If you are asking whether onion sets can be planted in freshly manured ground the answer is no... would be too strong for the bulbs.

Here in the desert, we wait two weeks before planting in soil with composted manure, and at least two months when fresh manure was used. Probably you will have to wait much longer in cool climates like the UK, Alan.

Well personally I wouldn't plant in until spring now... particularly as temps. have dropped and we had a dump of snow overnight and this morning...

I agree, fresh manure has too much ammonia & salt. Nothing will grow in that. Let it break down for at least 6 months in an open air location, turning it every few weeks.