Effect of feeding systems on weight gain and reproductive performance of Nellore heifers bred at the age of 17/18 months

[摘要] - Using a linear statistical model (GLM/SAS) the reproductive performance and growth of 480 Nellore heifers were evaluated from the age of 7.5 to 17/18 months under four feeding systems during the dry period (96/05 to 96/10): Brachiaria brizantha cv. Marandu pasture (B); Brachiaria brizantha cv. Marandu pasture + Anipro (BA); Pennisetum americanum cv. (L.) Leeke (Pearlmillet) (M) and Brachiaria brizantha cv. Marandu pasture + Sal Ouro (BS). At the end of supplementation all heifers were moved to a paddock of Panicum maximum cv. Mombaça pasture, 1 AU/ha, from 96/10 until the end of the mating season (97/03 to 97/05). Parameters like liveweight (LW), body condition score (BCS), liveweight daily gain (LDG), age at mating (AM), pregnancy rate (PR) and age of the dam (AD) were determined. Besides these variables pregnant and non-pregnant heifers were also evaluated for scores of conformation (Cs), precocity (Ps) and muscularity (Ms). The systems BA and M registered significantly differences with major LW, LDG and BCS values after the dry season compared to systems B and BS. At the beginning of the mating season LW values from B, BA and M were different of BS system. At the end of the mating season no differences could be detected among the four systems regarding LDG, BCS, AM, and AD. No significant effect on the PR averages of the four feeding systems B, BA, M e BS was registered (22,2%, 24,2%, 20,7% e 13,8%). Significant differences (P<0.01) between pregnant and non-pregnant Nellore heifers could be detected for LW, BCS, AM, LDG, Cs, Ps, and Ms.

[学科分类] 兽医学

[关键词] mating at 17/18 months;Nellore;heifer feeding systems   IntroduçãoO desenvolvimento de fêmeas de reposição é uma fase crítica em sistemas de produção de pecuária de corte