Estimates of genetic parameters for reproductive traits in Brahman cattle breed

• Grant number: 15/12283-2
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: August 01, 2015
• End date: January 31, 2016
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Ricardo da Fonseca
• Grantee: Ricardo da Fonseca
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

This study was designed to estimate genetic parameters for the following traits of Brahman cattle in Brazil: age at first calving (AFC), calving interval (CI), rebreeding (REB), and stayability (STAY). For REB, the value 1 was assigned to heifers that rebred and calved after first calving and the value 0 was assigned to heifers that failed to rebreed after first calving. Likewise, for STAY, the value 1 was assigned to cows that calved at least 3 times by the time they reach 6 years of age; otherwise the value 0 was assigned. A bivariate analysis was used to estimate covariance components by using linear animal model for CI and AFC and threshold animal model for REB and STAY. The mean h2 were 0.10, 0.02, 0.22, and 0.10 for AFC, CI, REB, and STAY, respectively. The genetic correlations were -0.13 between AFC and CI, -0.35 between AFC and REB, -0.57 between AFC and STAY, and 0.32 between REB and STAY, which reveal that cows that remain productive for longer periods in the herd also start breeding younger and present greater chances to REB. The selection of Brahman cattle for reproductive traits, such as AFC, CI, REB, and STAY, render low magnitude and long-term responses. (AU)