Experimental application of steroids to sows in early gravidity to increase litter size. 2. Effects of repeated administration of progesterone alone or in combination with estradiol benzoate during 2 to 5 consecutive days

: Two mutually adjusted experiments were applied to 607 inseminated gilts and sows on the premises of two farms to test the effects on both pregnancy rate and litter size of repeated treatment, using progesterone in isolation or in combination with 0.5 mg oestradiol benzoate during the phase of implantation. The steroids were applied on the 14th and 16th or 15th and 16th days of pregnancy or between the 13th and 17th or 14th and 18th days following first insemination. The doses per animal and die were 25 mg ofhydroxyprogesterone capronate or 20 mg of progesterone. None of these variants had a secured positive effect upon litter size.