Effect of natural breeding of heifers to a bluetongue virus carrier bull

Abstract

Fourteen nulliparous heifers were impregnated over a period of one year by a bluetongue virus carrier bull known to shed bluetongue virus in his semen. All 14 heifers became viremic, but no readily apparent clinical sig s of bluetongue disease were seen. Two heifers did not conceive after inital insemination and were rebred twice before they were impregnated. One heifer aborted between 55 and 62 days after conception and was subsequently anestric for 300 days. This heifer was the only one of the 14 heifers to develop precipitating antibody to bluetongue virus, first detectable at 100 days after insemination. Thirteen of the 14 heifers calved after gestation periods ranging from 281 to 297 days (median = 288 days)/ Twelve calves were born alive and all exhibited varying degrees of congenital anomalies including excessive gingival tissue, crooked legs, macula on the skin of their noses and tilted jaws. Five calves were characterized as weak and ataxic at birth. One calf was dead at parturition and had to be removed by caecarean section. All live calves were viremic at birth.