Replacement of carrot powder with synthetic astaxanthin in the rainbow trout diet: effect on the growth performance and blood parameters

In this study, replacement of carrot powder with synthetic astaxanthin (SA) in the rainbow trout diet was examined by some growth parameters (final weight, specific growth rate, condition factor, protein efficiency ratio (FCR), food conversion ratio and daily food intake) and blood indices (cortisol, glucose, total protein, alkaline phosphatase, alanine aminotransferase, asparate aminotransferase and lysozyme). For this purpose, 6 diets including control (no replacement), diet with 100% astaxanthin (at 100 mg/kg of diet) and four diets with partial and total replacement of SA by carrot powder (25, 50, 75 and 100%) were prepared. Growth performance indicated that replacement of SA by carrot powder caused effect on the weight gain and specific growth rate (p<0.05). With the increase of carrot powder in the fish diet, weight gain increased and FCR more reduced. The best results were obtained in the treatment that carrot powder replaced over 75% in the diet. Therefore, replacement of SA with carrot powder is fully possible in the rainbow trout diet.