Publisher Summary
This chapter describes the protein requirements of beef cattle. The calculation of protein allowances is based upon the sum of three functions which require protein: maintenance, unavoidable losses of protein in the feces, and production. Proteins are a very complex group of compounds that contain carbon, hydrogen, oxygen, nitrogen, and in some cases, sulfur. Hydrolysis of protein produces free amino acids. The chapter discusses the role of protein, its digestion, and nonprotein nitrogen (NPN) in detail. An elaborated insight into various topics like protected or slowly degraded protein; effects of protein supplementation on the performance of growing and finishing cattle; protein and amino acid requirements of beef cattle; and protein adjustment during temperature stress is also provided. Research studies involving high ruminally undegradable protein (RUP) supplements have shown that feeding bypass proteins in combination with urea improved the growth rate or feed efficiency compared with feeding soybean meal or urea alone. Growing and finishing beef cattle require minimal levels of dietary protein, which are a function of live weight and rate of gain. Diets containing corn and corn silage probably require supplemental protein for optimal growth rate. The most common environmental factor that alters nutrient requirements is temperature. Environmental temperature affects the growth rate.