Estimating net energy for activity for grazing beef cattle by integrating GPS tracking data, in pasture weighing technology, and animal nutrition models

Logan VandermarkJameson R Brennan^*Krista EhlertHector Menendez

• South Dakota State University, Brookings, United States

Beef cattle production is largely dependent upon rangelands for cattle to convert unusable plantbased fiber into an animal-based protein source for human consumption. Solutions are needed to meet both the growing demand for animal-based protein and the desire for managers to produce energetically efficient cattle. Animal energetics has largely focused on beef cattle within confined systems such as feedlots. Beef cattle grazing extensive rangelands likely have a higher energetic requirement due to the need to forage across heterogenous landscapes. For this study, we created a precision systems model to account for net energy for activity of beef cattle on extensive rangeland systems by integrating in-pasture weighing technology, GPS data, and animal nutrition models. Results from the mixed model ANOVA for net energy for maintenance activity (Nemr_act) indicate a significant main effect of treatment (P < 0.0001) and stocking rate (P < 0.0001) but no significant interaction (P = 0.705). These results indicate that though the overall energetic expenditure may be similar, individual pasture effects may impact the proportional cost of physical activity partitioned between Resting, Flat, and Ascending energetic expenditure as animals utilize diverse landscapes. Cattle grazing extensive rangelands within the intermountain west with greater variations in both topography and slope will likely impact energetics to a greater extent. As the rate of precision technology and virtual fencing is adopted, applications of the algorithm developed in this study may be used to quantify these differences at larger landscape scales across western rangelands.