Comparison of rate of passage, fermentation rate and efficiency of digestion of high fiber diet in desert Bedouin goats compared to Swiss Saanen Goats

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.