BACKGROUND AND AIM

Milk produced from Awassi sheep is of high nutritive value; its production is relatively low in Awassi sheep, so the genetic improvement programs targeted milk production and its components are of high importance, especially when using genes that have an important signal to milk traits. This study was aimed at assessing the influence of alpha S1 () and beta-casein () genes genotypes interaction on Awassi ewes milk productivity.

MATERIALS AND METHODS

A total number of 391 milk yield and its composition records (taken through five consecutive years, 2007-2011) of 167 ewes were utilized for this study. DNA samples were extracted from the ewe's blood samples, then the polymerase chain reaction products of alpha S1 () and beta-casein () genes were sequenced. The obtained sequences were analyzed; thereafter, the detected variants were tested for their possible association with milk traits.

RESULTS

The and variants allelic frequencies were 0.85 and 0.15, and 0.95 and 0.05, respectively. Lactose and solid not fat (SNF) % were associated with TC genotypes. No association was found among polymorphic genotypes with milk production, lactose, and SNF % were associated with TC genotypes. Ewes of AC genotype showed higher milk production traits, while no association was found between milk composition traits and genotypes. Nevertheless, interaction showed the highest SNF, fat percentages, and milk production.

CONCLUSION

The substantial interaction effects between genes were significantly affected the amount of milk, fat, and SNF% produced. The detected variants should be included in the breeding programs of Awassi sheep that are designed for improving their milk quantity and quality.