The AVS project "Interaction of fat and pigment in feed on the growth and quality of Icelandic char" has been completed and has final report of the project now been released. The objectives of the project were twofold: a) to evaluate the effect of fat content in feed on growth, feed utilization and quality of char, b) to find the most efficient way of using and utilizing pigment in feed and its interaction with fat content in feed and fish. But with that, it would be possible to achieve significant savings in charr farming.
The project carried out long-term growth experiments with char, where the effects of feed on growth and important quality factors in char, fat composition and body color were investigated. The first objective of this study was to investigate the effect of different fat sources and fat content in feed on the growth and chemical composition of fillets. The second objective was to investigate the effect of different pigments in the feed and different pigment feeds, during the production period, on the flesh color of the fillets. The project was carried out in collaboration between Íslandsbleikja, Matís, Hólar University and the LAXÁR Fodder Factory.
The experiments showed that different fat content of feed and different fat raw materials did not affect growth, growth rate, feed consumption, feed utilization of FCR or utilization factors at slaughter. The fat content of the feed, on the other hand, was reflected in the fat content of the fillets and the fatty acid composition of the feed was in most cases clearly reflected in the fatty acid composition of the fillets. Different fat ingredients and fat content in the feed had little effect on the visible flesh color in the fillets. Greater color variability became more pronounced when pigments were chemically analyzed in fillets.
Analysis of the concentration of pigments in the experimental feed showed difficulties in the production of feed with an exact color content, according to the plan and feed recipes, regardless of the color of the dyes or in improved quantities. There was a significant loss of feed color, in feed production, when using organic coloring, and this loss appeared independent of admixture. The results indicate that these processing losses (approximately 30%) need to be taken into account to ensure that the fish receives sufficient pigment for normal carcass coloration.
Different pigments and different pigment concentrations had no significant effect on the growth rate of feed utilization or the nutritional content of the fish.
A small difference was detected in visible color (Salmofan), but fillet color measured by Minolta analysis showed more correlation in the color of fillets and eaten pigments. The chemical analysis of fillets in fillets was correlated with the amount of pigments eaten. The concentration of pigments in the feed in excess of 50 mg / kg had no visible effect towards a redder flesh color in the fillets.
They provide more information about the project Jón Árnason at Matís and Ólafur Ingi Sigurgeirsson at Hólar University.