75, respectively). We identified 16 metabolites that were significantly (variable importance of projection score > 1) correlated with the concentration of one or both biomarkers. These metabolites were primarily intermediates of energy, phospholipid, and/or methyl donor metabolism. Of the significant metabolites identified; (1) two (acetate and creatine) were positively correlated with BHBA but negatively correlated with NEFA, (2) nine had similar associations with both BHBA and NEFA, (3) two were correlated with only BHBA concentration, and (4) three were only correlated with NEFA concentration. Overall, our results suggest that BHBA and NEFA are indicative of similar metabolic states in clinically healthy animals, but that several significant metabolic differences exist that help to explain the weak correlations between them. We also identified several metabolites that may be useful intermediate phenotypes in genomic selection for improved metabolic health.

Bacterial Endotoxins and Their Role in Periparturient Diseases of Dairy Cows: Mucosal Vaccine Perspectives

During the periparturient period there is a significant increase in the incidence of multiple metabolic and infectious diseases in dairy cows. Dairy cows are fed high-grain diets immediately after calving to support production of large amounts of milk. Mounting evidence indicates these types of diets are associated with the release of high amounts of endotoxins in the rumen fluid. If infected, the udder and uterus additionally become important sources of endotoxins during the postpartum period. There is increasing evidence that endotoxins translocate from rumen, uterus, or udder into the systemic circulation and trigger chronic low-grade inflammatory conditions associated with multiple diseases including fatty liver, mastitis, retained placenta, metritis, laminitis, displaced abomasum, milk fever, and downer cow syndrome. Interestingly, endotoxin-related diseases are triggered by a bacterial component and not by a specific bacterium. This makes prevention of these type of diseases different from classical infectious diseases. Prevention of translocation of endotoxins into the host systemic circulation needs to take priority and this could be achieved with a new approach: mucosal vaccination. In this review article, we discuss all the aforementioned issues in detail and also report some of our trials with regards to mucosal vaccination of periparturient dairy cows.

Diagnostic performance of ultrasonography in clinical management of dairy cattle identified with left-sided ping sounds

Objectives:

Left displaced abomasum (LDA) is a common postparturient condition of high yielding dairy cattle. The diagnosis of LDA is challenging and has historically been based on findings that are not specific to the condition. The objective of the current study was to investigate the diagnostic performance of ultrasonography (USG) in the clinical management of dairy cows identified with left-sided ping sound postpartum.

Materials and methods:

Cows with reduced appetite postpartum and had audible left-sided ping sounds on abdominal auscultation were eligible to be prospectively recruited onto the study. The results of clinical findings and abdominal USG were recorded along with milk β-hydroxybutyrate levels, pH levels of abomaso/rumenocentesis samples, and findings on exploratory laparotomy. The diagnostic performance of USG and other clinical investigations was assessed by calculating the test sensitivity and specificity using exploratory laparotomy as a gold standard test.

Results:

A definitive diagnosis of LDA was made in 23 cows, 8 cows were diagnosed with peritonitis, and 4 cows with frothy tympany. The USG findings that were consistent with LDA were present in all cattle diagnosed with LDA at exploratory laparotomy. The USG findings over the past three intercostal space characteristics of LDA, however, were also present in five cases subsequently diagnosed with peritonitis and in all cases diagnosed with frothy tympany on exploratory laparotomy. The pH of abdomaso/rumenocentesis samples yielded the highest diagnostic accuracy (97.14%) as a single test in the current study.

Conclusions:

USG over the left abdominal wall despite being a highly sensitive test for the diagnosis of LDA has limitations as a diagnostic tool due to suboptimal specificity.

Improving nutritional accuracy and economics through a multiple ration-grouping strategy

The objective of this study was to develop a model application to systematize nutritional grouping (NG) management in commercial dairy farms. The model has 4 sub-sections: (1) real-time data stream integration, (2) calculation of nutritional parameters, (3) grouping algorithm, and (4) output reports. A simulation study on a commercial Wisconsin dairy farm was used to evaluate our NG model. On this dairy farm, lactating cows (n = 2,374 ± 185) are regrouped weekly in 14 pens according to their parity and lactation stage, for which 9 diets are provided. Diets are seldom reformulated and nutritional requirements are not factored to allocate cows to pens. The same 14 pens were used to simulate the implementation of NG using our model, closely following the current farm criteria but also including predicted nutritional requirements (net energy for lactation and metabolizable protein; NE_L and MP) and milk yield in an attempt to generate more homogeneous groups of cows for improved diet accuracy. The goal of the simulation study was to implement a continuous weekly system for cows' pen allocation and diet formulation. The predicted MP and NE_L requirements from the NG were used to formulate the diets using commercial diet formulation software and the same feed ingredients, feed prices, and other criteria as the current farm diets. Diet MP and NE_L densities were adjusted to the nutritional group requirements. Results from the simulation study indicated that the NG model facilitates the implementation of an NG strategy and improves diet accuracy. The theoretical diet cost and predicted nitrogen supply with NG decreased for low-nutritional-requirement groups and increased for high-nutritional-requirement groups compared with current farm groups. The overall average N supply in diets for NG management was 15.14 g/cow per day less than the current farm grouping management. The average diet cost was $3,250/cow per year for current farm management and $3,219/cow per year for NG, which resulted in a theoretical $31/cow per year diet cost savings.

