The experiment was conducted to investigate the effects of dietary crude protein (CP) and calcium (Ca) levels during the overall breeding period on reproductive performance and blood biochemical indices of breeder roosters. A total of 135 new Yangzhou breeder roosters at 21 weeks of age were randomly divided into
9 groups with 3 replicates each and 5 roosters each replicate. The roosters were fed with 9 different diets designed by a 2×3 factorial arrangement with three crude protein levels (17%, 14% and 11%) and three calcium levels (3.3%, 2.3% and 1.3%) and the same other nutrition levels during the overall breeding period. The results showed as follows: 1） the roosters in 11% CP+1.3% Ca group had the maximum density of sperm （P>0.05）, and the number of available sperm was the largest, which significantly higher than that in 11% CP+2.3% Ca group, 17% CP+2.3% Ca group and 17% CP+3.3% Ca group （P<0.05）. The roosters in 14% CP+3.3% Ca group had the largest amount of semen, which significantly higher than that in 17% CP+2.3% Ca group and 17% CP+3.3% Ca group （P<0.05）, but not significantly higher than that in the others （P>0.05）. The roosters in 11% CP+1.3% Ca group and 14% CP group (with 1.3%, 2.3% and 3.3% calcium) had the higher sperm motility, there was no significant difference among them （P>0.05）, but which significantly higher than that in 11% CP+2.3% Ca group, 11% CP+3.3% Ca group and 17% CP+2.3% Ca group （P<0.05 or P<0.01）. 2） The roosters in 17% CP+2.3% Ca group had the highest content of total protein in serum, which significantly higher than that in the other groups except for 11% CP+1.3% Ca group and 11% CP+2.3% Ca group （P<0.05 or P<0.01）. The roosters in 11% CP+1.3% Ca group had the highest content of albumin in serum, which significantly higher than that in 14% CP+2.3% Ca group （P<0.05）. The content of globulin in serum of roosters in 17% CP+2.3% Ca group was the highest, and significantly higher than that in 11% CP+3.3% Ca group and 17% CP groups （P<0.05 or P<0.01）, but not significantly higher than that in the others （P>0.05）. The activity of glutamic-oxaloacetic transaminase in serum of roosters in 11% CP+1.3% Ca group, 14% CP+3.3% Ca group and 17% CP+2.3% Ca group was higher, and significantly higher than that in 11% CP+3.3% Ca group, 14% CP+1.3% Ca group and 14% CP+2.3% Ca group （P<0.05 or P<0.01）. The uric acid content in serum of roosters in 11% CP groups, 14% CP+1.3% Ca group and 14% CP+2.3% Ca group was lower, and significantly lower than that in the others （P<0.05 or P<0.01）. The roosters in 11% CP+3.3% Ca group had the lowest content of ureal nitrogen in serum, which significantly lower than that in 17% CP+3.3% Ca group （P<0.05）, but not significantly lower than that in the others （P>0.05）. The roosters in 17% CP+3.3% Ca group had the lowest content of triglyceride in serum （P<0.05）, which significantly lower than that in the other groups except for 14% CP+1.3% Ca group （P<0.05 or P<0.01）, but there were no significant differences among the other groups （P>0.05）. 3） The roosters in 14% CP+3.3% Ca group and 17% CP+3.3% Ca group had the lower content of T3 in plasma, which significantly lower than that in 14% CP+1.3% Ca group and 14% CP+2.3% Ca group （P<0.05）. The roosters in 11% CP+1.3% Ca group, 14% CP+2.3% Ca group, 17% CP+2.3% Ca group and 17% CP+3.3% Ca group had the higher content of T4 in plasma, which significantly higher than that in the others （P<0.05 or P<0.01）. The roosters in 17% CP+3.3% Ca group had the highest content of corticoids, which significantly higher than that in 17% CP+1.3% Ca group （P<0.01）, but not significantly higher than that in 11% CP groups （P>0.05）. In general, the roosters fed the diet with low crude protein and calcium levels can achieve better fertility and higher economic efficiency than that fed the diet with high crude protein and calcium levels.［Chinese Journal of Animal Nutrition, 2011, 23（8）：1280 -1288］