Research has been carried out on embryo production from prepubertal heifers. The results show that oocytes recovered during the first collection from 6-month-old calves are less competent than those recovered during subsequent collections. This observation needs to be confirmed and verified by taking into account the weight of the calves. Embryo transfer, resulting in a 75% pregnancy rate, has demonstrated the viability of embryos produced from these prepubertal animals. Furthermore, the subsequent fertility of calves used for oocyte collection six times between the age of six months and puberty has been verified by artificial insemination. At this stage of the project it does not appear that the technology of oocyte collection significantly affects the fertility of the heifers.

This work has been continued with the objective of increasing oocyte competence during maturation in vitro. In collaboration with Dr. Lawrence Smith, it has been shown that the addition of granulosa cells is beneficial for oocyte maturation. However, this effect is not caused by a soluble factor and means that this approach is of little practical importance.In vitro fertilization must be performed with frozen, washed semen from different bulls.

This year, a new product with a polysaccharide base has been evaluated for washing sperm. This product is easier to use and, according to the research hypothesis, protects the semen against the harmful effects of centrifugation and the other in vitro manipulations. The production of embryos by IVF of oocytes from heifers shows that this product is slightly superior to Percoll (56.6 vs 43.5%), the system presently used. This product will now be tested with oocytes from high quality cows before use on a regular basis.