IGF-1, leptin and GH concentrations and its effects on reproduction in Nellore cattle.

Author(s)

Rogério Fonseca Guimarães Peres

• Document type: Doctoral Thesis
• Press: Botucatu. 2017-01-17.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Medicina Veterinária e Zootecnia. Botucatu
• Defense date: 2016-12-12
• Advisor: José Luiz Moraes Vasconcelos

Abstract

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. (AU)

• FAPESP's process: 14/03209-0 - IGF-1, leptin, insulin and GH levels in Nellore cattle and relation with reproduction efficiency
• Grantee: Rogério Fonseca Guimarães Peres
• Support Opportunities: Scholarships in Brazil - Doctorate