Maintaining Deer Rumen Fluid for in Vitro Digestion Studies

Effects of time between collection of inoculum and initiation of in vitro digestion and effects of method of storage and temperature of the inoculum upon in vitro digestion of a ground alfalfa sub- strate were examined. There was a significant decrease ( P < 0.05 ) in digestion of dry matter after stor- age of rumen inoculum from mule deer ( Odocoileus hemionus) for more than 2 hours. In vitro digestion of dry matter was greater when inocula were stored at 38.5 C than at 7 C. Inocula strained through cheesecloth and stored without buffer produced higher dry matter digestion than was produced by either inocula strained and stored with buffer or with unstrained unbuffered inocula. Wildlife biologists have adopted tech- niques of in vitro digestion for measuring the nutritional values of forages used by wild ruminants. Captive, sometimes rumen- fistulated, animals are often used as donors of rumen inoculum. However, research objectives may dictate that inoculum be obtained from wild animals far from the laboratory. The collection of inoculum from field animals may require that rumen fluid be in transit for several hours; during the time ill transit the quality of the inoculum is expected to change. This paper describes the effects of the time between collection of inoculum and initiation of in vitro digestion and the effects of the techniques of storing the inoculum and storage temperature of the inoculum upon in vitro digestion of a ground alfalfa substrate. We thank Drs. J. A. Bailey and O. C. Wallmo and W. L. Regelin for review of the manuscript.