Grazing behaviour of dairy cattle in relation to genetic selection for milk production

The present study was designed to examine effects of selection for milk production on the grazing behaviour of dairy cattle. Subjects were 43 Holstein Friesian cows from the Langhill Dairy Herd in Edinburgh which consists of two genetic lines: one selected for high milk solids yield and a control line of average genetic index for milk solids yield. Their behaviour was recorded in various observation periods, additionally herbage intake on pasture was investigated. No significant influence was found of either milk yield or breeding value on time spent grazing, lying, ruminating or standing or on bite rate. The influence of stage of pregnancy was stronger, however, results for heifers and cows were contrary. Heifers and cows of the selected line had higher herbage intakes than animals of the control line.