Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/1996
Publication Date: N/A
Citation: N/A Interpretive Summary: Ruminants have a fermentative type of digestion that is carried out by microbes in the first two compartments of the ruminant stomach and by a simple type of digestion (hydrolysis) carried out in the fourth compartment of the stomach and the small intestine. The amount of fermentative digestion that takes place can greatly influence the nutrient needs of ruminant animals, particularly protein needs. Therefore, it is important t be able to study the fermentative digestion apart from intestinal digestion. The sampling device described enables collection of digesta samples leaving the fermentative region of the stomach. This device has less adverse impact on the animal than the surgery needed to establish sampling portholes in the small intestine. Also, larger numbers of animals can routinely be assembled for experiments when the sampling device is used rather than when surgically modified animals are used. This contributes to more sensitive and accurate experiments.
Technical Abstract: Abomasal and duodenal fistulas in sheep and cattle have been used as digesta sampling sites to study fermentative digestion in the ruminant forestomach. In the present study, a procedure allowing digesta sampling from the omasum via a rumen cannula, without repeated entry into the omasum, was developed. The sampling system consists of a device inserted into the omasum via the rumen cannula, a tube connecting the device to the rumen cannula, and a single compressor/vacuum pump. Eight cows given ad libitum a total mixed ration were used in a switch-back design with three week experimental periods to evaluate the effects of the sampling system on digestive activity, animal performance and animal behavior. The results indicated that the omasal sampling system does not interfere with normal digestive and productive functions of high producing dairy cows. Dry matter intake was slightly reduced (24.0 vs 22.8 kg/d), but this seemed to be related more to the sampling procedures than to the device in the omasum. Observations of animal behavior indicated that cows with the sampling device were similar to control cows. The composition of digesta samples was biased towards an over-abundance of the liquid phase, but using a double- marker system to calculate digesta flow resulted in fairly small coefficients of variation for measurements of rumen digestion parameters. This technique may prove useful for partitioning digestion between the fermentative portion of the forestomach and the lower gastrointestinal tract. The omasal sampling procedure is less invasive than the traditional methods using abomasal or duodenal cannulas as sampling sites to study forestomach digestion, and avoids potentially confounding endogenous secretions of the abomasum.