Rumen Digestion in the Bovine with Some Observations on the Digestibility of Alfalfa Hay

Abstract

The importance of rumen digestion has been recognized for a long time but it has been only within recent years that dependable experimental evidence pertaining to tureen physiology has been obtained. Even now, little is known of the significance of rumen digestion when compared with the total digestion that occurs in the passage of feeds through the digestive tract. Recently, however, in vivo chemical studies of the digestion of various nutrients within the rumen have been undertaken. Silver (1) Studied the digestion and absorption of alfalfa hay by removing the rumen contents at the time of feeding and at 2-hour intervals thereafter. He interpreted his results by comparing the various values for percentage composition of the rumen contents as the period of digestion progressed. Kick and Gerlaugh (2) studied the effect of the preparation of alfalfa hay on tureen digestion and reported the percentage of the total daily intake that was represented by the rumen ingesta when removed 24 hours after feeding. In both of these investigations it was found that protein disappeared rapidly from the rumen while fiber disappeared slowly. Quittek (3) and Krzywanek and Quittek (4) compared the percentage composition of the rumen contents removed at 3-hour inter~/als with that of the hay. They observed that the percentages of nitrogen, crude fiber and crude fat in the dry matter of the rumen increased as digestion progressed. The increase in these nutrients was attributed to the rapid disappearance of carbohydrates by rumen fermentation. Although all of these methods have served a purpose, they are inadequate in making studies of rumen digestion because the results can only be interpreted on a comparative basis and no idea of the quantitative digestion can be obtained.