Effects of dietary astaxanthin supplementation on reproductive characteristics of rainbow trout (Oncorhynchus mykiss)

The effect of dietary astaxanthin supplementation on reproductive characteristics was investigated in five groups of female rainbow trout broodstock fed diets containing either 0.07, 12.46, 33.33, 65.06 or 92.91 mg astaxanthin kg(-1), respectively, and two groups of male rainbow trout broodstock fed diets supplemented with 0.07 and 33.33 mg astaxanthin kg(-1), respectively, for 6 months in an artificial photoperiod system until sexual maturation. The eggs from each group of female broodstock were divided into two equal batches. One batch was fertilized with homogenized sperm of four males fed diets with 0.07 mg astaxanthin kg(-1) and the other portion with sperm of four males fed diets with 33.3 mg astaxanthin kg(-1). The females produced eggs with astaxanthin concentrations ranging from 2.03 to 29.79 mg kg(-1). Dietary astaxanthin supplementation had positive effects on investigated reproductive traits. Significant differences in rate of fertilization, percentage of eyed and hatched eggs, and mortality of eyed eggs were found between treatments (P < 0.05), but no significant difference was found on percentage of mortality before hatching (P > 0.05). A significant difference (P < 0.05) in fertilization rate was found for male groups fed 0.07 and 33.3 mg astaxanthin kg(-1). The astaxanthin content in the eggs and fertilization rate, eyed-egg percentage and percentage hatch were significantly correlated (P < 0.05). It is concluded that dietary supplements of astaxanthin are required for optimum reproduction in rainbow trout.