Effects of dietary carbohydrate source on Florida pompano growth and nutritional physiology (Trachinotus carolinus)
A 10-week feeding trial was conducted to determine an appropriate carbohydrate source evaluating growth performance, feed utilization, hepatic activity, whole-body fatty/amino acid composition, liver transcriptomics and gut microbiome for Florida pompano (Trachinotus carolinus). Five isonitrogenous (46.67% crude protein), iso-lipidic (15.15% crude lipid) and isocaloric (385Kcal/100g digestible energy) diets were formulated containing 14% of different source 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: highest percentage weight gain (PWG) and specific growth rate (SGR) were found in fish fed with whole wheat grain flour (WG) diet, the highest feed efficiency (FE) was shown in WG and WS diets, lowest conversion index (CI) was observed in fish fed with WG diet and the highest protein efficiency ratio (PER) was shown in in WS diet. The poorest values were observed in fish fed with CS and DCS diets. The whole-body crude protein and total amino acid and fatty acids composition was not significantly affected by different sources of carbohydrates in the diets. In fish fed with the WG diet, glucose levels in plasma and liver were significantly low while liver glycogen content was statistically high compared to the other diets. Liver transcriptomics analysis revealed differentially expressed genes (DEGs) and gene ontology (GO) enrichment analysis highlighting up/down regulated biological functions depending on the carbohydrate source. The microbial community presented high diversity and richness among treatments. Overall, results indicated that whole wheat grain flour is the more adequate dietary carbohydrate source based on production performance, physio-biochemical and molecular approaches. These data are critical when formulating a complete commercial feed for sustainable and profitable culturing of Florida pompano.