Table 4.

Impact of ovarian stimulation of small ovarian reserve heifers with control or Ex-cpFSH doses on stage of nuclear maturation for compact cumulus–oocyte complexes or expanded cumulus–oocyte complexes.

	Exp 1
	Control	Ex-cpFSH
	comCOC	comCOC	expCOC
Number of oocytes evaluated per heifer	9 ± 3 (1–27)	7 ± 1 (1–14)	3 ± 1 (0–9)
Stage of nuclear maturation
GV	77% ± 8% (30–100%)	97% ± 3% (75–100%)	19%±10%**** (0–100%)
GVBD	0% ± 0%	0% ± 0%	1% ± 1% (0–11%)
MI	0% ± 0%	1% ± 3% (0–13%)	40% ± 13%** (0–100%)
MII	0% ± 0%	1% ± 1% (0–13%)	8% ± 5% (0–7%)
Degenerated	2% ± 2% (0–14%)	0.8% ± 1% (0–33%)	8% ± 4% (0–33%)

Small ovarian reserve Holstein heifers (n = 10/dose) were subjected to ovarian stimulation with IS-cpFSH (control) or Ex-cpFSH doses then subjected to OR to recover COCs 12 h after the last cpFSH injection. Proportions per column may not total 100% because some COCs or oocytes were unidentifiable or lost during histological processing to assess nuclear maturation. Data are expressed as mean ± SEM for proportion of ovulatory-size follicles with comCOCs or expCOCs at each nuclear maturation stage per heifer with the range of the data collected in parentheses.

^** P ≤ 0.01,

^**** P ≤ 0.0001 denote statistical differences between means within cpFSH dose based on Type III ANOVA analysis. IS-cpFSH, industry-standard commercial FSH-enriched porcine pituitary preparation; Ex-cpFSH, excessive commercial FSH-enriched porcine pituitary preparation; OR: oocyte retrieval; COCs, cumulus–oocyte complexes; comCOC, compact cumulus–oocyte complex; expCOC, expanded cumulus–oocyte complex; GV, germinal vesicle, GVBD, germinal vesicle breakdown; MI, metaphase I; MII, metaphase II.