Validity of luminometry and bacteriological tests for diagnosing intramammary infection at dry-off in dairy cows.

The objective of this cross-sectional study was to estimate the validity of laboratory culture, Petrifilm and Tri-Plate on-farm culture systems, and luminometry to correctly identify IMI at dry-off in dairy cows, considering all tests as imperfect. From September 2020 until December 2021, we collected composite milk samples from cows before dry-off and divided them into 4 aliquots for the luminometry test, the Petrifilm (aerobic count), the Tri-Plate, and the laboratory culture. While we assessed multiple thresholds of relative light units (RLU) for the luminometry, we used thresholds of ≥100 cfu/mL for the laboratory culture, ≥ 50 cfu/mL for the Petrifilm, and ≥1 cfu for the Tri-Plate. We fitted Bayesian latent class analysis (LCA) models to estimate the sensitivity (Se) and specificity (Sp) for each test to identify IMI, with 95% credibility interval (BCI). Using different prevalence measures (0.30, 0.50, and 0.70), we calculated the predictive values (PV) and misclassification cost terms (MCT) at different false-negative to false-positive ratios (FN:FP). A total of 333 cows were enrolled in the study from one commercial Holstein herd. The validity of the luminometry was poor for all thresholds, with Se of 0.51 (95% BCI = 0.43-0.59) and Sp of 0.38 (95% BCI = 0.26-0.50) when using a threshold of ≥150 RLU. The laboratory culture had Se of 0.93 (95% BCI = 0.85-0.98) and Sp of 0.69 (95% BCI = 0.49-0.89), the Petrifilm had Se of 0.91 (95% BCI = 0.80-0.98) and Sp of 0.71 (95% BCI = 0.51-0.90), and the Tri-Plate had Se of 0.65 (95% BCI = 0.53-0.82) and Sp of 0.85 (95% BCI = 0.66-0.97). Bacteriological tests had good PVs, with comparable positive PV for all 3 tests, but lower negative PV for the Tri-Plate compared with the laboratory culture and the Petrifilm. For a prevalence of IMI of 0.30, all 3 tests had similar MCT, but for prevalence of 0.50 and 0.70, the Tri-Plate had higher MCT in scenarios where leaving a cow with IMI untreated is considered to have greater detrimental impacts than treating a healthy cow (i.e., FN:FP of 3:1). Our results showed that the bacteriological tests have adequate validity to diagnose IMI at dry-off, but the luminometry does not. We concluded that, while luminometry is not useful to identify IMI at dry-off, the Petrifilm and Tri-Plate tests performed similarly to the laboratory culture, depending on the prevalence and the importance of the FP and FN results.

Herd-level associations between the proportion of elevated prepartum nonesterified fatty acid concentrations and postpartum diseases, reproduction, or culling on dairy farms.

The objectives of this herd-level prospective observational cohort study were to describe the proportion of cows with elevated prepartum nonesterified fatty acid concentrations (PropElevNEFA) in dairy herds and to assess the herd-level associations between PropElevNEFA and postpartum diseases, reproductive performance, and culling. From November 2018 to December 2020, a convenience sample of 49 herds was enrolled in this study. Blood sampling (16 to 29 cows per herd) was performed during the week before and during the 2 wk following calving to quantify the concentration of nonesterified fatty acids (NEFA) and ß-hydroxybutyrate acids (BHBA), respectively. Elevated NEFA was defined as ≥280 µmol/L and hyperketonemia as BHBA ≥1.4 mmol/L. Retained placenta, metritis, purulent vaginal discharge, endometritis, and mastitis were diagnosed on-farm following standardized definitions, and success at first artificial insemination (AI) and culling events were recorded. The associations between PropElevNEFA and each individual disease, success at first AI, and culling were evaluated using Bayesian aggregated binomial regression models with weakly informative priors, from the which odds ratio (OR) and the 95% credible intervals (BCI) were obtained. A total of 981 cows were included in the statistical analyses representing 16 to 29 (median = 19) cows per herd. Cows were enrolled in the prepartum period of their first to tenth (median = third) lactation, and 41% of them had an elevated prepartum NEFA concentration. At the herd level, PropElevNEFA varied between 11% and 78% (median = 39%). The odds of metritis (OR = 1.37, 95% BCI = 1.13-1.67) increased for every 10-point increase in PropElevNEFA, whereas the odds of success at first AI decreased (OR = 0.69, 95% BCI = 0.59-0.80). The PropElevNEFA was not associated with the other tested diseases or culling. Our results suggest that the herd-level proportion of cows having elevated prepartum NEFA concentrations is associated with metritis and poor success at first AI in dairy herds.

Randomized controlled trial assessing the impact of a combined treatment of insulin glargine and propylene glycol on the resolution of hyperketonemia and milk production in postpartum dairy cows.

