THE IMPORTANCE OF VITAMINS IN THE POULTRY SECTOR
THE IMPORTANCE OF VITAMINS IN THE POULTRY SECTOR
Vitamins are a heterogeneous group of organic molecules required in small amounts by animals but essential for maintaining normal body functions, growth, and reproduction.
A deficiency of one or more vitamins can lead to a range of deficiency symptoms or syndromes that can severely compromise production, while an adequate intake of vitamins is key to maintaining animal functions in balance, especially during and after periods of illness or stress, to support recovery of defenses and productivity.
FAT-SOLUBLE AND WATER-SOLUBLE VITAMINS
Chemically, vitamins are divided into two categories: fat-soluble (Vitamins A, D, E, and K) and water-soluble (Vitamin C and B-complex vitamins).
Fat-soluble vitamins are absorbed at the intestinal level in association with fats; therefore, the percentage of lipids included in the feed also promotes their absorption.
Fat-soluble vitamins can be stored in the body’s adipose tissues, whereas water-soluble vitamins, except for B3 and B12, are not significantly stored in tissues, making continuous dietary intake necessary, especially during periods of increased demand.
FAT-SOLUBLE VITAMINS
VITAMIN A
Vitamin A is necessary for normal growth, reproduction, and maintenance of frequently regenerating epithelia such as those lining the digestive tract, respiratory tract, and genital tract.
Vitamin A and its derivatives, retinoids, profoundly influence organ development, cellular proliferation, and differentiation.
Vitamin A acts like a hormone and is involved in regulating night vision.
Chicks hatched from eggs with low vitamin A content may show stunted growth, ataxia, anorexia, and immunodeficiency from the first days of life.
In adults, keratinization of the epithelium lining the upper digestive tract (oral mucosa to esophagus) occurs, along with impaired turnover of the intestinal epithelium, predisposing to enteritis.
In the eye, keratinization of the conjunctiva can progress to blindness.
VITAMIN D
Vitamin D refers to a group of compounds including ergocalciferol (vitamin D2), cholecalciferol (vitamin D3), and their metabolites.
Vitamin D3 is necessary for the proper absorption and utilization of calcium and phosphorus, essential for bone mineralization and eggshell formation.
Cholecalciferol, either synthesized endogenously from cholesterol or obtained from the diet, undergoes two hydroxylations: first in the liver to form 25-hydroxycholecalciferol, then in the kidney to form 1,25-dihydroxycholecalciferol, the most active form of vitamin D (500–1000 times more active than its precursor).
Vitamin D deficiency syndrome is similar to calcium deficiency: reduced mobility, signs of pain while walking, joint swelling, and deformities of the sternum, legs, and beak in growing birds. Laying hens produce smaller eggs with thin or absent shells.
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VITAMIN E
Vitamin E refers to a group of molecules with strong antioxidant properties. The biologically most active molecule and the one most commonly used as a feed additive is D-α-tocopherol.
Metabolically, vitamin E does not undergo significant modification but is incorporated into cell membrane phospholipids, where it performs its antioxidant function.
This function is supported by enzymes requiring trace elements such as copper, manganese, zinc, iron, and selenium; deficiencies in these elements increase vitamin E requirements.
Considerable evidence suggests there may be undiscovered metabolic roles for vitamin E, related to selenium and possibly other compounds.
During immune responses, for example, the production of inflammatory mediators like prostaglandin E2 can be influenced by available vitamin E levels, as well as phagocyte activity. Therefore, vitamin E also has an immunomodulatory role. Deficiency leads to symptoms resulting from oxidative damage to cell membranes, commonly: encephalomalacia (with torticollis and ataxia), exudative diathesis in young birds, and muscular dystrophy mainly in adults.
VITAMINA K
A group of molecules with anti-hemorrhagic activity.
The simplest form of this group is menadione, synthetic vitamin K3.
Vitamin K is essential for prothrombin synthesis, playing a key role in blood coagulation.
Vitamin K requirements increase during certain pathologies, especially hemorrhagic diseases such as coccidiosis or parasitic infestations.
Vitamin K deficiency symptoms are related to poor blood clotting: petechiae on skin and appendages exposed to trauma (legs and wings), chest petechiae, and increased blood spots in eggs.
Vitamin K has a high safety margin; no side effects are reported even at doses 1000 times higher than the requirement.
WATER-SOLUBLE VITAMINS
VITAMIN C
Domestic poultry do not have a strict dietary requirement for vitamin C as they can synthesize it from glucose.
Vitamin C has an important antioxidant role: it participates in numerous reactions and works synergistically with vitamin E, regenerating its reducing power. Vitamin C is stored in the adrenal glands and released during stress, when free radical production increases. During heat stress or disease, dietary supplementation may be necessary.
B-COMPLEX VITAMINS
B-vitamin supplementation is generally used to compensate for variable levels naturally present in feed and to ensure adequate intake due to their essential metabolic roles. B vitamins are involved at various levels in the main animal metabolic pathways, including energy metabolism.
| VITAMIN B1 – THIAMINE |
| Thiamine diphosphate is a key cofactor for enzymes involved in lipid, carbohydrate, and amino acid metabolism. In deficiency, muscle tissue catabolism can meet the requirement for weeks in adults, so deficiencies are rare. Symptoms are mainly related to nervous system impairment due to altered energy metabolism: anorexia, weight loss, drooping wings, muscle paralysis, convulsions, and opisthotonus (“star-gazer” posture). |
| VITAMIN B2 – RIBOFLAVIN |
| Riboflavin (B2) is part of redox enzyme systems and is vital for all metabolisms. High-protein and high-fat diets, like poultry diets, require elevated riboflavin. Deficiency causes poor feed conversion, reduced growth, occasional diarrhea, and perosis (leg deformities). Laying hens show reduced egg production and paler albumen because riboflavin is transferred to yolk and binds to albumen proteins, giving the weak yellow color. |
| VITAMIN B3 – NIACIN |
| Niacin is also part of redox enzyme systems. Deficiency manifests as anorexia, slow growth, oral inflammation, dermatitis, and perosis. Endogenous synthesis from tryptophan makes deficiencies uncommon. |
| VITAMIN B6 – PYRIDOXINE |
| Pyridoxine is an essential cofactor for enzymes in amino acid metabolism and regulates some lipid metabolism enzymes. Low-protein or imbalanced amino acid diets require higher B6. Deficiency causes anorexia, anemia, perosis, tremors, and spasmodic convulsions. |
| VITAMIN B5 – PANTOTHENIC ACID |
| Pantothenic acid forms coenzyme A, a cofactor in carbohydrate, lipid, and amino acid metabolism. Deficiency causes slow growth, weakness, and ruffled feathers. |
| VITAMIN B9 – FOLATE |
| Folates are enzymatic cofactors in carbon unit transfer reactions, including nucleic acid synthesis and amino acid interconversion. Deficiency impairs DNA synthesis and affects high-turnover tissues. Symptoms: anemia, leukopenia, weakness, lethargy, dermatitis, ruffled feathers. |
| VITAMIN B12 – CYANOCOBALAMIN |
| Cyanocobalamin (B12) is a cofactor in nucleic acid synthesis and carbohydrate, lipid, and amino acid metabolism. Deficiency causes growth retardation, gizzard erosions, and fatty liver. Note: B12, like folates and choline, donates carbon units, influencing reciprocal requirements. |
Since 1984, Tecnozoo has developed a line of multivitamin products to supplement diets, preventing deficiencies or covering periods of increased requirements, such as stress, pre-laying preparation, and production periods.
