Polymorphisms in CAST genes and their association with feed conversion ratio in Latvian Dark-Head sheep

In animal husbandry, feed efficiency is a crucial economic trait. The feed conversion ratio (FCR) is a traditional metric for assessing feed efficiency, defined as the ratio of dry matter intake to average daily gain. Improving FCR parameter in breeding is highly important for sheep production. Sire rams with better FCR indicators produce offspring with higher value of this indicator.

With the rapid development of science and technology (DNA analysis), more opportunities for breeding using genetic markers associated with various productive traits exist. Calpastatin (CAST) plays a key role in skeletal muscle development and is involved in protein metabolism, muscle growth and development, and fat deposition.

This study aimed to analyze CAST gene polymorphisms and their relationship with FCR in the Latvian Dark-head (LT; Latvijas tumšgalve) breed. After control fattening, blood samples were collected from 48 offspring of LT sires for DNA isolation. Exons of CAST gene and flanking intron regions were sequenced using NGS technology. The CAST gene has been sequenced in LT lambs for the first time; 43 polymorphisms with known ID numbers were identified.  From all loci, 18 were rear: minor alleles less than 10%. In the case of SNPs: rs408766737, FCR values of lambs homozygous for the rear allele were statistically significantly lower than the rest of the animals from the experimental cohort. Therefore, CAST gene SNPs have the potential to be molecular markers to predict the FCR value.