Multiple treatments for hyperketonemia have been studied, and although propylene glycol has been the most constantly reported as successful in mitigating the effects of this condition, a recent study showed that a subpopulation of cows affected by hyperketonemia and hypoglycemia could benefit from a combined treatment of propylene glycol and insulin glargine. The objective of the present study was to assess the effect of this combination on the time-to-hyperketonemia resolution, and on milk production following the initial treatment. A randomized controlled trial was conducted on 2 commercial farms on which postpartum exams were conducted twice a week. Cows naturally affected by both hyperketonemia [ß-hydroxybutyrate (BHB) ≥ 1.4 mmol/L] and hypoglycemia (glucose <2.2 mmol/L) were enrolled and randomly assigned to receive 2 mL of placebo (physiological saline) subcutaneously (PBO), or to receive 2 mL of insulin glargine (200 IU) subcutaneously (INS). Cows in both groups also received 300 g of propylene glycol orally for 3 d. Time-to-hyperketonemia resolution (return to BHB <1.4 mmol/L) and daily milk production following the initial treatment were compared between groups using Cox proportional hazard and mixed linear regression models, respectively. A total of 248 cows between 1 and 30 d in milk (median = 16) were enrolled in the trial from January 2018 to February 2022. Cows were of first (32.3%; n = 80/248), second (32.3%; n = 80/248), or third or greater (35.4%; n = 88/248) parity. The overall time-to-hyperketonemia resolution was not different between treatments, but there was a 2-way interaction between treatment group and parity. Primiparous cows had a shorter time-to-resolution in the INS group than in the PBO group; no difference was observed between treatment groups for older cows. The overall milk production of cows in the INS group was 3.4 kg higher than cows in the PBO group during the 14 d after enrollment. There was a 2-way interaction between treatment group and parity. Primiparous cows in the INS group produced 5.3 kg more milk daily than primiparous cows in the PBO group; no effect of treatment was found for older cows. These results suggest that cows affected simultaneously by hyperketonemia and hypoglycemia benefited from a combined treatment of propylene glycol and insulin glargine to improve subsequent milk production and that the effect primarily came from the positive effect in primiparous cows. Time-to-hyperketonemia resolution was also improved in primiparous cows but not in older cows.

Keeping profitable cows in the herd: A lifetime cost-benefit assessment to support culling decisions.

Increasing the productive lifespan of dairy cows is important to achieve a sustainable dairy industry, but making strategic culling decisions based on cow profitability is challenging for farmers. The objective of this study was to carry out a lifetime cost-benefit analysis based on production and health records and to explore different culling decisions among farmers. The cost-benefit analysis was conducted for 22 747 dairy cows across 114 herds in Quebec, Canada for which feed costs and the occurrence of diseases were reported. Costs and revenues related to productive lifespan were compared among cohorts of cows that left their respective herd at the end of their last completed lactation or stayed for a complete additional lactation. Hierarchical clustering analysis was carried out based on costs and revenues to explore different culling decisions among farmers. Our results showed that the knowledge of lifetime cumulative costs and revenues was of great importance to identify low-profitable cows at an earlier lactation, while only focusing on current lactation costs and revenues can lead to an erroneous assessment of profitability. While culling decisions were mostly based on current lactation costs and revenues and disregarded the occurrence of costly events on previous lactations, there was variation among farmers as we identified three different culling decision clusters. Monitoring cumulative costs and revenues would help farmers to identify low-profitable cows at an earlier lactation and make the decision to increase herd productive lifespan and farm profitability by keeping the most profitable cows.

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.

Development of a multivariable prediction model to identify dairy calves too young to be transported to auction markets in Canada using simple physical examination and body weight.

Calves born on Eastern Canadian dairy farms that are not kept in the herds are traditionally sold through auction markets and are raised for meat purposes such as veal calves. Since February 2020, a new Canadian federal regulation has forbidden calves <9 d old to be sold through auction markets. However, in the absence of a real-time birth registry consultation system, it would be of interest to look for predictors that could be associated with age to allow identification of calves too young to be transported. In the current retrospective cross-sectional study, 1,178 calves with a declared birth date (411 calves aged <9 d old; 34.9%) were assessed in 2 large Québec auction sites. Easy-to-record covariates [body weight (BW), breed phenotype, and presence of an umbilical cord remnant] as well as other clinical signs (umbilical swelling, enlargement, umbilical pain, wet umbilicus, skin tent, sunken eyes, ocular and nasal secretion, and hide cleanliness) were assessed. Two logistic regression models using age as a dichotomous dependent variable (<9 d old vs ≥9 d old) were built. The first model (model 1) considered all covariates, which were selected after univariable analyses and a backward stepwise selection process, whereas a more pragmatic model (model 2) only included the 3 easy-to-record variables (i.e., BW, breed, umbilical cord). Both models had similar accuracy to detect calves <9 d old (sensitivity of 38.4 and 37.5%, and specificity of 85.7 and 84.6% for model 1 and 2, respectively). Model 2 was subsequently more specifically studied as it employs a faster and easier assessment. Decision thresholds were tested for their robustness based on misclassification cost term (MCT) analysis with various prevalence of calves <9 d old and various costs of false-negative:false-positive ratio. Despite statistical significance, model accuracy, even if refined with MCT analysis, was limited at the individual level, showing the limits of using physical signs and BW or their combination as a reliable proxy of age. The sensitivity of these models to find calves <9 d old was not to be used for monitoring compliance with the Canadian federal regulation. The relatively high model specificity may help to use this model as a rule-in test (i.e., targeting positive calves for further investigation) rather than a rule-out test (due to its low sensitivity).

