Once a forage crop is established, careful management is required to ensure it reaches its full potential and is fully utilised in its most productive and nutritious phases of growth.
Pests and diseases must also be managed to minimise their impact on productivity.
The grazing of fodder crops should be timed to occur when the plants are well anchored in the soil and at phases in the growth cycle when the plants are at their most nutritious. This will vary between plant species but is generally before the plant enters the reproductive phase and begins to hay off.
A well-considered grazing strategy is important in maximising the productive potential of a fodder crop as they can produce a large volume of feed over a relatively short period of time.
Grazing of fodder crops should occur at phases in the growth cycle when the plants are the most nutritious. This can be challenging due to the fast-growing nature of some forage crops and a grazing strategy should be developed to match feed demand with supply.
A well-considered grazing strategy is important in maximising the productive potential of a fodder crop. Fodder crops have the potential to produce large volumes of high-quality feed and if not carefully managed, this can easily become rank and lose nutritional value.
Grazing strategies include the use of:
- rotational grazing
- continuous grazing
- a combination of the above.
Describes the practice of rotating livestock through a series of paddocks, whereby the time the last paddock in the series has been grazed, the first has been rested allowing sufficient pasture growth for the paddock grazing sequence to commence again. Rotational grazing strategies are most effective when conducted at a high stocking rate or stock density and livestock should be moved before the feed supply in the grazed paddock is totally depleted. If livestock are allowed access to forage crops when hungry or empty, animal health issues can arise.
Crops should be stocked conservatively to allow plants to recover such that grazing can be maintained over the crops growing period. Supplements should be fed with some forage crops to stimulate rumen function and compensate for nutritional deficiencies.
Health and welfare
There are a few potential health and welfare issues associated with grazing forage crops. Some of these are associated with particular plant toxins e.g. the propensity for sorghum to produce hydrogen cyanide (HCN) during early growth and when moisture stressed. Others are due to physiological reactions within livestock such as acidosis, which occur when ruminants are suddenly exposed to large volumes of high-quality feed.
Producers should consider the following health and welfare strategies when grazing forage crops:
- Livestock should be introduced gradually to forage crops to allow the rumen to adjust to the new feed and avoid giving hungry livestock sudden access to forage crops.
- Roughage should be made available, usually as hay, to assist with rumen function and slow the passage of highly digestible feed through the rumen.
- Water should be freely available as limited water can also limit feed intake.
- In some circumstances, mineral supplements may be required to prevent metabolic or nutritional disorders.
- Producers should familiarise themselves with the potential animal health issues associated with each forage crop. This should be considered in selecting a crop that best suits the enterprise’s circumstances.
Forage crops can be grown for the sole purpose of fodder conservation. Fodder conservation can be a useful way to make the most of forage that is surplus to a grazing requirement. Forage crops are generally conserved as hay or silage, depending upon the crop and the intended use of the forage.
The timing of both grazing events and the cutting for hay or silage are critical to ensuring the quality and quantity of conserved fodder are optimised – generally earlier when the forage quality (digestibility or energy content) is highest.
Fodder is usually conserved as hay or silage. Some forage crops can either be grown exclusively for hay, or silage production or grazed before being set aside for fodder conservation.
Fodder conservation is an important tool for evening out peaks and troughs in feed supply in a grazing enterprise. Forage crops can play an important role in providing fodder that can be conserved for later use.
The fodder conservation process commences with the cutting of the crop. The timing of the cutting influences the potential quality or feed value of the hay or silage.
The crop should be at a phase in the growth cycle where vegetative growth and plant sugars are at or near their peak. This will ensure important feed attributes such as protein, digestible energy, dry matter percentage and digestibility are at their highest potential at the beginning of the conservation process.
Hay production is the most common fodder conservation practice. Most crops and pastures can be made into hay of varying quality. However, all successful hay making relies on wilting the cut pasture to a moisture or dry matter level where it is dry enough not to ferment but wet enough not to shatter when baled. This is usually at about 12-14% dry matter but varies according to bale size and shape.
If hay is baled with too much moisture it can ferment leading to heat generation, feed quality decline and a potential fire risk.
Rain presents one of the greatest challenges in making hay. Rain delays wilting, leaches nutrients from the cut forage and makes achieving satisfactory moisture levels difficult. Silage can be easier to manage if rain is expected as the ensiling process is undertaken at higher moisture levels and therefore less drying time is required.
Silage is made by ensiling or fermenting forage crops or pasture and generally produces better quality feed than hay. This is due to the reduced interval between cutting and conserving the feed when making silage – the longer the interval, the more the feed nutrients degrade.
As with hay, forage crops should be cut for silage at their most vegetative stage with no more than 20% of seed heads showing. This is then wilted to about 30% dry matter before being chopped and ensiled in an airtight environment such as a pit or wrapped in plastic.
The production and storage of silage relies on an anaerobic air-free) environment. This promotes the desired fermentation processes and inhibits undesirable processes and decay. It is critical that an air-free environment be maintained from the time the silage is made until it is fed out.
Vendor declarations, withholding periods and grazing intervals
If fodder is being produced for sale, a fodder vendor declaration or commodity vendor declaration (CVD) should be completed to accompany the hay when sold.
Producers must ensure that all withholding periods (WHP) and export grazing intervals (EGI) are observed when grazing forage crops that have been treated with chemicals.
Pests and diseases
Pests and diseases can damage forage crops if they are not dealt with soon after a problem is identified.
Forage crops should be inspected regularly, particularly during high risk periods such as late summer and autumn, for pests such as:
- redlegged earth mite
- plaque locusts
Diseases and deficiencies pose a similar risk to fodder crops as pests and should be monitored when checking crops for pests. Diseases can generally be classified as leaf diseases e.g. rusts, or root diseases (e.g. wilt).
Integrated pest management
Integrated pest management (IPM) involves using a combination of biological, physical and chemical control methods to control pests. As beneficial insects are a key component of IPM, the use of insecticides is minimised, but not excluded altogether.
The first step in IPM is for a producer to identify and understand the lifecycle of the pests and beneficial insects in their area. A plan can then be put in place to manage the populations of both beneficial and pest insects. This broader whole-farm approach to IPM should be considered when selecting the most appropriate forage crop for an enterprise.
Once a plan has been developed for a particular forage crop, careful and ongoing monitoring is then required to ensure that a favourable population of beneficial insects is maintained and pests are kept under control. Corrective actions such as slashing adjacent pastures to encourage beneficial insects to enter a forage crop or spraying can then be undertaken when pest numbers threaten to impact forage crop production.
Diseases and deficiencies pose a similar risk to forage crops as pests do and these should be monitored when checking for pests. Diseases can generally be classified as leaf (e.g. rusts) or root diseases (e.g. root rot).
Management for disease control should be both proactive and reactive. Proactive control begins with forage crop selection and takes into consideration paddock and disease history. If a particular disease has been a problem in the past, a forage crop that is resistant to that disease should be selected.
Reactive disease control involves managing outbreaks and may include strategic grazing and chemical application.