Improvement of the method of preparation of ram-sires for the semen col-lection
Abstract
The results of studies on the semen production of ram-sires of three European meat breeds, such as texel, oxford down and Vvalais blacknose in the process of preparing for a breeding season or taking semen on an artificial vagina for further use for deep freezing, are presented. During the preparatory period, from each group of rams, 120 ejaculates were obtained, 12 ejaculates in the first and second subperiods, 18 ejaculates in the third and fourth and 60 ejaculates in the fifth subperiod. Differences in the semen production performance of the breeders of the studied breeds were determined. At the end of the preparatory period, the volume of the ejaculate of the rams of the oxford down breed was greater than that of texel by 34.8%, of the valais blacknose sheeps – by 53.1%. When comparing the volume of the ejaculate of the rams of the breed of texel and valais blacknose sheeps, the latter was lower by 12.0%. The concentration of semen in the ejaculate was the highest in the Valais rams and amounted to 3.24 billion/ml, which is 3.9% higher than the oxford down rams, and 14.9% is the texel breed. According to the activity of fresh semen, the difference between the breeds was insignificant and ranged from 2.4 to 4.3%. However, the activity of the frozen-thawed semen varied from 6.4% to 14.0%, the highest among the breeders of the oxford down ‒ 3.65 points, the lowest ‒ 3.20 points in rams of the Valais Blacknose breeds. A slight 2.2 – 4.4% deviation between breeds was noted for the resistance of semen to cryopreservation. The smallest number of cryopreserved semen with acrosome damaged in oxford down breeders was found to be 39.14%, which is 3.5% less than that of texel sheep breed and 6.7% more than that of valais blacknose breed breeders. The conducted researches have experimentally confirmed that indicators of semen productivity of ram-sires are improved in accordance with the term of their preparation. Therefore, to train rams to give semen to artificial vagina before the beginning of the steaming season, or to obtain it for cryopreservation, followed by artificial insemination of sheep, is required after careful preparation of the rams for 50‒60 days, with the provision of optimal conditions of keeping and feeding. The main studied parameters of sperm production of ram-sires in the preparatory period, significantly higher values of volume of ejaculate, activity of fresh and preserved semen, their resistance to freezing and the preservation of acrosomes in the breeders of the oxford don was established. The lowest studied indices were found in rams of the valais blacknose breed. Texel breeders occupy an intermediate position for the indicated indices between the studied breeds.
Keywords
