Performance and Carotene Conversion in Hereford Heifers Fed Different Levels of Nitrate

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Abstract
Performance and the carotene-vitamin A status were studied in Hereford calves and yearlings fed 0.0, 0.6, and 1.2% calcium nitrate in diets containing 20% or 40% concentrates. The animals were fed a low carotene ration for approximately 100 days prior to the study in order to reduce liver vitamin A stores. Daily gain and feed consumption were not significantly influenced by nitrate level in the diet. Animals fed diets containing 40% concentrate consumed more feed and gained at a faster rate than those fed 20% concentrate diets. The addition of calcium nitrate to the ration had no apparent effect on carotene or vitamin A values of either the liver or plasma. Over the 100-day feeding period, increases in liver vitamin A storage were 69, 84, and 71 I.U./gm. liver for animals fed 0.0, 0.6, and 1.2% calcium nitrate, respectively. Increases in liver vitamin A and carotene were greater for calves than for yearlings, while increases in plasma vitamin A and carotene were smaller. Methemoglobin showed no apparent treatment effects. Interactions of the different variables were non-significant on all blood, liver, and performance data.