EVALUATION OF BILE SALT AS CHOLESTEROL REPLACER IN DIET FOR WHITE SHRIMP

Yu-Hung Lin1
 
Department of Aquaculture, National Pingtung University of Science and Technology, Taiwan,
yuhunglin@mail.npust.edu.tw

For shrimp, fish meal is the most ideal protein source. It is important to find adequate alternative ingredients for fish meal due to the limited global supply and increasing price of fish meal. Soybean meal is the most widely used plant ingredient for shrimp aquaculture. Cholesterol functions in cell membrane and molting function in shrimp. However, due to absence of cholesterol in soybean meal and lack of de novo cholesterol-synthesis ability for shrimp, it is necessary to supplement cholesterol in diet for shrimp when the feed containing high levels of soybean meal. Our previous study found that dietary fish meal protein replaced by soybean meal caused poor growth, low tissue cholesterol concentration and depressed molting relative gene expression, including ecdysteroid receptor b, retinoic acid X receptor, hemocyanin, chitin synthase, chitinase isoenzyme and beta-actin gene. While cholesterol was supplemented in soybean meal-based diet, tissue cholesterol concentration and molting relative gene expression were improved for the shrimp. Because cholesterol is the most expensive ingredient in shrimp diet, it is worthy to find an alternate to cholesterol. In our recent work, a growth trial was to evaluate the potentiality of dietary bile salt as cholesterol replacer on cholesterol status and molting relative gene expression of white shrimp. A basal diet (soybean replaced 70% fish meal protein) was supplemented with 0.1 (SBMCA0.1) and 0.2% (SBMCA0.2) bile salt. The diet with all fish meal (FM) was also included for comparison. Hepatopancreas and hemolymph cholesterol concentration were higher in FM group than those in other dietary treatments. ECRb gene expression was the highest in FM and SBMCA0.2 groups, followed by the SBMCA0.1 group, and the lowest in SBM group. HCyn gene expression was higher in FM group than that in the SBM group. The results indicated that bile salt could partially replace cholesterol in diet for shrimp and maintain the normal cholesterol status and molting relative gene expression.