The Effects of Short or Long Term FGA Treatment with or without eCG on Reproductive Performance of Ewes Bred Out-of-season

Abstract

Abstract:The objective was to evaluate the effects of intravaginal FGA sponges inserted for 4 or 12 days with or without eCG on reproductive performance of ewes out-of-season. Forty-eight anestrous ewes were assigned in equal numbers to four treatments in a 2x2 factorial design. Ewes were administered with FGA sponges on May 17 for 12 days (12-day-FGA-eCG and 12-day-FGA groups, n= 12 each) and on May 25 for 4 days (4-day-FGA-eCG and 4-day-FGA groups, n= 12 each). All treatments were timed to end together on May 29 (day 0, 0 h) at which time sponges were withdrawn and eCG or saline was injected. Five fertile rams which had been isolated from ewes were joined at 0 h for breeding and estrus detection. Blood samples were collected to compare progesterone (P 4 ) concentrations and for pregnancy diagnosis. Overall estrus expression occurred in 40/48 ewes which differed only between 12-day-FGA-eCG and 4-day-FGA (p<0.05) groups. Intervals from 0 h to onset of estrus were shorter (p<0.05) in 12-day-FGA-eCG than those in 12-day-FGA and 4-day-FGA groups with no differences between 12-day-FGA-eCG and 4-day-FGA-eCG or between 12-day-FGA and 4-day-FGA groups. Progesterone levels were basal from day -12 through day 4 (p>0.1) and increased gradually thereafter until day 15. Progesterone remained elevated through day 19 in 11/12, 8/12, 9/12 and 6/12 ewes, respectively, which were diagnosed pregnant on day 30 by ultrasonography. Of the 34 ewes that became pregnant, 31 lambed 150 days following day 0. Pregnancy loss occurred only in 3 ewes from the two groups that did not have eCG treatment No differences in pregnancy and lambing rates and the number of lambs born were found between 12-day-FGA-eCG and 4-day-FGA eCG. The overall pregnancy and lambing rates obtained from mating at first service were 70.8 and 64.6%, respectively. In conclusion, the 4-day-FGA and eCG regimen could adequately replace the 12-day-FGA out-of-season. Application of such a 4-day-FGA protocol must be accompanied by eCG treatment upon sponge removal.

The effects of short-mid-long term intravaginal sponge application on reproductive performance of karacabey Merino ewes in the anestrous season

“…The lambing rate in the differently treated ewes was 61.5, 88.5 and 92.3%, respectively. The results of the present study are compatible with the study results of Santos et al (2010) who demonstrated that short-term progestagen treatment does not improve the fertility of ewes, as was previously reported (Husein et al, 2007;Ustuner et al, 2007;Amer and Hazzaa, 2009). In the present study, the multiple birth rate and litter size in the treatment groups were lower than the values observed in hormone treated native ewes of Turkey (Askin, 1988;Koyuncu and Yerlikaya, 2007;Karaca et al, 2009).…”

Fertility rate of short-term progestagen pretreated ewes in relation to breed: A field study

“…Based on physiology of exposure to progestagens compared to long-term exposure. Our results are in accordance with others, where short treatments combined with natural mating resulted in higher (Viñoles et al, 1999) or equal (Ungerfeld and Rubianes, 1999;Ataman et al, 2006;Housein et al, 2007) pregnancy rate, during the breeding or anoestrous season, respectively, compared to long treatment. Recently, Martemucci and D'Alessandro (2011), shown that FGA-PGF2α-eCG short-term (5-days) treatments could be used as a valid alternative to FGA-eCG long-term protocol for synchronization of oestrus after natural mating during the breeding season.…”

Ovarian response of Suffolk ewes to estrous synchronization using short-term protocol

“…In the end, however, a subluteal effect may happen and decrease the speed of follicular renewal (Hamra et al, 1986). The use of progestagen during a short time would be an alternative solution because it could improve estrus synchronization in ewes (Husein et al, 2007).…”