Identification of disordered metabolic networks in postpartum dairy cows with left displacement of the abomasum through integrated metabolomics and pathway analyses

High-producing dairy cows are easily affected by left displacement of the abomasum (LDA) within 4 weeks postpartum. Although LDA is highly associated with metabolic disturbances, the related information on comprehensive metabolic changes, with the exception of some blood biochemical parameters, remains limited. In this study, the changes in plasma metabolites and in the metabolic profile of postpartum dairy cows with LDA were investigated through liquid chromatography coupled with quadrupole time of flight mass spectrometry (LC-Q/TOF-MS)-based metabolomics, and the metabolic networks related to LDA were constructed through metabolomics pathway analysis (MetPA). An obvious change in the metabolic profile was reflected by significant variations in 68 plasma metabolites in postpartum dairy cows with LDA, and these variations consequently altered 13 metabolic pathways (histidine metabolism, tyrosine metabolism, valine, leucine and isoleucine biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, arginine and proline metabolism, tryptophan metabolism, synthesis and degradation of ketone bodies, linoleic acid metabolism, arachidonic acid metabolism, citrate cycle, butanoate metabolism, vitamin B₆ metabolism and pyrimidine metabolism). This study shows that the more detailed information obtained by LC-Q/TOF-MS-based metabolomics and MetPA might contribute to a better understanding of the disordered metabolic networks in postpartum dairy cows with LDA.

Effects of feeding management on disease incidence and blood metabolites in dairy herds in Iwate Prefecture, Japan

The objective of the present study was to identify the effect of feeding management on disease incidence and blood metabolite levels in dairy herds in Iwate Prefecture, Japan. A generalized linear model approach was used to identify the risk factors for ketosis and displaced abomasum (DA) in dairy herds (n=30), and metabolic profile test (MPT) results were compared to verify the involvement of the factors. Consequently, the proportion of corn silage (CS) with ≥30% of dry matter (DM) fed to cows during the lactation period was confirmed as the most reliable risk factor for ketosis, while no risk factor was identified for DA. Meanwhile, the incidence rates of ketosis and DA were significantly (P<0.05) higher in the herds that were fed CS (n=20) than in those fed a non-CS diet (n=10). When the MPT results of the herds fed with CS containing ≥30% of DM (HCS group, n=4; 76 cows), with CS containing <30% of DM (LCS group, n=14; 285 cows), and a non-CS diet (NCS group, n=12; 236 cows) were compared, the HCS group showed higher beta-hydroxybutyric and lower blood urea nitrogen concentrations for until 49 days after parturition. Overall, feeding cows with CS diets containing over 30% of DM might increase their risk of developing negative energy and protein balances, thereby resulting in increasing incidences of ketosis in the Iwate Prefecture.

Cohort-level disease prediction by extrapolation of individual-level predictions in transition dairy cattle

Dairy cattle experience metabolic stress during the transition from late gestation to early lactation resulting in higher risk for several economically important diseases (e.g. mastitis, metritis, and ketosis). Metabolic stress is described as a physiological state composed of 3 processes: nutrient metabolism, oxidative stress, and inflammation. Current strategies for monitoring transition cow nutrient metabolism include assessment of plasma non-esterified fatty acids and beta-hydroxybutyrate concentrations around the time of calving. Although this method is effective at identifying cows with higher disease risk, there is often not enough time to implement intervention strategies to prevent health disorders from occurring around the time of calving. Previously, we published predictive models for early lactation diseases at the individual cow level at dry-off. However, it is unknown if predictive probabilities from individual-level models can be aggregated to the cohort level to predict cohort-level incidence. Therefore, our objective was to test different data aggregation methods using previously published models that represented the 3 components of metabolic stress (nutrient metabolism, oxidative stress, and inflammation). We included 277 cows from five Michigan dairy herds for this prospective cohort study. On each farm, two to four calving cohorts were formed, totaling 18 cohorts. We measured biomarker data at dry-off and followed the cows until 30 days post-parturition for cohort disease incidence, which was defined as the number of cows: 1) having one or more clinical transition disease outcome, and/or 2) having an adverse health event (abortion or death of calf or cow) within each cohort. We tested three different aggregation methods that we refer to as the p-central, p-dispersion, and p-count methods. For the p-central method, we calculated the averaged predicted probability within each cohort. For the p-dispersion method, we calculated the standard deviation of the predicted probabilities within a cohort. For the p-count method, we counted the number of cows above a specified threshold of predicted probability within each cohort. We built four sets of models: one for each aggregation method and one that included all three aggregation methods (p-combined method). We found that the p-dispersion method was the only method that produced viable predictive models. However, these models tended to overestimate incidence in cohorts with low observed counts and underestimate risk in cohorts with high observed counts.

Predictive models for early lactation diseases in transition dairy cattle at dry-off

During the transition period, dairy cattle undergo tremendous metabolic and physiological changes to prepare for milk synthesis and secretion. Failure to sufficiently regulate these changes may lead to metabolic stress, which increases risk of transition diseases. Metabolic stress is defined as a physiological state consisting of 3 components: aberrant nutrient metabolism, oxidative stress, and inflammation. Current monitoring methods to detect cows experiencing metabolic stress involve measuring biomarkers for nutrient metabolism. However, these biomarkers, including non-esterified fatty acids, beta-hydroxybutyrate, and calcium are typically measured a few weeks before to a few days after calving. This is a retroactive approach, because there is little time to integrate interventions that remediate metabolic stress in the current cohort. Our objective was to determine if biomarkers of metabolic stress measured at dry-off are predictive of transition disease risk. We designed a prospective cohort study carried out on 5 Michigan dairy farms (N = 277 cows). We followed cows from dry-off to 30 days post-calving. Diseases and adverse outcomes were grouped in an aggregate outcome that included mastitis, metritis, retained placenta, ketosis, lameness, pneumonia, milk fever, displaced abomasum, abortion, and death of the calf or the cow. We used best subsets selection to select candidate models for four different sets of models: one set for each component of metabolic stress (nutrient metabolism, oxidative stress, and inflammation), and a combined model that included all 3 components. We used model averaging to obtain averaged predicted probabilities across each model set. We hypothesized that the averaged predictions from the combined model set with all 3 components of metabolic stress would be more effective at predicting disease than each individual component model set. The area under the curve estimated using receiver operator characteristic curves for the combined model set (0.93; 95% confidence interval [CI] = 0.90-0.96) was significantly higher compared with averaged predictions from the inflammation (0.87; 95% CI = 0.83-0.91), oxidative stress (0.78; 95% CI = 0.72-0.84), and nutrient metabolism (0.73; 95% CI = 0.67-0.79) model sets (p < 0.05). Our results indicate that it may be possible to detect cattle at risk for some transition diseases as early as dry-off. This has important implications for disease prevention, as earlier identification of cows at risk of health disorders will allow for earlier implementation of intervention strategies. A limitation of the current study is that we did not perform external validation. Future validation studies are needed to confirm our findings.

