Vitamins are complex molecules found naturally or artificially in foods or as precursors to them. They are part of several metabolic processes and are required in minimal amounts for the proper functioning of the organism. In their absence, specific symptoms and deficiency diseases can be observed, corrected soon after the correct supplementation.
Vitamins A / D / E belong to the fat-soluble group, in which vitamin K is still found, thus forming the acronym ADEK. They have lipid-like absorption and are usually storable in the same locations as lipids. Unlike the water-soluble group, vitamins A / D, if supplemented in excess, have toxicity.
In practice, it is considered the most important vitamin to be supplemented for beef and dairy cattle. Some of the main functions of vitamin A are the Production of rhodopsin (vision pigment), maintenance of skeletal and epithelial tissue cells, spermatogenesis, and cell differentiation.
Vitamin A does not occur in plants, but vegetables are rich in precursors, carotenes. Some examples are B-carotenes, Alpha-carotenes, y-carotenes, and cryptoxanthin. These molecules are known as provitamin A because they are transformed into an active form in the animal organism.
B-carotenes are the most important provitamins A since almost every molecule absorbed is converted to retinal which is reduced to retinol. Some unconverted B-carotenes are absorbed intact and act as pigments for meat, eggs, milk, and fats.
Some problems due to disability:
- Eye injuries (night blindness);
- keratinization of the skin;
- Loss of mucous secretions with keratinization of the respiratory tract;
- Impaired spermatogenesis and abortions in females.
Animals confined to a diet based on corn and silage have higher vitamin A requirements per unit weight. Grazing animals may also be deficient as a result of forage quality. Newborn calves do not have a reserve, and the consumption of colostrum is important. If the cow’s diet has low vitamin values, colostrum will also have smaller amounts.
Vitamin D is the generic name that includes ergocalciferol (D2) and cholecalciferol (D3). D2 is synthesized from the steroid ergosterol, present in vegetables, fungi, and yeasts. D3, on the other hand, is considered the natural form present in animal tissues and can be formed under the skin by the action of solar radiation. Both forms have similar activities and can be supplemented.
The primary function of this vitamin is linked to the transport and absorption of calcium in the intestine, and failure in the mineralization of Ca and P can cause deficiencies such as rickets and osteomalacia.
Vitamin D deficiency reduces the ability to maintain calcium and phosphorus homeostasis, resulting in a decline in plasma phosphorus and, less often, a reduction in plasma calcium. This finally leads to the development of rickets in young animals and osteomalacia in adults; both are bone diseases, in which the main lesion is the inability to mineralize the organic matrix of the bone. In young animals, rickets causes enlarged and painful joints; the costochondral joints of the ribs are often easily palpable. In adults, lameness and pelvic fracture are common sequelae of vitamin D deficiency.
In the case of dairy farming, the biggest problem encountered with vitamin D deficiency is the so-called milk fever.
We have an article about vitamin E here on our blog, soon we will focus on the benefits and deficiency part of ruminants.
Vitamin E is linked to antioxidant activity, acting together with selenium in defense of vital phospholipids. Additional vitamin E supplementation in dairy cows during the peripartum period has shown positive results in the functions of macrophages and neutrophils, reducing the incidence of mastitis and reproductive problems.
Its supplementation in beef cattle increases the levels of alpha-tocopherol in the tissues, reducing the percentage of metmyoglobin in the muscle and the concentrations of free radicals in the meat.
Some problems due to disability:
- white muscle disease;
- muscular dystrophy;
- muscle degeneration.
Deficiency is linked to inadequate intake, dry pastures, poor quality food, accelerated growth rates, and overuse of unsaturated fats.
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