Relationship between Plasma Vitamin A and Liver Vitamin A in Calves Fed a Vitamin A Depletion Ration and Calves Fed Minimum Levels of Vitamin A or Carotene

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Abstract
A linear relationship between the logarithm of plasma vit. A concentrations and the logarithm of liver vit. A concentrations was found for 15 Guernsey and 43 Holstein calves fed a vit. A depletion ration, and for 39 Holstein calves fed minimum levels of vit. A or carotene. The average age and weight of the depletion group was 128 [plus or minus] 19 days and 263 [plus or minus] 72 lb., and for the minimum levels group 200 [plus or minus] 9 days and 436 [plus or minus] 48 lb. The regression equations with their standard -errors of estimate were as follows: [image] = + 0.30 + 0.2964 X [plus or minus] 0.10 for the depletion group and [image] = + 0.50 + 0.2846 X [plus or minus] 0.11 for the minimum levels group, where X and Y are the logarithms of the liver and plasma vit. A concentration in [mu]g%, respectively. For a given concentration of liver vit. A, the depletion group had a lower plasma vit. A concentration than the group fed minimum levels of vit. A or carotene. For the prediction of liver concentration from plasma concentration, the regressions of logarithm of liver concentrations (X) on logarithm of plasma concentrations (Y) gave: [image] = - 0.02 + 2.3724 Y [plus or minus] 0.28 for the depletion group and [image] = - 0.77 + 2.5336 Y [plus or minus] 0.33 for the minimum levels group. These equations had applicable limits for prediction between approximately 4 and 26 [mu]g of vit. A/100 ml of blood plasma.