高植物性蛋白飼料添加肉鹼對龍膽石斑成長、體組成、肝臟氧化狀態、血液生化指標及脂質代謝之影響

本實驗目的為探討高植物性蛋白飼料中添加肉鹼對龍膽石斑(Epinephelus lanceolatus)稚魚成長、體組成、肝臟氧化狀態、血液生化指標及脂質代謝之影響。實驗基礎飼料以大豆濃縮蛋白(SPC)取代50%魚粉蛋白並添加肉鹼0%、0.01%、0.03%、0.05%及0.1%，並以全魚粉組(FM)為對照組。含SPC之實驗飼料均進行離胺酸及甲硫胺酸的平衡。實驗飼料共六組，每組三重複，魚隻初重為19.50±0.03 g，實驗為期八週。實驗結果顯示，實驗飼料以高植物性蛋白取代魚粉蛋白後，添加不同含量之肉鹼，並不影響石斑魚稚魚成長表現、體組成、肝臟氧化狀態及血液生化指標。飼料添加肉鹼組與SPC+0%組相比有較高單元不飽和脂肪酸和較低EPA含量(p＜0.05)。肝臟長鏈脂肪酸(C20-C22)總量呈現下降趨勢，C14-C18脂肪酸總量則呈上升趨勢。FM組和SPC+0%組背肌與肝臟肉鹼濃度無顯著差異，而飼料肉鹼含量增加會提高肝臟與肌肉肉鹼濃度，但抑制肝臟肉鹼合成酵素(BBOX1)基因表現。結果顯示含高量SPC飼料添加肉鹼會增加長鏈脂肪酸的代謝。此外，肉鹼合成基因BBOX1表現量受實際飼料肉鹼量調控。本研究提出飼料中含充足的離胺酸含量，在石斑魚稚魚階段可合成肉鹼，但如果飼料中額外添加肉鹼則會降低BBOX1基因表現量。

關鍵字

龍膽石斑；肉鹼；大豆濃縮蛋白；成長；抗氧化；脂肪代謝；肉鹼合成與蓄積

並列摘要

The purpose of this study was to investigate the effects of carnitine supplementation in a high plant protein diet on growth, body composition, hepatic oxidative status, blood biochemical parameters and lipid metabolism in giant grouper, Epinephelus lanceolatus. The basal diet containing soy protein concentrate (SPC) that substituted to 50% fish meal protein was supplemented with 0%, 0.01%, 0.03%, 0.05% and 0.1% carnitine. All fish meal diet (FM) was used for comparison. Lysine and methionine were balanced in diets containing SPC. Total of six experimental diets were each fed to triplicate groups of juvenile grouper (initial weight: 19.50±0.03 g) in a recirculation system for 8 weeks. Growth, body composition, hepatic oxidative status and blood biochemical parameters were not significantly (p＞0.05) affected by dietary carnitine supplementation for the fish. Grouper fed diets supplemented with carnitine had higher (p＜0.05) monounsaturated fatty acids but lower EPA concentrations than fish fed the basal diet. Decreasing trend of total hepatic C20-C22 fatty acids and gamma-butyrobetaine hydroxylase 1 (BBOX1) gene expression, but increasing trend of C14-C18 fatty acids, dorsal muscle and hepatic carnitine concentrations were observed while dietary carnitine levels increased. Results indicate that dietary carnitine supplementation could accelerate metabolism of long-chain fatty acids. The carnitine synthesized gene (BBOX1) expression was regulated by actual dietary carnitine concentrations. This study suggests that carnitine can be synthesized in grouper juveniles fed the diet with sufficient lysine. However, the expression of BBOX1 gene would be suppressed in fish fed diets containing carnitine.

並列關鍵字

giant grouper (Epinephelus lanceolatus) ； L-carnitine ； soy protein concentrate ； growth ； antioxidant ； lipid metabolism ； carnitine synthesis and retention