Conspecific body weight, food intake, and rumination time affect food processing and forage behavior

Much research has been directed at the chemical characteristics of plants that influence forage digestibility but there is less investigation into relationships between chewing and foraging in herbivores. The role of body size on forage processing, via chewing, and ingestive behavior is poorly understood in spite of associations between conspecific body size of ruminants and botanical and nutritional composition of their diets. I examined the implications from a relationship between body weight and absolute forage intake (kg/day) and no relationship between body weight and rumination time (h/day) on chewing behavior and feeding time (h/day). Cattle were selected as the model species because the diets presented offered benefits to digestion from increased chewing and because of the number of studies that measured body weight, daily food intake, dietary nutritional characteristics, feeding time, and rumination characteristics on the same individuals. Data were extracted from 24 studies of cattle (n ≤ 74). Absolute food intake scaled allometrically (0.75) with body weight but rumination time was unrelated to body weight, meaning smaller animals had more rumination time for a unit weight of ingesta. Correspondingly, small cattle chewed the weight-specific ingesta more and fed longer than large animals, probably because of a reduction in time of rumen turnover. These findings might be revealing as to how differences in digestion and foraging are associated with body size among conspecific animals of wild ruminant species.