Maize-silage analyses reveal variable quality

13 Nov 2019

While initial results for maize silage are encouraging, producers are being warned that later harvested crops will need careful monitoring.

Reporting on the results from more than 870 samples received so far at its laboratory in Ashbourne, Trouw Nutrition GB’s Liz Homer says that the feed value of early harvested crops is comparable with the 2018 season.

Incomplete fermentation

“Crops are typically well-fermented, but more than 10% of samples received had to be discarded due to incomplete fermentation – probably reflecting a need to get maize into diets quickly,” she explains.

At 32.6% dry matter, 11.6 MJME/kgDM and 31.2% starch, early crops have analysed close to those cut in 2018. Starch degradability is also similar and bypass starch levels are good.

Acid load

“Early maize silage appears to be fermentable with high levels of total and rapidly fermentable carbohydrate. But this results in an increased acid load that, coupled with a low fibre index as a result of lower NDF, may affect rumen health unless diets are carefully balanced.”

Overall, Dr Homer believes that early maize should complement this year’s grass silages well. The high level of fermentable carbohydrates and glucogenic energy will balance the high NDF and lignin values in grass silage. But she warns that the total diet will need careful balancing.

Bypass protein

“It will be about feeding the right supplements rather than what is simply cheap,” she says. “Cereals, for example, may need to be trimmed back despite being good value because there will already be a good supply of fermentable carbohydrates from the maize. Many diets will also require a supply of bypass protein.”

While the news is encouraging for producers who were able to get maize harvested before the weather broke, Dr Homer says the protracted harvest could have implications for feed quality in later harvested crops.

Starch content

“These crops should have a higher starch content, but they will also have higher levels of both NDF and lignin. This will affect how the crops will feed, so regular analysis throughout the winter will be essential.”