Relation of Forage Carotene to Plasma Carotene and Vitamin A of Range Cows

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Abstract
Results of a 3-year investigation of the relationship between forage carotene and plasma carotene and vitamin A in New Mexico range cows during winter and early spring are presented. A significant linear relationship was found to exist between plasma vitamin A and the logarithm of forage carotene intake. The regression of precipitation and average mean air temperature upon forage carotene was highly significant. Standard partial regression coefficients indicated that temperature contributed considerably more to the fluctuation in forage carotene than did precipitation during this period. No visual clinical symptoms of vitamin A deficiency were observed in the cows used in this experiment, nor did blood plasma carotene or vitamin A drop below normal levels except for short periods. Range forage samples from southern New Mexico contained carotene during most of the months sampled. Forage samples collected in northern New Mexico contained no carotene for considerable periods. Copyright © . .