Tag: Flesh color

Reports

Use of canola oil in winter feed for salmon in the sea / Use of canola oil in winterdiets for Atlantic salmon

Published:

01/02/2014

Authors:

Jón Árnason, Jón Örn Pálsson, Gunnar Örn Kristjánsson, Ólafur Ingi Sigurgeirsson, Arnþór Gústafsson

Supported by:

AVS fund reference no. R 089‐12

Use of canola oil in winter feed for salmon in the sea / Use of canola oil in winterdiets for Atlantic salmon

An experiment was performed with different amounts of rapeseed oil (0, 50 and 80%) in winter feed for 570 grams of salmon raised in the sea with 28.2 ‰ salt (26 - 34 ‰) at an average temperature of 4.5˚C (3.8 - 5 , 6˚C). The fish doubled in weight during the 152-day trial period. TGC3 was an average of 2.9. The fat content of the feed had very little effect on the growth, feed intake, feed utilization and volume content of fish fillets. The composition of the feed fat did not have much effect on the color of the fillets, although fish that were fed only fish oil gave significantly (p = 0.017) lighter fillets than fish that were fed with rapeseed oil. The type of fat in the feed, however, had a significant effect on the fatty acid composition of the fat in both the feed and the fat in the fillets, especially the EPA, DHA content and the ratio of n-6 and n-3 fatty acids. However, the results show that the effect in the fillet fat is much smaller than in the feed fat, especially with the fatty acid DHA. It seems that DHA converts feed fat into fillet fat rather than using it as an energy source.

An experiment with different inclusion of Canola oil (0, 50 and 80%) in diets for 570 grams Atlantic salmon that was reared in sea water with average salinity of 28.2 ‰ (26 - 34 ‰) at average temperature of 4.5˚ C (3.8 - 5.6˚C). The fish doubled its weight during the 152 days trial period. TGC3 was on average 2.9. The fat type had had only minor effects on growth, feed intake, feed conversion and nutrient content in filet. The fat type in the diet did not have much effect on the filet color even though the fish that got feed with fish oil was significantly (p = 0.017) lighter in filet color than fish that got diets with Canola oil. Composition of the diets had market effect on the fatty acid composition of both dietary fat and filet fat in particular the content of EPA and DHA and the n ‐ 6 to n ‐ 3 ratio. However the results show lower effect in the filet fat than in the dietary fat, particularly regarding the content of DHA indicating that the fish is directing that fatty acid towards the storage lipid in the filet rather than using it as energy source.

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Reports

Coloring of Arctic charr / Coloring of charr hold

Published:

01/05/2011

Authors:

Jón Árnason, Ólafur Ingi Sigurgeirsson, Gunnar Örn Kristjánsson, Jón Kjartan Jónsson, Turid Synnøve Aas and Trine Ytrestøyl, Manfred Phiscker

Supported by:

Technology Development Fund

Coloring of Arctic charr / Coloring of charr hold

An experiment was carried out with the aim of evaluating the activity of an organic pigment, Ecotone ™, and an inorganic pigment, Lucantin® Pink, on the coloration of char meat. The effect of 25% and 30% fat in feed on the activity of the pigments was also studied. All experimental items were tested in triplicate. The mean weight of the experimental fish was 564 g at the beginning of the experiment and 1381 g at the end of the experiment after 131 days. The temperature during the experimental period averaged 8 C̊ and the salinity of the broth was 20 ‰. The digestibility of astaxanthin in Lucantin® Pink was much higher than in Ecotone ™. The difference in body color measured by different methods turned out to be much smaller, which indicates a better utilization of the color in Lucantin® Pink. Little effect on body coloration was found by different amounts of fat in the feed and this was true for both pigments. The organic dye is more expensive to buy than the inorganic one and it results in approx. 5.5 % is more expensive to dye char with Ecotone ™ compared to Lucantin® Pink. During the analysis of the color of the feed at the beginning and at the end of the experiment 16 weeks later, it was found that there was a significant loss of color from the feed and that loss appeared to be independent of the type of color.

A feeding trial was conducted to compare the pigmenting efficiency of the biological colorant Ecotone ™ containg astaxanthin and prepared from the red yeast Phaffia rhodozyma, and the synthetic colorant Lucantin® Pink in Arctic charr. Both colorants were incorporated into diets containing either 25 or 30% lipid. All treatments were run in triplicate. The initial average weight of the fish was 564 g and the final weight 1381 g after a trial period of 131 days at 8 C̊ and 20 ‰ salinity. The digestibility of astaxanthin seems to be very much dependent upon the astaxanthin source. Differences in flesh color indicate a better utilization of astaxanthin from the synthetic source (Lucantin® Pink) as compared to the biological source (Ecotone ™). There was only a minor effect of lipid content on utilization of the astaxanthin. The biological astaxanthin source is more expensive than the synthetic source, resulting in about 5,5% higher production cost of fish produced with the “organic” colorant Ecotone ™ as compared to fish produced with the synthetic source of astaxanthin (Lucantin® Pink). The astaxanthin content in all diets proved to be very unstable when the feed was stored under conditions that are common in production of Arctic charr (10 - 20 ̊C indoors). The loss of astaxanthin ranged from 21-40% and tended to be higher in diets containing Ecotone ™. Thus, it is very important to avoid high temperatures, light and oxygen during storage of the feed.

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