Nutrient Requirements of Beef Cattle

Feed cost has been estimated to account for approxi¬mately 70% of the expenses associated with a beef cattle operation. The consequences of under- or overfeeding beef cows can be substantial. Underfeeding cows can result in thin body condition, poor reproductive performance, and poor milk production. On the other hand, overfeeding can be unnecessarily expensive, increase calving difficulty, reduce milk production, and potentially have a negative impact on the environment. To effectively balance diets, it is essential to know the nutrient requirements of the animal. Demand for nutrients can vary by numerous factors. However, the requirements defined in this publication will only address variability associated with animal size, stage of production, and milk production. When applying these requirements to cows in excessively cold or hot climates, adjustments will be neces¬sary to achieve predicted animal performance. Throughout this publication, all nutrient requirements are expressed as either % or parts per million (ppm) of the diet dry matter (DM). Parts per million may also be expressed as milligrams per kilogram (mg/kg). With the exception of water, nutrients are supplied to the animal only from the DM portion of the diet. As such, it is essential to convert the amount of each ingredient from an as-fed basis (AF) to a DM basis. A worksheet has been included at the end of this publication to facilitate that conversion.