Kristen Y. Edwards

The objective of this retrospective cohort study was to explore factors associated with neonatal calf diarrhea (NCD), bovine respiratory disease (BRD), lung consolidation (LC), and mortality on Ontario dairy farms. Health records from 2,349 Holstein calves from birth until 56 d of age across 9 dairy farms were analyzed using multivariable mixed-effects logistic regression models, which accounted for farm-level clustering through a random effect. The models evaluated associations between the outcomes of interest and season of birth, birth BW, calving ease, first colostrum feeding volume, colostrum quality (measured as Brix percentage), number of colostrum feedings, time of birth, and transfer of passive immunity (TPI), using the categories of poor (<5.1 g/dL), fair (5.1-5.7 g/dL), good (5.8-6.1 g/dL), and excellent (≥6.2 g/dL). Season of birth was the only variable associated with NCD (23% incidence), with calves born in the summer having higher odds of NCD (odds ratio [OR] = 1.54; 95% CI: 1.08-2.20) than those born in the winter. For BRD (48% incidence), calves born in the fall had higher odds of BRD (OR = 1.51; 95% CI: 1.12-2.04) compared with winter-born calves, whereas calves born in the summer had lower odds (OR = 0.67; 95% CI: 0.51-0.88). Additionally, calves with excellent TPI had lower odds of BRD compared with those with poor TPI (OR = 0.71; 95% CI: 0.52-0.98). The odds of LC (51% incidence) were lower in calves with good (OR = 0.56; 95% CI: 0.38-0.82) or excellent (OR = 0.41; 95% CI: 0.28-0.61) TPI compared with poor TPI. Summer-born calves also had lower odds of LC than winter-born calves (OR = 0.72; 95% CI: 0.51-1.00). Finally, each 1-kg increase in birth weight was associated with reduced odds of LC (OR = 0.96; 95% CI: 0.94-0.98). For mortality (3% incidence), calves born in the fall had lower odds (OR = 0.23; 95% CI: 0.05-0.97) of death compared with those born in the winter. Similarly, calves with good (OR = 0.13; 95% CI: 0.07-0.78) or excellent (OR = 0.34; 95% CI: 0.12-1.00) TPI status had reduced odds of mortality compared with those with poor TPI. In contrast, the odds of mortality were higher for calves with a health event compared with those with no health events (OR = 20.18; 95% CI: 4.24-96.13) and for calves with LC compared with those without LC (OR = 2.65; 95% CI: 1.02-6.88). These results identify some modifiable factors associated with preweaning calf health and survival and highlight the importance of improving colostrum management and early disease detection, as well as the influence of season.

The objective of this narrative review is to provide a systematic framework for veterinarians to investigate dairy calf health, focusing on critical control points and key performance indicators (KPIs) to address morbidity and mortality challenges in preweaned calves. Recommendations target prenatal maternal nutrition, heat stress abatement, and optimal calving management to minimize risks associated with perinatal mortality and preweaning morbidity. Further, comprehensive colostrum management is discussed to ensure excellent transfer of passive immunity, which includes prompt collection and feeding within two hours of birth at a volume of 8.5–10% of calf body weight. Nutritional guidance emphasizes the importance of transition milk and feeding higher planes of nutrition to support immunity, with recommendations that milk total solids exceed 10% to meet energy needs. Environmental management recommendations include a minimum of 3.3 m² of space per calf, the use of low-dust bedding, and air quality controls to reduce respiratory disease. Lastly, regular health data collection and KPI monitoring, such as average daily gain and morbidity rates, are essential for data-driven improvements. By implementing these evidence-based recommendations, veterinarians can support dairy farmers in reducing calf morbidity and mortality, ultimately enhancing calf welfare and lifetime productivity.

