Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano.

O objetivo deste trabalho foi avaliar os efeitos da intensidade do ganho de peso no período de recria, dos 13 aos 18 meses de idade, sobre a taxa de prenhez de novilhas de corte acasaladas com o sobreano durante o outono. Os tratamentos foram constituídos de 30 novilhas com peso médio de 208 kg, submetidas a ganho médio de 0,595 kg dia-1 (G600), 41 novilhas com peso médio de 197 kg submetidas a ganho médio de 0,656 kg dia-1 (G700) e 58 novilhas com peso médio de 181 kg submetidas a ganho médio de 0,723 kg dia-1 (G800). Foram avaliados os efeitos dos tratamentos sobre peso, escore de trato reprodutivo e taxa de prenhez. As taxas de prenhez foram 30,0% 47,8% e 50,0% para os grupos G600, G700 e G800, respectivamente, não existindo diferença significativa entre os grupos. Os grupos G700 e G800, submetidos à maior taxa de ganho de peso, apresentaram maiores valores de escore de trato reprodutivo em relação ao G600 no início da estação de monta. Novilhas com escores mais elevados apresentaram tendência a maior taxa de prenhez. A taxa de prenhez esteve associada à intensidade de ganho de peso na recria independentemente das variações de peso no acasalamento.The objective of this work was to evaluate the effects of growth rate during rearing period, from 13 to 18 months, on pregnancy rate of beef heifers mated at yearling during autumn. Treatments consisted of 30 heifers weighing on average 208 kg submitted to average growth rate of 0.595 kgday-1 (G600), 41 heifers averaging 197 kg with average growth rate of 0.656 kgday-1 (G700) and 58 heifers with 181 kg with average growth rate of 0.723 kgday-1 (G800). Treatment effects were determined on body weight, reproductive tract score and pregnancy rate. Pregnancy rate was 30.0% 47.8% and 50.0%, respectively, for G600, G700 and G800, without significant differences among groups. Treatments G700 and G800, with large growth rates, showed higher values of reproductive tract score than G600 at the start of the mating period. Heifers with higher scores had a tendency to present higher pregnancy rates. Pregnancy rates were related to growth rate during postweaning independently of weight variations at mating

Development and reproductive performance of beef heifers supplemented with brown rice meal and/or protected fat on temperate grasslands

The response of energy supplementation was evaluated on the development and reproductive performance of beef heifers on temperate grasslands. Twenty-eight Charolais × Nellore heifers, with initial average age of 18 months and initial live weight of 274.9 kg were utilized. The animals were maintained on oat + ryegrass pasture and distributed in the following treatments: no supplementation (NS): heifers kept exclusively on pasture; MEG: supplementation with protected fat Megalac®; BRM: supplementation with brown rice meal; BRM+MEG: supplementation with BRM + protected fat. The average final weight of the heifers was of 403.4 kg and corresponded to 89.5% of the adult weight. The body condition of heifers increased linearly with daily increase of 0.012 points, correlating positively with the final weight. There was interaction between treatment and period for average daily weight gain. The highest daily weight gain, 1.395 kg, occurred in the first period when the animals were supplemented with BRM+MEG. In the last period, the NS animals presented the lowest daily weight gain, 0.888 kg. Supplementation with brown rice meal and/or protected fat does not interfere in the intake of pasture by heifers or increase the total intake of dry matter, not changing, therefore, the average daily weight gain at the end of the period of grazing. The daily weight gain does not change during supplementation. The use of temperate pasture with and without supplementation promotes the proper development of the structure and reproductive tract of heifers, benefiting the animal performance indexes in the first mating at 25-27 months of age