Table 3.

Impact of ovarian stimulation of small ovarian reserve heifers with control or Ex-cpFSH doses on morphology of cumulus–oocyte complexes.

Morphological classification of COCs	Exp 1		Exp 2		Exp 3
	Control	Ex-cpFSH	Control	Ex-cpFSH	Control	Ex-cpFSH
comCOC	93% ± 3% (75–100%)	77% ± 4%** (58–100%)	46% ± 9% (0–100%)	72% ± 5%** (27–100%)	91% ± 3% (0–94%)	65% ±5%**** (40–100%)
expCOC	0% ± 0.4% (0–4%)	22% ± 5%**** (0–42%)	45% ± 8% (0–100%)	24% ± 4%* (0–39%)	3% ± 2% (0–29%)	32% ±5%**** (0–82%)
Denuded	3% ± 3% (0–25%)	0.7% ± 1% (0–7%)	7% ± 2% (0–25%)	4% ± 1% (0–17%)	6% ± 3% (0–44%)	3% ± 1% (0–18%)

The small ovarian reserve Holstein heifers in Exp 1 (n = 10/dose) and 3 (n = 18/dose) were subjected to OR to recover COCs 12 h after the last cpFSH injection while the heifers in Exp 2 (n = 16/dose) were subjected to an ovulatory hCG stimulus 12 h after the last cpFSH injection, and COCs were recovered by OR 24 h after the hCG injection but before ovulation. 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 proportions of ovulatory-size follicles per heifer with COCs classified as comCOC, expCOC, or denuded with the range of the data collected in parentheses.

^* P ≤ 0.05,

^** P ≤ 0.01,

^**** P ≤ 0.0001 denote statistical differences between means within each experiment based on Type III ANOVA analysis. Exp, experiment; 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.