Environmental awareness and the occurrence of erosion will promote increasing use of crops such as lucerne for feeding animals. A further advantage of legumes is the ability to fix nitrogen effectively in symbiosis with Rhizobium bacteria. This nitrogen can be utilised by a cash crop such as maize to give higher yields.
The effective conversion of lucerne into high quality meat and milk by ruminants will increasingly play a key role in providing food to a growing South African population. Increased consumer-choice of free-range poultry and pigs will also offer economic advantages to the producer who is willing to utilise possible alternative marketing channels, where a premium system is in operation.
The veld in those areas with cold winters and high summer rainfall (sourveld), cannot supply quality grazing in winter, and energy and protein needs especially are a problem on natural grazing. The production and harvesting of lucerne is therefore aimed at making high-quality silage and hay to provide for animals’ needs through the winter.
Monoculture of crops creates many problems, for instance, more fertilisers must be applied to achieve a satisfactory harvest. Annual cultivation of the soil also lowers the physical and chemical quality of the soil.
Input costs increase and there is a buildup of diseases. The inclusion of lucerne in a rotation system acts against these negative effects. Rotation is not only the rotation of annual crops, and to prevent the negative effects of annual cultivation it is necessary to utilise perennial crops such as lucerne. Perennial crops in a rotation system are known as ley-crops.
Ley-crops are usually fodder crops and cannot be compared with cash crops such as maize. Thus the area placed under a ley-crop must not be so large that the farmer suffers financial loss because of it.
The following factors are important for the successful establishment of a ley-crop:
Animals which are used in SA to utilise lucerne directly are usually animals that are in production such as weaned lambs, ewes with lambs at foot, milk cows and young oxen (steers). Their nutritional requirements consist of sufficient feed for maintenance, as well as production of meat and milk. By replacing low quality feed with a crop such as lucerne, the amount of concentrate needed in the rations can be reduced.
Good potential yield combined with high protein, energy and mineral content, make lucerne an economical source of nutrients.
Grazing of lucerne by sheep and cattle
The unpredictability of weather patterns in SA, as well as the timing of the natural mating season for sheep and cattle, results in increased need for feed during September to October; natural grazing being at its poorest when the lambs and calves are born.
Grazing systems where the early spring growth of lucerne is utilised by animals with lambs/calves at foot, are common. In other systems, where warm season grasses such as Eragrostis curvula (oulandsgras) are planted, lucerne is an important source of feed for animals during midsummer when warm season grasses are less productive due to seed production. If the lucerne produces maximally during the growing season, it is also possible to make hay or silage.
This diversity of uses of lucerne makes farming much less risky. Should the stand diminish to less than 10 plants per square metre, the land will no longer be sufficiently productive to be economical and the lucerne must be ploughed out.
Direct grazing on the land reduces costs. About 40% of the cost of manufacturing hay is linked to the costs of machinery and tractors for the manufacturing process. Recycling of nutritional elements, especially phosphorus, also reduces fertiliser costs.
Certain cultivars are specifically developed to withstand grazing. These usually are also resistant to diseases and pests. To increase yield, quality and lifespan of the lucerne, a rotational grazing system is recommended for cattle. It is generally recommended that a camp should not be used for longer than a week. This length of time is actually very flexible, but the use of regrowth from the crown must be prevented. It is important that lucerne should not be grazed for longer than 10-12 days maximum.
It is also important that the carrying capacity should be sufficiently high that available lucerne is grazed off within 10 days. This can be calculated by determining the dry matter (DM) available to the cattle in a specific camp.
Animals take in about 2.5-3% of their own liveweight of dry matter per day, so that, for instance, an animal of 300 kg will eat 9 kg of dry lucerne.
The intensity of grazing will determine the number of camps. With an intensive system and a high stocking rate the growth can be removed by the animals within a day or two. Under local conditions a 5-6 camp system is recommended. The time needed before a camp can be used again is determined by factors such as growing conditions.
During times of rapid regrowth, a camp can recover for re-use within four weeks, while under less favourable conditions, six weeks will be necessary. It is recommended that the period of absence should be between 42 and 60 days. Special attention must be given to newly-established lucerne. The plants must be well-established before they can be grazed.
It is recommended that the early growth be used for hay, to prevent damage to new seedlings. Lucerne must be grazed low, as this will stimulate regrowth from the crown and at the same time suppress weeds.
