Date of Award:

5-1955

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Range Management

Committee Chair(s)

Arthur D. Smith

Committee

Arthur D. Smith

Committee

Laurence A. Stoddart

Committee

C. Wayne Cook

Committee

Lorin E. Harris

Committee

David O. Williamson

Abstract

The conflicting problems involving the herds of mule deer (Odocoileus hemionus) are of major interest throughout Utah. Individuals who are affected the most are sportsmen, ranchers, fruitgrowers, sanitation engineers, home owners, federal administrators, and big game managers. Mainly, the problems arise as a result of insufficient forage, especially on the winter range. Here, factors such as increased deer numbers, decreased range productivity, severe winters, and expanded agricultural activity make more acute the problem of a naturally critical season.

Restoration of forage by artificial measures may be necessary as a management solution for certain areas. Range rehabilitation, rather than winter feeding during critical periods, has much in its favor, for it can lead to a proper balance between deer numbers and a sustained forage supply. By contrast, feeding leads to further unbalance.

If plants are to be established on the ranges as a source of deer food, more qualitative and quantitative information as to their nutritional value should be had by the game manager.

Studies of forage preference and chemical composition of plant parts have been the most popular means in the past by which to obtain knowledge of deer-forage relationships. Few investigators have resorted to digestion trials for measurements of nutritive quality and daily consumption of forages consumed by deer.

Certain advantages favor the digestion trial over other approaches used by animal nutritionists in determining forage nutrient values. Nevertheless, criticism still prevails owing to the methods of partitioning forage into chemical fractions. All known digestion trials with deer to date have used the method of proximate chemical analysis called the Weende method, whereby the forage is partitioned into protein, ether extract, ash, crude fiber, and nitrogen-free extract, with the latter two constituents containing the carbohydrate fraction. A refinement in technique which may prove useful in deer nutrition is to partition the carbohydrate fraction of ingested forage and feces into lignin, cellulose, and "other carbohydrates". The technique is called the modified method of proximate analysis.

The lignin fraction of the modified analysis is regarded as indigestible. By the Weende method crude fiber is considered as the portion resistant to digestion; an assumption which is often unjustified, since crude fiber may be digested as much as or more than nitrogen-free extract. Digestion coefficients for lignin as determined from livestock studies indicate no digestibility of this complex organic substance which is present in all forage. However, owing to the anatomical differences in domestic ruminants and deer, it is possible that digestion of lignin may take place in the latter.

Lignin has recently been used as a "tracer" material for determining the digestibility and consumption of forage. The technique is based on the assumption that if lignin is completely indigestible a ratio may be made between lignin and any other constituent in the feed and feces from which the digestibility of the constituent under consideration may be calculated. The lignin-ratio technique is widely used in livestock nutrition research and has advantages over conventional digestion trials, the main advantage being that animals need not be confined to crates. Rather, they are free to graze in a more natural manner, and hence, the results secured may more closely approximate actual digestion.

It was the purpose of this investigation to find out if lignin present in species providing winter forage for deer is digested to any degree by them.

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