Effects of Dietary Carbohydrate‐to‐Lipid Ratios on Growth and Body Composition of Orange‐spotted Grouper Epinephelus coioides

Abstract

Growth performance of juvenile Orange-spotted Grouper Epinephelus coioides fed isonitrogenous (45% crude protein) and isoenergetic diets with varying carbohydrate-to-lipid ratios (0 to 10.9) were evaluated. Triplicate groups of 18 fish (initial mean individual body weight, 16.4 g/) were fed to satiety for 8 weeks. At the termination of this trial, significant differences (P < 0.05) were found on the growth performance. Weight gain and specific growth rate values increased with decreasing dietary carbohydrate-to-lipid ratios. The highest feed conversion ratio value and the lowest protein efficiency ratio value were observed in fish fed the 10.9 carbohydrate-to-lipid ratio diet. Besides, fish fed the 10.9 carbohydrate-to-lipid ratio exhibited the lowest nitrogen retention and energy retention values. With the diet carbohydrate-to-lipid ratios decreasing, hepatosomatic index values were reduced significantly (P < 0.001), while the intraperitoneal fat index values showed an inverse trend. Whole-body protein content was reduced with the decrease in dietary carbohydrate-to-lipid ratios, whereas whole-body lipid content increased significantly with decreasing dietary carbohydrate-to-lipid ratios (P < 0.001) while the whole-body moisture content showed a reverse trend. Additionally, liver lipid content increased with the decrease in dietary carbohydrate-tolipid ratios, while contrasting results were found in liver glycogen content. The results of this study suggest that the suitable dietary carbohydrate-to-lipid ratio for Orange-spotted Grouper is 0.5 in the isonitrogenous (45% crude protein) and isoenergetic diets, and this species is better adapted to utilizing lipids rather than carbohydrates.

Effects of Dietary Carbohydrate/Lipid Ratios on Growth, Feed Utilization, Hematology Parameters, and Intestinal Digestive Enzyme Activities of Juvenile Hybrid Grouper (Brown‐Marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♂)

“…Thus, it seems that grouper could efficiently utilize CHO, and the poor growth recorded in fish that were fed diets with a CHO/L ratio of 6.88 (27.5% CHO/4% L) or 3.83 (23% CHO/6% L) probably resulted from insufficient lipid content in those diets. Similar results were also reported for Orange-Spotted Grouper E. coioides (Wang et al 2017) and other fish species, such as Redbelly (Gao et al 2010), and Korean Rockfish Sebastes schlegelii (Lee and Kim 2009). Insufficient lipid and essential fatty acid content in the diet could also have led to the higher DFI in fish that were given diets with CHO/L ratios of 3.83 and 6.88 in comparison with the other dietary treatments, which was in agreement with studies of Walking Catfish Clarias batrachus (Jafri 1998) and Wuchang Bream Megalobrama amblycephala (Li et al 2013).…”

“…Similar results were also reported for Orange‐Spotted Grouper E. coioides (Wang et al. ) and other fish species, such as Redbelly Tilapia Tilapia zillii (El‐Sayed and Garling ), Grass Carp Ctenopharyngodon idella (Gao et al. ), and Korean Rockfish Sebastes schlegelii (Lee and Kim ).…”

“…), and Hong Kong Grouper Epinephelus akaara (Wang et al. ). However, high levels of dietary CHO could cause intracellular damage due to excess deposition of glycogen particles and impaired liver detoxification capacity by influencing the metabolism and toxicity of several minerals (Hilton and Hodson ; Kumar et al.…”

“…Although in general, fish (particularly carnivorous species) exhibit limited digestible and metabolic capacity to efficiently utilize CHO (Polakof et al 2012), inclusion of CHO in the diet could increase protein retention by preventing catabolism of this expensive nutrient for energy needs (Hemre et al 2002). Furthermore, it has been observed that a suitable supplement of CHO in the diet improved feed utilization and growth in several carnivorous species, including the Rainbow Trout Oncorhynchus mykiss (Bergot 1979), Atlantic Salmon Salmo salar (Hemre et al 1995), Cobia Rachycentron canadum (Ren et al 2011), and Hong Kong Grouper Epinephelus akaara (Wang et al 2017). However, high levels of dietary CHO could cause intracellular damage due to excess deposition of glycogen particles and impaired liver detoxification capacity by influencing the metabolism and toxicity of several minerals (Hilton and Hodson 1983;Kumar et al 2005).…”

Effect of Dietary Energy to Protein Ratio on Growth, Biological Indices, Proximate Composition, and Amino Acid Profiles in the Muscle of Varicorhinus macrolepis

“…Peres and Oliva‐Teles () and Wang et al. () also observed the decreased hepatosomatic index when dietary lipid level increased and believed that the decreased hepatosomatic index seemed to correlate to the decreased carbohydrate level in diets. Lee et al.…”