The Value of Vitamin A
According to Dr. Greg Hanzlicek, with the Kansas State Veterinary Diagnostic Laboratory (KSVDL), Kansas had an unusually high number of stillbirth cases and weak born calves in the spring of 2019. After many laboratory tests, it was concluded that the problem stimmed from a lack of energy, protein, Vitamin A, or combinations of all of these.
Research has shown that low vitamin A levels during pregnancy are associated with abortions, stillbirths, and weak born calves. In addition to playing an important role in reproductive efficiency, vitamin A is essential for vision, bone growth, and maintaining epithelial tissue such as skin and hooves.
Animals obtain vitamin A from consuming green forage and/or the addition of vitamin A supplements to the diet. Lush green pastures contain high amounts of vitamin A. As plants mature and during times of drought, the amount of vitamin A decreases. In general, animals obtain adequate amounts of vitamin A by grazing green forage. Animals grazing green pastures will build a healthy store of vitamin A in the liver. When vitamin A is in short supply, the stores in the liver prevent deficiencies. According to Dr. Lalman, Extension Beef Cattle Specialist Oklahoma State University, the stores should last 2 to 4 months during times of deficiency.
Preventing vitamin A deficiency depends on producers being attentive to the environmental conditions that favor low vitamin A levels in forage. During these times, producers need to supplement the diet with vitamin A. Producers need to be aware that Vitamin A supplements degrade rapidly, so vitamin A supplements should not be stored for long periods of time. In addition to vitamin A supplementation, research indicates that diets low in protein result in poor absorption of vitamin A. It is important that producers ensure that the rations have sufficient protein levels. Lastly, since colostrum contains high levels of vitamin A, producers need to ensure that newborns obtain adequate amounts of colostrum at birth.
Most of Oklahoma had below average rainfall for the year of 2022. This resulted in pasture quality decreasing earlier than normal. Due to this year’s lack of green forage, liver stores of vitamin A may be inadequate for the animal’s needs. Producers need to ensure that the diets of their cattle have adequate amounts of vitamin A, energy, and protein.
Dr. Dave Lalman, OSU Extension beef cattle specialist, answers questions from producers and offers advice about vitamin A deficiencies in livestock on SunUpTV at https://www.youtube.com/watch?v=NIbN1qT_3lY
