Effect of Feeding Lyophilized Rumen Contents on Adaptation to Urea Diet by Lambs

Eight Hampshire ram lambs (four controls and four inoculated) weighing approximately 30 kg were used to study the effects of lyophilized rumen fluid from urea-adapted donors on adaptation to dietary urea. A 12% crude protein diet containing 40% wheat straw was used. Urea furnished 31% of the total dietary nitrogen. Four mature Rambouillet ewes served as sources of “adapted” flora. Rumen contents were collected by stomach tube and freeze-dried. Thirty grams of lyophilized rumen fluid were fed to each of the treated lambs as a top dressing on day 1. Seven-day nitrogen balances were determined beginning on day 1 and 16 after inoculation. Nitrogen retention was similar for the two groups during the first 7-day (1.50 vs 1.65 g/day). Both groups showed marked improvement in nitrogen retention during the second period. Controls exhibited higher values than the inoculated lambs (5.50 vs 4.59 g/day), although the differences were not significant. Percent retention of absorbed nitrogen was higher in the control group during both collection periods. Nitrogen digestibility was approximately 66% for both groups. There was no significant difference in DM digestibility between treated and control lambs.