Dietary lipid concentrations influence growth, body composition, morphology of the liver and mid-intestine, and antioxid
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Dietary lipid concentrations influence growth, body composition, morphology of the liver and mid-intestine, and antioxidant status of marbled eel (Anguilla marmorata) Shi-Jun Chen 1,2 & Peng Liu 1,2 & You-Ming Jia 1,2 & Hong-Ping Liao 1,2 & Shao-Xuan Zhu 1,2 & Li-Liu Zhou 1,2 & Xue-Ming Dan 1,2 & Li Liu 1,2 & Jia-Hao Li 3 & Su-Bi Zheng 3 & Jun-Jiang Yang 3 & Lian Gan 1,2 Received: 26 February 2020 / Accepted: 4 August 2020/ # Springer Nature Switzerland AG 2020
Abstract
An 8-week feeding trial was conducted to explore the effect of dietary lipid concentrations on growth, body composition, morphology of liver, and mid-intestine and antioxidant status in marbled eel (Anguilla marmorata). Fish (initial average weight 6.86 ± 0.11 g) were held in 18 tanks (inside diameter 80 cm, height 60 cm, volume 300 L, 25 fish/tank), with triplicate treatment groups being fed to apparent satiation twice each day on isonitrogenous (421 g/kg crude protein) diets containing different concentrations of lipid (41.2, 73.9, 113.9, 146.2, 178.1, and 216.7 g/kg). The sampling procedure was implemented after 24 h of fasting. Fish fed the diets with 178.1 and 216.7 g lipid/kg grew better than fish fed the other diets. The lowest feed intake and the highest feed conversion rate were found in 41.2 g/kg group. Muscle lipid concentrations and heights of intestinal folds, enterocytes, and microvilli in mid-intestine increased as dietary lipid concentrations increased from 41.2 to 178.1 g/kg. Hepatocyte hypertrophy and lipid vacuolization were seen in liver of the fish fed 216.7 g/kg diet. Based on broken-line analysis of serum total antioxidant capacity and quadratic regression analysis of serum glutathione peroxidase and catalase, it was concluded that dietary lipid concentrations of 125.5–159.2 g/kg promoted antioxidant status. A broken-line analysis of data for specific growth rate and weight gain gave an estimated optimal dietary lipid concentration of 195.3– 198.7 g/kg. Marbled eel had quite a high demand for dietary lipid to support good growth, but excessive lipid level (216.7 g/kg) may have an adverse impact on liver structure. Moreover, marbled eel may not tolerate high concentration of dietary carbohydrate. Keywords Anguilla marmorata . Lipid . Feed formulation . Growth metrics . Serum enzymes
Shi-Jun Chen and Peng Liu contributed equally to this work.
* Lian Gan [email protected] Extended author information available on the last page of the article
Aquaculture International
Introduction Marbled eel (Anguilla marmorata), a carnivorous fish with meat of high nutritional value, is found in parts of Asia (Liang et al. 2016). Its aquaculture production is lower than that of two other commercially important eel species, the European eel (A. anguilla) (global aquaculture production, 6994 t in 2016) and the Japanese eel (A. japonica) (278,177 t in 2016) (Food and Agriculture Organization of the United Nations (FAO) 2016). In recent years, the catches of glass eels of European eel and Japanese eel have fallen sharply, but wild glass eels
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