Jorge Benavides
Researcher
CATIE, Turrialba, Costa Rica
FORAGE TREES
Livestock production and natural resources
Numerous traditional land-use practices (deforestation, extensive and extractive grazing, lack of erosion control techniques, agriculture in unsuitable zones, etc.) result in alterations to ecological balance and in soil productive capacity (Garríguez, 1983; Jiménez, 1983; Heuveldop and Chang, 1981). Tropical grass yields and quality are affected by climatic factors (Minson and McLeod, 1970; Stobbs, 1975; Cubillos, Vonhout and Jiménez, 1975) and by land and capital limitations predominant in most small farms (Ávila, Navarro and Lagemann, 1982).
Apart from the socio-economic aspects, the later is related to the type of agricultural technology historically practised in Central America from the times of Spanish colonization. In pre-Colombian times, the great Pleistocene herbivores had disappeared (Jansen and Martin, 1982) and there were no domestic ruminants. There were only autochthonous deer, which are mostly browsers (Sands, 1983; Morales, 1983). The predominant vegetation was composed of shrubs and trees and, apart from maize, there were few members of the Gramineae family, without contributing much to feed the autochthonous herbivores (Jansen and Martin, 1982; UNESCO, 1979; National Geographic Society, 1992; Skerman and Riveros, 1992). This indicates that the natural vegetation looked very different then compared to how it does now.
Spanish colonial settlement implied the introduction of land use technologies imported from temperate areas, such as the plough and grasses to feed farm animals (Meza and Bonilla, 1990; Tosi Jr and Voertman, 1977). These technologies, still in use, have contributed significantly to the loss of natural soil cover and biodiversity. This has also prevented the rational utilization of forests aiming at questionable productivity in the medium and long term. In relation to traditional livestock keeping, "... it is little encouragement, for the grass pasture experts, to realize that there are more animals feeding on shrubs and trees, or in associations in which woody plants have a major role, than on true grass and leguminous pastures" (Commonwealth Agricultural Bureau Publication, No. 10, 1974, cited by Skerman, Cameron and Riveros, 1991). The establishment of agricultural areas in virgin land has been part of a process, that starts with cereal planting taking advantage of the high soil fertility right after the slash of the forest. Once this fertility declines, land is abandoned or destined to grazing, mostly extensive and extractive (Sands, 1983). Since the 1950s, more than 50 percent of forests have been substituted by migratory agriculture or by grasslands (Collins, 1990; UNESCO, 1979; National Geographic Society, 1992) which, in most cases, are in scattered plots belonging to small farms, or have low carrying capacity on large farms (Collins, 1990). In Central America, without large amount of inputs and labour, the productivity of grasslands cannot be maintained. This is partly due to invasion of autochthonous woody plants as to what - "... while man insists in keeping grassland, natures fights for establishing forests" (Skerman and Riveros, 1992).
The question then arises would have happened in the American tropics if, instead of introducing the plough and grasses, appropriate technologies aiming at a rational use of trees and shrubs had been developed? Apart from wood, could other products be extracted from forests to satisfy the demand of expendable goods demanded by the population? Research on forage trees and shrubs, in particular that on mulberry, aims to give a partial response to this question.
The above considerations, added to small- and medium-size farmers’ lack of access to appropriate production technologies; high population growth; and other aspects related to the socio-economic situation of Central America, indicate the necessity for novel solutions that will allow substantial changes to be made in current production practices. In this changing process, the development of technologies more suited to the ecological and socio-economic conditions of the region should play a decisive role in the generation of consumable goods in a sustainable manner and with a rational use of natural resources.
Trees and shrubs as feed for ruminants
The use of trees and shrubs for ruminant feeding has been practised among producers in Central America for decades. This empirical knowledge about forage properties of various species is of great value for science. In several studies to characterize production systems, producers report a large number of species for browsing and for cut-and-carry systems with animals in confinement (Ammour and Benavides, 1987; Arias, 1987). The more systematic recognition of these resources is the aim of the research on forage trees carried out in Central America, part of which is reported in this article.
Studies on the subject have been oriented towards valuation of trees and shrubsas a source of forage and their integration into ruminant production systems (Benavides, 1989). The focus has been on agroforestry and farming systems, and the aim has been to develop technological alternatives allowing more sustainable production and rational use of soil and forest resources.
In order to consider a tree or a shrub as forage, it must have advantages above traditional forages from the point of view of its nutritional value, its yield or its agronomic versatility. To qualify, these requirements are: i) nutritional content and intake that will allow animal performance improvements; ii) resistance to repeated pruning/harvesting; and iii) high biomass yields per unit area. Apart from these features, it is advisable to select native species to take advantage of their adaptation to the environment, and species that can easily be established with simple and inexpensive techniques (Benavides, 1991).
Data from producer surveys and the literature indicate the presence of woody forages in the humid tropics of the Atlantic coast of Costa Rica and in the Petén of Guatemala; in semi-arid areas near the south coast of Honduras and in the Dominican Republic; in the mountainous regions, with long drought periods and serious erosion problems, in the Pacific slopes of Costa Rica; and in zones with temperate climates above 1 000 m in the high plateaus of Guatemala and Costa Rica (Hernández and Benavides, 1993; Araya et al., 1993; Mendizábal et al., 1993; Godier et al., 1991).
Direct observation of animals eating has allowed to identification species that are particularly palatable and have high digestibility (in vitro) of the organic matter (IVOMD) and high crude protein (CP). These studies have permitted species without current use to be valued, together with others normally used for different purposes (Hernández and Benavides, 1993; Godier et al., 1991; Reyes and Medina, 1992).
The information provided by producers has also allowed simple and easy to implement agronomic management practices to become known. Examples are the woody forages identified in the western Plateau of Guatemala where, in most cases, propagation is carried out by vegetative means (stem cuttings) with which a faster biomass can be obtained compared with sexual seed (Ruiz, 1992).
The forage from most of these woody forages shows CP values two and three times higher than tropical grasses and, in some cases, even higher than commercial concentrates used to supplement ruminants. At the same time, the IVOMD is very high and comparable with or superior to that of concentrates. Two species of the Euforbiaceae family are outstanding in nutritional quality, Wide Chicasquil (Cnidoscolus acotinifolius) and Fine Chicasquil (C. chayamansa. Their leaves, with more than 30 percent CP and 75 percent IVOMD, are edible. Also outstanding in nutritive value are two species of the Moraceae family, mulberry (Morus spp.) and Amate (Ficus spp.) from Petén, Guatemala; two from the Malvaceae family, the Amapola (Malvaviscus arboreus) and the Clavelón (Hibiscus rosa-sinensis); Black Sauco (Sambucus mexicana) and Yellow Sauco (S. canadensis), belonging to the Caprifoliaceae family; and three species of the Compositeae family, Chilca (Senecio spp.), White Tora (Verbesina turbacensis) and Purple Tora (V. myriocephala). All of these have CP higher than 20 percent and IVOMD higher than 70 percent (Araya et al., 1993; Mendizábal et al., 1993).
Animal Performance
In intake trials, Poró (Erythrina poeppigiana), was the most studied species in the 1980s, with observed values higher than 4 percent with lactating goats (Benavides, 1993). In other work, acceptability has been sought in forage species growing in semi-arid lands, under forests and in secondary forests, which were identified by means of direct observation of grazing animals (Godier et al., 1991; Hernández and Benavides, 1993; Reyes and Medina, 1993).
Both Poró and Black Wood (Gliricidia sepium), are legumes characterized by high CP content, but with lower IVOMD (Benavides, 1991). In these cases, research has shown that energy supplementation significantly improves animal performance (Benavides and Pezo, 1986) and that starch sources give a better response than simple sugars (Samur, 1984).
