The hydrogen-ion concentration of the semen of the bull

1. The mean pH of 221 ejaculates of clinically normal bulls was 6·73 ± 0·020. Significant differences were noted between different bulls.2. There were highly significant negative correlations between the pH. of the ejaculates and the concentration of spermatozoa, the volume of ejaculate and the motility of the spermatozoa.3. The more acid the semen was on collection, the better was the motility retained on storage. Semen which retained its motility well became increasingly acid during storage. A change in the pH in the alkaline direction during storage had an adverse effect on motility. The more acid the pH on collection the less likely was a decrease in acidity during storage.