Comparative assessment of semen quality parameters of Dzhalginsky Merino and Russian Meat Merino rams depending on the season
Many breeds of sheep show pronounced seasonality in reproduction. The aim of the study was to study quantitative and qualitative characteristics of semen taken from Dzhalginsky Merino (DzM) and Russian Meat Merino (RMM) rams in different seasons of the year. Semen samples were taken from five rams of each breed weekly for 12 months using an artificial vagina. The study results showed significant (P<0.05) seasonal variations in semen concentration and survival. It was found that the highest semen quality was obtained in autumn, the lowest possible in spring (semen volume: 1.41 ml in DzM and 1.25 ml in RMM vs. 0.96 ml in DzM and 0.79 ml in RMM; concentration: 3.61 billion/ml in JM and 3.35 billion/ml in RMM vs. 2.66 billion/ml in DzM and 2.33 billion/ml in RMM; motility 9.08 points in DzM and 8.57 points in RMM vs. 7.42 points in DzM and 6.45 points in RMM). The estimation of semen motility after cryopreservation showed a 50% decrease on average as compared to fresh semen. Despite the high variability of most semen indices of both breeds, the conclusion was made that it is possible to use rams of Dzhalginsky Merino and Russian Meat Merino in autumn-winter and summer months. However, the revealed differences between the studied indicators within each breed indicate the need to select the producing rams based on their individual evaluation.