engleski

Association analyses of DNA polymorphisms in bovine PRL and DGAT1 genes with milk production traits in Simmental cows

Introduction: The selection of dairy cattle is orientated mostly towards the improvement of milk traits – milk yield, fat and protein yield and content. Genotyping tests give breeders the opportunity to use previously unavailable information to increase the frequency of beneficial alleles in their herds. Acyl-CoA: diacylglycerol acyl transferase 1 (DGAT1) enzyme has a role in the synthesis of triglyceride with the catalyzation of the reaction of diacylglycerol and fatty acid. Previous studies reported DGAT1 gene pleced on BTA14 as a potential candidate gene, with a nonconservative substitution of lysine by alanine (Lys232Ala) producing a major effect on milk composition and yield. Prolactin (PRL) plays an important regulatory function in mammary gland development, milk secretion, and expression of milk protein genes. PRL synonimous SNP G8398A, mapped on chromosome 23, has become a popular marker used for genetic characterization of cattle populations regarding milk composition and yield. To examine their possible applications in the genetic improvement of dairy cattle productivity, we herein investigated the effects of the DGAT1 Lys232Ala and PRL G8398A SNPs on milk, fat and protein yield, as well as fat and protein percentage in the milk Materials and methods: The 51 Simmental cows from one dairy farm were genotyped. Information about milk traits for each cow were provided by the Croatian Agrucultural Agency which is responsible for milk recording system according to ICAR rules. DNA was isolated from milk and genotyping of DGAT1 and PRL genes was performed using PCR-RFLP. Frequencies of alleles and genotypes were calculated and association analysis was performed using general linear model calculations. Results: In DGAT1 gene allele A had higher frequency (0.54), and the most common genotype was KA (0.67). There was no association found between DGAT1 gene polymorphism and milk performance traits (P>0.05). For the PRL gene, the alel G had higher frequency (0.95). The genotype AA wasn't found and the gentopye AG was found in low frequency (0.11). No significant differences were detected between the two found genotypes (P>0, 05). Conclusion: Although in most of the previous studies SNP Lys232Ala showed significant impact on fat yield and percentage, in the studied population no association was found. The prevalence of the allele G in the PRL gene could explain the lack of significant differences between two found genotypes for the examined traits (P>0.05).

DGAT1; PRL; Simmental; milk production

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