Evaluación cualicuantitativa y congelabilidad del semen de carneros en dos temporadas en la sierra del sur del Ecuador

Abstract

The objective of this research was to evaluate the qualitative-quantitative production and the freezability of semen from rams coming from temperate regions, in two seasons (oct-nov and June-july) in the southern Ecuadorian highlands. In Ecuador, due to its geographic location, there are no variations of the photoperiod (which are the main regulators of the reproductive function of sheep in temperate regions). The study of the effect was carried out in two seasons. To characterize the performance of these males in each of these seasons, we determined first some physical characteristics that affect reproductive function (weight, body condition, testicular diameter), and quantitative (volume, concentration, total amount of spermatozoa) and qualitative seminal variables (mass motility, progressive motility, live rate, abnormal rate, membrane functionality, and freezability). A total of 36 semen samples (18 in each season) were obtained from three Corriedale rams introduced into the country in previous years. All of these, with a docile temperament, between 3 and 4 years of age, clinically healthy and under the same sanitary and management conditions. Significant statistical differences (p <0.05) were observed in body weight, body condition, and testicular diameter. The highest values were obtained in season two (june-july). Regarding the quantitative seminal variables (volume, concentration and total amount of sperm), differences were obtained between the two studied seasons, with the highest values (p <0.05) being observed in season one (oct-nov). In the qualitative variables, there were no differences observed between the two seasons. Finally, the evaluation of frozen-unfrozen semen of the two studied seasons did not show significant statistical differences. It is concluded that these males have adapted very well to the new environmental conditions. This is particularly true in qualitative seminal production that was similar in both seasons. Because of this, it would be possible to use them as breeders at any time of the year.