With species with higher nutritive value, the highest milk yields have been obtained and a significant response has been observed when the foliage level is increased on grass-based diets. That is the case with Amapola and Mulberry, with milk yields in goats of 2.2 and 4.0 kg/d, normally only possible with commercial concentrates. With these species, intakes higher than 5 percent of body weight are reported. With mulberry foliage, increasing weight gains have been observed when raising its proportion in the diet (Rojas, Fuentes and Benavides, 1994; López et al., 1993).
Of the known technologies, vegetative propagation is the most used, since it shortens the establishment period, is easy to carry out and widely known by producers. Germination percentage exceeds 95 percent, when stem cuttings of mulberry and Amapola are used in humid tropical conditions (Araya and Benavides, 1992; Benavides, 1993; López et al., 1993a,b). With the Yellow Sauco, nursery planting of stakes and further transplanting seem to be the most suitable propagation method (Araya and Benavides, 1992). In some species it is possible to place stakes horizontally, obtaining several plants and sparing material (Esquivel, 1993). However, there are important variations among species, which are important to know before making a decision about which technique to use (Strehle et al., 1992).
The association of leguminous trees and grasses is a viable alternative with two modalities. In the first, the forage of both grass and tree is utilized. Results of an experiment under humid tropical conditions, using King grass (Pennisetum purpureum x P. typhoides) with Poró with no nutrient replenishment and all biomass removed showed that grass yields are not reduced by the presence of the tree, since tree pruning reduces competition for light. It was also found that digestible nutrient yields per area were triple compared with the grass alone. Nevertheless, in the short term for the grass and in the medium term for Poró, productivity declines because of lack of nutrient replenishment (Benavides, Rodríguez and Borel, 1989).
The other way is to utilize associated Poró foliage as green manure for the grass. In the humid tropics, grass yields improved when increasing amounts of Poró foliage were applied. At the same time, the sole presence of the tree, even without pruning, stimulated grass growth compared with grass in a monoculture without trees (Libreros et al., 1994a,b).
Traditionally in livestock husbandry, there is an unidirectional relationship between animals and plants, the first benefiting by obtaining the feed, but without contributing to its generation. In confined systems, it is possible to establish a two-way relationship, since most manure can be used as fertilizer. In this way a more balanced system can be established and the plants will benefit from the animal excreta. This particularly applies to those woody species and the best forage features. With their high biomass yields and without being able to fix nitrogen, they require high levels of fertilizer applications. In order to find a rational ecological solution, goat manure has been applied to Amapola and mulberry plantations. The yields have been 18 and 30 tonnes of dry matter per ha, respectively. With mulberry, yields increase over years (Benavides et al., 1993).
Of great importance, in sites with bimodal rainfall pattern, are tree-pruning techniques that allow abundant biomass production during the dry season. The effects of pruning at the end of the dry period have been studied. In the Dominican Republic, pruning of Black Wood (Piñon cubano or Gliricidia) in the months of October, November and December, in addition to stopping flowering, results in increasingly higher biomass yield during the dry period (Hernández, 1988). Similar results were obtained by other authors working with Amapola and Jocote (Spondias purpurea) (Rojas, Vallejo and Benavides, 1992).
To date, most of the technologies have been implemented in small farms and in goat production systems oriented towards family consumption. In these situations, in addition to the technological aspects, it is essential to know the economic viability of the alternatives developed, both at the station and on the farm. For the economic aspects, partial budget analysis of experiments; profitability analysis (flow and net income) of implemented technologies in pilot modules; and analysis of family benefits and flow and net income at the farm level have been used. The analysis, indicates that the application of forage tree technologies on the farm is profitable and contributes to improving family economy.
With dairy goats under a basal diet of grass, the use of Poró foliage and other agricultural by-products (e.g. reject bananas) as a supplement is more profitable than the use of concentrates, despite higher yields with the latter (Gutiérrez, 1985). Total cost of DM, from planting to feeding in some forage species nutritionally comparable with commercial concentrates, is lower (Rojas, 1992). This in part explains the high profitability of a dairy goat model at CATIE with goats fed exclusively mulberry and grass (Oviedo et al., 1994).
At the level of family subsistence units, high profitability has been found when family labour is not considered, even with animal reproductive problems present (Martínez & Froemberg, 1992).
Environmental impact of introduced technologies
Part of the research goals with forage trees is the development of planting techniques that allow soil conservation in erosion risk areas. At the same time, soil nutrient balance indicates whether there is a need to add a nutrient with a high extraction rate (Libreros et al., 1993).
Shrub species with high forage potential can also be used to control soil loss, since they can be planted at high densities, are perennial and can be associated with other crops. Over three years, in a site with a steep slope and serious erosion problems, two types of Amapola plantation were established (Amapola in high density, in contour lines associated with low grass and Amapola in more separate contour lines associated with maize) and were compared with a traditional maize crop (bare soil). Soil loss was much less in the Amapola plantations (Faustino, 1992).
MULBERRY
Background
Mulberry is a shrub or a tree traditionally used for feeding the silkworm in various countries. It belongs to the Urticales order, Moraceae family and genus Morus. The better known species, M. alba and M. nigra, seem to have originated in the Himalaya’s foothills (FAO, 1990). In Mulberry has excellent nutritional value as forage. Benavides (1991) reported CP values higher than 20 percent and IVOMD above 80 percent.
The literature gives the following climatic ranges for mulberry cultivation: temperature between 18 and 30°C; rainfall between 600 and 2 500 mm; photoperiod between 9 and 13 hours/day; and relative humidity between 65 and 80 percent (FAO, 1988). Currently its cultivation is reported from sea level to 4 000 m, and it is reproduced by seed, stakes and grafting (FAO, 1990).
In Spain, mulberry was recommended for planting in association with other crops such as maize, potatoes, vegetables, alfalfa and fruit-trees, controlling spacing and pruning to avoid light competition. Some authors recommend planting at 80 cm between plants and rows (González, 1951). In other publications, densities of 30 000 plants per ha for low pruning (below 70 cm); 7-12 000 plants for medium pruning (70-170 cm); and between 2 250 and 6 000 plants for high pruning (above 170 cm) are mentioned (FAO, 1988).
The available yield information is almost exclusively on leaves, since they are used to feed the silkworm. In France, fresh leaf yields of 17 000 kg/ha are reported with 7 x 7 m spacing. With higher densities, yields of 30 000 kg/ha have been obtained. Yields are related to plantation age and more specifically trunk diameter (Secretain and Gaddo, 1934, cited by González, 1951). These authors report that annual leaf production in monoculture increases from 6 500 kg to 33 500 kg/ha from the first to the seventh year. In good land, leaf yield per plant varies from 9 to 70 kg when average trunk diameter increases from 7 to 55 cm (Secretain, 1924, cited by González, 1951). With 22.5 tonnes of human faeces and 300 kg of ammonium sulphate, fresh leaf production can reach 13 tonnes/ha/year (FAO, 1988). In Paraguay, leaf yields of 20 000 kg/ha have been obtained in four year plantation harvesting at 30 cm from the surface (Narimatsu and Kiyoshi, 1975).
With widely spaced plants in Turrialba (Costa Rica) a yield of 2.32 kg of DM per plant was calculated per year, cutting at a height of 50 cm. Cutting at 1 m, the yield decreased to 2.16 kg. However, leaf production was 1 kg for both cutting heights. With cuts every 60, 120 and 180 days, total DM production was 1.64, 2.17 and 2.86 kg/plant/year, respectively. However, leaf production declined from 1.11 to 0.84 kg between 60 and 180 days (Benavides, Borel and Esnaola, 1986).
Nutritional value of mulberry
Dry matter content. The nutritive value of mulberry is one of the highest found in products of vegetable origin, far superior to traditional forages like alfalfa. Mulberry biomass is remarkable since the plant has characteristics that are is found in very few others: high levels of CP and high levels of digestible energy. Mulberry is also notable for its good mineral content and particularly for its low fibre content.
