Palma Mariana, Trenkner Lauren H, Rito João, Tavares Ludgero C, Silva Emanuel, Glencross Brett D, Jones John G, Wade Nicholas M, Viegas Ivan
Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
CSIRO Agriculture and Food, Queensland Biosciences Precinct, Brisbane, QLD, Australia.
Front Physiol. 2020 Mar 20;11:205. doi: 10.3389/fphys.2020.00205. eCollection 2020.
Practical diets for commercial barramundi production rarely contain greater than 10% starch, used mainly as a binding agent during extrusion. Alternative ingredients such as digestible starch have shown some capacity to spare dietary protein catabolism to generate glucose. In the present study, a carnivorous fish species, the Asian seabass () was subjected to two diets with the same digestible energy: Protein (P) - with high protein content (no digestible starch); and Starch (S) - with high digestible (pregelatinized) starch content. The effects of a high starch content diet on hepatic glycogen synthesis as well as the muscle and liver metabolome were studied using a complementary approach of H and H NMR. The hepatosomatic index was lower for fish fed high starch content diet while the concentration of hepatic glycogen was similar between groups. However, increased glycogen synthesis via the direct pathway was observed in the fish fed high starch content diet which is indicative of increased carbohydrate utilization. Multivariate analysis also showed differences between groups in the metabolome of both tissues. Univariate analysis revealed more variations in liver than in muscle of fish fed high starch content diet. Variations in metabolome were generally in agreement with the increase in the glycogen synthesis through direct pathway, however, this metabolic shift seemed to be insufficient to keep the growth rate as ensured by the diet with high protein content. Although liver glycogen does not make up a substantial quantity of total stored dietary energy in carnivorous fish, it is a key regulatory intermediate in dietary energy utilization.
用于商业尖吻鲈养殖的实用饲料中淀粉含量很少超过10%，淀粉主要在挤压过程中用作粘合剂。诸如可消化淀粉等替代成分已显示出一定能力，可减少膳食蛋白质分解代谢以生成葡萄糖。在本研究中，一种肉食性鱼类——亚洲海鲈（）被投喂两种具有相同可消化能量的饲料：蛋白质（P）饲料——蛋白质含量高（不含可消化淀粉）；以及淀粉（S）饲料——可消化（预糊化）淀粉含量高。使用氢核磁共振（H NMR）和碳核磁共振（C NMR）的互补方法研究了高淀粉含量饲料对肝糖原合成以及肌肉和肝脏代谢组的影响。投喂高淀粉含量饲料的鱼的肝体指数较低，而两组之间肝糖原浓度相似。然而，在投喂高淀粉含量饲料的鱼中观察到通过直接途径的糖原合成增加，这表明碳水化合物利用率提高。多变量分析还显示两组在两种组织的代谢组方面存在差异。单变量分析显示，投喂高淀粉含量饲料的鱼的肝脏代谢变化比肌肉更多。代谢组的变化总体上与通过直接途径的糖原合成增加一致，然而，这种代谢转变似乎不足以维持高蛋白含量饲料所确保的生长速度。尽管肝糖原在肉食性鱼类储存的膳食总能量中所占比例不大，但它是膳食能量利用中的关键调节中间体。
