Dietary starch promotes hepatic lipogenesis in barramundi (Lates calcarifer)



Wade NM, Trenkner LH, Viegas I, Tavares LC, Palma M, Skiba-Cassy S, Dias K, Vachot C, Araujo BC, Bourne N, Blyth D, Irvin S & Glencross BD (2020) Dietary starch promotes hepatic lipogenesis in barramundi (Lates calcarifer). British Journal of Nutrition, 124 (4), pp. 363-373.

Barramundi (Lates calcarifer) are a highly valued aquaculture species, and, as obligate carnivores, they have a demonstrated preference for dietary protein over lipid or starch to fuel energetic growth demands. In order to investigate how carnivorous fish regulate nutritional cues, we examined the metabolic effects of feeding two isoenergetic diets that contained different proportions of digestible protein or starch energy. Fish fed a high proportion of dietary starch energy had a higher proportion of liver SFA, but showed no change in plasma glucose levels, and few changes in the expression of genes regulating key hepatic metabolic pathways. Decreased activation of the mammalian target of rapamycin growth signalling cascade was consistent with decreased growth performance values. The fractional synthetic rate (lipogenesis), measured by TAG 2H-enrichment using 2H NMR, was significantly higher in barramundi fed with the starch diet compared with the protein diet (0·6 (se 0·1) v. 0·4 (se 0·1) % per d, respectively). Hepatic TAG-bound glycerol synthetic rates were much higher than other closely related fish such as sea bass, but were not significantly different (starch, 2·8 (se 0·3) v. protein, 3·4 (se 0·3) % per d), highlighting the role of glycerol as a metabolic intermediary and high TAG-FA cycling in barramundi. Overall, dietary starch significantly increased hepatic TAG through increased lipogenesis. Compared with other fish, barramundi possess a unique mechanism to metabolise dietary carbohydrates and this knowledge may define ways to improve performance of advanced formulated feeds.

Liver; Fish; Nutrigenomics; 2H; Lipogenic flux; NMR

British Journal of Nutrition: Volume 124, Issue 4

FundersCommonwealth Scientific Industrial Research Organisation
Publication date28/08/2020
Publication date online19/03/2020
Date accepted by journal10/03/2020

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Professor Brett Glencross
Professor Brett Glencross

Honorary Professor, Institute of Aquaculture