Effects of season and breed on sperm acrosin activity and semen quality ofboars

Acrosin activity and semen quality (sperm concentration, ejaculate volume a nd number of spermatozoa) were assessed from March 1997 to March 1998 in se men of Large White, Pietrain and Duroc x Pietrain boars. Semen quality vari ed with season, including high production of spermatozoa in autumn and wint er and low production in summer. Semen quality also differed across breeds. Acrosin activity of boar spermatozoa was not affected by breed (range 3.16 -3.32 mU/10(6) spermatozoa), but exhibited distinct seasonal changes. Month ly changes in acrosin activity were parallel to changes in number of sperm in the ejaculate from November to March. On the other hand, dramatic change s in acrosin activity between July and October (range 1.85-4.59mU/10(6) spe rmatozoa) were not paralleled by similar changes in number of ejaculated sp erm. These fluctuations in acrosin activity may reflect either changes in s perm acrosin production or disturbances to sperm membranes, probably relate d to effects of high summer temperatures during spermatogenesis. Results co nfirmed seasonal and breed-related differences in boar semen quality charac teristics. (C) 2000 Elsevier Science B.V. All rights reserved.