Efficacy of a control program for bovine trichomonosis based on testing and culling infected bulls in beef cattle managed under mountain pastoral systems of Northern Spain.

Bovine trichomonosis (BT) is a sexually transmitted disease that is considered a cause of early reproductive failure in cattle under extensive management conditions. Recently, Tritrichomonas foetus was detected in 41.5% of herds from one representative beef cattle breed (Asturiana de la Montaña; AM) reared in traditional mountain systems in Spain. The objective of the present study was to evaluate the effect of BT on reproductive performance and the economic consequences in AM herds. The benefits of a control program based on testing and culling infected bulls were also studied by comparing T. foetus prevalence and reproductive data before and after the implementation of the control measures. In infected herds, T. foetus infection increased calving intervals by 79 days (P<0.0001) and resulted in a higher percentage of cows-not-in calf (36% vs. 19%; P<0.001). An economic analysis showed that BT could reduce income by 68.7% in AM herds. The implementation of the control program decreased calving intervals (P<0.0001) and increased calving percentage (P<0.05). T. foetus prevalence showed a significant decline compared with the prevalence before implementing the control program (P<0.05). Nevertheless, after 2 years, the herd prevalence did not decrease (12.7-13.6%; P>0.05) and the herd incidence was 22.72%. The testing and culling policy was effective in improving reproductive efficiency but the complete elimination of BT without substantial changes in management appears unlikely because putative risk factors associated with the disease are present in the management of this breed.