Leucaena toxicosis and its control in ruminants

Area of Science:

• Animal Science
• Microbiology
• Toxicology

Background:

• Leucaena (Leucaena spp.) is a tropical legume used as livestock forage.
• Introduction outside its native range can cause toxicosis due to mimosine and its metabolite 3-hydroxy-4(1H)-pyridone (3,4-DHP).
• 3,4-DHP is a goitrogen, and its toxicity is linked to the absence of specific ruminal bacteria.

Purpose of the Study:

• To investigate the role of ruminal bacteria in leucaena toxicosis.
• To identify and introduce bacteria capable of degrading 3,4-DHP.
• To prevent leucaena toxicosis in ruminants.

Main Methods:

• Screening for 3,4-DHP degrading bacteria in ruminal samples and feces.
• Characterization of identified bacterial strains, designated Synergistes jonesii.
• Ruminal inoculation using enriched cultures or pure cultures of S. jonesii.

Main Results:

• Australian workers introduced 3,4-DHP degrading bacteria from Hawaiian goats to Australian livestock.
• Effective methods for detecting 3,4-DHP degraders were developed.
• Successful establishment of ruminal populations capable of degrading 3,4-DHP was achieved.

Conclusions:

• The geographical distribution of leucaena toxicosis is determined by the presence of 3,4-DHP degrading ruminal bacteria.
• Ruminal inoculation with S. jonesii is a viable strategy to prevent leucaena toxicosis in ruminants.