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Evaluation of bull performance based on in vitro fertilization studies

University of British Columbia

The first part of this study investigated if differences among bulls as semen donors, and sperm concentrations affected cleavage rate of oocytes. Three levels of sperm concentration and their effect on cleaving oocytes were analyzed. Frozen-thawed semen samples from five Holstein bulls and oocytes (n=728) harvested from slaughterhouse ovaries were used in this experiment. Oocytes were matured in vitro with Hams' F-10 and estrus cow serum (ECS) media, then fertilized in vitro using Tyrode Albumin Lactate Pyruvate (TALP) media. The resulting embryos were subsequently cultured using Hams' F-10 and fetal calf serum (FCS) in the presence of oviductal cells . The three sperm concentrations used in the study were 2x106, 1x1O6 and 0.5x106 /ml. Approximately 56- 72 h after addition of sperm, cleavage as indicated by a 2-cell stage embryo was observed and recorded. A significant difference (P< 0.001) in cleavage rate was observed among the five bulls. Sperm concentration did not affect cleavage rate. Bull x sperm interaction was also not significant (P>0.05). The in vivo fertility based on 60 - 90 d non-return rate (NRR) to first insemination did not correlate with the in vitro cleavage rate (P>0.05, r = 0.51). In the second part of the study, the same bulls were tested for their ability to cause further embryonic development beyond cleavage to the blastocyst stage. The resulting embryos were frozen at either the morula or blastocyst stage to study the freeze- thaw survival rate. Unlike in the first part of the study, the oocytes were matured in vitro using tissue culture medium (TCM 199) supplemented with superovulated cow serum (SCS), fertilized in vitro using Brackett and Oliphant (BO) media. The embryos were cultured for 7-9 d using TCM 199 medium supplemented with insulin and SCS in the presence of cumulus cell monolayers. Embryos that reached the morula or blastocyst stage were frozen in 0.25 cc straws by controlled freezing and thawing procedure using 1.6 M propylene glycol as a cryoprotectant. No significant differences (P>0.05) were observed among all five bulls in their ability to cause further embryonic development. In addition, the post thaw survival rate of embryos produced by all five bulls following freeze-thaw did not differ significantly (P>0.05). The in vivo fertility based on 60 - 90 d non-return rates (NRR) to the first insemination did not correlate with the in vitro embryonic development and freeze-thaw survival rate (P>0.05). The number and quality of embryos produced using the combination of TCM 199 medium and defined BO media with serum was found to be superior to the combination of Hams' F10 and TALP media with serum.

Thesis/Dissertation

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2009-03-25

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http://hdl.handle.net/2429/6534

Animal Science

University of British Columbia

UBCV

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