J. Anim Sci.
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J. Anim Sci. 1971. 32:1233-1238.
© 1971 American Society of Animal Science
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Vitamin A Status of Steers as Influenced by Corn Silage Harvest Date and Supplemental Vitamin A1

F. H. Martin2, D. E. Ullrey, E. R. Miller, K. E. Kemp3, M. R. Geasler4 and H. E. Henderson

Michigan State University, East Lansing 48823

Abstract

One-hundred-eight steer calves, weighing an average of 244 kg, were randomly assigned to 12 lots of nine steers each. They were fed corn silage for 180 days which was harvested during September 13 to 16, October 17 to 20 or November 14 to 15. The silage was chopped into either fine (1 cm) or medium (2 cm) lengths. Within each lot, three animals were injected intramuscularly with 7 million IU of vitamin A at 147, 63 or 35 days antemortem. Three additional animals received these same treatments by intraruminal injection. The remaining three animals in each lot served as saline-injected controls. September-harvested silage provided more carotene than silage harvested in October or November, and fine chopping resulted in greater carotene destruction at all three harvest periods than medium chopping. Carotene intake from October and November silages appeared inadequate to sustain vitamin A reserves without supplemental vitamin A. Intramuscular injections of vitamin A were significantly more effective in supporting liver vitamin A stores than intraruminal injections. When vitamin A injections were made 35 to 63 days antemortem, liver vitamin A stores were higher than when injections were made 147 days antemortem, and the 147 day intraruminal injection produced no greater liver vitamin A stores than when no supplement was given.

Footnotes

1 Contribution of the Department of Animal Husbandry. Published with the approval of the Director of the Michigan Agricultural Experiment Station as Journal Article No. 5251.

2 Department of Nutrition, Harvard University School of Public Health, Boston.

3 Department of Statistics, Kansas State University, Manhattan.

4 Department of Animal Science, Iowa State University, Ames.






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Copyright © 1971 by the American Society of Animal Science.