Proposal to use time spent chewing as an index of the extent to which diets for ruminants possess the physical property of fibrousness characteristic of roughages

Abstract

1. Previous publications by the author and his colleagues have provided extensive records, and additional ruminating behaviour of cows receiving a wide range of diets. These recoreds, and additional unpublished records, have been used to justify a proposed index of the physical property of fibrousness, or roughage, in diets for ruminants. 2. It is proposed that the total time spent by ruminants in chewing their food, during eating and during ruminating, should be the basis of the basis of the roughage index 3. Experssion of the roughage index as total time spent chewing per kg dietary dry matter largely eliminates differences resulting from variation in the amount of food consumed, and differences resulting from the time of access to the food. 4. Examples of the proposed roughasge index are given. The values range from 145 to 191 min/Kg dry matter for oat straw ot under 20 min/kg dry matter for diets of concentrates or of finely ground herbages; hays and silages tend to fall in the region of 90–110 min/kg dry matter. Values for the indx increase with dietary proportaions of hay or straw.