Langfristige Fütterung von Azetylharnstoff an Milchkühe

Abstract

After an introductory survey of investigations dealing with the conversion of acetyl urea in the ruminant organism, a feeding trial using dairy cattle is described in which the effects of long-term acetyl urea feeding on the clinical picture and various performance parameters have been studied. Five Black-Pied cows of medium milk yield were fed a natural diet and received, over at least 14 months, a daily acetyl urea supplementation of 430 g (= 40 to 44% of the digestible crude protein). The clinical control, including the analysis of blood parameters, did not produce any deviation from normal. As to milk and butterfat yields, the experimental group reached results comparable to those of the control group. Over the entire experimental period the experimental group and the control averaged per cow and day of milking 11.1 and 11.3 kg FCM, respectively. The reproductive behaviour proved normal for all the cows under study. Postmortem findings of 4 cows revealed, among other things, chronic kidney alterations that cannot be safely exluded to be caused by the experiments. A stress over several months of two cows fed 850 g acetyl urea per day was not found to affect animal performance and health.

Post‐ruminal non‐protein nitrogen supplementation as a strategy to improve fibre digestion and N efficiency in the ruminant

“…These authors speculate that observed improvements in digestibility were due to N recycling back to the rumen. Attempts to manage the N release rate of dietary urea in the rumen with other forms of NPN (Bergner, Görsch, Wiesner, & Willer, 1977) suggests that N supply to the rumen may have been through rumeno-hepatic circulation, as proposed earlier (Egan & Moir, 1965). This body of work provides the first evidence that supplying the rumen with a source of N derived from endogenous circulation via post-ruminal NPN supplementation may be an efficient approach to facilitate fibre digestion and ruminal stability.…”

“…The first proposal to use amines as a method to encourage carbohydrate digestion in the ruminant was made more than a century ago (Zuntz, 1891) and later examined and verified as an effective NPN supplementation strategy (Hart, Bohstedt, Deobald, & Wegner, 1939). Attempts to manage the N release rate of dietary urea in the rumen with other forms of NPN (Bergner, Görsch, Wiesner, & Willer, 1977) suggests that N supply to the rumen may have been through rumeno-hepatic circulation, as proposed earlier (Egan & Moir, 1965). Additional studies described the effects of short-term duodenal infusion of urea in sheep fed low-protein, high-forage diets, showing improvements in feed intake and digestibility as well as improved N balance (Egan, 1965;Egan & Moir, 1965).…”