Effect of Mucuna bracteata leaf meal diet on growth, digestion and metabolism in Cyprinus carpio (Linnaeus 1758)

The current study evaluated mucuna leaf meal (MLM) as an alternative for de-oiled rice bran (DORB) in the Cyprinus carpio fingerling diet. Following a complete randomised design, a 60-day feeding experiment was carried out, where four isonitrogenous (32% crude protein) and iso-caloric (356 kcal DE 100 g-1) diets were prepared to constitute the following treatments; C (30% DORB, 0% MLM), T1 (20% DORB, 10% MLM), T2 (10% DORB, 20% MLM) and T3 (0% DORB, 30% MLM). Significant differences (p<0.05) were observed among treatments in terms of weight gain percentage (WG), protein efficiency ratio (PER) and specific growth rate (SGR). The growth performance of C. carpio fingerlings in the 30% MLM group (T3) was comparable to that of the control group (C, 30% DORB). Notably, fish fed with T2 diets exhibited better growth compared to those in other treatments. Digestive enzyme activities remained largely unchanged, except for amylase activity, which showed a significant increase in the T2 group. Additionally, alanine aminotransferase (ALT) activity in both muscle and liver was significantly elevated (p<0.05) in this group. These findings indicate that MLM can serve as an effective alternative to DORB in the diet without causing adverse effects, with the 20% MLM diet providing optimal growth and physiological benefits. However, malate dehydrogenase (MDH) and lactate dehydrogenase (LDH) activities on hepatic and muscular tissues were significantly higher (p<0.05) in 30% MLM groups. Based on this, it can be concluded that the MLM can fully replace DORB (30%) without generating any detrimental consequences in the diet of C. carpio. Keywords: Common carp, De-oiled rice bran, Digestibility coefficient, Lactate dehydrogenase, Malate dehydrogenase, Protein efficiency ratio, Specific growth rate