Pre-colostral antibodies to Neospora caninum in beef calves following an abortion outbreak and associated fall weaning weights

Abstract

Published reports have suggested that Neospora caninum infection may decrease milk production in dairy cows and affect rate of gain and feed efficiency in feedlot steers. This study examined whether there was an effect on the weaning weights of commercial beef calves. The outbreak involved a family-owned, 350-head cow-calf beef herd. Calves that developed antibodies to N. caninum during gestation were compared to calves with no evidence of infection. Blood samples were collected from calves before colostrum ingestion and from all cows after calving. Sera were analysed using a commercially available enzyme linked immunosorbent assay for N. caninum. Detailed individual calving records, birth, and weaning weights were available for all calves. Of the 180 samples collected from the cows and first-calf heifers after calving, 153 (85%) were positive for N. caninum. Seventy-five (67%) blood samples collected from 112 calves prior to colostrum ingestion also had positive antibody titres for N. caninum. Fall calf weights for calves with antibodies to N. caninum at birth were insignificantly different than those of calves with no antibodies (difference, -9.2 lb [-4.18 kg]; 95% CI, -31.3 to 12.8 lb), after adjusting for calf sex, dam age, calf birth weight, calf age at weighing, and sire group.