Short Review on "Role of Emulsifier's in Poultry Diet" By Dr.Sanjay Gapat , Sr.Product Manager, PMT-Alivira Poultry

Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Fats may be either solid or liquid at normal room temperature, depending on their structure and composition. Although the words "oils", "fats" and "lipids" are all used to refer to fats, "oils" is usually used to refer to fats that are liquids at normal room temperature, while "fats" is usually used to refer to fats that are solids at normal room temperature. "Lipids" is used to refer to both liquid and solid fats. Fats or lipids are broken down in the body by enzymes called lipase produced in the pancreas.

?         Fats are digested in Two steps

–        Emulsification

–        Lipase Action

Emulsification

Bile released by gall bladder (bodies natural emulsifier) allows the fat to mix with water by breaking the fat into smaller droplets. This is called Emulsification.

Lipase Action

The digestive enzyme Lipase breaks each fat molecule into the smaller glycerol and fatty acid molecules

Fat emulsification in the digestive tract occurs with the help of the bile salt and this is followed by fat digestion with the help of lipase. The emulsion in the digestive tract is oil in water emulsion (O-W), and lipase works only in the O-W emulsion. The most critical step in fat digestion is the digestion of > C14 fatty acids (FA) and it is the > C14 FA which need to be emulsified.

Why an emulsifier is needed?

Poultry feed consists nutrients in the form of carbohydrates, proteins and fats. Carbohydrates and proteins are easily dispersed, dissolved in water and are easily digested. But in case of fat, its digestion occurs mainly in small intestine of bird and emulsification of fat is only possible by bile which acts as bio-surfactant. Bile secretion contains bile salts, cholesterol and phospholipids. This process enables lipase enzymes to break the fat into diglycerides, monoglycerides and fatty acids. Some of the factors that require emulsifier are as following.,

1. In case of young birds: It is generally known that young birds have limited ability to digest fats which is due to limited bile salt secretion and absorption (entero-hepatic circulation), which is result of its immature digestive capacity which still matures with age.
2. In case of infection: Pathogenic organism affects intestinal epithelium. Epithelial cells are ruptured by which absorption capacity is reduced and impaired fat absorption.
3. In case of cereals having high levels of NSPs (non-starch polysaccharides): These have strong anti-nutritional activity. They increase the viscosity of digesta in chicken intestine. Increased viscosity leads to inadequate absorption of nutrients, impaired peristaltic progress of chyme through intestine which leads to bacterial overgrowth. This eventually can lead to loss of conjugation of bile salts by the microflora in the upper intestinal tract, which immediately will result in a reduction of fat utilisation.

Rate of bile secretion is the main reason why fat digestion does not occur properly at an early age. The problem is confounded by the following facts:

-         Bile salt gets de-conjugated by bile salt hydrolase, bacteria like Enterococcus faecium and Clostridium and by lipase,

-         Insufficient recirculation and re-absorption of bile salts.

Critical miceller concentration (CMC)

For proper emulsification to occur level of bile salt/emulsifier should be greater than the critical miceller concentration (CMC). CMC means the concentration of the surfactants above which micelles form and all additional surfactants added should go into the micelles. So, external emulsifiers are needed especially at an early age (first 2 weeks of age).An emulsifier is amphipathic in nature having both hydrophilic and hydrophobic parts.

Hydrophilic-Hydrophobic Balance

The extent to which the parts of an emulsifier are hydrophilic and hydrophobic (lipophilic) in nature determines the HLB value.

·        Hydrophilic-Hydrophobic Balance Value

·        This is a concept for choosing emulsifiers

·        Low HLB emulsifiers are soluble in oil while high HLB emulsifiers are soluble in water

-         Lower HLB: more lipophilic

-         Higher HLB: more hydrophilic

The HLB determines which type of emulsifier should be used. In O-W emulsion (as it is there in the gut) a high HLB is required.

Role of emulsifier:

In commercial poultry industry, high energy yielding ingredients fats and oils are added. Oil is added as it is relatively cheap source of energy than other carbohydrates sources. This gives better FCR in broilers and enhanced productivity in layers and breeders. As we know younger birds utilise fat poorly due to less bile salt production. So, emulsifier from outside source is needed. Phospholipid, Hydrolysed lecithin, Lysophospholipids, Phosphatidyl choline, are commonly used components as an emulsifier.

Lipized DS :Double Strength Balanced Emulsifier -Breaks the fat globules into small micelles, which are easily digested, absorbed and assimilate into the system, resulting in availability of extra metabolizable energy to the birds.Due to wide HLB ,Better micelle formation and Stable emulsion there is value addition in digestion of oil / fat.Lipized DS has exhibited better weight gains and energy sparing effects, highlighting the potential for a partial oil or fat replacement.