Glycosyl ureides in ruminant nutrition

Abstract

1. The fate of glucosyl urea (GU), lactosyl urea (LU) and corresponding mixtures of the free sugars and urea and their degradation products were examined during in vitro incubation of the compounds with rumen contents taken from donor sheep and steers at various stages of adaptation to these compounds.2. The sugar-urea bond was virtually unattacked in rumen contents from unadapted sheep and steers but generally a slow release of the galactose moiety occurred. After feeding LU or GU to animals for a period of approximately 10 d, the rates ofdisappearance of both bound urea and sugar had increased, but were still markedly slower than those of the corresponding free sugars and urea. In vitro rates of degradation of both free lactose and urea also increased in response to the feeding of lactose and urea to rumen content donor animals.3. Ammonia accumulation in rument contents when GU or LU were the substrates was notably lower than when equivalent amounts of glucose and urea or lactost: and urea were the substrates. 4.Bacterial growth was estimated using an vitro method based on incorporation of 32P into bacterial nucleic acids. Markedly different patterns of bacterial growth were observed depending on whether LU or lactose and urea were the substrates.

Evaluation of oro-coecal transit time: a comparison of the lactose-[13C, 15N]ureide 13CO2- and the lactulose H2-breath test in humans

“…Since the discovery of the formula by Schoorl (1903) at the beginning of this century, the chemical properties and physiological behaviour of GU have been intensively studied (Benn and Jones, 1960;Goodman, 1958;Helfrich and Kosche, 1926;Hofmann, 1931;Hynd, 1926;Mayer, 1909) especially in ruminant nutrition (Merry, Smith and McAllan, 1982). Glycosyl ureides were found to be degraded in the rumen more slowly than the single components, and to have the advantage of supplying both the ammonia and the energy needed for microbial protein synthesis simultaneously (Merry, Smith and McAllan, 1982).…”

“…Glycosyl ureides were found to be degraded in the rumen more slowly than the single components, and to have the advantage of supplying both the ammonia and the energy needed for microbial protein synthesis simultaneously (Merry, Smith and McAllan, 1982). The molecular bond between the carbohydrate moities and the urea has been shown to resist enzymatic degradation in the gastrointestinal tract, but to be split by selected intestinal microbes in animals (Hofmann, 1931;Hynd, 1926;Merry, Smith and McAllan, 1982).…”

Validation of lactose[15N,15N]ureide as a tool to study colonic nitrogen metabolism

“…On oral administration, lactose-ureide reaches the colon unmodified, because the molecular bond between the carbohydrate moiety and urea in lactose ureide has been shown to resist enzymatic degradation in the human gastrointestinal tract (13 (28). The labeled NH 3 is mixed with the ammonia present in the colon, and as a consequence, the variations observed in the 15 Nlabeled measurement reflect the fate of total colonic NH 3 .…”