Fit ewes can be as susceptible to twin lamb disease (aka pregnancy toxaemia) as thin ewes although the prevention is slightly different.
Remember, twin lamb disease is a result of lack of energy to meet the demands of the growing foetus(es) and the risk period is three to four weeks pre-lambing. The rumen volume of overfat ewes may be restricted due to the excess fat in the abdomen taking up space. On paper, it may look like the energy needs are being met but they may not be able to consume enough. This puts greater emphasis on trying to keep them from getting too fat during the winter – only achievable with regular condition scoring and putting fat ewes onto less grass than the others. Consider scenarios that would encourage more exercise – bigger, sloping fields, for example.
Targeted nutrition by using the scan results and raddle marks all helps to ensure they get what they specifically need and no more. If they are on bulky feeds such as low energy forage or low dry matter root crops, they are going to be less likely to eat enough – consider restricting these bulky feeds in favour of energy dense alternatives such as high quality silage or hard feeds as they approach lambing.
Too much starchy feeds (e.g. crushed barley, wheat-feed) however, reduces rumen pH which leads to less energy digestion from the forage. Another reason for targeted feeding according to the scan result and predicted lambing date. Feeding twice-a-day, particularly when the feed requirement exceeds 0.45kg/day, will reduce this effect. If possible, use high energy, low starch feeds such as sugar beet pulp, oats, or whole barley. Look out for low quality ingredients in ewe rolls such as oatfeed or sunflower meal – if these are high up in the list of inclusion then the energy value of the roll will be low, they will need to be fed at higher levels which will have a greater impact on rumen pH.
As they grow bigger, feeding space becomes more of an issue. The guidelines for trough feeding is 45 cm per ewe – this will stop the greedy ones eating much more than they need and the shy ones eating less. Check silage intakes – the forage may look good on paper but if they don’t eat it then it is not providing much energy. Get metabolic blood tests done by a vet three to four weeks pre-lambing to check whether energy is low. If so, this gives opportunity to provide more energy and reduce risk. If worried, you may want to consider putting out liquid molasses as an insurance.
Be prepared for problem cases, particularly if the ewes are fatter (or thinner!) than they should be. Have some twin lamb drench or glucose solution in stock. For rapid identification look for ewes hanging back at feeding times, unusual postures such as kneeling with hind legs pointing forwards, stagging with heads pointing to the sky, teeth grinding, twitching, appearing to be blind or sickly sweat smelling breath. Seek veterinary diagnosis to confirm as it is easily confused with hypocalcaemia (lambing sickness), listeriosis and pneumonia. If cases start to arise, check energy in the ration in the first instance, you want to minimise the number of ewes in the flock affected. Treatment via injection or drenching will be required for those diagnosed with the condition, but cure is not often successful – as the adage goes, prevention is better, which is certainly true in this instance.
Poppy Frater, email@example.com
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