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UBC Theses and Dissertations

Benchmarking passive transfer of immunity and growth in dairy calves Atkinson, Dax


Poor health and growth of young dairy calves can have lasting effects on development and future production. This study aimed to benchmark calf-rearing outcomes in a cohort of Canadian dairy farms, report these findings back to producers alongside their veterinarians, and document the results. A total of 18 Holstein dairy farms, located in the Fraser Valley region of British Columbia, were recruited and surveyed on current colostrum and feed management practices of pre-weaned calves. Blood samples were collected from 1 to 7 day old calves to estimate serum total protein levels by digital refractometry. Failure of passive transfer (FPT) was determined using a total protein threshold of 5.2 g/dL. Average daily gains (ADG) were estimated from 1 to 70 day old pre-weaned heifers using heart-girth tape measurements with early (≤ 35 days) and late (> 35 days) period growth also analysed separately. At first assessment, the average farm FPT rate was 16%. Overall ADG was 0.68 kg/day, with early and late period growth rates of 0.50 and 0.86 kg/day, respectively. Following delivery of benchmark reports, all participants volunteered to undergo a second assessment. The majority (83%) of participants elected to make at least one colostrum or feed protocol change between data collection periods, including increased colostrum at first feeding, increased initial and maximum daily milk, and reduced time to first colostrum. Farms that made such changes experienced improved outcomes; average FPT rates were reduced by 9% and ADG was increased by 0.06 kg/day for all calves, and by 0.16 kg/day for calves less than 36 days old. These results indicate that benchmarking FPT and ADG can motivate producer engagement on calf care, leading to improved production and welfare outcomes for calves on farms that apply relevant management changes.

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