Stallion semen experiences oxidative stress during cooling and transport, and is consequently damaged by reactive oxygen species. Two different approaches have been investigated to enhance the intrinsic antioxidant defense mechanisms against oxidative stress in liquid-preserved semen.
First, a dietary antioxidant supplementation to improve antioxidant status in tissue, seminal plasma and spermatozoa was tested. Second, the combined addition of three enzymatic antioxidants to semen extender in order to increase the antioxidant status of seminal plasma was evaluated.
In the first experiment, the effect of dietary supplementation with Lepidium meyenii (Maca) on fresh and chilled stallion semen characteristics were evaluated. Maca is a traditional Andean crop used as a nutraceutical for its fertility-enhancing properties which is linked with its antioxidant activity. The diet of five stallions was supplemented daily with 20 mg of Maca powder for a total of 60 days. A control group of another five stallions received the same diet without Maca. Semen was collected once before the administration of Maca (D0), twice during the administration at 30 and 60 days (D30-D60), and finally twice at 30 and 60 days after the end of the administration (D90-D120). Ejaculates were processed for cooled shipping at 5°C and evaluated in the laboratory for total and progressive motility, acrosome integrity and lipid peroxidation after collection and after 24 hours, 48 hours, and 72 hours storage, respectively. Dietary supplementation with Maca significantly improved sperm concentration and total sperm (p