Vitamin C deficiency in birds

Vitamin C deficiency in birds

Bhand Akshata Chandrakant¹, Ravi Mohan Shukla²

PhD Scholar, Division of Medicine, Indian Veterinary Research Institute, Izatanagar, Bareilly – 243122. Email ID – drakshatavmc@gmail.com

M.V.Sc Scholar, Department of Veterinary Pathology, Veterinary College and Research Institute, Orathanadu, TANUAVAS- 614625 Email ID– drshuklavpp@gmail.com

 Abstract

Vitamin C, primarily found in fruits and green plants, has diverse functions, including electron transfer reactions, metabolic oxidation of amino acids, and promoting iron absorption. Its deficiency can lead to scurvy, affecting wound healing, capillary fragility, and bone strength. Poultry, capable of synthesizing vitamin C, may require supplementation during stress conditions. Understanding the metabolic needs of vitamin C in various species, such as poultry, is crucial. While supplementation is generally unnecessary for healthy animals, stress conditions increase requirements. Vitamin C, existing in two forms as L-ascorbic acid and dehydro-L-ascorbic acid, is a crucial biological compound susceptible to destruction through oxidation, accelerated by heat and light. The vitamin’s metabolism involves absorption through a sodium-dependent transport system, equilibration with the body pool, and excretion in urine. Ascorbic acid is widely distributed in tissues, with highest concentrations in specific organs. Its role extends to collagen synthesis, hormone production, and protection against free radicals. Fortification considerations, safety aspects, and studies on supplementation effects highlight the importance of managing vitamin C levels in animal diets. Overall, maintaining optimal vitamin C levels is essential for ensuring the well-being and performance of animals, particularly during stressful situations.

Keywords: Vitamin C, Birds, scurvy, Metabolism, Absorption, etc.

Introduction

• Vitamin C occurs in two forms, namely L-ascorbic acid (reduced form) and dehydro-L-ascorbic acid (oxidized form).
• Although in nature the vitamin is primarily present as ascorbic acid, both forms are biologically active.
• The L-isomer of ascorbic acid is biologically active; the D-isomer is not. In nature, the reduced form of ascorbic acid may reversibly oxidize to the dehydroxidized form, the dehydroascorbic acid is irreversibly oxidized to the inactive diketogulonic acid.
• Since this change takes place readily, vitamin C is very susceptible to destruction through oxidation, which is accelerated by heat and light.
• Reversible oxidation-reduction of ascorbic acid with dehydroascorbic acid is the most important chemical property of vitamin C and the basis for its known physiological activities and stabilities (Moser and Bendich, 1991).
• Vitamin C is the least stable and, therefore, most easily destroyed of all the vitamins.

Properties and metabolism

• Vitamin C is a white to yellow-tinged crystalline powder
• It crystallizes out of water as square or oblong crystals, slightly soluble in acetone and lower alcohols.
• The vitamin is more stable in an acid than an alkaline medium.
• A number of chemical substances, such as air pollutants, industrial toxins, heavy metals and tobacco smoke, as well as several pharmacologically active compounds, among them some antidepressants and diuretics, are antagonistic to vitamin C and can lead to increased requirements for the vitamin.
• The metabolic need for ascorbic acid is a general one among species, but a dietary need is limited to humans, subhuman primates, guinea pigs, fruit-eating bats, some birds (including the red-vented bulbul and related Passeriformes species), insects, and perhaps certain reptiles (McDowell, 2000).
• Under normal conditions, poultry can synthesize vitamin C within their body. Vitamin C is absorbed in a manner similar to carbohydrates (monosaccharides).
• Intestinal absorption in vitamin C-dependent animals appears to require a sodium-dependent active transport system (Johnston, 2006). Ascorbic acid is readily absorbed when quantities ingested are small, but limited intestinal absorption occurs when excess amounts of ascorbic acid are ingested.
• Bioavailability of vitamin C in feeds is limited, but apparently 80% to 90% appears to be absorbed (Kallner et al., 1977).
• Site of absorption in the guinea pig is in the duodenal and proximal small intestine, whereas the rat showed highest absorption in the ileum
• In its metabolism, ascorbic acid is first converted to dehydroascorbate by several enzymes or non enzymatic processes and can then be reduced back to ascorbic acid in cells (Johnston et al., 2007).
• Absorbed vitamin C readily equilibrates with the body pool of the vitamin. No specific binding proteins for ascorbic acid have been reported, and it is suggested that the vitamin is retained by binding to subcellular structures.
• Ascorbic acid is widely distributed throughout the tissues, both in animals capable of synthesizing vitamin C as well as in those dependent on an adequate dietary amount of the vitamin.
• In experimental animals, highest concentrations of vitamin C are found in the pituitary and adrenal glands, and high levels are also found in the liver, spleen, brain and pancreas. Vitamin C also tends to localize around healing wounds. Tissue levels are decreased by virtually all forms of stress, which also stimulates the biosynthesis of the vitamin in those animals capable of synthesis.
• Ascorbic acid is excreted mainly in urine, with small amounts in sweat and feces. In guinea pigs, rats, and rabbits, CO2 is the major excretory mechanism for vitamin C. Primates do not normally utilize the CO2 catabolic pathway, with the main loss occurring in the urine. Urinary excretion of vitamin C depends on body stores, intake and renal function.

