Ewes too good to lose in winter
Wool and sheep producers are being encouraged to assess how highly they value pregnant ewes and this winter manage these animals to optimise production.
Lifetime Ewe Management (LTEM) and Making More from Sheep (MMfS) program researchers have estimated the opportunity cost for a maiden ewe is about $215, rising to $300 for a twin bearing ewe.
They said this meant it paid to feed ewes adequately.
The key driver of sheep reproduction is ewe condition score at joining and lambing.
Condition at joining sets the potential lambing rate. Ewes in good condition at this time can achieve mob pregnancy rates of 90 per cent and 15 per cent or more have potential to be twin bearing ewes.
Ewe condition at lambing impacts on lamb and ewe survival. The better the condition score of the ewe, the higher the survival rate of the lamb.
Maintaining pregnant ewes above condition score 2.5 during winter and at lambing leads to high survival rates and higher productivity during the lamb’s lifetime.
Any ewes below condition score two at this time of the year are at high risk and should be managed separately.
There have been recent reports of ewe deaths in the last month of pregnancy and these are most likely caused by pregnancy toxaemia.
This condition in pregnant sheep is caused by insufficient energy intake or sudden diet changes. Twin bearing ewes are more susceptible and affected animals are not necessarily in poor condition.
Sheep affected by pregnancy toxaemia progressively show a range of clinical signs, but a good initial clue is weak animals that are unable to flee when approached.
Treatment for pregnancy toxaemia includes an oral supplement containing propylene glycol, glycerol or glucose and injections of slow release compounds under the skin that contain calcium, magnesium and glucose.
Affected sheep need to be given the oral energy drench at least twice per day for several days.
The aim of this treatment is to improve the appetite of the pregnant ewe so she begins eating again.
The response to treatment of affected sheep is reasonably good when detected early, but declines when the animal goes down.
But if the affected animal is showing severe nervous signs, the response to treatment could be poor and the animal should be euthanized immediately.
The best approach is prevention, as ewes are too valuable to lose.
This highlights the importance of monitoring ewe condition score and implementing a feed budget.
Energy requirements for ewes steadily increase during late pregnancy and this means energy provided by feed needs to rise to meet that demand.
Supplementary feed levels for a twin bearing ewe are 25 per cent higher than a single bearing ewe and these animals should be managed separately.
This highlights the importance of pregnancy scanning and splitting mobs for grazing.
If scanning is not undertaken, producers can consider the average percentage of twin bearing ewes in their mob and decide whether to feed for twins or singles.
Health issues, such as high worm burdens and early onset of acidosis, will also reduce ewe feed intake.
Ewes may suddenly stop eating for various reasons, including changing from one type of supplement feed to another, adverse weather, prolonged handling in the yards, walking long distances, damage to the liver by a toxin, gut problems or clinical acidosis.
For more information on how much to feed pregnant ewes during the winter months go to www.lifetimewool.com.au, speak to a livestock advisor or contact your local Department of Agriculture and Food office.
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