Data from 1,010 lactating lactating, predominately component-fed Holstein cattle from 25 predominately tie-stall dairy farms in southwest Ontario were used to identify objective thresholds for ...defining hyperketonemia in lactating dairy cattle based on negative impacts on cow health, milk production, or both. Serum samples obtained during wk 1 and 2 postpartum and analyzed for β-hydroxybutyrate (BHBA) concentrations that were used in analysis. Data were time-ordered so that the serum samples were obtained at least 1 d before the disease or milk recording events. Serum BHBA cutpoints were constructed at 200μmol/L intervals between 600 and 2,000μmol/L. Critical cutpoints for the health analysis were determined based on the threshold having the greatest sum of sensitivity and specificity for predicting the disease occurrence. For the production outcomes, models for first test day milk yield, milk fat, and milk protein percentage were constructed including covariates of parity, precalving body condition score, season of calving, test day linear score, and the random effect of herd. Each cutpoint was tested in these models to determine the threshold with the greatest impact and least risk of a type 1 error. Serum BHBA concentrations at or above 1,200μmol/L in the first week following calving were associated with increased risks of subsequent displaced abomasum odds ratio (OR)=2.60 and metritis (OR=3.35), whereas the critical threshold of BHBA in wk 2 postpartum on the risk of abomasal displacement was ≥1,800μmol/L (OR=6.22). The best threshold for predicting subsequent risk of clinical ketosis from serum obtained during wk 1 and wk 2 postpartum was 1,400μmol/L of BHBA (OR=4.25 and 5.98, respectively). There was no association between clinical mastitis and elevated serum BHBA in wk 1 or 2 postpartum, and there was no association between wk 2 BHBA and risk of metritis. Greater serum BHBA measured during the first and second week postcalving were associated with less milk yield, greater milk fat percentage, and less milk protein percentage on the first Dairy Herd Improvement test day of lactation. Impacts on first Dairy Herd Improvement test milk yield began at BHBA ≥1,200μmol/L for wk 1 samples and ≥1,400μmol/L for wk 2 samples. The greatest impact on yield occurred at 1,400μmol/L (−1.88kg/d) and 2,000μmol/L (−3.3kg/d) for sera from the first and second week postcalving, respectively. Hyperketonemia can be defined at 1,400μmol/L of BHBA and in the first 2 wk postpartum increases disease risk and results in substantial loss of milk yield in early lactation.
A retrospective cohort study was performed with the objective of determining whether the serum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA), or calcium were ...associated with the risk of culling within 60 d in milk (DIM) in Holstein cows, and to establish thresholds for each metabolite that were predictive of increased culling risk. Data from 5,979 cows in Ontario (Canada) and several US states were obtained from 4 previously reported studies. For each metabolite and each of 3 sampling weeks (−1, +1, and +2 relative to calving), an optimal threshold was calculated based on having the maximum combined sensitivity (Se) and specificity (Sp) and used to categorize the serum concentrations into high and low risk groups. Logistic regression models were built for each metabolite and each week of sampling, as well as considering together all metabolites in wk −1 and wk +1 relative to calving. Cow was considered the experimental unit and herd as a random effect. Considered separately, precalving NEFA ≥0.4mmol/L odds ratio (OR)=1.8; 95% confidence interval (CI)=1.4 to 2.2, NEFA ≥0.8mmol/L in wk +1 relative to calving (OR=2.0; 95% CI=1.5 to 2.6) and NEFA ≥0.8mmol/L in wk +2 (OR=4.2; 95% CI=1.9 to 9.4 for cows in lactation 2; OR=2.1; 95% CI=1.4 to 3.3 for cows in lactation ≥3) were each associated with an increased risk of culling within the first 60 DIM. Similarly, BHBA ≥0.7mmol/L in wk −1 (OR=1.8; 95% CI=1.3 to 2.5), BHBA ≥1.2mmol/L in wk +1 (OR=1.8; 95% CI=1.4 to 2.2), and BHBA ≥1.6mmol/L in wk +2 (OR=3.2; 95% CI=1.6 to 6.4 for cows in lactation 2; OR=2.3; 95% CI=1.6 to 3.3 for cows in lactation ≥3) were each associated with an increased risk of culling within the first 60 DIM. Likewise, calcium ≤2.3mmol/L in wk −1 (OR=1.6; 95% CI=1.2 to 2.2), calcium ≤2.2mmol/L in wk +1 (OR=1.5; 95% CI=1.2 to 1.9), and calcium ≤2.3mmol/L in wk +2 (OR=2.3; 95% CI=1.1 to 3.1) were each associated with an increased risk of culling within the first 60 DIM. When all metabolites were analyzed together, serum NEFA and calcium concentrations in wk −1 and serum NEFA concentration in wk +1 remained in the models. In conclusion, elevated serum NEFA and BHBA concentrations and lower serum calcium concentrations within 1 wk before calving through 2 wk after calving were associated with an increased risk of culling in early lactation. Measuring the concentration of selected metabolites around parturition may help to develop monitoring and intervention strategies to prevent early culling in transition dairy cows.
