Evaluation of the effect of cow exterior on calf size at parturition

Anotace: The aim of this research was to evaluate the effect of cow exterior on the weight of the calf at parturition and the size of the calf’s head. 453 purebred Holstein Friesian dairy cows at a selected farm were analysed within this research, and the measurements of the withers height, hip width, backside width and ischial width were taken from each specimen. Considering the calves, the measurements taken were the width and length of the head and weight at parturition. The research did not prove any significant (p>0.05) effect of the cow body conformation on any of the measured proportions of the calf. There was, however, a significant (p<0.05) difference in the head length and weight in calves in relation to the calving ease. As opposed to our expectations, the parturition weight of calves going through a more difficult parturition was lower (30.36 kg, as opposed to 36.57 kg in the less difficult parturition) and the length of the head was lower as well (23.47cm, as opposed to 23.98 cm in a less difficult parturition). At the same time, the weight and head length increased with each undergone lactation cycle of the mother – more specifically, this trend of increasing was observed from the first to the fifth lactation cycle. The parturition weight of calves was significantly affected by the gestation length itself. Another factors that had an effect on the weight and size of the calves were the season during which calving took place and the effect of the father bull. The results show a possibility of using the data collected in this research for breeding value estimation in difficult parturitions, since the effect of the father of the calf has to be taken into consideration as well as the effect of the the cow’s father.