By Colby Elford, PAg, Livestock and Feed Extension Specialist, Moose Jaw
Vitamins are a very important part of beef cattle nutrition and are crucial for the animal to efficiently use other nutrients. Many metabolic processes are complex and are controlled by specific vitamins. Vitamins are classified as being either fat or water soluble. Vitamin A, D, E and K are fat soluble, while vitamin C and the complex of B vitamins are water soluble. Bacteria that live in the cow’s rumen are capable of synthesizing required amounts of B and K vitamins; however, vitamins A, D and E must be supplemented into their diet.
Vitamin A is stored in the animal’s liver and is essential for proper kidney function. It is also necessary in the development of healthy bones and teeth and reproductive and nervous tissue formation. Vitamin A also plays a vital role in immunity. Some signs of vitamin A deficiency are night blindness, lowered fertility, dead or weak calves, loss of appetite, rough hair coat, dull eyes and reduced feed intake.
Vitamin A is not found in plants; however, the precursor to vitamin A, carotene, is found in the pigments of green and yellow plants. Cows convert this molecule to vitamin A and it is either used or stored in the liver. It is not stored until the daily intake of carotene is five to ten times the normal requirement (or if vitamin A is supplemented at three to five times the normal requirement). Therefore, it is difficult for cattle to store this essential nutrient unless it is added to the diet.
Furthermore, both vitamin A and carotene in feed break down over time. Even if high quality forage is harvested with little weathering, experts say that after three months of storage there are very few vitamins or precursors remaining in that feed. So in most, if not all, feeding scenarios in Saskatchewan, vitamin A must be added to the diet to meet the cow’s requirements.
Vitamin D, sometimes called the sunshine vitamin, is formed by the action of sunlight on certain sterols. One of these sterols is found in the skin of cattle. Therefore, cattle that are exposed to sunlight have the ability to synthesize vitamin D. Some other forms of vitamin D are created in plants when they are cured by sunlight.
Vitamin D plays a large role in macro mineral function and absorption in cattle. Specifically, it helps regulate blood calcium and phosphorus levels by increasing the small intestine’s ability to absorb these minerals from the diet. Vitamin D works with calcium and phosphorous to prevent rickets in cattle and aids in the formation of sound bones and teeth. Deficiency signs include stiff gait, weakness, laboured breathing, swollen joints and bowed legs. A deficiency in pregnant cattle may result in dead, weak, or deformed calves.
Vitamin E is important for muscle function and disease resistance. Increased Vitamin E improves colostrum quality, immune function and reproductive performance. A deficiency in Vitamin E will result in retained placentas, reduced fertility and poor growth rates. Vitamin E is expensive but necessary. It is most important six weeks prior to calving, through to re-breeding. It is also necessary for calves at weaning time and during other stressful periods. There is a close relationship between Vitamin E and selenium but both must be present in the diet. Levels of vitamin E in forage vary greatly between crops.
If you have questions about their cattle’s vitamin intake, contact your nearest livestock and feed extension specialist or contact the Agriculture Knowledge Centre at 1-866-457-2377.