Thursday, 28 October 2021 11:55

Maize silage quality myths - are they fact or fiction?

Written by  Ian Williams
Many smaller cobs produce more energy per hectare than fewer large cobs. Many smaller cobs produce more energy per hectare than fewer large cobs.

Maize silage is an essential part of many dairy farm systems. Research shows that yield is king, and for on-farm growers, the most profitable hybrid is almost always the highest yielding one.

However, for some farmers, there is an increasing focus on increasing the quality of their maize silage.

There are varied ideas as to how to achieve higher quality maize silage. It is important that we separate fact from fiction. This article looks to do just that.

Lower populations mean higher quality maize silage - fact or fiction?

Fiction. The thought behind this is that a lower population results in bigger cobs. Plants with bigger cobs must produce higher quality maize silage than plants with smaller cobs. The first part of the statement is true. If you want big cobs, plant less seed. But if you plant less seed, you will also get bigger plants which have more fibre. Graph 1 summarises a New Zealand maize silage population trial. It clearly shows that as population went up, feed quality didn't change. Increasing plant population increased maize silage yield. More yield means lower cost feed.

Cob to stover ratio is all you need to worry about - fact or fiction?

Fiction. The most important drivers of maize silage quality are starch and sugar content and fibre digestibility. The more starch and sugar, the higher the energy value and the higher the fibre digestibility, the more the cow can consume. The cob is a mix of husk leaves, grain and cob core. The cob to stover ratio doesn't take into account how much starch is in the cob or how digestible the maize plant is.

Hybrid choice affects silage quality - fact or fiction?

Fact. The work by the Pioneer research team in NZ shows distinct genetic differences in quality between hybrids. Simply put, some hybrids produce more grain (and therefore more starch) and have higher fibre digestibility than others. Farmers wanting high quality silage can choose hybrids that have high ratings for starch and sugar and whole plant digestibility. Pioneer uses quality data collected from New Zealand maize silage trial plots to generate the ratings in their maize seed catalogue. Not every company has such a rigorous trialling programme in place.

There is no difference in starch availability between dent (soft starch) and flinty (hard starch) endosperm hybrids at silage making time - fact or fiction?

Fact. From time to time a company tries to sell their hybrid on the basis that starch from their hybrid is more digestible. A large number of independent trials have shown there is no difference in the digestibility or milk production potential of hybrids with differing endosperm types (hard or soft starch) at silage harvest time.

Cob size matters - fact or fiction?

Fiction. Cob size has very little impact on maize silage quality. Desperate salespeople (who usually lack yield and quality data) will often produce cobs from the hybrid they are trying to sell to show that their cob is bigger (and therefore better) than the hybrid they are comparing it against. More important than cob size is the total energy harvested per hectare because that is the milk production potential. Many smaller cobs produce more energy per hectare than fewer large cobs.

Milky silage makes more milk - fact or fiction?

Fiction. Harvesting maize too early (e.g., below 32%) when the cob is milky results in significantly lower silage yields and slightly lower feed quality. Really wet silage can be difficult to ensile well and there is an increased chance of run-off from the stack. As a plant matures toward black layer, the plant continues to lay down starch and this results in an increase in feed value. The ideal harvest window for maize silage is somewhere between 32 and 38% dry matter.

Farmers can manage their maize to increase the quality of their maize silage - fact or fiction?

Fact. While hybrid and environment have a huge influence on maize silage quality, management of the crop can also play a part in influencing silage quality. Farmers can influence silage quality by ensuring the crop does not run out of water or nutrients, controlling weeds, harvesting at the optimal time and ensuring the crop is well ensiled.

Ian Williams is a Pioneer forage specialist, This email address is being protected from spambots. You need JavaScript enabled to view it..

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