Low protein deposit in Atlantic salmon

Atlantic salmon has less protein deposit due to high levels of plant proteins in fish feed, says a report.

It is observed that in a feeding trial, farmed Atlantic salmon were given feed with a high content of plant protein. Only 15 percent of the protein was marine protein. The results from the National Institute of Nutrition and Seafood Research (NIFES) show that less protein is deposited in the salmon when it is given feed containing high levels of plant protein.

It is also told that Atlantic salmon in salt water weighing around 640 grams were given either a feed containing mainly fish meal as protein source or a feed containing a high level of a plant protein mixture (85 % of the protein) with soy, wheat and corn gluten. Scientists informed that the plant protein feed also contained some fish meal, fish protein concentrate and squid, corresponding to totally 15 percent marine protein. The trial period was three months. Squid was added to the plant protein feed in order to enhance taste, but the salmon still ate less of this feed.

Researcher Ernst Morten Hevrøy at NIFES informed that the Atlantic salmon in this study seemed to adapt to the plant protein diet by an alteration in the growth hormones. He also said that they measured the gene expression of several growth hormones in the brain, liver and muscle. The growth hormones are naturally present in the fish` organs. There was a clear tendency towards down-regulation of the growth hormone IGF-I in white muscle, but not in the other organs.

Hevroy also said that it is therefore very likely that less of this hormone is produced when the salmon is fed a high proportion of plant protein. In our study, this resulted in 31% less protein deposited in the salmon.

It is informed that this study differs from previous ones in that both the control feed and the plant protein feed contained the same amount of the different essential amino acids and the same balance of fat, carbohydrates, proteins, trace elements and minerals, even if the raw plant material sources were different.

Source: nifes.no"

WorldFishingToday d. 13-03-2009