Mulberry . A tree or shrub traditionally used to feed silkworms in different countries. It belongs to the order Urticales, family Moraceae and genus Morus. The best-known species, Morus alba L. and Morus nigra L., appear to have originated in the foothills of the Himalayas . As a fodder, it has excellent bromatological characteristics. It has crude protein contents of over 20% and in vitro digestibility of dry matter of over 80%.
Scientific name
Morus Alba L .
Common names
Mulberry, white mulberry, common mulberry.
Origin
Native species of China .
Chemical composition
The DM content of leaves and other foliage components of mulberry is high compared to that of grasses traditionally used for animal feed . In Costa Rica, DM levels of between 25 and 32% are reported for leaves; between 23 and 29% for tender stems and between 24 and 45% for woody stems. In plantations of three varieties of mulberry planted at 0.40 m between plants and 1 m between rows (25,000 plants/ha), in three ecologically different sites in Costa Rica and with various levels of fertilization, it was found that the DM content of the leaves and of the edible fraction of the stem was much more affected by soil and climate conditions (site) than by fertilization levels and there were no substantial differences between varieties. In the woody stem, the differences between sites were even more notable and the values varied between 27 and 48% DM. The little effect of the fertilization level on the DM content was also reported in a plantation in which different levels of goat manure were applied to the soil.
Mulberry leaves are characterized by their high levels of crude protein and in vitro digestibility of dry matter compared to the most commonly used feeds for ruminants. In Central America, CP contents between 15 and 25 % and IVDMD contents between 75 and 90 % have been found, which indicates a quality equal to or superior to that of commercial concentrates . The non-lignified stem (tender stem) also has a good bromatological quality, with values of 7 and 14 % for CP and 56 and 70 % for IVDMD .
As in the case of DM, the PC content and IVDMD are similar between varieties and are not significantly affected by the level of fertilization or by the frequency of pruning. However, in the works mentioned above, a marked effect of the site is reported, given the different edapho-climatic conditions of each one.
In Paquera, located on the Pacific coast of Costa Rica , where there is high luminosity and high temperatures, the PC and IVDMD of the leaves are reduced (15.1 and 71.5%, respectively) compared to those of higher sites that have more cloudiness and lower temperatures (24.8 and 74.9%, respectively), such as Coronado and Puriscal located in the mountainous areas of Costa Rica .
In a proximal analysis work with the Kanva-2 variety of M. alba, high protein contents (29.6%), ash (7.5%) and nitrogen -free extract (50.0%) were also found. Likewise, low levels of crude fiber (10.1%) were reported. In the same work, the type and quantity of amino acids present in mulberry leaves were determined.
Animal response
When comparing mulberry foliage with concentrate fed as a supplement to grazing cows, a similar level of milk production (13.2 and 13.6 kg/animal/day, respectively) was obtained at the same levels of DM intake (1% of LW), which was higher than that obtained with grazing alone (11.3 kg/animal/day). The use of mulberry in the diet did not affect the fat, protein or total solids content of the milk, but improved the net benefit compared to concentrate (US $3.29 vs 2.84, respectively).
Biologically attractive weight gains have been obtained in cattle using mulberry leaves as a supplement. In the humid tropics of Turrialba, Jersey x Criollo replacement heifers were supplemented with mulberry under grazing conditions, and although no statistically significant differences were detected, the weight gain was higher (550 g/animal/day) than that observed when supplementing with concentrate (410 g/animal/day).
In a 3-year evaluation, in an agroforestry module with goats fed only similar amounts of kinggrass and mulberry (3.0% of LW), about 900 kg of milk/animal/300-day lactation was reported. This equates to an average production of 3.0 kg/animal/day and 4.1 kg/animal/day at the beginning of lactation. Feed came from an area (1 100 m2) of mulberry and grass associated with poró (Erythrina poeppigiana), fertilized with animal manure, associated poró foliage and feeder residues. During the third year, milk production from the module was 5 kg/day, which equates to 16 500 kg/ha/year. The cash flow study for the financial analysis showed a benefit/cost ratio of 1.27, 1.39 and 1.45 for each year, respectively.
One of the most serious problems in livestock farming is the drastic decrease in the availability and quality of pasture during drought. Alternatives include forage silage made during the rainy season for use in drought. However, traditionally silages are made from tropical grasses that have a high level of fibre and few soluble carbohydrates, which affects fermentation and results in low-quality material. Due to its low fibre and high level of carbohydrates , mulberry foliage can be ensiled without additives; this silage shows a lactic fermentation pattern, few losses in CP (between 16 and 21% of CP) and maintains between 66 and 71% of IVDMD, indicators much higher than those of silages made from tropical forages.
