Feed maize with care to keep ewes healthy
Feed maize with care to keep ewes healthy
Maize silage can be a
valuable forage providing
energy to complement the
high protein of grass silage.
But without careful feeding,
ewes on maize can become
fat and prone to metabolic
disorders in late pregnancy,
such as twin lamb disease.
Simon Wragg reports
FEEDING a mix of maize and grass silage to ewes in late pregnancy has been approached with caution on one Worcestershire farm.
John Adams produces good quality grass silage at 70 D-value each year at his Old Manor House, Bockleton, near Tenbury Wells, to feed 400 Mule ewes during winter and pre-lambing.
Until two years ago, he considered maize expensive to grow, but calculations on the 166ha (410-acre) farm show both silages have similar costs of £9.80/t freshweight, based on two cuts of grass and when maize is eligible for arable area aid.
"I had heard from other producers that maize increased forage intake when fed with grass silage and that has happened here. But there is a tendency for some ewes to gorge on it."
With his ADAS sheep consultant, Kate Phillips, Mr Adams formulated a diet based on a 50:50 grass/maize silage ration supplemented with a 20% protein home-mix concentrate.
A total of 13kg a ewe home mix ration is fed in gradually increasing amounts from 0.25kg-0.40kg in the four weeks before lambing. Mineral supplements are also fed.
Little difference in concentrate levels is made for ewes carrying multiples, as the flock consistently achieves lamb crops of 180%. But before any ration can be formulated, Mrs Phillips says producers must remember the critical require-ment when feeding mixed silage is to balance the low protein of maize, typically 7%, against the higher level of grass silage, typically 14%, with brought in protein sources such as soya, groundnut or rapemeal.
At Old Manor House, a daily supplement of 10g a ewe of soya at 44% protein is fed as part of the home-mix concentrate, in addition to the ad lib silage, to ewes grouped according to condition score before housing.
"The danger of feeding late-pregnancy ewes maize silage low in protein is that it can reduce colostrum and milk production – the lambs natural defences," says Mrs Phillips. She urges all producers to analyse silage to determine what level of protein is needed.
But maize needs no extra energy, for its high starch level provides plenty rumen fermentable energy. This gives a synergistic effect with the high protein of grass silage.
As a result, the level of concentrate fed in addition to maize/grass silage should be lower than for grass silage only rations.
To find the level of concentrate needed, Mrs Phillips urges producers to take a hands-on approach when condition scoring ewes: "Feel for back-fat rather than visually scoring ewes – winter fleeces can be very deceptive."
At Old Manor House the flock is divided into thin, fit and fat ewe groups for housing four weeks before lambing. Fat ewes have concentrates reduced to about 0.25kg a ewe a day and substituted with straw. Thin ewes receive extra concentrate up to 0.40kg a ewe a day to improve body condition.
Feeding 50:50 silage mix to all ewe groups proves efficient, says Mr Adams. "They clear the troughs every time." But he has found that the odd ewe that will gorge on maize silage, so he will cut its inclusion from 50% to 33%.
Because the ewes do so well on the maize/grass silage, he has also decided to reduce the protein in the home-mix from 20% to 18% to keep a check on ewe condition.
"Ewes do well on maize, but it does mean I have to watch out for those which are steaming ahead and putting on too much condition as lambing approaches."
As a consequence, feed barrier space a ewe must be sufficient to avoid cramming, which increases stress and may lead to abortion in extreme conditions. Mr Adams will split the ewe pens next year to increase feed barrier space.
As pressure on sheep margins looks unlikely to relax, he will look to cut concentrate costs to maintain margins rather than rule out maize.
"It fits our system and it feeds well. The other advantage with maize is it reduces grazing pressure on turnout paddocks in the spring." *
John Adams will cut back on the inclusion of maize to keep a tight check on ewe condition.
Ewes are split into thin, fit and fat groups by condition score before housing.
MAIZE/GRASS SILAGE TIPS
• Analyse and supplement with protein.
• Monitor condition of ewes.
• Reduce concentrates with straw if ewes too fit.
• Feed mineral supplement.