干旱区生态环境知识资源中心

Grazing distribution can be improved by using adapted cattle breeds that travel to distant areas of extensive pastures. A 2-yr study was conducted to evaluate grazing distribution and diet quality of Angus, Brangus, and Brahman cows (seven cows per breed group) in the Chihuahuan Desert during three seasons (winter, early summer, and late summer) using three pastures. Two GPS collars were randomly assigned to each breed group and cow positions were logged every 10 min for 10- to 14-d periods in each pasture (3 periods.season(-1)). In 2008, breed groups were evaluated in separate pastures and data were analyzed as a 3 x 3 Latin square design. In 2009, all breed groups were evaluated at the same time in the same pastures. Fecal samples were collected in 2008 and analyzed using near infrared spectroscopy (NIRS) to estimate diet quality. If positions recorded when cows were resting were excluded, Brahman cows traveled greater distances per day than Angus cows throughout the study and greater (P <= 0.10) than Brangus cows in all but one season during 2009. No differences in average distance to water were detected (P > 0.10) among breed groups. During early summer in 2008 and early and late summer in 2009, Angus cows maintained a more linear grazing path (P <= 0.10) than Brangus or Brahman cows. Brahman cows displayed more sinuous grazing paths (P <= 0.10) than other breeds during early and late summer seasons in 2009. In 2008, no differences in crude protein content of diets were detected (P > 0.10) among breed groups during all seasons. Spatial movement patterns of Brahman cows appeared to differ from Angus and Brangus cows; however, there was no evidence to suggest that there was any advantage in use of areas far from water by any breed group.