This study evaluated the microclimate in a system without shade (WS) and in a silvopastoral system (SP) with eucalyptus during summer and winter, by measuring the air temperature (Ta), black globe temperature (Tg), relative humidity (RH), wind speed (Ws), every 2 hours for 24 hours between rows, shade (SP) and no shade effect (WS). It was employed the randomized blocks design (months), in the plots (systems), subplots (hours) and sub-subplots (seasons). Except for Ta and RH, the Tg ( 24.73, 26.41ºC), Ws (3.16, 4.57 m s -1 ), Black globe-humidity index (BGHI) (71.83, 73.84), Thermal load index (TLI) (74.53, 76.11) and Radiant thermal load (RTL) (526.46, 595.80 W m -2 ), respectively for SP and WS, were higher in WS. Ta, RH and Ws had a quadratic effect of hour. There was an effect of season, respectively in summer and winter, on the Ta (27.55, 14.93°C), RH (72.11, 60.68%), Tg (29.80, 21.33°C), BGHI (80.04, 65.63), TLI (81.64, 69.00) and RTL (575.65, ). Tg, RH and RTL showed an interaction of season x hour, and a quadratic effect, and the RTL had an interaction of system x season. The Tg was correlated with BGHI (0.962), TLI (0.956) and RTL (0.809). The silvopastoral system decreased the Tg and Ws, and made the environment more harmonious by decreasing the climatic differences between seasons.

The aim of this work was to verify if the presence of trees and its height in formed silvipastoral systems with eucalyptus planted in rank can modify the microclimate and improve the environment for bovine raising during the day in summer. It was evaluated the microclimate of the environment in formed silvipastoral systems in rank of eucalyptus with 8 m, 18 m and 28 meters of height, compared to a system no shade in the summer. The experimental design was a split plot with six hour time in sub parcels. The systems are made up of parcels and the months as block in four replications and the interaction hour × system. The air temperature, black globe temperature, relative humidity and wind speed were observed to create the following indexes for thermal comfort: temperature-humidity index; black globe-humidity index; heat load index and the radiant thermal load. Excepted for the relative humidity, there was interaction for time × system for all variables and indexes. Interaction occurred for: air temperature at 10 a.m. and 6 p.m.; wind speed from 8 a.m. to 4 p.m.; temperature humidity index at 10 a.m. and 12 p.m.; black globe temperature, black globe humidity index, heat load index, and radiant thermal load at all the hours. During the summer, the system with shade of 28 m trees had the lowest average of black globe temperature; wind speed; black globe humidity index; radiant thermal load index; and heat load index. There was a reduction of wind speed average in systems 8 m, 18 m and 28 m trees in, respectively, 20.7; 50.0 and 48.0% in relation to no shade system; however it was not proportional to the height, with influence of the rank porosity and pantries height. Nevertheless, for radiant thermal load index the reduction was proportional to the height of the trees with 10.24; 12.49 and 20.76%, respectively, for 8 m, 18 m and 28 meters of height. There was a reduction of the thermal stress in the environment due to the presence of trees, being the heat load index thermal the index that better demonstrated the effect, despite of not being proportional to the rank height.

-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.

ABSTRACT. It was evaluated the intake behavior of Nellore steers in system without shade (WS), and silvopastoral system (SP) maintained in star grass (Cynodon plectostachyus) in summer and winter. Twentyfour Nellore steers were used (12 in each system), mean age 18 months and weight of 294.5 kg. The design was completely randomized with two seasons, two treatments, 24 hours and 12 repetitions. The observations were conducted in three days, for 24 hours, with an interval of 15 minutes, with effect of the hour on the grazing behavior (GRAZ) with a maximum of 52.1% and lying ruminating (LYRUM) with a minimum of 12.3%, both at 14h. The lying idle (LYIDL) was influenced by hour with a minimum of 11,6%at 14h, and by season, with 23.9% in summer, and 13.9%, in winter. However, the standing ruminating (STRUM), without effect of hour, was affected by the interaction of season x system in summer (9.43%) and (6.19%), and winter (4.36%) and (8.27%), respectively, for SP and WS. Standing idle (OCEMP) was influenced by hour, with maximum 15.8% at 14h, and an interaction of system x season, in summer (20.10%) and (8.82%); and winter (9.05%) and (8.44%), respectively, for SP and WS. The SP system has changed the environment that affected the animal intake behavior.Keywords: welfare, season, Nelore, shadow.Comportamento de bovinos de corte e o microclima em sistema com e sem sombra RESUMO. Avaliou-se o comportamento ingestivo de novilhos anelorados, em sistema sem sombra (SS), e em sistema silvipastoril (SP) mantidos em grama estrela (Cynodon plectostachyus) no verão e inverno. Foram utilizados 24 novilhos anelorados (12 em cada sistema), com média de 18 meses e peso de 294,5 kg. O delineamento foi inteiramente casualizado com duas estações, dois tratamentos, 24h e 12 repetições. As observações foram realizadas em três dias, durante 24h, com intervalo de 15 min., com efeito da hora para os comportamentos pastando (PAST) com máxima de 52,1% e ruminando deitado (RUDEIT) com mínima de 12,3%, ambos às 14h. O ócio deitado (OCDEIT) foi influenciado pela hora e estação, em que nas horas com mínima de 11,6% às 14h enquanto no verão (23,9%) e inverno (13,9%). Ruminando em pé (RUEMP), sem efeito da hora, porém sofreu interação estação x sistema, no verão (9,43%) e (6,19%); e inverno (4,36%) e (8,27%), respectivamente, para SP e SS. O ócio em pé (OCEMP) sofreu efeito da hora, com máxima de 15,8% às 14h, e interação estação x sistema, no verão (20,10%) e (8,82%); e inverno (9,05%) e (8,44%), respectivamente, para SP e SS. O sistema SP alterou o ambiente afetando o comportamento ingestivo animal.Palavras-chave: bem-estar, estação do ano, Nelore, sombra.

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