TABLE 1
Dry matter, crude protein and IVDMD of Mulberry foliage and other feeds used in Central America (Espinosa, 1996)
|
Item |
DM % |
CP % |
IVDMD % |
|
Mulberry (M. alba) |
28.7 |
23.0 |
80.0 |
|
King grass (P. purpureum x P. typhoides) |
20.0 |
8.2 |
52.7 |
|
Star grass (Cynodon lnemfluensis) |
22.3 |
8.9 |
54.9 |
|
Commercial concentrate |
91.5 |
17.7 |
85.0 |
Source: Espinosa, 1996.The content of dry matter (DM) and other components in the leaves of mulberry is higher when compared with traditional grasses used in animal feeding (Table 1). From Costa Rica there are reports of 25-32 percent DM in leaves; 23-29 percent in young stems; and 24-45 percent in woody stems (Benavides et al., 1996; Espinoza, 1996). In plantations of three Mulberry varieties 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 fertilization levels, it was found that DM content of leaves and edible stem was more affected by the location than by fertilization level, without differences among varieties (Table 2).
TABLE 2
Site and nitrogen fertilization effects on leaf DM content in three Mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety % DM |
Mean2
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
31.6 |
32.0 |
30.7 |
31.4b |
|
Coronado |
26.8 |
25.7 |
22.2 |
24.9c |
|
Paquera |
29.0 |
36.0 |
31.9 |
32.3a |
|
N1, kg/ha/year |
||||
|
180 |
29.2 |
31.4 |
28.8 |
29.8a |
|
360 |
28.9 |
31.5 |
28.6 |
29.7ab |
|
540 |
29.2 |
30.8 |
27.4 |
29.1b |
|
Mean2 |
29.1b |
31.2a |
28.3c |
|
1 ammonium nitrateIn woody stems, the differences were still more pronounced, with values between 27 and 48 percent of DM (Table 3). The small effect of fertilization on DM was also reported in a plantation where various levels of goat manure were applied (Table 4).
2 values with the same letter are not statistically different. P < 0.05.
Source: Espinosa, 1996.
TABLE 3
Site and nitrogen fertilization effects on woody stem DM content in three mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety, % DM |
Mean1
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
45.2 |
41.9 |
42.9 |
43.4b |
|
Coronado |
31.6 |
27.1 |
24.2 |
27.6c |
|
Paquera |
48.8 |
47.8 |
48.8 |
48.5a |
|
N, kg/ha/year |
||||
|
180 |
42.7 |
39.2 |
39.8 |
40.6a |
|
360 |
41.8 |
39.9 |
38.4 |
40.0a |
|
540 |
41.2 |
37.8 |
37.8 |
38.9b |
|
Mean1 |
41.9a |
38.9b |
38.6b |
|
1 = Values with the same letter are not statistically different. P <0.05.TABLE 4
DM content of mulberry (M. alba) by soil manure application
|
Fraction % MS
|
Manure level1 |
NH4NO31 |
|||
|
0 |
240 |
360 |
480 |
480 |
|
|
Leaves2 |
26.4a |
25.9bc |
26.0b |
25.5d |
25.6cb |
|
Young stem |
28.0a |
27.1b |
26.8b |
26.0c |
24.7d |
|
Woody stem |
42.2a |
41.5b |
40.8c |
40.4cd |
40.0d |
1 = kg de N/ha/year.Mulberry leaves have high levels of CP and IVOMD when compared with other ruminant feeds. Data from Central America indicate CP values between 15-25 percent and IVOMD between 75 and 90 percent, which indicate a quality with comparable or superior to commercial concentrates (Table 5). Non-lignified stems also have a good nutritional quality, with CP values of 7-14 percent and IVOMD of 56 and 70 percent (Benavides, Lachaux and Fuentes, 1994; Espinoza, 1996; Rojas, Benavides and Fuentes, 1994)
2 = Values with same letter horizontally are not statistically different. P <0.001.
Source: Benavides, Lachaux and Fuentes, 1994.
As was the case for DM, CP and IVDMD are similar among varieties and are not much affected by fertilization or by cutting frequency (Tables 6, 7, 8, 9, 10 and 11) although an effect was observed on the CP content of leaves and young stems when ammonium nitrate was added instead of goat manure at iso-nitrogenous levels (Table 9).
TABLE 5
Site and nitrogen fertilization effect on crude protein in three mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety, % PC |
Mean
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
20.1 |
22.2 |
21.0 |
21.1b |
|
Coronado |
22.2 |
26.3 |
25.7 |
24.8a |
|
Paquera |
17.0 |
14.8 |
13.7 |
15.1c |
|
N, kg/ha/year |
||||
|
180 |
18.9 |
20.8 |
20.0 |
19.9a |
|
360 |
20.5 |
20.8 |
19.9 |
20.4a |
|
540 |
20.0 |
21.6 |
20.6 |
20.7a |
|
Average |
19.8a |
21.1a |
20.1a |
|
Source: Espinoza, 1996.TABLE 6
Site and nitrogen fertilization effect on crude protein of young stem in three mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety, % CP |
Mean
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
11.2 |
13.0 |
12.1 |
12.1a |
|
Coronado |
13.4 |
13.9 |
14.3 |
13.9a |
|
Paquera |
9.4 |
10.2 |
8.7 |
9.4b |
|
N, kg/ha/year |
||||
|
180 |
11.2 |
12.7 |
11.6 |
11.4a |
|
360 |
11.8 |
11.8 |
11.8 |
11.7a |
|
540 |
11.3b |
12.6a |
11.7b |
11.9a |
|
Mean |
11.3b |
12.4a |
11.7b |
|
Source: Espinoza, 1996.TABLE 7
Site and nitrogen fertilization effect of leaf IVDMD in three Mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety, % IVDMD |
Mean
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
78.0 |
75.5 |
76.8 |
76.7a |
|
Coronado |
75.4 |
73.8 |
75.6 |
74.9a |
|
Paquera |
71.6 |
71.2 |
71.6 |
71.5b |
|
N, kg/ha/year |
||||
|
180 |
74.9 |
72.6 |
75.0 |
74.2a |
|
360 |
74.8 |
73.6 |
74.1 |
74.2a |
|
540 |
75.3 |
74.2 |
74.9 |
74.8a |
|
Year |
75.0a |
73.5a |
74.7a |
|
Source: Espinoza, 1996.TABLE 8
Site and nitrogen fertilization effect on IVDMD of young stems in three Mulberry (M. alba) varieties in Costa Rica
|
Site
|
Variety, % IVDMD |
Mean
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Puriscal |
69.5 |
70.5 |
63.9 |
68.0a |
|
Coronado |
70.3 |
68.6 |
69.9 |
69.6ª |
|
Paquera |
65.9 |
64.7 |
59.4 |
63.3b |
|
N, kg/ha/year |
||||
|
180 |
68.5 |
68.2 |
65.4 |
67.4ª |
|
360 |
68.9 |
69.0 |
64.2 |
67.4ª |
|
540 |
68.2 |
66.6 |
63.7 |
66.2ª |
|
Average |
68.6a |
67.9a |
64.4b |
|
Source: Espinoza, 1996.TABLE 9
Manure application effect on crude protein content of Mulberry leaf and young stem
|
Fraction
|
Manure level1 |
NH4NO31 |
|||
|
0 |
240 |
360 |
480 |
480 |
|
|
Leaves2 |
19.1c |
19.3b |
19.3c |
20.2b |
22.5ª |
|
Young stem |
7.4b |
7.1b |
7.2b |
7.4b |
12.3ª |
1 Equivalence in kg of N/ha/year.TABLE 10
2 Values with the same letter horizontally are not statistically different. P <0.01.
Source: Benavides, Lachaux and Fuentes, 1994.
