Diaminopimelic Acid Content of Feeds and Rumen Bacteria and Its Usefulness as a Rumen Bacterial Marker

Abstract

Several feeds were examined and most were devoid of diaminopimelic acid. Small amounts of diaminopimelic acid were in corn silage, sorghum silage, beet pulp, and two samples of alfalfa hay. Nine strains of rumen bacteria were grown in pure culture in rumen fluid media containing three concentrations of carbohydrate. After incubation, bacteria were harvested and analyzed for diaminopimelic acid and total nitrogen. Among bacterial species there were significant differences in the ratio of diaminopimelic acid nitrogen to total bacterial nitrogen when they were grown in media containing different concentrations of carbohydrate. Diaminopimelic acid nitrogen concentration ranged from none in Streptococcus boris to 1.61% in Ruminococcus flavefaciens. Six rumenfistulated cattle were fed either a highroughage (85% hay) or high-concentrate (85% concentrate) diet to study the effect of diet on diaminopimelic acid content of mixed rumen bacteria. Bacteria from cattle fed the high roughage diet contained more diaminopimelic acid nitrogen to total nitrogen (.65%) than those fed the high-concentrate diet (.50%). Time of sampling in relation to feeding had no effect on diaminopimelic acid nitrogen to total nitrogen content of bacteria. We concluded that to use diaminopimelic acid to predict bacterial production in the rumen accurately, it will be necessary to correct for dietary effects on diaminopimelic acid composition of bacteria.