Straw to satisfy lowland sheep
By Michael Gaisford
HAY and silage are not the only winter feed forage options for lowland sheep flocks.
Winter feeding systems based on straw can also be successfully employed, as developed at ADAS Rosemaund, and detailed at the World Sheep and Wool Congress.
The straw feeding system was developed particularly for arable farms with sheep, allowing them to keep more ewes on the grassland area of the farm or release it for growing more cash crops and to provide an environmentally friendly way of disposing of surplus straw.
"Our objective was to develop a biologically efficient, economically attractive system for lowland mixed farms," explains project leader Mervyn Davies.
"The approach taken was to investigate component parts of a straw-based system in nine projects encompassing 26 experiments over seven years.
"This has culminated in a highly successful lowland sheep system based on sound scientific principles" says Mr Davies.
The initial work at Rosemaund with March-lambing North Country Mules evaluated different types of straw for feeding to housed ewes in the last two months of pregnancy. It came to four main conclusions which are listed in the panel opposite.
Mr Davies says that because feeding large amounts of cereal-based supplements in late pregnancy can lead to metabolic disorders, flat rate feeding of the compound supplement was evaluated and the level and type of protein supplement also investigated. Main conclusions from this research work suggested that:
• Feeding a compound at a flat rate of 845g a ewe a day was best.
• Flat rate feeding simplified flock management.
• Blood tests on ewes confirmed that energy status of the diet was satisfactory.
• There is no advantage in late pregnancy in feeding with straw a supplement containing more than 16% crude protein.
The project examined several alternative supplements to the standard mix of 80% whole grain barley and 20% soya bean meal. Three conclusions reached from this work were:
• Whole-grain wheat can safely substitute for whole barley, and contribute similar energy levels.
• Chopped fodder beet can provide up to two thirds of the dry matter intake, and satisfy energy requirements.
• Feeding a pelleted compound on the floor may be a viable option.
Where a switch is made to this straw-based winter feeding system, grass silage is not made, and there are no aftermaths for sheep to graze, a change in the summer grazing programme will be necessary.
At ADAS Rosemaund it has been found possible to increase stocking densities at grass to 30 ewes a hectare (12/acre) by offering a creep feed containing a coccidiostat to lambs reaching slaughter weights by August.
"This concept has had a wide uptake in the drier, eastern counties of England, where there is competition for grass between ewes and lambs from mid-summer onwards," says Mr Davies.
"Our results have also shown that increasing the stocking rate has led to increased output a hectare and increased gross margins," he says.
• Ammonia-treated straw doubles straw costs and is not economic.
• Untreated barley straw is the preferred option but wheat straw can be used.
• Straw should be fed ad-lib, allowing about 1.5 kg a day for a 70 kg ewe.
• Performance will be satisfactory if compound supplementation is adequate.
Straw-based winter feeding systems for sheep allow lowland mixed units to release more grass for grazing and make use of surplus straw.