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.

Sheep are among the earliest species domesticated by humans, with archeological findings indicating their domestication occurred approximately 11,000 years ago in the Fertile Crescent, a region in ...

GH gene is one of the important genes that affect the productive and physiological traits in livestock. This study aimed to use a meta-analysis to determine the association of the GH gene with growth traits in cattle. Four different genetic models were used: dominant LL + LV versus VV, recessive LL versus LV + VV, complete over dominant LL+VV vs. LV and co-dominant LL vs. LV, LL vs. VV and LV vs. VV. The random-effect model was used in data analysis based on I2. Meta-analysis showed an effect of GH genotypes on the birth weight (BW) under the recessive (p<0.05) and complete over dominant (p0.05) was found under the dominant model. In terms of co-dominant model, the GH polymorphism showed a significant association with BW (SMD = 0.359, 95% CI = 0.119 to 0.599, p = 0.003) under LL vs. LV genotype combination patterns. No association was found between GH polymorphism and BW under LL vs. VV genotype combination. The results showed that the LL genotype had a significant effect on BW traits from LV and VV genotypes when comparing the models. The results showed an effect of the GH on ADG under four genetic models (p<0.05).

This study aims to find the association between MYLK4 gene polymorphism and growth traits at different ages, such as birth, 3rd-month, 6th-month and 12th-month ages in Anatolian black cattle. PCR-RFLP method was used to detect the polymorphism for MYLK4 gene in at G61595A locus. Allele and genotype frequencies were A: 0.34, G: 0.66 and AA: 0.17, AG: 0.34 and GG: 0.49. The chi-square χ ² test showed an agreement to Hardy–Weinberg equilibrium (p > .01). GLM and RRM models were used to estimate the association between MYLK4 gene polymorphism and growth traits. The results of the statistical analysis indicated an association between MYLK4 gene polymorphism and growth traits at different stage ages in Anatolian black cattle. Therefore, the G61595A mutation of MYLK4 gene can be used as a genetic marker for the selection of growth and development traits in the cattle breeding programs.