CHAPTER 1
 LITERATURE REVIEW

 In Vitro Embryo Production in Cattle

 Over the past 25 years, since the birth of the first calf following in vitro fertilization

(Brackett et al., 1982), significant advances in the techniques for in vitro embryo production

have been made. Such improvements have led to a dramatic increase in the use of in vitro

produced embryos in the cattle industry. According to records collected by the International

Embryo Transfer Society (IETS), more than 265,000 in vitro produced embryos were transferred

worldwide in 2005 compared with less than 42,000 in 2000, a more than six-fold increase in 5

years (Thibier, 2001, 2006). Further increases in the future are likely given the potential

applications of in vitro embryo production systems within the beef and dairy industries.

 While there is great potential for in vitro embryo production, the actual use of this

technology is still very limited. According to the IETS, in 2005, only 30% of all embryos

transferred worldwide were produced in vitro (Thibier, 2006). It is well recognized that embryos

produced in vitro differ from their in vivo derived counterparts in terms of morphology and

physiology. Such differences can affect the post-culture viability of bovine embryos which

limits the use of in vitro embryo transfer in commercial settings.

Potential Applications of In Vitro Embryo Technologies

Enhance genetic selection

 In vitro embryo technologies have great potential for improving the rate of genetic gain for

quantitative traits important for meat and milk production. Both the intensity and accuracy of

selection for quantitative traits can be improved through the use of in vitro embryo production

(Hansen and Block, 2004). In addition, in vitro embryo production systems can reduce the

generation interval through the production of embryos from pregnant animals (Kruip et al., 1994)