Effects of progestagen, PMSG and artificial insemination time on fertility and prolificacy in Corriedale ewes

Reproductive efficiency of Pelibuey and Romanov × Pelibuey ewes synchronized with synthetic progesterone and low doses of PMSG under a hot environment

“…This study shows that the hormonal treatment with progesterone and low PMSG doses may be used to induce and/ or synchronize reproductive activity of hair ewes or their crosses with prolific breeds under high temperatures. It has been suggested that low PMSG doses are not sufficient to stimulate additional follicular development in ewes, consequently reduced response to estrus and longer estrus interval have been observed (Romano et al, 1996). However, results of the present study show an effectiveness of the protocol used to synchronize or induce the estrus activity in hair ewes maintained in heat stress conditions, since 100% of ewes presented estrus signs within the first 48 h after sponge removal.…”

Effect of Selenium Supplementation on Twinning Induction in Barki Ewes

“…Gonadotrotropins are used to induce superovulation in sheep (Evans, 2003). So the injection of PMSG immediately after progestagen sponge removal produce an increase in the ovulation rate (Maxwell et al, 1993 andRomano et al, 1996). Also, Kridli and Al-Khetib (2006) reported that gonadotrotropins improve follicular development, increase ovulation rate and multiple births in ewes.…”

“…However, there are many factors influence the efficiency of PMSG, including the dose and administration time (Timurkan and Yildiz, 2005). It has been found that using of low dose of PMSG is less effective and did not increase fertility or prolificacy (Romano et al, 1996 andAkoz et al, 2006), and the using of high dose of PMSG induced multiple ovulations and improved the fertility and proliferation (Koyuncu et al, 2001 andTimurkan andYildiz, 2005). Meanwhile, as hormonal treatment is still expensive so that the use of high dose tends to elevate the costs for subsistence farmer, therefore the efficiency is difficult to achieve, as the major problem that faces the farmer in sheep reproduction management, is the looking for reproductive techniques, which could help the farmer, and decreases the cost of production.…”

Koyun Ve Keçi̇lerde Üremeni̇n Senkroni̇zasyonu

“…Östrüs senkronizasyonunda kullanılan ekzojen hormonların avantajları olmasına karşın anöstrüste hormon kullanılarak elde edilen gebelik oranları normal üreme mevsimine göre daha düşük çıkmaktadır (3,8,9). Progestagenler Küçük ruminantlarda progestagen uygulamaları, hem üreme sezonunda hem de sezon dışında östrus senkronizasyonu için en sık kullanılan uygulamalardır (4,10 PGF2α temelli senkronizasyon yöntemleri kullanılmamaktadır (1,3,14).…”