THE UTILITY OF CONTROLLED-RELEASE NORGESTOMET IMPLANTS IN SYNCHRONIZING ESTRUS AND DIAGNOSING PREGNANCY IN EWES, AND FACTORS AFFECTING THE DIFFUSION RATE OF NORGESTOMET FROM SILICONE IMPLANTS

One hundred Suffolk and cross-bred ewes were implanted with norgestome t/silicone implants to assess efficacy and utility, and to determine f actors affecting norgestomet diffusion. The overall estrus and lambing responses were 90% and 67%, respectively. Administration of the impla nt for 14 days during pregnancy, in conjunction with progesterone dete rmination on the 14th day, permitted the diagnosis of pregnancy status with 100% accuracy. Norgestomet implantation had no adverse effects o n established pregnancy. implants that were movable in situ on the 14t h day had less connective tissue encapsulation and a higher (p < 0.05) norgestomet diffusion rate than implants that had rigid subcutaneous placement and more connective tissue encapsulation.