Date of Award:

5-1987

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

Philip J. Urness

Committee

Philip J. Urness

Committee

Brien E. Norton

Committee

Frederick D. Provenza

Committee

Paul F. McCawley

Committee

William F. Campbell

Abstract

Rangelands in Jordan are deteriorated due to a combination of harsh environmental conditions and human misuse. Jordan is importing increasingly large quantities of meat and animal products to meet the demand from its growing population. Sheep are supplementarily fed during the dry season and large quantities of grain supplements are imported every year.

Significant success has been attained in the establishment of Atriplex nummularia Lindl. (ATNU) in Jordan. There is, however, a general lack of adequate research to determine if ATNU is effectively utilized by local sheep, to what extent it is utilized and to what extent it tolerates grazing. The objectives of this research were to determine the effects of grazing ATNU at two intensities (moderate and heavy) on subsequent production of ATNU browse, and on sheep live weight.

Results of this research showed that HNU shrubs are grazing tolerant, they are stimulated by grazing to produce more forage than the non-grazed shrubs. When heavily grazed in the fall, they showed greater compensatory growth than moderately grazed shrubs, but the moderately grazed shrubs gave sustained production better than those heavily grazed in both good and bad years.

Sheep grazing ATNU shrubs with native forage (grasses and forbs) in the fall gained more weight at the moderately grazed treatments. The amount of sheep-live-weight gain was positively affected by the amount of food intake per sheep metabolic body weight and inversely affected by the percentage of ATNU browse in the diet. ATNU although less preferred by sheep than grasses and forbs, could probably be used up to 40% of the diet and still maintain sheep live weight.

ATNU is a good source of forage especially during the dry season, it provides (with native grasses and forbs) a high-quality forage and may considerably reduce the amount of costly supplements imported to Jordan.

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