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1 Department of Animal Sciences, University of Nebraska-Lincoln, Lincoln 68583-0908
Five trials involving 168 Holstein cows and 20 heifers were conducted to determine the effect of vitamin A supplementation at high concentrations, 1 or 2 million IU, compared with 100,000 IU/d, on peripheral concentrations of progesterone and on several measures of reproductive performance. Supplemental vitamin A at high concentrations had no effect on circulating concentrations of progesterone in either cyclic or pregnant cows or on most measures of reproductive performance examined in trials. Thus, it was concluded that providing vitamin A at these high concentrations is not warranted.
Key Words: vitamin A progesterone reproduction dairy cows
Submitted on October 16, 1991
Accepted on May 4, 1992
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