Reproductive Loss due to pestivirus infection in dairy cattle herds in Thailand

Abstract

Infection with bovine pestivirus, Bovine Viral Diarrhoea Virus (BVDV), causes significant loss in cattle production worldwide. A new type of bovine pestivirus, atypical pestivirus, was identified in natural infected calf firstly in Khon Kaen, Thailand in 2004. The epidemiological studies have been done in the area, but loss in reproduction due to the infection has never been accessed. This study aims to investigate losses in herd's reproduction and update epidemiological data in the population where atypical pestivirus was found. During 2008-2009, 420 dairy herds in the area were classified according to infective status into high-positive and non-infective herds by antibody analysis in bulk tank milk samples. Data of reproduction of cows in both groups, at the same proportion, with 4 indices, i.e. calving to first service interval (CFS), calving to conception interval (CCI), calving interval (CI) and overall pregnancy rate, were compared by t-test. The CSF, CCI, CI and overall pregnancy rate of the high-positive herds were significantly (p<0.05) poorer than the non-infective herds; 121 vs 89 days, 170 vs 127 days, 450 vs 406 days and 49% vs 57%, respectively. Moreover, the proportion of the high-positive herds did not change from the 4-year earlier investigation, indicating that the virus still circulates in the area and may cause losses in Thai dairy production in the near future.