Vitamin C

There is little concern about the bioavailability of vitamin C (ascorbic acid), because food animals (unlike humans, apes, and guinea pigs) are capable of synthesizing this vitamin. Nonetheless, vitamin C is often included in vitamin premixes for use in purified animal diets because of its antioxidant and putative antistress properties. Stored diets or premixes can lose vitamin C activity. Coating ascorbate with ethylcellulose minimizes the loss. Gadient[14] noted that both pelleting and extruding can markedly reduce the bioactivity of supplemental ascorbate added to feeds or premixes. Losses due to oxidation are well known, as ascorbic acid (reduced form) can be reversibly oxidized to dehydroascorbic acid, which in turn can be further irreversibly oxidized to diketogulonic acid. Both reduced and oxidized forms of ascorbate retain scurvy-preventing ascorbate activity, but diketogulonic acid has no activity. Both ascorbate and dehydroascorbate are heat labile, particularly when heat is applied in the presence of trace minerals such as Cu, Fe, or Zn.

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