The investigation was carried out to evaluate the effects of two stocking rates (CA280= 280 kg LW/ha and CA=360= 360 kg LW/ha) and two weaning ages of calves (DC = Conventional weaning at seven months of age and DP= Early weaning at three/four months of age) on reproductive performance of primiparous beef cows of two breed compositions (½ Nelore ½ Hereford and ¼ Nelore ¾ Hereford). Average daily weight gain (GMD) from calving to DC, during the mating period, and in the period from DP to DC (GPC), the body condition score (CC) at beginning and at the end of mating period and at DC, the pregnancy rate (TP), and the calving interval (IEP) of the cows were evaluated. Cows managed under CA280 had significantly higher GMD than cows under CA360 in all three periods considered. Cows submitted to DP had higher GPC (P<0.01) than cows submitted to DC(0.539 vs. 0.257 kg/day, respectively). Cows under CA280 had signicantly higher CC from the beginning of the mating period to the date of DC than cows under CA360, while cows submitted to DP showed higher CC at the date of DC than cows submitted to DC under both stocking rates (4.33 vs. 3.68 for CA280 and 3.14 vs. 2.92 for CA360). The breed composition of the cows did not significantly influence on GMD and CC of the cows over the experimental period. The TP of cows under CA280 (67.56%) was significantly better than cows under CA360 (22.56%), as well as their IEP were significantly lower than cows under CA360 (395.4 vs. 409.9 days). Therefore, the lowest stocking rate allowed cows to better recover their weight and body condition after calving, causing improvement of conception rate and calving interval.
primiparous crossbred cows; reproductive performance; weaning age
