Plant raw materials in charr feed instead of fishmeal and fish oil
The aim of the project was to produce cheap feed for char so that production costs can be reduced and profitability in char farming can be increased. The project consisted of testing different raw materials (especially plant raw materials) instead of fishmeal and fish oil and finding out how large a proportion of them can be in the feed. The condition for success was that the feed was healthy, utilized well by the fish and led to a growth comparable to the current farmed feed and that the feed did not have a negative effect on the quality of the product, in terms of chemical content (fatty acid, color) and physical properties (taste, color, density). Different types of feed were tested as a starter feed for charr juveniles, which is a new approach, in order to get an overview of the possible amount of different raw materials. The most interesting types of feed from those experiments were then tested in experiments on larger chars to confirm the results and to examine the effect on the quality of the products. The results of the experiments with different protein ingredients confirmed that high quality fishmeal (Superior) is a very good source of protein in feed for char. The charr's possibilities of utilizing soybean meal seem to be limited, as in the case of salmon, ie. ≤ 15% incorporation into the feed. The possible use of maize gluten meal appears to be ≤ 18% in starter feeding but could not be tested on larger fish. The reaction of char to rapeseed meal as a protein source, however, was positive and in fact better than expected considering that there has not been a good word for this raw material in feed for other salmonids. Regarding fat sources in charr feed, the results of the project show that different fat sources can be used with acceptable results. Juveniles, on the other hand, seem to have somewhat stricter requirements for fat sources than larger fish. This is especially evident in the effect on growth rate. The results of the experiments with fat sources also show that the composition of the fat source has a decisive effect on the fat composition of the fish as well as various sensory evaluation factors in the product. The main conclusion, however, is that it is possible, within certain limits, to use different fat sources in charr feed. In particular, it seems that palm oil can be used extensively.
The objective of the project was to produce economic feed for Arctic charr to decrease production cost and increase profitability in Arctic charr farming. The project investigated the possibilities of replacing fishmeal and fish oil with raw materials of plant origin, and to find out the limits for their use as feed ingredients. The criteria was that the feed should ensure maximum health, optimize utilization of feed and growth should be comparable to growth obtained by feed currently used. Neither should the feed have adverse effects on product quality, especially regarding fatty acids composition and physical properties (taste, flesh-color, texture). Effect of different raw materials was screened in start feeding trails using Arctic charr larvae. The most interesting raw material combinations were thereafter tested in trials with bigger fish in order to confirm the results of the start feeding trials and investigate the effect of the combinations on slaughter quality of the Arctic charr. The results of the trials with different protein raw materials confirmed that high quality fishmeal (Superior) is a very good protein source for Arctic charr. Arctic charr seems to have limited ability to utilize soybean meal and the inclusion should be limited to ≤ 15% in the diet, similar to the limits that are common for Atlantic salmon diets. The limits for use of Corn gluten meal in starter diets seem to be ≤ 18% but this raw material was not tested in bigger fish. The response of Arctic charr to the use of rapeseed meal as a protein source was positive and even as high inclusion as 30% in the diet did not have negative effect on growth. The main findings of the project regarding use of lipid sources is that it is possible to use different sources with reasonable effect in feed for Arctic charr. Of particular interest is the effect of palm oil. Arctic charr larvae seem to be more demanding, regarding use of lipid sources, than bigger fish. The results clearly demonstrate the effect of fatty acid (FA) composition of the lipid sources on the FA composition of the fish and it is possible to change the FA profile with different lipid sources. Different lipid sources also have marked effects on different sensory traits in the farmed Arctic charr.