| Calliandra calothyrsus - Production and use: A Field Manual |
Rob Paterson, Brian Palmer, Max Shelton, Roger Merkel, Tatang M. Ibrahim, Rodrigo Arias, Kahsay Berhe, and A. N. F. Perera
Although the genus Calliandra includes a number of species that may have potential value for animal production, assessment of Calliandra as livestock fodder has been limited to a single species—C. calothyrsus. Under favorable conditions, C. calothyrsus grows rapidly and can play a useful role in a number of animal-production systems.
Like many other tree and shrub fodders, C. calothyrsus is rich in protein, but relatively poor in metabolizable energy. The edible fraction normally contains 20 to 25 percent crude protein, which makes it appropriate for use as a protein supplement for animals that are kept on a basal diet of grass or other poor-quality roughage. Its use should be limited, however, to a maximum of about 30 percent of the total diet on a dry-matter basis because higher levels are not fully utilized.
Estimates of digestibility vary widely, ranging from 30 to 60 percent or more. Oven-dried samples usually give poor digestibility levels, whereas fresh samples are normally at the higher end of the range. Sun-dried and freeze-dried samples tend to be intermediate between these extremes.
Although information is limited, animal production appears to show some correlation with laboratory results on digestibility: fresh C. calothyrsus fodder has given good liveweight gains in growing animals and good milk production in lactating cows, but dried fodder has given poor production levels. For this reason, C. calothyrsus should be fed fresh: conservation of leaf meal is not recommended. The leaves are known to contain high levels of tannins (twice as high as Leucaena, for example), and this may account for the fodder's low digestibility.
No matter how good a fodder looks in the laboratory, it is of no benefit to livestock if it is not eaten. Most experience shows that C. calothyrsus is well accepted by both large and small ruminants, particularly after a short period of adaptation. In some instances, however, cattle have been reluctant to eat it. Differences in fodder acceptability may be related to provenance, environment, or to an interaction between the two.
Alternatively, as with many tree fodders, it may simply be that animals require an adaptation period to become accustomed to the fodder before it can be used successfully as one component in a normal feeding regime. Further research is needed in this area. Meanwhile, it is advisable to screen a range of provenances when introducing C. calothyrsus as livestock fodder, not only for agronomic characteristics but also for acceptability. Certainly, provenance evaluation should precede any large-scale extension program to promote establishment of the trees on farms.
Although C. calothyrsus has proven quite resistant to pests and diseases in most areas where it has been tested, there is always a potential danger in placing too much reliance on a single species, or worse a single provenance of a species. For this reason, it is recommended that farmers plant C. calothyrsus along with other useful fodder species, such as Leucaena leucocephala and Sesbania sesban. Each tree has different strengths and weaknesses, and farmers will benefit from planting a variety of complementary species.
Animal feeding regimes
Two principal production systems can be used to raise livestock with C. calothyrsus as a feed supplement: a cut-and-carry system or direct grazing. Although the conservation of C. calothyrsus as leaf meal is not recommended, a deferred-feeding technique can be used with either system that involves accumulating leaves on the tree during the growing season and harvesting these in the dry season when the quality and quantity of the basal diet fall to low levels.
Under a cut-and-carry system, trees are grown to a convenient height with judicious pruning. The regrowth is then cut periodically and fed to livestock kept elsewhere on the farm. When the fodder is lush and growing rapidly, animals will consume the soft green stems up to a diameter of about I cm. When plant growth is slower, however, the stems become lignified at a smaller diameter, and livestock may limit their consumption to stems of about 0.4 cm or less. After the animals have consumed the leaves and small stems (edible fraction), the remaining sticks can be dried for use as cooking fuel. Trees are cut no lower than 30 cm above ground, but otherwise cutting frequency is more important than cutting height to ensure maximum tree productivity. To optimize the fodder's nutritive value, trees should be cut when they carry about 100 cm of regrowth. At this stage, the edible fraction is about 50 to 60 percent of total biomass. Under most conditions, such a cutting regime allows four to six cuts per year.
There is little information about the use of C. calothyrsus in direct-grazing systems. The wood is fairly brittle, and branches may be broken during browsing. Furthermore, if the animals chew the bark from the trunks, the trees may die. Nevertheless, positive results have been reported in North Queensland, Australia from continuous direct grazing over a two-year period (Palmer and Cooksley, personal communication). Calliandra calothyrsus was direct seeded into an established pasture of Brachiaria decumbens. The planted rows were 2 m apart with 50 cm between trees within rows. The stocking rate was 5 animals per hectare. The C. calothyrsus appeared to benefit from high stocking rates that prevented the trees from growing too tall. The trial site has a mean annual rainfall of 3399 mm, soil pH of 5.3 and aluminum saturation of 11%. While it would be a mistake to place too much reliance on a single experience, several trials have shown that C. calothyrsus can tolerate frequent and severe defoliation. It therefore seems likely that direct grazing may be possible, although further work is required to identify optimal utilization systems (Palmer and Ibrahim 1996).
Calliandra calothyrsus may also play a useful role in the production of non-ruminant livestock. Although there is little information on productivity levels, there are reports from Vietnam that C. calothyrsus is used for feeding fish in small ponds. The fodder can also be fed to rabbits in limited quantities as part of a mixed diet, and the addition of small amounts of leaf meal to the diets of laying hens (up to 5 percent on an as-fed basis) will produce a strong color in the egg yolks without any negative effects on egg yields or feed-conversion ratios (Paterson et al. 1996).
Fodder production systems
Volunteer stands. In Indonesia, where C. calothyrsus has been naturalized, trees are now found as volunteers in woodlands, along roadways, and in other sites. Farmers collect the foliage and use it to feed their livestock. Under such conditions, tree productivity varies widely depending on plant populations, soil fertility, cutting frequency, and other factors.
Linear plantings. Calliandra calothyrsus may be planted in single or multiple rows along farm boundaries or on contour bunds, terrace risers, or similar sites. In many instances, theses niches can be utilized for tree production without causing any adverse effects on adjacent crops. Within rows, trees are usually spaced 40 to 50 cm apart. Yields vary widely depending on climate, soil fertility, and other factors. At one site in sub-Saharan Africa, trees that were more than two years old produced annual yields of edible forage in the range 3 to 5 kg dry matter per meter of row (Paterson et al. 1996).
Block plantings. When grown in blocks, C. calothyrsus is usually planted at a spacing of I x I m or 2 x 0.5 m, although these distances may be adjusted to permit the use of machinery. Annual dry-matter yields of edible forage are frequently in the range of 3 to 8 t/ha.