Selective Grazing by Sheep as Shown by a Comparison of the Chemical Composition of Range and Pasture Forage Obtained by Hand Clipping and that Collected by Esophageal-Fistulated Sheep

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Abstract
Selective grazing by sheep was studied by comparing the chemical composition of forage samples obtained by hand-clipping and by esophageal-fistulated sheep on a wide variety of range and pasture conditions at various seasons of the year. The sheep consistently selected forage higher in protein and lower in crude fiber than that obtained by hand-clipping. No consistent differences in lignin or ether extract content were obtained. The silica-free ash content of the forage collected by the fistulated sheep tended to be higher than that of the hand-clipped forage. At least part of this difference must be attributed to the ash content of the saliva. Pooling all data for ungrazed forage indicated that fistulated sheep selected forage containing 4.1% (±0.55) more protein and 3.5% (±0.29) less crude fiber than found in hand-clipped forage. When the forage had previously been grazed by a large flock of sheep the differences were somewhat smaller—3.0% (±1.1) for protein and 0.90% (±0.44) for crude fiber. The difference for crude fiber between grazed and ungrazed forage was highly significant. Correlation and regression studies indicated it was not feasible to estimate what a sheep would eat from hand-clipped material. Copyright © . .