Optimizing liquid fat blends with lecithin for feed efficiency

Soybean oil has long been the default liquid fat in compound feed, but it is not the only option. Whether they can do so has not been demonstrated across species and diets.

Lecithin is not a pure substance. It is a mixture of phospholipids such as phosphatidylcholine, glycolipids, triglycerides and other components, and its make-up depends on the source (soy, rapeseed or sunflower) and on processing such as degumming. In a feed, lecithin can play three different roles: as a separate additive, as a component of a compound fat raw material, and as part of an oil blend that replaces a conventional fat. This article looks at which factors determine the energy value and fat digestibility of such blends, and where the current evidence stops.

Cropenta Insight

For nutritionists and feed buyers, the key point is that an emulsifying effect and a higher fat digestibility are separate questions. Lecithin is involved in the physical conditions for digestion, but a blend that emulsifies well has not been shown to digest better in a given diet. Published broiler work reports digestibility and performance outcomes that depend on diet and age, so the triglyceride, free fatty acid and phospholipid content of each blend and its measured energy value should be checked before a soybean oil replacement is judged on paper.

Why emulsification matters for fat digestion

Fat is digested in the small intestine. Bile salts and phospholipids break fat into small droplets, which gives pancreatic lipase a larger surface to hydrolyse triglycerides into fatty acids and monoglycerides. These products form micelles that carry fatty acids to the intestinal wall. Better emulsification therefore favours the conditions for digestion, but it does not by itself prove that more fat is absorbed in a given diet.

Age matters. Young piglets and chicks produce limited bile salts and lipase, so their fat digestion is lower and improves as they grow. Saturated fats are digested less well than unsaturated oils in young animals, which is why fat source choice is more critical in starter diets than in grower or finisher rations.

What lecithin contributes, and what it does not

The EFSA evaluation of lecithins for all animal species concluded on safety for animals and consumers in the context of its use in animal nutrition, and reports no risk of irritation to skin and eyes for handlers.^[1] This safety assessment does not tell us how much a lecithin-containing fat contributes to energy supply.

In broilers, a 2025 publication on lecithin and lysolecithin as feed emulsifiers reports reductions in feed conversion ratio and an apparent improvement in nutrient digestibility.^[2] A 2023 broiler study of soybean lecithin added to diets containing fried soybeans examined growth performance, nutrient digestibility and serum profiles.^[3] Both are poultry studies, and their results depend on diet, age and the lecithin used, so they do not transfer directly to pigs, ruminants or aquaculture.

The energy value of a blend follows its components. Triglycerides supply most of the fatty acids for energy. Free fatty acids, which are more common in acid oils and by-products, are digested and absorbed differently. Phospholipids are amphiphilic and take part in emulsification, but they are not interchangeable with triglycerides in an energy calculation. Two blends may look similar on the label while differing in free fatty acid content, which the label alone does not show.

Blending saturated and unsaturated fats

Some reviews suggest that blending saturated and unsaturated fats may improve fat digestion, and that the two may respond synergistically.^[4] This is a plausible concept for formulation, but the evidence is suggestive rather than established. Its strength depends on the animal, the age and the ratio of fatty acids, and it should not be assumed for every lecithin-oil blend.

Energy value depends on the system used

Gross energy, digestible energy, metabolisable energy and net energy each subtract different losses from the energy in a fat. Values and systems differ between pigs, poultry and ruminants, and between national feed tables. Fats should be compared within the same system, with the same species and age, before a soybean oil replacement is evaluated.

Processing and storage observations

Unsaturated fatty acids are more prone to oxidation. Free fatty acids, metals and storage conditions reduce oxidative stability, and antioxidant content and storage practice help preserve it. Peroxide value and anisidine value are common indicators to request with a blend certificate. In mills, liquid blends that thicken at low temperature can be harder to dose and mix evenly, and uneven mixing shows up as variation in fat content between batches and sometimes as more fines after pelleting. These are practical observations rather than measured outcomes, and they depend on the specific blend and equipment.

Limits of the current evidence

Fish research cannot be transferred to other species without additional evidence. Where a blend is judged, its composition, energy value in one system, and oxidation status are the minimum information to request.

Technical Summary

Lecithin-oil blends can be evaluated as liquid fat raw materials in their own right. Their fat digestion and energy value depend on triglyceride, free fatty acid and phospholipid content, fatty acid profile, animal age and the energy system used. Emulsifying properties relate to digestion conditions but do not prove higher fat digestibility. Evidence in poultry is available, while evidence for other species and direct comparisons with soybean oil remains limited.

This article was created with the help of AI and reviewed by the Cropenta editorial team. It is general information, not professional advice.