By using whole-plant mulberry silage without additives as a supplement to confined bulls fed a basal diet of elephant grass, weight gains of 600 g/animal/day were obtained with a mulberry intake (dry basis) of 1.1% of LW. On the other hand, goats consuming silage as the sole diet showed an intake on a dry basis of 5.0% of LW and a yield of 2.0 kg of milk/animal/day.
Due to its high production capacity and the high concentration of minerals in its biomass, mulberry extracts a large amount of nutrients from the soil.
For this reason, emphasis has been placed on the use of organic fertilizers (manure and mulch) as a source of nutrients. Using a density of 25,000 plants/ha, more than 35 t of total DM/ha/year were obtained using goat manure as fertilizer, which represents 20% more than that obtained with the same amount of nitrogen from ammonium nitrate; in addition, a 10% increase in yields was observed between years for 3 years (Benavides et al., 1994). On the other hand, under humid tropical conditions and using poró foliage as mulch at levels equivalent to 0, 160 and 300 kg of N/ha/year.
Pruning
There is information on the effect of different pruning heights on dry matter production, but in some cases it is contradictory and in others too preliminary. Due to the influence that pruning height seems to have on the leaf/stem ratio, it is important to corroborate this aspect in new works and in different environmental situations.
In plantations intended for the production of forage for ruminants, pruning frequency has only been evaluated under humid tropical conditions. However, it is in the dry tropics where this factor may be more relevant. It is possible that under these conditions the frequencies within the year do not necessarily have to be regular, but rather determined by the rainfall patterns that exist at each site. In these cases the height of the plant may constitute a more objective criterion to determine the moment of pruning.
According to the literature, the number of main branches that are kept after pruning has a significant effect on biomass production. However, the known works in this regard refer to the production of leaves to feed the silkworm and there is no information on its application in plantations to produce fodder for ruminants.
One of the main problems of livestock farming in the tropics is feeding during the dry season. In this regard, it is advisable to carry out studies on the effect of pruning at the end of the rainy season on biomass production during the dry period, which would allow for the availability of good quality fodder.
Another problem that may limit the use of this species in large-scale systems is the lack of techniques to mechanize its harvest.
Forage cutting does not seem to present any problems in production systems with few animals, based on the use of family labour. However, in larger farms, methods of harvesting should be studied. It is also necessary to consider the problems related to the mechanized use of organic fertilizers , which may imply a higher production cost in such systems.
Sowing
Aspects related to the sowing season are also more relevant in dry tropical conditions than in climates with good rainfall. This has been little studied and possibly has an important effect on the establishment vigor (rooting) and survival of the seed used.
The influence of the sowing distance has been studied under bimodal rainfall conditions in Guatemala , where greater production has been observed with denser sowing. However, this type of work must be continued to determine the effect that it may have on the sustainability of production.
Of course, the spacing also depends on whether it is a monoculture or an associated plantation.
Based on field observations, it is possible to assume that mulberry cuttings, as reported for some leguminous tree species, can be planted lying down and at a shallow depth to take advantage of a greater number of growth points, save work and use less seed.
The development of sowing methods on slopes is of great importance, since it constitutes an alternative that allows a rational use of the soil and contributes to preventing or reducing the erosion problems that are becoming more serious every day in the region.
One of the greatest difficulties in small and medium-sized farms when trying to introduce forage areas is convincing producers to replace the land they dedicate to crops with areas for forage. In this case, it is highly recommended to evaluate associations of mulberry with the most common crops on the farm, which allow greater productivity per unit area and do not produce significant effects on traditional crops.
Fertilization
Undoubtedly the most limiting factor in mulberry production is its high dependence on soil nutrients. Therefore, in this work, emphasis was placed on aspects related to fertilization. However, there are still many alternatives to be evaluated, such as the use of other types of organic fertilizer and the association with nitrogen -fixing plants .
Although high yields can be expected with the use of chemical fertilizers, their application will be limited by price and the environmental impact they may cause. The association with tree or herbaceous legumes to use the foliage as green manure is an interesting alternative that should be evaluated, especially in the case of trees due to their role in nutrient circulation and soil retention.
Evaluation of species and varieties
In Central America there are several species or varieties of mulberry planted in different locations. However, no comparative study has yet been carried out on the advantages and disadvantages of each one, which would allow recommendations to be made for each climate condition and soil type. Improvement and selection work on mulberry appears to be very necessary, due both to its forage potential and to the existence of a large number of species and varieties.
Economic evaluation
Although there is some economic information for humid tropical conditions, it is necessary that the research work carried out on mulberry consider economic evaluation as a decisive element when defining recommendations for its use.