Efficiency of different hormonal treatments for estrus synchronization in tropical Santa Inês sheep

Abstract

The aim of this study was to evaluate the effect of (i) the duration of hormone treatment with progestogen sponges during the seasonal anestrus and (ii) the administration of two doses of prostaglandin at 7 days apart during the breeding season on reproductive parameters of Santa Inês ewes. In experiment 1, 32 ewes received intravaginal MAP sponges for 6 (G6 days), 9 (G9 days), or 12 (G12days) days and 75 μg D-cloprostenol i.m. and 300 IU eCG i.m. 1 day before sponge removal. In experiment 2, 23 ewes received two doses of 0.48-mg sodium cloprostenol i.m. 7 days apart. Ovarian follicular dynamic was assessed through transrectal ultrasonography. Blood samples were collected daily to determine progesterone concentrations. In experiment 1, estrus and ovulation rates did not differ (P > 0.05) among protocols and between cyclic and acyclic ewes at the beginning of the experiment. The G9 days treatment showed a lower dispersion of ovulations in relation to onset of estrus when compared to G6 days and G12 days. In experiment 2, all ewes exhibit estrus and ovulated after the second dose of prostaglandin, although ewes that were in diestrus at D0 showed subluteal concentrations of progesterone during the follicle development stage of the treatment. In conclusion, the use of progestogen device during 9 days promotes lower dispersion of ovulation when compared to its use for 6 or 12 days, and the protocol of two doses of prostaglandin 7 days apart synchronizes estrus efficiently but results in follicular development under low progesterone concentrations.

Application of hormonal subdoses at the Bai Hui acupoint for estrus synchronization in sheep

“…All animals that presented estrus also achieved ovulation, with an average rate of 93.33%. Ovulation occurred at 73.7±5.9 h after sponge removal, which was similar to the previously reported intervals [70.4 h by Teixeira et al (2016) and 80.4 h by Moreira, Brasil, Silva and Ramos (2014)] in Santa Inês sheep. Ovulation duration is another important parameter.…”

Effects of flushing with rehydrated corn grain silage on follicular development in tropical Santa Inês ewes

“…The length of estrus observed was similar to that reported by Ascari et al (2013) and Teixeira et al (2016) in Santa Inês sheep after estrus synchronization with progestagens. The greater variability observed may be related to the presence of animals with single or multiple ovulations (double or triple).…”

Combined treatment with oestradiol benzoate, d‐cloprostenol and oxytocin permits cervical dilation and nonsurgical embryo recovery in ewes

“…Santa Inês sheep have a relatively low ovulation rate (1–1.3 ovulation per oestrous‐induced ewe; Cavalcanti, Brandão, Nogueira, & Fonseca, ; Teixeira et al., ; Venturi et al., ) and lamb productivity (1.3 lambs born per ewe; Mexia et al., ). Overall, the average egg/embryo recovery rate of 41.2% (7/17) obtained in this study appeared to be low.…”

“…> 0.05. *Protocols: 37.5 μg of d-cloprostenol (latero-vulvar) and 1 mg of EB (intramuscular or intravaginal) were given 16 hr and 50 IU of oxytocin (intravenous) 20 min before transcervical embryo recovery Fonseca, 2012;Teixeira et al, 2016;Venturi et al, 2016). and lamb productivity (1.3 lambs born per ewe;Mexia et al, 2004).…”