Zinc as a possible causal factor in the sterilizing sperm tail defect, the 'Dag-defect', in Jersey bulls.

The zinc content was determined in semen samples from four young Danish Jersey bulls showing the typical 'Dag defect' (greater than 50% strongly coiled or bent sperm tails). Two of the bulls were half brothers. Semen samples from 14 normal fertile Jersey bulls served as controls. The normal material showed a zinc content in the centrifuged sperm of 190 +/- 15.8 mug/g d.w. and in the seminal plasma 81 +/- 31.2 mug/g d.w. In the four abnormal bulls the following elevated values were found: in the centrifuged sperm 310 +/- 109.5 mug/g d.w. and in the seminal plasma 137 +/- 75.2 mug/g d.w. (see figs. 1 and 2). One of the Dag defect's main localizations, the outer dense tail fibers, has a very high zinc content and this fact together with the heredity of the defect make further studies most promising.