The hidden cost of disease: II. Impact of the first incidence of lameness on production and economic indicators of primiparous dairy cows.

Lameness is a persistent and underreported health and welfare problem in the dairy industry, resulting in reduced cow performance and profitability as well as early culling. The study objectives were (1) to quantify the impact of the first instance of lameness, at different stages of lactation, on production and economic performance, and (2) to further quantify the impacts of the first instance of lameness when only cows that remain in the herd for at least 100 d in milk (DIM) and those that remain for 305 DIM are included in the analysis. A retrospective longitudinal study was conducted using pre-existing data from animal health records and Dairy Herd Improvement Association records. Data were edited based on selected inclusion criteria, yielding a data set containing records from 15,159 first-lactation Holstein cows from 120 herds with year of first calving between 2003 and 2014. Lame cows were assigned to 1 of 4 groups based on when in the lactation the first event of lameness occurred: transition (1-21 DIM), early lactation (22-100 DIM), mid-lactation (101-200 DIM), or late lactation (201+ DIM). Mid- and late-lactation lame cows were also stratified by cumulative milk yield before the lameness event. Healthy cows (i.e., no recorded lameness event) were randomly assigned for each lactation stage, with mid-lactation healthy and late-lactation healthy cows similarly stratified. Production performance (cumulative milk, fat, and protein yield) and economic performance [milk value, margin over feed cost (MOFC), and gross profit] were analyzed using a mixed model with herd as a random effect. Cumulative milk yields were 811 to 1,290 kg lower for lame cows than for healthy cows, with milk component yields undergoing similar reductions. Reductions in milk yield contributed to losses in milk value (-Can$527 to -Can$1,083; -US$419 to -US$862) and MOFC (-Can$510 to -Can$774; -US$406 to -US$616). Higher losses were reported using gross profit (-Can$753 to -Can$1,052; -US$599 to -US$837), which includes all lameness-related costs. Production and performance losses were smaller when 100 DIM and 305 DIM thresholds were applied (i.e., exclusion of cows culled before 100 and 305 DIM, respectively), however, mid- and late-lactation lame cows maintained high levels of significant losses for all 6 variables analyzed. Lameness also led to higher levels of culling, masking losses for transition and early-lactation lame cows in the 305-DIM analysis. Increasing producer understanding of the costs associated with lameness not only serves to provide insight to producers for more informed culling decisions, but may also help producers weigh the costs of adopting new methods and technologies targeted at reducing on-farm lameness.

The hidden cost of disease: I. Impact of the first incidence of mastitis on production and economic indicators of primiparous dairy cows.

Mastitis is a highly prevalent disease, which negatively affects cow performance, profitability, welfare, and longevity. The objectives of this study were (1) to quantify the impact of the first instance of mastitis, at different stages of lactation, on production and economic performance, and (2) to further quantify the impact of the first instance of mastitis when only cows that remain in the herd for at least 100 d in milk (DIM) and those that remain for 305 DIM are included in the analysis. A retrospective longitudinal study was conducted using data from existing animal health record files and Dairy Herd Improvement records. After editing based on selected inclusion criteria and completeness of health records, data consisted of records from first-lactation Holstein cows, from 120 herds, that calved for the first time between 2003 and 2014, inclusive. Mastitic cows were assigned to 1 of 4 groups based on when in the lactation the first event of mastitis occurred: transition (1-21 DIM), early lactation (22-100 DIM), mid lactation (101-200 DIM), or late lactation (201+ DIM). Mid-lactation and late-lactation mastitic cows were also stratified by cumulative milk yield before the mastitis event. Healthy cows (i.e., no recorded mastitis event) were randomly assigned for each lactation stage, with mid-lactation healthy and late-lactation healthy cows similarly stratified. Production performance (cumulative milk, fat, and protein yield) and economic performance [milk value, margin over feed cost (MOFC), and gross profit] were analyzed using a mixed model with herd as a random effect. Significant losses in cumulative milk yield (-382 to -989 kg) and correspondingly lower fat and protein yields were found in mastitic cows, with transition and late-lactation mastitic cows having the highest losses. Drops in production translated to significant reductions in cumulative milk value (-Can$287 to -Can$591; -US$228 to -US$470), MOFC (-Can$243 to -Can$540; -US$193 to -US$429), and gross profit (-Can$649 to -Can$908; -US$516 to -US$722) for mastitic cows at all stages. Differences between mastitic and healthy cows in the early lactation and transition stages remained for all variables in the 100-DIM analysis, but, aside from gross profit, were nonsignificant in the 305-DIM analysis. Gross profit accounted for all costs associated with mastitis and thus continued to be lower for mastitic cows at all stages, even in the 305-DIM analysis in which culled cows were omitted (-Can$485 to -Can$979; -US$386 to -US$779). The research reflects the performance implications of mastitis, providing more information upon which the producer can make informed culling decisions and maximize both herd profitability and cow longevity.

