The use of alfalfa, Medicago sativa as a natural carotenoid source in diets of goldfish, Carassius auratus

This study was conducted to evaluate the effects of diets including 0, 5, 10, 15, 25, and 40% alfalfa meals (containing 0, 20, 40, 60, 100, and 160 mg total carotenoids/kg diet, respectively) and 60 mg apo-ester, a synthetic carotenoid/kg diet on skin pigmentation, growth, feed utilization and survival of a red variety of goldfish, Carassius auratus, with average initial weight of 10.3 g, for a rearing period of 60 days. The pigmentation degree in skin of goldfish increased significantly with increasing inclusion of alfalfa up to 25% level in the diet (P < 0.05). However, the alfalfa inclusion over that level did not lead to more total carotenoid accumulation in the skin of fish. The diets including apo-ester and 15% alfalfa, both of which contained 60 mg carotenoid/kg diet, had similar effects on total carotenoid deposition in the skin of fish. Alfalfa addition of 25% or higher in the diet had an adverse effect on growth of fish compared to the control group (P < 0.05). A similar phenomenon was observed in feed conversion ratio but at the 40% alfalfa inclusion level (P < 0.05). However, no significant difference was observed in the survival of the fish. The present results demonstrate that alfalfa can be successfully used as an alternative natural carotenoid source to the synthetic apo-ester in goldfish diets. Our data indicates that 15% is a suitable dietary level of alfalfa to ensure good pigmentation, acceptable growth and feed utilization in goldfish. © 2008 Elsevier B.V. All rights reserved. SÜF 2002 BAP18 The authors would like to thank the Resource Fund of the University of Cukurova, (Turkey) for their financial support (with SÜF 2002 BAP18) of the experiment and Metin Kumlu and Mehmet Yücel for kindly revising the English of this paper.