Dietary fat is the most energy-dense nutrient in feed. Its metabolizable energy is about 36.5 MJ/kg — more than 2.5 times that of starch-based ingredients. But adding fat to the formula does not guarantee that the animal absorbs it. In the gut, fat is insoluble in water and tends to form large oil droplets. Lipase can act only at the oil-water interface, so the available contact area is limited. Unabsorbed fat leaves with the feces and becomes one of the most overlooked costs in feed formulation.
Why Fat Is Difficult to Digest
The challenge comes from three basic facts. First, fat is energy-dense, so any loss is costly. Second, fat is insoluble in water, while the intestinal environment is water-based. Third, fat droplets have a limited surface area. Fatty acids and monoglycerides can only be acted on at the oil-water interface. Without emulsification, a large oil droplet offers a relatively small surface for lipase to work on. In practical terms, oil added to the feed is not the same as oil absorbed by the animal.
The Four-Step Fat Digestion Process and Where LPL Works
Using triglyceride as an example, fat utilization goes through four key steps: emulsification, enzymatic hydrolysis, mixed micelle formation, and absorption. Lysophospholipids mainly act in the first two steps and also support subsequent micelle formation. They reduce interfacial tension, help break large oil droplets into smaller and more uniform droplets, increase the area available for lipase, and work together with bile salts in the intestinal environment.
It is important to distinguish lysophospholipids from bile acid products. Bile acid products are more focused on micelle formation and supplementing the endogenous bile system. Lysophospholipids are more focused on rapid adsorption at the oil-water interface, reducing interfacial tension, and stabilizing small lipid droplets. The two act at different points and are not replacements for each other. Bile itself relies on both bile salts and phospholipids to complete emulsification and solubilization. Supplementing lysophospholipids is essentially supplementing the phospholipid part of this natural system.
Bile Salts vs. Lysophospholipids: A Practical Comparison
Inside the Emulsifier: LPL 10%, LPC ≥3%
Sustar’s lysophospholipid emulsifier contains 10% lysophospholipids (LPL), of which lysophosphatidylcholine (LPC) is ≥3%. The raw material is soy lecithin modified by enzymatic treatment. Natural soy lecithin has two fatty acid chains, which makes it more lipophilic and limits its emulsifying capacity in the water phase. Enzymatic modification removes one fatty acid chain, producing LPC with improved hydrophilicity, a higher HLB value, and a lower CMC. This allows it to spread more effectively at the oil-water interface and stabilize small lipid droplets.
Product specification: light brown to brown powder; LPL 10%; LPC ≥3%; moisture ≤12.0%; packaging 25 kg/bag; shelf life 24 months.
Structural differences between soybean lecithin and lysophosphatidylcholine
Other emulsifiers: larger oil droplet size
This product: oil droplets are small and uniform.
Differences in Emulsion Stability Observed After Homogenization and Subsequent Standing
When Endogenous Emulsification Is Not Enough
In three situations, the animal’s own emulsification capacity may not keep up with dietary fat. First, young animals such as piglets, young poultry, and fish or shrimp larvae have limited bile and lipase secretion. Second, high-fat diets can exceed endogenous emulsification capacity. Third, long-chain saturated fats have higher melting points, are harder to disperse, and may form insoluble soap salts with calcium. Other factors such as oxidized oil, excessive heat treatment, liver and pancreas function, and gut microbial status can also affect fat digestion and absorption. In these cases, supplemental emulsifiers can help improve fat utilization.
Application and Recommended Inclusion
| Total dietary fat (%) | Inclusion (g/t) |
|---|---|
| 3–5 | 100 |
| 5–7 | 150 |
| 6–8 | 200 |
| 8–10 | 250 |
| >10 | 300–400 |
If adjusting by added oil ratio, a practical reference is: 1–2% added oil → 100 g/t; 2–4% → 200 g/t; 4–6% → 250 g/t; >6% → 300 g/t. Actual inclusion should be adjusted according to fat source, animal stage, formula cost target, and field conditions.
From Interface to Formulation Value
The value of a lysophospholipid emulsifier can be understood through a simple chain: smaller lipid droplets create a larger oil-water interface; a larger interface gives lipase more room to work; more efficient hydrolysis supports better fat absorption; and better fat absorption means less oil is excreted and more room is released in formula cost. For feed producers, this is not only a technical improvement at the interface — it is a practical way to review the true cost of dietary fat.
Lysophospholipids do not replace bile acids. They complement the phospholipid fraction of the animal’s natural emulsification system. By working at the oil-water interface and supporting bile salt synergy, they help convert added oil into absorbed energy.
Want to review your fat source and inclusion rate? Contact Sustar for a formulation review or sample evaluation of our lysophospholipid emulsifier.
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Post time: Oct-20-2026
