Why are lamb losses so high and how to reduce them
Winter is drawing to a close, however it is still cold across a large portion of Australia and lambing season is well underway. With so many risks in lambing emphasized by the colder weather, lamb mortality is unfortunately high for a lot of Australian farmers. An outlining of facts that will assist the profitability your lamb season can be seen below.
Lamb loss causes
Studies show that 80% of lamb deaths occur in the first 48 hours of their life (conducted in Australia). In this trial the most common cause for their death was starvation/mismotherment accounting for 25%. Second was stillbirths at 21% followed by injury (19%), dystocia (9%), predation (7%), cold and exposure (5%), and infection (1%). There was 4% of undiagnosed deaths. In this study single lambs were more likely to die from stillbirth or dystocia, while twin lambs had a higher chance of dying from starvation or birth injury.
How to determine cause of death
You can collect the lambs and submit them to a veterinarian for postmortem examination. There are tell tale signs that can provide evidence of the reason of death which are body weight, girth, and crown rump length, as well as external signals. For more information about diagnosing lamb mortality click here.
Lambs with a low body weight have trouble maintaining body temperature. All lambs have a high surface area to body weight ratio, especially those under the 3-4 kg mark and can rapidly lose energy if left exposed. In general lambs are not tolerant of wind and having pasture higher than 10cm improves their survival chance as they are able to take shelter from the weather. Windbreaks and animal shelters will also improve their survival chances.
Twin bearing ewes have higher rates of lamb survival if lambing in smaller lots (100-200). Maidens are inexperienced and are more likely to ignore their lamb’s attempt to suckle. Pasture should be available in the highest amounts for twin bearing ewes to avoid ewes walking away from their lambs looking for food.
In sheep the mothering ability is a reoccurring process therefore if a ewe fails to rear a lamb one year it is a good candidate for culling. Good maternal instincts are enhanced in a flock by the following:
- Choosing ewes that are early to conceive and bear twins
- At lamb marking, remove ewes that have failed to rear a lamb and tag those that have had pregnancy complications
- Avoid interruptions to lambing like chasing with dogs or driving in the paddock if the sheep are not accustomed to loud noises
- Select and manage ewes for lower rates of dystocia
- Good fencing and predator control.
Selecting the right genetics for fertility
You can positively influence ewe fertility by selecting sires with Australian Sheep Breeding Values. To view the values click here.
To find out other ways to increase lambing success for ewe lambs and maidens click here.