21 November 1997

MAKING WISE CHOICE

How can you ensure you are

getting value for money with

a silage additive?

Jessica Buss took a

researcher on-farm to find

out how to make the best

silage additive choice

BEFORE choosing next years silage additive, first decide whether last years one worked – and when it has not worked ask why.

So advises Leeds University researcher Mike Wilkinson, who suggests examining the open silage face to check the effect of an additive.

"A good silage should not feel slimy, and should not smell fruity or butyric," says Dr Wilkinson. "When a silage falls down on these aspects consider what you were asking of it."

Phil Lannigan, farm manager at West Broughton Farm, Sudbury, Derbyshire, used an inoculant on the last few acres of this years second-cut silage made in wet weather after a machinery breakdown.

The additive had not benefited some parts of the crop in his clamp – those made from old permanent pasture with a low sugar content.

Dr Wilkinson says an acid or no additive may have given a more economic response than the inoculant used.

Luckily, the poor material was only a small proportion of Mr Lannigans total silage crop – with 30ha (75 acres) of first- and 20ha (50 acres) of second-cut clamped, and 5ha (12 acres) of maize. The 100-cow milking herd plus 100 followers averages 6300 litres with 3800 litres from forage.

Dr Wilkinson advises producers to question why they are using an additive. "A lot of additive is put on without much thought as to why it is being used."

He cites two reasons to use an additive: To overcome an unsatisfactory situation, such as poor grass varieties, or to make a good silage better.

To solve a specific problem, choose an additive with a good track record when being used in circumstances similar to those on your farm. For example, when maize is at risk of moulding, and producing toxins which will depress intake, choose an additive that prevents moulding. When silage must be made of wet grass or poor grass varieties, choose an acid.

But in Mr Lannigans situation, which was to make a potentially good silage better by controlling fermentation, an inoculant should give the best response, especially when the grass is above 25% dry matter, says Dr Wilkinson. Some inoculants have also been proven to reduce protein breakdown in silage.

"Additive use should depend on how much you rely on it in the ration. When silage is a small proportion of the diet, it is easier to overcome poor palatability with supplements and other forages," he says.

But when relying heavily on silage, for example to produce 4000 litres of milk from forage, spending on an effective additive is worthwhile.

But always consider the cost of the additive, advises Dr Wilkinson. Mr Lannigan treated 1500t of silage at about £1/t. That £1500 would buy 16t of treated wheat for feeding at £95/t, equivalent to feeding 1kg a cow a day through the winter.

Mr Lannigan also believes in following silage making rules for cleanliness in the pit, short chop length, quick clamp fill, and using two side and three top sheets, which cost an extra £100 but, he suggests, saves £500 in time and feed. He has also reseeded silage pasture that had a high proportion of poor grasses and weeds when he took over the farm in 1994.

"Before 1994, silage quality was poor because of poor grass varieties, so as part of the policy to improve silage quality we started using an additive. Since then, the silage has been stable. Even when taking a week to work across the face, with a block cutter, it has stayed cool," says Mr Lannigan.

There are potential advantages from improved animal performance and reduced protein breakdown on offer from an effective inoculant, adds Dr Wilkinson.

Mr Lannigan has used Genus Live System because the research showed that it dropped pH quickly and he had seen the independent research evidence to support its claims. He was yet to see any evidence to disprove this claim or prove another additive was better.

Dr Wilkinson agrees that independent additive research results, in conditions similar to those of your own farm, should be inspected. Also, check the recommended rate of application is the same as in trials and that the bug type and number have not changed.

Mr Lannigan adds that he would consider using an acid when rain was forecast and grass cut, but his contractor was not keen on acids, which rotted foragers. There were also safety concerns with handling acids.

But what made an additive good value for money? asks Dr Wilkinson. Should Mr Lannigan stop using an additive?

He is reaping the benefits of better silage quality, which made it difficult to stop using one, he says. &#42

Smell and feel silage to check the additive has worked, says Mike Wilkinson.Good silage should not smell fruity or butyric or feel slimy.

ADDITIVE CHOICE

&#8226 Did last years additive work?

&#8226 Are research results positive in circumstances similar to yours?

&#8226 Why are you using an additive?

When silage must be made of wet grass or poor grass varieties, choose an acid, Leeds Universitys Mike Wilkinson (right) advises Paul Lannigan.