Condition scoring is a useful tool in any sheep breeding enterprise to assess how a mature group of animals are tracking at a point in time during the year.
Unfortunately, as easy as it would be, weight can’t be used to assess where ewes are at, as weight varies considerably with frame size and mature sheep weights can vary substantially for the same condition score. Condition score measures the body reserves of a mature sheep by looking at the tissue and fat cover over the loin area. It is the most accurate way to measure the body condition of the flock – especially as it’s changing over time and as ewes are going through pregnancy and getting closer to lambing.
To assess a condition score average within a mob you will need to look at a minimum of 50 ewes. This will give you a score which will well represent the mob. They are best scored when they are relaxed, as tense animals are difficult to get an accurate score on.
During pregnancy, condition score is the most accurate way to assess if the nutrition being provided from pasture or supplementary feed is adequate to support the pregnancy status (twin or single) and gestation stage of the ewe. By regularly assessing condition score you will identify early if nutrition is inadequate, and you can move paddocks or modify rations before it’s too late.
Especially on supplementary feed, in containment pens or when ewes are being run in very large mobs, you can find a ‘tail’ emerging in the mob which may be up to half a condition score under the average condition score of the mob. If you monitor the spread of condition score within a mob, you will easily be able to identify this as it occurs. If this is the case, it’s worth drafting off this tail and separating them into a different pen or paddock so they can be given access to better pasture or extra supplementary feed if required.
Monitoring condition score and ensuring ewes hit targets prior to lambing has a large influence on lamb birth size. Targets are slightly different for merinos and maternal ewes and can vary also depending on time of year of lambing. Generally, in merino’s we aim for around CS 3 for a single bearing ewe and CS 3.5 for a twin bearing ewe and slightly less for maternal ewes.
As the ewe condition score decreases below targets – lamb birth weight is likely to be reduced which will have a major impact on the ability of the lamb to survive. Particularly in twin bearing ewes if they have a condition score well below 3.5, the twin lambs will have a very low chance of surviving as they will be well below birth weight targets. This means they’ll have reduced body fat to withstand weather and reduced brown fat which acts as the first energy reserves to allow the lamb to stand up and get its first drink.
If ewes are well above condition score targets, they are often not fit enough to lamb successfully and can be prone to metabolic disorders. Lambs can also be at high risk of being a large birth weight which can often lead to Dystocia. Dystocia is the most common cause of lamb death as it will often cause brain damage or nervous system damage associated with the difficult birth meaning the lambs will be unable to survive. Dystocia is also linked to a higher percentage of ewe mortality as it also impact the ewe and the birthing process.
Planning ahead to set condition score targets and ensure appropriate nutrition throughout pregnancy will give you the best chance of achieving a successful lambing result. Regularly monitoring condition score and adjusting ewe nutrition will reduce ewe mortality around lambing and allow lambs to hit birth weight targets to achieve higher survivability and therefore better lamb marking rates.
Deb Scammell, Talking Livestock
Published in Stock Journal May 2022
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