Effects of respiratory vaccination timing and growth-promoting implant on health, performance, and immunity of high-risk, newly received stocker cattle1

This experiment was conducted to determine the effects of pentavalent respiratory vaccination timing with or without a hormonal growth implant on arrival (d 0) on health, performance, complete blood count, and vaccine response in high-risk, newly received stocker calves during a 42-d receiving period. Bull and steer calves (n = 384) were weighed (initial BW = 202 ± 4.1 kg), stratified by castrate status on arrival, and assigned randomly to 1 of 4 treatments arranged in a 2 × 2 factorial: 1) arrival (d 0) vaccination, with implant, 2) arrival vaccination, without implant, 3) delayed (d 14) vaccination, with implant, and 4) delayed vaccination, without implant. The proportion of calves treated for bovine respiratory disease and days to initial bovine-respiratory-disease treatment did not differ (P ≥ 0.12) among treatments. Overall ADG (d 0 to 42) did not differ because of vaccination timing (P = 0.53) or implant (P = 0.64). Bovine viral diarrhea virus type 1a antibody concentrations were greater (P = 0.02) for calves vaccinated on arrival and increased (P = 0.01) over time following vaccination. Results indicate a growth promoting growth implant administered on arrival to high-risk stocker calves did not increase ADG. Morbidity rate was high (> 80% first pull rate) but was not affected by vaccine timing or implant. Vaccination on arrival increased bovine viral diarrhea virus type 1a antibody concentrations compared with the delayed procedure.