Effect of oestrous synchrony between embryo donors and recipients,embryo quality and state on the pregnancy rate in beef cattle

This study aimed to evaluate the effect of oestrous synchrony between donors and recipients and the embryo quality on the pregnancy rate in beef cow recipients. The experiment was performed over two years at an embryo transfer (ET ) centre in Southern Brazil. Ninety Aberdeen Angus cows were subjected to superovulation (SOV ) protocols, resulting in the recovery of 1,048 transferable embryos. Eleven groups were formed with intervals of 6 hr, from ?30 to +30 hr, with respect to recipient versus donor oestrous detection. Evaluation of embryo quality was according to the IETS guidelines. The overall pregnancy rate was 52%. Effects related to donor and recipient oestrous synchronization on pregnancy rate were observed (p  =  .01), ranging from 36% to 50%. The embryo quality rate affected the pregnancy rate, where Grade I resulted in 57% and Grade III in 43% of pregnancy (p  <  .001). The embryonic state (frozen or fresh) showed no (p  >  .05) effect on pregnancy rate: 53% for fresh embryos and 44% for frozen embryos. The odds ratio for explanatory variables causing pregnancy indicated that Grade III embryos had 31% less chance of conception compared to Grade I. Thus, oestrous synchrony between donor and recipient, considering ±30 hr apart, can affect the pregnancy rate along with embryo quality.     

Cloning and sequencing of the ovine gamma-interferon gene

Cytokines are major modulators of the immune system of all animals. The cloning and expression of recombinant cytokine genes have permitted the analysis of their immune function and role in the control of the immune response to disease and vaccination. While human, murine, and bovine genes have been cloned and sequenced, the cloning of ovine cytokine genes has not yet been reported. As sheep are of dominant economic importance to the Australian farming industry, it is of significance to clone and express these genes to facilitate the development of new and better vaccines and pharmaceuticals. We have initially selected ovine gamma-interferon (gamma-IFN) as a target cytokine gene. By the use of the polymerase chain reaction (PCR), using primers based on the bovine gamma-interferon sequence, we have amplified the ovine gamma-interferon gene from crude messenger RNA extracted from lymphocytes. After cloning and DNA sequencing the gene, we found that ovine gamma-IFN is 93% identical to bovine gamma-IFN in amino acid sequence. This result indicates that the PCR method will be a rapid and efficient means for cloning other ovine cytokine genes.