CONTROLLED DELIVERY OF TESTOSTERONE PROPIONATE SUPPRESSES FERTILITY IN TREATED FEMALES AND INDUCES PRENATAL ANDROGENIZATION IN FEMALE OFFSPRING WITHOUT PHENOTYPIC MASCULINIZATION

Four experiments were conducted on the controlled delivery of testosterone propionate in cattle and sheep. Blood testosterone concentrations were more consistent across time when silicone implants were used for delivery than when compressed pellets were used for delivery. Heifers with high testosterone concentrations were infertile. Female offspring born to heifers exposed to a consistent delivery of testosterone propionate, beginning before and continuing throughout gestation, had normal female phenotype. Prenatally androgenized females were at least as fertile as untreated heifers. Combined, the four experiments demonstrate that 1) testosterone suppresses fertility of treated females, and 2) phenotypic masculinization and sterility of female offspring can be avoided when androgens are delivered prenatally by controlled release implants regardless of stage of gestation when treated.