7 February 1997


By Emma Penny

FOR producers with May lambing flocks, early February coincides with the start of placental growth in pregnant ewes. This is the time to assess ewe body condition and review feed requirements for the remainder of the winter period.

Thats according to Linda Mitchell, sheep specialist at the Scottish Agricultural College, Aberdeen.

She explains that during the second and third months of pregnancy the placenta fully develops while the foetus only reaches around 15% of final birthweight. Because placental growth does not greatly increase ewe nutrient requirements above maintenance, she suggests that any necessary changes in ewe body condition should be made at this time.

"For ewes in good condition – score 3-3.5 – a loss of up to half a unit body condition score is acceptable. There is evidence that a small weight loss will stimulate placental growth but this effect is not seen in thin ewes of below 2.5."

Weather during February can often be extreme and, without proper supplementation, wet cold conditions cause rapid mobilisation of ewe body reserves, says Dr Mitchell. "Little or no grazing is usually available at this time and ewes are almost entirely dependent on supplementary feeding for their nutrition."

For fit ewes, she suggests that supplementing with moderate to good quality hay or silage alone should be adequate. Thin ewes should be given extra energy in the form of cereal or sugar beet pulp – up to 400g/ewe/day – to ensure that placental growth is not compromised and body reserves are built up for lambing.

Dr Mitchell also suggests that where possible wintering fields should provide some natural shelter to minimize the effects of bad weather. Alternatively producers could consider in-wintering. "In-wintering reduces poaching damage to pasture, increasing the amount of herbage available to ewes during late pregnancy. Ewes may also be winter shorn, avoiding the need ot shear ewes with young lambs at foot."

However, she admits that most producers choose to lamb in May because it is a low-cost system which does not usually require housing. "Housing will add to costs and complexity," she says. Where ewes are in-wintered, the shed should provide adequate ventilation and access to forage. "Ad lib hay or silage is ideal. However, pit silage may be too good, and should be restricted or mixed with straw to avoid ewes gaining too much weight in mid-pregnancy."

Whether ewes are in or out-wintered it is vital that pasture is set aside for late pregnancy. "Fields should be chosen in the early new year, stock excluded and a spring fertiliser dressing applied to stimulate grass growth."n

SACs Linda Mitchell – May lambing ewes will need supplementing with moderate to good quality hay or silage.


&#8226 Ewes lose no more than half body condition score unit.

&#8226 Ensure thin ewes receive extra energy.

&#8226 Choose fields with some natural shelter.

&#8226 Consider in-wintering.

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