23 February 1996

When parent/offspring links can all go wrong

GOOD maternal behaviour allows an exclusive bond to be formed between the ewe and her lambs and encourages early sucking.

Cathy Dwyer gives situations when ewe-lamb bonding fails in Signets latest Sheep and Beef Notes.

&#8226 Inexperienced gimmers, lambing for the first time, have a different physiology, at the moment of birth, to experienced ewes and use different strategies to form a bond with the lamb. Gimmers rely on the smell and taste of amniotic fluids on the lambs coat to be maternal. A ewe which cannot smell will mother all lambs, as she is unable to recognise her own lamb.

A gimmer which cannot smell will not mother any lamb. A few hours exposure to her lamb is sufficient for a gimmer to act in a similar manner to a ewe.

&#8226 Thin ewes at lambing, as well as producing weak lambs and little milk, will also be poor mothers. In the extreme cases the ewe will completely abandon her lamb but otherwise forms only a weak bond with it.

These ewes and lambs are more likely to become separated and seem to maintain greater average distances from one another at grazing, so that the lamb may miss some sucking opportunities.

&#8226 Stress at lambing time should be avoided, as this may disrupt the hormones that help a ewe be maternal. A difficult lambing can also affect maternal behaviour.

&#8226 Lambs do not appear to recognise their own mother until they are at least 12-hours-old.

The birth site is also important. The longer the ewe spends here the stronger the ewe and lamb bond. Ewes are initially attracted to the smell of amniotic fluids, rather than the lamb itself, so moving the lamb away from the birth site may cause the ewe to return to the birth site leaving the lamb behind.

Shelter breaks may encourage a ewe to remain at the birth site longer, as well as providing some protection for the lamb. But ewes do not use shelter unless they require it themselves – a thin ewe will use a shelter more readily than a fit ewe. Ewes also tend to select elevated birth sites, along fence lines or ridges. Siting shelter belts in these areas may encourage ewes to lamb in shelter and so increase lamb survival rates.

&#8226 Avoid stress at lambing.

&#8226 Ensure correct ewe condition.

&#8226 Watch stocking density.

&#8226 Birth site helps bonding.