Process for the alteration of the sex-ratio of mammals

The invention provides an improved method for alteration of the sex ratio in animal (including human) offspring by separation of the population of spermatozoa into fractions which are different by reason of the sex-linked electrical charge resident thereon. The separation is carried out by bringing the spermatozoa into close association with an electrostatic charge-bearing material having a charge the sign of which is opposite to the sign of a chosen portion of the spermatozoa which carries the sex determining character of the unwanted sex, so as to attract and thereby to permit that portion to be isolated, or put to a disadvantage in the fertilization of ova. The invention is concerned with the selection of the charge-bearing material, the adjustment of the pH and particle size thereof, and the control of the surrounding medium in relation to its influence on the charge characteristics of both the charge-bearing material and the spermatozoa.