Effect of myostatin genotype in Preta cattle breed on productive traits

Abstract

Preta is an autochthonous Portuguese cattle breed produced essentially on an extensive basis. The appearance of the mutation in the myostatin gene, allowed this breed to be exploited in pure breeding, given the substantial increase in productivity.

In this study, information was collected at the National Testing Center of the Associação de Criadores de Bovinos da Raça Preta to compare animals of different genotypes (homozygous and heterozygous) for this mutation. Productive parameters (average daily gain – GMD – and feed conversion index – IC) were studied to understand the benefits associated with the presence of the mutation.

Data from 333 animals from 14 farms (2002 to 2019) were compiled and analyzed. An analysis of variance was developed where the model considered as fixed effects the breeder, the performance test and the initial weight.

Least squares means were estimated where heterozygous animals for the mutation showed better productive performance (GMD - 1.167±0.032 kg/day; IC - 5.189±0.168). The second-best result was found for animals with wild genotype (GMD - 1.161±0.034 kg/day; IC - 5.380±0.177). The homozygous had the worst productive performance (GMD - 1.024±0.056 kg/day; IC - 5.804±0.269). The results obtained suggest that the productive system in extensive regime may not be the most suitable for homozygous animals.

The analysis model was significant, with considerable differences between the studied genotypes, for GMD and IC, with all fixed effects considered equally significant. This study intended to provide more information to breeders and to contribute to the implementation and adaptation of selection strategies more suited to the production system.