Productive and Reproductive Analysis of Dual-Purpose Bos taurus x Bos indicus Cows in Subtropical Humid Climate

The objective was to evaluate the effect of some environmental factors on milk yield (per lactation, per day (d) and per calving interval), lactation length and reproduction (age and weight at first breeding, age at first calving, calving interval) of Holstein x Zebu and Brown Swiss x Zebu cows in the humid subtropics of Puebla, Mexico. Cows (n=154) were kept in a rotational grazing system on pastures with Brachiaria brizantha. In addition, cows received 2 kg/animal/d of concentrate (70% total digestible nutrients and 16% crude protein) and minerals on an ad libitum basis; between November and May, cows were offered 15-20 kg/animal/d of chopped Japanese cane (Saccharum sinense). Cows were milked twice a d, by machine. Calves were used to stimulate milk ejection of their dams. Variables were evaluated via analysis of variance with a statistical model that included year of first breeding (20102013) or year of calving (2008-2013), season of calving (rainy, windy, dry) and lactation number (1, 2, 3 or more), except for age and weight at first breeding, and age at first calving. Calving season affected (P<0.05) milk yield per lactation and milk yield per day. Calving number only affected (P<0.01) milk yield per day and milk yield per calving interval. Overall adjusted means for milk yield per lactation, per day and per calving interval, lactation length, weight and age at first breeding, age at first calving and calving interval were: 2870 kg, 8.53 kg, 6.61 kg, 332 d, 330 kg, 784 d, 1101 d and 462 d, respectively. Overall means of milk yield and of reproductive traits of the present study are acceptable for subtropical environmental conditions.