Changes in the indicators of own productivity of Holstein bulls depending on the season and age

Abstract

Abstract. Purpose of research. To estimate the impact of the season and age of the breeding bulls during the period of sperm collection on the main indicators of the own productivity of Holstein bulls. In studies of these indicators and productivity 229 bulls of Holstein breed have studied the effect of age (year of birth), season of the year, as well as the degree of influence of these factors on the value of indicators of productivity of bulls. Methods. Data on the main indicators of own productivity of breeding bulls are analyzed: the volume of ejaculate, the amount and concentration of spermatozoa in 1 ml. The research results were classified by season: winter, spring, summer, and autumn. The values of quantitative indicators of sperm production are given as deviations from the average value for the sample. Statistical analysis was performed using a boxplot diagram with average values and standard deviation (±σ) applied to it. The analysis of variance was performed using the following statistical model: yijk = µ + agej + seasonk + eijk + si. Fischer’s F-test was used to check the significance. Results. Regardless of the season, the values of the ejaculate volume and the total number of sperm in the ejaculate increase with age, and the concentration of sperm in 1 ml decreases. In the spring and summer period, 77–83 % and 66–79 % of observations had high values of the indicator volume of ejaculate and the number of spermatozoa in the ejaculate. In the spring and autumn periods, 62–64 % of observations had high values of sperm concentration in the ejaculate. The year of birth of the producer bull and the producer bull itself have a high degree of influence on the indicators of their own productivity: the volume of ejaculate – 14.94 and 18.22 %; the number of sperm in the ejaculate and their concentration – 8.53–27.88 and 4.51–15.82 %, respectively. Scientific novelty. The data obtained on the influence factors of season, age of the bull-the manufacturer’s figures for their own productivity.