Functions

Function of vitamin C is related to its reversible oxidation and reduction characteristics

• it plays an important role in reactions involving electron transfer in the cell
• Metabolic oxidation of certain amino acids, including tyrosine.
• Ascorbic acid has a role in metal ion metabolism due to its reducing and chelating properties. This results in enhanced absorption of minerals from the diet and their mobilization and distribution throughout the body.
• Ascorbic acid promotes non – heme iron absorption from food  and acts by reducing the ferric iron at the acid pH in the stomach and by forming complexes with iron ions that stay in solution at alkaline conditions in the duodenum.
• Carnitine is synthesized from lysine and methionine and is dependent on two hydroxylases, both containing ferrous iron and L-ascorbic acid. Vitamin C deficiency can reduce the formation of carnitine, which can result in accumulation of triglycerides in blood and the physical fatigue and lassitude associated with scurvy.
• Decreasing levels have caused nonspecific sperm agglutination. Its promotion of collagen synthesis, its role in hormone production, and its ability to protect cells from free radicals, may explain its reproductive actions.

Requirements

• Vitamin C dietary-dependent species, including poultry, lack the enzyme L-gulonolactone oxidase. Domestic animals such as poultry have the ability to biosynthesize ascorbic acid within their body.
• However, biosynthesis of vitamin C is limited in very young birds and increases with age up to about 60 days of age (Leeson and summers, 2001).
• It seems that broiler chicks with higher growth rates have a high demand for antioxidant defense and thus a higher vitamin C requirement (Surai et al., 2002).
• In general, research studies have shown that healthy animals under ordinary conditions do not respond to supplemental vitamin C and hence there is no recommended requirement established by the NRC. However, Marks (1975) proposed vitamin C requirements 50-60 mg / kg/diet for poultry
• Although vitamin C can be synthesized by poultry, the synthesis is reduced or the requirements for vitamin C are increased during times of stress. During times of environmental, nutritional or pathological stress, the addition of ascorbic acid to the birds’ feed or to their drinking water appears to alleviate many of the undesirable physical consequences of exposure (e.g., chronic adrenocortical activation, immunosuppression, weight loss and reduced egg production) to single or multiple concurrent stressful stimuli such as high environmental temperature, beak trimming, coccidiosis challenge and transportation

Sources

• The main sources of vitamin C are fruits and green plants, but some foods of animal origin contain more than traces of the vitamin.
• Vitamin C occurs in significant quantities in animal organs, such as liver and kidney, but in only small quantities in meat.
• Vitamin C is very low in the predominant feedstuffs for poultry (i.e., grains and plant protein supplements).
• Postharvest storage values vary with time, temperature, damage and enzyme content.

