Cutting as early as possible in the season, weather permitting, will produce the highest quality hay.
It is inevitable that some quality will be lost during the curing and harvesting process.
So what can be done about reducing the losses and improving hay quality?
Once the decision to cut has been made, increasing the rate of drying of the entire crop, particularly the stems, is the key to reducing losses and avoiding the risk of rain damage.
Growing plants contain about 75 to 80 per cent water at the time of harvest.
When the plant is cut, it continues to respire or breathe until water content is reduced to about 40 per cent, i.e. 60 per cent dry matter.
Some loss of dry matter and quality has occurred.
Below 40 per cent moisture, the leaves dry at a much faster rate than stems because they are very thin and have a large surface area to mass ratio.
However, stem drying occurs slowly due to the cell make-up and surface wax layer.
By the time the stem reaches appropriate moisture content for baling, the leaves may be too dry and therefore easily shattered.
Wait for any dew to lift before mowing — there could be one to three tonnes of moisture trapped between the plants if they are mowed with dew on them, moisture which must be dried off before the plants start to cure.
Mowing in the rain would have a similar effect.
Use a mower-conditioner or conditioner
The most common method of enhancing stem drying is by mechanical conditioning which uses a set of inter-meshing counter-rotating rollers.
These are designed to crush, bend or break stems, allowing moisture to escape more easily.
Conditioners also reduce leaf shatter during raking and baling, as the leaves tend to dry at around the same rate as the stems.
Proper roller clearance adjustment is important, especially for roller-type conditioners. Don't have them set too wide. The roller spacings used for thick-stemmed crops are often not adequate for finer-stemmed crops.
The flail or tined-type mower conditioners are more suited to pastures than the roller type. They do a better job of the crimping and abrading, and tend to leave the windrows ‘fluffier’, which is more conducive to quicker drying.
In both cases, leaving the swathe boards out as wide as possible, to leave wider windrows, will greatly increase the drying rate.
Tedding straight after mowing
A technique recommended for silage, tedding (spreading) will also reduce the curing time of hay by about 30 to 40 per cent, if used within a few hours after mowing. Some farmers use the tedder the day after mowing, but the curing rate would benefit greatly if done soon after mowing.
Some farmers worry about hay bleaching when using these machines, however tedding will allow far more even and quicker drying, so bleaching should be minimal.
In any case, bleaching does not greatly affect hay quality, although it does reduce the carotene levels.
The reduced risk of rain and its effect on reducing quality is reason enough to consider using a tedder, especially if rain is expected.
Raking
Raking is used to enhance uniform drying. The most common type of rake rolls and fluffs the windrow, bringing the bottom layer to the top.
The rolling action exposes more of the stems while protecting the leafy portion of the plant. Hay should be raked at moisture content above 30 per cent, to minimise leaf shatter.
Leaf loss can be further reduced by raking during early morning or late evening after the leaves absorb moisture from the air.
As much as 15 per cent dry matter can be lost if legumes such as lucerne are raked at the wrong time, however pasture losses tend to be less.
When to bale
Optimum moisture content for baling hay for conserved feed depends on bale size and density. For small rectangular bales, the moisture content should be no higher than 18 per cent.
The upper limit for large round bales should be 14 to 16 per cent and large square bales 12 to 14 per cent.
More than 80 per cent of hay fires have been in large square bales which have often been baled at the correct moisture content, but their high density does not allow for breathing, hence there is no room for error with these large, very densely packed bales.
● For more information on growing quality hay, visit: agriculture.vic.gov.au
