40 YEARS OF CONTROL OF THE ESTROUS-CYCLE IN RUMINANTS - PROGRESS MADE, UNRESOLVED PROBLEMS AND THE POTENTIAL IMPACT OF SPERM ENCAPSULATION TECHNOLOGY

Pharmacological control of the oestrous cycle may, with or without spe rm 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 regulato ry agencies and to gain acceptance with industry are those involving t he short-term use (7-10 days) of minimal effective doses of progestins (preferably progesterone) and the subsequent use of an analogue of pr ostaglandin F-2 alpha. The use of microencapsulated sperm with a long lifespan would allow artificial insemination to be achieved without re ference to the time when heat and ovulation may occur.