Relação entre os hormônios metabólicos IGF-1, leptina e GH e eficiência reprodutiva em fêmeas Nelore
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2016-12-12
Autores
Peres, Rogério Fonseca Guimarães [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os hormônios metabólicos IGF-1, GH e leptina são alterados de acordo com o status nutricional dos animais. O objetivo desse trabalho foi determinar as concentrações desses hormônios em vacas paridas e novilhas Nelore entre 12 e 16 meses de idade e seus efeitos na reprodução nos experimentos do Capítulo 2. No Capítulo 3, vacas primíparas, multíparas e novilhas Nelore de dois anos foram suplementadas ou não com milho moído durante o protocolo de IATF até o diagnóstico de gestação com o intuito de avaliar a alteração nos hormônios metabólicos e seus impactos na reprodução. No Capítulo 4, multíparas Nelore de duas fazendas foram suplementadas ou não com virginiamicina adicionada ao sal mineral. Em todos os experimentos as fêmeas foram submetidas a protocolos de IATF e colocadas com touro até o fim da estação de monta, sendo que apenas nos experimentos do Capítulo 3, as fêmeas receberam segunda IATF caso estivessem vazias antes da entrada dos touros. No experimento 1 do Capítulo 2 e no experimento 1 do Capítulo 3 houve efeito linear positivo da concentração de IGF-1 no dia da inseminação na probabilidade de prenhez a IATF. Em todos os experimentos realizados, também houve efeito linear positivo da concentração de IGF-1 no dia da inseminação na probabilidade de prenhez ao final da estação de monta, exceto no experimento 2 do capítulo 2. A concentração de IGF-1 no diagnóstico de gestação apresentou efeito linear negativo na probabilidade de prenhez em quatro estudos. O efeito do GH e da leptina nos parâmetros reprodutivos não foi consistente entre os estudos. A suplementação com milho não alterou a taxa de prenhez à IATF, mas houve tendência no aumento da prenhez na segunda inseminação e aumentou a taxa de prenhez ao final da estação de monta de primíparas, diminuiu a taxa de prenhez ao final da estação de monta em multíparas e aumentou somente o peso a desmama dos bezerros de primíparas. A suplementação com virginiamicina não aumentou a taxa de prenhez a IATF e ao final da estação de monta na Fazenda A, enquanto que na fazenda B não aumentou a taxa de prenhez a IATF, mas aumentou a porcentagem de fêmeas ciclando no diagnóstico de gestação e uma tendência no aumento da probabilidade de prenhez ao final da estação de monta. O peso a desmama aumentou em ambas fazendas com suplementação de virginamicina. Conclui-se que o IGF-1 no momento da IA e no momento do DG são possíveis importantes marcadores de fertilidade em bovinos e que estratégias nutricionais podem alterar esses hormônios com ou sem impacto na reprodução.
The metabolic hormones IGF-1, GH and leptin change according to nutritional managmentof the herd. The aim of these trials was to measure the concentration of these metabolic hormones in 12-16 months old Nellore heifers and multiparous cows and associate with the reproduction performance in experiments of Chapter 2. In Chapter 3, 2-years old heifers, primiparous and multiparous Nellore cows received or not ground corn starting in the begginning of TAI protocol until pregnancy check on day 30 to associate with metabolic hormones and reproduction. In Chapter 4, multiparous Nellore cows of two farms were supplemented or not with virginiamycin in mineral salt and the association with metabolic hormores and reproduction was evaluated. In all studies TAI was performed and bulls stayed from 7 days after TAI until the end of breeding season, except on trials of Chapter 3, which second TAI was performed in open cows before being exposed to bulls. In experiment 1 of Chapter 2 and experiment 1 of chapter 3 there was a linear positive effect of IGF-1 concentration on day of insemination on TAI pregnancy rate. In all trials, IGF-1 concentrations on insemination had a linear positive effect on pregnancy rate in the end of breeding season, except in experiment 2 of chapter 2. The IGF-1 concentrations on pregnancy rate had a linear negative association with TAI pregnancy rate in 4 studies. Concentraions of GH and leptin had no consistent association with reproduction rates. Corn supplementation did not alter TAI pregnancy rate, but tended to improve pregnancy rate on second AI and increased final pregnancy rate in primiparous cows, reduced final pregnancy rate in multiparous cows and increased weaning rate of primiparous calves supplemented with corn. Virginiamycin supplementation did not increase TAI and final pregnancy rates in farm A, while farm, B did not increase TAI pregnancy rate, but increased the percentage of cycling cows on pregnancy check and tended to increase final pregnancy rate in the end of the breeding season. In both farms, calves weaning weight increased with virginiamycin supplementation. In conclusion, IGF-1 concentrations on TAI and pregnancy check can be possible markers for fertility in Bos indicus cows and nutritional strategies can change metabolic hormones affecting or no reproduction parameters.
The metabolic hormones IGF-1, GH and leptin change according to nutritional managmentof the herd. The aim of these trials was to measure the concentration of these metabolic hormones in 12-16 months old Nellore heifers and multiparous cows and associate with the reproduction performance in experiments of Chapter 2. In Chapter 3, 2-years old heifers, primiparous and multiparous Nellore cows received or not ground corn starting in the begginning of TAI protocol until pregnancy check on day 30 to associate with metabolic hormones and reproduction. In Chapter 4, multiparous Nellore cows of two farms were supplemented or not with virginiamycin in mineral salt and the association with metabolic hormores and reproduction was evaluated. In all studies TAI was performed and bulls stayed from 7 days after TAI until the end of breeding season, except on trials of Chapter 3, which second TAI was performed in open cows before being exposed to bulls. In experiment 1 of Chapter 2 and experiment 1 of chapter 3 there was a linear positive effect of IGF-1 concentration on day of insemination on TAI pregnancy rate. In all trials, IGF-1 concentrations on insemination had a linear positive effect on pregnancy rate in the end of breeding season, except in experiment 2 of chapter 2. The IGF-1 concentrations on pregnancy rate had a linear negative association with TAI pregnancy rate in 4 studies. Concentraions of GH and leptin had no consistent association with reproduction rates. Corn supplementation did not alter TAI pregnancy rate, but tended to improve pregnancy rate on second AI and increased final pregnancy rate in primiparous cows, reduced final pregnancy rate in multiparous cows and increased weaning rate of primiparous calves supplemented with corn. Virginiamycin supplementation did not increase TAI and final pregnancy rates in farm A, while farm, B did not increase TAI pregnancy rate, but increased the percentage of cycling cows on pregnancy check and tended to increase final pregnancy rate in the end of the breeding season. In both farms, calves weaning weight increased with virginiamycin supplementation. In conclusion, IGF-1 concentrations on TAI and pregnancy check can be possible markers for fertility in Bos indicus cows and nutritional strategies can change metabolic hormones affecting or no reproduction parameters.
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Palavras-chave
Reprodução, Status metabólico, Suplementação de vacas, Cows supplementation, Metabolic hormones, Reproduction