Altering the time of vaccination against respiratory pathogens to enhance vaccine efficacy, health, and performance of feedlot cattle

Abstract Text: Ninety Angus × Hereford calves were ranked by gender, BW, and age, and assigned to 1 of 3 vaccination schemes against respiratory pathogens: 1) vaccination at weaning (d 0) and at feedlot entry (d 30; CON, n = 30), 2) vaccination 15 d before weaning (d -15) and 15 d before feedlot entry (d 15; EARLY, n = 30), and 3) vaccination 15 d after weaning (d 15) and 15 d after feedlot entry (d 45; DELAYED, n = 30). From d -15 to 6, calves were maintained on pasture. On d 7, calves were placed according to treatments into 1 of 18 drylot pens (6 pens/treatment; 5 calves/pen), and fed a forage-based preconditioning diet. On d 30, calves were transported 1,440 km in a livestock trailer and returned to different drylot pens for a 45-d receiving period. Calves were fed a forage + concentrate diet during the receiving period. Blood samples and BW were collected on d -15, 0, 15, 30, 45, 60, and 75. Additional BW was collected on the day after blood sampling so 2 consecutive BW were recorded and averaged. There were no treatment effects on BW pre-weaning, weaning, or during the preconditioning and receiving periods (P ≥ 0.59). The EARLY calves had less (P ≤ 0.05) ADG pre-weaning, however had greater (P ≤ 0.04) ADG during feedlot receiving compared to the other treatments. During preconditioning, CON had greater (P = 0.05) DMI compared with EARLY and DELAYED calves, but there were treatment effects (P ≥ 0.20) on DMI during the feedlot receiving. There were no treatment effects (P ≥ 0.16) on G:F, morbidity, or mortality. By 15-d after initial vaccination, DELAYED calves had the greatest (P < 0.01) antibody titers against Mannheimia haemolytica, and EARLY calves had the lowest (P ≤ 0.05) antibody titer against this pathogen. By revaccination, there was no difference (P = 0.82) between DELAYED or CON for antibody titers against M. haemolytica titers, while EARLY titers remained the lowest (P < 0.01). However, by 45-d after initial vaccination, EARLY calves had the greatest antibody titers (P ≤ 0.05) against M. haemolytica, which remained the greatest until 60-d after initial vaccination. These data suggest that while pre-weaning ADG may be inhibited by vaccination before weaning, vaccination before weaning and revaccination before feedlot receiving can improve overall antibody titer to M. haemolyticaand ADG during feedlot receiving.

Keywords: feeder cattle, health, performance, vaccination