South African Journal of Animal Science
On-line version ISSN 2221-4062
Print version ISSN 0375-1589
The aim of this study was to test the effect of oestradiol-17β (E2) on the motility, viability and the acrosomal status of bull sperm in vitro. Pooled semen from Holstein bulls were incubated in the presence of 2, 4, and 8 µg E2/mL for 24 h. Semen was also incubated in media without E2. During the incubation, the number of motile, viable sperm and the number of sperm possessing lost/damaged acrosomes, cytoplasmic droplets and coiled tails were counted at 0, 4, 18 and 24 h of incubation. Addition of 2 µg E2/mL at 18 h of incubation increased the total motility over the control. The number of forward progressing sperm was increased by the supplementation of 2 and 8 µg E2/mL over the control group at the 4 h incubation. Lower doses of E2 (2 and 4 µg/mL) did not affect viability of sperm, but a high dose of E2 (8 µg/mL) caused reductions in viability at 4 and 24 h of incubation. The number of sperm cells with lost acrosomes was significantly high in control group at 24 h of incubation. The number of sperm cells possessing proximal and distal cytoplasmic droplets and the number of sperm cells bearing coiled tails were not altered by any of the treatments. A small dose of E2 (2 µg/mL) had a beneficial effect on the motility and acrosome integrity of bull sperm in vitro. Higher dose of E2 (8 µg/mL) had a detrimental effect on viability.
Keywords : Bovine males; estradiol; acrosome; motility; spermatozoa; in vitro incubation.