Mechanical stimulation of rumination in sheep by the intraruminal addition of inert fibre particles

Inert fibre particles were used in a series of experiments in order to quantify the effects of some physical characteristics of dietary long fibre on rumination. Removal of hay from the diet of hay/concentrate-fed sheep reduced true rumination to zero after a period of 8 days, although pseudorumination, much reduced in duration, persisted. Then by introducing loose, chopped, inert polyethylene particles through a rumen cannula, rumination was restored. When different masses of loose inert polyethylene particles chopped into 10-mm lengths were placed in the rumen, the time spent ruminating was found to be directly proportional to mass of fibre placed in the run ren (P < 0 . 001). By inserting a fixed mass of particles of different lengths, the optimum length of inert fibre for rumination to occur was found to lie between 7 and 30 mm. Finally, when, in place of loose fibre, a polyethylene fibre 'pompom', fixed on a rod, tons introduced via the cannula and placed so as to brush different areas of the reticulorumen, it was found that the greatest rumination response was evoked when the pompom was allowed to stimulate mechanically the cranial regions of the reticulorumen (P < 0 . 05). It is concluded that inert polyethylene fibre mimicked the peripheral excitatory effects of dietary fibre by stimulating mechanoreceptors (epithelial receptors) located in the cranial portions of the reticulorumen. Adding about 50 g of 7 to 30 mm inert fibre caused sheep on low-fibre diets to ruminate normally for over 3 h.