Ewe synchronisation is the management practice of achieving a compact mating period and thereby compact lambing period
. Having the majority of lambs at a uniform age has significant benefits from birth through until slaughter (or tupping/sales), as management practices can be efficiently carried out across the majority of the flock at the same time, e.g. Heptavac P vaccinations in young lambs. A compact lambing period means that the increased frequency of checks and increased staffing required at lambing is needed for a shorter period; this can be especially helpful for smallholders and can reduce neonatal lamb losses and improve neonatal lamb care, resulting in thriftier lambs. It also allows the flock to be lambed in two distinct batches which can be useful if shed size is limited. Ewe synchronisation can also be used to advance the breeding season by four to six weeks. Early lambing can yield significant economic benefits for some sheep farmers by meeting the demand for spring lamb and enabling pedigree flocks to produce lambs for the autumn sales.
Ewe synchronisation can be achieved by inserting intravaginal progesterone sponges or the progesterone containing CIDR Ovis intravaginal devices. Once the sponge or CIDR is removed, the ewe’s progesterone levels fall rapidly, which leads to oestrus activity within 36-48 hours. Depending on the specific aims of ewe synchronisation, a PMSG injection may also be used. A ram to ewe ratio of 1:10 will be needed for synchronised ewes. Ewes should be at condition score of 2.5-3.5 to maximise efficacy.
Melatonin implants are another option for advancing the breeding season. They can bring forward lambing by two months but don’t synchronise the ewes so very high ram to ewe ratios are not necessary.