EFFECT OF SEASON ON THE FREEZABILITY OF BOER GOAT SEMEN IN THE NORTHERN TEMPERATE ZONE

The influence of season (spring, summer, autumn and winter) on pre- an d post-freezing percentage of motile spermatozoa and percentage of liv e spermatozoa in Beer breed goat semen was studied between February 1, 1989, and January 1, 1990. Of the available 195 ejaculates collected from 6 healthy sexually mature Beer goat bucks, 177 had a mass activit y greater than 3 (0 to 5 scale) and were included in the experiment. T he remaining 18 ejaculates were too small or of low quality and were d iscarded. Semen was extended in Tris-egg yolk-glycerol-fructose extend er, frozen over liquid nitrogen vapor and stored for 18 h at -196 degr ees C. Straws were thawed in water at 37 degrees C for 2 min before sp erm evaluation. The percentages of post-freezing motile and live sperm atozoa were at a maximum in February (47 +/- 3 and 51 +/- 5%) and at a minimum in May (23 +/- 3 and 27 +/- 4%). Semen frozen in winter had a higher (P < 0.05) proportion of motile (45 +/- 3%) and live spermatoz oa (49 +/- 3%) than semen frozen in spring (29 +/- 2 and 32 +/- 3%). B etween the summer and the autumn season there was no difference (P > 0 .05) with respect to the above mentioned post-freezing semen character istics.