Deficiency

• Poultry are able to synthesize vitamin C and thus it is assumed they do not require dietary sources of the vitamin. However, for newly hatched poultry there is a slow rate of ascorbic acid synthesis and this combined with encountered stress increases probability of vitamin C deficiency.
• The chick is subject to considerable stress conditions, including rapid growth, exposure to hot or cold temperatures, starvation, vaccination and disease conditions such as coccidiosis.
• There are only a few wild birds that have a direct need for vitamin C. These include the red-vented bulbul (Pycnonotus cafer)and the willow ptarmigan/red grouse (Lagopus lagopus) as well as the crimson sun-conure, a form of parrot.
• Birds in general do not need vitamin C in their diets as it can be produced from glucose in the liver. If a bird is suffering from liver disease, therefore, it may require a dietary source of vitamin C.
• Vitamin C is needed for the formation of elastic fibres and connective tissues and is an excellent anti-oxidant similar to vitamin E.
• Deficiency leads to scurvy in which there is poor wound healing, increased bleeding due to capillary wall fragility and bone weakness.
• Vitamin C also increases gut absorption of some minerals, such as iron. This may be important for chronically anaemic patients, but can be a danger for softbills, such as the mynah and toucan families, as these birds are prone to liver damage from excessive dietary uptake of iron.

Fortification consideration:

• Supplementation of vitamin C would not normally be recommended for common livestock species (ruminants, poultry, swine and horses) under normal management and feeding regimes.
• As previously mentioned, stress conditions do affect vitamin C synthesis and supplementation considerations must take this into account. Kolb (1984) has summarized various types of stress that apparently have increased demands while reducing animals’ capability to synthesize vitamin C:
• Dietary conditions: deficiencies of energy, protein, vitamin E, selenium, iron and starvation, etc.
• production or performance stress: high production
• transportation, animal handling and new environmental location stress: animals placed in new surroundings and stressful management practices
• temperature: high ambient temperature or cold trauma;
• Disease and parasite: fever and infection reduce blood ascorbic acid, while parasites, particularly in the liver, disturb ascorbic acid synthesis and increase requirements for the vitamin.
• Various studies have demonstrated beneficial effects of low supplemental levels of 50 to 100 mg per kg (23 to 45 mg per lb) of ascorbic acid in diets of broilers or laying hens exposed to heat stress
• Supplementation with ascorbic acid at 1,000 ppm in drinking water for 24 hours prior to stimuli resulted in a significant reduction in the length and intensity of fear responses in broilers.

Vitamin Safety

• In general, high intakes of vitamin C are considered to be of low toxicity. A number of studies with chickens and turkeys have shown no effect when birds were fed high levels of ascorbic acid (NRC, 1987).
• Dietary supplementation of ascorbic acid even at levels as high as 3% had no appreciable effects on body weight gain, feed intake and feed efficiency of growing chicks (Nakaya et al., 1986).
• One sign is excess accumulation of iron in the liver

References:

Moser U, Bendich A, Machlin L. Handbook of vitamins. FAO: New York, NY, USA. 1991.

McDowell LR. Vitamins in animal and human nutrition. John Wiley & Sons; 2000 Oct 11.

Johnston CS, Corte C, Swan PD. Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults. Nutrition & metabolism. 2006 Dec;3(1):1-5.

Kallner A. Serum bile acids in man during vitamin C supplementation and restriction. Acta Medica Scandinavica. 1977 Jan 12;202(1‐6):283-7.

Johnston L, Laverty G. Vitamin C transport and SVCT1 transporter expression in chick renal proximal tubule cells in culture. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. 2007 Mar 1;146(3):327-34.

Leeson S. Vitamin requirements: is there basis for re-evaluating dietary specifications?. World’s Poultry Science Journal. 2007 Jun;63(2):255-66.

Surai PF. Natural antioxidants in avian nutrition and reproduction. Nottingham: Nottingham University Press; 2002.

Marks J, Marks J. Vitamin C: Ascorbic acid. A Guide to The Vitamins: Their role in health and disease. 1975:137-44.

Kolb B. Functions of the frontal cortex of the rat: a comparative review. Brain research reviews. 1984 Nov 1;8(1):65-98.

NAKAYA T, SUZUKI S, WATANABE K. Effects of High Dose Supplementation of Ascorbic Acid on Chicks. Japanese poultry science. 1986 Sep 25;23(5):276-83.

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