September 8, 2009

Nofima finds advantages with purified feed oil in salmon raising

New trials show that salmon fed feeds containing purified fish oil are healthier and have a firmer fillet, and that the feed is also utilised better, a result that should be included in the evaluation of whether or not it is profitable to use purified fish oil in salmon feeds.

Scientists at Nofima Marin have implemented the trials using Atlantic salmon on commission for Pronova BioPharma.

"The two feed types were identical apart from the fact that standard commercially available fish oil was replaced with the same oil purified in accordance with Pronova BioPharma's method," said scientist Jan Olli.

Results showed a trend of better growth and feed utilisation among salmon that consumed the feed containing purified oil. This was particularly the case during periods of high growth when both the growth rate and feed utilisation rate were significantly better for the fish that received the feed containing purified oil.

Another important finding was that the salmon that received the feed containing purified oil appeared to better tackle the handling stress during the slaughtering process - measured as a delayed pH reduction after killing. Other stress markers showed the same tendencies.

All the fish in the trial maintained a good red colour and firmness, but there was a tendency that fish that received the feed containing purified oil had a firmer texture. The difference in texture was most pronounced after freezing. The proportion of salmon with soft texture was then halved in comparison to the fish that received unpurified oil.