A recent analysis of maize silage has suggested that it may not provide the expected production boost this winter due to the substantially different growing seasons witnessed this year and last year.
Trouw Nutrition GB ruminant specialist Tom Goatman has discussed the contrasting harvests seen in 2015 and 2016. He says: “last year, farmers delayed harvest in the hope that crops would eventually mature, with many maturing at least two weeks later than expected. They were then hit with very wet weather which made harvest a lottery.
This year, favourable growing conditions and a typically warm September meant crops matured quicker, and a dry October made for near perfect conditions”.
Mr Goatman highlights that this year’s sample is much drier at 34.4 percent. The metabolisable energy (ME) content is lower at 11.4 megajouls (MJ) compared to 11.6 MJ last year. Only 31 per cent of samples have an ME over 11.5 MJ compared to 57 per cent last year.
He continues: “the difference in ME is partly due to a lower starch content. Significantly, starch degradability is also lower and as a result, bypass starch levels are higher”.
The other factor influencing lower ME is the reduced digestibility of the vegetative parts of the plant, meaning less energy is available from the stem and leaves.
Lower starch degradability and higher bypass starch means less carbohydrate energy will be available for rumen fermentation.
It is advised to take care when balancing early winter diets to ensure livestock get the most from early season maize.
It is likely that in the early winter, the usual boost that maize gives to production will not be evident, because the change in starch content will impact rumen fermentation. Mr Goatman suggests increasing the supply of rapidly fermented carbohydrates available from other sources such as wheat to ensure the diet provides sufficient quickly available energy to support effective microbial and rumen function.
He says: “Later on, as starch degradability in maize increases, these supplementary sources can be trimmed back, helping to reduce diet costs.”
“The reduced starch degradability will also help improve rumen health. Lower starch degradability mean fewer carbohydrates will be available for rumen fermentation. This coupled with the increased dry matter content and lower lactic acid content mean that this year’s maize has significantly lower acid load”.