Heifer performance and body temperatures in open pasture versus silvopasture in mid-Atlantic USA

Heat stress is of growing concern for producers and costs the livestock industry > $2B annually, with predictions that this cost will increase with climate change. Silvopasture is a potential strategy for reducing heat stress in livestock and improving productivity. In this study, we compared heifer performance and body temperatures in open pasture (OP), newly established loblolly pine (Pinus taeda) silvopasture, thinned pine silvopasture (PSP), and thinned hardwood silvopasture (HSP). Heifers were weighed at 4-week intervals, and their intravaginal and external hide temperatures were recorded using small temperature loggers and a drone with a thermal camera, respectively. Pre- and post-grazing forage biomass was greater in OP compared to silvopasture treatments in both years (p < 0.05). Type of grazing system had no effect on the seasonal weight gains of the heifers (P = 0.5764). Heifers in HSP and PSP had cooler intravaginal and hide temperatures (p < 0.05) during the afternoon hours (1150–1830 h) compared to heifers in OP, indicating reduced radiant energy loads and improved welfare during summer. Heifers without shade had a larger increase in hide temperature from morning to afternoon than heifers with access to shade (10.7 vs. 3.9 °C). These findings suggest that silvopasture systems can reduce heat stress while maintaining similar levels of livestock productivity. However, animal performance in silvopastures by month was variable. Management strategies that increase forage production in silvopastures may further the value of these systems in terms of greater land-use efficiency relative to open pasture systems.