The objectives of this observational study were to determine and compare diagnostic criteria for postpartum endometritis in dairy cows. Data generated from 1,044 Holstein cows (6 herds) enrolled in a ...randomized clinical trial were used. Cows were examined for endometritis at 35±3 d (exam 1) and 56±3 d (exam 2) after parturition, using endometrial cytology (cytobrush technique), vaginal discharge scoring (Metricheck device; Simcrotech, Hamilton, New Zealand), and cervical diameter measurement (transrectal palpation). Reproductive data were recorded until 200 d after parturition. Diagnostic criteria for cytological and clinical endometritis were determined based on detrimental effect on subsequent reproductive performance, using logistic regression and Cox proportional hazard models accounting for the effect of herd clustering. Comparison of diagnostic criteria was performed using endometrial cytology as reference test or by quantifying the agreement between diagnostic approaches. At exam 1, diagnostic criteria were ≥6% polymorphonuclear cells and mucopurulent or worse (purulent or foul) vaginal discharge for cytological and clinical endometritis, respectively. At exam 2, diagnostic criteria were ≥4% polymorphonuclear cells and mucopurulent or worse vaginal discharge for cytological and clinical endometritis, respectively. Cows were classified as having cytological endometritis only, clinical endometritis only, or both cytological and clinical endometritis. Prevalence at exam 1 was 13.5, 9.4, and 5.8% for cytological endometritis only, clinical endometritis only, and both cytological and clinical endometritis, respectively. The detrimental effects of cytological and clinical endometritis on reproductive performance were additive. Among cows with clinical endometritis, only 38 and 36% had cytological endometritis at exam 1 and exam 2, respectively. Combination of diagnostic criteria improved neither the accuracy for predicting cytological endometritis nor the agreement between cytological and clinical endometritis. Overall, these results suggested that cytological and clinical endometritis may represent different manifestations of reproductive tract disease. They also suggested that use of the terminology clinical endometritis may not be accurate and that purulent vaginal discharge may be more descriptive.
