[The effect of the covering of mares during the postpartum heat on the pregnancy rate]

The present study was carried out to investigate the pregnancy rate after covering in the foal heat (Group I), in the subsequent spontaneous heat (Group II), and in the induced heat (Group III) after administration of 7.5 mg of the prostaglandin F2 alpha analogue Luprostiol (Reprodin, Bayer) between the 20th and 22nd day post partum. Breeding during foal heat resulted in a pregnancy rate of 43.9% compared to 48.6% in the subsequent spontaneous heat post partum. Of 18 mares in group III, 14 mares had a foal heat, whereas 4 others had not shown a foal heat. 1-8 days after treatment, 14 mares (77.8%) returned to an oestrus. In consideration of the mares which had shown a foal heat, oestrus was induced in 85.7% of treated mares. In this group, a pregnancy rate of 50.0% was achieved. In conclusion, the results of the present study indicate that induction of oestrus by treatment with prostaglandin 20-22 days after parturition for covering is a good alternative.

Experimental studies on in vitro maturation of porcine oocytes. I. Effects of medium, energy source and protein source on in vitro maturation rate

Effects of culture medium, energy and protein source on in vitro maturation of cumulus-intact porcine oocytes were examined. The bicarbonate buffered Whittens medium was superior to the PB1 medium buffered with phosphate salts in supporting in vitro maturation. However, modification of energy source of the PB1 medium by reducing Na-pyruvate concentration and adding lactate salts gave also high maturation rate. The supplementation of Whittens medium with 1 g and 3 g BSA/l as a protein source significantly increased incidence of maturation and improved handling of oocytes. There was no significant difference in the ability of low concentration (1 g/l) and high concentration (3 g/l) of BSA in culture medium to support maturation.

Experimental studies on in vitro maturation of porcine oocytes. II. Effects of estradiol-17 beta and progesterone

The simple compounded semi-defined Whitten's medium was supplemented with estradiol-17 beta and progesterone to examine whether they influence the nuclear maturation of porcine cumulus-oocyte complexes. Addition of estradiol-17 beta at concentrations of 1.0 microgram/ml and 10.0 micrograms/ml significantly inhibited the nuclear maturation in comparison to the control group. No significant inhibition of estradiol-17 beta was observed at concentration of 0.1 microgram/ml with respect to the control. After addition of synchronous or subsequent (12 h after the incubation with estradiol-17 beta) supplementation of progesterone at concentration of 1 microgram/ml, maturation rates were as high as control. So progesterone overcame the inhibitory effect of estradiol-17 beta.