A calf-level study on colostrum management practices associated with adequate transfer of passive immunity in Québec dairy herds.

The objective of this study was to identify the calf-level colostrum management practices associated with an adequate transfer of passive immunity (TPI; defined as serum Brix refractance ≥8.4% in the first week of life) in small-sized herds. A total of 818 calves from 61 commercial Holstein dairy farms were included in this observational cross-sectional study. For each calf, sex, colostrum delivery method, colostrum volume fed at first meal, and time to first feeding (delay between birth and first colostrum meal) were noted. Blood and colostrum samples were collected to estimate the serum and colostrum quality using Brix refractometry. To quantify the level of bacterial contamination in colostrum samples, total bacteria count and total coliform count (TCC) were measured using the Petrifilm (3M, St. Paul, MN) culture system. In this study, 68% of calves had an adequate TPI (≥8.4%). For data distribution, the 25th, 50th, and 75th percentiles were 1.3, 2.8, and 3.3 L for the colostrum volume fed at the first meal; 20.9, 23.5, and 26.5% Brix; and 1.1, 3.1, and 6.5 h for the time to first feeding of colostrum, respectively. The odds of adequate TPI were 2.6 times higher in calves receiving ≥2.5 L colostrum at their first meal, 2.9 times higher in calves receiving colostrum with ≥24.5% Brix, and 1.6 times higher in calves receiving colostrum within 3 h after birth, than in calves not meeting these criteria. In the present study, median bacterial contamination distribution (interquartile range) in the first colostrum meal was 14,000 cfu/mL (3,000-83,000 cfu/mL) for total bacteria count, and 0 cfu/mL (0-1,000 cfu/mL) for TCC. Total bacteria count and TCC were not associated with the odds of adequate TPI in the final model. Overall, these results suggest that specific calf-level colostrum management practices are associated with adequate TPI in small- to medium-sized dairy herds.

A herd-level study on colostrum management factors associated with the prevalence of adequate transfer of passive immunity in Québec dairy herds.

The objective of this study was to identify herd-level colostrum management factors associated with the adequate transfer of passive immunity (TPI; defined as serum Brix refractance ≥8.4% in the first week of life). A total of 59 commercial Holstein dairy farms were included in this observational cross-sectional study. In every participating herd, a minimum of 14 Holstein calves were sampled to measure their TPI using a digital Brix refractometer. Colostrum samples fed to each of these calves were collected to estimate IgG concentration (colostrum quality) using a digital Brix refractometer and bacterial contamination using the Petrifilm (3M, St. Paul, MN) culture system. Dairy producers completed a questionnaire on colostrum management to assess on-farm practices. The study outcome was the prevalence of adequate TPI calculated based on the proportion of adequate TPI (defined with an individual threshold ≥8.4% Brix) on the total samples tested within each herd. According to the threshold determined in a previous study investigating the influencing colostrum management factors to achieve adequate TPI at the calf level, the prevalence of an adequate colostrum volume fed at first meal (≥2.5 L), the prevalence of adequate colostrum quality (≥24.5% Brix), the prevalence of an adequate time to first feeding (delay between birth and the first colostrum meal, ≤3 h), the prevalence of low aerobic bacterial contamination (≤20,000 cfu/mL), the prevalence of low coliform contamination (≤1,000 cfu/mL), and the prevalence of females were calculated. The herd-level prevalence of adequate TPI ranged from 24% to 100%, with a median of 68%. The median herd prevalences of an adequate colostrum volume fed at first meal, of adequate colostrum quality, of an adequate time to first feeding, of low aerobic bacterial contamination, of low coliform contamination, and of females, were 71, 42, 41, 64, 88, and 61%, respectively. In the final model, the prevalence of adequate TPI was associated with the prevalence of an adequate colostrum volume fed at first meal and the prevalence of an adequate time to first feeding. In summary, management practices varied greatly between farms and influenced the prevalence of adequate TPI.

