12 crossbreed boars received 4 rations containing varying levels of lysine and DL-methionine. The results obtained from this study are summarized as follows ; 1. Semen volume, total sperm number of the treatment B, C and D were increased significantly (p<0.05) as compared with the treatment A but abnormal sperm percent of treatment B and C was decreased significantly (p<0.05) as compared with A. Sperm number and sperm mortility were not different from treatments. 2. Amino acids contents of sperm plasma were not different from treatments.