By Frank Mickan, Dairy Extension Officer, Ellinbank
PLASTIC wrap is not a silver bullet for hay that was rain affected before baling or for hay that is too wet or for silage that is too dry at baling.
Some hay seasons have resulted in the above scenario and a response by many these days seems to be: “Wrap it in stretch wrap plastic and turn it into silage”.
However, there is no cut and dried right answer here.
Sometimes you may get away with avoiding mouldy hay by wrapping it but more often than not, you won’t.
Since it’s probably mid to late November/early December when making hay, most pastures will have a lot of stem with seed heads prominent.
This means the quality of the forage on the ground will be well down, probably under 9.5 megajoules of metabolisable energy per kilogram of dry matter (MJ ME/kg DM or ME), approximately 9 to 11 per cent crude protein (% CP) and over 50 per cent neutral detergent fibre (% NDF).
Conversely, the leafier the crop and higher the clover content, the higher the quality (over 10 ME, over 14 % CP and under 45 % NDF).
The dry matter (DM) content may be about 70–80 per cent, i.e. moisture content 20–30 per cent so the forage will be too wet for hay but generally too dry for silage.
I call this the ‘danger zone’ and the result is often mouldy and/or foul smelling fodder.
This is because there is not enough moisture to allow a satisfactory lactic acid type fermentation which converts plant sugars to acids which preserves the crop as silage.
Conversely, there is enough moisture to allow some plant respiration and microbial activity resulting in heating and mould growth.
If bales of late maturity forage have been wrapped in stretch wrap plastic to “become silage” their high proportion of stems to leaves allows a lot of air to be trapped between and even within the hollow stems.
Same result as above, very often mouldy and less-than-pleasant to bloody horrible smelling silage with reduced palatability.
Another issue caused by rain is that soil is often splashed onto the forage or inadvertently picked up by further tedding or raking.
This soil contains undesirable soil organisms which can contribute substantially toward a poor fermentation and plastic won’t prevent this.
Sometimes, you will get a win! To increase your chances you will need to individually or continuously in-line wrap the rounds or squares.
Don’t even think about saving money by stacking ‘Danger Zone’ large squares under sheets of plastic as I have heard of too many farmers who were disappointed with the outcome.
If the moisture content is only three to six per cent above the ideal baling moisture content, the best outcome might be to stick to baling it as hay, but apply a reliable hay preservative.
Always use hay preservatives at the correct rate, remembering wet hay is much heavier than cured hay, and ensure the preservative covers as much of the forage as possible.
If the crop is pasture or lucerne and is medium to high quality, this means more leaf and less stem, or thinner stems for the lucerne, the same story still applies as in the first scenario.
However, there will be less air trapped in these more tightly packed bales and this time you are starting with a higher quality base with plants containing more sugars for the bacteria to work on.
The closer this forage is to silage dry matter and although there will still be a drop off in quality, the chances of a positive outcome are somewhat higher, but no promises.
There is no magic answer to ‘is it worth wrapping material too dry for silage or too wet for hay?’ and unfortunately Mother Nature has not been on the hay/silage maker’s side over some recent years.
But, if the raw product was bad to start with, then the end product will be too.