J. Anim Sci.
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J. Anim Sci. 1970. 30:1012-1018.
© 1970 American Society of Animal Science
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Estimation of Critical Plasma and Liver Vitamin a Levels in Feedlot Cattle with Observations upon Influences of Body Stores and Daily Dietary Requirements1

R. H. Kohlmeier2 and Wise Burroughs3

Iowa Agriculture and Home Economics Experiment Station,,4 Ames

Abstract

Thirty-two pens of yearling beef cattle were pen fed eight levels of vitamin A in a highcorn finishing ration to determine minimum plasma and liver vitamin A levels compatible with maximum or near maximum live weight gains. These plasma and liver values were supplemented with similar values obtained at nine 28-day intervals on eight steers individually fed similar rations for purposes of determining time-rate changes during depletion and repletion of vitamin A body stores. The results indicated that no dietary vitamin A was required for good feedlot performance so long as plasma and liver vitamin A remained above 25 µg/ 100 ml and 2 µg/g, respectively. The results further indicated that cattle entering the feedlot with medium liver vitamin A (20 to 40 µg/g) will have sufficient tissue reserves for 90 to 120 days under normal feeding conditions. However, cattle with low liver vitamin A reserves (less than 5 µg/g) would require vitamin A almost immediately upon entering the feedlot.

Footnotes

1 Journal Paper No. J-6219 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 869.

2 Department of Veterinary Physiology and Pharmacology.

3 Department of Animal Science.

4 Appreciation is expressed to Distillation Products, Inc., Rochester, New York, for supplying vitamin A.






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Copyright © 1970 by the American Society of Animal Science.