Ovarian follicular dynamics, follicle deviation, and oocyte yield in Gyr breed (Bos indicus) cows undergoing repeated ovum pick-up.
The objective of this study was to evaluate ovarian follicular dynamics during intervals between successive ovum pick-up (OPU) and determine its effects on the number and quality of recovered cumulus-oocyte complexes (COCs) in Zebu cows (Bos indicus). Pluriparous nonlactating Gyr cows (Bos indicus; n=10) underwent four consecutive OPU sessions at 96-h intervals. The dynamics of ovarian follicular growth between OPU sessions was monitored by twice-daily ultrasonographic examinations. A single dominant follicle (DF) or two codominant (CDF) follicles (>9mm) were present in 63.3% (19 of 30) of intervals studied, with follicle deviation beginning when the future dominant follicle (F1) achieved a diameter of 6.2+/-0.3mm. The phenomenon of codominance was observed in four (13.3%) of the inter-OPU intervals. The remaining intervals (36.6%, 11 of 30) were characterized by a greater follicular population, lower rate of follicular growth, and a smaller diameter F1 (P<0.0001). There was a tendency (P=0.08) toward an increase in the number of recovered COCs when dominant follicles were not present (NDF). The quality of COCs was not affected by the presence of a single dominant follicle, but codominant follicles resulted in recovery of a lower proportion of viable embryos (40.0%, 62.1%, and 63.6%; P<0.05) and higher proportions of degenerate COCs (56.0%, 30.3%, and 28.6%; P<0.05) for CDF, NDF, and DF respectively. We concluded that, in Zebu cows, (a) repeated follicle aspirations altered ovarian follicular dynamics, perhaps by increasing follicular growth rate; (b) follicular dominance could be established in cows undergoing twice-a-week OPU; and (c) the presence of a dominant follicle during short inter-OPU intervals may not affect COC quality, except when a codominant follicle was present.
Viana
J H M
JH
Embrapa Dairy Cattle Research Center, Juiz de Fora, MG, Brazil. jhmviana@cnpgl.embrapa.br
Palhao
M P
MP
Siqueira
L G B
LG
Fonseca
J F
JF
Camargo
L S A
LS
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002452:Cell Count; D054885:Cumulus Cells / Q000166:cytology / Q000502:physiology; D005260:Female; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D013396:Suction; D020858:Tissue and Organ Harvesting / Q000379:methods / Q000662:veterinary*; D014463:Ultrasonography
D011374:Progesterone