Khejri seed extract (KSE) enhances the growth, digestive, metabolic, and immunological responses of Labeo rohita fingerlings

ROHITASH YADAV^1*Manish Jayant^1*Narinder Kumar Chadha^1*Ved Prakash Saini²Paramita Banerjee Sawant¹Manohar Lal Ojha³Bhanu Kumar Sharma³Dharmendra Kumar Meena⁴

• ¹Central Institute of Fisheries Education (ICAR), Mumbai, Maharashtra, India
• ²Bihar Animal Sciences University, Patna, Bihar, India
• ³Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan, India
• ⁴Central Inland Fisheries Research Institute (ICAR), Kolkata, West Bengal, India

A sixty-day feeding trial was conducted to evaluate the dietary effect of khejri seed extract (KSE) on the growth performance and immunological responses of rohu (Labeo rohita) fingerlings. Following this trial, a fifteen-day challenge study assessed the rohu fingerlings' resistance against Aeromonas hydrophilia. Four experimental diets were supplemented with different levels of khejri seed extract (KSE) viz. 0.0, 2.5, 5.0, and 7.5 g KSE kg -1 of diet and designated as C, KSE0.25, KSE0.50, and KSE0.75, respectively. The supplementation of dietary KSE led to significant improvements in growth performance and protein utilization in rohu fingerlings (P< 0.05). The activity of digestive (except amylase) and metabolic enzymes (except lactate dehydrogenase in muscle) activities varied significantly (P<0.05). For the enzymes superoxide dismutase (SOD) and catalase (CAT), the observed trend was control > KSE0.25 > KSE0.50 > KSE0.75 in both pre-and post-challenge studies. Total serum protein showed significant variations (P < 0.05) in both pre-and post-challenge studies, with albumin and globulin concentrations being significantly higher in the KSE0.50 group compared to control during the post-challenge phase. Moreover, KSE supplementation significantly enhanced the respiratory burst activity and haematological parameters (except total leukocyte count in the pre-challenge and serum glucose levels in pre-and post-challenge study) of rohu fingerlings (P<0.05). Following A. hydrophilia challenge, fish mortality significantly decreased with higher dietary KSE levels (P<0.05), reaching the lowest mortality in the KSE0.50 group. These results suggest that supplementing the diet with 5.0 g kg -1 khejri seed extract can effectively enhance growth, improve feed conversion, boost immunity, and increase survival against A. hydrophila infection in rohu fingerlings.