Smart Animal Agriculture: Application of Real-Time Sensors to Improve Animal Well-Being and Production

Consumption of animal products such as meat, milk, and eggs in first-world countries has leveled off, but it is rising precipitously in developing countries. Agriculture will have to increase its output to meet demand, opening the door to increased automation and technological innovation; intensified, sustainable farming; and precision livestock farming (PLF) applications. Early indicators of medical problems, which use sensors to alert cattle farmers early concerning individual animals that need special care, are proliferating. Wearable technologies dominate the market. In less-value-per-animal systems like sheep, goat, pig, poultry, and fish, one sensor, like a camera or robot per herd/flock/school, rather than one sensor per animal, will become common. PLF sensors generate huge amounts of data, and many actors benefit from PLF data. No standards currently exist for sharing sensor-generated data, limiting the use of commercial sensors. Technologies providing accurate data can enhance a well-managed farm. Development of methods to turn the data into actionable solutions is critical.

Association between left-displaced abomasum corrected with 2-step laparoscopic abomasopexy and milk production in a commercial dairy farm in Italy

Background

Left displacement of the abomasum (LDA) is a condition of dairy cows that causes huge economic losses. The aim of the study was to evaluate the effect of LDA after on-farm correction by the 2-step laparoscopic abomasopexy on milk production based on 305-d milk yield on a commercial dairy farm in Italy.The study was performed between January 2011 and January 2014 on 58 Holstein Friesian cattle with left displacement of the abomasum in a commercial dairy farm in the farmland of Ozieri, Sardinia (Italy). Each cow underwent a 2-step laparoscopic abomasopexy performed by the same veterinarian. Each case was matched with a control herdmate by age, parity and calving date. Cows with LDA and healthy control cows also had a similar 305-d milk yield in the previous lactation. Data on milk production were collected using a dairy herd management software programme (Afimilk®, Afimilk Ltd., Israel). The 305-d lactation yield was obtained from the sum of daily milk yields for each cow. An unpaired Student’s t-test was used to compare changes in milk production, mean fat and protein percentage of cases and controls before and after surgical procedure.

Results

Data from 4 cows were excluded from the analysis due to post-surgical complications. 54 cases and 54 control cows participated in the study. We found that milk production significantly decreased from a baseline of 12,295 ± 1690 kg to 11,165 ± 1989 kg in the affected lactation. Conversely, a significant increase was observed for mean fat and protein percentage during lactation in case cows.

Conclusions

In the present study cows with left displacement of the abomasum corrected with 2-step laparoscopic abomasopexy produced less milk than their control herdmates. Each case and control pair in the present study came from the same farm in order to eliminate farm to farm differences in management, housing, season, etc. However, this limits the validity of our data to the specific situation described here.

A 100-Year Review: Metabolic modifiers in dairy cattle nutrition

The first issue of the Journal of Dairy Science in 1917 opened with the text of the speech by Raymond A. Pearson, president of the Iowa State College of Agriculture, at the dedication of the new dairy building at the University of Nebraska (J. Dairy Sci. 1:4-18, 1917). Fittingly, this was the birth of a new research facility and more importantly, the beginning of a new journal devoted to the sciences of milk production and manufacture of products from milk. Metabolic modifiers of dairy cow metabolism enhance, change, or interfere with normal metabolic processes in the ruminant digestive tract or alter postabsorption partitioning of nutrients among body tissues. Papers on metabolic modifiers became more frequent in the journal around 1950. Dairy farming changed radically between 1955 and 1965. Changes in housing and feeding moved more cows outside, and cows and heifers in all stages of lactation, including the dry period, were fed as a single group. Rations became wetter with the shift to corn silage as the major forage in many rations. Liberal grain feeding met the requirements of high-producing cows and increased production per cow but introduced new challenges; for example, managing and feeding cows as a group. These changes led to the introduction of new strategies that identified and expanded the use of metabolic modifiers. Research was directed at characterizing the new problems for the dairy cow created by group feeding. Metabolic modifiers went beyond feeding the cow and included environmental and housing factors and additives to reduce the incidence and severity of many new conditions and pathologies. New collaborations began among dairy cattle specialties that broadened our understanding of the workings of the cow. The Journal of Dairy Science then and now plays an enormously important role in dissemination of the findings of dairy scientists worldwide that address existing and new technologies.