The objective of this observational field study was to validate the relationship of serum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and calcium with disease in ...early lactation across different management systems. Fifty-five Holstein freestall dairy herds located across the United States and Canada were selected and visited weekly for blood sample collection from 2,365 cows. Only diseases that were consistently recorded across herds and blood samples collected before the disease occurred were considered. Metabolite concentrations in serum in wk −1 relative to calving were considered as predictors of retained placenta (RP) and metritis, and metabolite concentrations in serum in wk −1 and wk +1 relative to calving were considered as predictors of displaced abomasum (DA). For each disease, each metabolite, and week of sampling in the case of DA, a critical threshold was calculated based on the highest combined sensitivity and specificity and used to categorize the serum concentrations into high and low risk categories. Multivariable logistic regression models were built for each disease of interest and week of sampling, considering cow as the experimental unit and herd as a random effect. Cows with precalving serum NEFA concentrations ≥0.3mEq/L were more likely to develop RP odds ratio (OR) = 1.8; 95% confidence interval (CI) = 1.3 to 2.6 and metritis (OR = 1.8; 95% CI=1.5 to 2.9) after calving than cows with lower NEFA concentrations. Precalving NEFA ≥0.5mEq/L (OR=2.4; 95% CI=1.5 to 3.7), postcalving NEFA ≥1.0mEq/L (OR=2.7; 95% CI=1.7 to 4.4), and postcalving calcium ≤2.2mmol/L (OR=3.1; 95% CI=1.9 to 5.0) were associated with subsequent risk of DA. In conclusion, elevated serum NEFA concentrations within 1 wk before calving were associated with increased risk of RP, metritis, and DA after calving. Serum NEFA and calcium concentrations in the 2 wk around calving in combination were associated with the risk of DA.
This paper describes some of the major points of progress and challenges in health management of dairy cattle in the last 25 yr. A selection of the leading contributors in the field is acknowledged. ...Specific advances in the areas of transition cow management, epidemiology, udder health, applied immunology, housing design, calf health, and health-monitoring tools are described. The greatest advances in dairy health in the last 25 yr have been the shifts to disease prevention, rather than treatment, as well as from focus on individual animals to groups and herds. A fundamental advancement has been recognition of the multifactorial nature of almost all diseases of importance in dairy cattle. Epidemiology has been a critical new tool used to describe and quantify the interconnected risk factors that produce disease. Another major advance has been redefining disease more broadly, to include subclinical conditions (e.g., subclinical mastitis, ketosis, rumen acidosis, and endometritis). This expansion resulted both from improved technology to measure function at the organ level and, just as importantly, from the evolution of the health management paradigm in which any factor that limits animal or herd performance might be considered a component of disease. Links between cattle and people through consideration of environmental or ecosystem health are likely to further expand the concept of disease prevention in the future.
Notable successes are decreases in the incidence of milk fever, clinical respiratory disease in adults, contagious mastitis, and clinical parasitism. There has also been improved protection through vaccination against coliform mastitis and bovine virus diarrhea. Since 1980, average herd size and milk production per cow have increased dramatically. Despite these increased demands on cows’ metabolism and humans’ management skills, the incidence of most common and important diseases has remained stable. Great progress has been made in understanding the biology of energy metabolism and immune function in transition dairy cows, the time at which the majority of disease occurs. Coupled with an emerging understanding of how best to provide for dairy cows’ behavioral needs, transition cow management promises to be the foundation for progress in maintenance and enhancement of the health of dairy cows in the next 25 yr.
The objective was to quantify the effect of postpartum uterine diseases on milk production and culling. Data from 2,178 Holstein cows in 6 herds enrolled in a randomized clinical trial were used. ...Milk production data from the first 4 Dairy Herd Improvement Association (DHIA) test-days and culling data from farm records were collected. Retained placenta (RP; ≥24 h after parturition) and metritis ≤20 d in milk (DIM) were diagnosed by farm managers using standardized definitions. Farms were visited weekly and cows were examined at 35 and 56 (±3) DIM using endometrial cytology (cytobrush device), vaginal discharge scoring (Metricheck device), and measurement of cervical diameter by transrectal palpation. Diagnostic criteria for cytological endometritis (CYTO) and purulent vaginal discharge (PVD) were established based on a detrimental effect on subsequent reproduction. Statistical analyses were performed using linear mixed models, logistic regression models, and Cox proportional hazard models, accounting for the effects of experimental treatments and herd clustering. Milk production and culling were the outcomes. Primiparous and multiparous cows were modeled separately for milk production. Milk production of primiparous cows was unaffected by uterine diseases. The effect of metritis on milk production was variable over time in multiparous cows: it decreased production per cow by 3.7 kg at the first DHIA test, but was not different at later tests. Retained placenta decreased milk production by 2.6 kg/d in multiparous cows through the first 4 DHIA tests. The projected effects of metritis and RP in multiparous cows were reductions of 259 kg and 753 kg over 305 DIM, respectively; these effects were additive. Neither CYTO nor PVD affected milk production. Culling risks at 30 and 63 DIM were unaffected by RP and metritis. Culling hazard up to 300 DIM was unaffected by RP, metritis, CYTO, or PVD, whether or not pregnancy status, milk production, and displaced abomasum were accounted for. Uterine disease decreased pregnancy rate, which was a substantial risk factor for culling; however, if affected cows became pregnant they were not at greater risk of culling.
