Rumination time, milk yield, milking frequency of grazing dairy cows milked by a mobile automatic system during mild heat stress

摘要

Cows milked by automatic systems (AS) are most often confined indoors or have access to pasture only during the day in summer. However, grazing allows decreasing feeding costs and improves animal health and welfare. A mobile AS, as described by Dufrasne et al. (2010), allowing grazing of dairy cows in fragmented areas is thus advantageous for animals. At grazing, the cows can move more largely than at barn and are submitted to environmental conditions. During heat stress (HS) periods, it is known that feed intake can be reduced, especially with temperature above 25°C or 26°C (Rhoads etal., 2013). Little information exists on effects of HS on grazing dairy cows milked by an AS. The aim of this study was to determine the effects of HS periods on themilk yield, milking frequency, fat to protein ratio in milk (F/P) and rumination time (RT) of grazing dairy cows milked by an AS located on pasture.