Masters Theses

Date of Award

8-1961

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Husbandry

Major Professor

O. Glen Hall

Committee Members

Charles S. Hobbs, Marvin C. Bell

Abstract

The primary functions of phosphorus in animal metabolism, structure and reproduction are as follows: (1) it is concerned in the maintenance of a proper reaction in the blood; (2) with calcium it is of great importance in the formation of bone and teeth; (3) it is necessary for the maintenance of a normal calcium concentration in the blood; (4) it plays an important role in carbohydrate metabolism and the transfer of energy in cellular activity.

The requirements of phosphorus for cattle and sheep have long been estimated based upon the needs of the animal body. Bone development, blood phosphorus levels and animal performance have been the principal indicators of phosphorus adequacy in much of the work done for establishing the phosphorus level in the diet that is needed for optimum animal production. More recently rumen bacteria are also being employed for this purpose.

Cellulose is the main constituent of the crude fiber in roughages. Herbivores in general and ruminants in particular digest and use large amounts of cellulose with the help of the rumen bacteria. A number of workers have studied the factors affecting rumen microorganisms and cellulose digestion in vivo and in vitro. Vigorous rumen microbial activity which is essential for proper and efficient feed utilization by cattle and sheep depends upon the presence and availability of various nutrients in the rations fed. Experiments have shown that rumen bacteria require a source of nitrogen, readily available energy, minerals, fatty acids and other factors. It is now known that phosphorus is one of the essential minerals required by these bacteria. The amount of phosphorus required for optimum bacterial activity in the rumen may be an important criterion for fixing the need of the animal, for this mineral.

The use of phosphatic supplements which are available today in rather large numbers for livestock feeding assumes importance in this context. The chemical content of phosphorus in them may often be misleading when an attempt is made to compute the feed requirements of farm animals. Not all the phosphorus in these phosphatic compounds may be available to the animal. Therefore several phosphatic compounds presently available as feed supplements for livestock were obtained to evaluate their availability. The artificial rumen technique was employed for the first part of the experiment for its obvious advantages. The assay is based on the fact that phosphorus depleted rumen microorganisms will rapidly digest cellulose only when supplied with an adequate amount of available phosphorus.

The following study was undertaken therefore:

(1) To determine the effect of phosphorus from each of three commercial supplements of dicalcium phosphate and defluorinated phosphate upon cellulose digestion by rumen microorganisms in vitro.

(2) To determine the effect of one good and one poor commercial defluorinated phosphate supplement as revealed by item (1) above, on digestibility of a semi purified phosphorus-poor basal ration by sheep.

(3) To compare the relative availability of the two samples of phosphorus used in (2) above to sheep.

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