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 food source for humans. 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


Each update contains changes meant to improve the accuracy of model predictions, utility to leverage updated knowledge on cattle nutrition, and ease of use for users. The following outlines the most recent updates to the CNCPS:

Version 7 update

Efforts from the Cornell group and collaborators have led to the development of CNCPS v7, creating new, and revising current, predictions for nutrient flows and animal requirements. Major updates to the current platform include: 

  • Temporal representation of nutrient flows throughout the gastrointestinal tract based on user described meals for the animal modeled. Results will provide maximum and minimum rates and concentrations of nutrients, giving users a better indication of nutrient status for the animal modeled. 
  • Representation of the complete gastrointestinal tract to allow for estimation of total tract digestibility of ingredients fed. 
  • Disaggregation of the integrated fiber degradation rate for forage ingredients, creating separate ‘fast’ and ‘slow’ fiber pools, each with their own rate of degradation. This revision looks to promote improved resolution of fiber digestibility in the rumen and energetic status in the animal. 
  • Inclusion of protozoal metabolism and nutrient composition in the rumen submodel to better represent microbial nutrient flow, with particular emphasis on amino acids. 
  • Inclusion of endogenous nitrogen supply, and subsequent demands, along the gastrointestinal tract to properly account for nitrogen status in the ruminant. An updated equation for nitrogen recycling has been included. 
  • Consideration of alternative measurements for intestinal digestibility of nitrogen in non-forage, low fiber ingredients which are ill-represented by the detergent system (i.e., neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN)).  
  • Updated, variable efficiencies of use for essential amino acids toward maintenance and other productive purposes. 

No standalone software will be made available for CNCPS v7, and licenses are not available for purchase by individual users (as they are currently with version 6.5). Users are encouraged to look for this technology, once available, in commercial software which makes use of CNCPS technology.

Version 6.5.5

The CNCPS v6.5.5 is currently utilized by commercial software platforms and is also available for purchase by individual users.  

Most recent updates to v6.5.5 include: 

  • Updates to predictions for energy, protein, and amino acid supply  
  • Extensive changes to the CNCPS Feed Library
    • Updated classifications of feed fractions
    • Rates of degradation 
    • Sensitivity of inputs towards model predictions

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 software utilizing CNCPS technology. 

These changes are further described in the following publications: 

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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