Forty years of control of the oestrous cycle in ruminants: progress made, unresolved problems and the potential impact of sperm encapsulation technology

Abstract

Pharmacological control of the oestrous cycle may, with or without sperm encapsulation, remain an indispensable part of any attempt to make artificial insemination available to the ranch-cattle industry. Of the current methods, those most likely to remain acceptable with regulatory agencies and to gain acceptance with industry are those involving the short-term use (7-10 days) of minimal effective doses of progestins (preferably progesterone) and the subsequent use of an analogue of prostaglandin F2 alpha. The use of microencapsulated sperm with a long lifespan would allow artificial insemination to be achieved without reference to the time when heat and ovulation may occur.