Optimal protein and lipid requirements of snakehead, Channa striata, during the grow-out stage

Abstract:

Channa striata is a high-value, carnivorous freshwater fish species widely farmed in the Southeast Asia. However, its basic nutrient requirements during the grow-out stage （body mass> 100 g） are largely unexplored. In this study, we first explored the optimal protein requirement of Channa striata. Six isolipidic （15%） diets with varying protein levels were formulated by adjusting the fish meal inclusion level. Fish with a mean initial body weight of 150 g were fed these experimental diets to apparent satiation twice daily for 8 weeks. Our results showed that the growth performance and feed efficiency of Channa striata improved and plateaued while the protein retention increased and then declined, as the dietary protein level increased from 36% to 51%. Using the weight gain and protein retention as response variables, the protein requirement of Channa striata was estimated to be 41.5% and 42.3%, respectively, by the regression analysis. We further explored the optimal lipid requirement of Channa striata based on the protein requirement result. Six isoproteic （42%） diets with varying lipid levels were formulated by adjusting the soy lecithin inclusion level. Fish with a mean initial body weight of 150 g were fed these experimental diets to apparent satiation twice daily for 8 weeks. The results showed that the growth performance and feed efficiency of Channa striata improved and plateaued as the dietary lipid level increased from 9% to 19%. In contrast, the lipid retention increased as the lipid level increased from 9% to 15%, but declined as dietary lipid further increased. Using the weight gain and protein retention as response variables, the lipid requirement of Channa striata was estimated to be 15.2% and 15.3%, respectively, by the regression analysis. In conclusion, the optimal protein and lipid requirement of Channa striata during the grow-out stage was estimated to be 41.5%-42.3% and 15.2%-15.3%, respectively.