Impact of 3 colostrum replacement strategies on immunoglobulin G absorption efficiency, passive immunity, health, and growth in beef calves.

Abstract

OBJECTIVE: The study objectives were to calculate the apparent efficiency of immunoglobulin G (IgG) absorption in beef calves receiving complete colostrum replacement and to compare the effects of 3 colostrum replacement strategies on the apparent efficiency of IgG absorption (AEA), transfer of passive immunity (TPI), morbidity, mortality, and average daily gain (ADG). METHODS: 45 newborn beef calves were randomly assigned to 1 of 3 colostrum interventions. Group A received approximately 170 g of IgG via colostrum replacer after birth. Group B received approximately 250 g of IgG in 2 feedings within 6 to 8 hours. Group C received approximately 250 g of IgG in 3 feedings within 12 to 14 hours. Serum IgG concentrations were determined at 0, 6, 12, and 24 hours. Transfer of passive immunity, AEA, and ADG were compared among intervention groups. Transfer of passive immunity, morbidity, mortality, and ADG were also compared to 15 control calves left with their dams for natural nursing. RESULTS: Median AEA for groups A, B, and C at approximately 24 hours was 36.2%, 26.3%, and 23.9%, respectively, with no significant differences among groups when accounting for other covariates. Average serum IgG concentration and the proportion of calves with failed TPI (IgG < 10 g/L) and adequate TPI (IgG &#x2265; 24 g/L) was not statistically different among intervention and control groups. Morbidity, mortality, and ADG until weaning was similar among all groups. CONCLUSIONS: AEA in beef calves was lower than that reported in dairy calves. All colostrum replacement strategies prevented failed TPI. There was no difference in health and growth outcomes between intervention and control groups. CLINICAL RELEVANCE: While timely feeding of &#x2265; 170 g of IgG prevented failed TPI in beef calves, &#x2265; 250 g of IgG may be necessary to achieve adequate TPI. Producers and veterinarians should not hesitate to intervene to ensure timely colostrum ingestion.