Managing embryonic and calves losses after twin pregnancies induced by transfer of in vitro-produced Nellore embryos.

Two farms applying reproductive technology for the Nellore beef cattle were selected. Both farms had the same technology programme of oestrous synchronization and embryo transfer, but management was different, especially regarding twins pregnancies. In the present study, we followed the farms from the moment of oestrous synchronization, embryo transfer (two per cow), until delivery and first care of the calves. In farm A, cows presenting twin pregnancies (5 from 13) were submitted to delivery induction, as well as calves and cows were monitored after birth. In farm B, such management was not followed with the twin pregnant cows (31 from 49). In both farms, freemartinism was detected, but this was not a problem as none of the animals would be selected for breeding. No dystocia was observed in farm A, while 48% of the twin pregnancies in farm B ended up in dystocia. Furthermore, the mortality rate of new-born calves in farm A was 10%, while in farm B it reached 32%. Although twin pregnancies remain a concern, we showed here that proper management during and after delivery minimizes animal and economic losses.

Cryosurvival after exposure of IVF-derived Nellore embryos to different cryoprotectants and exposure times during vitrification.

We evaluated the effects of the vitrification solution (i.e., ethylene glycol (EG) + dimethyl sulfoxide (DMSO) with or without propylene glycol (PG)) and of exposure time on the re-expansion and hatching rates of vitrified Bos indicus embryos. In vitro produced embryos (n = 1050) were divided into seven groups: control group (non-vitrified embryos) and six vitrification groups with different cryoprotectant concentrations and exposure times. After vitrification, embryos were cultured for determination of re-expansion and hatching rates. Vitrification with 25% DMSO +25% EG (exposure for 1 min and 20 s) resulted in the highest re-expansion (65.2%) and hatching (68.2%) rates. The lowest re-expansion and hatching rates were observed in vitrification with 12.5% DMSO + 25% EG + 12.5% PG with both tested exposure times (i.e., 3 min + 1 min and 1 min + 20 s). A combination of DMSO + EG is efficient to preserve blastocysts, especially following a short exposure time.