Effects of Fluorine on Dairy Cattle. IV. Milk Production

Abstract

Summary Thirty-two Holstein females were maintained from three to four months of age until 7.5 yr of age on diets containing four levels of fluorine, two levels of concentrate, and two levels of a calcium-phosphorus mineral. Statistically, only the concentrate level treatment affected milk production and then only in the first lactation. Combined lactation, histological, pathological, and other data, however, indicate a reduced milk production on 109 ppm F treatment in the third and fourth lactation and possibly in the second. The 55 ppm treatment appeared to adversely affect milk production in the fourth lactation. Cows on the higher concentrate treatment tended toward higher milk production than did those on the lower level. Mineral treatment did not affect lactation when missing values were not calculated. Efficiency of lactation was not affected by F intake, although higher concentrate and 1% mineral treatments induced more efficient production than the lower concentrate and 3% mineral treatments. All milk residues of F were within safe levels for consumption, although residues increased with increased dietary F. Based on this study, the tolerance of F for lactation in dairy cows over a 7.5-yr period is less than 55 ppm on a dry hay basis or less than 49 ppm on a total dry diet basis.