Much attention is paid to feeding the ewe in the run-up to tupping time, but Alison Bond of Rumenco points out that offering an adequate diet during pregnancy is equally as important.
While in the past it has been acceptable to allow a pregnant ewe to lose some condition during pregnancy, the latest research suggests otherwise, says Dr Bond.
“The lamb is fed by the ewe via the placenta and therefore the ewe’s nutritional demands must be met, if her offspring is to develop to its full potential and perform to expectations in later life,” she says.
“Studies have indicated that nutrition during pregnancy should be given greater attention. However, it can be challenging to maintain ewe condition over the winter, especially if the flock is sent away to graze elsewhere. Nevertheless, provision must be made to provide access to good quality forage, as well as supplementary feed, where necessary.
“Ideally, the target body condition score at tupping should be maintained throughout pregnancy. If a compound feed is offered, it must be used sparingly or the ewe may put on too much weight and that can cause problems at lambing time.”
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Poor grass growth due to the drought conditions during last year’s grazing season was thought to be at least partially responsible for the decline in average lamb numbers in autumn 2022, she says.
“If this situation is repeated, I would recommend supplementing the ewes’ diet with haylage. The other alternative is to put out energy feed blocks, which will encourage the population of healthy bugs in the rumen and will also contain minerals and vitamins that may be deficient in the grazed grass.
"The density of the block will regulate the amount that individuals will eat and in most situations, one block should be provided per 30-35 ewes. A molassed product will be attractive to the ewes and will help to promote intakes.”
Block feed products that contain salt should be sited away from water sources, she stresses.
“This will help to regulate intakes, as the salt will encourage the ewes to seek water and move away from the block at intervals. Conversely, if intakes are too low, the blocks can be moved closer to a source of water.
“Some blocks are supplied without a container and to reduce waste they should be placed in a bucket, to prevent the contents from being trampled and becoming contaminated. If a plastic bucket is used for this purpose it should have drainage holes, or a tyre can be used as an alternative.
“Additional vitamin mineral supplements should not be required if key nutrients are included in the block ingredients and a switch can be made to a high-energy product as lambing time approaches. Specialist blocks are available for ewes turned out on rough grazing and these contain urea protein, which helps to encourage the development of healthy rumen bugs; they can also be useful for finishing lambs.”
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Sheep will usually consume adequate levels of copper from grazing and supplementation of the trace element is not recommended for certain breeds including the Texel, which can suffer from copper toxicity, she says. However, deficiencies of other trace elements are fairly common among UK flocks.
“Selenium and cobalt deficiencies can have a negative effect on performance. The testing of both grazing and forages has highlighted widespread selenium deficiency, so it is worth considering supplementation because it is important for system function and the maintenance of good health. Cobalt is required to support the immune system and it is often lacking in summer grazing," says Dr Bond.
“Another vital trace element is zinc, which is important for a range of functions, including internal and external tissue maintenance, as well as foot, udder and gut health. Our forage mineral testing programme has recently shown up some borderline zinc deficiencies, so supplements should be provided if it is found to be lacking."
Dr Bond says that forage mineral testing is preferable to relying on soil analyses to help decide on whether ewes will need nutritional supplementation in pregnancy and identify any minerals that may be deficient in the diet.
“There is no direct relationship between the minerals that are present in the soil and those, which are found in grazed grass or silage. We have seen fairly wide fluctuations in forage analyses over the past few years.
“I think that producers may be missing a trick, when it comes to paying attention to detail in the feeding of pregnant ewes. Unborn lambs rely on gaining all their nutritional requirements through the ewe’s placenta at a time when vital organs are developing and growing.
Their future performance will depend on having access to all the nutrients that are required to ensure that they grow strongly and achieve target growth rates and, where appropriate, provide future flock replacements,” concludes Dr Bond.
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