Absorption of bicarbonate in sheep omasum

Transport of bicarbonate across the isolated epithelium of sheep omasum was studied in vitro in Ussing chambers in combination with the pH-Stat method. The transport of HCO₃^- occurred in both directions, but J_ms HCO₃^- was significant larger than J_sm. Reducing the activity of the apical Na/H exchanger by a low mucosal Na concentration caused a significant reduction of J_ms HCO₃^-. Mucosal amiloride or short chain fatty acids (25 mmol l^-1 SCFA) numerically decreased J_ms HCO₃^-, but their combination (amiloride + SCFA) caused a significant reduction, which was also observed after addition of the carboanhydrase inhibitor ethoxyzolamide. Concentrations of 5 or 15 mmol·l^-1 mucosal ammonia did not change transport rates. The obtained results indicate the importance of an undisturbed cytosolic pH for transcellular HCO₃^- transport, which is probably mediated by an anion exchanger in both the apical and basolateral membranes. Possible impairment of HCO₃^- transport appears to be an overlooked factor in the pathogenesis of displacement of the abomasum.

Indikatoren für Risiken bei Kühen in der Transitphase – eine Übersicht zu metabolischen Profilen

Erkrankungen von Milchkühen im peripartalen Zeitraum gelten als entscheidende Faktoren für eine Beeinträchtigung der Milchleistung und sind mittlerweile ein zentraler Aspekt der Herdendiagnostik. In den letzten 40 Jahren wurden anhand von Blutproben erstellte metabolische Profile zur Herdendiagnostik genutzt, wobei die Erfahrungen bezüglich der diagnostischen Wertigkeit differierten. Die Forschung führte zu umfangreichen Erkenntnissen darüber, wie physiologische Mechanismen bei der Kuh, das Management, die Umwelt sowie Interaktionen zwischen diesen Faktoren zur Entwicklung von Erkrankungen im peripartalen Zeitraum beitragen. Kühe mit hohem Risiko für eine erforderlich werdende Behandlung lassen sich anhand einer erhöhten Konzentration an β-Hydroxybutyrat (BHB) (> 1,2 mmol/l) in den ersten 7–10 Tagen nach dem Kalben identifizieren. Ergeben Herdenkontrollen bei 15–20% der Frischabkalber in der ersten Woche post partum erhöhte BHB-Konzentrationen, weist dies auf ein beträchtliches Krankheitsrisiko und Produktionsverluste hin. Auch eine erhöhte Serumkonzentration freier Fettsäuren (FFS) ist Hinweis für ein gesteigertes Krankheitsrisiko. In dieser Übersicht werden gesicherte (BHB, FFS) und weitere potenzielle Parameter erläutert, die sich, bei Untersuchung von Einzel- oder Poolproben, dazu eignen, das Risiko für Erkrankungen und den Ernährungszustand der Tiere einzuschätzen. Ihre Anwendung in Form metabolischer Profile zur Herdendiagnostik bei bestehenden Risiken oder im Rahmen der Herdenüberwachung wird dargestellt. Eine Poolprobe nach dem modifizierten „Compton Metabolic Profile“ ermöglicht die wirtschaftlichere Nutzung mehrerer Parameter, wenngleich diese Vorgehensweise die Interpreta - tion und die Anwendung in Abhängigkeit von der Herdengröße einschränken kann. Poolproben von fünf bis zehn Individuen repräsentieren genau das arithmetische Mittel aus den Werten der einzelnen Tiere. Von größter Bedeutung ist, dass die metabolischen Profile im Zusammenhang mit anderen diagnostischen Kennzahlen von Tier- und Betriebsanalysen, der Körperkonditionsbeurteilung und der Rationskontrolle genutzt werden. Nur so lässt sich ihr Wert im Rahmen der Herdenunter - suchung voll ausschöpfen.

Herd-Level Monitoring and Prevention of Displaced Abomasum in Dairy Cattle

Displaced abomasum (DA) is a postpartum disease that causes significant economic losses in the dairy industry. Abomasal atony and excessive production of gas have been reported as prerequisites for the development of DA. The exact cause of DA is unknown, yet infectious and metabolic disease, diet composition and physical form, cow comfort, and management of dairy cows during the transition period have been associated with the occurrence of this disorder. This review article discusses different factors that lead to the development of DA and strategies for monitoring DA and its comorbidities at the herd level.

Judicious use of prophylactic antimicrobials to reduce abdominal surgical site infections in periparturient cows: part 1 - a risk factor review

Surgical site infections (SSI) are an uncommon, but significant, consequence of surgical interventions. There are very few studies investigating SSI risk in veterinary medicine, and even fewer in cattle, despite the fact that major surgeries are commonly conducted on livestock. Furthermore, the suboptimal conditions under which such surgeries are frequently performed on livestock could be considered an important risk factor for the development of SSIs. With increasing public concern over the contribution of veterinary-prescribed antimicrobials to the emergence of antimicrobial-resistant bacteria in people, there is widespread scrutiny and criticism of antimicrobial use in livestock production medicine systems. While the causal link between antimicrobial resistance in livestock and people is heavily debated, it is clear that the prevalence of antimicrobial resistance, in any population, is closely correlated with the antimicrobial 'consumption' within that population. As the veterinary profession explores ways of addressing the emergence and selection of antimicrobial-resistant bacteria in food-producing animals, there is a need for veterinarians and producers to carefully consider all areas of antimicrobial use, and employ an evidence-based approach in designing appropriate clinical protocols. This paper aims to review current knowledge regarding the risk factors related to abdominal SSI in periparturient cows, and to encourage practitioners to judiciously evaluate both their standard operating procedures and their use of antimicrobials in these situations. In a second paper, to be published in a subsequent issue of Veterinary Record, these principles will be used to provide specific evidence-based recommendations for antimicrobial use in bovine abdominal surgery.