In areas such as the Highveld with cold winters, where lucerne may be killed by frost, it is important that about 20 cm growth be left to protect the crown through the winter. During this time, root reserves will be replenished, which will result in good regrowth the following spring.
The carrying capacity of lucerne varies from season to season, but on average 4-5 large stock units/ha (LSU/ha) can be kept through the growing season.
A LSU can be defined as an animal of livemass 450 kg. Changes in stocking rate depend on the productivity of the stand, the needs of the animals, experience in pasture management and the level of risk that a meat-producer is willing to carry. The productivity of beef cattle will increase if the lucerne is supplemented with grain.
Under normal circumstances, a supplement of 1.8 kg grain/LSU will supply the necessary energy for maximum production. These grain supplements are often used as carriers for additives to prevent bloat.
The utilisation of lucerne by sheep is much the same as for cattle. It has been found that merinos and mutton merinos, for instance, have less bloat than other sheep races. Chronic bloat occurs in some individuals which should preferably be removed from the flock. Sheep utilise lucerne less efficiently than cattle because they have a different method of taking plant material into their mouths.
Sheep are more selective and tend to avoid eating the the stems. Because of the presence of apical dominance, it would be advantageous for the farmer to cut these stems, and so encourage regrowth from the crowns.
Although sheep are lighter than cattle, the occurrence of soil compaction is still a substantial problem. If soils have a high fine-particle fraction, the compaction of the soil surface may create difficulties. Breaking up of clods with implements such as rippers is a common practice which allows water and oxygen to infiltrate to the roots.
Where lucerne is established solely for grazing by sheep, it should be sown in rows. Sheep will walk in the areas between the rows and, in this way, damage to the crowns can be prevented. Because of the advantages of by-pass protein, it is necessary to supplement with heat-treated soybeans, fish or grain products.
This will especially increase production of fat lambs, as well as the milk production of ewes with lambs at foot. An average daily gain (ADG) that might be expected from lambs on lucerne is 160-200 g/lamb/day.The average carrying capacity is usually determined by rainfall – 25 lambs/ha can be carried during the growing season with a rainfall of 800 mm/yr, while under irrigation 50 lambs/ha would be reasonable.
N.B. Never allow sheep to be covered when on lucerne that has been damaged by insects, hail or mechanical damage.
The plants give off hormones which influence the ovulation cycle of the sheep. The fertility of the ewes drops and leads to a lower lambing percentage.
Feed quality influences the milk producer through its effect on milk production, feed costs and animal health. The use of lucerne for milk cows has risen sharply in the past thirty years. By replacing low quality feed with high quality lucerne in the feed of milk cows, there is a saving on concentrates. This raises the profit margin of the milk producer.
Because of the growth cycle of lucerne, it is important that a producer be aware that its quality differs according to growth stage.
Co-ordinating feed quality with the needs of dairy cows
Nutritional requirements of milk cows depend on age, body size, reproductive phase and level of milk production. The most efficient utilisation of lucerne is its maximum inclusion in a ration which provides for the nutritional needs of the various classes of animals. Calves from 2 weeks to 3 months old can use high quality feed to advantage.
Their rumen is not yet fully developed and because of its limited capacity, the amount of fibre intake must be restricted. It therefore recommended that lucerne used for this class of animals should have a crude protein content of >18% and less than 42% NDF. Lucerne should preferably be given as hay, but haylage can also be given. Silage with its high moisture content should be avoided, as it will restrict intake.
Replacement heifers 3-12 months old have complete rumen development and capacity to utilise fibre which will supply a proportion of their needs. The protein requirements are reduced because of the increased capacity of micro-organisms in the rumen. Lucerne with 16-18% crude protein and NDF of 41-46% can be fed to these animals.
Replacement heifers 12-18 months old have a well-developed digestive canal and can get all their nutritional requirements from lucerne containing 14-16% crude protein with an NDF of 45-48%. Replacement heifers older than 18 months and dry cows can utilise lucerne of low quality.
Feed with a crude protein content of 12-14% and NDF of 48-52% is adequate. Feeding high quality lucerne before calving can lead to milk fever because of the high calcium content of lucerne. These facts make it clear that it is necessary for a milk producer to have lucerne chemically tested.
Where lucerne is directly grazed, milk cows must only be allowed to take 50% of their DM needs from lucerne.Grazing also follows a rotational grazing system. A possible system for milk producers would include the following:animals in milk should use about 50% of the lucerne available in a rested camp, after which dry cows and replacement heifers are put in to use the lower quality grazing left. Low quality hay with a high fibre content can be fed to animals if their butterfat drops too low.
