We have reported that artificial insemination (AI) with frozen-thawed boar semen supplemented with caffeine increased the
number of uterine sperm by inhibiting the migration of polymorphonuclear leukocytes (PMNs) into the uterine lumen, thereby
improving the fertility of gilts and sows. The objective of the present study was to examine the effects of the addition of
the antioxidant beta-mercaptoethanol (bME) and caffeine to the thawing solution on the function of frozen-thawed sperm, on the
phagocytic activity of PMNs for sperm, and on the fertility of sows after AI. When frozen-thawed sperm were cultured in the
presence of 25 or 50 M bME, sperm capacitation and spontaneous acrosome reactions were inhibited (P 0.01). There was no
effect of bME on phagocytic activity of PMNs for sperm in vitro. When hormonally treated (400 IU of equine chorionic
gonadotropin 200 IU of human chorionic gonadotropin) weaned sows experienced a single intrauterine insemination with
frozen-thawed sperm (25 108 sperm per 50 ml dose) 40 h after subsequent hCG administration, pregnancy and farrowing rates
were unaffected by the addition of 50 M bME (pregnancy rate, 20 vs 21% in controls; farrowing rate, 20 vs 21%; n 15 and
14, respectively). However, litter size tended to be higher than in the presence of 50 M bME compared to its absence (10.0
1.0 vs 5.7 1.5, respectively; P 0.07). Thus, the addition of bME to the thawing solution containing caffeine could be of benefit
for improving the function of frozen-thawed sperm without influencing the phagocytic activity of PMNs for sperm. Although there
were no statistically significant effects of bME on pregnancy or farrowing rates, the litter size tended to be higher in the sows
subjected to a fixed-time single AI treatment with synchronized ovulation.
© 2012 Elsevier Inc. All rights reserved.