Important principles to increase lamb survival
MLA & AWI July 31, 2024
Most lamb loss occurs during the first three days after birth, so focus on factors that can improve survival of newborn lambs to reduce lamb losses. As the condition score of ewes at lambing increases, so does lamb survival, especially in twin-bearing ewes. Target condition score at lambing for a twin-bearing ewe is CS 3.3.
Important principles to increase lamb survival include:
- Select a lambing time that is likely to maximise survival of newborn lambs.
- Ewe condition at lambing is the most important determinant of lamb survival, due to its effect on lamb birthweight.
- Optimum ewe nutrition in the lead-up to lambing will assist the ewe in delivering in a timely fashion, decreasing the risk of dystocia.
- Cold, wet and windy weather increases lamb mortality, particularly with low-birthweight lambs. Manage ewes to minimise the impact of weather at lambing.
- Plan to have sheltered paddocks available for lambing.
- The effects of prolonged birth and the combination of hunger and mismothering account for most lamb deaths.
- If ewe nutrition is poor, there is delayed production of colostrum and newborn lambs are at risk if they do not receive a drink soon after birth. In addition, mothering ability and lamb behaviour are depressed when ewe nutrition is poor.
- The longer the ewe stays at the birth site, the greater the chance of the ewe and lamb forming a bond, thereby reducing the risk of mismothering.
- Depending on the ewe and the breed type, it can take up to six hours for a ewe to recognise her lamb and in this time a ewe may accept any lamb as her own. It takes lambs twice as long to recognise their mothers and if a lamb is abandoned within six hours of birth it has little chance of survival.
- Ewes about to give birth may ‘pirate’ recently born lambs only to abandon them when their own lamb is born.
- When the number of ewes lambing is at its peak, the lambing paddock is a busy and cluttered place. Best practice is to minimise any unnecessary disturbance in the lambing flock.
- Predators can account for 5–10% of losses in some situations. But predators are usually of secondary importance compared with hunger, mismothering and hypothermia. To prevent this situation occurring, start baiting well before lambing and continue well into lambing.
Aim for lamb survival targets higher than:
- Merino ewes: single bearing – 90% survival; twin bearing – 70% survival
- Crossbred ewes: single bearing – 90% survival; twin bearing – 80% survival
In the period from three days after birth to weaning, aim to keep lamb mortality rates to less than 3%.
Lamb marking and mulesing
Losses between marking and weaning are normally less than 1%. Time lamb marking and mulesing for about two weeks after the last possible lambing date. Hygiene is most important for equipment.
Conduct mulesing in accordance with industry guidelines. Use an experienced operator and appropriate anaesthesia and analgesia. If mulesing is conducted when flystrike is possible, treat healing wounds with an approved and registered product to prevent flystrike.
Use anaesthesia and analgesia for all lamb-marking procedures. Consult with an animal health advisor for more information or check out Best practice lamb marking for more information.
Carry out marking and mulesing in clean yards close to the paddock being grazed and ensure the operation is completed early in the day so ewes and lambs can successfully mother-up following the marking and mulesing procedures.
For guidelines on additional health treatments, refer to MMFS Module 11 Healthy and Contented Sheep.
Wet and dry ewes at lamb marking
Small but consistent gains can be made towards weaning more lambs by removing ewes that lamb but fail to rear their young. The ‘wet and dry’ technique is used to identify ewes that are either rearing a lamb, have lambed and lost, or lost their lamb during pregnancy. Ewes who are rearing a lamb will have a full, warm udder with clean teats. Ewes who have lambed and lost generally have birth stain on the breech and some udder development but tend to have clear fluid when milked and teats that are dirty. Dry ewes have no birth stain on the breech and little udder development.
Ewe rearing ability is repeatable, meaning the ewes in your flock that successfully rear lambs are more likely to do it year after year, constantly improving lamb survival.
Imprint feeding lambs before weaning
Train lambs to eat feed supplements by ‘imprint’ feeding before weaning. Feed lambs at least 4–6 times while with their mothers using the supplements most commonly used on–farm. At least 90% of the lambs should be coming to the feed and eating. The idea is to introduce the lambs to feed so they can recognise the supplement after they are weaned.