Short communication: Efficacy of a second intrauterine cephapirin infusion for the treatment of purulent vaginal discharge and endometritis in postpartum dairy cows.

The objective of this study was to quantify the efficacy of a second intrauterine cephapirin treatment administered 14 d after the initial one on subsequent reproductive performance of postpartum dairy cows affected by purulent vaginal discharge (PVD) or endometritis (ENDO). In total, 4,140 Holstein cows from 30 commercial herds were enrolled in a randomized clinical trial. At 36 (±7) d in milk, cows were examined using the Metricheck device to diagnose PVD. An endometrial cytology sample was also collected from each cow to perform a leukocyte esterase test for diagnosing ENDO. Diagnosis of PVD and ENDO was done cow-side. Cows diagnosed with PVD or ENDO were assigned to receive 1 of 2 treatments: (1) a single intrauterine cephapirin infusion (500 mg of cephapirin benzathin; Metricure, Merck Animal Health, Kirkland, QC, Canada) at the time of initial examination or (2) a single intrauterine infusion at the time of initial examination and a second one 14 d later. Subsequent reproductive and culling events were collected until 200 d in milk. Statistical analyses were performed using univariable and multivariable mixed logistic regression models. In cows affected by PVD, a second intrauterine cephapirin infusion increased the pregnancy risk at first insemination in comparison with cows that only received one treatment (28.0 vs. 38.8%). In cows affected by ENDO, a second treatment also increased the pregnancy risk at first insemination compared with cows that only received one treatment (30.3 vs. 39.2%). Overall, these results demonstrate that administering a second intrauterine cephapirin infusion 14 d after the initial treatment in postpartum cows affected by PVD or ENDO did improve their subsequent reproductive performance.

Short communication: Diagnostic accuracy of the Petrifilm culture system for identifying colostrum with excessive bacterial contamination in Quebec dairy herds.

The objective of this study was to validate the diagnostic accuracy of the Petrifilm culture system (3M, St. Paul, MN) for identifying colostrum with excessive bacterial contamination. An observational cross-sectional study was conducted between October 2015 and February 2016. Two colostrum aliquots were collected during the first meal of 332 calves (33 commercial Holstein dairy farms) in Quebec, Canada. One aliquot per calf was used to quantify the total bacteria count and the total coliform count using standard bacteriological laboratory testing (reference test). These results were dichotomized to identify colostrum with excessive bacterial contamination [aerobic count plate (AC) >100,000 cfu/mL; coliform count plate (CC) >10,000 cfu/mL]. The Petrifilm system was used to quantify both aerobic and coliform contamination of the other colostrum aliquot from each calf. As such, AC and CC were used according to the manufacturer's recommendations. The area under the curve of the receiver operating characteristic curve of AC and CC compared with the laboratory were 0.83, and 0.95, respectively. Using the optimal threshold of >24,000 cfu/mL for AC results, the Petrifilm system had a sensitivity (Se) of 69%, specificity (Sp) of 86%, and a kappa value of 0.54. Using the optimal threshold of >4,000 cfu/mL for CC results, the Petrifilm system had a Se of 93%, Sp of 90%, and kappa value of 0.64. Overall, these results suggest that the Petrifilm system is an appropriate alternative for identifying colostrum with excessive bacterial contamination.

Randomized controlled trial of pegbovigrastim as an adjunct therapy for naturally occurring severe clinical mastitis cases in dairy cows.

The main objective of this study was to quantify the effect of pegbovigrastim (PEG) as an adjunct therapy for naturally occurring severe mastitis cases on survival, intramammary bacteriological cure, and subsequent milk production. A double-blinded, randomized controlled trial was conducted on a single commercial dairy farm. During the study period, all cows having a case of severe clinical mastitis, defined as the presence of abnormal milk and inflammation in one quarter or more combined with the presence of systemic signs (pyrexia, dehydration, or recumbency), were enrolled in the study. In addition to a standardized therapy combining systemic and intramammary antimicrobials as well as systemic anti-inflammatory drugs, cows received a subcutaneous injection of either 2.7 mL of 0.9% sterile saline (control group; CON) or 2.7 mL of PEG (PEG group). A milk sample for bacteriological analysis was taken before treatment was administered and a second sample was taken 14 d after enrollment. Survival (30 d post-treatment) and bacteriological cure (14 d post-treatment) were analyzed by survival analysis and chi-squared tests, respectively, whereas daily milk production was treated as a repeated measure in mixed regression models. The 77 cows enrolled in the study were of parity 2 to 4 (mean = 3) and between 3 and 302 d in milk (mean = 154). The bacteria identified in milk at enrollment were Klebsiella spp. (n = 48; 62%), Escherichia coli (n = 16; 21%), Enterobacter spp. (n = 10; 13%), or no growth (n = 3; 4%). The probability of survival during the first 30 d after treatment was higher in the PEG group (84%) than in the control group (46%). Daily milk production over the 30-d period following treatment and bacteriological cure 14 d post-treatment did not differ between groups. Overall, cows treated with PEG as an adjunct therapy for naturally occurring cases of severe clinical mastitis had a better survival than cows treated with saline.

