The potential influence of plant-based feed supplements on sperm quantity and quality in livestock: a review

The reproductive performance of male livestock is of economic importance, and improving semen quantity and quality, especially for artificial insemination, additionally helps to avoid the loss of valuable genotypes. The review focuses on the impact of oxidative stress on sperm production and quality in livestock, and the potential role of plant based anti-oxidants to control this impact. From scientific reports dealing with livestock, the paper compiles evidence on effective dietary measures affecting sperm production and quality. Where little or no data are available on livestock, it refers to sources regarding other mammals, including man. The review concentrates on the use of distinct plants as feed supplements rather than on ways to treat deficiencies and imbalances in energy or macro- and micronutrients. Feeding of maca (Lepidium meyenii) and khat (Catha edulis) has been shown to positively affect sperm production and quality in animals. Some evidence points to favourable effects of leucaena (Leucaena leucocephala and Leucaena pallida), sesbania (Sesbania sesban), pomegranate (Punica granatum), tomato (Solanum lycopersicum) and amaranth (Amaranthus hypochondriacus) as well, but studies are either superficial or results are partially contradictory. Finally, the review considers the potential usefulness of medicinal herbs. The list of such plants includes Chinese herbs such as Lycium barbarum, Astralagus membranaceus, Acanthopanacis senticosi, Magnolia officinalis, Cornus officinalis and Psoralea corylifolia and the Indonesian plant Eurycoma longifolia. European candidate plants are Tribulus terrestris and Pendulum murex. Future research should include the screening of other plants, concentrating on the large number of plants rich in metabolites because of their presumed effectiveness. The modes of action often require clarification for the plants with demonstrated effects.