16 August 2002

Cost benefits a vital factor

Comparing the cost benefit

of feeds is crucial to ensure

that cheap by-products dont

end up being an expensive

part of winter rations.

Richard Allison reports

PROCESSING by-products and opportunist feeds can have an important role in keeping winter ration costs low and maintaining milk quality, providing they are used with care.

Carrots, potato hopper feed and fresh citrus can be cost-effective ingredients in carefully balanced winter rations, says Kite Consultings East Anglia-based nutritionist Ben Watts. "But each feed has its own set of rules for storage and feeding to maintain cow performance."

Fresh citrus pulp has a metabolisable energy content of 12.6MJ/kg of dry matter and is a good source of digestible fibre. But inclusion must not exceed 7kg a cow daily to avoid tainting milk.

Herd manager Greg Bird has successfully included citrus pulp in the milking ration for the Lavenham herd at Leaden Hall Farm, Essex, at up to 5kg a head. The 235-cow herd is averaging 9300 litres.

"It was included as a source of digestible fibre to maintain milk fat at 3.7%. The ration also contained maize silage, grass silage, brewers grains, rolled wheat and a protein blend."

Cows find citrus pulp palatable, but Mr Bird says it must be left for about 3-5 days after delivery before use. Cows do not eat it as readily when fresh. "I also specify when ordering that each load is mostly orange pulp as cows find grapefruit and lemon pulp unpalatable."

Despite fresh citrus being a farm assured feed and the factory having magnets to remove metal objects, Mr Watts ensures clients check each load before feeding to ensure that it is up to specification and free from contaminants. "Ensure you purchase from an accredited source," he adds.

At £12/t, feeding fresh citrus pulp is cost effective and it is widely available from a fruit juice factory in London. This equates to a cost of 0.38p/MJ of energy, which is similar to fresh grass at 0.42p/MJ.

Mr Bird also feeds brewers grains from a local brewery. "In addition to the weekly delivery, about 200t is clamped with potatoes in summer. This will be used after Christmas when prices often rise."

Ration mixing time is critical when feeding wet by-products, as over mixing results in a heavy stodgy ration, which rapidly deteriorates in the trough. "We have found that a mixing time of seven minutes is ideal. In addition, straights and citrus pulp go into the feeder wagon first, followed by grass then maize silage to maintain ration structure."

Good storage is crucial, as half of the cost benefit of cheap feed can be lost when stored incorrectly, says Mr Watts. "Citrus pulp stores well outside in a clamp, but other feeds such as potato hopper which are wetter, tend to store less well.

"Potato hopper feed consists of uncooked chipped potatoes, but specify a low oil content when ordering." Last year, it was included in summer rations at 8kg a head.

High oil versions have a typical oil content of about 20%, which can reduce butterfat. "To minimise this problem, only feed up to 6kg a head, while the lower oil potato feed can be fed safely at between 8-15kg a head."

The wet nature of potato products, with a dry matter content of 20%, means that rations can quickly become too wet, says Mr Bird. But when the ration is dry, wet by-products can help improve ration structure and intake.

One advantage of using potato hopper instead of stock potatoes, is that it is already chopped, so cows cannot select them out so easily, says Mr Watts. Cow selection is a common problem when feeding carrots and potatoes in a ration mix.

"Ensure rations are well mixed and pushed up to the feed barrier as cows will push it away when rooting for roots and tubers."

While opportunist feeds can be cheap, their use must be weighed against the consequences of changing rations. These feeds are often available in small amounts, which can lead to excess chopping and changing of the ration. "Consistency is important when maintaining milk output and quality, so ensure you have a regular and reliable supply."

To assess whether a by-product feed is cost-effective, Mr Watts uses the relative feed value approach. "Feeds are ranked on a value for money basis to identify their true cost based on energy or protein content.

"Producers can keep ration costs under control using this approach. Some by-products may seem cheap on a £/t basis, but are an expensive feed. Some feeds such as bread waste can vary greatly in dry matter content from load to load affecting its true cost."

"Break-even costs can also be calculated. Potatoes would have to fall to £12.25/t before being cost-effective compared with potato waste at £12.50/t on an energy basis," he adds. &#42

Typical relative energy values

£/t p/MJ

ME

Fresh citrus pulp 12 0.38

Grazed grass 8 0.42

Rolled wheat 65 0.56

Brewers grains 19.50 0.69

Maize silage 25 0.76

Dairy compound 106 0.92