Abstract
Cattle grazing in abandoned fields has recently been of great importance in promoting effective utilization of local resources in Japan. The objectives of this study were to investigate spatial distributions of grazing cattle in abandoned fields and to analyze relationships between the patterns of spatial distribution and energy expenditure (EE) of the grazing cattle using global positioning system (GPS) and geographic information system (GIS). GPS collars were attached to 2 Japanese Black cows and their positional records with an interval of 5 minutes were collected during 3 seasons throughout 2008; June, September, and October. Using GIS, a 3D map of the study area was derived from a digitized contour map and the slope gradient of each pixel was calculated. Utilization distributions of grazing cattle were estimated by fixed kernel method using GPS records. Three levels of intensity utilization areas (high, middle and low) were estimated from the utilization distributions and thereby their sizes and average slope gradients (ASG) were calculated. EEs of grazing cattle were estimated from walking speeds and walking slope gradients calculated from GPS records. Results showed that ASGs of high and middle intensity utilization areas in October were significantly steeper (P<0.05) than those in June. Sizes of all the intensity utilization areas in daytime (from sunrise to sunset) were significantly larger (P<0.01) than those in nighttime (from sunset to sunrise following morning). ASGs of all the intensity utilization areas in daytime were significantly gentler (P<0.01) than those in nighttime. ASGs of all the intensity utilization areas in both daytime and nighttime were positively correlated with EEs in June. Although sizes of high and middle intensity utilization areas exhibited negative correlations with EE in September, they were positively correlated with EE in October.
