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Semen characteristics and sexual maturity of young Tabapuã (Bos taurus indicus) bulls under different feeding management

Body weight (BW), scrotal circumference (SC), semen characteristics and Breeding Soundness Evaluation-Zebu (BSE-Z) of 516 young Tabapuã breed bulls, raised under different feeding regimen, were evaluated for one year old bulls (12-17 months of age) and two year old bulls (21-27 month of age). The feed regimens were the following: feeding regimen 1 - animals raised under pasture condition plus mineral supplementation, feeding regimen 2 - animals raised under pasture condition and supplemented during the dry season with sugar cane and urea (0.5%) plus 2kg/animal/day of a commercial concentrate (84%NDT and18% crude protein) fed twice a day, and feeding regimen 3 - feed lot animals fed balanced diets with the following composition: sugar cane, elephantgrass, urea (0.5%) and commercial concentrate (88%NDT and 19%crude protein) varying from 2kg/animal/day for young animals to 6kg/animal/day at adult age (27 months), fed three times a day. One year old animals on feeding regimen 3 were heavier (BW=416kg), and had higher (P<0,05) scrotal circumference (29.6cm), semen volume (5.7ml) and spermatic motility (42%) than animals on feed regimens 1 and 2. No difference between animals on feeding regimens 1 and 2 were observed for BW (232.44 and 279.34kg), scrotal circumference (20.02cm and 22.16cm), semen volume (2 and 2.12ml), and spermatic motility (14.17% and 20.27%), respectively. Two years old animals on feeding regimen 3 were heavier (BW=490.82kg), and had higher scrotal circumference (SC=33.56cm) and andrologic classification (ACP=71.71) than animals on feeding regimens 1 and 2, which showed, BW (378.91 and 409.2kg), SC (30.66 and 30.31cm) and ACP (63.55 and 66.05), respectively. Difference between animals on feeding regimen 3 and animals on regimens 1 and 2 were observed for BW, SC and SV. Mature animals showed BW=497.5kg, SC=33.81cm and SV=4,83ml. Animals on feeding regimen 1 (BW=388.53kg, SC=30.81cm and SV=2.92ml), were not statistically different from animals on feeding regimen 2 (BW=412.32kg, SC=31.56 cm and SV=3.93ml). Immature animals were heavier (BW=479.22kg) and had higher SC (SC=32.96cm) on feeding regimen 3, than animals on feeding regimen 1 (BW=367.36 and SC=29,56cm), and animals on feeding regimen 2 (BW=402.69kg and SC=29.55cm). Feed supplementation influences reproductive performance, and shows positive effect on body weight, scrotal circumference, physicals characteristics of semen and BSE of young Tabapuã bulls.

bull; feeding regimen; seminal characteristic; Tabapuã; young bull; sexual development


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