Effect of liveweight and pasture height on cattle bite dimensions during progressive defoliation

Five experiments each with a different forage species (wheat, oats, forage sorghum, millet, and lucerne) were performed to determine the effects of cattle liveweight and pasture height, created by progressive defoliation, on bite dimensions and bite weight. In each experiment, 3 levels of liveweight and 3 levels of initial sward heights were used. Sward height had a positive effect on bite depth and bite area, although the effect on bite weight differed among forage species. In general, the effect of liveweight on bite dimensions was not significant. It is concluded that bite area and bite weight are determined principally by pasture structure (e.g. height and bulk density) rather than by mouth dimensions. According to our results, when forage intake or ingestive behaviour are to be explained, pasture measurements should describe successive horizons equal to 50% of pasture height to reflect the bite depth measured in cattle. Also, the results indicate that lighter animals could get a nutritional advantage since they may achieve a relative high bite weight per kg liveweight.