Estimates of genetic parameters and genetic trends for reproductive traits and weaning weight in Tabapuã cattle

• Grant number: 15/20905-3
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: November 01, 2015
• End date: April 30, 2016
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Danísio Prado Munari
• Grantee: Danísio Prado Munari
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The Tabapuã breed is a beef cattle Brazilian breed known for its sexual precocity and desirable characteristics for tropical conditions. However, this is a newly formed breed and few studies have been conducted regarding genetic parameters and genetic trends for its reproductive traits. The objective of the present study was to estimate the genetic parameters, genetic trends and relative selection efficiency for weaning weight adjusted to 210 days of age (W210), age at first calving (AFC), average calving interval (ACI), first calving interval (CI1) and accumulated productivity (ACP) among Tabapuã beef cattle. Pedigree data on 15,241 Tabapuã animals, born between 1958 and 2011, and phenotype records from 7,340 cows, born between 1970 and 2011, were supplied by the National Association of Breeders and Researchers (Associação Nacional de Criadores e Pesquisadores, ANCP). Analysis through the least squares method assisted in defining the fixed effects that were considered within the models. The estimates for the genetic parameters were obtained through the REML, using a multi-trait animal model. The likelihood ratio test applied for W210 resulted significant (P < 0.05) for the inclusion of maternal additive genetic and permanent environmental effects in the model. Genetic trends were calculated through linear regression of the estimated breeding values of the animals, according to the year of birth. The heritability estimates obtained ranged from 0.04 ± 0.03 for CI1 to 0.25 ± 0.05 to W210. The genetic correlations ranged from 0.004 ± 0.19 for W210-AFC and 0.93 ± 0.12 for ACI-CI1. The genetic trend was significant (P < 0.05) and favorable for CI1 and the maternal genetic effect of W210; significant (P < 0.05) and unfavorable for AFC, ACI and ACP. The ACP could be used in the selection index to assist the breeding goal of improve productive and reproductive performance. The genetic trends indicated small and unfavorable genetic changes for AFC, ACI and ACP in the light of the recent implementation of a genetic breeding program for this breed. (AU)