Physiological importance of vitamin C in ruminants | ?????????? ?????? ? ???????? ??? ?????????

In the somatic cells of mammals and birds, ascorbic acid (vitamin C) is synthetized from L gulonic acid and therefore does not fit in the generally accepted vitamin definition. Exceptions are primates and Guinea pig that have to take this substance by per oral route. Therefore, ascorbic acid is considered as not significant in ruminant supplementation and for a long time it was thought that its only practical usage is in calves that are younger than 3 weeks because they don't synthetize it in sufficient amounts. It takes part in hydroxylation of lysine and proline during collagen synthesis and induction of tissue reparations. In the brain, C vitamin inhibits activity of dopamine - dependent adenyl cyclase thus indirectly influencing transmission of the nerve signals. It is also involved in cholesterol transformation to bill salts and by acting in the cytochrome P-450 metabolism in the liver, it is involved in detoxification of some medicaments and pollutants. Vitamin C prevents formation of atherosclerotic deposits in the blood vessels. Also, it has a role in the anti-oxidative defense and acts as anti-inflammatory agent. It is believed that during stress, it can ameliorate harmful histamine effects and it also plays a significant role in the cortisol and ACTH metabolism. There are scientists pointing connection between facts that humans can't synthetize vitamin C with higher frequency of malignancies. Another proof of the vitamin C complex role is its influence on the sexual hormones synthesis and reproduction. There are numerous data in the recent literature proving that parenteral vitamin C application leads to the improved neutrophil functions in different species. It is well known, that for fulfilling basic functions such as migration, adherence and phagocytosis neutrophils need more ascorbic acid. In this way, a role of ascorbic acid in the defense against microbial agents and in ameliorating negative stress effects is indubitably confirmed, even in species that are able to synthetize it.