Pigmentation of Rainbow Trout (Oncorhynchus mykiss) with Carotenoids from Marigold Flower (Tagetes erecta) and Red Pepper (Capsicum annum)


Abstract: The effects of diets including various natural carotenoid sources and synthetic astaxanthin on the pigmentation and growth of rainbow trout (Oncorhynchus mykiss) were investigated. Rainbow trout weighing about 111 g were fed diets containing 1.6%, 2.4% and 3.2% marigold flower; 4.4%, 6.6% and 8.8% red pepper; 100 mg kg^{-1} synthetic astaxanthin; and a control diet for 60 days. At the end of the experiment, synthetic astaxanthin provided the highest carotenoid accumulation in the fish flesh (6.42 mg kg^{-1}) in the groups. This was followed by red pepper (5.78 mg kg^{-1}) and marigold flower (5.59 mg kg^{-1}), each of which included equal levels (100 mg kg^{-1}) of carotenoids (P < 0.05). The fish fed marigold flower experienced yellow pigmentation, which was remarkably different from the other groups. An addition level of 2.4% or higher marigold flower and 6.6% or higher red pepper into the diet had negative effects on growth performance (P < 0.05). It can be concluded that the most appropriate dietary doses of marigold flower and red pepper for pigmentation of rainbow trout are 1.6% and 4.4%, respectively.

Keywords: Pigmentation, Oncorhynchus mykiss, red pepper, marigold flower

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