Nitrogen in the Abomasum of Wethers Fed Different Protein Sources

Abstract

The nature and quantity of nitrogen compounds reaching the abomasum of wethers fed soybean protein, zein, casein or gelatin were estimated using an indicator technique. The recovery of total nitrogen in the abomasum was highest with zein, intermediate with soy-bean and lowest with casein and gelatin. More nitrogen was recovered from the abomasum in the form of protein and less as purine-pyrimidine nitrogen when zein was fed than with either of the other protein sources. The amino acid patterns in abomasal contents were similar with soybean, casein and gelatin. Wethers fed zein had less threonine, lysine, arginine, aspartic acid and glycine and more leucine, phenylalanine, glutamic acid and proline in abomasal contents. Plasma urea levels were elevated with casein and gelatin and showed little increase after feeding zein or soybean protein. Plasma lysine was lower and phenyl-alanine and leucine were higher with zein than with the other proteins.