Effects of long- or short-term exposure to a calf identified as persistently infected with bovine viral diarrhea virus on feedlot performance of freshly weaned, transport-stressed, beef heifers

¹ New Mexico State University Clayton Livestock Research Center, Clayton, NM 88415
² Kansas State University College of Veterinary Medicine, Manhattan, KS 66506
³ Vet Life, Overland Park, KS 66214

^* To whom correspondence should be addressed. E-mail: nelam{at}nmsu.edu.

	Abstract

A single experiment with a completely randomized design was conducted to evaluate the effects of long- or short-term exposure to a calf identified as persistently infected with bovine viral diarrhea virus (PI-BVD) on feedlot performance and carcass characteristics of freshly weaned, transport-stressed, beef heifers. Two hundred eighty-eight heifers that had been vaccinated for BVD before weaning and transport were processed and given a metaphylactic antibiotic treatment at arrival and fed common receiving, growing, and finishing diets for a 215-d period. Treatments were designed to either directly or adjacently expose the cattle to a PI-BVD heifer. Directly exposed treatments were: 1) negative control with no PI-BVD calf exposure (control, CON); 2) PI-BVD calf commingled in the pen for 60 h and then removed (short-term exposure, STE); and 3) PI-BVD calf commingled in the pen for the duration of the study (long-term exposure, LTE), and spatially exposed treatments were: 1) negative control with no PI-BVD calf exposure (adjacent pen control, APC); 2) PI-BVD calf commingled in the adjacent pen for 60 h and then removed (adjacent pen short-term exposure, APS); and 3) PI-BVD calf commingled in the adjacent pen for the duration of the study (adjacent pen long-term exposure, APL). Exposure to a PI calf either transiently (60 h) or for the duration of the feeding period (215 d) did not affect (P 0.25) final BW compared to heifers that were not exposed. Neither period nor overall DMI was affected (P 0.37) by PI-BVD calf exposure, and no differences (P 0.44) were observed between short- and long-term exposed heifers in either the direct or spatially exposed groups. Likewise, total trial ADG was not affected (P 0.36) and overall feed efficiency (P 0.19) was unaffected by PI-BVD calf exposure in either the direct or spatially exposed groups. Results from this study suggest that exposing previously vaccinated, freshly weaned, transport-stressed, beef calves to a calf that is persistently infected with bovine viral diarrhea virus has little, if any, marked affects on health, performance, and carcass characteristics.

Key Words: beef cattle, bovine viral diarrhea virus, feedlot, persistent infection