Livestock feed which has been damaged during recent flooding can still be used, but needs to be carefully managed.
It should only be fed with caution and only to certain classes of livestock, according to Dave Davies, director of Silage Solutions.
Speaking during an AHDB webinar, he said farmers needed to minimise the risk of feeding spoilt forage to livestock.
As a first step, he suggested they assessed whether they actually needed the damaged forage or could avoid using it.
If it was fed, it should only be given to growing animals and not to those either producing or pregnant, which face higher disease pressures.
Unharvested forage maize could also be usable, but would need careful harvesting and preparation if its full feed value was to be realised.
The extent to which flooded forage might be contaminated could depend on the source of the flooding.
If it was river water the risks were likely to be much lower than for slurry and other wastes.
Mr Davies said if flood damaged silage was fed, farmers needed to know its dry matter (DM) content and adjust rations appropriately.
He explained while the average DM content of a flooded bale might be 32 per cent DM, that could hide variations from 36.9 per cent DM at the top of the bale to 30.2 per cent DM at the bottom, and in flooded clamps the variations could be even greater.
That made taking representative samples from right across the crop important.
Mr Davies said failing to check DM could alter the concentrate to forage ratio of any diet, which risked compromising the production and health of the animal.
Flooded silage should also be tested for nutritive value, because water soluble nutrients were likely to have been lost.
Damaged bales must be fed carefully, particularly if mould was apparent. He suggested comparing it with an unaffected crop to check for any changes.
If both samples smelled similar then there might not be a problem, but if a touch test revealed sand grit or silt then soil contamination should be suspected.
Mr Davies said: “If it feels slimy as well then there has been more clostridia ingress.”
He also said mouldy areas and a buffer zone around them should be excluded from any feed.
“The clostridia will have moved from the mouldy area into the adjacent part of the bale, so that needs to be removed.”
Where bales had suffered irreparable damage, Mr Davies said they should be fed immediately rather than retained.
Damaged bales could be repaired and retained, but should be marked clearly so farm staff did not forget about the damage and feed them inappropriately.
He said: “Never feed flood damaged silage to dry or transition cows or pregnant ewes. Those are your most important livestock and the most vulnerable to disease.”
Is it too late to harvest maize?
MR Davies said forage maize could still be foraged or combined in January or February if ground conditions prevented it being taken earlier, but foraging the whole plant might be risky.
He said: “The stem and lower leaves may be heavily soil contaminated. They will also be dead and have little nutritive value.
“If there is visible mould on the plant, it could increase aerobic spoilage and mycotoxin levels.”
Raising the cutting height to 30cm instead of 10cm would reduce contamination risks and remove low-nutrient material from the final silage.
If crops were combined, Mr Davies urged farmers to ensure the seed crackers were working efficiently because the seeds would be harder than normal and must be cracked for their full nutritive value to be realised.
He added that starch content might also be higher than normal and, ironically, given the wet weather, the silage might have a higher DM because the plant was dead.