Abstract:
We investigated the supplementation effects of Acacia mearnsii tannin extract (TE) and
encapsulated tannin extract (ETE) on reproductive performance and oxidative status of South African
Mutton Merino rams. We also observed the season effect on the testicular measurements. Thirty
rams were divided into five groups: 0.0 g TE (control), 1.5 g TE, 3 g TE, 1.5 g ETE, and 3 g ETE
supplemented daily for 16 weeks transiting from autumn to winter. Bodyweight and testicular
measurements were recorded biweekly. Semen and blood samples were collected weekly during
the last five weeks of supplementation. Results showed that the increase in the ETE from 1.5 to
3 g increased the testicular length and sperm concentration, as well as decreased the percentages
of low and non-progressive spermatozoa (p < 0.05). Simultaneously, the increase in the TE from
1.5 to 3 g decreased semen volume and elevated the percentage of abnormal sperm (p < 0.05). The
results suggest that the encapsulation of TE affords the maximum benefit of the TE on the sperm
quality. Treatments did not affect the hormonal and oxidative status. Testicular measurements
were significantly higher in autumn compared to winter. The plasma level of cortisol significantly
correlates negatively with sperm motility, viability, and acrosome integrity.
