Managing silage to minimize mycotoxins

This year’s difficult season means livestock farmers will have to pay particular attention to managing their entire silage process if they are to avoid a high mycotoxin challenge, suggests Dr.Dave Davies of Silage Solutions Ltd.

’It’s not only that we’re getting our much needed rain just as many livestock famers are getting close to harvesting their first cut,’ says Dr Davies. ’The conditions we have already experienced have been very challenging for plants: a very dry and warm February and March followed by a cold and wet April and early May. This means silage crops are already stressed and more vulnerable to attack by fungal pathogens, leading to a greater risk of aerobic spoilage at feed-out, and field formed mycotoxins.’

Mycotoxins are poisonous compounds produced naturally by moulds. Many people believe that these highly toxic compounds are only associated with visible moulds, however mycotoxins can still be present where no mould is visible. Similarly, just because mould can be seen doesn’t necessarily mean mycotoxins are present.

’However, you can be sure that moulds and mycotoxins are bad news for silage,’ comments Graeme Smith, Alltech UK’s Ruminant Sales Manager, ’and the main moulds of concern are aspergillus, fusarium and penicillium. These produce a wide range of mycotoxins that at best can reduce animal performance and at worst cause livestock disease.’

So why is this season particularly challenging? ’The early season has already left plants stressed and vulnerable. Now, the rain has given good grass growth, but lodging of the crops has become a significant problem that again favours mycotoxins,’ continues Mr Smith.

Lodging leads to the base of the sward dying and increased contamination with moulds that live on dead and decaying plant material such as penicillium. Lodged crops are more difficult to cut cleanly without contamination so resulting in a higher level of dead material entering the silo. This in turn increases the risk of poor aerobic stability at feed out and the mycotoxin load in the silage.

So, what can be done to counter this increased challenge? ’Careful attention to every detail of the silage routine will help mitigate the mycotoxin challenge," says Dr. Davies, ’and good consolidation is the best way to reduce the growth of harmful yeasts and moulds in the silage clamp and to improve the aerobic stability at feed-out.’

Silage: avoiding mycotoxins

’ Mow grass when it is dry

’ Aim for a stubble height of 7 to 10 cm

’ Spread crop immediately after mowing

’ Spread sward to encourage wilting

’ Don’t leave a thick, dense sward ’ the perfect environment for mould

’ Ensure the crop is consolidated well in the clamp

’ Use sufficient weight - consider a silo-compacter - to help this process

Finally, when feeding silage watch for signs of mycotoxin problems in the herd: these include reduced intake and milk yields, reduced fertility and loose dung. Including a broad spectrum mycotoxin binder in feed should help to solve the problem.

’Avoid a binder that contains any traces of clay,’ concludes Mr Smith, ’as these can lock up valuable trace elements and vitamins. An animal experiencing a mycotoxin challenge is already under huge biological stress without being denied valuable nutrients. Products containing clay are also ineffectual against penicillium borne mycotoxins and your money would be better spent elsewhere.’