Predictors of diarrhea, mortality, and weight gain in male dairy calves.

Discipline: calf rearing; Keywords: dairy calf, health status, scouring
Young dairy calves are vulnerable to disease, with calf mortality being highest during the first few weeks of life. Diarrhoea is one of the primary causes. Calves with diarrhoea experience dehydration, decreased appetite, and difficulty standing. Calves that survive an initial bout of diarrhoea usually show reduced weight gain. It is also an animal welfare issue and should therefore be prevented as far as possible. Prevention includes good observation and detection of faecal consistency. One method to improve the consistency and repeatability of diarrhoea detection is to use faecal consistency scoring, where observers visually assess faeces and categorize them as being either normal, semi-solid, loose, or watery. Abnormal consistency, however, has not been well-studied. Hence, the primary objective of the study by Dr M. Schinwald and colleagues was to determine the effect of an abnormal faecal consistency score on weight gain and mortality in male Holstein calves and to identify risk factors associated with the occurrence of an abnormal faecal consistency score. Their results were published in the Journal of Dairy Science, Volume 105 of 2022, page 5296 to 5309, the title of the paper being: Predictors of diarrhea, mortality, and weight gain in male dairy calves.

The study used 2616 calves entering a calf-rearing facility for veal calves in Canada. The results nevertheless are considered relevant to rearing of heifer calves on farm. Faecal consistency scores were assigned twice daily for the first 28 days following arrival, where a score of 2, indicating runny consistency, and 3, indicating watery consistency, were classified as diarrhoea. Severe diarrhoea was classified by a score of 3. Serum total protein was measured upon arrival and the source of the calf (i.e., whether the calf came from a calf seller, local farm, or auction) was recorded. Body weight measurements were also collected at arrival and at 14, 56 and 77 days after arrival. Calf mortality and disease treatment during the first 77 days were recorded.

On average, calves had diarrhoea for 16% (4.51 days) of the first 28 days under observation, and severe diarrhoea for 7% (1.87 days) of the 28 days under observation. The proportion of days with diarrhoea significantly decreased weight gain at 14, 56 and 77 days following arrival. An increased proportion of days with diarrhoea increased the risk of mortality. The results also showed that a higher proportion of days with an abnormal faecal score increased the hazard of antibiotic treatment. With respect to factors associated with the occurrence of abnormal faecal consistency, it was found that arrival weight and the source of calves were significant predictors. Specifically, for every additional kilogram of body weight at arrival, the proportion of days with diarrhoea decreased by 7%. With respect to source, calves from calf sellers had a higher proportion of days with diarrhoea compared with those sourced directly from local dairy farms.

The results highlight the substantial influence the presence of abnormal faecal consistency has on short-term weight gain, mortality risk, and morbidity risk. It was also demonstrated that diarrhoea occurrence can be predicted using body weight at arrival and calf source.