The objective of this work was to evaluate the feed systems for 70 primiparous beef heifers from the initial gestation period at the age of 13/15 months to the end of the second reproductive period as primiparous cows at 22/24 months of age. The experimental design was fully random with plots subdivided in time considering animals as replicates. The initial mean live weigh was 282 kg and the initial mean body condition was 3.2. The feeding systems were proposed to obtain higher live weight gain at initial (PCIG) or final (PCFG) gestation period: PCIG - pregnant heifers on pearl millet pasture (Pennisetum americanum, L.) during the initial gestation period and on natural pasture at pre-calving period; PCFG - pregnant heifers on natural pasture during the initial gestation period and on oat (Avena strigosa Schreb) and annual ryegrass (Lolium multiflorum Lam) pasture at pre-calving period. At initial gestation period, the mean live weight gain of 0.424 kg of PCIG heifers was higher than 0.245 kg of PCFG heifers. In the pre-calving period, PCIG heifers lost weight, 0.303 kg/day and presented BC of 0.77, while PCFG heifers gained 0.901 kg/day and presented BC of 0.37. The weight of 323 kg and body condition of 3.3 of post-calving PCFG heifers were higher than 274 kg and BC of 2.6 of PCIG heifers, respectively. PCFG heifers had calves 4 kg heavier. In the beginning of the second reproduction period, PCFG cows were 35 kg heavier and presented BC of 0.60. The pregnancy rate of 85% of PCFG heifers was higher than 53% of PCIG heifers. Pregnant cows had the highest body condition rate at calving and at the beginning of the second reproduction period, presented higher calving and mating interval and heavier calves.
body condition; dystocia; calving; live weight; grazing systems
