By: Dwayne Summach, MSc, PAg, Regional Livestock Specialist
Vitamins are used by beef cattle to efficiently utilize other nutrients. Many metabolic processes are started and controlled by specific vitamins throughout a cow’s life. The newborn calf is born with no vitamin stores and is fully dependent upon the vitamins that are contained in the dam’s colostrum. If the dam’s diet is deficient of vitamins, then the colostrum will be as well. The net result will be a calf with a poorly functioning immune system and reduced growth rate.
Cows that are eating green grass are able to obtain many of the vitamins they require from the rumen microbes. Beta-carotene is used as a precursor for vitamin A, alpha tocopherol is used to make vitamin E. These components are abundant in green, actively growing grass and cows are able to store any extra fat soluble vitamins for use at a later date. When the grass dries out and browns off early, as it did this year, the time to store up extra vitamins gets cut short and the period of withdrawal begins early.
Preventing vitamin deficiency is possible through dietary supplementation. The amount of vitamin A required by a dry cow is typically in the range of 45,000 International Units (IU) per day. When she is lactating, the requirement increases to approximately 65,000 IU per day. Commercially available mineral supplements will often contain an appropriate level of vitamin A. Vitamin E plays a role in the uptake and storage of vitamin A, the maintenance and function of muscles, and the vascular system. While the amount of vitamin E for a mature cow has been traditionally estimated at 200 IU per day, recent findings indicate that there is benefit to providing 400 IU per day to cows eating dry forages in northern latitudes.
Providing adequate vitamins is part of providing the balanced nutrition required to obtain optimum production levels. If you have any questions regarding vitamin levels or livestock nutrition, contact your Regional Livestock Specialist.