पशु चिकित्सा विज्ञान एवं प्रौद्योगिकी

Bovine Viral Diarrhea Milk ELISA Test Detecting Anti-p80 Antibody Association with Milk Handling Methods and Cow Characteristics

Abstract

David J. Wilson, Kerry A. Rood and Gregory M. Goodell

A milk ELISA test for Antibody (Ab) against Bovine Viral Diarrhea (BVD) virus was studied in a dairy herd with past diagnoses of calves dying from BVD and Persistently Infected (PI) cows, with culling of all known PI cows. Modified live BVD vaccine was administered to calves 3 months and 4 months old, all cows at dryoff 45 to 60 days before calving, and 15-21 days in milk (DIM). Cows were tested 1 month apart (247 and 258 cows, respectively) using a competitive ELISA for milk Ab binding to p80 BVD non-structural protein. Results are reported as % binding by a second Ab; higher second Ab binding means the milk had less anti-p80 BVD Ab. Cows with 90-100% binding in milk on both tests were classified as low Ab–interpreted as a cow with PI or vaccine failure. Milk handling method was significant; fresh milk mean 49% second Ab binding was higher than for milk preserved 3 other ways. In fresh milk, 15 cows had 90-98% binding on one test, but 14/15 were milking during both herd tests and were below 90% on the other tests. Stage of lactation significantly affected results; anti-BVD Ab was higher from 1-30 DIM and lower from 61-150 DIM than at other stages of lactation. Ear notches were sampled concurrently from all cows for BVD antigen capture ELISA testing. Neither the milk ELISA results (no cows > 90% second Ab binding on both milk tests) nor ear notch testing classified any cows as PI animals. The milk BVD test might be useful to the dairy industry as a practical and convenient test for screening herd replacements, especially when large numbers of lactating cows are purchased and mixed into different pens throughout a dairy herd.