ESTRUS STIMULATION OF ANESTRIC SOWS

Reproduction level is one of the limiting factors in the economy of sl aughter pig production. Reproduction disorders largely consist of post partal anestrus of sows and anestrus of pubertal gilts. The objective of this paper is to evaluate the extent to which the techniques of est rus stimulations of anestric gilts; out-of-estrus sows after piglet we aning and sows found to be not pregnant in the second month after inse mination were successfully applied. The gilts show great variability i n the onset of regular estrus, return to estrus in sows after piglet w eaning is sometimes problematic and the period of seasonal decrease in conception rate in older sows is also critical. To manage these proce sses successfully becomes important anew in relation to the use of bio technological methods of reproduction and embryo transfer. Estrus was induced in exact trials in out-of-estrus pubertal gilts (age of about 8 months, weight around 120 kg), in sows after weaning and sows found to be not pregnant in the second month after insemination. The gilts r eceived Regumate, Hoechst (dose of 0.160 g) or Evertas-P, Lonza Kourim (dose of 0.150 g in 2.5 kg of complete feed mixture) for 15 days in o rder to stabilize the processes on ovaries. They were applied 1 000 i. u. PMSG (Serum Gonadotropin, Bioveta, Ivanovice in Hana) in 24 hours f ollowing the last dose of synchronizing preparation, and 500 i.u. HCG (Praedyn, Leciva Praha) or 500 i.u. PMSG and 300 i.u. HCG in 76 hours in the same regime of treatment (group I or II). Then artificial insem ination with insemination doses of selected sires followed. The out-of -estrus sows 14 to 35 days after piglet weaning at about 35th day afte r parturition and sows found to be not pregnant by a sonographic check (Aloka SSD 500, linear probe 5 MHz) in the course of the second month after insemination (n = 62) were treated by single application of a m ixture of PMSG 500 i.u. and HCG 300 i.u. without blocking sexual funct ions by administration of Regumate or Everts-P (n = 61). A significant ly higher number of gilts with full estrus after stimulation with the higher dose of preparations was observed (group I, 91.7%) than in the gilts applied the lower dose of preparation (group II, 69%, P < 0.05) - Tab. I and an insignificantly higher conception rate in group I gilt s than in group II gilts (79.8%, 69.0%, P > 0.05) were observed in the first part of trials (n = 84, n = 29). There were not any substantial differences in the other indicators investigated (P > 0.05) - Tab. I. Estrus was found in 54 sows after their treatment on average in 7.26 days as for 61 out-of-estrus sows after piglet weaning. Conception rat e in induced estrus was 77% (Tab. II). Natality indicators were at a g ood level. Out of 62 sows found not pregnant in the 2nd month after in semination, forty-five animals (72.6%) returned to estrus 14 days afte r treatment. Seventeen pregnant sows delivered 9.74 piglets on average (Tab. II). The tested method of treatment seems to be promising for b reeders.