飼料中添加不同類胡蘿蔔素對紅頭金鯛之呈色影響

Abstract

本研究主要探討在飼料中添加不同種類及濃度的類胡蘿蔔素(Carotenoids)，對於紅頭金鯛的呈色之影響，評估色素代謝能力，並找出提升魚隻體色之最適添加量。前8週為呈色實驗，共採用二種不同的類胡蘿蔔素:玉米黃素(Zeaxanthin,以下簡稱Z), 蝦紅素(Astaxanthin,以下簡稱A), 而添加在飼料中的濃度與種類分別為0(control)、Z25、Z50、A25、A50、A75及A100(mg/kg diet)共計七組。第8-12週為褪色實驗。各組皆投餵不添加類胡蘿蔔素飼料，實驗後測定成長、色差計測量體色及分析魚體體表類胡蘿蔔素含量與組成色素。 本實驗結果指出在紅頭金鯛的飼料中添加類胡蘿蔔素對成長及飼料效率沒有影響。飼養8週後的呈色實驗結果顯示，飼料中添加類胡蘿蔔素的組別，平均色彩差異值（△E）可達8.4-10.1。魚體體表組織分析類胡蘿蔔素含量的結果以對照組最低，平均為1.3mg/100g。添加類胡蘿蔔素組別的魚皮總類胡蘿蔔素量為4.9-12.3mg/100 g隨著飼料中類胡蘿蔔素的增加而上升。第8-12週的退色實驗結果顯示，飼料中添加類胡蘿蔔素的組別平均色彩差異值△E值為8.5-11.2，魚體體表組織測定類胡蘿蔔素含量的結果以對照組最低，平均為0.8mg/100g，添加類胡蘿蔔素組別的魚皮總類胡蘿蔔素量為2.8-8.4mg/100 g。雖然由色差值的結果實驗組仍能維持與對照組的有差異，但由類胡蘿蔔素的含量之下降，顯示確實有褪色的現象平均下降率約為25-32%。Zeaxanthin與Astaxanthin的添加影響紅頭金鯛體色的呈色能力相近，且紅頭金鯛不能將玉米黃素有效轉換成蝦紅素，為使魚隻呈現黃色或紅色，建議使用玉米黃素或蝦紅素的添加量約32.4-35.5mg/kg。

This study focused on the different kinds and concentrations of carotenoid in diet, for effects of pigmentaion of giant cichlid (Pentenia splendida), assessment of pigment metabolism, and raise fish pigmentaion in the suitable amount. Experimental feeds are supplemented with two kinds of different carotenoid: zeaxanthin (hereinafter referred to as Z), astaxanthin (hereinafter referred to as A). The experiment period was total 12 weeks. In the pigmentaion experiments for the first 8 weeks, were divided into seven groups: control, Z25, Z50, A25, A50, A75 and A100 (mg/kg diet). In the dispigmentaion experiments for the last 4 weeks, all the groups were fed not add carotenoids diet. Fish skin were tested with tristimulus colorimeter, and further quantified for integument pigment. The experimental results indicate that the carotenoids have no effects on growth and feed efficiency, but improve pigmentation in the giant cichlid. In the pigmentaion experiments, the average color difference value (∆E) varied from 8.4-10.1, while the content of carotenoids in integument varied from 4.9-12.3mg/100 g. In the dispigmentaion experiments, the average color difference value (∆E) varied from 8.5-11.2, while the content of carotenoids in integument varied from 2.8 -8.4mg/100 g. Although the results of the experimental group by the color difference is able to maintain with control group differences, but by the decreased content of carotenoids shows that indeed fading phenomenon fell by an average rate of about 25-32%. The ability is similar in zeaxanthin and astaxanthin to affect the pigmentation in this species. The results indicate that 32.4-35.5mg/kg is a recommended dietary level of zeaxanthin or astaxanthin to ensure good pigmentation in the giant cichlid.