Administration of hCG on the seventh day after initiation of estrus may circumvent negative effects of cervical relaxation protocol in sheep: Preliminary results.
Cervical relaxation with association of estradiol benzoate, cloprostenol and oxytocin allows a cervical transposition and embryo collection in sheep by the non-surgical method (Fonseca et al., Theriogenology, 86: 144-151, 2016). However, in recipients, the use of this protocol becomes impracticable due to the use of cloprostenol, which is a luteolytic agent. Sheep are known to form accessory luteal bodies after hCG administration seven days after the onset of estrus (Castro et al., Anim. Reprod., 12: 148, 2015). Therefore, the objective of this study was to develop a cervical relaxation protocol in embryo recipient ewes without compromising future gestation. The data were presented in a descriptive way. Thirteen ewes were observed in estrus out of 24 females submitted to the synchronization protocol. The pregnancy rate were 75.0% (3/4) in G1, 0.0% in G2 (0/5) and 50.0% in G3 (2/4). Preliminary results suggest that the association of estradiol benzoate and oxytocin may compromise the onset of pregnancy and that the use of hCG at the end of the protocol in D7 can circumvent partially these negative effects, allowing the establishment of pregnancy