Concentrate supplementation of a diet based on medium-quality grass silage for 4 weeks prepartum: Effects on cow performance, health, metabolic status, and immune function

Because negative energy balance (EB) contributes to transition-period immune dysfunction in dairy cows, dietary management strategies should aim to minimize negative EB during this time. Prepartum diets that oversupply energy may exacerbate negative EB in early lactation, with detrimental effects on immune function. However, with lower body condition score (BCS) cows, it has been shown that offering concentrates in addition to a grass silage-based diet when confined during an 8-wk dry period resulted in increased neutrophil function in early lactation. The aim of this study was to examine if similar benefits occur when concentrate feeding was restricted to a 4-wk period prepartum. Twenty-six multiparous and 22 primiparous Holstein-Friesian cows were offered ad libitum access to medium-quality grass silage until 28 d before their predicted calving dates (actual mean of 32 d prepartum; standard deviation = 6.4). At this time multiparous cows had a mean BCS of 2.9 (standard deviation = 0.12) and primiparous cows a mean BCS of 3.0 (standard deviation = 0.14) on a 1 to 5 scale. Cows were then allocated in a balanced manner to 1 of 2 treatments (13 multiparous cows and 11 primiparous cows on each treatment): silage only (SO) or silage plus concentrates (S+C) until calving. Cows on SO were offered the same grass silage ad libitum. Cows on S+C were offered an ad libitum mixed ration of the same grass silage and additional concentrates in a 60:40 dry matter (DM) ratio, which provided a mean concentrate DM intake (DMI) of 4.5 kg/cow per d. After calving, all cows were offered a common mixed ration (grass silage and concentrates, 40:60 DM ratio) for 70 d postpartum. Offering concentrates in addition to grass silage during the 4 wk prepartum increased prepartum DMI (12.0 versus 10.1 kg/cow per d), EB (+40.0 versus +10.6 MJ/cow per d), and body weight (BW; 640 versus 628 kg), and tended to increase BCS (3.02 versus 2.97). However, postpartum DMI, milk yield, milk composition, BW change, BCS change, serum nonesterified fatty acid, and β-hydroxybutryrate concentrations, health, and corpus luteum measures were unaffected by treatment. The in vitro assays of neutrophil phagocytosis, neutrophil oxidative burst, and interferon gamma production, conducted on blood samples obtained at d 14 prepartum and d 3, 7, 14, and 21 postpartum, were unaffected by treatment. Primiparous cows had higher phagocytic fluorescence intensity at d 14 prepartum and d 3 and 7 postpartum; a higher percentage of neutrophils undergoing oxidative burst at d 3, 7, and 21 postpartum; and a higher oxidative burst fluorescence intensity at d 14 prepartum and d 7, 14, and 21 postpartum compared with multiparous cows. This suggests that neutrophil function of primiparous cows was less sensitive to the changes occurring during the transition period than that of multiparous cows. In conclusion, offering concentrates during the 4-wk period prepartum had no effect on postpartum DMI, milk yield, body tissue mobilization, EB, measures of neutrophil or lymphocyte function, health, or corpus luteum activity.

Lactational challenges in transition dairy cows

Lactation evolved to be the core functional system of providing maternal care in mammalian species. The mammary gland provides an ideally composed nutrient source for the newborn. In addition, colostrum provides passive immunisation after birth, and each suckling process supports the establishment and maintenance of a close mother–offspring bonding. The importance of lactation for the survival of the offspring is represented by a high metabolic priority of the mammary gland within the organism of the lactating animal. Therefore, animal breeding for high milk production has been quite successful, and modern breeding methods have allowed an enormous increase in the performance within only few generations of cows. Mainly in early lactation, most of the available nutrients are directed to the mammary gland, both those from feed, and those mobilised from body tissue. Therefore, milk production can be maintained at a high level despite a negative energy balance. However, the high metabolic load and mobilisation of body tissue requires adequate endocrine and metabolic regulation, which can be successful or less successful in individual animals, i.e. the dairy cow population consists of both metabolically robust and metabolically vulnerable dairy cows. While robust animals adapt adequately, vulnerable cows show often high plasma concentrations of non-esterified fatty acids and β-hydroxybutyrate, and are prone to various production-related diseases. In pasture- or forage-based feeding systems, an additional challenge is a limited availability of nutrients for milk production. Forage feeding without complementary concentrate leads to enormous metabolic disorders in high-yielding cows, but is tolerated in dairy cows with a moderate genetic-performance level.

Increased serum serotonin improves parturient calcium homeostasis in dairy cows

Hypocalcemia in dairy cows is caused by the sudden increase in calcium demand by the mammary gland for milk production at the onset of lactation. Serotonin (5-HT) is a key factor for calcium homeostasis, modulating calcium concentration in blood. Therefore, it is hypothesized that administration of 5-hydroxy-l-tryptophan (5-HTP), a 5-HT precursor, can increase 5-HT concentrations in blood and, in turn, induce an increase in blood calcium concentration. In this study, 20 Holstein dairy cows were randomly assigned to 2 experimental groups. Both groups received a daily i.v. infusion of 1 L of either 0.9% NaCl (C group; n = 10) or 0.9% NaCl containing 1 mg of 5-HTP/kg of BW (5-HTP group, n = 10). Infusions started d 10 before the estimated parturition and ceased the day of parturition, resulting in at least 4 d of infusion (8.37 ± 0.74 d of infusion). Until parturition, blood samples were collected every morning before the infusions, after parturition samples were taken daily until d 7, and a final sample was collected on d 30. Milk yield was recorded during this period. No differences between groups were observed for blood glucose, magnesium, and β-hydroxybutyrate. Cows receiving the 5-HTP infusion showed an increase in fatty acid concentrations from d -3 to -1 before parturition. Serum 5-HT concentrations were increased at d -4 related to parturition until d 5 postpartum in the 5-HTP group compared with the C group. In addition, cows from the 5-HTP group had increased 5-HT concentrations in colostrum, but not in mature milk, on d 7 postpartum. Serum calcium concentrations decreased in both groups around parturition; however, calcium remained higher in the 5-HTP group than in controls, with a significant difference between groups on d 1 (1.62 ± 0.08 vs. 1.93 ± 0.09 mmol/L in control and 5-HTP groups, respectively) and d 2 (1.83 ± 0.06 vs. 2.07 ± 0.07 mmol/L in control and 5-HTP groups, respectively). Additionally, colostrum yield (first milking) was lower in the 5-HTP group compared with the C group, but without consequences on colostrum IgG concentrations. Milk yield did not differ between groups during the rest of the experiment. The study data were consistent with the concept that infusion of 5-HTP to dairy cows increases blood 5-HT concentrations, which in turn is a significant regulatory component in the chain of effectors that affect calcium status around parturition, hence the occurrence of clinical or subclinical hypocalcemia.

Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period

Common health problems observed during peripartum include milk fever, mastitis, fatty liver disease, ketosis, dystocia, retained placenta, metritis, hypomagnesaemia and abomasal displacements. The increased incidence of health problems observed during the periparturient period can be partly attributed to suboptimal immune responses. Factors contributing to decreased periparturient immunity include the act of parturition itself, impaired leukocytic activity, effects of colostrogenesis and lactogenesis, and associated hypocalcemia and negative energy balance. Nutritional and other management strategies represent a relevant short-term strategy aimed at improving the health and welfare of the transitioning cow. Additionally, it is important to consider improving the health of dairy herds through the genetic selection of animals with enhanced robustness by identifying those with superior disease resistance or resilience in the face of infection. As a consequence these animals are better able to cope with the production and environmental stresses. These may provide long-term selection strategies for improving the health and welfare of the transitioning cow particularly when combined with sound management practices, allowing dairy cattle to reach their full genetic potential.

Invited review: Opportunities for genetic improvement of metabolic diseases

Metabolic disorders are disturbances to one or more of the metabolic processes in dairy cattle. Dysfunction of any of these processes is associated with the manifestation of metabolic diseases or disorders. In this review, data recording, incidences, genetic parameters, predictors, and status of genetic evaluations were examined for (1) ketosis, (2) displaced abomasum, (3) milk fever, and (4) tetany, as these are the most prevalent metabolic diseases where published genetic parameters are available. The reported incidences of clinical cases of metabolic disorders are generally low (less than 10% of cows are recorded as having a metabolic disease per herd per year or parity/lactation). Heritability estimates are also low and are typically less than 5%. Genetic correlations between metabolic traits are mainly positive, indicating that selection to improve one of these diseases is likely to have a positive effect on the others. Furthermore, there may also be opportunities to select for general disease resistance in terms of metabolic stability. Although there is inconsistency in published genetic correlation estimates between milk yield and metabolic traits, selection for milk yield may be expected to lead to a deterioration in metabolic disorders. Under-recording and difficulty in diagnosing subclinical cases are among the reasons why interest is growing in using easily measurable predictors of metabolic diseases, either recorded on-farm by using sensors and milk tests or off-farm using data collected from routine milk recording. Some countries have already initiated genetic evaluations of metabolic disease traits and currently most of these use clinical observations of disease. However, there are opportunities to use clinical diseases in addition to predictor traits and genomic information to strengthen genetic evaluations for metabolic health in the future.

Detection of Nonesterified (Free) Fatty Acids in Bovine Serum: Comparative Evaluation of Two Methods

A method comparison study for the determination and quantitation of nonesterified fatty acids (NEFAs) in serum, using the commercial “NEFA C” enzymatic test kit, was performed using the spectrophotometric method recommended by the manufacturer and a modified procedure optimized for the use of a microplate reader, a 96-well microtiter plate, and small sample volumes (10 μl). Linearity, sensitivity, and precision using the test kit were determined for each method of detection. The assay was linear from 0 to 1.97 mEq/liter for both procedures, and the limits of detection were determined to be 0.22 (±0.074) and 0.05 (±0.002) mEq/liter for the spectrophotometer and microplate reader, respectively. Pairs of measurements for bovine serum samples were compared and evaluated by a mean difference plot method and not regression analysis, a method that has been shown to be inappropriate for method comparison studies. The difference plot was used to evaluate the systematic bias between the 2 methods. Random error is reported on the basis of SD differences, and “limits of agreement” are used to describe the maximum differences likely to occur between the 2 methods. Results suggest that the microplate reader method can be used reliably in place of the recommended spectrophotometric method. The microplate reader method is preferred because of its high throughput capabilities, simultaneous analysis of all the standards and samples, use of small sample and reagent volumes, and reduction in labor requirements and costs.

Invited review: Role of bacterial endotoxins in the etiopathogenesis of periparturient diseases of transition dairy cows

The dairy industry continues to suffer severe economic losses due to the increased disease incidence cows experience during the transition period. It has long been the classical view that the major contributing factor to the development of these periparturient diseases is the considerable increase in nutritional demands for milk production. This classical view, however, fails to account for the substantial correlation between both metabolic and infectious diseases and the detrimental effects that can occur with the provision of high-energy diets to support these nutritional demands. Currently, increasing evidence implicates bacterial endotoxins in the etiopathology of most periparturient diseases. Bacterial endotoxins are components of the outer cell wall of gram-negative and gram-positive bacteria that are highly immunostimulatory and can trigger proinflammatory immune responses. The ability of endotoxins to translocate from the mucosal tissues, including the gastrointestinal tract, mammary gland, and uterus, into the systemic circulation has been observed. Once they have entered the circulation, endotoxins potentially contribute to disease either directly, through eliciting an inflammatory response, or indirectly through other factors such as the overreaction of the natural protective mechanisms of the host. Although the evidence implicating a role of endotoxins in the pathogenesis of transition diseases continues to grow, our current knowledge of the host response to mucosal endotoxin exposure and pathogenic mechanisms remain largely unknown. Developing our understanding of the connection between endotoxemia and dairy cattle disease holds significant potential for the future development of preventative measures that could benefit the productivity of the dairy industry as well as animal welfare.

