Semen quality analysis of the Airshire bulls in relation to the AH1 fertility haplotype

Abstract

The results of the studies (2019-2021) of increased incidence of genetic mutations, such as fertility haplotypes, in the population that result in lower reproductive rates in dairy cattle are presented. Semen quality of the Ayrshire breed bulls was evaluated for motility and morphological indices due to rs475678587 in the UBE3B gene locus associated with the AH1 fertility haplotype. Semen samples (n = 14) were obtained from the Center of Collective Use "Genetic Semen Collection of Domestic and Foreign Cattle Breeds" of the All-Russian Research Institute of Farm Animal Genetics and Breeding (ARRIFAGB) and belonged to the animals born in 2014 and older (average age of bulls was 6-15 years). Genotyping for rs475678587 of the UBE3B gene was performed by Sanger sequencing. Animals with the heterozygous CT genotype were defined as carriers of the AH1 haplotype (AH1-C), and those with the homozygous CC genotype were defined as free of the AH1 haplotype (AH1-F). Frozen-thawed semen was evaluated according to the following parameters: total and progressive motility, percentage of normal spermatozoa. Morphological indices of sperm quality were assessed after differential staining of cellular elements of spermatozoa using a commercial kit "Diakhim-Diff Quick" (ABRIS+ scientific and production company) in sperm smears. The following indicators were taken into account: acrosomal abnormalities, abnormalities in the head, tail, and neck of the spermatozoon. Data on the indicators of native semen (motility, concentration), obtained immediately after collection, were received from the archive of the technical service of the breeding enterprise. The results of the studies have shown that according to physiological and morphological indices the semen obtained from the bulls carrying the haplotype AN1 did not differ significantly from those of the bulls free of the mutation. In terms of total motility, the semen of the haplotype fertility carrier bulls was almost 2% higher than that of the haplotype free bulls. It can be noted that the haplotype carriers of fertility bulls were generally characterized by good sperm fertility indices.