How Much Supplemental Vitamins do Cows Really Need?

摘要

Because of major production problems, vitamin A and to a lesser extent vitamin E are in very limited supply and prices have increased markedly. Because of price and scarcity, many nutritionists are re-evaluating vitamin supplementation strategies. Based on current information, the NRC (2001) requirements for vitamin A (approximately 75,000 IU/day for all cows) and vitamin E (500 IU/day for lactating cows and 1000 IU/day for dry cows) are adequate. However, feeding an additional 1000IU of vitamin E per day during the prefresh period (2 or 3 weeks prepartum) can improve cow health post partum. More data are needed but limited information suggest that for lactating cows, supplementation rates for vitamin D should be increased to about 1.5 X NRC (about30,000 IU/day). Because vitamin A is in very limited supply, supplementation may need to be prioritized. Because of low expected intakes of basal beta-carotene and the high requirement of vitamin A for colostrum synthesis, prefresh cows should be fed atNRC rates at the expense of other cows. Next highest priority is far-off dry cows, followed by lactating cows. Some supplemental vitamin A should be provided to all types of cows if possible; however, if necessary, the liver can supply adequate vitamin for several weeks, and perhaps up to a few months, without adversely affecting lactating cow health or productivity.