|Chase, Chadwick - Chad|
|Cushman, Robert - Bob|
|PERRY, GEORGE - South Dakota State University|
|CUPP, ANDREA - University Of Nebraska|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2014
Publication Date: 10/1/2014
Citation: Chase, Jr., C.C., Wright, E.C., McNeel, A.K., Cushman, R.A., Perry, G.A., Cupp, A.S., Vallet, J.L., Sypherd, D.D., Miles, J.R. 2014. Effect of high and low antral follicle count in pubertal beef heifers on in vitro fertilization (IVF) [abstract]. American Embryo Transfer Association/Canadian Embryo Transfer Association Joint Convention Proceedings, October 6-8, 2014, Middleton, Wisconsin. 49.
Technical Abstract: Pubertal heifers can be classified between those with high (= 25) and low (= 15) antral follicle counts (AFC). The objective of this study was to determine oocyte development and maturation (e.g., fertility) in an in vitro fertilization (IVF) system for high and low AFC heifers. From a pool of 120 heifers, 10 high and 10 low AFC heifers determined by transrectal ultrasonography and all with evidence of estrous cyclicity (i.e., pubertal) were synchronized with two 5 mL injections of PGF2a 11 days apart. Heifers were sacrificed over 4 days on days 15 to 16 of the synchronized estrous cycle. A total of 15 heifers (n = 7 high and n = 8 low AFC) were at the appropriate stage of the estrous cycle. Ovaries were collected and transported to the laboratory. Follicles less than 8 mm in diameter were aspirated. The IVF procedures and media were as previously described (Miles et al., 2004. Biol. Reprod. 71, 1919-1926). Cumulus-oocyte complexes (COCs) were identified and washed in oocyte collection medium and then in maturation medium and were cultured (5% CO2; 38.5°C) for 24 h. Following maturation, COCs were transferred and washed in fertilization medium. Thawed frozen semen from a crossbred bull was subjected to swim-up procedure. Motile spermatozoa were collected and added to COCs to yield a final concentration of 1 x 106 spermatozoa per mL of fertilization medium. About 24 h later, presumptive zygotes were washed in development medium, placed in micro drops of development medium, and cultured for 8 days. On day 3 and 8 after fertilization, cleavage and blastocyst development, respectively, were assessed. Data were analyzed using the Proc Mixed procedure of SAS and the model included the effects of day of collection (n = 4), group (high n = 7 or low n = 8 AFC heifers), and the interaction. The interaction did not differ (P = 0.10). Day of collection influenced (P < 0.05) the number of COCs and the number of oocytes cleaved. High compared to low AFC heifers had greater (P < 0.05) numbers of COCs (42.7±4.66 vs. 22.1±4.59), oocytes that cleaved (28.1±3.60 vs. 15.9±3.55), and developed to blastocysts (13.2±1.71 vs. 6.2±1.69). However, there was no difference (P > 0.10) in the percentage of COCs that cleaved (65.3±5.58 vs. 66.2±5.50%, high vs. low, respectively) or that developed to blastocysts (46.7±6.75 vs. 42.2±6.65%). In conclusion, AFC did not appear to affect oocyte development and maturation through the blastocyst stage.