Improving the growth performance and cholesterol metabolism of rainbow trout (Oncorhynchus mykiss) fed soyabean meal-based diets using dietary cholesterol supplementation

Abstract

A 9-week feeding trial was conducted to evaluate the effects of dietary cholesterol supplementation at different levels (0, 0·3, 0·6, 0·9, 1·2 and 1·5 %) on growth and cholesterol metabolism of rainbow trout (Oncorhynchus mykiss) fed soyabean meal (SBM)-based diets. Daily growth coefficient (DGC) steadily increased when the supplemental cholesterol was increased by up to 1·2 %, but declined upon further addition. The total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) levels in plasma generally increased when the supplemental cholesterol was increased by up to 1·2 %. Thereafter, the TC level reached a plateau, the LDL-C level showed a marked decline, whereas the HDL-C level continued to increase. Dietary cholesterol supplementation generally increased the total lipid and cholesterol levels in liver; the total lipid and TAG levels in muscle; the TC, free cholesterol, cholesteryl ester and total bile acid levels in intestinal contents; and the triiodothyronine and Ca levels in plasma. However, significant differences were mainly observed with high levels of supplemental cholesterol (0·9-1·5 %). Low levels of supplemental cholesterol (0·3-0·9 %) decreased hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase and cholesterol 7a-hydroxylase activities, but high levels of supplemental cholesterol (1·5 %) increased hepatic acyl-CoA:cholesterol acyl transferase and cholesterol 7a-hydroxylase activities. These results suggest that rainbow trout fed SBM-based diets have a certain 'cholesterol-buffering capacity', which in turn suggests the possibility of the inhibition of exogenous cholesterol absorption and/or inadequate endogenous production of cholesterol in trout fed SBM-based diets. DGC increased steadily with increasing supplemental cholesterol level up to 1·2 %, and the growth-promoting effects might be related to the alleviation of the negative effects caused by a soyabean diet and/or make up for the deficiency of endogenous cholesterol in rainbow trout.

Growth Performance, Lipid Deposition and Hepatic Lipid Metabolism Related Gene Expression in Schizothorax prenanti fed with Dietary Acidolysis-Oxidized Konjac Glucomannan Supplementation

“…HDL carries cholesterol from the peripheral tissues to the liver, whereas LDL carries cholesterol from the liver to the peripheral tissues. Thus, the LDL-C, HDL-C ratio can be used as a sign of cholesterol transport [60]. In our study, the dietary A-OKGM supplementation significantly enhanced the serum LDL-C, HDL-C ratio in fish fed with 0.4% and 1.6% A-OKGM diets.…”

Fish Oil Replacement in Current Aquaculture Feed: Is Cholesterol a Hidden Treasure for Fish Nutrition?

“…However, in the present study, juvenile rainbow trout fed for 12 weeks with either diet showed no differences in any of the measured growth and feed efficiency parameters. In a recent study on the same species [26], but using diets containing fish oil and primarily focusing on the issue of soybean inclusion in aquafeed and its hypocholesterolemic effect [40], a positive effect of dietary cholesterol supplementation on fish performances was observed. Similarly, mixed results are currently available for other teleost species.…”

“…In mammals, the availability of dietary cholesterol has been shown to affect the fatty acid metabolism [15]–[18], however, there have been only a few studies investigating dietary supplementation of cholesterol in fish feed [19]–[26]. These were all implemented using diets containing abundant levels of fish oil, and thus even the non-fortified (control) treatments were providing large amounts of dietary cholesterol.…”

Effects of dietary inclusion of soybean meal and cholesterol on the growth, cholesterol status and metabolism of the giant grouper (Epinephelus lanceolatus)

“…This phenomenon may be associated with a deficiency of cholesterol (Deng et al, ; Hossain, Focken, & Becker, ) or some anti‐nutritional factors such as saponin (Messina, ), phytosterol (Madani, Frenoux, Prost, & Belleville, ) or non‐starch polysaccharides (Deng et al, ) in SBM. In addition, studies found that cholesterol supplementation in the diet can enhance the growth performance and feed intake of channel catfish (Twibell & Wilson, ), rainbow trout (Deng, Bi, et al, ) and turbot (Yun et al, ; Yun, Mai, & Zhang, ) when the fish were fed high‐SBM diets. However, a report for Atlantic salmon found that dietary cholesterol showed no effects on growth, mortality and nutrient digestibility (Bjerkeng, Storebakken, & Wathne, ).…”