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CONTEXT Climate change presents challenges for livestock productivity and animal health. Thus, management strategies to mitigate the effects of the global temperature increase on livestock production have become progressively relevant. However, the use of integrated crop-livestock-forestry systems to optimize the beef cattle thermal balance has not been examined more deeply. The study aimed to evaluate the microclimate in a non-shaded pasture system (NS) and in an integrated crop-livestock-forestry system (ICLF) and its influence on thermoregulatory and endocrine responses of zebu and composite bulls, during different climatic seasons. The experiment was carried out in a tropical region, São Carlos-SP, Brazil (21°57′42″S, 47°50′28″W). Nelore (Bos indicus) and Canchim (5/8 Bos taurus x 3/8 Bos indicus) bulls were equally allocated in a non-shaded system (NS; n = 32) or in an integrated crop-livestock-forestry system (ICLF; n = 32). The animals were monthly evaluated and the data were analyzed using a GLM Model. Means were compared using Tukey test (P < 0.05). The ICLF system reduced the air temperature (−0.6 °C; P = 0.0010), the Black Globe Temperature and Humidity Index-BGHI (−3.8; P < 0.0001), and the Radiant Thermal Load (−104 W/m2; P < 0.0001) compared to the NS system. The infrared thermograms of NS bulls were characterized by higher temperatures on the surface of the back and in the trunk, during Autumn and Winter (P < 0.05). In addition, NS bulls presented higher respiratory rate (RR: 35.85 ± 0.88 vs 31.97 ± 0.88 breaths/min; P = 0.0210) and internal body temperature (BT: 39.54 ± 0.05 vs 39.35 ± 0.05 °C; P = 0.0057) during Autumn. There was a significant reduction in cortisol concentration (−12.13 ng/mL; P < 0.05) in both systems throughout the experiment. Nelore bulls had lower RR and BT, lower mean concentration of cortisol, and higher secretion of triiodothyronine than Canchim bulls. The ICLF system was effective in mitigating the microclimate of pastures due to the action of natural shading, providing greater thermal comfort, especially for composite animals, and favored the maintenance of homeothermy in the bulls. This thesis has provided a deeper insight into the physiological mechanisms involved in the thermoregulation of cattle raised in integrated crop-livestock-forestry systems. The insights gained from this study may be of assistance to indicate ICLF as a suitable option for increasing animal welfare in tropical climates. [Display omitted] • Afforested systems have been singled out as a possible solution for mitigating animal thermal stress. • We assessed the thermoregulation of beef bulls over 13 months. • The air temperature, the BGHI, and the thermal load were lower in the crop-livestock-forestry system. • Bulls in the crop-livestock-forestry system showed greater thermal comfort and lower heat stress biomarkers. • The Crop-livestock-forestry system may be a suitable option for increasing animal welfare in tropical climates. [ABSTRACT FROM AUTHOR]

Understanding how the bioclimatic factors influence the animals homeothermy and behavior is essential to implement good practices for tropical livestock. Thus, the objective of this work was to study the effect of the incorporation of the arboreal component in pasture production systems in a tropical environment on thermal comfort and to analyze the influence of the integrated crop-livestock-forestry system on the behavior of beef cattle. The study was carried out in São Carlos-SP, Brazil, region of tropical altitude subtype, for 13 months. Sixty-four Nelore (Bos indicus) and Canchim (5/8 Bos taurus x 3/8 Bos indicus) non-castrated males (26 months; 358 kg LW) were allocated to production systems with pastures in full sun (Group FS; n = 32) or with forested pastures (Group ICLF; n = 32). The microclimate of the pastures was permanently monitored by weather stations. The behavior of the animals was assessed through an observational method in monthly campaigns and a continuous electronic monitoring method based on the use of an accelerometer and acoustic sensor coupled to collars. Higher means of the black globe temperature index were registered in the morning and the afternoon, with a very challenging condition for the animals during the spring and summers, especially for the Group FS. The observational results showed that animals in the Group FS grazed longer in the morning than animals in the Group ICL, mainly in the warmer seasons (P < 0.05). The animals in FS remained lying down longer than the animals kept in the ICLF system, during rumination or resting (P < 0.05). The animals in the Group ICLF preferred the use of shaded areas within the forested system and their frequency of visits to the drinking fountain was reduced in the morning (−55 %) and afternoon (−26 %) shifts. Electronic monitoring showed that animals, regardless of the production system, spent 38.4 % of their time resting, 32.6 % in displacement, and 29.0 % in rumination. The animals in FS had a higher displacement time at night and dawn, and less time resting at night (22:00 h and 23:00 h) and dawn (2:00 h to 6:00 h), which affected their circadian rhythm and restricted the time devoted to restorative effects of rest. Therefore, the use of the arboreal component proved to be beneficial for obtaining a more favorable microclimate for raising cattle on pasture, being useful for increasing animal thermal comfort and for the expression of behavioral attitudes favorable to the maintenance of homeothermy in a tropical environment. • Thermal comfort and behavior in afforested (ICLF) or non-forested (FS) pastures were studied. • Observational and electronic methods were used to describe beef cattle behavior. • ICLF allowed maximize the use of shaded areas for grazing, ruminating, or resting. • Animals on ICLF reduced the search for the drinking fountain and mineral mixture. • ICLF benefited microclimate and increased the thermal comfort. [ABSTRACT FROM AUTHOR]