Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Animal Husbandry

Major Professor

Charles S. Hobbs

Committee Members

Sam L. Hansard, Harold J. Smith


The fluorine problem in livestock feeding is one of increasing importance. Fluorosis has been commonly defined as “chronic poisoning with fluorine” (American Illustrated Medical Dictionary). To some, the word may mean the condition that results when the abnormal ingestion of fluorine is sufficient to harm the animal (i.e., as the term is defined medically). To others, the word may mean the condition resulting from any ingestion of fluorine above normal levels.

Fluorosis in livestock has been encountered in several ways, one of which is the use of mineral supplements containing fluorine. These minerals are the different varieties of phosphate rock which contain 3 to 4 percent fluorine, and phosphatic limestones which contain fluorine in proportion to the amount of phosphorus present. In the manufacture of superphosphate from phosphate rock, approximately one-fourth to two-thirds of the fluorine is driven off by volatilization as hydrogen fluoride or as silicon tetrafluoride, as reported by Mitchell and Edman (1951).

Chronic fluorosis in farm animals has been reported from many countries in areas adjacent to industrial plants emitting fluorine-containing gasses and dusts. The production of acid phosphate and defluorinated phosphate, the electrolytic production of aluminum, the manufacture of bricks from fluorine-bearing clays, the calcimining of ironstone, and certain enameling processes have been chiefly involved. However, even the fumes from coal-burning furnaces may contribute to the industrial hazard, since coal and shales associated with coal contain from forty to several hundred parts per million fluorine, according to Churchill et al. (1948). Since fluorine is very active chemically and does not occur in a free state, the fluorine-bearing fumes from factories processing fluorine-containing ores may be largely hydrofluoric acid, ad the fluorine-bearing dusts may consist of fluorides, such as sodium fluoride or cryolite, which have been volatilized and then condensed in the cooler surrounding air. The leaves of plants may absorb the gas and collect some of the dust on their surfaces, according to Mitchell and Edman (1952). The extent of contamination of the forage, therefore, will depend on several factors, such as the amount of the fluorine-containing materials being emitted, weather conditions, prevailing winds, topography of surrounding terrain, and type of vegetation.

Files over 3MB may be slow to open. For best results, right-click and select "save as..."