Introduction
It is critically important that the silage operation be integrated into whole farm management and not viewed in isolation. Silage is a means to an end, not an end in itself.
There are many potential roles for silage in grazing systems. These are summarised in Table 1.4. Their relative importance will vary from enterprise to enterprise, and from region to region.
Conservation of surplus pasture and specialty crops as silage can play an integral role in matching feed supply with requirements, improving pasture utilisation and management, and profitability on dairy farms.
Production benefits
- An increase in the yield, quality and utilisation of pasture grown. This will improve milk production per cow, increase stocking rate and increase ‘whole farm’ productivity.
- Transferring forage from times of surplus to times of deficit reduces the need to buy other supplementary feeds to sustain milk production.
For example, on a typical Queensland dairy farm conserved forage is used to overcome feed deficits in the March to August period (see Figure 1.5). As production systems intensify, the current trend is for the silage component of the diet to increase at the expense of grazed pasture. In southern Australia, silage is used to fill quantity or quality feed gaps in late summer, autumn and winter.
- A portion of the farm can be set aside to grow high-yielding, high-quality specialist crops for silage, increasing the total amount of forage produced on farm. This can lead to a further increase in stocking rate.
- Purchasing pasture or crop for ensiling on farm is becoming a useful strategy for dairy farmers who are already fully utilising their forage resources, enabling them to expand their business without having to outlay capital to buy additional land.
- Silage can be the key feed resource that allows dairy farmers to expand and intensify their production system. Better economies of scale can be achieved by using silage to increase milk production on the farm, reducing overhead and labour costs per litre of milk produced.
Dairy cows feeding on silage
Additional Benefits
Silage can be used as a supplement for replacement heifers when pasture supply and quality is insufficient to ensure adequate growth rates before joining.
In many situations, it is more efficient to use available water to produce crops than pasture.
Producing silage during favourable times of the year can reduce reliance on irrigation to produce pasture for grazing.
This water is then available to higher-value crops such as maize.
Irrigation water may be more effectively used by irrigating during spring or autumn when evaporative losses are lower, rather than during a hot, dry summer.
In many areas, surplus forage can be produced more cheaply during these periods, and conserved as silage for later use.
Silage can be used to balance the dietary intakes of dairy cows by supplying fibre to cows grazing lush pastures or receiving concentrates.
Legume silages can be used to supply additional protein to cows consuming low-protein feeds, such as maize or sorghum silage.
- Where there are price incentives to produce ‘out-of season-milk’, silage can provide the feed needed for the required change in calving time.
- Silage can be a valuable drought, flood or bushfire reserve.
- Silage can be used as a replacement or `buffer feed’ to allow grazing management objectives to be achieved without a significant penalty in milk production.
How much silage to conserve
The optimum level of conservation on a dairy farm will depend on the balance between animal requirements and pasture growth, with any surplus being available for silage production. Management changes on the farm, such as increased stocking rate, changing calving time, applying N fertiliser, and feeding supplements, can influence the availability of a surplus (see Figure 1.6).
A balance is needed between under- harvesting and suffering reduced pasture quality and utilisation, and over-harvesting and restricting cow intake.
The most appropriate way to decide the proportion of the farm that should be cut for silage is to estimate average animal requirements and pasture growth rate over the period of surplus pasture growth.
Pasture growth in excess of animal requirements can be targeted for silage (see examples above) — in this case an increase in stocking rate should be considered (see Figure 1.4).
As paddocks are dropped from the grazing rotation, monitoring should continue to adjust animal requirements and actual pasture growth rates for seasonal conditions.
Silage covered for storage
Conclusion
Silage can be used to increase dairy farm profit if it is integrated into the dairy system, if silage production is properly managed to guarantee a high-quality product and silage losses are minimised.
Where pasture is the cheapest source of forage, only genuine surpluses should be harvested. A predictive tool such as a feed budget should be used to estimate the area of the farm that can be cut for silage.
The following series of questions need to be addressed:
- What is the business goal? How much milk does the farmer want to produce?
- What is the current feed supply?
- What is the deficit in feed supply?
- How much of this feed deficit can be covered by home-produced silage? Note that silage is only a means to an end (more feed) and there are other feed options, which may be cheaper.
- If there is still a feed deficit can silage or forage (to make silage) be purchased nearby?
6. What is the cost of production for the new system? Taking account of all variables, labour and overhead expenses, what is the total cost/litre milk?
7. Compared to the milk price, is it profitable? This same approach should be used to assess any proposed change to the production system.
