UMAMI FUNCTIONAL PALATABILITY ENHANCER IMPROVED GROWTH, INTESTINAL MORPHOLOGY AND HEPATOPANCREAS PROTEASE ACTIVITY OF WHITE SHRIMP (PENAEUS VANNAMEI), IN PARTIAL OR TOTAL SUBSTITUTION OF SQUID PASTE

Crustaceans have highly evolved chemosensory systems which help them detect and find food items in environments with low visibility and rich in dissolved chemicals. Attractants are commonly used in shrimp farming to promote a quick identification and consumption of the feeds. These are usually fishery by-products (e.g., fish, squid or krill meal hydrolysates, squid paste) rich in amino acids and nucleotides, which are well recognized chemostimulants. However, such products often have limited or fluctuating availability and a variable composition due to seasonality and/or little control over processing conditions. The present study tested the application of a palatability enhancer containing selected sources of umami amino acids and nucleotides, none of animal origin, and with a well standardized composition to replace, partially or completely, squid paste as an attractant in white shrimp feeds. Experimental diets were formulated (43% CP, 8% CL) containing 20% fishmeal, 67% vegetable meals and 5% poultry meal (CTR) and were further supplemented with a squid paste (Ningbo Tech-Bank Aqua Feed Co., Ltd.) at either 1% (S1) or 3% (S3), a combination of 1% squid paste and a proprietary umami palatability enhancer (UPE, Lucta S.A.) at 0.1% (S1+UPE0.1) or 0.15% (S1+UPE0.15), or the UPE alone at 0.1% (UPE0.1) or 0.15% (UPE0.15). Shrimp (initial weight: 0.9±0.02g) were grown for 8 weeks in an indoor flow-through system, in 300L tanks containing 30 shrimp per tank (triplicate tanks per treatment). Shrimp fed diets S1+UPE0.1 or UPE0.15 had a significantly higher growth compared to the CTR (Fig. 1). Feeding efficiency, HSI, survival and muscle proximate composition were not significantly affected by the dietary treatments. Significantly higher protease activity was measured in the hepatopancreas of treatments S1+UPE0.15, UPE0.1 and UPE0.15 than in the CTR, and of S1+UPE0.15 versus S1 (Table 1). Additionally, significant differences were found in the micromorphology of the intestine, with treatments UPE0.15, UPE0.1 and S3 having higher intestinal fold heights than S1.