In South Africa the climate is such that winter drought is normal in the summer rainfall areas.
Summer droughts in these areas are also a factor, and the making of hay and silage reduces the risk to the producer by offering an alternative to grazing. Furthermore, it gives the lucerne producer the facility to accumulate fodder that will keep its nutritional value, to sell it and to transport it more easily.
Ruminants live in symbiosis with micro-organisms, and feeding hay in winter changes normal rumen activity. Where poor quality silage is given the situation arises that especially milk cows develop an intense need for dry roughage.
The erecting of wire fences and the restriction of the natural movements of animals, especially browsers such as kudu, combined with the increasing role of ecotourism in farming, has induced farmers to feed especially kudu through the winter months. This feed is usually in the form of hay.
Wastage of leaves can be prevented by feeding lucerne in the form of feed pellets. This also simplifies storage. Hay and silage as a resource for the farmer. Under normal conditions hay for sheep and goats is milled with a hammermill. This prevents wastage and the eating only of the more palatable leaves.
The use of a feeding trough prevents small stock from wasting the milled material. Sheep and especially goats are inclined to scrape at feed with their front hooves to get at more palatable parts. The use of silage for sheep and goats is not recommended.
Several experiments in SA have shown that intake is limited and that the strange taste and high moisture content of silage reduces production. For animals such as cattle and horses which do not waste hay, the bales can be fed on the ground, and made available to the animals as long hay.
Most horse farmers prefer to use hay nets, while milk farmers rather feed long hay in troughs.This reduces contamination and increases intake. If hay for milk cows is milled too fine this can lead to low butterfat.
Where milk cows are fed silage, the intake is normally less than with hay. The farmer must thus make sure that sufficient time is allowed for the animals to take in enough feed.
This will save on expensive energy feed. Silage is usually fed directly to milk cows from bunkers.
For making high-quality silage: facilitate preservation and reduce losses.
Cutter Bar Mower
Cuts lucerne at a given height. Problems may be experienced if the lucerne has lodged.
Rotary Mower
A vacuum is created which lifts the lucerne and then cuts it evenly. Very little wastage.
Crimper
Bruises the lucerne stalks and so shortens the drying time.
Hay Rake
Lucerne is raked into windrows, to speed up drying and at the same time retain a desirable green colour.
Tedder
By turning the lucerne over it ensures that wet lucerne is quickly dried.
Small Conventional Baler (rectangular baler)
Facilitates handling of the hay.
Round Baler
Ideal where the farm is mechanised and where labour problems are experienced.
The utilisation of fresh chopped lucerne which has been harvested with a forage harvester is very labour intensive and is rarely used.
It is, however, used in feeding-pens and in this way the loss of leaves, and hence of quality, is kept to a minimum.
Bloat and consequent stock losses occurring on grazed legumes are often given as the main reason why these pastures are not included in a fodder flow programme.
The economic loss suffered by a producer by excluding legumes from a feed flow program are higher, however, than the use of highly productive, well-adapted and properly managed legumes.
Bloat is usually associated with animals grazing standing lucerne, to a lesser extent with lucerne hay and apparently not at all with silage and haylage.
It is an interesting fact that bloat often occurs in specific animals in the herd, and these animals can be used as indicators of potential bloat danger of a legume.
Bloat is an acute digestive dysfunction in ruminants, where gas formed by microbial fermentation in the rumen builds up and cannot be removed by normal means.
The increased pressure causes blood circulation and respiratory problems, which may result in the death of the animal.
With lucerne, the greatest danger of bloat occurs when the stand is in a vegetative phase, but drops to low risk whenever the lucerne enters the reproductive (flowering) phase.
Much research has already been done to identify the foam-forming agents.
Because the foam in the rumen is a complex arrangement of surface-active substances and other material, it is no longer attempted today to identify a single substance (e.g. saponins, or fraction I or II proteins) which may lead to bloat.
Legumes which do not cause bloat (mostly tropical and sub-tropical species) usually contain condensed tannins. Because a temperate crop such as lucerne does not contain tannins, it is possible that it may be made safe by introducing the genes for tannin-production.
The following main guidelines are often recommended:
The prevention of bloat by the use of anti-bloat substances and dosing with plant- or animal-fats is only a short-term solution. The full solution will only be achieved when it is determined what chemical component(s) or property of the plant causes bloat.
This would then make it possible for plant breeders to eliminate bloat problems from lucerne.
