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Effect of chronic infusion of leptin and nutrition on sexual maturation of Bos indicus heifers

Grant number: 07/06323-5
Support type:Scholarships in Brazil - Master
Effective date (Start): August 01, 2008
Effective date (End): January 31, 2010
Field of knowledge:Agronomical Sciences - Animal Husbandry - Animal Production
Principal Investigator:Luis Felipe Prada e Silva
Grantee:Marina Vieira de Carvalho
Home Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Nelore breed (Bos indicus) form the basis of the beef cattle industry in Brazil. The Nelore is better adapted to tropical conditions, but has slow sexual maturation, which limits the slaughter rate of the herd. The physiological mechanism regulating puberty is not well understood, however, several research evidences suggest leptin as a major limitation to sexual maturation in undernourished heifers. Leptin plasma concentration is strongly related to the animal body condition, and heifers that attain puberty earlier have higher leptin expression in the adipose tissue. This study has the objective to test the hypothesis that increasing leptin concentration through exogenous infusion or through increasing daily intake of energy is capable to induce puberty in Bos indicus heifers. Twenty four non-pubertal heifers, between 18-22 months of age, will be divided in three experimental groups: low energy (LOW), high energy (HIGH) or low energy with administration of recombinant ovine leptin (LOW+LEPTIN). Heifers will be maintained in lots until confirmation of first ovulation. Feeding will be controlled individually with electronic gates (Calan). Among the 16 heifers in the low energy diet, eight will be randomly selected to receive subcutaneous injection of leptin during 40 days. The sexual maturity of the heifers will be monitored by ultrasonography and by progesterone plasmatic concentration. Plasma samples will be collected during the experiment to determine progesterone and leptin concentrations. We expect that the chronic administration of leptin will signalize to the hypothalamus of the undernourished heifers the existence of an adequate supply of energy, allowing puberty to occur. The elucidation of the mechanism governing sexual precocity in zebu heifers is important for the development of therapeutic protocols to induce puberty, and for the development of more efficient breeding programs to obtain lineages of zebu cattle with better sexual precocity. (AU)

Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
CARVALHO, Marina Vieira de. Efeito do Fornecimento Crônico de Leptina e da Nutrição na Maturação Sexual de Novilhas Zebuínas (Bos taurus indicus). 2009. Master's Dissertation - Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia Pirassununga.

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