Administration of early post-partum oral drench in dairy cows: effect on metabolic profile

<p>Some prophylactic treatments have been proposed in high-yielding dairy cattle in order to minimize the effects of negative energy balance and some disturbances such as hypocalcaemia and ketosis. The objective of this study was to evaluate the effects of two doses of Drench within 24 h after calving on the metabolic profile and prevention of ketosis. A total of 48 cows from a herd in Rio Grande do Sul state (southern Brazil) was used in the study. The animals were randomly selected and treated orally with Drench (N= 32, propylene glycol, electrolytes and choline in 40 L of water) and water (N= 16) used as control. Blood samples were collected by blood coccygeal venipuncture through a vacutainer plain system tubes. Biochemical determinations were performed in serum (albumin, urea, cholesterol, triglycerides, non-esterified fatty acids -NEFA-, calcium, phosphorus, magnesium, aspartate transaminase -AST- and gammaglutamyl-transferase -GGT-) and a cow-side determination of beta-hydroxybutyrate (BHB) was performed using the Abbot blood Precision Xtra system. All cows in the experiment had their milk production controlled. The Drench treatment produces a tendency to a better milk yield (32.5 vs 29.6 L/cow/day) and helps to prevent subclinical ketosis, as indicated by a lesser prevalence of subclinical ketosis (29.7 vs 37.2%) and mean values of BHB (1.19 vs 1.27 mmol/L) as well as a lesser lipolysis as indicated by NEFA values (509 vs 1.560 µmol/L).  The other components of the metabolic profile did not have substantial effects between treatments. In short, on the conditions of the present work, the Drench treatment is an effective management tool for prevention of subclinical ketosis and severe lipolysis.</p>

Metabolic Profile and Inflammatory Responses in Dairy Cows with Left Displaced Abomasum Kept under Small-Scaled Farm Conditions

Simple Summary

This research established an association between lactation number and milk production and metabolic and inflammatory responses in high-producing dairy cows affected by left abomasal displacement in small-scaled dairy farms. The study showed metabolic alterations, liver damage, and inflammation in the sick cows, which were further exacerbated with increasing lactation number and milk yield of the cows.

Abstract

Left displaced abomasum (LDA) is a severe metabolic disease of cattle with a strong negative impact on production efficiency of dairy farms. Metabolic and inflammatory alterations associated with this disease have been reported in earlier studies, conducted mostly in large dairy farms. This research aimed to: (1) evaluate metabolic and inflammatory responses in dairy cows affected by LDA in small-scaled dairy farms; and (2) establish an association between lactation number and milk production with the outcome of metabolic variables. The cows with LDA had lower serum calcium (Ca), but greater concentrations of non-esterified fatty acids (NEFA) and beta-hydroxy-butyrate (BHBA), in particular when lactation number was >2. Cows with LDA showed elevated levels of aspartate aminotransferase, glutamate dehydrogenase, and serum amyloid A (SAA), regardless of lactation number. In addition, this study revealed strong associations between milk yield and the alteration of metabolic profile but not with inflammation in the sick cows. Results indicate metabolic alterations, liver damage, and inflammation in LDA cows kept under small-scale farm conditions. Furthermore, the data suggest exacerbation of metabolic profile and Ca metabolism but not of inflammation and liver health with increasing lactation number and milk yield in cows affected by LDA.

Avaliação do perfil metabólico de vacas da raça Holandesa durante o período de transição

O período de transição é um momento de grande desafio para vacas de aptidão leiteira, uma vez que, a maioria dos problemas metabólicos ocorre nesta fase podendo prejudicar toda a expectativa de produção durante a lactação, resultando em impacto econômico significativo para fazendas de produção de leite. Este trabalho teve como objetivo avaliar o perfil metabólico de vacas da raça Holandesa durante o período de transição. Doze vacas Holandesas foram avaliadas, três semanas pré-parto até três semanas pós-parto, em sistema free-stall, localizado em Inhaúma, Minas Gerais, no período de outubro a dezembro de 2012. Avaliou-se o perfil metabólico através da concentração sérica de ácidos graxos não esterificados (AGNE), beta hidroxibutirato (BHBA), colesterol (COLES), proteína total (PT), albumina (ALB), cálcio, fósforo, magnésio bem como a atividade sérica das enzimas aspartato transaminase (AST) e lactato desidrogenase (LDH). As concentrações séricas de AGNE e BHBA foram diferentes entre o pré-parto e pós-parto (p<0,05). Observou-se diminuição na concentração de COLES com a aproximação do parto com posterior aumento (p<0,05). As concentrações séricas dos minerais, PT e ALB não apresentaram diferenças (p>0,05) no período avaliado. A atividade enzimática de AST e LDH foram maiores no período pós-parto (p<0,05). A avaliação do perfil metabólico é uma importante ferramenta de monitoramento e, na situação estudada, demonstrou alterações do perfil energético das vacas entre os períodos pré e pós-parto, relacionadas provavelmente a diminuição da ingestão de alimentos. A luz dos resultados do perfil metabólico, o rebanho avaliado possui pequeno risco para a ocorrência de enfermidades no pós-parto relacionadas ao período de transição

Diseases, reproductive performance, and changes in milk production associated with subclinical ketosis in dairy cows: a meta-analysis and review

