Serum total protein concentrations in surplus dairy calves in British Columbia

Objective This cross-sectional study aimed to evaluate serum total protein (STP) concentrations in surplus calves in British Columbia and explore associated factors including calf breed, sex, hydration, month of sampling, and frequency of calf pickup. Animal Neonatal dairy and dairy-beef crossbred calves recently purchased from dairy farms and transported to an assembly facility. Procedure Calves included in this study (N = 1449) were assessed at an assembly facility from March to August 2021, and blood samples were collected to measure STP as an indicator of transfer of passive immunity (TPI). Associations between STP and calf characteristics (breed, sex, hydration), month of sampling, and how frequently calves were collected from the source dairy farms (daily versus twice weekly or less) were evaluated with a linear regression model including farm as a random effect. Results Of the 1433 serum samples, 24% had STP concentrations that were "poor:" defined as, 5.1 g/dL, and the proportion with poor STP varied widely among farms. Dairy-beef crossbred calves and calves that were dehydrated had higher STP concentrations, whereas those sampled in July had lower STP. This study was limited to calves purchased by 1 calf buyer but represented a large number of calves from 12% of the dairy farms in British Columbia. Conclusion Approximately 1/4 of surplus dairy calves had poor STP concentrations. Clinical relevance Ensuring surplus dairy calves have successful TPI is an important opportunity to bolster their health and welfare.