Vitamin C plays multiple important roles in broiler chicken farming. Here are some common applications:

1. Anti-Stress: It helps reduce the adverse effects of stress on broiler chickens caused by high temperatures, high humidity, sudden interruptions in feed and water, vaccinations, diseases, molting, debeaking, handling, noise, and relocation.

2. Immune Enhancement: During stressful periods, chickens experience a decline in immune function. Supplementing with vitamin C can mitigate the impact of stress factors on their immunity. It protects lymphocytes, limits excessive secretion of adrenal steroids, reduces immune reactions, and provides some protection against infectious bursal disease.

3. Promotion of Bone Formation: Modern broiler chickens have rapid muscle growth but slower bone development, leading to issues like leg weakness. Vitamin C can enhance the binding capacity of duodenal calcium-binding proteins, helping to reduce economic losses caused by such problems.

4. Detoxification Assistance: Vitamin C is crucial for the activity of various enzymes in liver cells, enhancing the liver's ability to metabolize harmful substances. For instance, it helps hydroxylate cholesterol into metabolites important for bile acid formation. A deficiency in vitamin C can reduce bile acid secretion and impair liver detoxification capacity.

5. Improving Survival Rates and Growth Performance: Providing a daily dose of vitamin C to chicks can improve metabolism, strengthen their bodies, enhance appetite, promote growth and development, and increase survival rates.

In practical broiler chicken farming, the specific dosage and method of administering vitamin C may vary depending on several factors. Typically, broiler farms add 150-200 mg/kg of vitamin C to starter feed and 100-150 mg/kg to grower and finisher diets. Research has shown that adding 100 mg/L of vitamin C to the drinking water of 4-week-old chickens can significantly increase plasma vitamin C levels within 4 hours.

However, vitamin C is one of the most unstable vitamins, susceptible to degradation by high temperatures and heavy metal ions. Therefore, stable formulations of vitamin C are needed in the feed industry. When using vitamin C, it is essential to avoid combining it with substances like baking soda, aminophylline, iron ions, penicillins, cephalosporins, erythromycin, gentamicin, sulfonamides, vitamin B12, vitamin B2, vitamin K3, and vitamin K1, as these combinations may reduce the effectiveness of the medications or cause other adverse reactions. However, vitamin C and vitamin E have a synergistic effect and can be used together to enhance overall efficacy.

In summary, although poultry can synthesize vitamin C on their own, supplementation may be necessary in certain situations, such as in intensive production systems where birds experience significant stress and deplete their vitamin C reserves. Adding vitamin C appropriately, based on factors like the broiler's growth stage, health condition, environmental conditions, and product instructions, can help maintain good health and productivity in broiler chickens. The pharmacological actions of vitamin C include the following:

1. Participation in Hydroxylation Reactions:

   • Promotion of Collagen Synthesis: Collagen is an essential component of connective tissue, bones, and blood vessels. Vitamin C participates in the hydroxylation of proline and lysine, promoting collagen synthesis and helping maintain the integrity of the extracellular matrix, as well as the normal function of blood vessels, muscles, and bones.
   • Participation in Cholesterol Conversion: Vitamin C is involved in the hydroxylation process that converts cholesterol into bile acids, helping to reduce cholesterol levels in the blood.

2. Antioxidant Action:

   • Free Radical Scavenging: Vitamin C is a potent antioxidant that can neutralize excess free radicals in the body, reducing oxidative stress and protecting cell membranes, proteins, and DNA from oxidative damage.
   • Regeneration of Other Antioxidants: For example, vitamin C can convert oxidized vitamin E back to its reduced form, restoring its antioxidant function.

3. Enhancing Immune Function:

   • Boosting Phagocytic Function of White Blood Cells: This helps increase the body's resistance to pathogens.
   • Promoting Antibody Formation: This contributes to the enhancement of the body's specific immune response.

4. Promotion of Iron Absorption and Utilization:

   • Vitamin C can reduce ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), which is easier to absorb, thereby aiding in the prevention and treatment of iron-deficiency anemia.

5. Detoxification:

   • Vitamin C can reduce the toxicity of certain heavy metals, such as lead, mercury, and cadmium.

6. Prevention and Treatment of Scurvy:

   • Prolonged vitamin C deficiency can lead to impaired collagen synthesis, resulting in increased capillary fragility and symptoms of scurvy, such as bleeding gums and skin hemorrhages. Supplementing with vitamin C can prevent and treat scurvy.