Studies on the physiology of gamete maturation and transport, fertilization and early embryo development in farmed red deer (Cervus elaphus scoticus) and application to in vitro embryo production

The aim was to develop an improved in vitro embryo production system for farmed red deer (Cervus elaphus) in which little is known about the physiological events surrounding fertilization and early embryo development. The temporal relationship between in vivo gamete maturation, fertilization, embryonic development, LH and estrus was investigated to serve as a baseline for in vitro studies and found to be similar to those in domestic ruminants, except that no embryos prior to the blastocyst stage were ever found in the uterus. In Chapters 2 and 4, in vitro systems were compared for their ability to maintain sperm motility and support fertilization. Sperm motility was maintained on epithelial oviduct monolayers but fertilization remained low. Incorporation of 20% sheep serum maintained sperm motility and increased fertilization {dollar}>{dollar}80%, however, resulted in 40% polyspermia which decreased by 75% at lowered sperm and sheep serum concentrations. Embryo viability before and after in vitro embryo culture was determined in oviducts of red deer recipients. Pregnancy and calving rates were similar to in vivo controls when transferred before culture, however decreased viability was associated with embryo culture. In Chapter 5, traditional in vitro embryo culture systems were compared for their ability to support development of in vivo presumptive zygotes to the morula and blastocytes stage. All culture systems supported embryo development but development to blastocysts was lower than for domestic ruminants. Chapter 6 investigated hybridizing red deer oocytes with wapiti and Pere David's sperm using in vitro fertilization methods. Sperm from the closely related wapiti fertilized a greater proportion of oocytes using bovine in vitro fertilization system whereas Pere David's sperm needed in vitro conditions similar to red deer. Pere David's F1 hybrids had delayed insemination-cleavage interval. However, only embryos developing similarly to red deer controls were viable upon transfer. A 20% decrease in embryo viability was associated with in vitro embryo culture for the wapiti hybrid embryo. Thus, viable cervine embryos can be produced by in vitro methods however, in vitro embryo culture systems may require further development.