Dr. Partha P. Biswas
Former Associate Professor & HOD
Dept. of Zoology, Ramakrishna Mission V.C. College
Kolkata 700118,W B.
Senior Consultant ( Acting ), W. Bengal
Poultry, Aqua & Vet supplements & medicines
Hyderabad 500070, Telengana.
Phosphorus (P), the second most prevalent mineral in the body after calcium (Ca), is one of the macrominerals required in poultry diets for optimal growth, development, genomic function, good quality flesh, and eggs production. P is well recognised for its participation in several metabolic and structural processes. It is essential for obtaining maximal genetic potential in growth, feed efficiency as well as skeletal development. Because P plays such an important part in growth, bone formation, and mineralization & it’s need is greatest while animals are developing. In addition to its involvement in bone, P is important in glucose and fat metabolism, as well as in the regulation of the immune system. Diets of poultry birds, are routinely supplemented with mineral feed phosphates since the amount of bioavailable P generated by maize and other plant-based feed components is considered to be insufficient. Feed P is also generated from nature’s limited rock phosphate reserves. As a result, the animal’s use of plant P sources must be improved in order to lower the animal’s finite feed P use. Plant P sources contribute to the long-term viability of chicken meat and egg production. Two-thirds of the entire phosphate content in plant seeds is stored as phytate P and rest excreted. Chick has a limited ability to degrade phytate phosphorus by gut microbes. Increased excretion of phosphorus with additional nutrients in the manure leads to excessive residual phosphorus polluting soil & groundwater.
PHYTATE IS A PLANT PHOSPHATE
Phytic acid may strongly chelate multivalent metal ions, particularly the positively charged ions zinc, calcium, and iron. The chelates are known as phytates. Phytic acid, also known as hexaphosphorylated inositol (IP6 or InsP6), is a phosphate storage form that is frequently found in the vacuole of plant seeds following production. Phytate, often known as phytic acid, is a naturally occurring chemical compound found in plants. As a reactive anion, it produces a wide range of insoluble salts with divalent and trivalent cations. Phytate also creates a compound with the protein, reducing its availability. Protein-phytate complexes are produced in the gut of chicks. The production of protein-phytate complexes begins in the seed during ripening, when phytate accumulates largely in the aleuronic layer of monocotyledonous seeds and in the protein bodies of dicotyledonous seeds. Excess Ca in the diet causes the production of calcium phytate complexes, which are very insoluble and poorly digested. Because zinc forms the most insoluble salt with phytic acid, it is a limiting mineral in high phytate diets because it forms a very insoluble complex at pH 6.4, which is the pH of the upper intestine where most mineral absorption occurs.
POULTRY BIRDS FEEDING INGREDIENTS & PHYTATE
Cereal grains, oil seed meal, and grain by-products are the most frequent feed components used in commercial chicken feed. The majority of the total P found in these foods (60-80%) is in the form of phytic acid. The phytic acid concentration of various varieties of bran can vary greatly. Rice bran has around 10% phytic acid, while wheat bran and rye bran have just 5%. The oat bran contains about 6%.
PHYTATE P HAS LOW BIOAVAILABILITY.
Phytate phosphorus is physiologically less accessible to chicken birds due to a lack of endogenous phytase, which hydrolyzes phytic acid. The capacity of chicken to use phytate phosphorus is widely debated due to the various parameters impacting phytate hydrolysis, such as dietary calcium content, inorganic phosphorus, and vitamin D3, as well as the age and genotype of birds. According to the data, the level of endogenous phytase in young birds is extremely low, but it grows a bit with age.
PHYTIC ACID IN POULTRY DIET AS AN ANTINUTRITIVE FACTOR
Phytic acid is regarded as an antinutritional factor in chicken because it binds with phosphorus and other essential elements, reducing their availability. It is also known that phytic acid binds to proteins, limiting their availability. Recent study indicates that phytic acid suppresses the actions of pepsin, trypsin, and amylase.
APPLICATION OF MICROBIAL PHYTASE
Fungi, yeast, and bacteria are the most abundant phytase makers among microorganisms. Plant phytases are not as efficient as microbial phytase. Plant phytases perform poorly than microbial phytases due to a narrower pH range. Microbial phytases degrade phytate by 73-80%. Adding phytase from Aspergillus niger and phytase from Escherichia coli to the diet can aid in the release of P from phytate.The first enzyme used in industrial manufacture was fungal phytase. Microbial phytases degrade phytate by 73-80%. Lactobacillus is the most abundant phytase producer.The enzyme phytase degrades phytate into lesser phytate esters and inositol.Microbial phytase improves the digestibility and availability of phytate-bound phosphorus, calcium, zinc, and copper in cereal-based poultry diets. This phytase has also been shown to increase crude protein and amino acid digestibility in female broilers.
ENVIRONMENTAL IMPACT OF EXCESSIVE USE OF ELEMENTAL PHOSPHORUS
Phosphorus is one of several pollutants that are causing concern about the impact of poultry farming. This element is commonly included in commercial diets of broilers or laying hens in amounts that exceed the animals’ actual needs, and as a result, a large amount of phosphorus ends up in the excreta. Feed supplementation with Pi must be done with caution because it accounts for around 50-75% of the total cost of the mineral mix, and excess phosphate discharged into the environment via faeces can promote eutrophication in freshwater bodies. Apart from no environmental problems, studies have shown that microbial phytase supplements lower cholesterol levels in egg yolk in poultry birds.
Fig1: Phytate complex and the mode of action of phytase.