Comparison of Bite-Count and Rumen Evacuation Techniques to Estimate Cattle Diet Quality

Abstract

We conducted a study to compare the bite-count technique (BC) of estimating forage intake and synthesized diet quality to direct estimates of diet quantity and quality with the use of the rumen evacuation technique (RE). We used four rumen-fistulated steers to evaluate both techniques. Four enclosures in a mixed-conifer rangeland were used. Each enclosure contained two 0.25-ha paddocks that were either nonstocked or stocked by cattle to remove 32+/-4% of standing crop. We recorded bite-count data during foraging bouts for each steer in each paddock, and then evacuated each rumen following each foraging bout during summer (August). Paddocks stocked prior to each 20-min trial had a reduced (P<0.05) quantity offorage consumed regardless of technique. BC and RE gave similar (P>0.10) results on diet quantity and digestibility. However, BC-derived estimates were lower (P<0.05) for crude protein (CP), acid detergent fiber (ADF), ash, and neutraldetergent fiber (NDF). In summary, although BC has the advantage of not requiring rumen-fistulated animals, it did not yield comparable results to RE under range conditions with dense and diverse vegetation. Therefore, investigators should calibrate bite-count technique against fistula technique to solve any accuracy problem in their specific experimental conditions whenever possible.