Causes of lamb loss
The loss of lambs around the time of pregnancy is costly due to the investment in getting the ewe to the stage of lambing. 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 may also lengthen the oestrus cycle by 1 or 2 days, dampen oestrus behaviour towards rams and reduce the length of time ewes are 'in heat'. Young, maiden ewes are more likely to suffer embryo mortality than older ewes.
Poor feeding of lambs
If newborn lambs cannot get milk due to sucking on damaged teats, they will rapidly lose their urge to suckle - about 6 hours after birth - and subsequently die. Read more about reducing udder damage in ewes.
Environmental conditions and lamb loss
Cold, wet weather increases lamb mortality significantly, so it's important to choose the right time of year to join and breed your ewes. Keeping your herd healthy, monitoring what they eat and ensuring there is sufficient shelter in the paddock all improve your chances of a successful breeding program.
For more information, read the Australian Wool Innovation factsheet on improving lamb survival (PDF, 124KB).
Predators of lambs
The main predators of young lambs are wild dogs, foxes and feral pigs. They often 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. Find out more about protecting sheep and lambs from predators.
Ewe diseases that cause lamb losses
Pregnancy toxaemia (lambing sickness) and hypocalcaemia (milk fever) are metabolic diseases that can affect ewes in the late stages of pregnancy.
Lambing sickness is usually the most common of these diseases, which in severe cases causes high losses of ewes and lambs. These diseases often initially appear similar, can be triggered by similar factors, and can occur together.
First indications that late-pregnant ewes are affected by one of these diseases are often seen during mustering or yarding for the pre-lambing shearing or crutching.
These diseases are fatal if left untreated. To be effective, appropriate treatment must be given early.
Find out more about lambing sickness and milk fever in ewes.