Simulation of beef cattle production systems in the Llanos of Colombia: Part 2—Results of the modelling

Verifications and validations were conducted of a simulation model of beef cattle production on tropical ranges of the Colombian Llanos. Liveweight changes were simulated for individual cows sampled at random, for cow herds alternately grazing native savanna and molasses grass (Melinis minutiflora) and for steers grazing native savanna. Correlation coefficients between observed and simulated liveweight change were high. Simulations of the calving rates of cow herds from two experiments at Carimagua Research Station were also conducted and there was reasonably good agreement between observed and simulated data. Shortcomings of the model included an inability to simulate the heavy weight losses of grazing animals on molasses grass during the dry season and under-estimates of calving rates for the most productive herds. An experiment was conducted with the validated model from which it was concluded that grazing molasses grass and weaning of calves at 84 days of age would do little to increase calving rate.