Randomized controlled trial of reinsemination strategies in dairy cows diagnosed nonpregnant using color flow Doppler ultrasonography on d 21 after insemination.

The objective of this study was to quantify the reproductive performance of 4 reinsemination strategies in cows diagnosed nonpregnant using corpus luteum color flow Doppler ultrasonography on d 21 after last insemination. A total of 2,140 color flow Doppler ultrasonography exams from 845 Holstein cows from 10 commercial dairy herds were used in this study. Farms were visited every 2 wk by the research team. On d 7 after insemination, cows were enrolled in a randomized controlled trial to be assigned 1 of 4 treatments if they were subsequently diagnosed nonpregnant on d 21. All cows were then examined on d 21 using Doppler ultrasonography to diagnose nonpregnancy. Treatment A (CON) was the control group: nonpregnant cows were programmed to receive a standard Ovsynch protocol starting on d 32. Nonpregnant cows in treatment B (GnRH) were injected i.m. with GnRH on d 21 after insemination and reinseminated immediately. Cows in treatment C (2×GnRH) received an i.m. injection of GnRH on d 11 after insemination. If diagnosed nonpregnant on d 21 after insemination, they were injected i.m. with GnRH on d 21 after insemination and inseminated immediately. Cows in treatment D (Resynch) received an i.m. injection of GnRH on d 14 after insemination. If diagnosed nonpregnant on d 21 after insemination, they were injected i.m. with PGF2α on d 21 after insemination and injected i.m. with GnRH on d 24. Then, a standard Ovsynch protocol was started on d 32. Statistical analyses were performed using mixed logistic regression models accounting for cow clustering and herd effect. A theoretical simulation was performed for each treatment to quantify the proportion of cows remaining nonpregnant 42 d after initial insemination. Of the 2,140 color flow Doppler ultrasonography exams in the study, 870 (40.6%) had a Doppler score of D0 (n = 444) or D1 (n = 426), which were indicative of nonpregnancy and used for data analysis. Overall, the number of exams assigned to each treatment was as follows: CON = 223 (25.6%), GnRH = 214 (24.6%), 2×GnRH = 220 (25.3%), and Resynch = 213 (24.5%). The final mixed multivariable logistic regression model included treatment, parity, days in milk at enrollment, and herd. Conception risk at first insemination following enrollment was 31.4, 20.6, 31.9, and 48.7% for treatments CON, GnRH, 2×GnRH, and Resynch, respectively. Based on the simulation, if 100 cows were diagnosed nonpregnant at their color flow Doppler ultrasonography exam on d 21 after last insemination, the total number of cows remaining nonpregnant 42 d after the initial insemination would be 69, 72, 58, and 51 for treatments CON, GnRH, 2×GnRH, and Resynch, respectively. Thus, the treatments used in groups 2×GnRH and Resynch for cows diagnosed nonpregnant on d 21 after insemination yielded better results than those used in the other groups.

Communication preferences and social media engagement among Canadian dairy producers.

The objective of this study was to determine communication preferences of dairy producers in Canada. A secondary objective was to evaluate social media engagement of dairy producers. A survey was administered to Canadian dairy producers between March and April, 2015 to collect information on current management practices on their farms. A total of 1,373 Canadian dairy producers responded to the survey, representing a response rate of 12%. The survey consisted of 192 questions; however, only questions regarding producer demographics, importance of information sources, and internet and social media use were evaluated in this study. The primary outcome variables of interest included use of the internet to access dairy information, importance of different sources of information about dairy herd health and management, and use of online search engines and social media platforms. For each outcome, logistic regression analyses were used to investigate associations between the outcome and demographic variables. Veterinarians were viewed as a "very important" source of information by the majority of respondents (79%), whereas milk recording and dairy producer organizations were viewed as a "very important" source of information by 36% of respondents. Other producers (46%) and magazines or newspapers (51%) were commonly viewed as an "important" source of information. Online search engines were commonly used by respondents (94%). Social media was viewed as less important, and had mixed levels of use. YouTube (70%), Facebook (63%), and Twitter (18%) were the most commonly used social media platforms. Eighty percent of Twitter users reported using the platform to interact with and obtain or share information about herd health management online, which was the highest reported interactivy regarding herd health among all social media platforms. This exploratory study offers insight into the communication preferences of Canadian dairy producers and can be used to facilitate future communication strategies aimed at engaging rural farming audiences across Canada.

