IN-VITRO DEGRADATION OF AMINES BY RUMEN MICROORGANISMS

Degradation of biogenic amines was studied in rumen contents obtained from wether sheep adapted to diets with different levels of biogenic amines: high (H), low (L) and without (W), containing 7.4, 2.4 and 0 g amines/kg dry matter (DM), respectively. To 200 g of the rumen contents (RC), 2 mi of a solution containing a mixture of the biogenic amines: cadaverine (73.5 mmol/l), histamine (45.0 mmol/l), putrescine (83.0 mmol/l) and tyramine (123.5 mmol/l) were added, followed by a 5 h incubation in vitro. The fermentation pattern in RC derived from H and L differed from that in RC derived from W. This difference was attributed to differences in fermentative properties of silage and hay-based diets in the rumen. The addition of amines increased ammonia production, which was highest in RC from sheep adapted to silage with the highest amine content (diet H). Amines had no influence on gas production. Amine degradation occurred in all types of RC, but the extent depended on adaptation of the rumen microflora, such that 70.9, 54.2 and 25.3 % of the added quantity in RC from H, L and W, respectively, was degraded. Generally, the breakdown of the individual amines was highest for histamine, followed by tyramine, putrescine and cadaverine. Tyramine breakdown was particularly slow in RC from diet W. These results imply that in animals adapted to grass silage with high concentrations of biogenic amines, the accumulation of amines in the rumen will be prevented by an increase in the amine-degrading capacity of the rumen microbes.