BVD CONSULT

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

*New Mexico State University Clayton Livestock Research Center, Clayton 88415; †Kansas State University College of Veterinary Medicine, Manhattan 66506; and ‡Vet Life, Overland Park, KS 66214

2Corresponding author: nelam@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 were fed common receiving, growing, and finishing diets for a 215-d period. Treatments were designed to 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), 2) PI-BVD calf commingled in the pen for 60 h and then removed (short-term exposure), and 3) PI-BVD calf commingled in the pen for the duration of the study (long-term exposure); and spatially exposed treatments were 1) negative control with no PI-BVD calf exposure (adjacent pen control), 2) PI-BVD calf commingled in the adjacent pen for 60 h and then removed (adjacent pen short-term exposure), and 3) PI-BVD calf commingled in the adjacent pen for the duration of the study (adjacent pen long-term exposure). Exposure to a PI calf transiently (60 h) or for the duration of the feeding period (215 d) did not affect (P ≥0.25) final BW compared with 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 the direct or spatially exposed groups. Likewise, total trial ADG was not affected (P ≥0.36) and overall efficiency of gain (P ≥0.19) was unaffected by PI-BVD calf exposure in the direct or spatially exposed groups. The 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 effects on health, performance, or carcass characteristics.

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

N. A. Elam*,2, D. U. Thomson† and J. F. Gleghorn ‡, 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, J Anim Sci 86: 1917-1924.

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