DIETARY ELECTROLYTE BALANCE in POULTRY (DEB)
Dr Srinivas Roa
Poultry consultant
Minerals vitally important for Poultry
It is well known that minerals form a vital part of all biological functions in all Poultry species. They are more important in Poultry nutrition than any other nutrient, being involved in thehot hens deb in poultry page expression and regulation of genes, in enzyme systems regulating cellular functions, osmotic balance, detoxification systems, and acid-base balance and structurally in bone metabolism.
To properly understand the importance of minerals it is necessary to take a trip back through time, to millions of years ago when life evolved from water to dry land.
For survival, a barrier (skin) evolved between the surrounding air and the fluid environment within cells. Systems had to develop to regulate the fluids within and surrounding the cells. Water was required to transport nutrients, gasses, waste products and hormones around the bodies.
Water also plays a critical role in lubricating and in balancing acids and alkali (bases) and other products of metabolism. It also has a great capacity to dissipate heat produced by reactions such as occur in digestion and during heat stress.
This is achieved electrically in conducting solutions that are produced when electrolytes are added to water. For instance, in the fluid between cells there are the key electrolytes, sodium bicarbonate (NaHCO3) and chloride (Cl) and within the cells potassium (K), phosphate (P), magnesium (Mg), some sodium (Na), calcium (Ca) and bicarbonate (HCO3) are found.
It is fascinating to find that the electrolytic activities of water are maximised at 37°C i.e., the approximate body temperature of poultry.
As they are present in very small quantities, the concentration of
electrolytes is expressed as milliequivalents (mEq). This is a measure of electrical charge and the potential to generate acids or bases. A major function of electrolytes is to assist in the maintenance of water balance within the body.
The regulation of water balance in the body is under control of hormones such as A.D.H. [Anti-Diuretic Hormone]. For instance, if the concentration of electrolytes in the blood plasma falls, A.D.H. release is suppressed and urine flows freely. The converse applies, as A.D.H. release increases the flow of urine will decrease.
Thirst is the driving force of water balance.
The key electrolytes Sodium (Na), Potassium (K), Chloride (Cl), Bicarbonate HCO3 have different essential functions.
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Cell function in Poultry explained
It is now possible to explain what is happening within the cells when Poultry are outside their Zone of Comfort. There is some tolerance and adaptation to temperatures as high as 25°C but above this, Heat Stress is evident.
Open mouth breathing and panting are designed to cool the deep body temperature by evaporating water from the surfaces of the lungs and respiratory tract. Water evaporation requires a considerable amount of heat energy, thus temperature is reduced. The body loses carbon dioxide [ CO2] and in the process bicarbonate [HCO3 ]. The progressive loss of CO2 gives
rise to the condition of alkalosis, which is a serious disturbance of acid-base balance.
Loss of electrolyte balance is perhaps the most serious outcome. All the body systems are affected when Dietary Electrolyte Balance (DEB) is lost. The major effect of this is the development of a complex alienation of the body chemistry following a rise in the deep body temperature. Normal heat regulating systems are soon overcome, hyperventilation (panting) occurs in an effort to cool the body by evaporating water from the lungs. In continuing hot and humid conditions this fails, there are severe changes in the blood, acid base balance (which is essential for normal functioning) is lost and so is the productivity of enzyme systems within cells.
Poultry stop eating and there are various behavioral responses such as squatting and wing spreading. Lost electrolyte balance results in the loss of potassium, sodium and bicarbonate in an increasing urine output.
In poultry nutrition, DEB is expressed as Na + K – Cl in mEq/kg or diet or in mEq/100 g of diet. Broiler and breeder diets usually have DEB indexes ranging from about 100 to 250 mEq/kg or 10.0 to 25.0 mEq/100 g. higher coefficient of absorption than divalent ions (Ca, Mg, P, S).
