Distinguishing 25-Hydroxyvitamin D₃ from Vitamin D₃

25-Hydroxyvitamin D₃ is the direct form of vitamin D₃. Unlike vitamin D₃, which requires conversion in the liver via hydroxylation. This results in several key advantages: its absorption is significantly less affected by bile salts, chylomicrons, intestinal damage, or inflammation compared to vitamin D₃. It is also unaffected by impaired liver function, developmental issues, or variations in 25-hydroxylase enzyme activity. Critically, 25-Hydroxyvitamin D₃ demonstrates a bio-efficacy estimated to be 3-5 times greater than that of vitamin D₃.

Mechanisms of Action: How 25-Hydroxyvitamin D₃ Works

25-Hydroxyvitamin D₃ plays vital roles across multiple physiological systems:

• Bone Health: Elevates blood calcium levels, increases bone mineral density, stimulates bone cell proliferation and matrix formation, enhances calcium ion absorption and retention, and promotes skeletal mineralization.
• Reproductive Performance: Boosts progesterone synthesis, supports oocyte maturation, improves embryonic implantation rates, and aids embryonic development. It also regulates calcium-phosphorus metabolism and reproductive hormones (testosterone, estradiol) in testes and epididymides.
• Immune Function: Enhances macrophage chemotaxis and phagocytic activity, modulates lymphocyte activity to stimulate immunoglobulin production, and promotes the secretion of tight junction proteins to strengthen intestinal barrier integrity.
• Meat Quality: Facilitates myotube formation, supports postnatal muscle growth, increases the relative protein synthesis rate in livestock and poultry, and contributes to greater muscle mass.

Usage Considerations: Replacement and Combinations

While 25-Hydroxyvitamin D₃ can functionally replace vitamin D₃, a combined approach is often recommended for optimal cost-effectiveness. This is due to:

• The stabilized form of 25-Hydroxyvitamin D₃ is intended to be used as a feed additive in feed for all ruminants at maximum use level of 0.1 mg/kg complete feed, corresponding to 4,000 IU vitamin D ₃/kg feed.¹
• Strategic combination with vitamin D₃ offers a more cost-effective solution in many formulations.

Limitations of Increasing Vitamin D₃

Simply increasing the dosage of vitamin D₃ is not an effective strategy to enhance performance. Key limitations include:

• Absorption Constraints: Absorption efficiency is hindered by reliance on chylomicrons and is significantly impacted by intestinal health.
• Conversion Bottleneck: The liver's capacity to convert D₃ to the active 25-Hydroxy form is limited by liver health and 25-hydroxylase enzyme activity. Conversion efficiency decreases as dietary D₃ levels rise.

Calcium Absorption: The Essential Role of 25-Hydroxyvitamin D₃

The source or form of calcium supplementation is distinct from its absorption. Regardless of the calcium type (organic or inorganic), requires the absorption of calcium under the action of biologically active 25-hydroxyvitamin D₃ .

Application of 25 Hydroxyvitamin D₃ in Poultry

While crucial during the demanding late laying phase to prevent osteoporosis and fractures by replenishing calcium drawn from structural bone, 25-Hydroxyvitamin D₃ is equally vital early in a hen's life. Optimal structural bone development and medullary bone calcium reserves during the rearing and pre-lay period are fundamental for supporting sustained high production later.

Applicability Across Species

Current regulatory approval for 25-Hydroxyvitamin D₃ as a vitamin feed additive primarily covers swine and poultry. However, research findings indicate potential benefits in other species. Studies suggest it may improve body length in certain fish and enhance milk quality parameters in dairy cattle.

Benefits in Sows: Measurable Outcomes

Supplementation with 25-Hydroxyvitamin D₃ in sows yields significant, quantifiable benefits:

• Enhanced skeletal development and health in gilts, improving breeding readiness.
• Reduced farrowing duration and minimized loss of body condition and backfat.
• Increased number of live-born piglets, weaned piglets, and litter weaning weight.
• Improved bone strength and calcium/phosphorus content in offspring.

Available Formulations and Selection

25-Hydroxyvitamin D₃ is commercially available in concentrated forms (Leadsynbio specificizes 1.25%, 0.125%). The 1.25% concentration is typically suitable for premix and vitamin-mineral premix manufacturers, while the 0.05% concentration is often preferred by feed mills and integrated farming operations for direct inclusion into complete feeds.

Leadsynbio: Supplying High-Quality 25-Hydroxyvitamin D₃

Leadsynbio manufactures 25-Hydroxyvitamin D₃ raw material, offering key advantages:

• Innovative Production: Utilizes a unique, patented process simulating the natural hepatic metabolism of vitamin D₃ in vitro to yield high-purity raw material.
• Manufacturing Scale: Operates dedicated production facilities with hundred-ton capacity, ensuring consistent, reliable supply.
• Quality Assurance: Compliant with international standards including ISO 9001, ISO 14001, ISO 45001, and FAMI-QS. Normally the product contains more than the amount stated on the label.
• Technical Support: Provides application guidance and supports custom formulation development for specific customer needs.

¹Technical dossier/Supplementary information April 2023/2022-04-27 letter reply to EFSA Sin EFSA-Q-2021-00341.

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