Submitted to: Feedstuffs
Publication Type: Trade Journal
Publication Acceptance Date: 11/16/2017
Publication Date: 12/4/2017
Citation: Gunter, S.A. 2017. Predicting forage intake by grazing beef cattle. Feedstuffs. 89(12).
Technical Abstract: The control of feed intake by ruminants is complex, and developing a cohesive theory of intake control in ruminants continues to be a challenge. Because our understanding of factors that regulate intake by cattle is inadequate, predicting feed intake, even under the best of circumstances, is difficult. In grazing cattle, this difficulty is exacerbated by additional influences that can sway basic control mechanisms, including selective grazing, herbage mass, sward structure and composition, climatic and environmental factors, and the intricacies of the grazing process itself. The sheer complexity of intake control in ruminants and the associated lack of mechanistic models has led to a reliance on empirical approaches. Fisher (2002) suggested that empirical models, despite their frequent lack of intellectual elegance, have considerable merit, leading to many practical applications in beef cattle feeding. Generally, most empirical models in use today are based on the physical/physiochemical theory of intake regulation. Thus, intake of less digestible, low-energy diets is mostly controlled by physical factors like ruminal fill and digesta passage where intake of highly digestible, high-energy diets is mostly controlled by energy demands of the animal and by metabolic factors.