AQUACULTURE STUDENT

FIONA DARKIN

What They Did Back Then

* Master of Science in Aquaculture completed 1996, University of Guelph

Advisor: Professor Richard D. Moccia

Pigmentation of Arctic charr ( Salvelinus alpinus) Fed diets containing varying levels of Astaxanthin.

ABSTRACT

Four dietary levels of astaxanthin, (0,40,80 and 120 mg kg-1 ) were fed to three replicate groups each of Arctic charr, Salvelinus alpinus (Labrador strain), which has not previously received supplemental dietary carotenoids. The growth and flesh pigment scores were monitored at 4-week intervals over a period of 20 weeks. Growth was monitored by establishing the tank weights and dividing this value by the number of fish in the tank. The weights of the fish in the separate treatments were not significantly different (P< 0.05) throughout the period of the trial. Pigment scores were evaluated subjectively using the Roche Colour Card for salmonids. A sample, pooled across treatments, gave a base-line score at week zero of 1.28. The pigment scores of the control group decreased significantly during the trial to 0.13 (week 20); those of the 40 mg kg –1supplemented group increased significantly to 2.01 (week 20); the 80 mg kg group increased significantly to 2.88 (week 20 ) and the 120 mg kg group increased significantly to a high of 2.90 (week 16). Throughout the trial, the pigment scores of the 80 mg kg and the 120 mg kg did not differ significantly. There was a high degree of variation within the treatment groups. Individual fish were not identifiable so it is not known if this variability could be attributed to a difference in feed intake (and therefore a difference in the amount of dietary carotenoid received) or other factors. The results of this investigation indicate that supplemental pigmentation levels of 80 mg kg give the highest pigment scores over a 20-week period. There does not appear to be any benefit to higher inclusion. Recommendations are included to provide farmers with a guideline for pigmentation program.