Pharmacological intervention in swine reproduction

If gilts are known to be cyclic, the options to control estrus are breed-and-abort or feeding allyl trenbolone (Regumate(R)). For breed and abort, terminate pregnancy 25-30 days postbreeding with two injections of prostaglandin F-2 alpha (PGF(2 alpha)), 6-8 hours apart, Gilts should return to estrus within 4-6 days with normal fertility. When feeding allyl trenbolone,you must ensure individual feeding so that gilts receive at least 15 mg (Regumate(R)) per day. There is probably no problem with overdosing, but underdosing (<13 mg per day) may cause cystic follicles. If gilts are known to be prepubertal, gonadotropin (PG600(R)) works well. If inducing estrus with gonadotropin, breed at the induced estrus but expect some possible depression in reproductive performance. If the gilts' cyclic status is unknown, gonadotropin can be used but there may be risks. If gilts are having silent heats, cystic follicles may form and the gifts will become infertile-treat for 14-18 days with allyl trenbolone followed by gonadotropin at withdrawal. Gonadotropin also works well after weaning of the first litter. Injection can be administered on the day of, or the day after, weaning. For farrowing induction, determine gestation length on each farm and do not inject PGF(2 alpha) more than 2 days before due date. Inject a half-dose of PGF(2 alpha) intravulvally at the beginning and end of the day (split-dose). Do not use oxytocin unless at least one pig has been born or continual supervision is practiced.