Epigenéticos de la criopreservación y la consanguinidad en el vacuno lechero

Abstract

It is well known that cryopreservation can lead to DNA damage and decreased sperm motility. Epigenetic changes/abnormalities have also recently been shown to be transgenerational. Certain advanced reproductive technologies can increase the risk of epigenetic abnormalities in the embryo, and preliminary data in our laboratory has shown that murine sperm cryopreservation can lead to changes in the expression of imprinted genes, with these changes possibly exacerbated in inbred strains. This is a potential problem for the Australian Dairy cattle industry, as inbreeding values are increasing yearly in several breeds, such as Australian Jersey cattle (Wiggans et al., 1997). The current research described here may be useful in promoting breeding strategies that minimize inbreeding by farmers. 6 inbred and 7 outbred bulls were evaluated. All fresh semen successfully passed quality control parameters established at Genetics Australia. Both fresh and frozen semen was used for in vitro fertilization and blastocyst rates recorded. In general, there was a higher percentage of blastocysts produced from frozen semen in outbred bulls (avg. 26.0%) than in inbred bulls (avg. fresh 21.3% and avg. frozen 20.9%). All blastocysts were frozen and gene expression analysis of these embryos is currently in progress by both microarray analysis and qPCR.