In vitro batch cultures of rumen microorganisms were performed with or without polyethilenglycol (PEG) to study the effect of this tannin-binding agent on the rumen bacterial community. Six cannulated sheep were divided in two groups and fed only forage or a total mixed ration with 60% of concentrate. Rumen fluid was collected in two different days from these animals to obtain one inoculum per diet and day (4 in total) for the batch cultures of maize. After 22 h of incubation, microbial DNA was extracted and then analyzed by terminal restriction fragment length polymorphism. The bacterial profiles clustered basically according to the day of rumen fluid collection and the diet, suggesting that the bacterial community structure was not affected by PEG. On the other hand, the relative frequency of some fragments varied with PEG addition. Thus, for instance, fragments compatible with Butyrivibrio spp., which may tolerate or even degrade tannins, showed a lower proportion with PEG. However, this effect was only significant with the inocula derived from animals fed forage. The remarkable differences between days in the rumen bacterial composition of the same sheep on the same diet, especially in those fed the total mixed ration, might have precluded the detection of further PEG effects on specific bacterial populations.

3 páginas, 1 figura, 1 tabla.-- Trabajo presentado al III Simposio sobre Microbiología Digestiva (Zaragoza, 19 de mayo de 2011).

Peer reviewed