An economic evaluation of the main causes of infertility in the Scottish beef suckler herd
In this study, a Markov chain model based on the cow’s reproductive cycle, and a financial model were developed to study the variation in profitability in Scottish beef suckler herds resulting from the effect on fertility of disease and/or the employment of alternative management practices. The factors affecting fertility to be economically evaluated were chosen based on the results of the regression analysis combined with the recommendations from the literature. The selected factors were: LBS, feeding management, bull management, the effect of animal disease, i.e. BVDV, and restricted suckling. Feeding management was found to be the most important factor diminishing the financial performance of suckler herds. The total gross margin (GM) was found to diminish by 25% between the optima as a result of the application of a poor and a moderate feeding regimes combined with alternatives lengths of breeding season (LBS) ranging from 42 to 147 days. There were also interactions between the effect of poor bull performance and the LBS so that the effect of poor bull performance is markedly increased by the employment of a short LBS. The losses produced by a BVDV infection varied depending on the proportion of animals of the herd infected by this virus, which varies over time. This aspect was estimated using the model of Gunn et al. (2004), which then provided inputs for the estimation of reproductive performance and gross margins using the models reported here. It was found that BVDV drops profitability of Scottish beef suckler herds by up to 23%. Finally, when restricted suckling was applied for alternative LBS and compared with the economic performance as a result of the application of ad libitum suckling, it was found that profitability was improved by 14% between the two optima.