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Rumen Metabolism and Absorption of a ¹⁴C-Labeled Elastomeric Copolymer and its Value as a Roughage Substitute for Cattle^1,2,

Kansas State University, Manhattan 66506

Abstract

Several synthetic elastomeric and plastomeric polymers were tested for suitability as artificial roughages. They were fed to rumen-fistula ted cattle fed grain only. Several of the polymers were regurgitated, remasticated and reswallowed, and they formed thin strands of intermeshed fiber that produced a large, loosely woven hay-like mass that floated on the rumen contents. An elastomeric polymer consisting of copolymers of 80 to 90% ethylene and 10 to 20% propylene, with a tensile strength at yield of 45.7 kg/cm², a hardness of 30 units (Shore D hardness scale) and a tensile strength at 300% elongation of 51.0 kg/cm², was selected for further testing. The copolymer was fed at about 90 g/head daily for 127 days to cattle fed grain only. At slaughter, rumens contained an average of 8.0 kg copolymer (dry basis). Cattle fed the copolymer had healthier rumen papillae and epithelia of the abomasum and small intestines than did control animals fed grain only. Using ¹⁴C-labeled copolymer, we found that the copolymer was not degraded by rumen microorganisms or acid-pepsin solution. When ¹⁴C-labeled copolymer was fed to milking cows, no ¹⁴C activity was found in milk, blood or urine. Upon slaughter, about 100% of the ¹⁴C activity was recovered from digesta and feces. We concluded that the copolymer was not absorbed from the digestive tract.

¹ Contribution 80-274-J, Ruminant Nutr. Group, Dept. of Anim. Sci. and Ind., Kansas Agr. Exp. Sta.

² Supported in part by a grant from Exxon Research and Engineering Co., Linden, NJ 07036. The authors thank Dr. Dell Allen, Kansas State Univ., for grading the carcasses; Dr. I. J. Gardner, Exxon Chemical Co., for his assistance in the preparation of the 14C-labeled copolymer, and Dr. A. J. Rutkowski of Exxon, for his assistance in the design of the absorption-residue experiments. Our special thanks go to Drs. P. L. Malloy and R. H. Salvesen of Exxon for furnishing the copolymers and for their valuable assistance in the design and conduct of the experiments.

³ Present address: Lilly Research Laboratories, Elanco Products Co., Fresno, CA.