THE EFFECT OF PMSG DOSE ON EMBRYO NUMBER AND QUALITY IN SOWS AND GILTS

Superovulation in donors is an important factor influencing embryo rec overy. Numerous authors agree on the fact that combined applications o f PSMG, HCG or LHRH preparations are the best superovulation treatment of sows. A trial was conducted on three groups of sows-donors and one group of gilts. Sows received a diet with Regumate (Hoechst) for 18 d ays (group 1) or for 17 days (groups 2 and 3). After Regumate feeding had terminated, the donors were administered i.m. PMSG (Serum gonadotr opin, Bioveta, Ivanovice in Hana) at doses of 1 500 i.u. (group 1, n = 4), 2 000 i.u. (group 2, n = 10) and 2 500 i.u. (group 3, n = 9) in 2 4 hours while they received a dose of 500 i.u. HCG (Praedyn, Leciva Pr aha) in another 72 hours. Two to four inseminations with fresh semen w ere executed on the next two days (the first in 24 hours after HCG app lication, and then in 12-hour intervals until estrus termination - unt il disappearance of standing reflex). Surgical interventions were made to recover embryos on the fourth day after the 1st insemination. Uter ine horns (about 30 cm) and oviducts were flushed in a descendent orde r using a Foley catheter. The flushing was taken into a 100ml NTS bott le and stored at a temperature of about 25 degrees C. Embryos were iso lated and subjected to morphological evaluation under a stereomicrosco pe, followed by cultivation in a complex conditioned medium H-MEMD or M 199 with 20% of fetal calf serum until further use. A total of 15.5 transferable embryos were recovered from four donors (91.2% out of the recovered ones); 14.2 transferable embryos (82.5% out of the recovere d ones) were obtained from 10 donors of group 2; nine donors of group 3 produced 12.8 transferable embryos (39.3% out of the recovered ones) , which is significantly less than in the two preceding groups (P < 0. 01). The trial also included 70 clinically healthy nulliparous gilts o f the Czech Expressly Meat breed at the age of about 8 months and weig ht 120-130 kg. These donors received the preparation Evertas-P Lonza K ourim at a dose of 0.150 g per 2.5 kg feed mash per head/day for 15 da ys. Twenty-four hours following the last application of Evertas-P the donors received an i.m. application of 1 000 i.u. of PMSG (Serum gonad otropin, Bioveta, Ivanovice in Hana). An i.m. application of HCG (Prae dyn, Leciva Praha) followed in 76 hours. To make the date of inseminat ion and ovulation more accurate the donors were administered i.m. the preparation LHRH in the speciality Supergestran at a dose of 1 mi (i.e . 25 mu g lecirellin) in 92 hours after PMSG. The gilts were inseminat ed with homosperm insemination doses when the standing reflex was reve aled, reinsemination took place in 12 to 18 hours after the first inse mination. Embryos were recovered post mortem on day 5 after the first insemination by flushing the prepared uterine horns and using Krebs-Ri nger phosphate at a dose of ca. 40 mi per horn. Positive reactions of ovaries to the stimulating procedure were observed in 64 gilts (91.4%) with the total average production of 17.66 +/- 9.28 CL, i.e. 16.1 CL per treated donor. Total post mortem recovery on average amounted to 1 2.64 +/- 7.88 embryos (71.6%), out of them 9.08 +/- 8.83 were transfer able embryos (71.9% out of the recovered ones). The number of unfertil ized oocytes and degenerated embryos was approximately the same (1.67 +/- 2.40 and/or 1.89 +/- 3.20; 13.2 and/or 14.9%). The effect of estru s signs and intensity on stimulation and embryo recovery was examined in 33 donors. The animals with expressive signs of estrus produced alm ost a twofold number of recovered and transferable embryos (10.5 and 8 .0 versus 5.2 and 4.7, Tab. III).