Nghiên cứu ảnh hưởng của việc bổ sung Astaxanthin và β – glucan được chiết xuất từ sinh khối nấm men <i>Rhodospridium</i> sp. Vào thức ăn cho cá dĩa đỏ <i>Symphysodon</i> sp.

Abstract

    The study was aimed to evaluate the effects of astaxanthin and β-glucan extracted from yeast biomass Rhodospridium sp. as the food supplement for Red Discus Symphysodon sp. The first experiment examined the effect of astaxanthin supplement in food to enhance the color of Red Discus fish from (around) 6cm in size. The experiment had three treatments: (1) Food supplemented with extracted astaxanthin 90 mg/kg; (2) Food supplemented with astaxanthin from the market with 90 mg/kg dose; (3) Normal food without astaxanthin. After 90 days of the experiment, the result showed that Red Discus in treatment 2 had the darkest color, followed by treatment 1 and the lowest was the control. Although fish in treatment 1 had lighter color than fish from different treatments, the color retained long after the feeding with pigmented food had been stopped in comparison with Red Discus in treatment 2. Moreover, astaxanthin extracted from yeast biomass had the effect on improving the color of Red Discus. The second part of the experiment included investigating the effect of the supplement of β-glucan on feed to enhance the immunity in Red Discus Symphysodon sp. with the size around 6cm per individual. The experiment consisted of 3 treatments with β-glucan supplemented in the food for 30 days with doses of 0.1%, 0, 5% and 1%, respectively with the control was the food without β-glucan. After 30 days, the results illustrated that the feeding diet with 1% β-glucan supplement was able to stimulate the immune system of Red Discus through the white blood cell concentration more than 3500 cell/ul. Besides, β-glucan could improve the immune system of the fish rather than cures the diseases.

Key words: astaxanthin, red discus, yeast biomass Rhodospridium sp, β-glucan.