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The 7th revised edition of the Nutrient Requirements of Dairy Cattle was published in 2001 by the National Research Council (NRC) through the National Academies Press as part of the long-standing Nutrient Requirements of Domestic Animals series.

Developed by the NRC Subcommittee on Dairy Cattle Nutrition under the Committee on Animal Nutrition, this edition synthesized the scientific literature available at the time to provide an authoritative consensus on the nutrient needs of dairy cattle. It built on earlier editions dating back to the 1940s and served as the primary reference for dairy nutrition research, teaching, and practice for nearly two decades, until the release of the next major revision in 2021.

The 2001 Dairy NRC advanced the field by integrating biologically based prediction equations for dry matter intake, energy, and protein utilization across life stages, including calves, heifers, dry cows, and lactating cows. It provided detailed recommendations for energy, metabolizable protein, minerals, vitamins, and water, while explicitly linking nutrient supply to milk production, body condition, and animal health. Importantly, the publication was accompanied by a computer model distributed on CD-ROM, enabling users to apply NRC equations dynamically rather than relying solely on static tables. This combination of conceptual rigor and practical decision-support capability made the NRC Dairy 2001 a cornerstone reference for ration formulation, research evaluation, and extension programming in modern dairy production systems.

Since 1945, the NRC has published eight editions of the Nutrient Requirements of Dairy Cattle. The 8th Revised Edition, released in 2021, represents the most recent comprehensive update of this series. The evolution of the Nutrient Requirements for Dairy cattle is discussed below.

Revision History (Tedeschi et al., 2019):

• Origins (1945). The Nutrient Requirements of Dairy Cattle began with the publication of the Recommended Nutrient Allowances for Dairy Cattle in 1945 by the NRC. Early recommendations were empirical in nature, based primarily on feeding trials and production responses, reflecting the limited mechanistic understanding of nutrient utilization at the time.
• Early revisions and conceptual shift (1950–1956). The first revision was issued in 1950, followed by a second revision in 1956, when the publication was retitled Nutrient Requirements rather than Recommended Nutrient Allowances. This change marked a conceptual transition toward defining biological requirements, with particular emphasis on dietary protein concentrations to support increasing milk production.
• Expansion of physiological knowledge (1966). The third revision in 1966 reflected growing insights from digestion and metabolism research. Although requirements were still largely expressed as dietary concentrations, distinctions among physiological functions such as maintenance and production became clearer.
• Adoption of net energy systems (1971). The fourth revision, published in 1971, incorporated the net energy system for dairy cattle, driven by advances in metabolism trials during the 1960s. This represented a major shift toward partitioning energy use among physiological functions and improving prediction of productive responses.
• Refinement of protein evaluation (1978). The fifth revision in 1978 introduced substantial changes to protein requirement calculations, incorporating concepts such as feed protein solubility and unavailable protein. These advances reflected increased scrutiny of rumen function and nitrogen utilization efficiency.
• Metabolizable protein framework (1989). The sixth revision, released in 1989, formally adopted the metabolizable protein system, recognizing ruminally undegraded protein and microbial crude protein as the principal sources of absorbable amino acids. This represented a fundamental departure from crude protein–based systems.
• Mechanistic modeling era (2001). The seventh revision, published in 2001, marked a major expansion in scientific scope and computational complexity. Enabled by digital computing and large experimental datasets, this edition introduced equation-based, mechanistic models to predict nutrient requirements for maintenance, growth, pregnancy, lactation, rumen fermentation, digestion, absorption, and metabolism. A companion computer model allowed dynamic application of NRC concepts beyond static requirement tables.
• Comprehensive modernization and sustainability focus (2021). The Eighth Revised Edition, released in 2021, built upon the 2001 framework by synthesizing two decades of advances in dairy nutrition, physiology, feed science, and environmental research. It expanded nutrient evaluation to include refined requirements for amino acids, lipids, carbohydrates, fiber, minerals, vitamins, and water across all life stages, while improving prediction of intake and performance under diverse environmental and production systems. The revision addressed contemporary issues such as mycotoxins, feed additives, coproducts from the biofuels industry, grain processing effects, rumen and metabolic modifiers, and antioxidant nutrition, and placed strong emphasis on reducing nutrient losses, mitigating greenhouse gas emissions, and improving nutrient-use efficiency. Where appropriate, updates to the NRC computer modeling framework were considered, reinforcing the role of decision-support systems in modern dairy nutrition (NASEM, 2021).

