Produtividade de um modelo de produçao para novilhas de corte primíparas aos dois, três e quatro anos de idade

The objective of this work was to evaluate, by means of simulations, the performance of primiparous beef heifers at the two ("one year" system), three ("two years" system) and four years ("traditional" system) of age. In the "one year" system, the model supplied differentiated feeding in the first winter, for a 100 days, after weaning, which was constituted by one of the three alternatives: a) continuous grazing in a cultivated pasture of rye grass; b) continuous grazing in a natural pasture and supplementation with diet; and c) feedlot, with sorghum silage + urea. After the 100 days, the heifers grazed together improved natural pastures. The models used to compare the systems were constructed on Excel spreadsheet, starting from an original model. The referring biological data of "one year" system were collected at Agropecuaria Guatambu,.Dom Pedrito, RS, in 395 beef calves. The percentage of cows in each system, in November, in the beginning of the mating period, corresponded to 44,28 36,35 percent and 33,86 percent, for the "one year", "two year" and "traditional" systems of beef production, respectively. The "one year", in relation to the other systems, was superior for live weight production/ha, outcome rate and stock efficiency. The choice for one of these systems will depend certainly on the particular conditions of each property and of the behavior of the producer in relation to the risk. (RA)