Melamine as a Dietary Nitrogen Source for Ruminants

Abstract

Three trials were conducted to determine the usefulness of melamine as a dietary non protein nitrogen (NPN) source for cattle. Ruminally fistulated steers were fed diets in which the supplemental protein was provided by either cottonseed meal, urea or melamine. Rumen fluid was sampled for ammonia concentration periodically for 7 hr after feeding on six occasions during the first 49 days. After 88 days the steers fed cottonseed meal and melamine were fasted for 48 hr then refed and ruminal ammonia concentrations monitored. In vitro rumen ammonia concentrations produced by inoculation of either a cottonseed meal, urea, melamine or control (no supplemental nitrogen) substrate with rumen fluid from the steers fed either cottonseed meal or melamine were monitored. Results of these ammonia concentration trials indicated that melamine was slowly hydrolized in a ruminal environment. A 3 × 3 replicated Latin square digestion and nitrogen balance trial was conducted using the three diets previously fed to the fistulated steers. Results indicated that melamine had little effect on the digestibility of dietary components. Melamine nitrogen was apparently digested to an extent equal to cottonseed meal nitrogen but not (P<.01) as completely as urea nitrogen. Larger (P<.05) amounts of nitrogen fractions other than ammonia and urea appeared in the urine when melamine was fed than when cottonseed meal or urea was fed. Nitrogen balance was lower (P<.05) for melamine than cottonseed meal and tended to be lower than for urea. Under the conditions of these trials, melamine may not be hydrolized in the rumen at a rate sufficient to promote maximum ruminal protein synthesis and incompletely hydrolized fractions may be absorbed and voided in the urine. These observations would tend to indicate that melamine may not be an acceptable NPN source for ruminants.