Manure application effect on DM digestibility of Mulberry leaf and young stem
|
Fraction
|
Manure level1 |
NH4NO31 |
|||
|
0 |
240 |
360 |
480 |
480 |
|
|
Leaves |
76.7 |
77.5 |
77.0 |
76.9 |
77.1 |
|
Young stem2 |
56.2b |
56.4b |
56.0b |
55.8b |
58.6ª |
1 = Equivalence in kg of N/ha/year.TABLE 11
2 = Values with the same letter horizontally are not statistically different. P <0.01.
Source: Benavides, Lachaux and Fuentes, 1994.
Annual cutting frequency effect on digestibility and crude protein content of Mulberry biomass
|
Fraction
|
percent CP |
percent IVDMD |
||
|
3 |
4 |
3 |
4 |
|
|
Leaves1 |
19.2b |
20.9a |
77.2 |
76.9 |
|
Young stem |
8.1 |
8.5 |
56.9 |
56.2 |
1 values with the same letter horizontally are not statistically different. P <0.01.In the studies mentioned above, a marked site effect is reported, which is the result of the different soil and climatic conditions of each one. In Paquera, located in the Pacific Coast of Costa Rica, with high luminosity and high temperatures, leaf CP and IVDMD (15.1 and 71.5 percent, respectively) are reduced compared to higher locations with more clouds and lower temperatures ((24.8 and 74.9 percent, respectively), like is the case of Coronado and Puriscal, located in the mountainous areas of the country (Espinoza, 1996). The greater luminosity and higher temperature in Paquera can explain the lower water content in all fractions, lower CP and IVDMD levels, and high DM production, as will be seen later. It is known that high luminosity reduces nitrate levels and increases cell wall components and growth because of larger photosynthetic activity (Van Soest, 1994). Coronado has lower temperatures and more cloudiness and rainfall, which could mean limited growth and lignification. But high soil fertility and lower growth rates of this site explain the higher CP and lower biomass DM. In addition to the climatic factors of Paquera, the lower N, copper and zinc soil contents could limit fertility and nutrient content in the plant. On the other hand, the clay soils, lower pH and low potassium contents can explain the low biomass yields in Puriscal.
Source: Benavides, Lachaux and Fuentes, 1994.
Goats fed exclusively on mulberry and Amapola leaves confined to metabolic cages, apart from high DM intake values showed, high levels of in vivo DM and CP digestibilities of mulberry leaves (Table 12). The values reached 90 percent for leaf CP digestibility (Jegou, Waelput and Brunschwig, 1994).
TABLE 12
DM and crude protein in vivo digestibilities of mulberry and Amapola (Malvaviscus arboreus) with goats in metabolic cages
|
Forage species
|
Parameters |
||
|
Intake, % LW |
IVDMD, % |
IVCPD, % |
|
|
Mulberry |
4.18 |
79.3 |
89.5 |
|
Amapola |
4.35 |
64.2 |
54.2 |
Source: Jegon, Waelput and Brunschwig, 1994.Although statistical comparisons have not been made, nitrogen, potassium and calcium contents of leaves and young stems are high (Tables 13 and 14), reaching values of 3.35, 2.0 and 2.5 percent, respectively (Espinoza, 1996). In other trials (Table 15), no appreciable differences were found in the mineral content of leaves and young stems when increasing amounts of legume leaves were added to the soil (Oviedo, 1995).
In a report on the proximate analysis of Kanvas-2 variety of mulberry (Table 16), levels of protein (29.6 percent), ash (7.53 percent) and nitrogen-free extract (50.0 percent) were considered high. At the same time, low levels of crude fibre were reported (10.1 percent). In these trials, the type and quantity of leaf amino acids were determined. Twenty-four amino acids in significant concentrations were detected, plus six more at low concentrations (Table 17). The low fibre level and high contents of CP and IVDMD justify future evaluations of mulberry as an ingredient for high quality meal and compound feeds.
TABLE 13
Fertilization effect on the mineral content of mulberry (M. alba) leaf in Costa Rica
|
Variety
|
Minerals, % of DM |
||||
|
N |
P |
K |
Ca |
Mg |
|
|
Criolla |
3.17 |
0.30 |
2.07 |
1.90 |
0.47 |
|
Indonesia |
3.37 |
0.30 |
1.73 |
2.87 |
0.63 |
|
Tigriada |
3.23 |
0.40 |
2.33 |
2.74 |
0.55 |
|
N, kg/ha/year |
|||||
|
180 |
3.18 |
0.33 |
1.96 |
2.54 |
0.55 |
|
360 |
3.26 |
0.33 |
2.05 |
2.49 |
0.55 |
|
540 |
3.32 |
0.33 |
2.12 |
2.48 |
0.55 |
|
Mean |
3.26 |
0.33 |
2.04 |
2.50 |
0.55 |
Source: Espinoza, 1996.TABLE 14
Fertilization effect on mineral content of mulberry (M. alba) young stems in Costa Rica
|
Variety
|
Minerals, % of DM |
||||
|
N |
P |
K |
Ca |
Mg |
|
|
Criolla |
1.81 |
0.30 |
2.24 |
1.33 |
0.39 |
|
Indonesia |
1.98 |
0.40 |
2.99 |
1.53 |
0.49 |
|
Tigriada |
1.87 |
0.33 |
2.41 |
1.38 |
0.40 |
|
N, kg/ha/year |
|||||
|
180 |
1.89 |
0.33 |
2.48 |
1.43 |
0.44 |
|
360 |
1.86 |
0.33 |
2.60 |
1.40 |
0.43 |
|
540 |
1.90 |
0.37 |
2.55 |
1.42 |
0.41 |
|
Mean |
1.89 |
0.34 |
2.55 |
1.41 |
0.43 |
Source: Espinoza, 1996.TABLE 15
Mulberry leaf mineral content as affected by level of Poro foliage added to the soil
|
Mineral
|
Control Without trees
|
Proportion of Poro foliage in the soil |
Mean
|
||
|
0% |
50% |
100% |
|||
|
N |
2.90 |
3.16 |
3.10 |
3.09 |
3.06 |
|
P |
0.22 |
0.22 |
0.22 |
0.23 |
0.22 |
|
K |
1.51 |
1.37 |
1.35 |
1.71 |
1.49 |
|
Ca |
1.64 |
1.82 |
1.74 |
1.77 |
1.74 |
|
Mg |
0.42 |
0.44 |
0.41 |
0.38 |
0.41 |
Source: Oviedo, 1995TABLE 16
Leaf composition of mulberry variety Kanvas-1, in El Salvador, Central America
|
Leaf position
|
Fractions, % of DM |
|||||
|
Dry matter |
Crude protein |
Crude fat |
Crude fibre |
Ash |
NFE |
|
|
Terminal |
19.5 |
33.6 |
3.2 |
9.4 |
7.7 |
46.1 |
|
Intermediate |
22.5 |
28.3 |
2.8 |
10.2 |
7.3 |
51.4 |
|
Basal |
23.0 |
26.7 |
3.4 |
10.8 |
7.7 |
52.6 |
|
Average |
21.7 |
29.6 |
3.1 |
10.1 |
7.5 |
50.0 |
Source: Coto, 1996.TABLE 17
Amino acid concentration in the leaves of Mulberry variety Kanva-1 in El Salvador, Central America
|
Amino acid |
g/100 g of DM |
Amino acid |
g/100 g of DM |
Amino acid |
mg/100 g of DM |
|
Alanine |
1.2 |
Methionine |
0.4 |
Glutathione |
350 mg |
|
Arginine |
1.1 |
Phenyl-alanine |
1.1 |
5Hydroxypipecolic acid |
36 mg |
|
Aspartic acid |
2.1 |
Proline |
1.1 |
Pipecolic acid |
10 mg |
|
Cisteine |
0.6 |
Serine |
1.2 |
Sarcosine |
0.5 mg |
|
Glutamic acid |
2.7 |
Threonine |
0.9 |
Adenylic acid |
Trace |
|
Glycine |
1.5 |
Tryptophan |
0.3 |
Cytidylic acid |
Trace |
|
Histidine |
0.6 |
Tyrosine |
0.6 |
Guanylic acid |
Trace |
|
Isoleucine |
1.4 |
Valine |
1.4 |
Hydroxanthine |
Trace |
|
Leucine |
1.8 |
Amino-benzoic acid |
8 mg |
Trigoneline |
Trace |
|
Lysine |
1.8 |
Choline |
112 mg |
Uridylic acid |
Trace |
Source: Coto, 1996.Animal Response
Evaluations carried out with ruminants (cattle, goats and sheep) show high intake levels of DM and high animal responses in weight gain and milk yield. Oviedo (1995), when comparing mulberry foliage with concentrate (Table 18) as supplements to Jersey x Criollo grazing cows, found similar milk yields with both supplements (13.2 and 13.6 kg/animal/day, respectively) at equal DM intake levels (1.0 percent of LW) and superior to grazing only (11.3 kg/animal/day). Mulberry inclusion did not affect fat, protein and total solids content in milk (Table 19), but improved net benefits when compared with the concentrate (US$ 3.29 against 2.84, respectively).
