Krill diet ‘improves sea bream survival’

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Sea bream larvae fed on a diet including krill show increased survival rates and enhanced growth. The findings come from a study by researchers at KAUST (the King Abdullah University of Science and Technology, Saudi Arabia, the Institute of Aquaculture at Stirling University, Scotland and Universidad de Las Palmas de Gran Canaria, Spain.

The larvae were fed a diet including 7% krill phospholipids (marine lipids which contain omega-3 fatty acids) and their performance was compared with another group on a diet featuring soybean lecithin lipids.

Reda Saleh Azam, Senior Scientist at KAUST, said: “The high survival rates and greater growth in the larvae fed seven percent krill oil phospholipids shows that inclusion of krill in the feed ensures more of the important fatty acids are being absorbed and utilised by the fish. This is in line with previous research that shows that the phospholipid source is important, and krill oil phospholipids are consistently more effective in terms of health, growth and overall survival in fish.”

Omega-3 fatty acid composition in the body was highest in the larvae fed 7% and 9% krill oil phospholipids, the study found. The larvae fed the soybean lecithin and control diets exhibited significantly higher presence of large vacuoles of lipid droplets in the liver and intestine, indicating poor utilisation of the dietary lipids.

The krill-based lipids were provided by Aker BioMarine. Andras Ziener, VP Business Development, Animal Health & Nutrition with the company said: “The researchers found that by including just seven percent krill oil phospholipids in the seabream diet, the larvae exhibited enhanced growth and survival, along with significantly less lipid (or fat) deposits in the intestine and liver, as compared to fish consuming the soybean lecithin diet.”

Both krill oil and soybean lecithin are dietary sources of phospholipids, which is an important source of energy in fish, particularly during embryonic and early larval development. Phospholipids possess a high content of omega-3 fatty acids that are easier to absorb and digest, in addition to its feed attractant properties that support better diet quality in fish. Previous studies have also show that phospholipids provide inositol and choline, which are important for increasing the absorption of nutrients.

The study, titled Different phosphatidylcholine and n-3 HUFA contents in microdiets for gilthead seabream (Sparus aurata) larvae: effects on histological changes in intestine and liver, was authored by Reda Saleh, Monica Betancor, Asaad Hassan Mohamed, Tamer El-Sayed Ali and Marisol Izquierdo was published in the journal Aquaculture International.