Diets of Cattle in North Central South Dakota

This study was conducted over a two year period during the summer months on the Grand River National Grasslands near Lemmon South Dakota on a 2,510 ha pasture to determine cattle diets. Cattle feces were collected monthly near each of 8 permanent water tanks located throughout the pasture. Microhistological analysis of cattle feces was used to identify and quantify diets by plant species. Eight common plant species comprised the greatest portion of the diet. Grasses and grass-like plants accounted for 84 percent to 99 percent of the diets with sedges common in spring (79%) and early summer (53%). Key forage species were, sedges (Carex spp), blue grama (Bouteloua gracilis), needle and thread (Hesperostipa comata) and green needlegrass (Nassella viridula) that comprised 82 percent of the diet. These plants are key forage species for monitoring seasonal grazing on the grasslands. Forbs ranged from less than 1 percent to 14 percent. Shrubs were a minor component of the diet making up less than 1 percent. Similarity indices changed throughout the season and ranged from 0 to 99 percent, indicating that some plants were highly selected or avoided by cattle (low similarities) and other plant species were consumed in the same proportions as available on the grassland. Rank order correlation indicated seasonal selectivity with an overall correlation of 0.75