Topics on this page:

• Managing bloat
• Irrigation
• Haymaking
• Yields

Lucerne does not survive continuous, heavy grazing, especially by sheep. Persistence is improved by spelling, although this does not necessarily mean applying a rigid rotational grazing system. This is particularly so in systems grazed by cattle where a more flexible rotational system can be applied without prejudicing stand persistence. It is widely accepted that winter dormant lucerne varieties with low crowns are more persistent in grazed pastures than the winter active, high crown types, providing they all have appropriate levels of resistance to diseases and pests.

Nevertheless, well-managed stands of highly winter active varieties, which are more productive, have persisted for 3-4 years when grazed with cattle in Queensland.

Managing bloat

Bloat is a concern in extensive lucerne grazing enterprises, particularly with cattle, where animals are observed and managed infrequently. Sheep are not as prone to bloat as are cattle, although bloat management is advised. The attitudes of farmers to bloat are varied. Some fear losses but others manage bloat, believing that the benefits of lucerne offset the losses that do occur. In a recent survey of farmer/graziers in southern Queensland and northern New South Wales, losses ranged from 0-6% (mean 1.55%) with cattle and from 0 to 1.25% with sheep.

There are many management strategies that can be applied to minimise the risk of bloat, including the following:

•  Do not introduce hungry or stressed stock into lucerne pastures.
• Acclimatise stock to lucerne by giving them initial access for short periods only.
• Sow lucerne with grass or some other non-bloating forage.
• Place stock on mature lucerne pasture - some farmers graze after flowering.
• Feed roughage around watering points or ensure that animals have access to grass, preferably as they walk to water.
• Consider alternative whole-farm forage provision and grazing strategies during the period of greatest bloat risk (usually winter/spring), e.g. graze the lucerne pasture continuously or avoid grazing it at all at that time, cut hay instead of grazing but not in winter.
• Remove animals from lucerne pasture when climatic conditions suddenly change from dry to humid and rainy, or when stock show bloat symptoms.
• Use anti-bloat agents including:
  • bloat oils and detergents (pluronics) that are either sprayed on pasture, added to the drinking water or mixed with grain and hay
  • anti-bloat blocks
  • anti-bloat rumensin capsules
  • supplements with high oil contents that may act as anti-bloat compounds. Cottonseed is considered to have anti-bloating properties.

It is important when managing bloat, to eliminate the possibility of animals dying from pulpy kidney (or enterotoxaemia), a condition often experienced with animals grazing high protein forages. Many farmers believe pulpy kidney poses a greater risk to stock than bloat and that it is often confused with bloat. However, it can be managed. Animals can be vaccinated against pulpy kidney. It is vital that vaccination is carried out carefully:

• Ensure that stock do not graze lucerne until one week after receiving their second (or booster) dose of vaccine.
• Use carefully stored vaccine before its use-by date. Cool storage both before and after purchase is vital as heat and age of the vaccine may render it ineffective.
• Take care in the vaccination process that the correct dosage is applied. Careless application and faulty applicator guns will result in ineffective inoculation.

About 75-100 mm (0.75-1 ML) of water is required to produce 1 tonne of hay in a good lucerne stand. Therefore a crop producing 16 t/ha/year of hay will require a minimum of 1200 mm (12 ML)/ha/year of rain and irrigation. If rainfall constitutes 700 mm (7 ML/ha), the remaining 500 mm (5 ML/ha) needs to be applied as irrigation.

Heavy irrigations are preferable, with rates varying 50-100 mm/ha depending on soil type. Irrigations between hay cuts vary from one to three depending upon the irrigation rate, soil type and underground water tables. A steel probe gives a good guide to the depth of soil moisture. More refined moisture monitoring tools are now being developed for use in lucerne and other crops.

Haymaking and handling details are discussed in the DPI&F publications Lucerne Management Handbook (ed. Ken Bullen) and Haymaking (Bill Mills), available by contacting DPI&F on 13 25 23.

Lucerne stands persist longer if cut at the correct time. Cutting at 10% flowering has been accepted practice with growers of 'Hunter River' types, but is not a good indicator for most of the highly winter active varieties, which should be cut when the crown buds begin to elongate but before new generation shoots are long enough to be damaged by cutting.

Lucerne is usually baled at around 20% moisture content. However, time from cutting to baling can be reduced by the use of different hay curing additives, such as:

• Pioneer Hay Inoculant - a bacterial mould-inhibiting agent applied at baling time that allows hay to be more safely baled at around 25% moisture content
• Hay 2000 - applied to the hay at baling time, which is also a mould-inhibiting agent allowing hay to be baled at around 25% moisture content
• K-hay (potassium carbonate) treatment applied at cutting, which will assist the hay to dry in humid environments.

Growers contemplating use of such curing additives are advised to assess the acceptability of treated hay with their clients.

Irrigated stands will produce between 2-2.5 t/ha of hay per cut. Around 7-8 cuts a year can be expected from an irrigated crop, and 1-2 from a dryland crop, depending on the season. Winter-active varieties should provide an additional 1-2 cuts during the cooler months, but curing is usually slower in winter, exposing cut hay to increased risk of weathering. With field curing it is usual to budget for at least one cut/year being damaged by rain.