The chapter "Nutrient Requirements of Beef Cattle" by Ronald J. Gill and Dennis B. Herd emphasizes the importance of meeting nutritional requirements to maintain optimal performance in growing, finishing, and breeding beef cattle. It highlights the need for producers to consider both actual performance and the economic impact of feed inputs. The authors provide tables (Tables 1 and 2) listing nutrient requirements for various classes and weights of animals, which can be used to calculate the most economical rate of gain. They also discuss the relationship between different methods of expressing feedstuff energy content, such as total digestible nutrients (TDN), gross energy (GE), digestible energy (DE), metabolizable energy (ME), net energy for maintenance (NEm), and net energy for growth (NEg). The chapter explains how to estimate nutrient intake based on forage consumption and supplement formulation to improve diet efficiency. For finishing cattle, complete diets are used, while for breeding cattle, management programs that separate animals based on stage of production, age, and body condition are crucial. The authors also provide guidelines for mineral and vitamin supplementation and emphasize the importance of minimizing costs and optimizing returns through efficient feed utilization.The chapter "Nutrient Requirements of Beef Cattle" by Ronald J. Gill and Dennis B. Herd emphasizes the importance of meeting nutritional requirements to maintain optimal performance in growing, finishing, and breeding beef cattle. It highlights the need for producers to consider both actual performance and the economic impact of feed inputs. The authors provide tables (Tables 1 and 2) listing nutrient requirements for various classes and weights of animals, which can be used to calculate the most economical rate of gain. They also discuss the relationship between different methods of expressing feedstuff energy content, such as total digestible nutrients (TDN), gross energy (GE), digestible energy (DE), metabolizable energy (ME), net energy for maintenance (NEm), and net energy for growth (NEg). The chapter explains how to estimate nutrient intake based on forage consumption and supplement formulation to improve diet efficiency. For finishing cattle, complete diets are used, while for breeding cattle, management programs that separate animals based on stage of production, age, and body condition are crucial. The authors also provide guidelines for mineral and vitamin supplementation and emphasize the importance of minimizing costs and optimizing returns through efficient feed utilization.