PSXIII-8 Grazing Behavior of Cows Grazing Natural Grassland Under Silvopastoral Systems or Full sun

Abstract

Abstract The objective of this study was to evaluate the grazing behavior of mature beef cows grazing natural grassland in silvopastoral systems (SPS) in comparison with pasture systems in full sun (FS) during the austral summer in South America. A total of fifty-five Braford crossbred multiparous suckled cows (352 ± 43 kg) were randomly assigned to two treatments, with two replicates, in a complete randomized design: SPS (n=28) and FS (n=27). Global positioning system (GPS) devices were placed in six randomly selected cows per treatment (three per replicate) to track geolocation every five minutes during five consecutive days. Data were analyzed using the Java program GRAZEACT to determine total distance traveled (km), area explored (ha), and animal activities (h/d). Type of animal activity was defined by GRAZEACT based on movement velocity, being categorized as: resting (velocities< 3 m/min), grazing (3< velocities< 25 m/min), and traveling (velocities >25 m/min). Each of these variables were automatically calculated for four time periods: Night Pre-Dawn hours (00:00-06:00 h), Daytime hours (06:00-20:00 h), Night Post-Sunset hours (20:00-24:00 h), and 24 h. There was a treatment effect for distance traveled, explored area, grazing and resting in the 24 h period (P ≤ 0.0154). Specifically, cows grazing SPS had a greater distance traveled (P = 0.044) and area explored (P < 0.0001) during the daytime hours compared to cows grazing FS. In accordance to this, for the same period, SPS cows had lesser resting time (P < 0.0001) and spent an extra 1.5 h grazing (P < 0.0001) compared with their FS counterparts. In conclusion, SPS changed spatial and temporal grazing behavior. The provision of shade by SPS allowed a greater grazing activity through the daytime hours, period associated with greater temperatures during summer, most-likely by improving thermal comfort of animals.