Abstract:
The objective of this thesis is to assess four winter feeding
programs of spring-calving brood cows that may improve profitability
to ranching operations of the Harney Basin, Oregon. The four feeding
strategies include strip grazed rake-bunched hay, supplemented range
grazing, strip grazed meadow pasture, and baled hay feeding. These
first three alternatives were compared to baled hay feeding, the
preferred practice of the region, in terms of profitability to the
operation and management requirements.
To evaluate the alternatives a deterministic biophysical-economic
simulation model was constructed. The biophysical model
simulates relationships between (1) the physiological status and
nutritional requirements of mature gestating cows, (2) the forage
base being utilized, and (3) the effects of the physical environment
upon the nutritional requirements of cows and their ability to forage
successfully for food. The biological simulation is designed to
provide, as output, measures of cow reproductive performance and forage utilization. This information is integrated into herd and
pasture management subroutines to yield measures of herd production,
and pasture and feed utilization. An economic subroutine uses
results from the herd production and forage utilization subroutines
to estimate costs and net returns to each feeding strategy.
Risk is introduced into the simulation by varying the climatic
components of the physical environment. Four winter scenarios are
represented, ranging from mild to very severe. Probabilities are
assigned to each winter scenario for each feeding program. The
probabilities under each alternative for each of the four climate
scenarios are combined to yield estimates of the expected net return
of the feeding strategy.
Analysis of the results indicate that raked-bunched hay is the
best alternative to baled hay feeding. Returns are substantially
higher as a result of reduced wintering costs. Cow performance
factors remain nearly identical to hay fed cows, and management of
the winter operation is simplified. In addition, there appears to be
little risk associated with management of the raked hay alternative.
The range grazing program also yields superior economic results
to the operation when compared to baled hay feeding. Although there
is considerable variation in net returns to the alternative over the
climate scenarios, the expected return to range grazing is
substantially higher than the baled hay strategy. Variability in net
returns to range grazing is due to effects of ground snow depth
levels which may prevent cows from feeding on range forages. When
these conditions occur emergency hay feeding is required. Management of the operation is intensified, increasing with the severity of the
winter.
Based upon the economic results of the simulation it appears
that range grazing is a promising alternative to baled hay. However,
because empirical data are limited regarding the adaptability of this
alternative in the Harney Basin, more information is needed regarding
(1) ground snow depth level effects upon the feeding success of cows,
and (2) reproductive performance of cows following severe winters.
The results of the meadow grazing alternative indicate that
this strategy is not a viable alternative to baled hay feeding.
Returns to the operation are reduced as the result of poor cow
reproductive factors, and the vulnerability of this strategy to
relatively shallow snow cover requiring large amounts of emergency
feeding.
