It was aimed to verify the effect of the presence of trees and their heights in silvipastoral system on the intake behavior of Nellore heifers in the summer. Ten heifers for the following systems were used: system without shade, silvipastoral system with 8-meter and 18-meter trees. The data were collected in three days during 12 hours, subdivided in morning (7:15 a.m. to 1. p.m.) and afternoon (1:15 p.m. to 7 p.m.). It was evaluated the times and frequency of grazing, rumination, idle and the percentage of time that the animals remained in the shade; black globe-humidity index, whose average and minimum values (86 and 82) were equal for 8-meter tree system and 18-meter tree system; however they were lower when compared to the without shade system (89 and 86). There was an interaction between the systems and the periods for all the analyzed variables, except for the rumination frequency. For system without shade, the grazing time did not differ between morning (202 min) and afternoon (187 min); however the grazing frequency was lower for the afternoon (3.17). For 8-meter trees systems and 18 meter trees system, the grazing time in the afternoon, respectively, with 195.50 and 219.00 min was higher than in the morning, respectively, with 128.00 and 158.50 minutes. The rumination time was higher in the morning for all systems. The grazing frequency for 8-meter trees was 3.58, for the without shade system it was 3.05 and for 18-meter tree system it was 2.22. A higher idle time and the idle frequency was found in system without shade (97.50 min and 3.80 respectively) in the afternoon. For 8-meter tree system (98.50 min and 4.47 respectively) and 18-meter tree system (127.00 min and 4.27 respectively), they were higher in the morning. The animals remained under shade for an average of 43.49% (with trees with 8 m) and 49.81% (with trees with 18 m) of the time. It was concluded that the presence of trees modify the time and the frequency in grazing and idle; however, it does not influence the time and frequency in rumination.
ambience; indle; index; rumination; shade; tree
