Total replacement of soybean meal by rice distilled dried grain soluble (DDGS) with lysine supplementation: effect on growth, nucleic acid content, digestive enzyme activity, and health status in Carp (

Objective: Present study was conducted to evaluate the suitability of Rice DDGS as a protein source and its influence, with or without lysine supplementation, on nutrient utilization, growth and health status of Cirrhinus mrigala juveniles. Methods: Juvenile of Cirrhinus mrigala (14.00 ± 0.10 g) were fed ad-libitum for 45 days with twelve iso-proteinous and iso-lipidic practical diets containing 0, 6, 12, 18, 24, 30% of rice DDGS replacing up to total dietary soybean meal (SBM) with and without lysine supplementation (0.1%). Result: At the end of the feeding trial, treatment fed with a diet having 18% or more rice DDGS recorded a significant decrease in growth performance in juveniles. However, lysine (0.1%) supplementation in the diet showed an improved growth performance of juveniles as compared to the non-supplemented counterpart diet containing at least 30% rice DDGS. Fish fed diet D30 had the lowest RNA/muscle mass and RNA/DNA ratio. The digestive enzyme activities were significantly higher in the lysine-supplemented group compared to the non-supplemented group. The haemato-immunological parameters tended to increase with an increasing level of rice DDGS up to 12% but the differences beyond this were not significant with the control. Conclusion: Considering all the factors, a negative trend was observed and signalled that more than 12% inclusion of DDGS in practical diets without supplementation of lysine recorded negative physiological effects, however, supplementation of lysine nullifies the negative consequence of total substitution of SBM by rice DDGS. Overall, the present study gave a demonstration of the high potential of rice DDGS as a substitute for the soybean meal forages for C. mrigala, and the incorporation of rice DDGS can be augmented to at least 30% (highest level assessed) if lysine is added.