Diet design By Dennis Smulders
N u trition al e mulsi f iers
make most of feed energy
With feed ingredient costs continuing to rise, supplementation with nutritional emulsifiers
can improve animal performance even with reduced feed energy intake.
The ability to digest lipids is not fully
developed in young animals. But several studies have demonstrated that
the supplementation of bile salts, lipase or
phospholipids to young animals improves
the digestibility of fats. These studies show
that lipid digestive processes are not fully
functional in young animals.
The amount of bile salts excreted by
the gall bladder is one of the key factors
influencing lipid digestibility in animals. The
emulsifying properties of bile salts enhance
fat digestion by reducing the size of the large
fat globules derived from the fatty part of the
feed. The efficacy of the lipase released in the
small intestine increases with decreasing fat
particle size. Furthermore, bile salts enhance
the formation of a micellar phase in the small
intestine which enhances fatty acid digestibility in dry diets (Bayler and Lewis, 1963). This
micellar phase transports the end products of
the fat digestion through the small intestine’s
membrane (Gurr and James, 1971).
When a shortage of emulsifying molecules
such as bile salts appears, fat digestibility will
significantly decrease. Freeman et al. (1968)
reported that in young pigs, the capacity of the
small intestine to absorb micellar lipid exceeds
normal influx into the gut. Therefore, entry of
fatty acids into the micellar phase limits fatty
acid digestibility (Bayler and Lewis, 1963).
Emulsifying agents promote the incorporation
of fatty acids into micelles. Augur et al. (1974)
and Polin (1980) reported increased digestibility of fat when an emulsifier was mixed with
the fat before it was fed to rats and chicks.
Increased digestibility
Nutritional emulsifiers mimick and fortify
the effect of the natural bile salts in poultry
and pigs. These nutritional emulsifiers are put
on a vegetable carrier to facilitate the use of
the product in animal feed formulations. The
inclusion of nutritional emulsifiers in broiler
and swine diets has been shown to result in
increased fat and feed digestibility.
A typical characteristic of nutritional emulsifiers is a low hydrophilic-lipophilic balance
(HLB). In contrast with technical emulsifiers
with a higher HLB, nutritional emulsifiers can
be highly soluble in the watery environment
of the intestine (Figure 1). To test the efficacy
of nutritional emulsifiers, a wide range of
scientific trials were conducted worldwide
in nursery, growing and fattening pigs and
in broilers.
Emulsification of fat (as in milk) may improve fat digestibility and growth performance
of animals fed supplemental fat. Jones et al.
(1992) reported an increase in fat digestibility
when emulsifiers were added to nursery diets
containing soybean oil or tallow, but not in
Figure 1. Nutritional emulsifiers in water environment
