The Effect of bovine respiratory syncytial virus vaccination on health, feedlot performance and carcass characteristics of feeder cattle

Abstract

A 2-year study was conducted in 2001-2003 to determine the effects of a feedlot-arrival modified-live viral vaccination protocol containing adjuvanted bovine respiratory syncytial virus (BRSV) compared to a vaccination protocol not including adjuvanted BRSV on health, feedlot performance and carcass characteristics of feeder cattle. The vaccine products compared were a multivalent adjuvanted modified-live bovine rhinotracheitis virus, bovine diarrhoea virus, bovine parainfluenza-3 virus, respiratory syncytial virus vaccine (4-WAY) and a multivalent adjuvanted vaccine of similar formulation which did not contain BRSV (3-WAY). A total of 50 blocks, evenly divided between steers and heifers, were allocated to the study involving 19?099 cattle. Yearling feeder cattle were primarily used, with 161 average days on feed. Interactions were not observed between vaccine treatment and feedlot location, placement season, animal sex or animal age. Percent of overall morbidity due to respiratory disease was less (P=0.0629) for cattle vaccinated with 4-WAY vaccine compared to 3-WAY. Overall mortality, expressed as the number of animals per pen that died (P=0.0020) and percent deaths per pen (P=0.0007), was improved for cattle vaccinated with 4-WAY versus 3-WAY vaccine. The number of animals per pen that died due to respiratory disease was less (P=0.0060) for 4-WAY compared to 3-WAY. Overall case fatality, expressed as the number of treated animals per pen that died (P=0.0116) and percent of treated animals that died (P=0.1027), was improved for cattle vaccinated with 4-WAY vs. 3-WAY vaccine. The number of animals treated for respiratory disease per pen that died was less (P=0.0132) in the 4-WAY group compared to 3-WAY. Medical treatment cost per animal treated was $2.01 per head less (P=0.0688) for cattle vaccinated with 4-WAY. All other health parameters measured were similar between the two vaccine treatments. Feedlot performance variables such as dry matter feed intake, average daily liveweight gain and feed conversion were not different between the two vaccine treatments. The majority of carcass characteristics measured were similar for the two vaccine treatments; however, the percent Yield Grade 2 carcasses were less (P=0.0501) and the percent Yield Grade 3 carcasses greater (P=0.0561) for cattle vaccinated with 4-WAY compared to 3-WAY. Net feedlot margin was numerically increased $4.33 per head for cattle vaccinated with 4-WAY vaccine, but this difference was not statistically different (P=0.3057). It appears from this study that feedlot health parameters and some production costs can be improved for feeder cattle immunized for BRSV with an adjuvanted modified live antigen.