The Cornell Net Carbohydrate and Protein System (CNCPS) was developed to predict requirements, feed utilization, animal performance and nutrient excretion for dairy and beef cattle using accumulated knowledge about feed composition, digestion, and metabolism in supplying nutrients to meet requirements.

Model Purpose

Ruminants are utilized to convert feed nutrients to human food under widely varying conditions around the world and are a major source of human food nutrients. The goals of improving ruminant nutrition are to improve productivity, reduce resource use, and protect the environment. Further improvements in ruminant production efficiency will result from the use of models to predict nutrient requirements and feed utilization in specific production settings. Accurate prediction of nutrient requirements and supply enable the nutritionist to identify more of the variation in cattle performance than less comprehensive approaches to ration formulation.

Model Predictions

  • Energy, metabolizable protein, amino acid, and mineral requirements for maintenance, tissue deposition, and milk synthesis
  • Prediction of intake and ruminal degradation of feed carbohydrate and protein fractions, and microbial growth
  • Prediction of intestinal digestion and excretion
  • Prediction of metabolism of absorbed energy, protein, and amino acids
  • Prediction of nutrient excretion and feed requirements, individual and herd


The current version of the CNCPS model is designed to formulate for and evaluate multiple groups on a dairy farm and to further evaluate nutrient excretion and efficiency of use of nutrients. Each new version contains changes that improve the accuracy of the CNCPS model and user friendliness of the computer software.

Version 6.5.5 Update

We are pleased to announce an update to CNCPS version 6.5 that now includes NASEM 2021 updates for vitamins and minerals.  In addition to the existing bioavailabilities of vitamins and minerals, users will also receive NASEM 2021 bioavailabilities for all feedstuffs within the CNCPS Feed Library. Updated requirements of vitamins and minerals from NASEM 2021 have also been added and can be viewed in tandem with previous requirements.

CNCPS for Cattle (version 6.5.5)

Given the evolving nature of the model, we anticipate some updates over the next year or two within the current structure that will include updated feed amino acid profiles and characterizations in the library and an updated growth model for dairy replacements that includes the calf with the capacity to formulate starting at birth. There will also be further updates to lab procedures over the next year that will be reflected in the model. A more extensive discussion will follow as the model is finalized. At this time we expect that updates will be included in the current price.

Previous Versions

Significant changes to the feed library, feed chemistry and function of the program were made in version 6.5 and farm files created in version 6.1 or earlier may not be used.  Version 6.1 license holders may upgrade to the new release at no charge.  Version 5.0 is no longer supported and license holders are encouraged to purchase the current version.

For More Information

License and purchasing information

  • cncpscattle [at]

Feed chemistry and library inputs

  • vanutritionlab [at]

Diet or ration formulation questions

  • Mike Van Amburgh (mev1 [at]
  • Tom Overton (tro2 [at]
  • Larry Chase (lec7 [at]

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