Utilisation of mealworm (Tenebrio molitor) oil in Pacific white shrimp (Litopenaeus vannamei) diet

Abstract

Mealworm (Tenebrio molitor) and their derivatives are sustainable ingredients in aquaculture feeds. This study evaluated the effect of fish oil (FO) replacement with mealworm oil (MO) on growth performance, non-specific immune responses and disease resistance against Vibrio parahaemolyticus for Pacific white shrimp (Litopenaeus vannamei). FO in a control diet (Con) was replaced with MO at levels of 25%, 50%, 75% and 100% (designated as MO25, MO50, MO75 and MO100, respectively). A total of 480 shrimp (initial mean body weight, 0.884 ± 0.004 g) were randomly distributed into 20 acrylic tanks (240 L) in quadruplicates groups and fed the experimental diets for 58 days. Growth performance was significantly higher in all MO groups than in Con group. Shrimp fed MO50 and MO75 diets showed significantly improved feed utilisation efficiency than shrimp fed Con diet. Lipid metabolism related-gene expressions of fatty acid binding protein and triacylglycerol lipase in hepatopancreas were significantly downregulated by increment of MO in the diets. Digestibility of protein, lipid, energy and dry matter were not significantly affected by the dietary treatments, while digestibility of poly-unsaturated fatty acids (PUFAs) were significantly decreased by dietary MO supplementation. The levels of n-3 PUFA in muscle and hepatopancreas were significantly decreased with increasing MO levels in the diets. Cumulative survival of shrimp in a challenge test against V. parahaemolyticus was higher in all MO groups and significantly higher in MO25 group than in Con group. Non-specific immune responses were significantly enhanced in all MO groups than in Con group. Replacement of FO with MO in the diets significantly increased haemolymph cholesterol and triglyceride levels. Our findings suggest that MO could be utilised as a promising substitute for FO in the diets of L. vannamei and optimal FO replacement level would be 50% for growth and 25% for disease resistance against V. parahaemolyticus.