Monitoring bovine dairy calf health and related risk factors in the first three months of rearing

Abstract

Abstract Background Rearing replacement heifers is pivotal for the dairy industry and is also associated with high input costs for the preweaned calves, due to their higher susceptibility to diseases. Ensuring calf health and viability calls for systematic approaches in order to mitigate the costs induced by managing sick calves and to ensure animal welfare. The objective of this study was to develop a systematic and feasible health-monitoring tool for bovine dairy calves based on repeated clinical observations and diagnostic results of calves at three time points; the first (T0), the third (T1) and the 12th (T3) week of age. The study included observations from 77 dairy heifer calves in nine Danish commercial dairy herds. Clinical scoring included gastrointestinal disease (GD) and respiratory disease (RD). The average daily weight gain (ADWG) was estimated from heart-girth measurements. Pathogen detection from nasal swabs and faecal samples were analysed for 16 respiratory and enteric pathogens by means of high-throughput rt-PCR. Immunisation status was assessed by serum Brix% at T0. All measures obtained in each herd were visualised in a panel to follow the health status of each calf over time. Results: The individual clinical observations combined with diagnostic information from immunisation and pathogen detection form each enrolled calf are presented in a herd dashboard illustrating the health status over the study period. This monitoring revealed failure of passive transfer (Brix%<8.1) in 31% of the 77 enrolled calves, signs of severe GD peaked at T0 with 20% affected calves, while signs of severe RD peaked at T2 with 42% affected calves. ADWG over the first eight weeks was estimated to be 760 g (± 190 g). Pathogen profiles varied between herds. Conclusions: Combining the different sources of information in one visualisation panel allows calf caretakers to detect emerging infections and initiate timely interventions as well as to evaluate the effect of given interventions. It can also provide quality assurance of calf rearing and management practices.