A general rule is to allow 0.8 to 1.0 tonne of feed for each beast in the feedlot, depending on the type of stock and the time it will take them to reach market condition. When feed is in short supply, be certain you have enough feed on hand to ‘finish’ the cattle.
For feed storage generally, you will need a hayshed, grain silo and grain auger. If you do not have a silo, you can fabricate a grain bin from 75 × 75 × 4mm steel mesh. Line it with hessian or polypropylene for a convenient temporary grain storage.
These bins can be erected in an existing shed or in the paddock. One roll of welded mesh, 14.5m long and 2.3m high, will hold about 30 tonnes of grain.
In a drought situation, it may be necessary to harvest early, when grain has a higher moisture content. This high-moisture grain can be stored in low-cost temporary bins, such as those described above, in a shed.
In such circumstances, high-moisture grain can be stored for short periods (12 months) by adding propionic acid. This may overcome the need for processing and could become standard practice in normal seasons.
|Grain moisture content (%)||Add propionic acid (litres/tonne grain)|
Particularly check whether the feed concerned has been stored and treated to protect against insect or other predators. Observe all relevant withholding periods for the treated feed before feeding it to stock.
Best results are obtained when grains are coarsely milled, as they can cause digestive upsets if crushed too finely. Powdery feed is less palatable and can also cause respiratory problems. Soaking grain in water for up to 3 hours before processing will reduce shattering of the grain. Soaked grain helps reduce bloat problems and improves weight gain when processed.
To reduce problems with finely processed feed:
Roughage is best cut to under 10 cm lengths. Roughage that is too finely chopped can lead to digestive upsets. Although good quality roughage can be chopped to 3–5 cm lengths, poor quality (especially very dry) roughage needs more length to minimise powdering.
The type of milling and mixing equipment you use will depend largely on the number of stock to be fed.
Roller mills are ideal for grain preparation because they eliminate dust and crack the grain into small pieces rather than smash it. A 250 mm mill can process 5 tonnes an hour and a 500 mm roller mill can handle up to 15 tonnes an hour.
Roller mills generally require less power than hammer mills.
Hammer mills have the advantage of being able to process both grain and roughage, but they can pulverise grain and hay unless care is taken to use the correct screen size. This is particularly important with lucerne and pasture hay.
Screen size is critical. Remember that you don’t want to pulverise grain or roughage. You may need to experiment with different screen sizes to find what gives you the best result.
Suggested screen sizes are:
The speed at which a mill is driven and the rate at which hay or grain is fed into it can vary the degree of crushing. You may have to experiment on a trial-and-error basis to get the best grain crack.
A 380 mm hammer can process 4 to 6 tonnes an hour, depending on screen size. With roughage, the moisture content has a significant impact on the speed. Very dry roughages can be milled faster.
Hay cutters are expensive but give a better and more controlled roughage sample than hammer mills, as well as having a higher output (up to 250 bales per hour). A forage harvester can be used satisfactorily as a stationary hay cutter.
There are two basic types of feed mixer: vertical mixalls and horizontal feed-mixing carts. Both mill and mixer capacities will vary according to type of hay and grain used and the texture of meal being made. In general, the capacity of mixers is limited with high-roughage mixes. Examples of the mixing capacity of a typical vertical mixer are given in table 7.
|Type of operation||Vertical mixer capacity (kg)|
|Oats milled on 6 mm screen||900|
|Grain sorghum milled on 6 mm screen||1800|
|60:40 hay/grain mix||700|
|25:75 hay/grain mix||1300|
One person using a vertical mixall-type feeder would take up to 3 hours to feed 150 head of cattle. Horizontal feed mixers, having a bigger capacity, are better if more than 400 head are being fed.
Chopped hay, green feed or silage can be put into the self-unloading box and topped off with a layer of grain and premix. Once the unloading mechanism is put into gear, the grain and roughage will be mixed as they tumble into the feed trough. These boxes come in 5.6m3 and 11m3 capacities. They are particularly useful for high-roughage rations.