By Rick Schmidt, Oliver County Extension Agent
Vitamin A is a crucial to animal health. It is important to the immune system of the cow and for the cow to provide quality colostrum to their new born calf.
Beta-carotene is a precursor to Vitamin A, which is plentiful in green forages, so cattle on green pastures are seldom short of Vitamin A during the grazing period. As winter prolongs and the quality of forage that is in the hay yards following a drought may be in question.
Herds short of Vitamin A throughout the winter feeding period may struggle with calf health do to low quality antibodies in the cows first milk, which leads to lower quality immunities to fight off many health is- sues that young calves face.
Vitamin A deficiencies are sometimes hard to diagnose, but some common symptoms may include un-thriftiness or rough hair coat, but nothing that we can say, the calf in Vita- min A deficient just by its symptoms.
Vitamin A deficiency usually doesn’t lead to abortions, it is more in the calf health where problems arise. Cows can be very short of Vitamin A for long periods of time then the first signs of problems show up as a calf with chronic diarrhea from a weak immunity.
Cows that consume green forage for 4 months can store these Vitamins in their liver for long periods of time, however, it does run out after feeding poor quality, deficient diets in the winter.
Concerns are with calf health, but longer term affects such as rebreeding are also a concern. Late gestation is the most important time to make sure the Vitamin A requirements are met. Depending on the stored level of Vitamin A in the cows system will determine the needed amount needed to build up the cows antibodies in her colostrum. If depleted as a result of poor forages, it may be recommended to supplement at 100,000 IU per day if green forage is unavailable.
Older cows are more likely to have more Vita- min A stored in relation
to heifers and young cows. Young cows don’t have as much quantity and quality of colostrum as older cows which may lead to the calves to first become sick due to poor immune response come from first calf heifers.
Some producers will give injections of Multi Complex minerals or Vitamin ADE, which may solve some levels of deficiency. If this is the practice that works best for your operation, remember that these shots should be done well in advance of calving.
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