Principles of making big bale silage
The principles of making big bale silage are similar to those for conventional silage:
The crop should be grown as for clamp silage.
Harvest leafy, digestible grass. Silage made from this material has a higher feeding value than silage made from stemmy (low digestibility) grass (Table 1)
Table 1. Effect of digestability on animal performance.
Beef Production |
Milk Production | ||||
|---|---|---|---|---|---|
| D-Value | 73 |
59 |
72.5 |
62 |
|
| Liveweight gain (KG/day) | 1.10 |
0.78 | Milk yield(KG/day) | 28.9 |
26.3 |
| Carcase gain(KG/day) | 0.63 |
0.43 | Protein % | 3.35 |
3.17 |
| % improvement from increasing D-value | +56 |
+16 |
Source ARINI Hillsborough
- Wilt grass to 25 - 30 % DM within a day of cutting
- Ensile clean grass without contamination by soil, manure or rotted grass (salvaged hay crops).
- Produce well shaped, dense bales.
- Seal the bales quickly in an air tight environment and maintain these conditions prior to feeding.
- Protect the bales from damage during handling and storage.
- Adopt simple feeding methods.
Wilting for baled silage
The wilting of grass prior to baling has several advantages:
- It eliminates effluent production when a DM concentration in excess of 25 percent is achieved. At lower DM contents effluent will seep from unwilted bales
- The number of bales per hectare are reduced (Table 2) which lowers costs.
Table 2. Possible bale production per hectare (25 t/ha crop @ 18% DM)
Grass DM % at baling |
|||
|---|---|---|---|
| Bale weight (kg) | 18 |
25 |
35 |
| Number of bales per hectare | |||
400 |
- |
- |
32 |
500 |
- |
36 |
25 |
600 |
41 |
30 |
21 |
700 |
35 |
35 |
18 |
800 |
31 |
22 |
- |
900 |
27 |
- |
- |
Source Teagasc, Grange
- Bale are lighter and easier to handle.
Grass should be wilted to 25-30% DM ideally within 24 hours of cutting to minimise field and feed losses. The rate of wilting however will depend on grass yield and type, weather conditions and swath treatments. Spreading/tedding the grass with rotary type tedders to give 100 percent ground cover produces the fastest drying rates. Combining swaths from successive mower runs gives the slowest drying rates. Mower conditioners can produce swaths that should give reasonable drying rates relative to conventional mowers (Table 3)
Table 3. The effect of swath treatment on the drying grass
| Single | Single | Auto swathed | Spread | |
|---|---|---|---|---|
| Conditioner | No |
Yes |
Yes |
Yes |
| DM % - 0 hours | 16.0 |
16.0 |
16.0 |
16.0 |
| DM % - 24 hours | 21.5 |
22.7 |
19.3 |
29.2 |
Source ARINI Hillsborough
Produce a dense, well shaped bale when baling grass
Baling guidelines
The objective is to produce a dense, well shaped bale. The following points require attention in order to achieve this objective:
- Wilt the grass if possible
- Prepare a wide, even, box shaped swath for baling. The width of the swath should be 1.1-1.2 m, although wide baler pick-ups can handle 1.4 m swaths.
- Adjust the baler density setting to its maximum allowable position
- Avoid excessive forward speeds.
- Using a chopper baler can increase bale weights by up to 20 percent.
Wrapping
Originally all big bale silage was bagged, which was generally satisfactory. The main problem was the prevention of damage to bags which led to spoilage. It is now more common for bales to be wrapped using 500 or 750 mm wide rolls of plastic film. The plastic is stretched using a stretching unit fitted to the bale wrapper, before being reduced slightly and applied around the bale. Stretch film should meet certain requirements before use:
- It should have good mechanical properties
- A high level of tack (stickiness)
- It should be stabilised for protection from damage by sunlight (UV).
White films reflect more heat than black films reducing heat damage. It is essential to the success of the bale wrapping procedure to create and maintain an airtight seal around the silage. The following points require attention:
- Wrap bales as soon as possible after baling
Wrap bales at the storage area. Standard flat bed trailers can be used to transport a number of unwrapped bales at any one time.
Wrapping
Wrapping
- The normal setting for the pre-stretching unit is 70 percent. Settings in excess of this value weaken the plastic film.
- Align the pre-stretching unit to the bale.
- Clean the rollers regularly to avoid a build up of tack.
- Avoid wrapping bales in wet conditions.
- Apply four layers of plastic film to the bale. This corresponds to 14-16 revolutions of the wrapper turntable. Applying six layers of film to a bale will increase baling costs. However studies have shown reductions in effluent production from bales wrapped with six layers of film compared to bales wrapped with four layers of film (Table 4). Reductions in effluent production can also be achieved by using 750 mm film instead of 500 mm film.
- If bales are to be wrapped in the field, transport the bales to the storage area within one day of wrapping and avoid damaging the plastic wrap.
- A good bale drop table causes less damage on tipping than a bale mat.
Transporting bales
Table 4. Effecty of wrapping on effluent production from big bales (750mm film)
No of wrapping layers |
||
|---|---|---|
4 |
6 | |
| Silage DM % | 22 |
22 |
| Effluent produced (litres/t) | 28 |
11 |
Source IGER, Aberystwyth
