3:10 PM - 3:20 PM
[III-16-22] Effect of season on feed intake and milk production in cows managed by robotic milking system
[Introduction] Environment temperature affects milk production. This study compared the seasonal difference between winter and summer in the milk production of lactating dairy cows managed by the robotic milking system. [Methods] The two experiments lasted for two weeks were arranged during winter (Feb) and summer (Aug) in a free stall barn with a robotic milking and ventilation fans, under the long-day photoperiod management. In each season, two levels (8 or 5 kg/d) of concentrates were provided for high and low yield cows (total 16 cows), respectively, during milking. Cows were offered similar partial mixed rations (PMR, TDN 69% of dry matter) from 10:00 to 16:00 in each season. [Results] Milking frequency, milk yield, milk composition and PMR intake were not different between the seasons. Eating time during daytime in summer was shorter compared to that in winter, while daily rumination time was longer in summer. Rumen pH and acetate proportion were higher in summer. These results indicate that thermal environment little affects milk production of robotic milking cows under the controlled ventilation despite the changes in the eating and rumination behaviors