Short communication: Accuracy of estimation of lameness, injury, and cleanliness prevalence by dairy farmers and veterinarians.

Lameness, injuries, and cleanliness are considered important indicators of dairy cow welfare, milk production, and milk quality. Previous research has identified that farmers globally underestimate the prevalence of these cow-based measurements, but no information on the perceptions of veterinarians is available. Because veterinarians are often perceived as the main providers of health advice on farms, the objective of the present study was to evaluate the relationship between the true prevalence of lameness, injury (hock, knee, neck), and cleanliness (udder, legs, flanks), and the estimated prevalence of these issues by farmers and their herd veterinarians. A cross-sectional study was conducted between February 2016 and July 2017. First, the farm owner and the herd veterinarian were asked to estimate the prevalence of lameness, of neck, knee and hock injuries, and of udder, leg, and flank cleanliness on the farm. The research team then visited the farm and scored all lactating cows in the herd for each measurement. Linear regression models were used to assess the relationship between the prevalence estimated by the veterinarians and the farmers, of each cow-based measurement, and the true prevalence on the farm. The 93 herds enrolled had a median of 55 milking cows and were housed in tiestall (90%) and freestall (10%) barns. Ten herd veterinarians participated and were involved with 2 to 22 enrolled farms each. A wide variation was detected in the true prevalence of the different cow-based measurements among herds (lameness: range = 19-72%, median = 36%; neck injuries: range = 0-65%, median = 14%; knee injuries: range = 0-44%, median = 12%; hock injuries: range = 0-57%, median = 25%; dirty udder: range = 0-55%, median 13%; dirty legs: range = 0-91%, median = 18%; and dirty flanks: range = 0-82%, median = 20%). For both veterinarians and farmers, the perception of each cow-based measurement prevalence increased incrementally as the herd's true prevalence increased. Overall, farmers and veterinarians underestimated cow-based measurements. Farmers and veterinarians more accurately estimated lameness prevalence in herds with higher prevalence than in herds with low prevalence, suggesting a better awareness of the issue on farms with lameness problems. Injuries were less accurately estimated in herds with higher injury prevalence compared with herds with lower prevalence, suggesting an opportunity for better knowledge transfer in this area.

Short communication: Describing mortality and euthanasia practices on Canadian dairy farms.

The objective of this study was to describe mortality rates and euthanasia practices used for cows, heifer calves, and male dairy calves on Canadian dairy farms. An internet survey was administered to Canadian dairy producers between March and April 2015 to collect information on current management practices. Approximately 81% (867/1,076) and 63% (673/1,065) of respondents reported that at least one animal died unassisted and at least one animal was euthanized on the farm in the preceding 12-mo period, respectively. Overall, mean mortality was 8% for cows, and 6 and 2% for preweaning and weaned heifers, respectively. On average, 48, 76, and 89% of all reported mortality events in cows, weaned heifers, and preweaning heifers were recorded as unassisted deaths. Cows that died without assistance were necropsied more often than preweaning heifers dying without assistance; these cows were also necropsied more than cows that were euthanized. Conversely, preweaning heifers that were euthanized were necropsied more frequently than those that died without assistance. Choosing not to perform necropsies on animals that die of unknown causes could represent a missed opportunity to identify cause of death and inform changes to prevent future deaths. The use of a firearm was the most common method for euthanizing cows and heifers (54%) and male dairy calves (51%). Approximately 7% of respondents reported using blunt force to euthanize animals. The use of this method was much higher for euthanasia of male dairy calves (34%) than for heifer calves (7%). Québec respondents euthanized their animals using blunt force more often than farmers from other regions. Further, 53% of respondents using blunt force indicated it was their primary method of calf euthanasia; these results are extremely concerning. Approximately 31% of respondents who reported that they do not use blunt force to euthanize heifers and cows did report using blunt force to euthanize male dairy calves. These results can be used to inform veterinarian-client communication, broader extension tools and programs, and industry policies to improve dairy cattle health and welfare, a goal that is becoming of increasing importance from a consumer assurance perspective.

Canadian National Dairy Study: Describing Canadian dairy producer practices and perceptions surrounding cull cow management.

