Abstract 94

Allison,MJ; Hammond,-AC; Jones,-RJ

National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50010 USA.

Applied-and-EnvironmentalMicrobiology. 1990, 56: 3, 590-594; 19 ref.

Leucaena leucocephala, a tropical leguminous shrub, contains a toxic amino acid, mimosine. Successful utilization of leucaena as a ruminant forage depends on colonization of the rumen by bacteria that degrade dihydroxypyridines (DHP), which are toxic intermediates in the metabolism of mimosine. Populations in the rumina of animals in some parts of the world, however, do not include bacteria that are able to carry out this degradation. Tests for the presence of DHP degraders in ruminal populations that are based on degradation (loss) of DHP compounds from culture media are described. Results obtained with the tests indicate that DHP degraders were not part of microbial populations in the rumina of cattle, sheep, and goats in Iowa, while most rumen samples examined from animals from the Virgin Islands and Haiti contained DHP degraders. These results confirm and extend the findings of others about geographic limits to the distribution of these important ruminal bacteria.