|Van amburgh, M|
Submitted to: Animal Feed Science And Technology
Publication Type: Review article
Publication Acceptance Date: 8/31/2003
Publication Date: 12/31/2003
Citation: FOX, D.G., TEDESCHI, L.O., TYLUTKI, T.P., RUSSELL, J.B., VAN AMBURGH, M.E., CHASE, L.E., PELL, A.N., OVERTON, T.R. THE CORNELL NET CARBOHYDRATE AND PROTEIN SYSTEM MODEL FOR EVALUATING HERD NUTRITION AND NUTRIENT EXCRETION. ANIMAL FEED SCIENCE AND TECHNOLOGY. 2003. V. 112. P. 29-78. Interpretive Summary:
Technical Abstract: The Cornell Net Carbohydrate Protein System (CNCPS) is a mechanistic model that estimates animal requirements and nutrients supplied based on animal, environmental, and feed compositional information in unique production situations. Animal requirements are designed to account for different physiological states (lactation, pregnancy, growth), body reserves and environmental effects. The CNCPS uses feed carbohydrate and protein degradation rates to predict extent of ruminal fermentation, microbial protein flow, post-ruminal absorption, and the total supply of metabolizable energy and protein to the animal. The CNCPS has been used successfully on beef and dairy cattle farms to evaluate and formulate rations. When the CNCPS was evaluated with data from individual dairy cows and appropriate CNCPS inputs were measured, the CNCPS accounted for 90% of the variation in actual milk production of individual cows with a 1.7% bias. The model accounted for 56% of the variation in individual cow milk production with an 8.5% under prediction bias when energy was first limiting in high producing cows, and accounted for 77% of the variation with a 1.4% bias when protein was first limiting. The CNCPS has evolved into precision feeding and feed management tool that can be used to improve animal productivity, optimize ration costs, reduce nutrient excretion and decrease environmental pollution. To accomplish these latter objectives, the CNCPS has equations to predict N and P excretion, annual feed requirements, and manure production on a whole herd basis. When the CNCPS was used in this latter fashion in case studies on New York dairy farms, N and P in manure and purchased feed costs were reduced by as much as 1/3.