Farmer decisions surrounding culling have an important effect on the health and welfare of cull cows. The objectives of this study were to describe the self-reported shipment behaviors of Canadian dairy producers and understand farmer perspectives on the factors that were most influential in their decision to cull a cow. A nationwide survey was administered between March and April 2015 that included 192 questions covering producer background information, farm characteristics, biosecurity practices, disease prevalence, calf health, cow welfare, lameness, milking hygiene, reproduction, and Internet and social media use. The survey yielded a 12% response rate; a total of 1,076 respondents (78% of all survey respondents completed the culling section of the survey) were included in this study for analysis. Approximately 80, 51, and 38% of respondents reported shipping at least 1 cow to auction, direct to slaughter, and to another dairy farm in the past 12 mo, respectively. Ability of the cow to remain standing (93% of respondents) and drug withdrawal times (92% of respondents) were identified as the most important factors for consideration when culling cows. The time between culling decision and when the cow was actually transported was longer for lame cows than sick cows; almost 70% of respondents reported that cows culled for illness were typically shipped within 1 wk of culling decision, whereas only 51% of respondents indicated the same was true for lame cows. Last, Canadian dairy producers generally exhibited strong confidence that their culled cows would arrive at slaughter in the same condition as they left, but felt very unsure about knowing the location of their final destination. These results highlight several gaps between producer perceptions and the true situation, and can be used to develop tailored programs and inform policy and regulatory decisions aimed at improving cull cow decisions and cow welfare.

Neutrophil-to-lymphocyte ratio (NLR) distribution shows an advantage compared to C-reactive protein (CRP) for the early inflammation monitoring after total hip arthroplasty.

C-reactive protein (CRP) distribution has been used to monitor early inflammation after total hip arthroplasty (THA). Neutrophil to lymphocyte ratio (NLR) is a new and cheap inflammatory marker. This study aimed to verify whether Neutrophil to lymphocyte ratio (NLR) distribution has an advantage when compared to C-reactive protein (CRP) distribution for the inflammation monitoring after total hip arthroplasty (THA). 116 THA patients were retrospectively selected over a 2 years period. They all had available blood tests preoperatively and at postoperative days 2, 4 and 42. Median peak values were compared between CRP and NLR. The effect of demographics on CRP and NLR was tested. At days 4 and 42, 100% and 16.3% of patients had not reached normal CRP (< 10mg/L) while 56.8% and 6.8% of patients had not reached normal NLR (<5) respectively. There was no effect of demographics on NLR except for age. Older patients had higher NLR (p 0.037). NLR showed a quicker return to normal than CRP. Our results show that NLR seems to be a better marker to follow inflammation after THA than CRP.

Short communication: Accuracy of corpus luteum color flow Doppler ultrasonography to diagnose nonpregnancy in dairy cows on day 21 after insemination.

The main objective of this study was to determine the accuracy of corpus luteum color flow Doppler ultrasonography (CLCFDU) to diagnose nonpregnant dairy cows 21 d after insemination. A secondary objective was to determine the accuracy of other indirect tests such as corpus luteum size and progesteronemia. Data from 1,632 Holstein cows (10 commercial herds) were used for the analysis in this prospective cohort study. The herds were visited weekly by a veterinarian and an animal health technician. During farm visits, cows were examined on d 21 after insemination using transrectal B-mode ultrasonography to quantify the presence and size of the corpus luteum. After identification of the corpus luteum, CLCFDU was performed and scored as D0, D1, D2, or D3 when 10% or less, between 11 and 30%, between 31 and 60%, or 61% or more of the corpus luteum surface was colored, respectively. A blood sample from coccygeal vessels was also collected to quantify progesteronemia. Farmers were blinded to these findings and no intervention was performed following examination. On d 32 after insemination, the cows were examined by the regular herd veterinarian using transrectal palpation and B-mode ultrasonography to determine whether the cows were pregnant or not (the reference test). Statistical analyses were conducted using 2 × 2 contingency tables. The apparent prevalence, sensitivity, specificity, positive predictive value, and negative predictive value of CLCFDU for predicting nonpregnancy were 22.0, 36.6, 99.0, 98.1, and 52.0%, respectively, when using D0 only as the diagnostic criterion; they were 47.2, 76.4, 94.8, 93.5, and 73.8%, respectively, for D0+D1 criteria. The same measures for cows with a corpus luteum <15 mm were 8.0, 11.7, 97.5, 86.9, and 43.4%, respectively, and they were 51.9, 67.4, 70.4, 76.6, and 60.0%, respectively, for progesteronemia <1 ng/mL. The measures of accuracy of CLCFDU to identify nonpregnant cows on d 21 after insemination were high, and the apparent prevalence varied depending on the diagnostic criteria used. The measures of accuracy of corpus luteum size (<15 mm) for the same purpose were high; however, apparent prevalence was low. The measures of accuracy of progesteronemia (<1 ng/mL) were low. In conclusion, CLCFDU had excellent accuracy to diagnose nonpregnancy in dairy cows on d 21 after insemination.