Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor
Default forage species are artefacts of management and climate and may not be those initially planted or designed for current use. Some producers believe that default pastures are less risky in beef backgrounding operations than species bred for rotational grazing or novel annual mixtures because they have no establishment costs. Pastures consisting of default (80% quackgrass-smooth bromegrass: 20% Kentucky bluegrass) and improved species, perennial, meadow bromegrass-alfalfa, or annual, winter triticale – oat mixtures, were compared for beef production within summer and sequential summer-stockpiled systems over five years at Lacombe, AB, Canada. All pastures received broadcast applications of 100 kg/ha fertilizer-N and annual pastures were sown each spring. Crossbred beef heifers (328 +/- 3 kg initial wt.) were rotationally grazed within replicated paddocks using the Put and Take method. Gross margins per head and per ha were calculated at the end of the summer and summer-stockpiled systems for the three pasture types. Continuous probability functions were fitted to the observed gross margin data using the normal distribution. A
Monte Carlo procedure was used to smooth the distributions with 10,000 iterations using the Excel add-on at Risk. The gross margin distributions for pastures were then ranked according to stochastic dominance within the summer and summer-stockpiled systems. For the summer system, distributions of the default and improved species overlapped to the extent that they were considered equally risky, but both dominated the annual pasture gross margin distribution. The probability for a loss or negative gross margin was 30% for improved and default pastures and 83% for annual. For the summer-stockpiled system the improved pastures dominated the other pasture types, but the default pasture dominated the annual pasture; probabilities of a loss were 14%, close to 0.0% and 40% for default, improved and annual pastures, respectively.