Molecular markers of growth hormone and insulin-like growth factor-I as predictors of productive performance in Holstein Friesian under pastoral condition

Abstract

The use of DNA molecular markers for genetic improvement has substantially increased in the dairy industry worldwide and is increasing in Uruguay. Nevertheless, there are no reports regarding the validation of these markers under grazing conditions. In this study, genotype frequencies of growth hormone (GH) and insulin-like growth factor-I (IGF-I) and its association with productive parameters (milk production and composition) under grazing conditions were investigated. Holstein cows (n=161) of one, two, and three lactations from two  comercial farms were genotyped for GH and IGF-I using PCRRFLP. Frequency for L allele of GH gene was 0.84 and for allele V was 0.16. For IGF-I gene frequencies were 0.60 and 0.40 for A and B alleles, respectively. Variants of GH and IGFI were not associated with any variable of milk production or composition, in contrast to international studies, suggesting that molecular markers should be validated in the production system in which they will be utilized.