Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

Arthur D. Smith


Arthur D. Smith


The range sheep industry, economically important to Utah and to the United States, produces needed food and fiber from much of the less productive land. Improved management will depend on more knowledge of the range ecosystem. Research to determine the time spent by sheep in activities of differing energy demands and to determine what factors affect sheep activity was completed on Utah ranges.

The research was conducted in central Utah on foothill range near Eureka and on mountain range near Scofield. Rambouillet sheep were loosely herded on the sagebrush-aspen areas on mountain range and were unherded on foothill range where they were assigned to 14 pastures. Activities on foothill range were studied in May and June at two grazing intensities on three species of seeded wheatgrasses and on native sagebrush-juniper range. Feeding, standing ruminating, standing idle, lying ruminating, lying idle, and traveling were recorded as all-inclusive activities by observing the behavior of four randomly selected sheep from among marked ewes at 90 instantaneous scans at 10-minute intervals from 0500 to 1950 hours on each of 28 days at each location. Hourly readings were made on the degree of cloudiness, wind movement, ambient temperature, and relative humidity.

Data were analyzed to determine components of variance and to evaluate effects of month, grazing intensity, and kind of forage. Each activity was regressed on environmental factors in a stepwise-deletion multiple regression procedure.

Sheep daily repeated a bimodal routine of early morning feeding followed by midday ruminating and resting which lasted until late afternoon, followed by feeding again before bedding down at nightfall on high ground. On mountain range the morning and afternoon feeding periods were of similar length, but on foothill range the sheep began feeding earlier in the afternoon and thus fed longer in the afternoon than during the morning hours. Sheep were highly synchronous in their choice of activity.

Sheep spent more time feeding on seeded foothill range than on either native foothill or mountain range. Conversely, they spent more time lying ruminating and standing idle during the daylight hours studied on mountain and on native foothill range. Traveling time was greater on mountain than on foothill range, but the horizontal distances traveled were the same at both locations. Sheep spent more time lying idle on native foothill range than on seeded pastures. At the spring foothill location the sheep also spent more time standing idle and traveling in May than in June. No differences were noted in any activities between intensities of grazing.

The daily feeding time of sheep responded positively to average daily temperature. Both lying ruminating and lying idle showed positive regressions on relative humidity. Traveling and standing idle were negatively related to mean daily temperature, which varied only within a narrow temperate range and averaged 20 C during the two periods of study.

Sheep activities necessary to the animal on a daily basis were little affected by small changes in the range environment. Feeding time was proportional to the estimated energy expenditure for maintenance, activity, and production at each location.



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