TABLE 18
Milk yield and DM intake of Jersey x Criollo cows grazing Star grass (Cynodon nlemfuensis) and supplemented with mulberry or concentrate
|
Feed consumed, % LW |
Supplement concentrate |
Mulberry |
Nothing |
|
Milk, kg/animal/day |
12.45 |
12.08 |
10.34 |
|
Concentrate |
1.0 |
|
|
|
Mulberry |
|
1.0 |
|
|
Star grass |
3.7 |
3.4 |
3.7 |
|
Total |
4.7 |
4.4 |
3.7 |
Source: Oviedo, 1995.TABLE 19
Milk chemical composition from grazing cows supplemented with Mulberry or concentrates
|
Component |
Supplement concentrate |
Mulberry |
Nothing |
|
Fat |
3.95 |
3.81 |
3.63 |
|
Protein |
3.53 |
3.51 |
3.31 |
|
Total solids |
12.53 |
12.39 |
12.31 |
Source: Oviedo, 1995.Esquivel et al. (1996), when replacing 0, 40 and 75 percent of the concentrate by mulberry foliage, did not find significant differences (P <0.05) in milk production (14.2; 13.2 and 13.8 kg/animal/day, respectively) in Holstein cows grazing Kikuyo grass (Pennisetum clandestinum) nor appreciable effects on milk quality (Table 20). Also in these trials, considering only feeding costs, net income per animal was 11.5 percent higher with the maximum level of mulberry than that obtained with concentrate only.
TABLE 20
Effect of the substitution of concentrate by mulberry foliage on the milk yield of Holstein cows grazing Kikuyo grass (Pennisetum clandestinum)
|
Parameter
|
Relation concentrate: mulberry |
||
|
100/0 |
60/40 |
25/75 |
|
|
Milk, kg/animal/day |
14.2 |
13.2 |
13.8 |
|
Intake, kg DM/animal/day |
|||
|
Concentrate |
6.4 |
4.2 |
1.9 |
|
Mulberry |
0 |
2.8 |
5.5 |
|
Grass |
9.3 |
7.8 |
6.2 |
|
Total |
15.7 |
14.8 |
13.6 |
Source: Esquivel et al., 1996.With cattle, attractive liveweight gains have been obtained when using mulberry foliage as a supplement. In the humid tropics of Turrialba (Costa Rica), Jersey x Criollo heifers grazing Star grass (Cynodon nlemfuensis) and supplemented with concentrate, mulberry and concentrate or only mulberry, no statistical differences were detected (P <0.05) among supplements (Table 21). The combination mulberry and concentrate gave the highest gains (742 g/animal/day) (Oviedo and Benavides, 1994).
TABLE 21
Intakes and liveweight gains of grazing dairy heifers supplemented with concentrate and mulberry foliage
|
Parameter |
Only concentrate |
Concentrate + mulberry |
Mulberry |
|
Liveweight gain |
0.620 |
0.742 |
0.600 |
|
Intake of mulberry, % LW |
- |
0.5 |
1.0 |
|
Intake of concentrate, % LW |
1.0 |
0.5 |
- |
Source: Oviedo, 1995.With young Romosinuano bulls in total confinement and fed a basal diet of Elephant grass (Pennisetum purpureum), gains of 40, 690, 940 and 950 g/animal/day were observed with whole mulberry DM intakes of 0, 0.90, 1.71 and 2.11 percent of LW as supplement (González et al, 1996). In this study, the benefit/cost relations were 0.10, 1.11, 1.18 and 0.97 for each of the gain levels, respectively. The study lasted 70 days and animals were between 13 and 16 months old, with initial liveweight between 118 and 250 kg (Table 22).
TABLE 22
Effect of mulberry supplementation on intake and liveweight gains of Romo-sinuano cattle in confinement and fed a basal diet of Elephant grass
|
DM intake, % LW1
|
Mulberry DM offered, % LW |
|||
|
0 |
1.0 |
1.9 |
2.8 |
|
|
Fresh Mulberry |
0.00d |
0.90c |
1.71b |
2.11a |
|
Elephant grass |
2.04a |
1.79a |
1.29b |
0.95b |
|
Total diet |
2.04c |
2.69b |
3.00a |
3.06a |
|
Weight gain, g/animal/day |
0.04c |
0,69b |
0,94a |
0,95a |
1 Values with the same letter horizontally are not statistically different (P <0.05) with the Tukey test.With crossbred dairy goats of 40 kg liveweight, Rojas, Benavides and Fuentes (1994) found milk yield increases of 2.0 and 2.5 kg/animal/day when mulberry supplementation was raised from 1.0 to 2.6 percent of LW on a DM basis (Table 23). There were slight increases in the fat, protein and total solids content (Table 24). In this study, high DM intakes and the additive effect of mulberry supplementation were observed. King grass was clearly substituted by mulberry (Table 25).
Source: González et al., 1996.
TABLE 23
Effect of mulberry supplementation on milk yield (kg/animal/day) of dairy goats
|
Production level
|
Level of Mulberry DM, % LW |
Mean1
|
|||
|
1.0 |
1.8 |
2.6 |
3.4 |
||
|
High |
2.04 |
2.38 |
2.51 |
2.47 |
2.35 |
|
Low |
1.64 |
1.82 |
1.91 |
2.12 |
1.87 |
|
Mean2 |
1.84b |
2.10b |
2.21ab |
2.29ª |
|
1 group averages differ statistically, P <0.0001.TABLE 24
2 values with same letter horizontally are not statistically different, P <0.0001.
Source: Rojas and Benavides, 1994.
Effect of mulberry supplementation on fat, protein and total solid contents of goats fed King grass
|
Fraction
|
Intake of mulberry DM, % LW |
Mean1 |
|||
|
1.0 |
1.8 |
2.6 |
3.4 |
||
|
Fat |
3.1 |
3.2 |
3.2 |
3.3 |
3.2 |
|
Protein |
3.3 |
3.4 |
3.4 |
3.5 |
3.4 |
|
Total solids |
10.7b |
11.0b |
11.4a |
11.2ab |
11.1 |
TABLE 25
Effect of mulberry supplementation on DM intake of confined dairy goats
|
Forage |
DM intake, % LW |
|||
|
Mulberry |
1.0 |
1.8 |
2.6 |
3.4 |
|
King grass |
3,2a |
2.9ab |
2.6b |
2.1c |
|
Total |
4.2c |
4.7b |
5.2ab |
5.5a |
1 group means differ statistically, P <0.0003.With Black Belly lambs receiving a basal diet of King grass, liveweight gains of 60, 75, 85 and 101 g/animal/day were reported when mulberry was given as a supplement at 0, 0.5, 1.0 and 1.5 percent of LW on a DM basis, respectively (Benavides, 1986). In this study, rather than a substitution effect, there was an additive effect of mulberry on total DM intake (Table 26).
