Association of GH and IGF-1 polymorphisms with growth traits in a synthetic beef cattle breed

Andréa Pozzi Pereira,Luciana Correia De Almeida Regitano,Maurício Mello De Alencar,Henrique Nunes De Oliveira

doi:10.1590/s1415-47572005000200009

Abstract

The Canchim beef cattle (5/8 Charolais + 3/8 Zebu) has been selected for meat production in Brazil since late 1950. In the present work the effects of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) polymorphisms were investigated in 688 animals born between 1998 and 2000. These animals belonged to two genetic groups, i.e., traditional and new lineages. Genotype effects on expected breeding values for birth weight (BW), weaning weight (WW) and yearling weight (YW) were investigated by the least square method. Significant effects were found for GH genotype on YW (p < 0.05), with positive effects associated with the LV (leucine/valine) genotype. For IGF-1 genotypes, significant effects were found on BW (p < 0.01) and YW (p < 0.01). Average substitution effects for IGF-1 alleles estimated by regression analysis suggested a positive effect of the IGF-1 225 bp allele on BW and of the 229 bp allele on YW.

Highlights

Crosses among breeds allow the formation of new breeds, selected for favorable traits including adaptation to the environment
The higher expected breeding value means found for genetic group 2 (GG2) were expected, since genetic group 1 (GG1) was obtained by crosses between Charolais and Bos indicus breeds in the early 1950s, and the first crosses for the obtention of GG2 were started only in 1984
The superiority of the LV growth hormone genotype compared to LL with regard to yearling weight (YW) is in agreement with earlier suggestions of selection favoring the V allele over

Summary

Introduction

Crosses among breeds allow the formation of new breeds, selected for favorable traits including adaptation to the environment. With a 5/8 Charolais + 3/8 Zebu genetic composition, have been selected for meat production traits since 1950. Localization of QTLs (Quantitative Trait Loci) can be done by linkage disequilibrium analysis or by candidate gene approach. Candidate genes have known biological functions related to the development or physiology of an important trait (Rothschild et al, 1997). Such genes can encode structural proteins or a member in a regulatory or biochemical pathway affecting the expression of the trait (Bryne and McMullen, 1996) and can be tested as putative QTLs (Yao et al, 1996)

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Conclusion