Fulfilling domestic demand for protein feed

Despite growing demand from UK livestock producers for locally-sourced protein feedstock, about 60 per cent of protein crops used for animal feed are imported, largely because of the difficulty in growing consistently high yielding legumes in some parts of the UK, according to Dr Robin Walker, a researcher at Scotland’s Rural College.

Of the 2.6 million tonnes of protein-based animal feed used annually in the UK, about 37 per cent derives from home-grown cereals and 3 per cent from home-grown pulses. The remainder comes from imported maize (5 per cent) and soya (55 per cent), according to 2016 Defra figures.

With a current value of £375 per tonne plus transport costs, importing soya can be expensive, but its high crude protein content of about 45 per cent makes it a valued feed component for many farmers.

But should the UK not be looking to better fulfil its own protein demand? David Rhodes, technical manager for DLF Seeds says: “Imported soyameal still holds a monopoly as the highest protein content feed, but it is expensive, and new plant breeding techniques mean home-grown legumes can now really hold their own.

They have been specially bred to be high in protein and valuable minerals, while also being easier to grow than their predecessors through improved vigour and disease resistance. As legumes, they will also contribute to soil nitrogen for the following crop.

“Being able to grow protein yourself also increases farm self-sufficiency and provides some protection from fluctuating market prices for protein substitutes.”

According to Dr Walker, the main barrier to increasing the production of home-grown proteins is the inconsistent yield and quality which is associated with many legumes, particularly in northern England and Scotland where demand for livestock feed is high.

“Peas and beans are the main protein crops grown in northern England and Scotland, but some farmers are put off growing these crops because of the difficulty in getting them established in cold soils. They can also suffer badly from frost damage, they are vulnerable to lodging and can be difficult to harvest.”

He believes intercropping could be a potential solution.“SRUC trial work from the 2016 and 2017 seasons showed how intercropping cereals with grain legumes in spring can lead to more reliable production of high protein feed, particularly in north of the UK.”

As part of the trial which took place in Aberdeenshire, the following intercrops were sown and compared to legume monocrops:

• Lentils (80 per cent), oats (20 per cent)
• Peas (60 per cent), barley (40 per cent)
• Lupins (60 per cent), barley (40 per cent)
• Field beans (60 per cent), barley (40 per cent)

In most cases, the presence of the cereal boosted the yield of the legume and vice versa. In some cases the effect was quite dramatic.

Dr Walker says: “In year two of the experiment, our plot of just peas failed completely. But where the peas were grown alongside Westminster barley, they produced about 1.2t/hectare of dry matter and the barley produced about 1.6t/ha of dry matter.”

Similarly, the lupins failed to establish when grown independently, but established successfully when grown alongside barley. The only instance when intercropping had a negative effect was when the beans were grown with barley.

“This was a result of barley shedding its seed,” says Dr Walker.

“In most cases, the higher yield of the legume associated with intercropping led to a higher nitrogen output per hectare than legumes which were grown on their own, although there were some exceptions when the cereal overwhelmed the legume.”

Although it is not entirely clear how the presence of the cereals led to improved legume performance, researchers suspect the cereals helped prevent the spread of disease between legumes and, in some cases, prevented the legume crop from lodging.

The research team also sowed four different varieties of soya to assess the potential of growing the crop in northern regions of the UK, but both years the soya failed to establish.

“After it failed the first year, we grew it with a fleece the second year but it did not make any difference. There is still a long way to go before we have a variety which is compatible with cold northerly weather,” says Dr Walker.