In outdoor lambing systems, half of lamb deaths occur on the first day of birth, with 75% of these deaths happening before the lamb reaches three days old.
To minimise these early deaths, it is essential to optimise the bond between ewe and lamb to promote successful lamb rearing.
Two days prior to lambing, changes in oestrogen and progesterone levels cause ewe behaviour to change. These behaviours include isolation, shelter seeking and choice of birth site. The birth site is important – the longer the ewe spends there with her lambs, the stronger the bond between them, preventing mismothering and reducing risk of accidents or predation.
When labour begins, the ewe’s hormonal state changes further. She shows an attraction for amniotic fluids, which causes her to lick the ground when her water bag breaks. When she lambs, she releases oxytocin, a hormone which promotes maternal bonding behaviour. The presence of the lamb then lets her demonstrate maternal behaviour.
At birth, the ewe transfers attraction for amniotic fluids at the birth site to amniotic fluids in the lamb’s coat by licking the lamb. This stage of the bonding occurs within 30-60 minutes of lambing. This allows her to identify the lamb (s) as her own, meaning this period of licking and smelling the lamb is vital for the ewe to mother her own lamb, to create the maternal bond.
The licking and mothering process also helps to dry the lamb and for it to find the udder to suckle. Suckling also creates a bond from the lamb to the ewe. It allows the lamb to have a rapid intake of sufficient colostrum, allowing for passive transfer of immunoglobulins, again promoting survival.
Recognition of the lamb by the ewe is initially through smell, followed by sight and then sound as it bleats. Following this process, the ewe can identify which lamb is hers, with other lambs being rejected.
The lamb also has a role to play in that it needs sufficient activity and co-ordination to stand, seek the udder and suck. Sucking enables the lamb to recognise and maintain a bond with the ewe.
Sometimes this bonding process can go wrong. Examples of this include the following:
Poor nutrition in late pregnancy: which disrupts the hormonal profile in ewes as well as the quality and quantity of colostrum production. The last 35 days of pregnancy, the ‘golden 35 days’, gives flock managers the greatest opportunity to influence lamb survival and vigour.
A difficult birth: pain and stress may disturb normal signalling and ewes may fail to interact in the 30 to 60-minute window.
Stress at lambing: ewes can delay lambing if the environment around them is perceived as dangerous. This can lead to less bonding, drying of the lamb and sucking.
Disturbance at the birth site: limits the efficacy of transferring attachment from amniotic fluids to the lamb.
Genetics: some ewes are genetically predisposed to show less maternal behaviour than others. In addition, lamb vigour has genetic variability – some rams sire lambs that stand and suckle quicker than others.
Inexperienced ewes: first-time lambers are more sensitive to disturbance at lambing and may not bond readily with their lambs if not given time and space.
Ewe and lamb behaviour contributes greatly to lamb survival in outdoor systems and by working with the biology of the ewe, will help give her the best opportunity to bond to her lambs and raise them herself successfully.
Outdoor lambing systems allow for greater opportunity, compared to indoor, for the ewe to find a good birth site, have space, and to have minimal disturbance before and after lambing, helping to optimise her bond with her lambs.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here