DISTRIBUTION:
Trifolium spp. as well as Medicago spp. were imported from Europe and Asia to grow as fodder for stock. The Oudtshoorn district is responsible for about 90% of the lucerne seed produced in South Africa.
BOTANICAL DESCRIPTION:
Trifolium repens: Low growing, spreading plants with trifoliate leaves, sometimes mistaken for grass.
TOXIC PRINCIPLE:
Frothy bloat:
Saponins and glycoproteins.
MECHANISM OF ACTION:
• Soluble proteins escape rapidly from fragile thin-walled cells of above species during cellulose digestion.
• This results in changes in surface tension of ruminal fluid and stabilization of gas bubbles in rumen.
• Critical concentration of several surface-active agents leads to persistent, rigid foam.
Phyto-oestrogenism:
• The toxic principles of the clovers are various isoflavone glycosides, which are inherently oestrogenic and/or are biotransformed in the rumen to active or inactive compounds.
• The oestrogenic compounds contained in lucerne are coumestans.
SYNDROMES:
Frothy bloat, ABPE, Phyto-oestrogenism.
SYSTEMS AFFECTED:
Gastro-intestinal, urogenital and respiratory systems.
CLINICAL SIGNS:
Frothy bloat:
• Severe bloat, distended abdomen.
• Ruminal atony.
• Dyspnoea.
Phyto-oestrogenism:
• Infertility.
