[Biotechnical increase of litter size in early pregnant sows using steroid application. 1. The effect of a single application of hydroxyprogesterone capronate on fertility response in ovulation-synchronized gilts and old sows].

: One single intramuscular injection of hydropyrogesteroncapronate was given in an experiment to 199 gilts and 239 old sows on the 13th or 15th or 17th day after insemination to test various fertility performance parameters. Doses were 50 mg, 75 mg or 100 mg. Positive effects on litter size were established from the majority of nine compared experimental variants. The number of live-born piglets was increased up to two. Several groups of gilts had higher mean litter weights. More studies are necessary to prepare an adequate therapeutic regime by which to reduce loss of embryos in swine.