Studies on the Utilization of Urea by Growing Swine

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Abstract
Results of 3 experiments indicate that urea has no place in practical swine rations. Low levels of urea of 0.16 and 0.31% of the ration exerted no harmful effect on gains; slightly improved gains were obtained at these levels, however, feed required per pound of gain increased linearly as urea increased from 0.0 to 1.25% of the diet. Also per cent N retained decreased as the levels of urea in the diet were increased. Addition of 0.65% urea or, 0.04% methionine and 0.26% lysine or a combination of the urea and amino acids failed to significantly improve an 8% protein corn-soybean oil meal type ration in respect to rate of gain or feed conversion. The replacement of 10 or 20% of the protein with equivalent amounts of urea nitrogen, in diets containing 8 or 10% total protein from a mixture of whole dried egg and dried skim milk, significantly decreased the rate of gain and increased the feed required per pound of gain. The decreased performance was more severe on the lower level of protein.