Vitamins are described as "organic nutrients required in small quantities for a variety of biochemical functions." The majority of vitamins need to be supplied in the diet because they can not be synthesized in the body. There are water-soluble vitamins (WSV) and fat-soluble vitamins (FSV). The toxicity of water-soluble vitamins is unlikely as the animal will filter these out in the urine. However, the filtration of these vitamins makes the storage quantities very minimal, making it a requirement to provide WSV regularly in the diet. WSV are responsible for energy metabolism. Thiamin, Riboflavin, Biotic, Folic Acid, Vitamin B12, and Vitamin C are some of the better-known WSVs. All WSV have been classified as B vitamins, except for vitamin C. Ruminant bacteria can synthesize B vitamins to meet their requirements. Monograstrics, unlike ruminants, only have microbial digestion in the ceca and hindgut, therefore supplementation of these WSV is required.
I would like to touch on the basics of a couple of the WSVs. Vitamin B12 is the only WSV that has sufficient storage in the body. In ruminants, bacteria synthesize B12 as long as cobalt is present and is then stored in the liver. This vitamin is responsible for red blood cell health, therefore, the deficiency will cause large immature blood cells. Resulting in severe stunting, anemia, and head pressing. Folic acid works closely with B12, to make red blood cells and is required for DNA synthesis. Plant sources, including forage, provide abundant amounts of this vitamin. Deficiency symptoms include large immature red blood cells, spina bifida, and anemia. Thiamine is a very important B vitamin in our area due to the high sulphates in the water. Sulphates will tie up the thiamine and cause polio. The symptoms of this are neurological, including loss of balance, disorientation, wandering, blindness, and retraction of the head. It is important to understand your water and feed quality to prevent deficiencies of these WSV.
Vitamin C is the only water-soluble vitamin that is not classified as a B vitamin. The function of this vitamin includes being an antioxidant to promote wound healing and helps to synthesize several hormones. Growth and repair of connective tissue, teeth, bone, and cartilage also rely on vitamin C in the body. Fruits and vegetables provide vitamin C for humans, however, for ruminants synthesis of this vitamin occurs in the liver.
FSV are involved in animal structure, including bone synthesis and calcium absorption in the gut. Vitamin A, D, E, and K are the FSVs. Unlike WSV, these FSV have stores in the liver and adipose tissue. However, for bred cattle, the vitamin requirement for fetal development is much higher than these stores can provide. Therefore, extra supplementation is required during gestation.
Vitamin D is an estrogen-like hormone involved in the regulation of calcium/phosphorus metabolism (not a true vitamin). It stimulates the synthesis of collagen and other bone matrix proteins as well as bone resorption by osteoclasts and osteoclast recruitment. Bone resorption refers to the process where bone is broken down to release calcium into the bloodstream. Plant and animal tissue is the main source of vitamin D precursors, sunlight (UVB rays) then convert the precursors into vitamin D. This fat-soluble vitamin can be stored in the body, therefore toxicity can happen and will override progesterone and cause abortions, and decalcify bone. Deficiency of this vitamin causes bone abnormalities such as rickets and osteoporosis.
Vitamin A is essential for vision, reproduction, growth and maintenance of differentiated epithelia, and mucus secretions. The vegetative parts of plants provide this vitamin for animals. However, stored forage such as silage and hay will have oxidation occur and therefore, the concentration will be lower for mature or stored forage. It is important to get feed tests done to ensure the requirements are being met. Specifically for cows close to calving as vitamin A contributes to colostrum quality and calf vigour at birth. Deficiencies will cause abortions, low conception rate and libido, decreased immunity, blindness, and reduced feed intake and growth. However, it is important to prevent toxicity as well. Toxicity occurs when the concentration of vitamin A in the body becomes 10x the requirement of that animal. Symptoms of this toxicity include skeletal deformation and fractures, skin peeling, convulsions, and death.
Vitamin K plays a vital role in blood coagulation and bone metabolism. It is a complicated cycle so I won't go into detail but let me know if you'd like to know more. Vitamin K can be synthesized in ruminants or come from plants and bacteria. However, it is important to understand that feed additives can reduce the synthesis of vitamin K and therefore, supplementation may be required. The reason these additives alter the vitamin K synthesis is that feed additives change the microbial load in the rumen to adjust feed efficiency. Newborn animals do not have stores for vit K, therefore supplementation at birth is necessary. If these animals are deficient, they will have reduced bone density and can develop hemorrhagic disease.
Vitamin E, like vitamin C, is an antioxidant which helps protect cell membranes from damage by radicals. Radicals are highly charged and responsive molecules that can survive in the body independently but will bind with other molecules to alter cycles in the body. Vitamin E deficiency leads to fragile red blood cells and reduced fertility. This can result in white muscle disease in calves and lambs. Stiffness of the hindquarters or inability to rise is also a symptom of vitamin E deficiency.
Well, this was a long post with lots of information. This was meant to give ranchers a better understanding of what each specific vitamin does in the bodies of their animals. Deficiency and toxicity risks will vary depending on your location, soil, and water. Feed and water tests will help you understand what you are providing to the animals and inform you when supplementation is needed and at what rate. Consult a nutritionist to ensure the correct supplementation is being supplied year-round.