Resumo:O presente trabalho teve como objetivo avaliar diferenças na idade e peso à puberdade entre novilhas Nelore (260±34 kg; 12±1 meses de idade) tratadas com salina (n=15) ou somatotrofina bovina recombinante (rbST; n=16) a cada 14 dias desde os 12 até os 22 meses de idade, ou até atingir a puberdade. Adicionalmente, verificamos o efeito do rbST sobre o crescimento, o revestimento de gordura subcutânea, as concentrações plasmáticas de GH, IGF-I, leptina, glicose e insulina, e a taxa de prenhez na primeira estação de monta. Todas as novilhas foram mantidas à pasto no mesmo piquete e foram expostas durante todo o experimento a um rufião com buçal marcador. O peso corporal e a espessura da gordura subcutânea foram mensurados a cada dois meses durante o período experimental. Avaliação por ultrassom dos ovários para monitorar a presença de CL e amostras de sangue foram coletadas a cada 14 dias para quantificações hormonais. Não houve efeito do tratamento (p≥0,05) na idade e peso à puberdade, ou taxa de prenhez na primeira estação de monta. A espessura da gordura subcutânea entre a 12ª e 13ª costela não foi alterada pelo tratamento (p≥0,05), no entanto a espessura da gordura subcutânea na garupa foi menor nas novilhas do grupo rbST aos 18 (p=0,04) e 22 (p<0,01) meses de idade. Não houve efeito de tratamento (p≥0,05) sobre o ganho de peso e as concentrações plasmáticas de glicose, GH e IGF-I. O diâmetro do maior folículo foi menor nos animais do grupo salina aos 12 meses de idade (p= 0,01) e se correlacionou com a concentração de IGF-I no grupo rbST (r= 0,13; p=0,05). No grupo salina a concentração de leptina foi maior aos 12,7 (p=0,02), 13,4 (p= 0,01), 14,3 (p=0,04) e 16,2 (p=0,03) meses de idade e a concentração de insulina foi maior aos 20,1 meses de idade (p=0,06). Em resumo, o tratamento prolongado com 250 mg de rbST não alterou a idade ou peso...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract:The present experiment evaluated differences in age and weight at puberty between Nellore heifers (260±34 kg; 12±1 months old) treated with saline (n=15) or recombinant bovine somatotropin (rbST; n=16) every 14 days from 12 until 22 months of age or until puberty attainment. Additionally, we assessed the effect of rbST in subcutaneous fat thickness, plasma GH, IGF-I, leptin, glucose, insulin, and pregnancy in the first breeding season. All heifers were maintained on the same pasture and exposed to a teaser bull with a neck-marker device. Heifers body weight and subcutaneous backfat thickness were obtained every two months, ovaries were evaluated by ultrasound and blood samples collected every 14 days to monitor the presence of CL and plasma hormones concentration. There was no effect of treatment (p≥0.05) on age and weight at puberty or pregnancy in the first breeding season. The backfat thickness between the 12th and 13th rib was not affected by treatment (p≥0.05), however the rump backfat thickness was lower in rbST heifers at 18 and 22 months (respectively, p=0.04; p<0.01). Treatments had no effect (p≥0.05) on weight gain, plasma glucose, GH and IGF-I. The diameter of the largest follicle was smaller in animals of the saline group at 12 months of age (p=0.01) and was correlated with plasma IGF-I in the rbST group (r=0.13; p=0.05). In the saline group, leptin concentration was higher at 12.7 (p=0.02), 13.4 (p=0.01), 14.3 (p=0.04) and 16.2 (p=0.03) months, and insulin concentration was increased at 20.1 months of age (p=0.06). In summary, prolonged treatment with rbST did not change the weight or age at puberty, plasma glucose, GH and IGF-I, however it decreased subcutaneous fat and insulin, increased leptin concentration. It was demonstrated that treatment with rbST did not affect pregnancy in the first breeding season. / Orientador:Guilherme de Paula Nogueira / Banca:Maria Carolina Villani Miguel / Banca:José Fernando Garcia / Mestre

Made available in DSpace on 2016-09-27T13:40:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-03. Added 1 bitstream(s) on 2016-09-27T13:45:18Z : No. of bitstreams: 1 000870579.pdf: 703160 bytes, checksum: f55637ae1394eb036e933d15f2866a88 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The present experiment evaluated differences in age and weight at puberty between Nellore heifers (260±34 kg; 12±1 months old) treated with saline (n=15) or recombinant bovine somatotropin (rbST; n=16) every 14 days from 12 until 22 months of age or until puberty attainment. Additionally, we assessed the effect of rbST in subcutaneous fat thickness, plasma GH, IGF-I, leptin, glucose, insulin, and pregnancy in the first breeding season. All heifers were maintained on the same pasture and exposed to a teaser bull with a neck-marker device. Heifers body weight and subcutaneous backfat thickness were obtained every two months, ovaries were evaluated by ultrasound and blood samples collected every 14 days to monitor the presence of CL and plasma hormones concentration. There was no effect of treatment (p≥0.05) on age and weight at puberty or pregnancy in the first breeding season. The backfat thickness between the 12th and 13th rib was not affected by treatment (p≥0.05), however the rump backfat thickness was lower in rbST heifers at 18 and 22 months (respectively, p=0.04; p<0.01). Treatments had no effect (p≥0.05) on weight gain, plasma glucose, GH and IGF-I. The diameter of the largest follicle was smaller in animals of the saline group at 12 months of age (p=0.01) and was correlated with plasma IGF-I in the rbST group (r=0.13; p=0.05). In the saline group, leptin concentration was higher at 12.7 (p=0.02), 13.4 (p=0.01), 14.3 (p=0.04) and 16.2 (p=0.03) months, and insulin concentration was increased at 20.1 months of age (p=0.06). In summary, prolonged treatment with rbST did not change the weight or age at puberty, plasma glucose, GH and IGF-I, however it decreased subcutaneous fat and insulin, increased leptin concentration. It was demonstrated that treatment with rbST did not affect pregnancy in the first breeding season. / FAPESP: 2012/143687