Many studies have shown that subclinical ketosis (SCK) is associated with an increased risk of developing various diseases, reproductive disorders, and changes in milk production. The present work aims at producing an overview between this disorder and theses outcomes. A meta-analysis of the literature, including 131 different models from 23 papers, or a review when the literature was scarce was conducted. For each outcome, the odds ratio (OR), relative risk, or hazard ratio was presented for various moderators to reduce heterogeneity among the studies. The raw change in milk production associated with SCK was estimated and adjusted, taking into consideration the outcomes known to interact with milk production during the peripartum period. The results showed that 2 main categories of moderators had a significant effect on the adjusted risk. First, the adjustment made by defining SCK as (1) β-hydroxybutyrate concentration >1.4 mM, (2) nonesterified fatty acid (NEFA) concentration >0.4 mM prepartum, or (3) NEFA concentration >1.0 mM postpartum corrected the underestimated risk (despite low significance). This is because several trials reported the relevant risks using lower thresholds for the β-hydroxybutyrate or NEFA values. Using a low threshold leads to lower risk of disease compared with using a high threshold. Second, the correction produced using the polyfactorial terms corrected the overestimation of risk because many trials reported only univariable models. The relative risk or OR (95% confidence interval) related to abomasal displacement, clinical ketosis, early culling and death, metritis, placental retention, clinical mastitis, lameness, and a doubling of the SCC in cases with SCK were 3.33 (2.60-4.25), 5.38 (3.27-8.83), 1.92 (1.60-2.30), 1.75 (1.54-2.01), 1.52 (1.20-1.93), 1.61 (1.24-2.09), 2.01(1.64-2.44), and 1.42 (1.26-1.60), respectively. The precision level of the estimate depended on the outcome. The direct mean ± standard deviation of the 305-d milk losses associated with SCK were 251 ± 73 kg after adjusting for abomasal displacement, clinical ketosis, metritis, and placental retention. The OR (95% confidence interval) for first service calving risk in cases of SCK was 0.67 (0.53-0.83). The calving-to-first-service interval was 8 d longer and the calving-to-conception interval was 16 to 22 d longer in cows with SCK. The relationships among the different reproductive indicators were quantified in only 1 or 2 trials. The present work highlights the need to conduct further studies on the associations between SCK and the risks of diseases, changes in milk production, and reproductive parameters.

Characteristics of fluid composition of left displaced abomasum in beef cattle fed high-starch diets

To clarify the pathophysiology of left displaced abomasum (LDA), beef cattle fed high-starch diets were examined. The abomasal pH in beef cattle with LDA was lower than that in non-LDA reference animals (data from beef cattle at an abattoir), suggesting that it facilitated acidity. Bacteriological examinations of the abomasal fluid in cattle with LDA revealed the presence of Pseudomonas spp., Clostridium spp. and Candida spp., presumably reflecting the accelerated influx of ruminal fluid into the abomasum. Biochemical analyses of serum revealed that LDA cattle had higher lactic acid and lower vitamin A and E levels than non-LDA reference animals. These results indicate that beef cattle with LDA may suffer from vitamin A and E deficiencies due to maldigestion of starch and the high acidity of abomasal fluid.

Non-esterified fatty acids activate the AMP-activated protein kinase signaling pathway to regulate lipid metabolism in bovine hepatocytes

Non-esterified fatty acids (NEFAs) act as signaling molecules involved in regulating genes expression to modulate lipid metabolism. However, the regulation mechanism of NEFAs on lipid metabolism in dairy cows is unclear. The AMP-activated protein kinase (AMPK) signaling pathway plays a key role in regulating hepatic lipid metabolism. In vitro, bovine hepatocytes were cultured and treated with different concentrations of NEFAs and AMPKα inhibitors (BML-275). NEFAs increased AMPKα phosphorylation through up-regulating the protein levels of liver kinase B1. Activated AMPKα increased the expression and transcriptional activity of peroxisome proliferator-activated receptor α (PPARα). NEFAs also directly activate the PPARα independent of AMPKα. Activated PPARα increased the lipolytic genes expression to increase lipid oxidation. Furthermore, activated AMPKα inhibited the expression and transcriptional activity of the sterol regulatory element-binding protein 1c and carbohydrate responsive element-binding protein, which reduced the expression of lipogenic genes, thereby decreasing lipid synthesis. Activated AMPKα phosphorylated and inhibited acetyl-CoA carboxylase and increased carnitine palmitoyltransferase-1 activity, which increased lipid oxidation. Consequently, the triglyceride content in the NEFAs-treated hepatocytes was significantly decreased. These results indicate that NEFAs activate the AMPKα signaling pathway to increase lipid oxidation and decrease lipid synthesis in hepatocytes, which in turn, generates more ATP to relieve the negative energy balance in transition dairy cows.

Dietary energy density in the dry period on the metabolic status of lactating cows

The aim of the study was to investigate the effect of different energy concentrations in the isonitrogenous diet fed during the dry period on postpartum health, fertility and blood variables. Forty Holstein multiparous cows were dried 56 days before the expected day of calving and assigned to group (M) with moderate energy concentrations of 0.69 UFL/kg DM or to the low-energy group (L) with energy density of 0.61 UFL/kg DM. From the 7d before the expected day of calving until the 21d of lactation, all the cows were fed the same fresh transition diet (0.82 UFL/kg DM). From the 22d to the 90d of lactation, all the cows received the same highest energy-density lactation diet (0.90 UFL/kg DM). During the dry period the decline of BCS in groups M and L were 0.07 and 0.12 units respectively. The average decrease of BCS from calving to 56 d of lactation were the same in both experimental groups (0.21 BCS). The first-service conception rate tended to be higher in the M group. Insulin-like growth factor-1, glucose, beta-hydroxybutyric acid, non-esterified fatty acid, thyroxine serum concentrations prepartum and 3 and 5d postpartum were not significantly affected by the treatment in the dry period.