Supplemental effect of cholyltaurine and soybean lecithin to a soybean meal-based fish meal-free diet on hepatic and intestinal morphology of rainbow troutOncorhynchus mykiss

Abstract

The supplemental effects of cholyltaurine and soybean lecithin to a defatted soybean meal (SBM)-based fish meal-free diet on the hepatic and intestinal morphology of rainbow trout Oncorhynchus mykiss were investigated. A fish meal-based diet (FM), three fish meal-free diets supplemented either with soybean lecithin (SL), bovine gall powder (BG) or cholyltaurine (C-tau) and an unsupplemented fish meal-free diet (NFM), were given to fish (~11 g) for 10 weeks. The growth was the lowest in fish fed diet NFM, intermediate in fish fed diet SL and the highest in fish fed diet FM, BG and C-tau. Hepatocytes of fish fed diet NFM were atrophied, and the distal intestine of these fish showed abnormal features: disintegrated microvilli and fatty degeneration in epithelial cells and increased amount of connective tissue in the submucosa. Hepatic and intestinal histological features in fish fed diets SL, BG and C-tau were similar to those in fish fed diet FM. These results indicate that soybean lecithin, bovine bile salts and cholyltaurine have similar effects on normalizing the hepatic and intestinal morphologies of rainbow trout fed the SBM-based diet, although growth promotion effect was limited in the soybean lecithin.

Influence of soya saponin, soya lectin, and cholyltaurine supplemented to a casein-based semipurified diet on intestinal morphology and biliary bile status in fingerling rainbow trout Oncorhynchus mykiss

“…In addition, a combination of soya saponin, soya isoflavone, Ca-phytate, saccharose, and soya lectin showed morphological changes in the lamina propria of the mucosal folds and submucosa as well as in the epithelial cells [8], which were similar to those found in fish fed SBM-based diets [3,4,17]. In the present study, morphological changes of the distal intestine of fish fed a casein-based semipurified diet supplemented with soya saponin alone (diet S) occurred only in the epithelial cells, as previously reported [8].…”

“…In the hepatocytes of rainbow trout fed SBM-based diets for 10 weeks, the nuclei and cytoplasm were atrophied [2][3][4]. In the present study, the hepatocytes of fish fed diet S and diet S ?…”

“…The supplemental levels of ANFs corresponded to the inclusion of 50 g SBM/100 g diet, based on the reported ANF contents in SBM (0.6% saponin [10] and 0.015% lectin [11]) and the purity of the substances used in this study. The supplemental level of C-tau was the same as in previous study [4]. In diet SBM, essential amino acids (EAAs) were supplemented to simulate the digestible EAAs composition of a fish-meal-based diet [2].…”

“…Feeding defatted and heat-treated soybean meal (SBM)-based diets causes morphological changes in the distal intestine and liver of rainbow trout Oncorhynchus mykiss [1][2][3][4][5][6]. Several soybean antinutritional factors (ANFs), e.g., saponin, phytate, isoflavone, lectin, and oligosaccharides are suggested to affect nutrient uptake and metabolism in fish [7].…”

“…On the other hand, the decrease of total biliary bile acid content, changes in biliary conjugated bile salt composition, and morphological changes in the distal intestine of rainbow trout fed SBM-based diets were prevented by supplementation of phospholipids (soya lecithin) [1,4], bovine gall powder [2][3][4], and cholyltaurine (C-tau) [4]. These results suggest that bile salt status affects the morphological conditions of the distal intestine in rainbow trout fed SBM diets.…”