The relationship between concentrations of plasma and hepatic vitamin A in steers intensively finished on high-grain rations low in carotene

Abstract

Data on plasma and liver vitamin A concentrations were obtained from 84 Hereford steers approximately two years of age and approximately 900 lb in body-weight. The animals were sampled from two experiments : 57 received high-grain rations low in carotene for 150 � 15 days, 27 received similar rations for 154 � 6 days. Plasma vitamin A levels in 18 animals were below 20 �g/100 ml, and these values were associated with hepatic levels of less than 10 �g/g. The regression of plasma vitamin A on the logarithm of liver vitamin A was significant (P<0.01) and the regression coefficients were not significantly different between experiments. The equation was y = -30.506 + 19.705 log x. This equation has only limited value for prediction over the whole range tested due to the large standard error (9.24) and the limited magnitude of the correlation coefficient (0.80).