Assessing the utility of leukocyte differential cell counts for predicting mortality risk in neonatal Holstein calves upon arrival and 72 hours postarrival at calf rearing facilities

Abstract

There is growing concern about the level of antimicrobial use and antimicrobial resistance in food producing animals. An area of opportunity to reduce antimicrobial use could be in the treatment of young calves during the first week following arrival at calf rearing facilities. Group metaphylaxis is common due to the unknown age and history of calves that undergo several stressful events prior to arrival, such as transportation, co-mingling and variable periods of fasting. It may be possible to reduce antimicrobial use at this stage in the production cycle without sacrificing animal health and welfare if the calves at highest risk of morbidity and mortality could be identified and treated in a highly selective manner. Recent studies have identified indicators of future risk for morbidity and mortality that can be measured at arrival such as biomarkers and physical exam factors. Bovine haematology, when used in conjunction with clinical examination findings, could be used to improve disease diagnosis. The objective of this study was to assess the utility of leukocyte differential cell counts taken at the time of arrival at a calf rearing facility and 72 hours post arrival for determining mortality risk during the production cycle.