RESUMO
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.
Assuntos
Transferência Embrionária , Resultado da Gravidez/veterinária , Prenhez , Gravidez Múltipla , Animais , Animais Recém-Nascidos , Bovinos , Ciclo Estral , Fazendas , Feminino , Fertilização in vitro , Freemartinismo/genética , Trabalho de Parto Induzido/veterinária , Masculino , Mortalidade , Gravidez , Taxa de GravidezRESUMO
A tandem fusion involving chromosome 4 and chromosome 21 of the bovine karyotype, is described in a newborn Holstein-Friesian heifer which was also a blood chimera exhibiting female cells of normal bovine karyotype and male cells with a 59, XY + tan (4:21). The rearranged chromosome was a dicentric and the longest acrocentric in the male cells. Apart from the features characteristic of the freemartin condition, no other phenotypic abnormalities were detected in the heifer calf. Since the heifer and other calves of the herd were not eartagged at birth, 20 newborn bull calves of the same age in the herd were analyzed in an attempt to identify the male born co-twin to the heifer. However, this effort proved unsuccessful, probably because the co-twin had died in utero or was erroneously included among the calves sent to the slaughter house.