Grouping ewes by lambing date or period (due to synchronisation or ram effect) needs a proper lambing shed organisation, to limit labour and save time. During these periods, issues linked to ewes’ natural behaviour can also occur (e.g. ewes stealing lambs from each others). Moreover, having ewes that are more prolific can also mean more issues of mismothering. Pregnancy scanning ewes to obtain a lambing date/period allows a better organisation of the lambing shed. For each lambing date/period, it is possible to create batches of 10-15 ewes, in a couple of pens. .