DISTRIBUTION OF EJACULATES ACCORDING TO THE NUMBER OF SPERMATOZOA IN HOLSTEIN BULLS AGED 6-7
The paper highlights the results of the system analysis carried out in order to explore the primary characteristics of native seed from Holstein servicing bulls of Black-and-White breed aged 6-7 years. The analysis was carried out to rank ejaculates by the total number of spermatozoa. The experiment was carried out at OAO “Moskovskoye on pedigree activities” in 2011 - 2013. The researchers tested 5964 ejaculates, obtained from 17 bulls during three years, in relation to the season. The researchers explored the number of ejaculates (n), defect of the native sperm when taking (%), and the seasonal dynamics of the total number of sperm cells in the ejaculate. The keeping technology, feeding and maintenance, sperm collection, its assessment and cryopreservation was carried out in accordance with the requirements of the “National technology of producing and application of servicing bulls' sperm “. Ejaculates were distributed into three groups according to the total number of spermatozoa: - up to 3 billion; - 3.1 - 5.0 billion; - 5.1 billion and more. The researchers found out that the number of ejaculates of good quality selected for cryopreservation in the mature reproductive aged bulls (6 - 7 years) is 76% on average with a variability of 73-82%, depending on the season and year of maintenance. The highest number of the ejaculates of good quality was obtained in autumn and it was 82.3%, which is 7-10% higher than that in other seasons (p<0.001). The analysis of ejaculates over a three-year period showed that the first group contained the main mass of ejaculates, where the number of spermatozoa was up to 3 billion. This parameter varied within 40-48% from season to season; the researchers observed the ejaculates that have total number of spermatozoa equal to 3.1 - 5.0 billion were 28.5-33.4%, the ejaculates that have the highest number of spermatozoa (5.1 billion and more) were 23-29%.