SPRING grazing management and silage are currently top of mind for dairy farmers and Dairy Australia has released two new resources to help in the decision-making process.
There are varieties that can be harvested at the normal chop heights and still have the quality that is required to make high production of milk.
There is also a process called Shredlage that rips the fibre apart to allow greater access by the rumen bacteria to the energy in the Neutral Digestabile Fibre (NDF).
There are several of these units in harvesters in Australia now, and I expect more used.
This report would have benefited from the actual readings of the energy, starch, NDF and Acid Detergent Fibre (ADF) of the two cutting heights and the background to the actual trial set up, to show the difference from the cows - which I suspect is only based on numerical feed test results and a nutritional program to estimate milk production.
I oppose the harvest time suggested, with half milk line, as the best way to increase the amount of starch in corn silage is to get the grain to black layer and use a hybrid with good staygreen to allow it to be pitted well.
Adjusting the processor on a chopper to ensure the kernals are smashed and the fibre can be ensiled well, leads to the dry matter content being closer to 38-42% where you will have full starch lay down in the kernel, as after all, it is the grain that is the most important part.
If we take it at half milk line, serious amounts of starch and dry matter is being forgone, as for every day of growth up to black layer, there is anywhere up to 150 kg DM/day of yield being added, mostly in the form of starch.
The number I used in good corn silage was 40+% starch, low 30s NDF.
I was able to achieve these numbers at normal cutting heights with different hybrids across many regions in Australia and New Zealand.
You can also manipulate the starch digestablity by selecting hybrids with dent xdent breeding or the best dent x flint (weighted heavily to the dent parentage).
And you also get more from the starch by leaving it for longer in the silage pit, as from as early as three months the starch to protein bonds start to break down, which is very important for the varieties that are often used in Qld that tend to have more flint parentage.
The best period is after six months in the pit.
Ensuring the plant had adequate nutrition, with particular regards to Potassium, is directly involved in fruiting, and moisture regulation.
As you can see, there are many ways to manipulate the quality of corn silage without leaving dry matter yield behind in the paddock.
I am not saying that you won’t gain a little lift by increasing the chopping heights, but there are many other ways to improve corn silage without having to do that and leaving yield in the paddocks (even though it’s not wasted, as it can go back to organic matter for the soil, or dry stock can graze it, it just adds to the cost of the silage).
Dean Fry, Torrumbarry, Vic