In this study, we conducted a 56-d feeding trial to investigate the effects of replacing the fish oil (FO) with palm oil (PO) on the performance, tissue fatty acid (FA) composition, and mRNA levels of genes related to hepatic lipid metabolism in grouper ( Epinephelus coioides ). Five isolipidic (13% crude lipid) and isonitrogenous (48% CP) diets were formulated by incrementally adding PO to the control diet (25% fish meal and 9% added FO) to replace FO in the control diets. Triplicate groups of 30 groupers (initial weight: 12.6 ± 0.1 g) were fed one of the diets twice daily, to apparent satiety. The replacement of FO with 50% PO revealed maximum growth without affecting the performance and whole-body proximate compositions, and replacing FO with 100% PO revealed a comparable ( P > 0.05) growth with that of the control diet, suggesting PO as a suitable alternative to FO. The analysis of FA profiles in the dorsal muscle and liver though reflected the FA profile of the diet, PO substitutions above 50% could compromise ( P < 0.05) the FA profile in the liver and flesh of the fish species in comparison with the control diet. Furthermore, the mRNA levels of FAS , G6PD , LPL , PPARΑ , and Δ6FAD genes in the liver had positive linear and/or quadratic responses, but the SCD , HSL , ATGL , FABP , SREBP-1C and ELOVL5 had the opposite trend, with increasing dietary PO inclusion levels, whereas the mRNA level of ACC was not affected by dietary treatments. The optimal level of PO substitution for FO was estimated to be 47.1% of the feed, based on the regression analysis of percent weight gains against dietary PO inclusion levels; however, it might affect the FA profile in the liver and flesh of the fish species, and further study is required to investigate whether the changes in tissue FA composition will affect the welfare and market value over a production cycle of grouper.

A 56-day feeding trial was conducted to investigate the effects of dietary lactoferrin (LF) supplementation on the growth performance and intestinal health of juvenile orange-spotted groupers fed high-soybean-meal (SBM) diets. The control diet (FM) and high-soybean-meal diet (SBM60) were prepared to contain 480 g/kg protein and 110 g/kg fat. Three inclusion levels of 2, 6, and 10 g/kg LF were added into the SBM60 to prepare three diets (recorded as LF2, LF6, and LF10, respectively). The results showed that the supplementation of LF in SBM60 increased the growth rate in a dose-dependent manner. However, the feed utilization, hepatosomatic index, whole-body proximate composition, and the abundance and diversity of intestinal microbiota did not vary across the dietary treatments (p > 0.05). After the dietary intervention with LF, the contents of the intestinal malondialdehyde, endotoxin, and d-lactic acid, as well as the plasma low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and total cholesterol were lower, and the intestinal activities of the glutathione peroxidase, lipase, trypsin, and protease were higher in the LF2-LF10 groups than that in the SBM60 group (p < 0.05). The supplementation of LF in SBM60 increased the muscle layer thickness of the middle and distal intestine and the mucosal fold length of the middle intestine vs. the SBM60 diet (p < 0.05). Furthermore, the supplementation of LF in SBM60 resulted in an up-regulation of the mRNA levels for the IL-10 and TGF-β1 genes and a down-regulation of the mRNA levels of the IL-1β, IL-12, IL-8, and TNF-α genes vs. the SBM60 diet (p < 0.05). The above results showed that a dietary LF intervention improves the growth and alleviates soybean meal-induced enteritis in juvenile orange-spotted groupers. The dietary appropriate level of LF was at 5.8 g/kg, through the regression analysis of the percent weight gain against the dietary LF inclusion levels.

The aim of this study was to investigate the effects of substituting soybean oil (SO) for fish oil (FO) on the performance, tissue fatty acid (FA) composition, plasma components, liver metabolic enzyme activity and mRNA levels of genes related to lipid metabolism in the liver of groupers (Epinephelus coioides). We formulated five isolipidic and isoproteic diets with increasing SO levels (0, 250, 500, 750 and 1000 g/kg, respectively). Triplicate groups of 30 groupers (initial mean body weight of 12.6 g/ fish) were fed one of the diets twice daily, to apparent satiety across a feeding period of 56 days. The growth performance, whole-body composition, and protein and lipid muscle contents did not differ across the dietary treatments. In contrast, the liver lipid content had positive linear and quadratic responses to the increasing dietary SO levels, but the liver protein content had the opposite trend, and the highest lipid value and lowest protein value occurred in the 250 and 1000 g/kg SO diets, respectively. There were no significant effects of increasing dietary SO inclusion levels on any of the plasma components and parameters of liver metabolic enzyme activity, except for acetyl coenzyme A carboxylase and hepatic lipase, which showed linear and quadratic responses to increasing dietary SO inclusion levels and peaked at 1000 and 250 g/ kg SO inclusion level, respectively. However, the FA profiles of the dorsal muscle and liver generally reflected the FA profile of the diet. Furthermore, the mRNA levels of fas, acc, g6pd, lpl, pparα, cpt-1, srebp-1c, δ6fad and elovl5 in the liver exhibited positive linear and/or quadratic responses to dietary SO inclusion levels. However, negative linear and/or quadratic responses were observed for the mRNA levels of hsl and atgl in the liver, with increasing dietary SO inclusion levels. The mRNA levels of scd and fabp in the liver were not affected by the dietary SO inclusion level. These results indicate that FO could be replaced completely by SO without affecting growth. However, the inclusion of SO at levels higher than 500 g/kg could compromise the FA profile in the liver and flesh of the fish species. These results provide a novel insight into the potential utilization of SO in grouper feeds. | 1495 HE Et al.

