Abstract
The mineral status of breeding beef cows from three livestock stations in Tottori, Okayama and Kagawa Prefectures was investigated by evaluating mineral concentrations in diets and blood plasma of cattle. The Na concentrations in diets with the exception of October pasture grass from Tottori and December pasture grass from Okayama were lower than the requirement (0.08%). The P concentrations in the pasture grasses from three stations were as high as the requirement (0.22%) or lower than the requirement. The Ca concentrations in all diets were higher than the requirement (0.28%) with the exception of the supplemented hay from Kagawa showing 0.20%. The Mg concentrations in all diets were higher than the requirement (0.10%). The ratio of K/(Mg+Ca) in July and September pasture grasses from Okayama and April pasture grass and supplemented hay from Kagawa were higher than 2.2. The Cu concentrations in diets were regarded as marginal level ranging from 5.67 to 10.65ppm and the Zn concentrations in diets ranged from 24.9 to 80.2ppm in the three stations. The cows which showed lower plasma inorganic phosphorus (Pi) concentrations than the critical level (4.5mg/dl) were observed each month in all the three stations. The cows which showed plasma Ca concentrations below the critical level (8.0mg/dl) were observed each month in Okayama and in December in Kagawa. One third of the cows from Okayama and a half of the cows from Kagawa showed lower plasma Mg concentrations than the critical level (1.8mg/dl). A half of the cows from Okayama showed lower plasma Cu concentrations than the critical level (0.65μg ml). No cows showed plasma Zn concentrations below the critical level (0.8μg/ml) in any of the three stations. The low plasma Pi and Mg concentrations of cows were most likely due to the low P concentration and the high ratio of K/(Mg+Ca) in diets respectively. In Okayama, material antagonistic to Cu metabolism was suspected to exist in the diet. The relation of Ca concentrations between diets and plasma in Okayama was not clear.
