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New Version of Nutrient Requirements of Beef Cattle
Livestock Update, August 1996
Mark L. Wahlberg, Animal and Poultry Sciences
The National Research Council (NRC) has just produced and released the seventh edition of Nutrient Requirements of Beef Cattle. The last revision was published in 1984. I believe the current version makes giant leaps ahead in defining and quantifying the factors which influence the nutritional needs of beef cattle.
The document consists of two major components, a 242-page book and a computer diskette. In the book is 100 pages of literature review on 8 different major topics. A table of feed composition is included that gives not only average values but an estimate of the range in composition and the effects of processing methods .
There is approximately 70 pages in the book which is a users guide for the computer diskette. The diskette contains two different models that the user can choose. One is for evaluation and prediction of performance on a given diet, the other is to model the use of nutrients for various physiological processes. The computer models utilize current knowledge of factors which affect the nutritional needs of cattle and enables the user to define these factors to customize the situation for a specific feeding program. The user can print a table of requirements for the specific situation modeled.
The factors considered are amazingly detailed. For growing- finishing cattle they include:
| Description of the Animal and Environment | Description of Management |
|---|---|
| Age Sex Current Weight Breeding System Finished Weight and Grade Condition Score Additives & Implants | Pasture or Drylot Wind Speed Air Temperature Night Cooling? Hair Condition Heat Stress? Hide Thickness |
The factors for the Cow-Calf enterprise are:
| Description of the Animal and Environment | Description of Management |
|---|---|
|
Same as above plus ... Days Pregnant Days in Milk Lactation Number Peak Milk Production Duration of Lactation Milk Composition Age at First Conception Calving Interval Expected Calf Birth Weight | Same as Above |
Tables of nutrient requirements as structured in the 6th edition are not printed in the book. A table of requirements for an "average" animal are included, and the Appendix includes adjustment factors for most of the factors cited above. The computer method of determining requirements is strongly recommended, however.
This material is available from National Academy Press. See hard copy of Livestock Update for ordering information and price.
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