GENETIC EVALUATIONS: ZEBU BREEDS

Abstract

Since its foundation in 1966, the Mexican Association of Zebu Breeders (AMCC), marked as one of its main objectives the genetic improvement of the Zebu breeds: Brahman (Br), Guzerat (Gu), Gyr (Gy), Indubrasil (In), Nellore (Ne) and Sardo Negro (Sn). To carry out evaluations, it was necessary to have databases with 473436, 13812, 98385, 174752, 105641 and 37603 productive records for Br, Gu, Gy, In, Ne and Sn breeds, respectively. The AMCC established the Control Program of Ponderal Development (PCDP), which includes four control ages: weight at birth (BW), weight at weaning (WW), weight per year (WY) and weight at 550 days (W550). The final tests were done through and univariate animal model, using the maximum restricted analyzes that considered the vector of observations for each of the weights, the vector of the fixed effects of breeder subclasses and contemporary group (year and season calving – sex – feed regimen), age of the cow at birth (linear and quadratic) and the vector of random effects (animal - sire - cow). With these analyzes the expected progeny differences (EPD) and accuracies were obtained. The EPD is an essential tool for the selection of the future parents of each herd by allowing an animal to be placed with in a classification, so its use is recommended when the breeders are acquired. It is concluded that the estimation of the EPD will reflect their advantages to the extent that they are used by farmers.