| Summary: | <p><strong>Context: </strong>The number of developmentally competent cumulus–oocyte complexes (COCs) retrieved during Ovum Pick-Up (OPU) determines success in both bovine and human assisted reproduction. Follicular flushing for COC retrieval is practicsed widely in humans but not in cattle.</p>
<p><strong>Aims: </strong>To determine the benefits of follicular flushing in cattle and assess the merits of a novel 16G double-lumen needle (‘OxIVF’) that flushes laterally to the needle shaft.</p>
<p><strong>Methods: </strong>Experiment 1 flushed 655 antral follicles (≥7 mm) from 255 abattoir-derived cattle ovaries. In Experiment 2, 12 Holstein heifers underwent two cycles of OPU in a cross-over design comparing both needle types. In Experiment 3, 11 Holstein heifers underwent two cycles of OPU using the OxIVF needle in a cross-over design: flushing (≥7 mm follicles) vs a ‘Hybrid’ approach of flushing (≥7 mm follicles) and aspiration (5–7 mm follicles); followed by two cycles of standard follicle aspiration (>5 mm follicles).</p>
<p><strong>Key results: </strong>In Experiment 1, COC recovery was greater (<em>P</em> = 0.034) for the OxIVF vs Standard needle (mean ± s.e.; 74.1 ± 2.10% vs 67.0 ± 2.23%); yield of Grade 1 COCs was also greater (20.1 ± 1.97% vs 8.2 ± 1.38%; <em>P</em> < 0.001). In Experiment 2, recovery of COCs was greater (<em>P</em> = 0.045) for the OxIVF vs Standard needle (89.1 ± 2.98% vs 79.6 ± 3.47%). Day 6 embryo yield was also greater (<em>P</em> = 0.017) for the OxIVF vs Standard needle (87.2 ± 4.38% vs 67.6 ± 6.73%). In Experiment 3, recovery of COCs was greater (<em>P</em> = 0.033) for ‘Flush’ vs ‘Aspirate’ groups (82.1 ± 5.06% vs 66.2 ± 3.48%). However, number of Day 8 blastocysts for the ‘Hybrid’ vs ‘Flush’ approach (9.2 ± 1.39 vs 6.5 ± 1.05 per cycle) did not reach statistical significance.</p>
<p><strong>Conclusions: </strong>Follicular flushing using the OxIVF needle, embracing the ‘Hybrid’ approach, has the potential to increase oocyte retrieval and blastocyst number per donor cycle in cattle but requires further validation.</p>
<p><strong>Implications: </strong>Larger scale studies will seek to confirm benefits of follicular flushing using the OxIVF needle in cattle. Future studies should consider applications in both equine and human assisted reproduction.</p>
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