Fermentation and passage rate in the rumen and along the entire gut were measured in black Bedouin
and Swiss Saanen goats fed a high fiber diet (Rhodes grass (Chloris guyana) supplemented
with 10% alfalfa hay). The purpose of the study was to clarify the physiological basis that underlies
advantages of Bedouin goats over non-desert goats in digesting high fiber based diets. Volume of fluid
and rumen digesta particle distribution were similar for both breeds. Ability of Bedouin goats to consume
amounts of hay equal to those consumed by Saanen goats, despite considerably longer retention
time in the rumen, was related to their ability to maintain a higher digestion rate in the rumen. Microbial
activity in the particulate fraction was higher in Bedouin goats than in Saanen goats, and this was
reflected in total rumen fermentation, i.e., in significantly higher volatile fatty acid production rate
and significantly higher volatile fatty acid concentrations. The ability of Bedouin goats to maintain a
high fermentation rate in the rumen may be partially related to their ability to control rumen pH
above levels which cause severe depression in rate of fermentation. The combination of higher fermentation
rate and slower passage allows maximization of feed intake and digestibility in a given
situation, as compared to non-desert ruminants.