PSIV-B-14 - Fetal Programming Effects on Weight Gain and Backfat Thickness in Nellore Heifers

Abstract: Few studies have investigated the effects of fetal programming on the performance of heifers in the rearing phase This study evaluated the effects of maternal nutrition on performance and backfat thickness (BFT) of beef cattle heifers. The study comprised pregnant 126 Nellore dams, which were fixed time artificially inseminated (FTAI) with semen of four bulls. The animals were separated into three treatments: Not Programmed (NP), without protein-energy supplementation; Partially Programmed (PP), supplementation offered in the final third of gestation; and Full Programmed (FP), supplementation during the whole gestation. Animals were allocated to pasture paddocks with access to the supplement (0.03% live weight for NP, and 0.3% live weight for PP and FP) and water ad libitum. After calving, protein-energy supplementation ceased (average 220 days old), regardless of the treatment. After weaning, the female progeny (55 heifers) remained on the pasture until the beginning of the reproductive season at 24 months old. The performance of heifers was evaluated in the periods of weaning, year, 18 months and 24 months, measuring weight and backfat thickness (BFT). The effects of treatments (NP, PP, and FP) on phenotypes were evaluated using the analysis of variance and the means compared by the Tukey-Kramer test, with contrasts considered significant when p< 0.05. The weight of the animals showed a significant difference over time (p = 0.017). The weight of the heifers in the three treatments was similar in all periods evaluated (p > 0.05); however, when an analysis was carried out over time, a significant difference occurred among the treatments (p = 0.017). Fetal programming did not affect the weight and fat thickness of the heifers throughout the rearing period.