2 values with the same letter horizontally are not statistically different, P <0.0006.
Source: Rojas, Benavides and Fuentes 1994.
TABLE 26
Performance of Black Belly lambs fed various mulberry levels
|
Parameters
|
Mulberry level, DM as % of LW |
Significance
|
|||
|
0 |
0.5 |
1.0 |
1.5 |
||
|
Initial weight, kg |
15.7 |
15.8 |
15.8 |
15.1 |
|
|
Final weight, kg |
21.5 |
22.6 |
24.4 |
25.6 |
|
|
Gain, g/day |
60c |
75b |
85b |
101ª |
** |
|
DM intake (kg/day) |
|
|
|
|
|
|
King grass |
0.66 |
0.60 |
0.62 |
0.60 |
|
|
Mulberry leaf |
0 |
0.09 |
0.19 |
0.28 |
|
|
Total DM intake |
0.66 |
0.69 |
0.81 |
0.88 |
** |
|
DM intake, percent LW |
3.54 |
3.72 |
3.99 |
4.34 |
** |
|
DM intake, g/kg/PV0.75 |
73.5 |
75.1 |
84.5 |
92.2 |
** |
Source: Benavides, 1996.In a three-year evaluation (Table 27), in an agroforestry model with goats fed exclusively (at 3 percent LW on a DM basis) with King grass and mulberry, a lactation yield of 900 kg per 300 days was reported (Oviedo, Benavides and Vallejo, 1994). This is equivalent to a mean of 3 kg/day and to 4.1 kg/day at the beginning of lactation. Forage came from a mulberry and grass plantation associated with Poro (Erythrina poeppigina) measuring 1 100 m2, fertilized with goat manure, Poro foliage and feed rejects.
TABLE 27
Milk yield (kg/animal/day) in dairy goats fed exclusively grass and Mulberry foliage in the agroforestry model
|
Month |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
|
Goat 1 |
3.22 |
3.46 |
3.47 |
3.41 |
2.65 |
2.69 |
2.23 |
2.44 |
2.53 |
|
Goat 2 |
3.41 |
3.93 |
3.53 |
3.44 |
2.91 |
2.67 |
2.68 |
1.86 |
1.71 |
Source: Oviedo, Benavides and Vallejo, 1994.During the third year, the module reached 5.0 kg/day, equivalent to 16 500 kg/ha/year (Table 28). The economic analysis indicated a benefit/cost relation of 1.27, 1.39 and 1.45 for each year, respectively (Table 29).
Ensiled mulberry
One of the most serious problems of livestock husbandry in the tropics is the rapid decline of grass quality during the dry season. Among the most used alternatives is forage conserved by ensiling during the rainy season in order to be used in the dry season. However, silage is traditionally made with tropical grasses rich in fibre and low in soluble carbohydrates, which affects fermentation and results in a low quality product. Because of its low fibre and high level of carbohydrates, mulberry foliage can be ensiled without additives, showing a lactic fermentation pattern and low CP losses (between 16-21 percent of CP in the final product) while maintaining between 66 and 71 percent IVDMD (Vallejo, 1995; González et al., 1996). These parameters are far superior to silages made with tropical forages. Vallejo (1994), using 40 kg plastic bags and three 30-day storage periods, compared the silage made from three tree foliages (mulberry, Amapola and Jocote). Mulberry showed the highest levels of IVDMD, good CP content, acceptable losses of ammonium nitrogen and higher lactic acid levels (Table 30). Acetic and butyric acids levels were also high with mulberry in the first period, but rapidly declined (Table 31).
TABLE 28
Zootechnical parameters of confined goats in the agroforestry model in Turrialba, Costa Rica
|
Parameter |
Average |
Year1 |
Year2 |
Year3 |
|
Lactation, months |
14.61 |
|
|
|
|
Kids per parturition |
2.0 |
|
|
|
|
Kid weight at birth, kg |
3.7 |
|
|
|
|
Milk, kg/animal/day |
2.02 |
|
|
|
|
Dry period, days |
37.3 |
|
|
|
|
Goat weight, kg |
50.0 |
|
|
|
|
Total milk, kg/year |
|
1223.03 |
1505.94 |
1110.55 |
|
Milk production, kg per module/day |
4.0 |
3.4 |
4.2 |
5.0 |
|
Maximum monthly |
|
42.8 |
71.4 |
122.7 |
|
Minimum monthly |
|
145.1 |
189.1 |
207.9 |
|
Minimum per module/day |
|
1.4 |
2.3 |
4.0 |
|
Maximum per module/day |
|
5.2 |
6.1 |
6.7 |
1 Three lactations per goat. 2 Data of 31.5 months. 3 From 03/91 to 03/92. 4 From 03/92 to 03/93. 5 From 03/93 to 10/93.González et al. (1996) found better fermentation indicators in two nine-tonne mulberry silage pits for feeding young bulls, than Vallejo (1994). They noted high levels of lactic acid and low concentrations of propionic and butyric acids (Table 32). The pH remained close to the values reported previously by Vallejo (1994) and, when opening the silo, the organoleptic characteristics were excellent: a green colour and lactic smell. Nevertheless, once in the feeder the silage lost its characteristic colour and smell within two hours.
Source: Oviedo, Benavides and Vallejo, 1994.
TABLE 29
Financial analysis (in US$) of the goat agroforestry module at Turrialba, Costa Rica
|
Description
|
Years |
||
|
1991/92 |
1992/93 |
1993* |
|
|
A. Costs |
|
|
|
|
A.1 Investments |
|
|
|
|
Mulberry x Poró plantation |
4.61 |
4.61 |
2.88 |
|
Grass x Poró plantation |
1.66 |
1.66 |
1.04 |
|
Facilities |
16.07 |
16.07 |
9.37 |
|
Animals |
50.00 |
50.00 |
31.25 |
|
Subtotal |
72.34 |
72.34 |
45.21 |
|
A.2 Fixed, land opportunity cost |
21.17 |
21.17 |
13.23 |
|
A.3 Variables (labour) |
|
|
|
|
Cut & carry, weeding, pruning |
182.65 |
176.19 |
109.77 |
|
Forage chopping and feeding |
138.45 |
133.55 |
83.20 |
|
Milking |
89.05 |
85.90 |
53.52 |
|
Cleaning facilities |
54.60 |
52.67 |
32.81 |
|
Manure application |
26.00 |
25.08 |
15.63 |
|
Mineral salts |
30.66 |
30.66 |
19.16 |
|
Antelmintic |
1.40 |
1.40 |
1.40 |
|
Maintenance |
6.50 |
6.27 |
3.90 |
|
Subtotal |
455.31 |
511.72 |
319.39 |
|
Total cost |
527.65 |
584.06 |
377.83 |
|
Updated cost |
610.82 |
643.92 |
396.72 |
|
B. Income |
|
|
|
|
B.1 Milk production |
672.66 |
813.99 |
549.03 |
|
Updated income |
778.68 |
897.42 |
576.48 |
|
C. B - A updated |
167.86 |
253.50 |
179.76 |
|
B/C |
1.27 |
1.39 |
1.45 |
* 7.5 months of 1993.TABLE 30
Source: Oviedo, Benavides and Vallejo, 1994.
