飼料中添加不同濃度與來源之類胡蘿蔔素對珍珠鱗金魚增豔效果之影響

Abstract

珍珠鱗金魚 (以下簡稱珠鱗 )，英文俗名 pearlscale goldfish 為金魚的一種，只需保持水體清潔即可飼養，因此在觀賞魚市場具有相當高的經濟價值 。 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對於珍珠鱗金魚的呈色和色素代謝之影響。在飼料中採用兩種不同的類胡蘿蔔素：玉米黃素(Zeaxanthin，以下簡稱Z)，合成蝦紅素(Synthesis Astaxanthin，以下簡稱S)，其添加在飼料中的濃度與種類分別為0(control)、Z-5、Z-10、Z-15、Z-20、S-5、S-10、S-15、S-20(mg/kg diet)共計九組。試驗用魚種珍珠鱗金魚，馴養四星期，馴養期間投餵不含類胡蘿蔔素的飼料，以免在馴養期間攝入類胡蘿蔔素而影響實驗，並於分組試驗前一天絕食。隨機取樣魚體平均體重2.69±0.23g的每組8尾珍珠鱗金魚，每組固定有一隻白色體色的珠鱗為盲點對照組，飼養於長*寬*高為45*30*30cm配有上部過濾的水缸共計9組。 經7星期飼養珍珠鱗金魚後各組間的活存及平均增重0.94g成長無顯著差異。結果顯示呈色添加合成蝦紅素的組別與添加玉米黃素的組別有顯著差異，隨著合成蝦紅素的濃度升高而有增高的趨勢。合成蝦紅素的添加影響珍珠鱗金魚體色的呈色效果較玉米黃素為佳，並以15mg/kg為最適添加量。

This study focused on the different kinds and concentrations of carotenoid in diet, for the effects of pigmentation of pearlscale goldfish (Carassius auratus), assessment of pigment metabolism, and raise fish pigmentation in the suitable amount. Experimental feeds are supplemented with two different carotenoid: zeaxanthin (hereinafter referred to as Z), synthesis astaxanthin (hereinafter referred as S). Experiment period was total 7 weeks, mean weight of pearlscale goldfish was about 2.69g. Experimental diets were divided into 9 groups: control, Z5, Z10, Z15, Z20, S5, S10, S15 and S20 (mg/kg diet). Fish skin were tested with tristimulus colorimeter, and further quantified for integument pigment. Results shows that the addition of carotenoids have no effects on growth and feed efficiency, but improve the pigmentation by enhanced a and b values in pearlscale goldfish. The coloration of both S groups and Z groups were increase by the raising of concentrations of carotenoid in diet. Therefore, we can say that synthesis astaxanthin is more effective than zeaxanthin in the addition of carotenoids in diets for pearlscale goldfish, and the optimal concentration is 15mg/kg diet.