The genetic basis of the sperm quality of stallions

One of the important factors affecting the reproductive function is the genotype of the animal. The method of genomic selection is based on the use of polymorphic single nucleotide substitutions (SNP) as markers  for determining the value of the genotype of an animal or plant. The formation and functioning  of  the  reproductive  system  of  animals occurs as a result of the coordinated interaction of a wide range of genes.  The search for genomic  associations  of  GWAS  (Genome-Wide Association Studies) with signs of fertility will allow further selection of animals based  on  these  indicators  at  the  genomic level. Sperm was obtained with the help of mares in hunting and on a phantom using an artificial  Hannover  vagina  (Minitube,  Germany). The sperm of each stallion was collected at least three times. The semen quality of 96 stallions of different breeds (Arabian, Akhal-Teke, Trakenen, thoroughbred horse, Oryol  trotter,  French  trotter,  Soviet  heavy horse, Shetland pony, Welsh pony, horses of different breeds) was analyzed. High variability  of  sperm  quality  indicators  was  revealed.  For  example,  the  concentration  of sperm in the ejaculate varied from 59 to 514 million /ml, progressive mobility from 20 to 87%, and the number of cells without damage from 21.6 to 95.6%. Such variability of the studied features makes it possible to assume that their formation in the process of ontogenesis  occurs  under  the  influence  of genetic factors. The GWAS analysis of ejaculate volume, concentration and motility of stallion  sperm  revealed  potential  candidate genes associated with these indicators. The associations identified in our study are promising candidates for further identification of the  biological  mechanisms  underlying  the quality of stallion sperm.