Across successive editions, the Dairy NRC evolved from empirically derived feeding guidelines to mechanistic, systems-based nutritional models. Progressive removal of conservative safety factors, improved representation of nutrient kinetics, and greater integration of animal–environment–diet interactions have enhanced precision in ration formulation, reduced environmental impacts, and strengthened the scientific basis for decision support in dairy production systems.

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			Visual Basic 6 (SP6)
The Nutrient Requirements of Dairy Cattle 7th Revised Edition (2001) included a companion computer model designed to allow users to apply the scientific equations and nutrient prediction framework described in the printed report directly to diet evaluation and animal requirement prediction. This software was distributed as part of the NRC 2001 publication and was intended to run on Windows operating systems of the early 2000s, providing a dynamic implementation of the NRC nutrient requirement system that extended beyond static tables. By enabling inputs for animal characteristics and diet composition, the program could simulate nutrient needs for dairy cattle across physiological states, incorporating the comprehensive energy, protein, mineral, vitamin, and intake prediction components embedded within the seventh edition. The downloadable model (approximately 6.8 MB) was accompanied by context-sensitive “Help” features to assist users in operating the software, but, as noted by the National Academies Press, it was offered without formal technical support or guaranteed accuracy, placing responsibility for interpretation and use on the individual user. Over time, changes in computing environments rendered the original 2001 NRC Dairy software less compatible with later versions of Windows. To address this, the National Animal Nutrition Program (NRSP-9) and the Nutrition Modeling Committee developed updated releases of the Dairy NRC model, culminating in version 1.1.11. This updated version includes a series of fixes and compatibility enhancements that enable the NRC Dairy 2001 software to run on modern Windows platforms including Windows 10 and Windows 11, while retaining the original scientific logic and functionality of the model. These community-driven modifications ensure that researchers, educators, and nutritionists can continue to use the NRC Dairy model on contemporary systems without the need for legacy hardware or emulation layers, extending the practical utility of the 2001 nutrient framework.

The current version of the 2001 Beef Cattle Nutrient Requirements Model is Loading...

Previous versions can be downloaded from here.

Changes to the Dairy NRC (2001) software are listed in this text file.

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No registration is needed for the current version. Nonetheless, you are welcome to submit your comments to improve this model at the Contact us web page.

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SUBCOMMITTEE ON THE 2001 DAIRY CATILE NUTRITION:
Jimmy H. Clark, Chair, University of Illinois, IL David K. Beede, Michigan State University, MI Richard A. Erdman, University of Maryland, MD Jesse P. Goff, USDA/ARS/NSDC, IA Ric R. Grummer, University of Wisconsin, WI James G. Linn, University of Minnesota, MN	Alice N. Pell, Cornell University, NY Chcarles G. Schwab, University of New Hampshire, NH Trevor Tomkins, Milk Specialties Company Gabriella A. Varga, Pennsylvania State University, PA William P. Weiss, The Ohio State University, OH

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The following list summarizes corrections, enhancements, and functional improvements made to the software, presented in chronological order (newest to oldest). Each entry reflects updates implemented to improve stability, usability, and overall performance.

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• National Animal Nutrition Program, National Research Support Project (NRSP-9) web site.
• 8th Revised Edition of the Nutrient Requirements of Dairy Cattle web page
• 7th Revised Edition of the Nutrient Requirements of Beef Cattle web page.
• 8th Revised Edition of the Nutrient Requirements of Beef Cattle web page.
• 2007 Nutrient Requirements of Small Ruminants web page.

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