Special steps should be taken reduce the risk of mycotoxins in this year’s maize crops, say silage and nutrition experts.
Toxic substances produced by certain types of fungi, mycotoxins are becoming more prevalent in maize silage across the UK due to more crops being grown in marginal areas and unpredictable weather patterns.
Failure to manage mycotoxins in maize silage could cost farmers lost milk production this autumn and winter, says Lientjie Colahan, forage technical support for Lallemand animal nutrition.
“Mycotoxins are an invisible threat – they have no smell, colour, or taste. They’re produced by moulds in response to stress, such as drought, excessive rain, or extreme temperatures. Unfortunately, tests available to detect them are quite limited.”
Although mycotoxins come from moulds, the presence of mould doesn’t always mean mycotoxins are present. Farmers should monitor crops closely, aim for clean silage and use a crop- and condition-specific inoculant, says Ms Colahan.
Growers should regularly walk maize crops and check for mould growth on leaves and cobs is essential. Any moulds on the plants are likely to become stressed and produce mycotoxins when you harvest them and bring them into the clamp.
“Watch cobs closely in particular,” explains Mrs Colahan. “Any smut will not only reduce the crop quality but also be a sign that other moulds – which could produce mycotoxins – are present as well.”
The best way to reduce mycotoxin risk at harvest is to produce as clean a crop as possible. Although mycotoxins can occur in all silages, they’re most commonly found in maize.
“This is partly down to the risk of rain at harvest, which not only creates a stress point for moulds on the plant, but also increases the risk of soil contamination in the clamp,” explains Mrs Colahan.
Silage clamps
Soil contains millions of mould spores – increasing the risk of mycotoxin development. Forage cutting heights should be adjusted to reduce the risk of soil contamination in the clamp, which should be rapidly filled, with proper compaction.
“When sealing the clamp, non-porous oxygen-barrier plastic films can be used to reduce oxygen penetration in the silage, and the clamp should be regularly monitored to ensure everything remains secure and sealed,” adds Mrs Colahan.
Farmers are also encouraged to be prepared to harvest earlier – rather than later – to avoid harvesting in difficult conditions, which increase the risk of soil contamination.
“It’s better to lose a little in starch and get the crop off in one day under good conditions, than holding out for extra starch and ending up with a prolonged harvest in the rain and mud.”
“In the past, many farmers have been caught out when it started raining and there was never a dry spell that lasted long enough for the field to dry out so you could travel on it and get the crop in.” Farmers should familiarise themselves with the signs a crop is ready to cut. If the bottom two or three leaves are drying off and turning brown, then the crop is close to being ready for harvest, provided it’s not a stay-green variety. “The milk line on the kernel also provides an indication of harvest readiness and as the sugars in the plant convert to starch, this line moves; generally, if it’s a third of the way down the kernel, the crop is ready to harvest.”
Inoculant
Finally, Mrs Colahan recommends the use of a crop- and condition-specific inoculant to manage the risk of mycotoxins in maize silage. In turn, this will help ensure the best quality maize silage is available to cattle.
Inoculants containing antifungal bacteria, such as Lentilactobacillus hilgardii CNCM I-4785 and Lentilactobacillus buchneri NCIMB 40788, reduce the occurrence of moulds and, in turn, mycotoxins.
“This was proven in a trial at Lallemand’s Forage Centre of Excellence which found treating maize silage with an inoculant containing these two bacteria reduced yeasts and moulds by 99.9%,” adds Mrs Colahan.