The objectives of this randomized clinical trial were to determine whether the utilization of a multispecies probiotic bolus (MSP) in dairy calves with diarrhea led to a rapid resolution of diarrhea ...and improved average daily gain (ADG). Calves, from a convenience sample of dairy farms with diarrhea challenges, having fecal scores of ≥2 were randomly assigned to receive MSP or a placebo (PLB). The MSP bolus contained Pediococcus acidilactici, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, peptide extract, an enzyme blend, killed yeast extract, dried whey, and natural flavors (Revive, Partnar Animal Health, Ilderton, ON, Canada). The enrolled calves were fecal scored daily for 7 consecutive days and resolution of diarrhea was defined as having 2 consecutive days with a fecal score ≤1. Calves were also weighed at enrollment, 7, and 14 d following enrollment and ADG was calculated. A Cox proportional hazards model was built to investigate time to resolution of an abnormal fecal score. Two mixed linear regression models were created to evaluate the effect of treatment group on ADG in the first and second weeks following enrollment. A total of 148 calves were enrolled in the experiment and no differences were observed between the groups with respect to the age or weight at enrollment. The mean time to resolution of abnormal fecal score was 5.1 and 5.9 d in the MSP and PLB groups, respectively. In the Cox proportional hazards model, the calves in the MSP group had faster resolution of diarrhea when compared with the PLB group; however, an interaction between time from enrollment of the first calf and treatment group was present. No differences were found between the 2 groups with respect to ADG. This study demonstrates a multispecies probiotic and yeast bolus administered to calves at the onset of diarrhea reduced the duration of diarrhea; however, the clinical and economic relevance of this reduction requires further exploration.
The objective of this field study was to identify metabolic tests available in clinical practice that identified cows at increased risk of left displaced abomasum (LDA). A technician visited 1044 ...cows in 20 herds weekly from 1wk before expected calving until 1wk postpartum. Cows were assigned a body condition score and samples were collected at each visit for measurement of serum nonesterified fatty acids (NEFA), cholesterol, β-hydroxybutyrate (BHBA), glucose, urea, calcium, and phosphorus, and a milk sample was collected postpartum for measurement of BHBA. The probability of LDA was modeled with multivariable logistic regression accounting for clustering. There were 53 cases of LDA (incidence risk = 5.1%) and the median time of diagnosis was 11 d in milk. In cows with LDA, mean NEFA concentrations began to diverge from the mean in cows without LDA 14 d before calving, whereas mean serum BHBA concentrations did not diverge until the day of calving. Prepartum, only NEFA concentration was associated with risk of subsequent LDA. Between 0 and 6 d before calving, cows with NEFA concentration ≥0.5mEq/L were 3.6 times more likely to develop LDA after calving. For prospective application, among samples taken 4 to 10 d before expected calving, the optimum NEFA cut-point remained 0.5mEq/L. The sensitivity, specificity, and likelihood ratio (LR) were 46%, 82%, and 2.6, respectively. Between 1 and 7 d postpartum, retained placenta, metritis, and increasing serum concentrations of BHBA and NEFA were associated with increased risk of subsequent LDA. However, considered separately, postpartum serum BHBA was a more sensitive and specific test than NEFA concentration. The odds of LDA were 8 times greater in cows with serum BHBA ≥1200μmol/L (LR=3.5). Cows with milk BHBA concentration ≥200μmol/L were 3.4 times more likely to develop LDA. Serum calcium concentration was not associated with LDA. Strategic use of metabolic tests to monitor transition dairy cows should focus on NEFA in the last week prepartum and BHBA in the first week postpartum.
