Maize Update

Published 25 January 13

Research has widely found that the rumen degradability of starch in maize silage increases during storage, says Adam Clay, Ruminant Manager at Frank Wright.  

"The maize starch granule is hard at ensiling. However, during storage in the clamp the granule begins to slowly soften, changing the rate at which the starch degrades and becomes an available energy source forthe rumen microbes," he explains. "The research data shows that this change is particularly evident after four months of storage."

In practice most maize silage sampling and analysis occurs at the beginning of the winter once the crop has settled in the clamp. Reanalysing the maize silage crop four months or more after ensiling may give a different picture of rumen energy supply and necessitate reformulation and rebalancing of the ration.

"Cows showing increasing signs of acidosis as winter progresses, without apparent changes in the diet, may be as a result of the increasing rumen starch availability from maize silage," Adam says.

Adam continues; "The measured dry matter degradability of maize silage as compared to the single standard value from Feed into Milk (FiM) can be significantly different. Therefore the rumen energy supply can be significantly overestimated when using the standard FiM degradability values.

"Whilst starch degradability will have increased through winter storage, this year's crop began with 11.82% less rumen degradable than the 2011 crop. Taking another analyses will be especially important in order to understand rumen energy supply and to ensure consistent rumen health," he concludes.