Lamb loss in ewes
Ensuring good conception rates in a flock, through healthy sheep and well-managed joining, can have a significant impact on profit.
The loss of lambs is especially costly due to the investment in getting the ewe to the stage of lambing. Identifying when lamb loss is occurring is crucial to determine the cause. Pregnancy scanning is the most useful tool to determine this and is even more valuable when combined with assessing 'wet and dry' ewes at lamb marking.
There are many factors that can cause lamb loss, all of which can be reduced with good management.
Lamb death in utero
During the first 9 days following fertilisation it's vital to keep the ewes cool, as heat stress can cause embryo mortality.
High temperatures can also:
- lengthen the oestrus cycle by 1 or 2 days
- dampen oestrus behaviour towards rams
- reduce the length of time ewes are 'in heat'.
Foetal losses in pregnancy are usually relatively low. Young maiden ewes are more likely to suffer foetal mortality than older ewes. Some toxins and infections can cause losses.
If newborn lambs cannot get milk they will lose their urge to suckle about 6 hours after birth, and subsequently die.
Many factors can affect a lamb's ability to suckle including:
- damaged teats
- lamb birth weight.
Ewe body condition score, especially in late gestation, has a significant impact on lamb birth weight, survival and lifetime productivity.
Cold, wet weather increases lamb mortality significantly, so it's important to:
- choose the right time of year to join and breed your ewes
- select the best paddock for feed quantity/quality, worm risk and shelter
- choose appropriate mob sizes and pregnancy scanning to manage mismothering
- shear or crutch at appropriate times.
The main predators of young lambs are wild dogs, foxes and feral pigs. They account for 5–10% of lamb losses (and in some situations much more).
Keeping paddocks secure and baiting and trapping will help, but you may need to adopt a more strict control strategy.
Pregnancy toxaemia (lambing sickness) and hypocalcaemia (milk fever) are metabolic diseases that can affect ewes in the late stages of pregnancy and early postpartum.
The nutritional requirements for a twin-bearing ewe in late pregnancy are 1.8 times that of a dry ewe. Ensure ewes are healthy, have adequate nutrition and avoid stressing ewes or holding them off feed, such as in yards without roughage.
Ensuring ewes are healthy through preventative health will also help produce healthy lambs. You should implement:
- vaccination and parasite control programs
- close monitoring of health and prompt treatment
- good biosecurity.
Read the Australian Wool Innovation fact sheet on improving lamb survival (PDF, 124KB) for more information.
- Last reviewed: 22 Nov 2022
- Last updated: 25 Nov 2022