Pros and cons of feeding a home-grown dairy ration

Producing a home-grown ration for cattle is an aspiration for more and more livestock farmers, and many rearing and finishing beef have made good progress in this endeavour.

But dairy herds present more of a challenge, and where milk yields are high, there is a perception that imported soya in particular is difficult to ditch.

See also: How three dairy farmers maintain high-yielding herds

However, as international feed markets become increasingly volatile and issues such as deforestation and sustainability call the inclusion of soya into question, its use is being cut, even in milking rations.

Finding home-grown – or at least UK-produced – alternatives requires a multi-pronged approach.

Replacing the essential amino acids and the rumen-bypass protein, which are features of soya, only add to the challenge.

Experts agree this requires a whole-ration approach rather than a one-for-one substitution, and say the first place to look is forage.

Increasing forage protein

Growing lucerne can be a good start, but this high-protein forage requires light soils and shelter and can present challenges in weed control.

Instead, attention for many should turn to upgrading grass swards.

Independent grassland consultant Dr George Fisher says adding red or white clover would “generally be my first option and can boost crude protein [CP] in forage from, say, 15% to 18-20%”.

“This increase doesn’t sound much, but there’s a higher proportion of true protein and less non-protein nitrogen in this CP figure than in a pure grass sward.”

However, much of the protein in grass-clover swards is highly rumen degradable protein (RDP).

This means high-yielding cows will need a digestible undegradable protein (DUP) or rumen-bypass source if they are substituting soya.

Growing beans as a concentrate

Independent silage consultant Dr Dave Davies says beans are an obvious choice.

However, he urges those growing legumes not to opt for wholecrop in high-yielding dairy diets.

“If you wholecrop beans, you are diluting the benefit of the [high protein] pulse, while also producing a low-digestibility, high-fibre forage, which will limit intakes,” he says.

Instead, he advises growing beans as a concentrate, although the jury is out on the best way to process them.

Trials, including crimping and rolling high-moisture beans, as well as dehulling and toasting, are under way as part of the Nitrogen Efficient Plants for Climate Smart Arable Cropping Systems (NCS) project. 

Funded by Defra, it aims to increase the acreage of pulses to 20% of arable land across the UK.

Dave suggests that crimping, which involves ensiling beans in a clamp or bag in anaerobic conditions, is best done as a bicrop with peas, as these help fill the air spaces between the larger beans.

Through the project, he has already analysed mixed pea/bean crops at about 30% protein in the dry matter (DM) when crimped.

Early indications are that dehulling/toasting may have the favourable effect of increasing DUP, which is lower in beans than in soya.

Dehulling/toasting, micronising (by a feed processor), or cutting early for on-farm crimping may also have the scope to reduce the anti-nutritional factors – notably tannins – often cited as placing limits on the inclusion of beans in rations.

However, independent nutritionist Diana Allen says concerns about tannins are overblown, and she has no hesitation in feeding up to 5kg a head a day of beans.

Protein in whole beans, at about 29%, compares poorly with Hi-pro soya, at 46-55%. This means about twice the weight of beans should be fed for the same intake of protein.

But starch content is substantially higher, at about 40%, compared with 5% in soya, opening the way to reduce ingredients higher in starch, such as cereals.

© Ann Hardy

Soya versus non-soya ration

Such a ration has been compiled by Scotland’s Rural College (see “Scotland’s Rural College ration”).

Since beans contain around one-third the methionine of soya, supplementation of this essential amino acid may be required if beans are the sole protein source.

While beans as a sole protein might be considered for low-yielding herds, Diana does not recommend this beyond average production of 8,500 litres.

Furthermore, because beans are high in RDP, she says the nitrogen and energy in the ration must be carefully balanced to maximise rumen function and the production of microbial protein.

For higher yielding herds, she suggests a good UK-grown complement for beans would be protected rapemeal.

This will not only lift DUP but also methionine content.

Cost

Costing a ration containing home-grown beans (or other legumes) is not straightforward as a wide range of growing costs are reported, and the crop’s agronomic benefits are difficult to measure.

If the two rations are costed at purchase prices (beans at £213/t plus £15/t for rolling, high-protein soya at £345/t, barley at £156/t plus £15/t for rolling, and protected rapeseed meal at £345/t), there is a 5p-a-cow-a-day benefit to the bean ration.

For a 200-cow herd, this equates to £10/day, or £2,000 over a 200-day winter.

However, when compared using the variable cost of growing beans at £150/t (Nix Farm Pocketbook), plus £15/t for rolling, that benefit increases to 33p a cow a day, or £66/day, and £13,200 for 200 cows over winter.

Carbon footprint

Inconsistent yields are sometimes cited by farmers as a reason not to grow beans.

In their favour, they fix nitrogen, improve soil structure, can make an excellent break crop, and give average yields of about 5t/ha.

The crop’s sustainability credentials are affirmed by Farm Carbon Toolkit, which has calculated the carbon footprint of the two rations (see “Nutrient analysis of example ration” table).

This weighs in at 0.929kg carbon dioxide equivalent (CO2e)/kg of feed for the soya-based ration and 0.770kg CO2e for the beans-based ration (not including transport to the farm).

Somerset herd combines high milk output with home-grown feeds

Ollie Blackburn © Ann Hardy

Somerset farm manager Ollie Blackburn is driving a policy of home-grown feeds for the 350-cow dairy herd he runs at Dillington Farms, near Ilminster.

High annual milk production adds to this challenge, with an average of almost 12,000 litres demanding careful formulation and a nutrient-dense ration.

Sustainability is at the heart of the business ambition and has seen a shift in the 800ha (1,977-acre) arable operation towards increasing protein in forage, bicropping and adding legumes to the rotation.

A particular feature has been 15m herbal ley strips, (grown under Mid Tier Stewardship), which now form a boundary on all sides of every arable field.

With no arable headland and no turning on crops, this has led to a lift in performance of 1.6-2t/ha for crops such as winter wheat or maize.

The herbal leys are cut for silage after flowering and fed to all classes of stock.

A small quantity is included in the milking ration (see “Dillington Farms milking ration”), although this depends on composition, which is variable.

However, this has reached 12.8% crude protein and 11.1 MJ metabolisable energy/kg dry matter.

Home-grown pulses

Pulses form the mainstay of the home-grown ingredients and – together with a 50:50 mix of rapeseed meal and protected rapeseed meal – have allowed soya to be removed from the milking herd’s partial mixed ration.

And there is a further ambition to reduce the 7kg a cow a day of bought-in concentrate fed in the robots.

Beans are now part of the farm’s rotation and are treated with a grain preservative, costed at £98/t and used in the milkers’ ration.

Bicropped peas and barley (14.8% protein, 42% starch) have also been preserved with Propcorn as a concentrate feed and have displaced 2kg of purchased concentrate in weaned heifers’ feed.

With legumes said to provide an excellent entry for rye or grass, and the pea/barley bicrop providing a means of exiting grass without ploughing, Ollie says the process is helping to create a circular, self-sustaining system.

“We are on a journey,” he says. “We want a stable and sustainable farming business that is resilient to external change, and the whole team is enjoying experimenting with different feeds.”