A study investigating the effect of sheep stocking
density and grazing duration on forage intake, grazing
efficiency, dietary selectivity and subsequent forage
accumulation in tall fescue(Festuca arundinacea)-
subclover(Trifolium subtaranium) pastures was conducted
near Corvallis, Oregon during early and late spring in
1988 and 1989. Grazing treatments were 2, 6, and 10-day
duration and corresponding stocking densities 380, 130, 78
and 1390, 460 and 280 ewes/ha during early and late trials
each year, respectively.
Average daily intake and grazing efficiency were
highest (P< 0.05) in the 10-day duration and lowest in the
2-day duration. During the first 2 days of all duration
treatments, average daily intake decreased as stocking
density increased (P< 0.05). Manure cover and crowding
stress may explain lower average daily intake under the
shorter duration/high density treatments. However,
stocking density had little effect on grazing efficiency.
This was largely due to the high amount of forage
destroyed under the low density treatments which offset
the effect of higher forage intake of that treatment.
Within the 10-day duration treatment, average daily
intake was the same over time (P> 0.05), while grazing
efficiency decreased as grazing progressed (P< 0.05). The
low grazing efficiency during the early stages of grazing
reflected high initial forage destruction probably caused
by the movement of animals at the start of grazing to
establish bedding and habitual use areas.
Growth rate of forage after grazing was highest in
the longer duration paddocks and lowest in the shorter
duration paddocks (P< 0.05), but the yield was similar
under all treatments (P> 0.05).
Although short duration/high density grazing is
considered to be non-selective, sheep were equally or more
selective under very short duration/very high density
compared to longer duration/lower density treatments in
this study. The 2 days duration was not an attractive
management option since the intake and grazing efficiency
were low, and the animals were selective. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36815 |
| Date | 19 June 1992 |
| Creators | Ali, Eltom E. |
| Contributors | Sharrow, Steven H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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