Studies on analysis of passage rates of digesta in ruminants fed roughage
2001
Oshita, T. (Tohoku National Agricultural Experiment Station, Morioka (Japan))
The objective of the present study was to assess the usefulness of rare earth elements as particulate phase markers for the estimation of passage rates of digesta in sheep fed roughage and to clarify the effects of forage factors on passage rates. The dissociation rate of rare earth elements from original labeled feed material in the digestive tract was less when the feed was labeled by the immersion technique than by the spray technique. Percentages of Dy released into the supernatant from the originally labeled hay was 1 - 3%. The maturity of timothy hay affected the ruminal passage rate, and nitrogen supplementation improved digestion of forage fiber but did not affect the rate of passage of particulate digesta through the rumen. The effects of chopping length and dry matter intake of forages on chewing activity and passage rates of digesta in ruminants vary with the forage species. In conclusion, the measurement of passage rates using the rare earth elements as particulate phase markers is very useful for the analysis of digestion dynamics in ruminants. The results showed that the passage rate of digesta in ruminants fed roughage varies according to the kinds of roughage source and is strongly affected by the ease of particle size reduction of digesta, which is closely related to the morphology of the plant and the physico-chemical structure of the cell wall.
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