Dietary inclusion of Allium cepa and Allium sativum extract improves growth performance, haematological and immunological indices, body composition and disease resistance of prawn (Macrobrachium rosenbergii) against Vibrio parahaemolyticus infection

Abstract

This study evaluated the influence of dietary inclusion of Allium cepa (onion) and Allium sativum (garlic) extracts and their effects on growth performance, haematological and immunological responses, body composition, and disease resistance in giant freshwater prawn, Macrobrachium rosenbergii. The experimental prawns were fed with the control diet (without extracts), and the diet with 0.25% (treatment 1) and 0.5% (treatment 2) extract of both spices. After a feeding trial of 8 weeks, each group of prawn was challenged with Vibrio parahaemolyticus at a concentration of 10⁶ CFU/mL, and observed for two weeks post- challenge. The results showed that dietary extract of onion and garlic significantly enhanced (p < 0.05) the growth performance (weight gain, specific growth rate), and feed utilization efficiency (feed conversion ratio, protein efficiency ratio) compared to the control group. The treated prawn displayed improved immunological responses (p < 0.05), including high total haemocyte count, prophenoloxidase activity, superoxide dismutase activity, respiratory bursts activity compared to the control group both before and after the V. parahaemolyticus challenge. The extracts at varying concentrations have significantly influenced the enhancement of digestive enzymes and proximate composition in the muscle of prawns from the supplemented groups. After 14 days of V. parahaemolyticus challenge, the survival rate in treated prawn was significantly increased compared to control group. Among the experimental groups, prawns treated with 0.5% extract (treatment 2) exhibited superior results compared to treatment 1 and control groups in both spices. Therefore, the present research indicates that dietary onion and garlic extract may be served as an effective additive to enhance growth, non-specific immune response, and disease resistance in prawns.