Abstract
In Kazakhstan, meat–fat-tailed sheep breeding is crucial for breed development and high-quality mutton production. Understanding variations in candidate genes may improve selection for meat quality and growth traits. Therefore, this study aimed to investigate the relative mRNA expression levels of the DGAT1, CAST, IGF-1, POU1F1 genes using qRT-PCR in tissues from three 12-month-old male Degeres sheep, identify SNP variations by PCR and Sanger sequencing, and assess their associations with growth traits in 18-month-old female Degeres sheep (n = 380). Relative mRNA expression revealed tissue-specific expression patterns of the studied genes, with DGAT1 showing the highest expression in abdominal fat (p < 0.001), CAST in the abomasum (p < 0.01), IGF-1 in the liver (p < 0.001), and POU1F1 in the testis (p < 0.05). The findings uncovered a previously reported synonymous SNP (c.1461 C > T) in the DGAT1 gene and polymorphism information content (PIC) exhibited low polymorphism. Moreover, the identified SNP deviated from Hardy–Weinberg equilibrium (HWE) and was significantly associated with chest width (p = 0.001), with the “TT” genotype exhibiting greater chest width. Therefore, further studies with larger sample sizes are required to validate its potential use in marker-assisted selection (MAS) to optimize sheep breeding.