New NRC Nutrient Requirements of Swine Publication

Livestock Update, June 1998

Allen Harper, Extension Animal Scientist, Swine, Virginia Tech

This spring the National Research Council (NRC) committee on swine nutrition unveiled the tenth edition of the Nutrient Requirements of Swine publication. This edition replaces the ninth edition published ten years ago. Swine nutritionists, feed formulators and others in the swine feeding business have anxiously awaited the arrival of the new NRC for swine. Most felt that the 1988 version was very outdated with only limited application to current swine feeding practices.

A major disadvantage with the former swine NRC publication is that it provided a static set of recommended minimum nutrient levels for given weight classes of growing pigs, gestating sows or lactating sows. This limited application because many factors including sex (barrows vs. gilts), pen space, genotype, energy density of the diet, and environmental temperature can impact minimum nutrient requirements of different classes of pigs. The new NRC addresses this limitation by using a modeling approach to predict amino acid requirements for various classes of swine. Included with purchase of the tenth edition is a comprehensive booklet and a CD-ROM disk (or a set of floppy disks). The printed booklet includes extensive text and tabular information but the model information on the disk is all that is required to generate recommended nutrient requirements for various classes of swine. There are three basic models included: a growing pig model for pigs from 20 kg (44 lb.) to market weight, a gestating sow model and a lactating sow model. Suggested requirements for young weanling or starter pigs less than 20 kg are included in the printed text but not in the model program.

The growing pig model uses a lean growth accretion curve to predict dietary amino acid requirements under selected production and performance conditions. A standard lean growth curve is used in the model by default or the user can apply another curve if they have determined one for their own pigs or conditions. The user selects certain conditions such as the weight category of the pigs, the sex or sex ratio of the pigs and the energy density of the diet and the model generates suggested dietary amino acid and protein levels based on the selected conditions. The user may also change environmental temperature conditions and stocking density in the model inputs to refine nutrient requirements as these conditions change. In addition to predicting amino acid requirements, the output provides estimates of expected feed intake and feed efficiency, and recommended dietary levels for specific vitamins and minerals.

Procedures for using the gestating and lactating sow models are similar to the growing pig model. However, in these models the user inserts information related to sows such as daily energy consumption, dietary energy level, breeding weight, expected gestation weight gain, sow weight after farrowing, sow weight change during lactation, number of pigs nursing, and nursing piglet weight gain. The model program then predicts the dietary amino acid needs and also provides mineral and vitamin needs.

Additional items in the new tenth edition of the swine NRC publication are expanded feed composition tables, a new chapter on waste nutrient management, and updated chapters on mineral, vitamin and water requirements. The new addition reads easily and is computer user "friendly." To run the computer models, hardware requirements include an IBM compatible computer with an 80386sx (or higher) processor, a mouse, 8 Megabybes of random access memory, 16 Megabytes of hard disk drive space and a CD-ROM or floppy disk drive. Software requirements include Windows version 3.1 or higher.

The tenth edition of Nutrient Requirements of Swine is available from the National Academy Press, 2101 Constitution Ave., NW, Lockbox 285, Washington, DC 20055. The basic cost per copy is $39.95.

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