Sheep Performance and Behavior in Silvopasture Systems.

Silvopasture systems integrate trees with forages for grazing ruminants. Reports of forage and animal productivity from these systems have been variable. In some cases, animal gains are similar or better despite lower forage yield. During three summer grazing studies, we compared black walnut and honeylocust-based silvopasture systems with open pastures in a randomized complete block design (r=3). Pastures were rotationally stocked with four to seven lambs depending on forage availability. All lambs were weighed and fecal samples from a subset of the lambs were taken every four weeks. Body temperatures and grazing behavior measures were recorded within a replicate within a week, and these measures were taken sequentially within each of three experimental periods. Ewe lambs (n=3) within each experimental unit were equipped with a vaginal temperature sensor (3 days) and a wideband audio recording device (1 day) for detecting prehension events. Weather stations within each experimental unit were used to calculate the Wet Bulb Globe Temperature (WBGT) index and time lapse cameras documented sheep behavior every 60 seconds. Forage availability measurements taken with a rising plate meter indicated no difference between the honeylocust silvopasture (4900±100 kg/ha) and the open pasture (4900±100 kg/ha; P=0.9916), though forage availability in the black walnut silvopastures (3500±100 kg/ha) was lower than that within the other treatments (P<0.0001). Lamb gains in the honeylocust silvopastures (12.6±1.0 kg/period) were greater than the gains of the open pastures (9.4±1.0 kg/period; P = 0.0254) and the gains of the black walnut silvopastures (8.5±1.0 kg/period; P = 0.0046). No difference was found between the latter two systems (P = 0.5173). Lambs without access to shade spent more time standing up than lambs in the black walnut silvopastures (P=0.0006) and lambs in the honeylocust silvopastures (P=0.0007). Preliminary results indicate that grazing time may be higher for the lambs in the silvopastures.