| Abstract: | During 1 965 and 1966 a critical study was made of the quality, condition, and performance of some 1000 dairy cows on 45 farms in four compass areas in the region centering on Arvida, Quebec, where an Aluminum Smelting operation emits effluent that results in a contamination of their forage of from about 10 to as high at times of 1 05 ppm fluoride. Cattle winter forage in this area is consistently poor in quality, partly because of the species that can be grown, but more importantly because of adverse spring climatic conditions which in many years prevent harvest of hay until the plants have fully matured and ripened. Its effective feeding value, measured by recorded voluntary consumption and in vivo digestibility, has been found to be about half that of high quality legume hay. Commercially prepared meal mixtures constitute the non-roughage portion of the winter rations fed, and these by analysis have been found individually to contain from 65 to 85 ppm fluoride contributed chiefly, and probably exclusively, by some form of rock phosphate included as a source of the necessary phosphorus supplement. The factors statistically examined in the study included: growthiness, size, fleshing, and milk production of the milking cows; the incidence and degree of dental fluorosis, and skeleton accumulaton of fluoride (by tail bone biopsy of 48 representative cows); the makeup and amounts of ration fed daily during the winter farm feeding; and the feeding and breeding management followed. The statistical procedures of variance and covariance, and of correlation and partial regression were computer analyzed. The results indicated that inadequacy of energy intake traceable largely to the nutritional nature of the hay fed was of significantly greater importance than any of the other factors recorded. Fluorine ingestion carried a statistical weight of only about 3% as a cause of the performance of the cattle. By difference it appeared that breeding and the generally unsatisfactory management of the cows, especially the feeding practice, was about twice as important as feed allowances as causes of the poor quality and performance of the cows. (The terms fluorine and fluoride and the symbol F are used interchangeably in this paper. Levels of fluorine are reported on the elemental basis.) |
