Nitrogen Components in the Digesta of Sheep Fed Corn Gluten Meal and Urea

Abstract

Sixty-five lambs were used in a growth, blood composition and digestive tract contents nitrogen fractionation study. Fifty lambs were used to compare five rations in which supplemental nitrogen was furnished by either CGM or urea. The rations contained either 0, 10, 20, 30, of 40% of the total nitrogen from urea with the remaining portion of the supplementary nitrogen being supplied by CGM. A faster rate of gain was obtained from the rations in which 100 or 75% of the supplemental nitrogen was furnished by CGM, lending support to the idea that some preformed supplementary dietary protein is desirable for growth. Plasma amino acid levels varied considerably among treatments with trends toward lower levels of total essential amino acids in lambs fed the higher levels of dietary urea. High levels of dietary CGM tended to give increased plasma leucine while high levels of dietary urea resulted in increased plasma lysine. Fifteen lambs were fed the same five rations and sacrified after a 21-day feeding period. Digesta samples were taken from the reticulo-rumen, omasum, abomasum, duodenum, jejunum, ileum, cecum and colom. As the percentage of urea in the diet increased there was a decrease in the percentage of dietary nitrogen recovered in the rumen. Most endogenous nitrogen secretion occurred in the duodenum. Protein nitrogen decreased from the omasum to the jejunum and was accompanied by an increase in amino nitrogen in these same areas. Amino acid analyses, expressed as a molar percentage of the total, indicated that urea additions may change the percentage of certain essential amino acids in the abomasum.