Efecto de la fecha de parto sobre características productivas y reproductivas de vacas Charolais

Abstract

Effect of Calving date on Reproductive and Productive Characteristics of Charolais Cows. In order to assess, along two consecutive years, the effect of the calving date on postpartum reproductive and productive characteristics of meat-producing Charolais cattle with a short-term breeding time and annual free range grazing. A group of 1,665 records belonging to 583 Charolais cows, for two consecutive years, were analyzed. The records were grouped according to birth date into four calving groups (G1=1-21, G2=22-42 =, G3 = 43-63, and G4>63) of 21 consecutive days. A completely randomized design, with different numbers of replications and covariates was applied. There was not a significant effect (P> 0.05) from calving date on the weight at birth of calves. The weaning weight of calves born in G1 in two consecutive years, was higher than those born in groups G2, G3 and G4. Calves born in G4 had a higher preweaning daily gain in both years (P <0.05) than those born in the groups G1, G2 and G3. G1 cows weaned in two consecutive years 26, 46 and 69 kg/calf over the cows of groups G2, G3 and G4. The mating and pregnancy days were inverse to those of the calving group, while the open days showed a direct dependence of these two variables, G1 cows became pregnant 11, 25 and 41 days before the cows in groups 2, 3 and 4. The days to next calving and Julian day following calving increased from G1 to G4 and both were inverse to the interval between calvings. It is concluded that matings of 90 days in summer, cows calving in early spring have a better productive and reproductive postpartum behavior.