Lysolecithins have proven to be a cost effective solution to improve fat emulsification and consequently fat digestion and nutrient absorption in broilers. The cost of broiler production will be lower either due to the lower feed intake or due to feed reformulation replacing expensive fat sources by cheaper grains.
Over the years broiler breeders managed to improve the genetic potential of broilers to grow fast and reach higher final body weights. Optimal farm management and high energetic feeds should make it possible for the broilers to grow towards their genetic potential. In order to formulate high energetic diets, high inclusion rates of fat are used. For optimal fat digestion, fat needs to be emulsified by the phospholipids contained in the bile acids. However, young broilers are known to have a bile acid deficiency. Bile acid concentration in the jejunum was found to decrease during the first week of life and increase in the second and third week. Even at 42 days of life, the bile acid concentration seems to continue to increase. This may suggest that at the moment of slaughter the bile acid concentration still did not reach its optimal level. Where genetic modulation of modern breeds succeeded to develop broilers that eat a lot and grow fast, they were not able to adapt their physiology in general and the bile acid excretion more particularly.
To overcome the problems with high fat diets and low bile acid excretion, phospholipids can be added to the feed. However, the gastro-intestinal tract is an aqueous environment and thus an emulsifier is required that promotes an ‘oil-in-water’ emulsification. This requires phospholipids with a higher hydrophilic-lipophilic balance (HLB-value) and therefore these phospholipids must be hydrolysed to lysophospholipids.
Lecithin is a complex mixture of phospholipids, some oil, glycolipids and carbohydrates. Lecithins are naturally occurring in plant and animal tissues. The phospholipids in lecithins have an amphiphilic character, meaning the molecule has both hydrophobic and hydrophilic characteristics. This can be explained by the molecular structure, which consists of two hydrophobic fatty acid tails and a hydrophilic phosphate head, joined together by a glycerol molecule. These so called native lecithins are by-products from the oil refinery and usually applied in animal feed as a relatively cheap energy source.
In contrast, lysophospholipids, also known as lysolecithins, are better known for their strong capacities of promoting an oil-in-water emulsification. These lysolecithins are obtained by hydrolysis of a native lecithin by the action of the enzyme phospholipase A2. The hydrophobic fatty acid at the C2 position of the glycerol molecule is removed by the action of this enzyme. The obtained lysolecithins have a more hydrophilic character and a higher HLB-value than native lecithins.
FRA LeciMax Dry, produced by Framelco, contains high amounts of hydrolysed soy lecithins. Hydrolysed soy lecithins have good levels of the more specific lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE). LPC and LPE are both important components of the lipid bilayer of cell membranes and increase their fluidity and consequently the absorption capacity of the intestinal epithelium cells.
Lysolecithins have the particular ability to improve fat digestibility, but also to enhance general nutrient absorption. Therefore, lysolecithins can either be added ‘on top’ without changing the composition of the diet or feeds can be reformulated with lysolecithins using a nutritional matrix.
Applied on top
When lysolecithins are applied ‘on top’, feed conversion ratio (FCR) is clearly improved and growth rate is maintained or increased. In Germany, a farmer tested the product. Six houses with in total 103,000 broilers were used during the trial. Three houses (51,500 broilers) were kept as control group and three houses (51,500 broilers) as treatment group. Both groups received the same diet. The product was added on top with a dose level of 500 grammes per ton of feed.
All broilers had a start weight of approximately 40 grammes. Final body weight was not different between the groups (2.53 kg versus 2.52 kg for the control and treatment group respectively). However, feed intake was reduced in the treatment group resulting in a 6 point lower FCR. Also, mortality in the treatment group was lower (see Table 1). This might suggest that improving fat emulsification in a wheat-based diet allows the NSP-enzymes to lower the digesta viscosity more efficiently, which results in a better health status of the animals as there is less opportunity for pathogenic bacteria to grow. Moreover, the application of the lysolecithin based product showed to be very cost effective, as the return on investment (ROI) was 7.
As a result of better fat emulsification, more efficient enzymatic hydrolysis of fat will take place which results in better fat digestibility and absorption. Moreover, LPC and LPE increase the membrane fluidity of the epithelium cells and consequently enhance nutrient absorption in general. Consequently, more dietary energy and more amino acids from the feed become available for the animal. In other words, one may lower the energy and amino acid levels in feed, maintaining the same performances. Therefore, reformulating the diet when using the product, may be a very interesting and cost effective application. A rather simple way of reformulating the diet is by replacing 1% of the added oil or fat by grains (wheat or maize) and add 500 grammes of the product per tonne of feed. The effect of this reformulation was tested at a broiler research facility in the Netherlands. In total three groups of six birds with 11 replicates were used. The control group received a regular diet with a crude fat content of 4.9% in the starter diet and 8.0% in the grower/finisher diet. In the ‘low fat diet’ 1% of soybean oil was replaced by 0.5% wheat and 0.5% maize. The third group (treatment) received the same ‘low fat diet’, but then 500 grammes of the lysolecithin based product was added per tonne of feed.
General performance parameters were improved by the lysolecithin based product (Figure 1) despite the fact that due to the lower fat content the metabolisable energy of the treatment diet was 1.7% lower compared to the control group. Also, the low fat diet including the product was cheaper than the control diet.