An 8-week feeding trial was conducted to investigate whether dietary sodium butyrate (SB) administration alleviates growth reduction and enteritis of orange-spotted grouper (Epinephelus coioides) caused by high soybean meal (SBM) feeding. The control diet (FM diet) was formulated to contain 48% protein and 11% fat. Soybean meal was used to replace 60% FM protein in FM diet to prepare a high SBM diet (HSBM diet). Sodium butyrate (SB) at 0.1%, 0.2%, and 0.3% were added to HSBM diets to prepare three diets. Triplicate groups of 30 groupers (initial weight: 33.0 ± 0.3 g) were fed one of the diets twice daily, to apparent satiety. HSBM diets had lowered growth rate and feed efficiency vs FM diets (P &lt;0.05). Growth rate and feed efficiency were improved by dietary SB administration and were in a dose-dependent manner (P &lt;0.05). A similar pattern to the growth rate was observed for plasma LDL-C and gut digestive activity of lipase, trypsin, and protease, but the opposite trend was observed for intestinal contents of D-lactic acid and endotoxin, in response to dietary SB inclusion levels (P &gt;0.05). The muscular thickness in the middle and distal intestines in SB-treated diets were higher than that in HSBM diets (P &lt;0.05). The mRNA levels of intestinal pro-inflammatory cytokines IL-8, IL-1β, IL-12 and TNF-α had a decreasing trend, and the mRNA level of intestinal anti-inflammatory cytokine TGF-β1 had the opposite trend, with increasing SB inclusion levels (P &lt; 0.05). The above results indicate that dietary SB intervention could enhance growth and feed utilization of groupers with SBM-induced enteritis by promoting intestinal digestive enzyme activities, reducing mucosa permeability, maintaining the integrity of intestinal morphology and attenuating the intestinal inflammatory response.

A 56-day feeding trial was conducted to investigate the effects of dietary lactoferrin (LF) supplementation on growth performance and intestinal health of juvenile orange-spotted groupers (Epinephelus coioides) fed high soybean meal (SBM) diets. The control diet (FM) and high soybean meal diet (SBM60) were prepared to contain 48% protein and 11% fat. Three inclusion levels of 2, 6, and 10 g/kg LF were added into the SBM diets to prepare three experimental diets (recorded as LF2, LF6, and LF10, respectively). The results showed that supplementation of LF in SBM diets increased growth rate in a dose dependent manner. However, feed utilization, hepatosomatic index, whole-body proximate composition and the abundance and diversity of intestinal microbiota did not vary across dietary treatments (P > 0.05). After dietary intervention with LF, the contents of intestinal malondialdehyde, endotoxin, and D-lactic acid, as well as plasma low density lipoprotein cholesterol, high density lipoprotein cholesterol and total cholesterol were lower, and the intestinal activities of glutathione peroxidase, lipase, trypsin, and protease were higher in LF2-LF10 groups than that in SBM60 group (P < 0.05). Supplementation of LF in SBM diets increased the muscle layer thickness of middle and distal intestine and the mucosal fold length of middle intestine vs SBM60 diet. Furthermore, supplementation of LF in SBM diets resulted in an up-regulation of the mRNA levels for IL-10 and TGF-β1 genes and a down-regulation of the mRNA levels of IL-1β, IL-12, IL-8, and TNF-α genes vs SBM60 diet (P < 0.05). The above results showed that dietary LF intervention could improve the growth and alleviate soybean meal induced enteritis in juvenile orange-spotted groupers. The dietary appropriate level of LF was at 5.8 g/kg, through the regression analysis of percent weight gain against dietary LF inclusion levels.