Reproductive problems associated with bluetongue virus activity in Nebraska

Abortions, stillborn calves, neonatal mortalities and excessive numbers of weak, slow-starting newborn have contributed to significant losses within the valuable breeding herds at the Roman L. Hruska U.S. Meat Animal Research Center. Conception rates of 70 to 80%, abortion storms and neonatal mortality of 5 to 25% have been observed. Vaccination programs control most of the common diseases that contribute to production losses. Management and nutrition are considered adequate. Excessive dystocia is thought to contribute to some of the excessive losses reported. Diagnostic efforts and epidemiological studies indicate that bluetongue virus (BTV) appears to be associated with some of the reproductive losses. Serotypes 11 and 13 have been isolated. Bovine virus diarrhea virus has also been isolated from weak calves that die at birth or shortly after birth. Serological studies reveal a periodically high incidence of bluetongue (BT) positive breeding animals. Collaborative efforts continue and must be expanded to further elicit the cause and economic impact of reproductive loss at the Meat Animal Research Center.