Can GPS monitoring help farmers select the best nutritional management strategy for finishing sheep on pasture?

Abstract

Global Positioning System (GPS) allows monitoring of grazing herds remotely through real-time data collection. We hypothesized that GPS monitoring will establish preferential routes and grazing sites to find the best feeding strategy (supplementation versus no-supplementation) for sheep finished in a Caatinga rangeland (seasonally dry tropical forest) throughout different seasons of the year (rainy period, transition period, and drought period). The experiment was conducted on a 37.9 ha-Caatinga rangeland and comprised 84 days, subdivided into three 28-day periods (rainy, transition, and drought period). Four rumen cannulated sheep were used for estimation of pasture composition during each collection period based on extrusa samples. Twenty-four intact ram lambs (Santa Ines × Dorper F1 crossbred) grazing on Caatinga rangeland were used to test the effects of supplementation on performance, nutrient intake, and nutrient digestibility during the different seasons. The animals were fitted with GPS collars before being released into the Caatinga to monitor their behavioral activity. Greater walking distance, longer grazing time, higher kernel density, and higher walking speed were detected (P < 0.05) for non-supplemented animals, irrespective of season. The supplemented sheep showed greater (P < 0.05) nutrient intake and nutrient digestibility across all experimental periods compared to the non-supplemented animals. Supplemented animals showed greater (P < 0.05) final body weight and average daily gain compared to non-supplemented animals. During the transition and drought periods, supplementation affected all performance variables. In conclusion, GPS is a useful tool to highlight grazing sites according to different seasons and monitor the behavior of F1 Santa Ines × Dorper sheep finished on Caatinga rangeland. Thus, GPS monitoring aids in establishing the best supplementation strategy and consequently reduces productive and environmental losses caused by the spatial distribution of animals and irregular forage use. In addition, supplementation can offset the negative impacts of low forage supply on sheep grazing Caatinga areas.