Lucerne is a high quality feed that will produce large quantities of wool, milk and meat in grazed systems. Sheep and cattle production can increase by 10-50% if lucerne is included in grass pastures.
Beef production
The liveweight gain from grazing lucerne ranges from 0.6-1.2 kg/head/day, compared with the daily liveweight gain of cattle grazing high quality oats of around 1 kg/head/day. Taken over the whole year, lucerne pastures would be expected to increase the liveweight of cattle by 0.7 kg/head/day at perhaps twice the stocking rate, compared with 0.5 kg/head/day from cattle grazing a sown grass such as buffel grass.
Strategic use of lucerne in breeding enterprises will also increase the conception and calving rate. Higher weight gains at the same time as higher carrying capacities and reproduction rates will increase the rate of turnoff of finished cattle each year. Without lucerne, cattle will take an extra year to finish.
Intensive rotational use of lucerne is excellent for the management of cows and calves. The system involves grazing cows and calves through a series of 6 to 10 small paddocks. It is particularly effective if irrigation can be applied to maintain production by the lucerne. To maximise the benefits, cattle should have access to roughage, either as grass or crop stubble. Used in this way, lucerne can be effective in carrying a cow and calf on 0.5-1 ha on a year-round basis, although the carrying capacity will always be determined by dry matter production, that is, driven by seasonal rainfall.
Dairy cattle
Strip grazed winter-active lucernes, grown under irrigation, are productive options for dairy farmers. These are a cheap protein source, and their relatively low energy levels are readily supplemented with concentrates such as grain. Dairy cows producing 10 L/day on summer grass or crops should increase their production to 14-15 L/day on lucerne.
Sheep
In the southern border region, lucerne systems, stocked at 6-8 sheep/ha, are being used with success to produce prime lambs. Higher sheep-carrying capacities are achieved in southern Australian environments receiving more reliable rainfall.
Under irrigation, well-managed lucerne stands have successfully carried more than 80 dry sheep equivalents per hectare from October to May.
Anti-nutritional factors
Bacterial posthitis (pizzle rot)
Wether sheep tend to suffer more pizzle rot (bacterial posthitis) when grazing lucerne than when grazing grass pasture. This is caused by the higher nitrogen content in the urine of sheep grazing lucerne and can be reduced with a testosterone injection and by providing stock with access to dry grass.
Enterotoxaemia (pulpy kidney)
Pulpy kidney in cattle and sheep is also induced by the high nitrogen content of the urine and can be confused with bloat. Vaccinating with five-in-one or seven-in-one vaccines can prevent pulpy kidney.
Bloat
Bloat occurs when stable foam, produced from soluble proteins that occur in lucerne, develops in the rumen of cattle and sheep. Legumes containing condensed tannins do not cause bloat as these compounds prevent the development of the stable foam. The loss of stock to bloat is the greatest limitation to the sowing of larger areas of lucerne for grazing.
This risk of bloat is confined to the extensive beef and, to a lesser extent, sheep-grazing industries. In the more intensive dairying and beef enterprises the bloat risk is lower as cattle are more easily observed and moved on and off pastures in accordance with the risk. Sheep are not as susceptible to bloat as are cattle.
The risk of bloat can be alleviated by a number of managerial practices that may be applied singly or in combination, and by using anti-bloat agents.
Management options for bloat minimisation
• Ensure that cattle are not hungry and/or stressed when they enter lucerne stands. This reduces the risk of cattle gorging themselves on the new lucerne pasture.
• Feed hay or other conserved fodder or grain during times of risk. Place bales of hay near the water points. If possible, locate water points in grassy areas in the paddock.
• Graze lucerne continuously during the time of greatest bloat risk (spring), and then revert to rotational grazing for the remainder of the year.
• In a mixed sheep and cattle enterprise, graze sheep on the lucerne pastures during the period of greatest bloat risk in spring, while providing non-bloating fodder crops or pastures for the cattle. During the remainder of the year, allow the cattle to graze the lucerne.
• Remove cattle from the lucerne if they show symptoms of bloat. However, be careful in these situations because moving cattle that are showing bloat symptoms may further aggravate their problem. If stock are to be moved, they should not be moved far. If the bloat symptoms are extreme, the cattle should not be moved.
• Avoid grazing cattle on young and succulent stands of lucerne. Graze when the stand is mature and in flower.
• Sow lucerne with grass. A sward with about 10 plants/m2 mixed with grasses provides a ‘safer’ pasture at times of high bloat risk.
• Make hay from the lucerne stand rather than graze it at times of greatest bloat risk.
• Identify the most bloat-susceptible animals and graze them on pasture with a lower bloat risk.
• Pulpy kidney (enterotoxaemia) is often confused with bloat. Vaccinate all animals against pulpy kidney with five-in-one or seven-in-one vaccines before they graze lucerne. It is essential to give two vaccinations within 28 days before they start grazing lucerne because the first alone will not supply sufficient protection. It is also important to store the vaccine in a cool place and to administer it with care, ensuring that all stock receive the correct dosage. Some farmers vaccinate their stock with more than one course each year.
Using anti-bloat agents for bloat minimisation
Anti-bloat agents are additives that are supplied as part of the animal’s daily diet to prevent the occurrence of bloat. Those used most frequently are bloat oils and detergents (pluronics). These additives either break down, or prevent, the build-up of the stable foam in the rumen.
The main difficulty with using anti-bloat agents is getting the chemical into the animal. Several methods are used, including:
• Direct drenching with bloat oil, painting bloat oil high up on the nearside flank, or mixing anti-bloat compounds (including monensin) with hay or grain. These are applied, or fed in the bail, to dairy cattle, before they are placed on lucerne pasture each day.
• Spraying anti-bloat compounds on lucerne pasture. An amount, derived by multiplying the daily dose for each animal, by the number of cattle to be fed, by the number of days they will graze the lucerne, is sprayed on the strip before the cattle are placed on the feed. It is one of the faster methods of minimising the risk of bloat, but is only suitable with strip grazing and in dry weather.
• Adding anti-bloat compounds to drinking water. Water meters with dispensers are used to regulate the amount of anti-bloat compound to be added to the drinking water. Topping up tanks or troughs daily is an alternative to metering. The method is not suitable where stock have access to untreated surface water in the paddock, and the effectiveness is also reduced on cold days when little water is drunk.
• Feeding anti-bloat blocks. Commercially available anti-bloat blocks can give excellent results, especially in wet weather or when there is surface water available to cattle. However, blocks tend to be expensive and there is no way of controlling intake. There is no guarantee that all stock in the herd will eat the block.
• Feeding cottonseed. This is a concentrated feed that improves the weight gain of cattle, which, through its oil content, may assist in controlling bloat.
• Administering anti-bloat capsules orally into the rumen. These contain the growth promotant monensin (or rumensin) and provide protection against bloat for 100 days. The capsule is not guaranteed to eliminate bloat totally, but reduces the bloat risk associated with unrestricted grazing on lucerne. The cost of the capsule should be offset by the additional weight gain achieved by improved feed conversion through feeding monensin.
There are a large number of different products registered for use as bloat control agents. For further information regarding the use of these products check with the registered suppliers of each product.
.
