Impact of beef cattle on eucalyptus trees in a silvopastoral system

Abstract

Eucalyptus species are widely adopted in silvopastoral systems in Brazil due to their adaptive potential to different climates and soils. However, damages caused by cattle to trees may compromise the system’s success. The aim of this study was to determine the impact of beef cattle on Eucalyptus grandis clone GPC 23 trees during the grazing period in an integrated crop-livestock with trees (CLT) system of Avena strigosa + Lolium multiflorum. The effect of two N levels (50 x 150 kg/ha) on animal and forage production were also evaluated, with the integrated crop-livestock system (CL) serving as control. The experimental design was randomized blocks of treatments arranged in a 2×2 factorial scheme (2 systems x 2 N levels), with three replicates. In winter 2022, forage production and animal performance, assessed as average daily gain (ADG) and live weight gain (LW) per area per day (Gha/day), were evaluated during 139 days of grazing. Total forage production, ADG, and Gha/day were higher in CL (7972 ± 775.7 kg DM/ha, 0.799 ± 0.0392 kg/animal/day and 4.27 ± 0.259 kg LW/ha/day, respectively) than in (6478 ± 350.9 kg DM/ha, 0.638 ± 0.0546 kg/animal/day and 2.91 ± 0.259 kg LW/ha/day), even at similar sward heights (between 22 and 24 cm). The animals damaged the bark of the trees, even after the trees had reached a diameter at breast height of 9.9 cm. The damage was classified as high intensity in 91.1% of the trees, affecting their quality as sawn wood. Preventive measures must be adopted regarding the use of E. grandis in a silvopastoral system with cool-season grasses.