Breed and stallion effects on frozen-thawed semen in warmblood, light and quarter horses.

The study explores the impact of various factors on the quality of fresh and frozen-thawed semen in different horse breeds. The research indicates that breed, age, and time of year all significantly affect semen characteristics such as sperm concentration, total sperm count, and motility. Notably, the DNA fragmentation index varied widely amongst stallions.

Methodology

• The study used a total of 4,681 reports on semen traits of 121 stallions. These stallions represented Arabian, Thoroughbred, Quarter Horse, and four warmblood breeds.
• All horses in the study were used for artificial insemination at the Lower Saxon National Stud Celle.
• The study focused on several semen traits, including gel-free volume, sperm concentration, total number of sperm, total number of motile sperm in fresh semen, frozen-thawed semen progressive motility, DNA fragmentation index, and non-viable sperm.
• A linear mixed model procedure was used to analyze the effects of month, year, age, breed, and stallions on the aforementioned traits.

Findings

• The breed of the horse was found to significantly affect sperm concentration, total sperm count, total motile sperm count, and DNA fragmentation index.
• Stallions belonging to the Hanoverian breed had higher concentrations of sperm, higher total sperm counts, and a higher number of motile sperm in fresh semen compared to other breeds.
• The Thoroughbred breed, however, had a significantly higher DNA fragmentation index.
• Stallions aged 2-6 years had lower sperm concentration, total sperm count, and total motile sperm count, as well as lower progressively motile sperm after thawing, compared to other age groups.
• The study also found that the month of semen collection significantly affected all semen traits, except for progressively motile sperm after thawing.
• Considerable between-stallion variability was observed, with inter-stallion variance accounting for 27-71% of the total variance of semen quality traits.
• The DNA fragmentation index showed the greatest inter-individual variability among stallions.

Implications

• The results of the study are relevant to both horse breeders and veterinary professionals, as they provide insight on the impact of various factors on horse semen quality.
• This could potentially aid in optimizing breeding strategies, improving the success rate of artificial insemination procedures, and contributing to overall horse population management.
• The significant impact of stallion age also suggests that targeted semen collection strategies could potentially enhance breeding success.