|Abstract or Summary
- This study was conducted to delineate the cause or causes of
winter deaths in deer and to provide information from which emergency
feed could be formulated. Deer were shot at monthly intervals through
the winter in Wallowa County, Oregon. Samples from the rumen, liver,
mandible, blood and feces were taken to study mineral consumption,
tissue levels, storage and excretion. Deer collected the next winter
from another area of the county were also sampled for comparative
purposes. Deer from two other areas in the state were also sampled
and along with the Wallowa County samples, were used to establish
standards for deer tissue levels of various minerals.
The minerals studied were P, Ca, Mg, Na, Fe, Cu, Mn, S, K,
and Co. Mineral supplies, except Mg, were felt to be adequate. The
diets of the Wallowa County deer appeared to be marginal in Mg,
especially since winter requirements for Mg are apparently higher
than for other seasons. Marginal levels of dietary Mg would be
expected to gradually deplete body stores and cause a lowering of
blood Mg. A cold environment will lower levels of Mg and so will starvation.
If all three of these occurred at once, it was theorized that a
"winter tetany" could occur and result in large scale deaths.
Emergency feeding of deer in the past has not been successful
and areas of supplemental feeding usually have higher mortality rates
than non-supplemented areas. Another trial was conducted to study the
effect of prolonged weight loss, followed by starvation, on the acceptance
and reactions of animals offered emergency feeds ad lib. Twelve
goats were fed chopped orchard grass hay for 43 days, during which
time they lost weight. At the end of this time period, they were starved
for five days. After starvation they were offered the following feeds
ad lib. : barley pellets, alfalfa pellets, 45:55 concentrate to hay ratio
pellets, and chopped alfalfa hay or chopped orchard grass hay. The
goats seemed able to adapt to the rations without problems as measured
by feed intake, rumen pH, rumen lactic acid levels, body temperature
and fecal dry matter. They ate only sparingly at first and then gradually
increased intake up to full feed over a five day period.
Blood Mg levels in the goats showed a decline with starvation.
The body seemed unable to compensate for this decline by increasing
absorption from the intestinal tract or controlling excretion as fecal
levels remained similar throughout starvation. The blood levels did
not return to normal when the goats were first realimented. It appeared that the goats went into a negative water balance when they
were starved, because urine volume increased and water intake decreased.
When an estimate of metabolic water was derived, however,
the water balance seemed even.