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United States Department of Agriculture

Agricultural Research Service

Research Project: Sustaining Southern Plains Landscapes through Plant Genetics and Sound Forage-Livestock Production Systems

Location: Rangeland and Pasture Research

Title: Forage intake modeling and predictions for cattle grazing in extensive grazing environments

Authors
item Oltjen, James -
item Gunter, Stacey

Submitted to: Animal Production Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 31, 2014
Publication Date: N/A

Interpretive Summary: To be able to predict the performance of grazing cattle in extensive rangeland environments, herbage intake is paramount because it quantifies energy intake and performance. Nutrient demand of the animals has a major effect on forage intake and characteristics of the sward dictate how the animal will meet this demand. Estimates of herbage intake and parallel measurements of digestive behaviors of ruminants pose considerable challenges to researchers. Hence, advances in this area of research have been slow and costly. Simulation models predicting herbage that include weather, changing forage characteristics, and animal demand are needed to predict long-term beef herd performance and range forage conditions. Vegetation indexes captured from satellites can be used to accurately quantify the dynamics of forage production and changes in quality with confidence and has been shown to be consistently sensitive across a wide range of environments. The computer software, PCRANCH, is a program for simulating cow-calf herd dynamics over a long-time period. The PCRANCH software consists of three components: 1) the input interface which consists of range (physical characteristics of the farm), herd (animal numbers and type), block (land allocation), weather (climate data), and parameters (management) dialog boxes; 2) the run interface which runs the simulation engine, and 3) the output interface. One difficulty for most research-oriented simulation systems is its user interface, which is written to be used by the researcher. This software package addresses this problem by de-coupling the simulation engine from its research-oriented user interface and coupling it with a friendlier rancher-oriented user interface. This method of adding the user-friendly interface should allow research-quality simulation programs to be accessible to the general users.

Technical Abstract: To be able to predict the performance of grazing cattle in extensive rangeland environments, herbage intake is paramount because it quantifies energy intake and performance. Nutrient demand of the animals is the major driver of herbage intake and characteristics of the sward dictate how this demand is met. Estimates of herbage intake and parallel measurements of digestive behaviors of ruminants pose considerable experimental and technical difficulties; as a consequence, advances in the area of research have been slow and costly. Simulation models that integrate over long-time periods will allow for changes in herbage mass or climatic conditions with predicting herbage intake. Dynamic models that include weather, changing forage characteristics, and animal demand are needed to predict long-term beef herd performance and range forage conditions. Vegetation indexes captured from satellite platforms can be used to accurately quantify the dynamics of aboveground net primary production and changes in quality with confidence and has been shown to be consistently sensitive across biomes. The computer software, PCRANCH, is a program for simulating cow-calf herd dynamics over a long-time period. The PCRANCH software consists of three components: 1) the input interface which consists of range (physical characteristics of the farm), herd (animal numbers and type), block (land allocation), weather (climate data), and parameters (management) dialog boxes; 2) the run interface which runs the simulation engine, and 3) the output interface. One difficulty for most research-oriented simulation systems is its user interface, which is written to be used by the researcher. This software package addresses this problem by de-coupling the simulation engine from its research-oriented user interface and coupling it with a friendlier rancher-oriented user interface. This method of adding the user-friendly interface should allow research-quality simulation programs to be accessible to the general users.

Last Modified: 10/1/2014
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