Milking Performance and Reproductive Efficiency of Dairy Cows in an Environmentally Controlled Structure

Effects of a controlled environment on production and reproduction were evaluated with four groups of cows: T1, remained outside 24 h; T2, inside from 1930 h to 0530 h; T3, inside from 0530 h to 1930 h; T4, inside 24 h. Average daily degree-hours above 21 C (T 1 to T~) for 1970 (148 days) and 1971 (79 days) were 100, 84, 41, 11 and 71, 62, 19, 0. Milk yield, fat percentage, fat yield, 4% fat-corrected milk, and conception rates were improved by controlled environment. ~t squares adjusted, 4% fatcorrected milk yields daily (kg, 208 cows overall) were T1, 14.23; T2, 14.48; Ts, 14.96; T4, 15.57. Conception rates to all services (n=305) were Ta, 28.1%; Tz, 28.4%; T3, 40.0%; T4, 38.8%.