Feeding behavior of grazing lambs in a silvopastoral system

Abstract Text: Silvopastoral systems may contribute to the reduction of the effects caused by climate change in grazing animals. The aim of this study was to evaluate the presence of trees (Eucalyptus urophylla × Eucalyptus grandis) on the behavior of grazing finishing lambs in Massai grass (Panicum maximum × Panicum infestum). Twenty-four crossbred lambs (27±3.3 kg BW and approximately 90 d old) were blocked by initial BW and assigned into three experimental treatments: TA= unshaded Massai grass pasture; TB= Massai grass pasture with eucalyptus trees spaced 12 × 2m; TC= Massai grass pasture with eucalyptus trees spaced 6 × 2m. Light interception was the criteria for starting grazing period and the residual pasture height was fixed in 20 cm. Animals were observed over 9 consecutive days (3 d of occupation in each of 3 paddocks) in order to assess the grazing activities: feeding (FE), lying ruminating (LR), standing ruminating (SR), lying (LY), standing still (SS), searching for food (SF), and other activities (OT). Three trained observers recorded the behavioral activities, every 10 minutes, for 12 h (from 0700 to 1900 h). Data were submitted to analysis of variance and F test at 5% significance, using the GLM procedure of the statistical package SAS, and the treatments’ means were compared using Tukey test at 5% significance. It were included in the model the treatment, block, day of occupation, day of occupation nested within the treatment, and interactions of treatment × block and treatment × day of occupation. Animals in TA spent more time on FE (TA=59%, TB=53%, TC=50%, P<0.0001), with no differences observed between treatments with trees. Time of LR was greater for TB (TA=25.7%, TB=30%, and TC=23%, P<0.0001), and the interaction was observed between TB and day of occupation (P=0.02), with animals spending more time on this activity at second and third occupational d. On the other hand, animals in TC stayed more time on LY (TA=5.7%, TB=7.7%, and TC=11.8%, P<0.0001), SS (TA=2.5%, TB=3,01%, and TC=4,2%, P=0.0001), and having other activities (TA=0.7%, TB= 0.6%, and TC= 2.9%, P<0.0001), than animals in TA and TB. The activities SR and SF did not differ among treatments (P=0.08 and P=0.14, respectively). Because of the greater availability of shade, the silvopastoral system improved the state of welfare of the lambs, shown by the greatest time spent on ruminating.

Keywords: Eucalyptus, silvopastoral, sheep