Control of Estrus in Gilts with a Progestogen

Abstract

Two trials were conducted to evaluate the effectiveness of a synthetic progestogen, allyl trenbolone, for control of estrus and ovulation in gilts. Estrus was effectively synchronized with 33 of 38 gilts exhibiting estrus 2 to 7 days after last progestogen feeding. There was no effect on fertilization rate in gilts free of ovarian abnormalities. Ovulation rate was higher in gilts fed the progestogen in both Trial 1 (P less than .01) and Trial 2 (P less than .10). Progestogen treatment caused an increase (P less than .01) in the incidence of cystic follicles which resulted in a decrease (P less than .01) in conception rate in Trial 1.

Effects of Breeding at the Second Oestrus or After Post‐Weaning Hormonal Treatment with Altrenogest on Subsequent Reproductive Performance of Primiparous Sows

“…An inadequate interval insemination‐ovulation as a reason to explain the greater return to oestrous rate in Altrenogest‐treated sows can be excluded because at least one insemination was performed within the ideal interval before ovulation (Kemp and Soede 1996) in all groups (except in sows with cysts). Although the presence of cystic follicles reduces the conception rate in Altrenogest‐treated gilts (Davis et al. 1979), ovarian cysts contributed to only 5% (3/56) of the total return to oestrus in Altrenogest‐treated sows.…”

“…2007), 12 days (Koutsotheodoros et al. 1998) or for 18 days (Davis et al. 1979; Martinat‐Botté et al.…”

Pork Production Systems

“…(pregnant mare serum gonadotrophin, PMSG) or PMSG followed 56-72 hours later with human chorionic gonadotrophin (HCG), an ovulating hormone; parenteral gonadotrophin administration to the cycling female of PMSG followed by HCG 96 hours later (dosage level is critical; improper levels result in a high proportion of gilts failing to show estrus; dosages of 1200 IV ofPMSG and 500-1000 IV ofHCG have given good results); oral administration of estrogens followed by progesterone derivatives or of a progestogen, allyl trenbolone (Davis et al 1979), to the cycling female; oral administration of a dithiocarbamoylhydrazine derivative that affects the hypothalamus so as to inhibit ovulation (this drug, sometimes called methallibure or ICI 33828, has received widespread attention as a means of controlling estrus without problems with cystic ovarian follicles, but it produces teratogenic effects when ingested during pregnancy, so probably will not find commercial use); injection of 10 mg of prostaglandin F2a(PGF2a) on days 13 and 14 after inducing accessory corpora lutea with PMSG-HCG administration in cycling sows (since PGF a is not luteolytic in the pig until day 12 of the estrous cycle, it does not offer a practical means of synchronizing estrus when used alone, according to Hansel and Convey 1983). As more is learned about the physiological effects of prostaglandins, further refinement can be expected in ovulation control methods.…”

Testing the Altresyn Product for Oestrus Synchronization in Gilts

“…Animals were separated and individually treated. It should be mentioned that it was given the right dose for each animal, because underdosing may lead to cystic follicles (Davis et al, 1979;Kraeling et al, 1981).…”