Red deer and cattle diet composition in La Pampa, Argentina

Presence of 2 large herbivores in the same rangeland makes assessment of proper stocking rates and management practices rather complex. This study evaluated composition and overlap of red deer and cattle diets in a semiarid, temperate rangeland of La Pampa province, Argentina. Deer and cattle diets were estimated by microhistological analysis of feces. Fifteen samples were collected for cattle and deer during fail, winter, spring, and summer of 1994/95 (Period 1) and the same seasons of 1996/97 (Period 2). Red deer and cattle diets were different (P < 0.01) within each sampling season. Diets were also different (P < 0.01) among sampling seasons within each animal species. Red deer were better shrub users than cattle. Deer consumed more than 4 times the amount of shrubs than cattle during all seasons. Shrubs accounted for 28 to 50% of deer diets in most seasons, and from 6 to 12% in cattle diets. Forbs were a variable component of diets. However, red deer harvested more forbs than cattle in most sampling seasons (P < 0.05). Cattle were better grass users than red deer. Cows consumed more (P < 0.05) perennial graminoids in all seasons, and based their diet on cool-season perennial grasses. A trend for red deer to behave as an intermediate feeder, compared with cattle could be suggested. In the environment of our study, deer and cattle diet overlap varied greatly depending on availability of palatable fractions of forbs, shrubs, and grasses. Forb and shrub regrowth would reduce the diet overlap.