The objective of this randomized controlled trial was to evaluate the efficacy of supplementing bovine colostrum replacer during weaning to reduce intestinal permeability and improve gain. For this experiment, 65 calves were enrolled and housed individually until 70 d of age. Calves were fed milk replacer (150 g/L) 3 times daily with 9 L/d, 10.5 L/d, 11.25 L/d, and 12 L/d offered from d 1-7, d 8-14, d 15-21, d 22-56, respectively. Calves were weaned over 8 d from d 57-64, receiving a total of 7.8 L in 2 meals/d from d 57-60 and 3.8 L/d in one feeding from d 61-64. At d 57, calves were blocked by birth weight and randomly assigned to one of 2 treatments, equal in metabolizable energy, which were fed once daily during weaning from d 57-64: control (CON; n = 31 calves): 3.8 L milk replacer (150 g/L) fed by nipple bottle, or colostrum supplementation (COL; n = 34): a mixture of 1 L bovine colostrum replacer (125 g/L) and 3 L milk replacer (150 g/L) with 3.8 L of the mixture fed by nipple bottle. Serum IgG was measured within 48 h of birth and body weight was taken at d 0, 57, 60, 64, 70, 77, and 84. Starter intake and bovine respiratory disease (BRD) score were measured daily from d 50-70 and fecal consistency was examined daily from d 56-70. Serum β-hydroxybutyrate (BHB) and lung consolidation were evaluated at d 57, 64, and 70 and intestinal permeability was assessed by recovery of chromium-EDTA, lactulose, and d-mannitol from plasma after oral administration at d 56 and 65. There was no difference in body weight between treatment groups at the start of weaning, but COL were 2.79 kg (95% CI: 0.90-4.68) and 2.76 kg (95% CI: 0.86-4.65) heavier than CON at d 77 and 84, respectively. Additionally, COL tended to gain 100.00 g/d more than CON calves (95% CI: -10.41-207.13) from d 57-84. There were no differences in any of the other variables measured. Supplementation of bovine colostrum replacer during weaning may improve weight gain, but the mechanism of action is not clear.

Establishing accurate illness and treatment rates in dairy calves is crucial, yet calf health records are often incomplete. Thus, the objective of this study was to investigate barriers for dairy farmers for recording calf illnesses and treatments on dairy farms in Ontario, Canada. An online survey was completed by a convenience sample of 88 Ontario dairy farms in 2022, with 34 questions regarding farm demographics, current practices surrounding record keeping and analysis, and factors that would improve recording compliance. Multivariable models were built to assess associations between explanatory variables and the following outcomes: likelihood of making management or treatment protocol changes based on records analysis, factors that would increase the use of electronic recording methods, and whether all calf illnesses and treatments are recorded. Pearson's chi-squared tests were also used to investigate associations between explanatory variables and whether the respondent agreed or disagreed with a proposed reason for why a calf illness or treatment would not be recorded on their farm. Producers had 3.45 times greater odds of recording all antimicrobial treatments if they used a computer software system compared with those that did not. With respect to anti-inflammatory treatments, producers had 3.11 times greater odds of recording these treatments if records were located in the calf barn than elsewhere. Nonfamily employees had 6.08 times greater odds of recording all supportive therapy treatments than farm owners. When calf health records were kept in the calf barn, respondents were less likely to report that illnesses were not recorded due to time constraints (5% vs. 36% if records were elsewhere) or because calf health records were not analyzed (10% vs. 34% if records were elsewhere). On farms that recorded calf treatments in a paper booklet, respondents were more likely to report that treatments were not recorded because calf health records were not analyzed (44% for paper records vs. 21% for other systems). The most commonly indicated factors that would increase recording of illness were recording with a mobile app (27% of respondents) and for the recording system to be easy to use (31% of respondents). Overall, these data indicate that recording may be improved by keeping calf health records in close proximity to the calves and using a recording method that allows for data analysis. An easy-to-use mobile app may also improve recording if it could be used in the calf barn, provide data analytics, and allow for time-efficient data entry.