The objective was to examine the associations of peripartum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and calcium with milk production in early lactation and ...pregnancy at the first artificial insemination (AI) across different management systems. Fifty-five Holstein freestall dairy herds located across the United States and Canada were visited weekly for blood sample collection from 2,365 cows. For each week of sampling (from wk −1 through wk 3 relative to calving) and for each metabolite, serum concentrations were dichotomized at various thresholds to identify the thresholds with the best negative associations with milk production and pregnancy at first AI. These thresholds were used to categorize the serum concentrations into higher and lower risk categories. Repeated-measures ANOVA and multivariable logistic regression were conducted for milk production and pregnancy at the first AI data, respectively, considering cow as the experimental unit and herd as a random effect. In the week before calving, serum NEFA ≥0.5mEq/L, BHBA ≥600μmol/L, and calcium ≤2.1mmol/L were associated with 1.6 to 3.2 kg/d milk loss across the first 4 Dairy Herd Improvement Association (DHIA) milk tests. High levels of NEFA and BHBA in wk 1 and 2 after calving (≥0.7 and ≥1.0mEq/L for NEFA, and ≥1,400 and ≥1,200μmol/L for BHBA), and low levels of calcium (≤2.1mmol/L) in wk 1, 2 and 3 after calving were associated with milk loss at the first DHIA milk test. Serum concentrations of NEFA and BHBA were not associated with pregnancy at first AI in any sampling week, whereas calcium <2.2 to 2.4mmol/L from wk 1 through wk 3 postpartum were associated with reduced pregnancy at first AI. In conclusion, high serum concentrations of NEFA, BHBA, and low concentrations of calcium around parturition were associated with early lactation milk loss, and low calcium concentration around parturition was associated with impaired early lactation reproduction.
The objective of this cross-sectional herd-level study was to assess the association of calf management practices on source dairy farms with mortality risk on veal farms. From April to October 2016, ...52 source dairy farms supplying male calves to 2 veal operations were visited once. A questionnaire was administered that covered all areas of calf management, calves between 1 and 10 d of age were examined using a standardized health scoring system, and blood was taken to evaluate passive transfer of immunoglobulins. The mortality risk for calves from each dairy farm was calculated based on the number of male calves sold from the dairy farm and that died during 2016 at the veal operations. The mean mortality risk was calculated for both veal farms and, based on the veal facility-adjusted mortality risk, dairy farms were classified as high- or low-mortality source farms. Using the information gathered at the 52 source dairy farms, a logistic regression model was used to assess factors associated with being a high-mortality source farm. Suppliers to veal farm 1 had a mean mortality risk of 9.6% and suppliers to veal farm 2 had a mean mortality risk of 4.2%. The lower mortality risk at veal farm 2 was partially influenced by a shorter period of observation. Of the 182 calves examined during the single visit to the source dairy farms, 41% of male calves and 29% of female calves had at least one identifiable health abnormality. The risk of failure of passive transfer on source dairy farms was low, with only 13% of calves tested having <10 mg of IgG/mL of serum. The subset of calves examined at the source dairy farm was not followed prospectively to the veal farms. Using a tube feeder or pail to feed colostrum, bedding male calves on wood shavings or chopped straw at the source dairy farm, and the herd veterinarian not routinely and actively inquiring about the health and performance of calves during regular herd visits were significantly associated with the farm being classified as a high-mortality source dairy farm. Checking the calving pen at an interval of every 3 h or more during the day was associated with a lower probability of being classified as a high-mortality source dairy farm. The results of this study suggest that there are management practices on the source farm that contribute to the risk of mortality on veal farms.
PDF
