عنوان مقاله [English]
This study aimed to investigate te effect of different ratios of carbon to nitrogen on growth factors, carcass chemical composition and immune system of Chinese carps (Silver carp, Bighead, Common carp and Grass carp). For this purpose, a total of thirty thousand juveniles of four species with a ratio (80-5-10-5%) with an average weight of 120 g were obtained and for 2 months in 4 treatments with C/N conditions, including treatment 1 (5-8), treatment 2 (8-12), treatment 3 (12-15) treatment 4 (control group) were reared and fed by adding sugar beet molasses carbon source. The reason for choosing the range in carbon to nitrogen ratios was due to the large area of the experimental units (two-hectare ponds). Increasing the different ratios of carbon to nitrogen significantly increased the final weight and decreased the feed conversion ratio in common carp and silver carp in treatment 3 compared to the control group. The highest percentage of the protein and fat measured in the carcasses of all four fish species belonged to treatments, which showed a significantly increase compared to the control group. The moisture content, carcass ash percentage and survival percentage did not show a significant difference between treatments. The alkaline phosphatase in all treatments was significantly increased and the spartate aminotransferase and alanine-aminotransferase in all experimental treatments were significantly reduced except grass carp which significantly increased the level of alanine enzyme.