Chemical characterisation of silage made from shrubs and trees
|
Species |
% DM |
% IVDMD |
% CP |
||||||
|
Period |
1 |
2 |
3 |
1 |
2 |
3 |
1 |
2 |
3 |
|
Mulberry |
22.1 |
28.7 |
34.3 |
60.5 |
61.6 |
76.9 |
17.9 |
17.0 |
16.7 |
|
Amapola |
28.9 |
30.9 |
35.7 |
51.1 |
55.5 |
68.5 |
16.3 |
16.0 |
16.9 |
|
Jocote |
20.6 |
22.0 |
19.8 |
49.3 |
58.0 |
74.2 |
17.0 |
17.5 |
15.9 |
TABLE 31
Fermentation indicators of ensiled foliage of three woody forages
|
Variable
|
Period
|
Species |
||
|
Mulberry |
Amapola |
Jocote |
||
|
pH
|
1 |
5.4 |
5.0 |
2.9 |
|
2 |
4.6 |
5.0 |
3.1 |
|
|
3 |
5.1 |
5.0 |
2.8 |
|
|
percent Total NH3-nitrogen
|
1 |
2.27 |
0.96 |
1.00 |
|
2 |
1.56 |
0.81 |
1.28 |
|
|
3 |
1.26 |
0.16 |
0.91 |
|
|
percent Acetic acid
|
1 |
5.71 |
1.49 |
1.11 |
|
2 |
1.97 |
1.25 |
1.57 |
|
|
3 |
0.85 |
0.16 |
1.10 |
|
|
percent Butyric acid
|
1 |
6.84 |
0.24 |
0.03 |
|
2 |
0.56 |
0.24 |
0.01 |
|
|
3 |
0.32 |
0.02 |
0.00 |
|
|
percent Lactic acid
|
1 |
5.14 |
4.64 |
0.71 |
|
2 |
9.00 |
4.26 |
1.84 |
|
|
3 |
6.22 |
1.38 |
0.63 |
|
Fermentation indicators of Mulberry silage used as supplement for Romo-sinuano cattle
|
Indicator |
Silo 1 |
Silo 2 |
Average |
|
pH |
4.45 |
5.25 |
4.85 |
|
NH3, percent of total N |
7.70 |
4.16 |
5.93 |
|
Acetic acid, percent |
3.95 |
1.82 |
2.89 |
|
Propionic acid, percent |
0.27 |
0.08 |
0.18 |
|
Butyric acid, percent |
0.02 |
0.03 |
0.03 |
|
Lactic acid, percent |
12.93 |
17.15 |
15.04 |
Source: González et al., 1996.Using this mulberry silage to supplement young bulls fed a basal diet of Elephant grass, liveweight gains of 600 g/day were obtained (Table 33) with silage intake of 1.1 percent of LW on DM basis (González et al., 1996). However, although mulberry silage intake was similar to that observed with other grass silages (Esperance and Guerra, 1978), there was a lot of refusal. The low intake was not expected due to CP and IVDMD contents. The explanation could be in the physical and chemical aspects of the silage, such as its high pH and compaction, which might have reduced consumption. This forage without an additive does not reach the desirable pH levels to assure stability. González (1996) observed this in a study with micro-silos, where after 60 days the pH never dropped below 4.5.
The conclusions that can be reached from the use of silage of woody forages relate to the species used. This observation also comes from a study with dairy goats fed silage made from three woody forages (Table 34), where a very high mulberry silage intake (near 5 percent of LW on DM basis) was found and there was a milk yield of 1.9 kg/day (Vallejo, 1994).
TABLE 33
Effect of mulberry silage supplementation on intake and weight gain of Romo-sinuano cattle fed a basal diet of Elephant grass
|
DM intake
|
Mulberry dry matter offered, % LW |
|||
|
0 |
0.8 |
1.7 |
2.5 |
|
|
Ensiled mulberry, % LW1 |
0c |
0.66b |
1.05a |
1.11ª |
|
Total DM, % LW |
2.16b |
2.42a |
2.61a |
2.64ª |
|
Weight gain, g/animal/day |
117b |
404a |
490a |
601ª |
1 Values with the same letter horizontally are not statistically different, (P <0.05), using the Tukey test.TABLE 34
Source: Vallejo, 1994
Intake, milk yield and characteristics of goats fed silage of three woody forages as sole diet
|
Species
|
DM intake, % LW |
Milk, kg/day1 |
Milk chemical composition |
|||
|
Protein% |
Fat % |
Total solids % |
Titratable acidity |
|||
|
Mulberry |
4.90a |
1.88a |
3.2a |
3.4a |
11.8a |
0.16a |
|
Amapola |
4.35ab |
1.83a |
3.1a |
3.2a |
11.1a |
0.16a |
|
Jocote |
3.23b |
1.29b |
3.4a |
2.8a |
12.0a |
0.17a |
1 = Values with same letter horizontally are not statistically different (P<0.05)AGRONOMY
Mulberry has high biomass production, as shown in several experiments where the effects on yield and quality of cutting frequency, level and type of fertilization and location have been studied. Because of its high production capacity, mulberry extracts a lot of nutrients from the soil. This is why, a combination of organic and inorganic fertilizers has been emphasized.
One of the obvious worries about the agronomy of mulberry is the related stake planting. For this purpose an experiment was conducted to compare three woody forages and different planting methods (Table 35). In all cases mulberry showed a high germination percentage, superior to other forages. Placing stakes in the vertical position was better than horizontally.
TABLE 35
Effect on planting method on germination and number of shoots per stake of Mulberry, Amapola and Sauco
|
Species
|
Horizontal stake |
Vertical stake |
||||
|
% germ. |
Number of shoots |
Length of shoots (cm) |
% germ. |
Number of shoots |
Length of shoots (cm) |
|
|
Amapola |
58.0b |
1.0b |
7.2b |
87.5b |
4.3ª |
7.5b |
|
Mulberry |
90.4ª |
2.1ª |
15.9a |
100.0a |
3.1b |
22.5ª |
|
Sauco |
53.8b |
1.1b |
4.4b |
60.4c |
1.5c |
6.8b |
Source: Esquivel, 1993In an evaluation of cutting height (0.5 and 1.0 m) of isolated two year-old plants (Table 36), differences in DM and CP production were not found, although there was a significant effect on the proportion of leaf (Benavides, Borel and Esnaola, 1986). In this same study (Table 37), greater yields were observed with longer cutting frequencies (60, 120 and 180 days). However, this increase was due to more stem production, with leaf production not being affected.
TABLE 36
Dry matter yields (kg/plant/year) of mulberry at two cutting heights
|
Plant fraction
|
Cutting height |
P <
|
|
|
0.5 m |
1.0 m |
||
|
Total |
2.32 |
2.16 |
NS |
|
Leaf |
1.00 |
1.02 |
NS |
|
Stem |
1.32 |
1.14 |
NS |
|
Leaf fraction |
0.21 |
0.21 |
NS |
|
Leaf:stem |
1.04 |
1.29 |
** |
Source: Benavides, Borel and Esnaola, 1986.TABLE 37
Dry matter yields (kg/plant) of mulberry under different cutting frequencies
|
Fraction
|
Cutting frequency, days |
P <
|
||
|
60 |
120 |
180 |
||
|
Total |
1.64c |
2.17b |
2.86ª |
** |
|
Leaf |
1.11ª |
1.04ª |
0.84b |
** |
|
Stem |
0.52c |
1.08b |
2.01ª |
** |
|
Leaf fraction |
0.26ª |
0.23ª |
0.15b |
** |
|
Leaf:stem |
2.11ª |
1.06b |
0.45c |
** |
Source: Benavides, Borel and Esnaola, 1986.Under humid tropical conditions in Costa Rica, a mulberry plantation with 25 000 plants/ha produced 35 tonnes DM/year for three years using goat manure as fertiliser (Benavides, Lachaux and Fuentes, 1994). A 20% higher production with goat manure was observed than with ammonium nitrate, at equal levels of nitrogen application (Table 38). Significant increments in production were observed with greater manure applications. Overall yields increased 10 percent a year, reaching 38 tonnes of DM/ha by the third year. Greater total biomass yields were obtained (Table 39) with a four month cutting frequency compared with three months, although leaf yield was not different (Benavides, Lachaux and Fuentes, 1994).
