Lower methionine/cystine ratio in low-protein diet improves animal reproductive performance by modulating methionine cycle.

Overall, the present study showed that a dietary lower Met:Cys ratio in a low-protein diet had a positive influence on the reproductive performance of male animal through obviously improving sperm quality and antioxidant capacity, and inhibiting apoptosis. And the study provided new pieces of evidence to re-evaluate the role of precise sulfur amino acid nutrition in a low-protein diet.