|Chase, Chadwick - Chad|
|Cushman, Robert - Bob|
|AMUNDSON, OLIVIA - South Dakota State University|
|PERRY, GEORGE - South Dakota State University|
|TENLEY, S - University Of Nebraska|
|WOOD, J - University Of Nebraska|
|CUPP, ANDREA - University Of Nebraska|
|Vallet, Jeffrey - Jeff|
Submitted to: Reproduction, Fertility and Development
Publication Type: Abstract Only
Publication Acceptance Date: 8/4/2015
Publication Date: 12/1/2015
Citation: Chase Jr., C.C., Cushman, R.A., McNeel, A.K., Amundson, O.L., Perry, G.A., Tenley, S.C., Wood, J.R., Cupp, A.S., Vallet, J.L., Miles, J.R. 2016. In vitro fertilization (IVF) using semi-defined culture conditions from low or high antral follicle count pubertal beef heifers. Reproduction, Fertility and Development. 28(1-2):221.
Technical Abstract: To compare the in vitro fertilization (IVF) and production (IVP) of embryos from low and high antral follicle count (AFC) heifers, AFC were determined on 106 heifers using transrectal ultrasonography. Ten heifers with the lowest AFC (avg. 13.2) and 10 heifers with the highest AFC (avg. 27.4) with evidence of estrous cyclicity were synchronized with two injections of PGF2a and one-half were harvested on d 5 to 6 and one-half on d 15 to 16 of the estrous cycle. The IVF procedures included protocols for semi-defined media and were as described (P.J. Hansen’s Laboratory, IVP Protocol). Cumulus-oocyte complexes (COCs) from follicles less than 8 mm in diameter were cultured in maturation medium (5% CO2; 38.5°C) for 24 h. Matured COCs were fertilized using thawed frozen semen from a crossbred bull that was purified using Percoll separation procedures. Motile spermatozoa were added to COCs in fertilization medium at a final concentration of 1 x 106 spermatozoa per mL. About 24 h later, presumptive zygotes were placed in microdrops of development medium under oil, and cultured (5% CO2; 5% O2; balance N2; 38.5°C). On d 3 and 8 after fertilization, cleavage and blastocyst development rates, respectively, were assessed. Data were analyzed using the MIXED procedure of SAS and the model included the effects of collection d, group (high or low AFC), and their interaction. More COCs (P < 0.0005) were collected from high than low AFC heifers (30.3 vs. 9.3 ± 3.12 per heifer). Both the number and percentage of COCs that cleaved had an interaction between collection d and group (P < 0.03). The interaction appeared to be due to low cleavage and development rates on one of four collection d (appeared not related to d of estrous cycle). Although high compared to low AFC heifers had more COCs that cleaved (18.7 vs. 4.4 ± 1.84 per heifer), the percentage of cleaved COCs did not differ (59.2 vs. 49.8 ± 3.36%). There were no significant differences between high and low AFC heifers in the number of blastocysts (3.1 vs. 0.6 ± 1.21 per heifer) or in the percentage of COCs that developed to blastocysts (8.8 vs. 5.2 ± 3.60%). In previous replicates (years), we reported that high AFC heifers had more COCs collected, more COCs that cleaved, and more COCs that developed to blastocysts than low AFC heifers. In contrast, in this study numbers of COCs that developed to blastocysts did not significantly differ between high and low AFC heifers. Additionally, the percentage of COCs that cleaved, and that developed to blastocyst have been similar between high and low AFC heifers. Therefore, high compared to low AFC heifers may produce more IVP embryos; however, AFC does not appear to affect the competence of an oocyte to develop and mature to the blastocyst stage.