Estimation of the associations between GH and DGAT1 genes and growth traits by using decision tree in Awassi sheep

GH and DGAT1 are candidate genes associated with growth traits in sheep breeds. This study aims to determine the association between growth traits and GH and DGAT1 gene polymorphism using three statistical methods in Awassi sheep. The polymorphism was detected by the PCR-RFLP method. Three genotypes (AA, AB and BB) were observed for GH gene locus with allele and genotype frequency 0.70(A) and 0.30(B); 0.60(AA), 0.20(AB) and 0.20(BB). Three genotypes (CC, CT and TT) were found for DGAT1 gene locus with allele and genotype frequency 0.58(C) and 0.42(T); 0.47(CC), 0.23(CT) and 0.30(TT). The genes were in agreement with Hardy-Weinberg equilibrium (p > 0.05). CHAID, CRT and GLM were used to identify the association between growth traits and gene polymorphism. The results showed an association between GH locus and body weight and tail length. Also, found an association between DGAT1 locus and tail length. The three methods showed similar results in determining the association between genes and growth traits. Thus, the CHAID and CRT methods can evaluate the association between genes and growth traits.