CASE STUDY: Effects of timing of a modified-live respiratory viral vaccination on performance, feed intake, antibody titer response, and febrile response of beef heifers12

The objective of this study was to evaluate the effects of timing associated with the administration of a modified-live respiratory viral vaccine (bovine herpes virus-1, bovine viral diarrhea virus, bovine parainfluenza-3, bovine respiratory syncytial virus) on d 0 or on d 14 of a receiving period on performance, feed intake, antibody titer response, and the febrile response in beef heifers. Our hypothesis was that vaccine timing will alter the febrile response and feed intake of feeder cattle. Thirty-six heifers (Angus and Angus crosses; initial BW = 265 ± 20 kg) were ranked by BW and assigned to treatment pens (9 pens total) in a completely randomized design. Treatments (3 pens/treatment with 4 heifers/pen) included no vaccine (CON), vaccination on d 0 (DO), and a delayed vaccination on d 14 (D14) of the receiving period. Heifers were fed in 6 × 12 m pens equipped with GrowSafe feeding systems. Daily feed intakes were recorded and BW measured on d − 1, 0, 14, 27, and 28. Temperature data loggers were attached to blank controlled intrauterine drug-release devices (CIDR; contained no active compound) that recorded vaginal temperatures every 5 min for the experiment; vaginal temperatures were then averaged for every hour before data analysis. All data were analyzed using pen as the experimental unit. No differences (P > 0.10) among treatments were observed for initial BW, final BW, ADG for d 0 to end, or overall G:F. A treatment × day interaction (P < 0.05) was observed for feed intake. Daily intake was decreased for D14 versus D0 on d 14 (P < 0.01) and 15 (P < 0.10) and decreased (P < 0.05) on d 15 for the average of vaccinated calves versus CON. Eating rate (grams consumed/eating duration) was decreased (P < 0.05) on d 14 for D14 versus D0. No differences (P > 0.10) among treatments were noted in the number of eating events per day. A treatment × day interaction (P < 0.01) was observed for vaginal temperature. Vaginal temperature was increased (P < 0.10) on d 1 for D0 versus D14 heifers and increased for D14 versus D0 on d 14 (P < 0.01), 15 (P < 0.05), and 16 (P < 0.05). Our results suggest that time of administration of a modified-live respiratory viral vaccine can alter feed intake and vaginal temperature in feeder heifers.