The performanceof lambs for the mating in the autumn in improved native pasture fertilizedwith 250 kg/ha of mineral formula 5-20-20 was evaluated. Two levels of nitrogen(N) (100 and 200 kg/ha of N as urea) divided in two applications, 70% and 30%,in February, 3, and March, 17, 2005, respectively, were tested in a completeblock design with two replications. Plots without N application were used ascontrol. Evaluation was done on continuous variable stocking in order to maintain16% of forage allowance (16 kg DM/100 kg live weight [LW]). Grazingperiod extended from January, 21 to May, 31. Studied variables were: stockingrate, DM disappearance, in % of LW, average daily gain, body score condition,weight gain per area and, pregnancy rate. The DM disappearance did not differbetween treatments and periods of evaluation, presenting limited values in relationto the probable potential intake. The stocking rate showed positive effect ofthe level of N and did not differ along the evaluations. The other studied variables(body score condition, average daily gain and weight gain per area) presentedsignificant variations between evaluation periods due to influence of the waterdeficit that occurred during the experimental period. The pregnancy rate didnot show significant effect of the level of N. Despite the water deficit whichoccurred during the experimental period and compromised the performance of thepasture variables and, by consequence, animal response to nitrogen fertilization,the native pasture improvement by fertilization is capable to support high stockingrates.
