Abstract
Blood plasma minerals and their effects towards the fertility in 136 cows randomly selected from 26 dairy farms in central Thailand were studied. An average of 8.60 mg% Ca, 5.97 mg% P, 2.45 mg% Mg, $85.9{\mu}g%$ Cu, and $160.9{\mu}g%$ Zn in plasma was observed. Compared to the critical deficient values, 24.3, 10.3, 11.8, 28.7 and 0.0% of the surveyed cows obtained the respective elements in plasma below the standard levels. No significant difference (p >.05) in plasma concentrations of Ca, P, Mg and Zn for the low fertile (conception rate > 3) and fertile (conception rate < 3) cows was found. However, plasma Cu of the low fertile cows (averaged $77.2{\mu}g%$) was lower (p <.01) than that of the fertile ones (averaged $91.12{\mu}g%$). Additionally, it is observed that 47.1% of the cows with the low fertility problem obtained plasma Cu below the 65.0 pg% critical deficient value.