Updates to the Cornell Net Carbohydrate and Protein System v6.1 and implications for ration formulation

Abstract

The Cornell Net Carbohydrate and Protein System (CNCPS) has been in development for nearly 30 years, and various versions of the CNCPS or implementations of the program (CPM Dairy, AMTS.Cattle, NDS, DinaMilk) have been used in the dairy industry to evaluate and formulate rations for more than 10 years. The long-term objective of the CNCPS modeling effort has been to provide a field usable model that accounts for a large proportion of the variation in ration formulation and animal performance and is based on a functional mathematical description of the biology of both growing and lactating cattle and their diet and management. Models such as the CNCPS are evolutionary in that as research progresses, model improvements and enhancements occur, provided adequate resources are available for programming and evaluation. This process is similar to the process that occurs when a new Nutrient Requirements of Dairy Cattle publication is produced. Unlike the NRC publications, historically published every 10 years, the CNCPS has been updated on a somewhat continuous basis. Each update has allowed us to predict performance with increased accuracy. However, these updates have at times, caused confusion in the field. This confusion is a combination of changing guidelines and a lack of awareness as to what the changes were and why/how they impact predictions. The objective of this paper is to describe recent updates and explain what impact they have on predictions.