Proper feeding makes for fewer lambing problems

Andrew Kinsella

Close to 70pc of lamb foetal growth occurs during the last six weeks of pregnancy. In fact, the weight of each foetus increases by nearly 2kg during the last three weeks of pregnancy. Milk-producing alveolar cells in the ewe's udder also develop during this period along with colostrum and its antibodies.

It is also during this period that the lamb lays down fat around its kidneys, often referred to as brown fat. This fat has the ability to produce large amounts of heat very rapidly and plays an important part in the survival of newborn lambs, particularly providing energy between birth and first feed.

As a result, there is a massive increase in the ewe's energy and protein requirements. Complicating the issue further is the fact that as the lambs grow within the ewe, they occupy more space and this can restrict the ewe's intake by 25-30pc.

Thus, it is easy to understand why it is necessary to provide high-energy concentrate supplementation during late pregnancy. Insufficient supplementation can result in decreased lamb birth-weight, insufficient colostrum and increased incidences of conditions such as vaginal prolapse and twin lamb disease (pregnancy toxaemia).

On the other hand, acidosis can result from feeding too much concentrates or where the concentrate results in rapid fermentation within the rumen.

Rapid fermentation, particularly where cereals have been finely ground, reduces the growth of bacteria that digest fibre. This leads to a fall in roughage intake and poor rumination. The concentrate becomes a substitute for roughage rather than a supplement. The tendency by some meal compounders to grind cereals rather than just break the grain is detrimental to good sheep nutrition. On the practical side, once feeding levels exceed 0.5kg/day, the animals should be fed twice daily.

Check ewe condition three to four weeks pre-lambing (this can easily be done when administering the pre-lambing clostridial booster) and adjust feed level accordingly.

Be careful with ewes carrying singles as high feed levels at this stage can result in oversized lambs. Take particular note of the first ewes that lamb. Do they have an ample supply of free-flowing colostrum? Adjusting feed/protein levels can rectify a low colostrum problem within a three or four-day period.

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Roughage needs to be in front of the ewes at all times. The notion by some farmers of restricting roughage in order to reduce the incidences of prolapse does not stand up to scrutiny. In fact, it may aggravate the problem and does nothing for proper rumen function.

Where ewes do prolapse, harnesses are highly effective and simple to use. In my opinion the insertion of plastic 'spoon' retainers and stitching should be avoided, if for no other reason but animal welfare.

Rations should be properly balanced with minerals and vitamins. I have come across situations where ewes have 'gone down' before lambing because there was insufficient calcium in the diet.

I have also come across situations where ewes have 'gone down' after lambing because there was too much calcium in the pre-lambing ration. The reason for this is that when there are high levels of calcium circulating in the blood the pathways for calcium mobilisation from the bone become dormant and it takes some time for these systems to reactivate again when calcium blood levels fall. Likewise with trace minerals and vitamins. There is research to show that lambs born from cobalt-deficient ewes are slower to start sucking. Selenium deficiency may lower resistance to cold stress and iodine deficiency may reduce lamb heat production.

Some farmers believe that incorporating high levels of magnesium (such as cal-mag) in the ration before lambing helps to prevent grass tetany. This practice cannot be advised as it will do nothing for tetany prevention and high levels of magnesium before lambing may result in ewes going off ration and resulting in other conditions such as twin lamb disease.

Undernourished ewes, particularly younger ewes, often exhibit poorer maternal care and often abandon their lambs. This is generally seen at let-out to pasture where the ewe will scurry to graze and at least one lamb (the weakest) will be mis-mothered. Thin ewes have no tissue reserves to milk 'off their backs'. If there is insufficient grass, there is no option but to feed such ewes concentrates after let-out.

I would also suggest that such ewes, particularly those with twins, should be let out in small groups, into a small paddock and only moved on when there is confidence that both lambs are being cared for.

Andrew Kinsella is a sheep farmer from Rathdrum, Co Wicklow. He is a former sheep specialist with Teagasc

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