Dietary protease, carbohydrase and micro-encapsulated organic acid salts individually or in combination improved growth, feed utilization and intestinal histology of Pacific white shrimp

Abstract

The present study evaluated the effects of a protease, a carbohydrase complex and a micro-encapsulated organic acid salt blend in low fish meal diet on growth, nutrient utilization, digestive enzyme activity and intestinal histology of Pacific white shrimp (Litopenaeus vannamei). A positive control diet (PC) and a negative control diet (NC) were designed to contain 20% and 10% fish meal respectively. Then a protease complex (P, 175 mg/kg), a multi-carbohydrase (C, 100 mg/kg) and a micro-encapsulated organic acid salt blend (O, 825 mg/kg) were supplemented to the NC diet individually or in combination to formulate another seven diets (P, C, O, P + C, P + O, C + O, P + C + O). The nine isonitrogenous and isoenergetic diets were fed to shrimp (2.1 g) for 49 days. The shrimp fed the PC diet had the highest weight gain (WG) (529.6%) and lowest feed conversion ratio (FCR) (1.20) while those fed the NC diet had the worst growth (382.1% and 1.55, respectively) among the treatments. The supplementation of protease, carbohydrase and micro-encapsulated organic acid salts significantly improved WG and decreased FCR (P < .05) when compared to the NC diet, but did not reach the same level as the PC treatment. The apparent digestibility coefficient (ADC) of crude protein was improved significantly in diets with the additives supplementation, individual or in combination (P < .05). However, the ADC of dry matter was improved only in protease supplemented diets (P < .05). The additives supplementation also significantly improved the hepatopancreatic protease and amylase activity (P < .05). The villus height of shrimp fed the micro-encapsulated organic acid salts supplemented diets (O, P + O, C + O, P + C + O) was significantly higher than those fed the NC diet (P < .05). However, there were no differences in whole body proximate composition, intestinal villi width and hepatopancreatic lipase activity among the treatments (P > .05). The findings showed that the individual or combined supplementation of protease, carbohydrase and micro-encapsulated organic acid salts in low fish meal diet (10% fish meal) could improve the growth performance and nutrient utilization of Pacific white shrimp.