PHOTO: SHUTTERSTOCK


Hydrophilic head


Hydrophilic head


COVER STOR ▶▶▶Y


Figure 1 - The formation of a lysophospholipid (lysolecithin). As an example the formation of lysophosphatidylcholine from phosphatidylcholine is shown.


CH2 CH2


OO– O


P O


CH2 CH CH2 O


CO CO O


N1(CH2)3


Choline Phosphate


Phospholipase A2 Glycerol O


CH2 CH2


OO– O


P O


CH2 CH CH2 OH


CO


Phosphate Glycerol


N1(CH2)3 Choline


Nitrogen Phosphorus Oxygen Carbon Hydogen


Head (hydrophilic)


Fatty acid tails (hydrophobic)


LECITHIN


such as higher anti-nutritional factors, high level of carbohy- drates and lower nutrient densities. In literature it was men- tioned that accumulation of lipid droplets in the GIT of salmo- nids fed vegetable oils was repaired by the supplementation of phospholipids. This accumulation could be the result of a limited synthesis of phospholipids by the fish itself, and the lack of a well-developed pancreas as found in some teleost species. The pancreas produces phospholipase A2 which pro- motes the formation of lysophospholipids which are needed for an optimal fat emulsification. This indicates that a dietary emulsifier is needed. Scientific articles state that soybean leci- thin in feed improves emulsification and digestibility in the fish intestine. Next to these characteristics, phospholipids are also an important source of energy. Phospholipids tend to be a rich source of essential fatty acids and may be easier to digest than neutral lipids. Hence, products containing phos- pholipids and lysophospholipids are of interest for both fish meal/oil and vegetable oil based diets for aquatic species.


Importance of phospholipid profile To study the effect of different (lyso-) phospholipid profiles on performances of sea bass, a trial was performed in Greece. The European sea bass was used for this study and were ob- tained from a local fish farm. In total 270 fish were used and distributed over 9 cylinder-conical tanks of 0.170m3


in an


open flow water system (30 fish/tank). The trial lasted for 92 days. Three treatment groups were used which received the same commercial diet (45% protein and 18% fat, of which 11.8% added salmon oil and 2% added fish oil). The control group did not receive any additive; treatment group 1 re- ceived FRA® LeciMax Dry (trial product) with an inclusion rate of 750 gram/ton of feed. Treatment group 2 received a com- peting product that contains a smaller amount of lysophos- pholipids and was dosed at 750 gram/ton of feed. Both products were added on top of the basal diet. Feeding was


Head Fatty acid tail LYSOLECITHIN


performed close to satiation, twice a day (09:00H and 14:00H), six days a week. Water temperature was set at 25 ± 2 °C and oxygen concentration ranged from 5.4 – 6.7 ppm. At the end of the trial fish almost quintupled their weight (Table 1). The final weight of the fish in the control group was lower (76.6g) compared to the treatment groups (83.3g and 81.2g for treatment 1 and 2 respectively) in which the sea bass received lysolecithins. Moreover, the addition of lysoleci- thins resulted in improved feed efficiency (FE) and feed con- version ratio (FCR). Furthermore, these two parameters were only significantly better than the control group when the trial product was given (P=0.007 and P=0.013 respectively).


Conclusions From this trial it became clear that adding (lyso-) lecithin based products (750 g/ton) to the diet of sea bass containing 38.8% fish based raw materials and 56.2% vegetable based raw materials, resulted in better growth, FE and FCR. Feeding a product with a higher content of lysophospholipids resulted in the best performances.


Table 1 - Growth and feed utilization of sea bass fed different phospholipid supplemented diets during.


Control


Initial body weight (g) Final body weight (g) Weight increase (g) Feed Efficiency (%) FCR


Feed consumed (g/fish)


14.55 ± 0.15 76.56 ± 4.24 62.01 ± 4.09 81.18 ± 4.5a 1.23 ± 0.1a 76.54 ± 6.5


Treatment 1 14.64 ± 0.07 83.31 ± 0.98 68.67 ± 1.02 94.59 ± 1.2b 1.06 ± 0.01b 72.6 ± 1.12


Treatment 2 14.56 ± 0.17 81.16 ± 4.68 66.61 ± 4.6 86.38 ± 8.4ab 1.16 ± 0.11ab 77.58 ± 9.27


Values are means of 3 replicates accompanied by the standard deviation of the means. a,b Values without a common superscript within a row differ significantly (P≤0.05).


▶ ALL ABOUT FEED | Volume 25, No. 10, 2017 21


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