Nutrition Models
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The Large Ruminant Nutrition System (LRNS) is a computer program that estimates beef and dairy cattle requirements and nutrient supply under specific conditions of animal type, environment (climatic factors), management, and physico-chemical composition of available feeds, using the computational engine of the Cornell Net Carbohydrate and Protein System (CNCPS) model as published by Fox et al. (2004).
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The SRNS model is the result of a joint collaboration among Texas A&M University, Cornell University, and Sassari University. The SRNS is a computer model to predict nutrient requirements of sheep and feed biological values on farms based on the structure of the Cornell Net Carbohydrate and Protein System (CNCPS) for Sheep.
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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 and sheep, using accumulated knowledge about feed composition, digestion, and metabolism in supplying nutrients to meet requirements.
The CPM Dairy is an applied mathematical nutrition model that computes dairy cattle requirements and the supply of energy and nutrients based on characteristics of the animal, the environment, and the physicochemical composition of the feeds under diverse production scenarios. It was designed as a steady-state model to use rates of degradation of feed carbohydrate and protein and the rate of passage to estimate the extent of ruminal fermentation, microbial growth, and intestinal digestibility of carbohydrate and protein fractions in computing energy and protein post-rumen absorption, and the supply of metabolisable energy and protein to the animal.
Growth and Development
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The CVDS was developed for use in individual cattle management for growing beef cattle. The CVDS provides (1) prediction of daily gain, incremental cost of gain and days to finish to optimize profits and marketing decisions while marketing within the window of acceptable carcass weights and composition, (2) predictions of carcass composition during growth to avoid discounts for under or over weight carcasses and excess backfat, and (3) allocation of feed fed to pens to individual animals for the purpose of sorting of individuals into pens by days to reach target body composition and maximum individual profitability.
Model Evaluation and Adequacy
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The MES was developed to assist on the adequate evaluation of mathematical models using statistical analysis, including linear regression analysis, mean square error of the prediction, concordance correlation coefficient, distribution analysis, deviation analysis, graphics and histogram, robust statistics, etc.
Fitting Models
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The GnG1 model was developed based on theoretical concepts and probability to generalize the rumen processes of fiber digestion. It can be used to interpret fiber degradation and passage profiles. The GnG1 model was evaluated for quality of fit using in vitro fiber degradation profiles and in vivo fiber passage profiles. The integration of digestion and passage is based on the concept that fibrous digesta in the rumen is heterogeneous (Vieira et al., 2007a,b,c).
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The in vitro gas production technique has been frequently used to assess biological values of feeds based on their pattern of accumulated gas during incubation with rumen fluid under anaerobic conditions. After data is collected, kinetic parameters that accurately describe the pattern of fermentation can be obtained. Several models have been described and used to fit in vitro gas production data to nonlinear functions (López et al., 1999). The GasFit System was developed to evaluate several nonlinear models in fitting gas production data.
Games
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The Hay Game is a stand-alone computer software based on the Beer Game. The Beer Game was developed to introduce students, managers, and executives to concepts of system dynamics. The purpose of the game is to illustrate the key principle that "structure produces behavior." Players of the Hay Game experience system complexity and provides insights of the long-term effects during the course of the game. The object of the Hay Game is to minimize the total cost of hay utilization in a farm.
Some modeling terminology can be found here.
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Download the image file (.ISO) of the distribution CD containing all nutrition models and support files. This is a large file with 620 Mb. |