A web-based model for simulating whole-farm beef cattle systems

摘要

This paper details the rationale and procedures included in a web-based simulator containing production of beef cattle and cash crops. All biophysical and economical definitions including management in terms of rules constitute user-defined scenarios, which can be saved, retrieved, modified and deleted. Herbage growth may be either provided by the user or estimated from daily climate information. Scenarios are simulated and their outcomes are sent to the user's e-mail as a spreadsheet file, including data and pre-designed graphs to facilitate the interpretation of results. An example simulation study of a grazing-based finishing beef steers with a cycle of 12 months is presented, where new weaners enter the system in the autumn. Increased stocking rates, SR (150, 170, 190 and 210 heads in a 100-ha farm) and different summer maize feeding (SMF) rates were compared (SMF0 = control and SMF1 = intermittent rule-driven maize feeding during summer). In this simulation study, "deviations" from user-defined targets are simplified into two associated rules (a) average farm herbage mass deviation to adjust herbage allowance, and (b) target animal live weight deviation, associated to SMF1. The proportion of unfinished steers at 28th February increased linearly (p <= 0.01) with higher stocking rates and became zero at any stocking rate where the SMF rule was operating (SMF1). The economic response of SR x SMF interaction was significant for gross margin, indicating a positive linear association (p <= 0.05) of SMF1 treatment (rule activated) when SR increases. The potential use of the web simulator as a flexible tool for investigation, training and decision making are discussed