Effects of different carbohydrates on growth, hepatic glucose metabolism, and gut microbiome of Florida pompano (Trachinotus carolinus)

A 10-week feeding trial was conducted to determine an appropriate carbohydrate source by evaluating growth performance, feed utilization, hepatic enzymes activity, whole-body fatty/amino acids composition, liver transcriptomics and gut microbiome of Florida pompano (Trachinotus carolinus). Five isonitrogenous (46.7 % crude protein), isolipidic (15.2 % crude lipid) and isocaloric (385Kcal/100 g digestible energy) diets were formulated containing 14 % of different sources of carbohydrates: whole wheat grain flour (WG), wheat starch (WS), whole corn grain flour (CG), corn starch (CS) and dextrinized corn starch (DCS). The results indicated that Florida pompano survival remained high (91-100) % with no significant difference among treatments; and significantly higher percentage weight gain (PWG), specific growth rate (SGR), and feed efficiency (FE) were observed in fish fed WG diet compared to those fed CS and DCS diets. Protein efficiency ratio (PER) was significantly higher in fish fed WS diet in contrast to those fed CS and DCS diets. Fish fed WG, CG and CS diets presented significantly lower crude fat content, while higher ash content only appeared in fish fed WG diet compared to those fed DCS diet. The lowest taurine content was found in fish fed DCS diet. The lowest blood glucose, plasma cholesterol, and hepatic glucose 6-phosphate were measured in fish fed WG diet, while its hepatic glycogen content was higher than those fed WS diet. Liver transcriptomic analysis revealed differentially expressed genes related to glycolysis, gluconeogenesis, and lipogenesis. The microbial community presented high diversity and richness among treatments. Overall, results indicated that WG is the more appropriate dietary carbohydrate source based on growth performance, physio-biochemical, and molecular approaches. These data are critical when formulating a complete commercial feed for sustainable and profitable culturing of Florida pompano.