Abstract
Digestion trials were conducted on typical desert ranges in southern Utah to study the effect of intensity of grazing upon the nutritive content of a sheep's diet. Sixteen trials were conducted during the winter grazing season, October 1956, to March 1957. Sheep were grazed on two enclosures of approximately equal size. Four sheep were grazed in one enclosure, and eight in the other, Four sheep in each enclosure were equipped with bags for collection of feces. Forage samples of the parts of the plants being eaten by the sheep were collected daily. Digestibility coefficients and daily consumption were calculated by means of the lignin-ratio technique. Lignin in the diet increased in all trials as intensity of grazing increased. On pure stands, protein, gross energy, ether extract, and phosphorus tended to decrease as intensity of grazing increased. However, on some of the mixtures, a dietary change from one species to another, with increased intensity of utilization, increased the protein, phosphorus, and cellulose content of the diet. In most trials, the digestibility of the nutrients in the diet was considerably reduced by heavy grazing. Forage intake was markedly reduced by heavy grazing in all trials. Copyright © . .