CYTOTOXICITY IN MA-104 CELLS AND RUMEN PROTOZOA OF SOME PHYTOTOXINS AND THEIR EFFECT ON FERMENTATION BY FAUNATED AND DEFAUNATED RUMEN INOCULA

Toxic compounds present in plants are an important factor limiting the nutritional use of tropical legumes. This work deals particularly wit h the toxic nonprotein amino acid analogues mimosine, DOPA, and canava nine and structurally related compounds such as nicotinic acid, 3-hydr oxypyridine, and catechol. The effect of these toxins was measured on the viability of eukaryote cultured cells (MA-104) and rumen protozoa and on the fermentation activity (production of VFAs, ammonia, and gas ) by inocula from faunated and defaunated sheep in vitro. Toxins did n ot increase cell death of protozoa, while catechol and nicotinic acid increased cell death of MA-104 cells. Thus, these toxins affected diff erentially the viability of eukaryote cells. Mimosine, nicotinic acid, DOPA, and canavanine had a stimulatory effect on fermentation but inc reased accumulation of methane by faunated inoculum. Catechol drastica lly depressed the fermentation activity of faunated and defaunated ino cula and impaired the ammonia uptake by rumen microbes. Therefore, non e of these toxins would be suitable to eliminate protozoa, and they do not appear to improve the overall fermentation balance in the rumen.