European Journal of Nutrition & Food Safety

This study evaluated Delonix regia leaf meal as a replacer of deoiled rice bran in diets for Labeo rohita fingerlings, focusing on growth performance, feed utilization and protein digestibility. Four isocaloric and isonitrogenous diets were formulated with 0% (control), 30% (T1), 60% (T2) and 100% (T3) replacement of deoiled rice bran by D. regia leaf meal. Total weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and apparent protein digestibility were recorded after the feeding trial. Dietary treatments significantly affected weight gain, with fish fed the 60% replacement diet (T2) showing the highest gain (34.26 ± 1.14 g), followed by T3 (32.74 ± 1.14 g), while the control and T1 groups exhibited lower gains (26.13 ± 1.14 g and 27.44 ± 1.14 g; p < 0.05). FCR and PER did not differ significantly among diets; however, numerically lower FCR values were observed in T1 and T2 (1.47 ± 0.10 and 1.49 ± 0.17) compared with the control and T3 (1.73 ± 0.16 and 1.81 ± 0.03), and higher PER values were recorded in T1 and T2 (0.68 ± 0.04–0.07) than in the control and T3 (0.59 ± 0.06 and 0.55 ± 0.01). Apparent protein digestibility increased with D. regia inclusion, ranging from 72.00 ± 0.90% in the control to 77.97 ± 0.39% in T3, with T1 and T2 showing intermediate but statistically comparable values. Overall, the results indicate that D. regia leaf meal can effectively replace deoiled rice bran up to 60% in L. rohita diets without impairing growth, feed efficiency or protein utilization, and may improve protein digestibility at higher inclusion levels.