TABLE 38
Yearly total mulberry biomass (tonnes of DM/ha) when applying goat manure as fertilizer and cutting every four months
|
Year
|
Level of manure1 |
NH4-NO3 |
|||
|
0 |
240 |
360 |
480 |
480 |
|
|
12 |
23.0c |
24.4bc |
26.6b |
31.1a |
26.7b |
|
2 |
21.3c |
25.2b |
27.6ab |
33.4a |
29.7b |
|
3 |
22.9d |
28.2c |
32.6b |
38.2a |
29.2b |
1 kg of N/ha/year.TABLE 39
2 Values with the same letter horizontally are not statistically different, P <0.001.
Dry Matter yields of mulberry (tonnes/ha/year) and cutting frequency
|
Fraction
|
Year |
Cuttings/year |
|||
|
1 |
2 |
3 |
3 |
4 |
|
|
Leaves1 |
10.8ab |
10.9a |
10.4b |
11.0 |
10.4 |
|
Young stem |
1.6a |
0.9b |
0.8c |
1.0b |
1.3ª |
|
Woody stem |
11.8c |
13.2b |
14.4ª |
16.0a |
10.3b |
|
Total |
24.2b |
25.0ab |
25.6a |
28.0a |
21.9b |
|
Edible |
12.4a |
11.8b |
11.2c |
12.0 |
11.6 |
1 Values with same letter horizontally are not statistically different, P <0.001.In another study, again under humid tropical conditions, Oviedo (1995) found mulberry biomass yields of 8.0, 9.4 and 10.6 tonnes of DM/ha when using Poró foliage as mulch equivalent to 0, 160 and 300 kg of N/ha/year, respectively.
Source: Benavides, Lachaux and Fuentes, 1994.
Working with three mulberry varieties (Criolla, Indonesia and Tigriada) in three sites of Costa Rica (Puriscal, Coronado and Paquera), Espinoza and Benavides (1996) reported important differences among varieties in total DM yields, having one variety with almost half the yields of the other two. Nitrogen application also affected yields according to site (Table 40). In Paquera, despite the long dry period and less fertile soils, average yields for all three varieties were almost double those of Coronado, where it rains all year. Edible biomass yield differences were smaller (Table 41). In Paquera lower leaf:stem proportion was observed (Tables 42 and 43) at similar cutting frequencies. This indicates that more frequent cuts can be given under conditions in that area.
TABLE 40
Site and nitrogen fertilizer effect on DM production of three Mulberry varieties in Costa Rica
|
Parameter
|
Variety, tonnes DM/ha/year |
Average
|
||
|
Criolla |
Tigriada |
Indonesia |
||
|
Site: |
||||
|
Puriscal1 |
11.1 |
15.6 |
19.0 |
15.2b |
|
Coronado |
8.9 |
19.5 |
18.0 |
15.5b |
|
Paquera |
22.4 |
31.9 |
39.2 |
31.2a |
|
Fertilization2 |
||||
|
180 kg N/ha |
11.2 |
18.0 |
19.2 |
16.1b |
|
360 kg N/ha |
13.7 |
22.8 |
28.3 |
21.6a |
|
540 kg N/ha |
17.4 |
26.3 |
28.7 |
24.1a |
|
Average |
14.1c |
22.3b |
25.4a |
|
1 Values with the same letter horizontally are not statistically different (P <0.05) with the Duncan test.TABLE 41
2 Ammonium nitrate. Maximum production: 45.2 tonnes/ha/year (Indonesia at Paquera with 360 kg N/ha/year). Minimum production: 6.5 tonnes/ha/year (Criolla at Puriscal with 180 kg N/ha/year).
Source: Espinoza, 1996.
Site and nitrogen fertilizer effect on edible DM percentage of three Mulberry varieties in Costa Rica
|
Parameter
|
Variety |
Average1
|
||
|
Criolla |
Tigriada |
Indonesia |
||
|
Site |
||||
|
Puriscal |
53.8 |
50.8 |
38.6 |
47.7b |
|
Coronado |
64.7 |
56.4 |
48.5 |
56.5a |
|
Paquera |
40.0 |
42.0 |
32.0 |
38.0c |
|
N, kg/ha/year |
||||
|
180 |
52.8 |
51.5 |
41.3 |
48.5a |
|
360 |
52.8 |
49.1 |
38.6 |
46.8a |
|
540 |
52.9 |
48.7 |
39.6 |
47.1a |
|
Average1 |
52.8a |
49.7b |
39.7c |
|
1 Values with the same letter horizontally are not statistically different, P <0.05 (Duncan, 1955).TABLE 42
Source: Espinoza, 1996.
Site and nitrogen fertilizer effect on leaf:stem relation in three Mulberry varieties in Costa Rica
|
Parameter
|
Variety |
Average1
|
||
|
Criolla |
Indonesia |
Tigriada |
||
|
Site |
||||
|
Puriscal |
1.00 |
0.56 |
0.89 |
0.82b |
|
Coronado |
1.40 |
0.71 |
0.87 |
0.99a |
|
Paquera |
0.61 |
0.44 |
0.67 |
0.57c |
|
N, kg/ha/year |
||||
|
180 |
1.03 |
0.60 |
0.87 |
0.83a |
|
360 |
0.99 |
0.54 |
0.81 |
0.78b |
|
540 |
1.00 |
0.57 |
0.75 |
0.77b |
|
Average1 |
1.00a |
0.57c |
0.81b |
|
1 Values with the same letter horizontally are not statistically different, P <0.05 (Duncan, 1955).TABLE 43
Source: Espinoza, 1996.
Site and nitrogen fertilizer effect on growth rates (tonnes DM/ha/year) of three Mulberry varieties in Costa Rica
|
Parameters
|
Variety |
Average
|
||
|
Criolla |
Tigriada |
Indonesia |
||
|
Site |
||||
|
Puriscal1 |
92.5 |
130.0 |
158.3 |
126.9b |
|
Coronado |
74.2 |
162.5 |
150.0 |
128.9b |
|
Paquera |
186.7 |
265.8 |
326.7 |
259.7a |
|
Fertilization2 |
||||
|
180 kg N/ha |
93.3 |
150.0 |
160.0 |
134.4b |
|
360 kg N/ha |
114.2 |
190.0 |
235.8 |
180.0a |
|
540 kg N/ha |
145.0 |
219.2 |
239.2 |
201.3a |
|
Average |
117.8c |
186.1b |
211.7a |
|
1 Values with same letter horizontally are not statistically different, P <0.05 (Duncan, 1955).CONCLUSIONS
From the evaluations carried out for more than 14 years on shrub and tree forages at CATIE, mulberry is one of the best for ruminant feeding. Its high levels of CP and digestibility are far superior to those of most commonly used tropical forages and are comparable to concentrates.
The plant shows a high capacity to shoot and to survive up to two years. The results show that with adequate fertilization, mulberry produces high edible biomass yields per unit area. The levels of production shown in these trials exceed any data in the literature from temperate climates in Asia and South America.
With adequate fertilization, yields increase with time as shown in the studies reviewed. Because of its effect on soil physics and the presence of other nutrients, animal manure is superior to ammonium nitrate in terms of yield per unit area. Although mulberry extracts a lot of nutrients from the soil, it is very efficient in their utilization when applied organically, particularly in the case of nitrogen.
Nutrient yield is greater with more frequent cuttings, however the most appropriate cutting frequency should be determined for each site depending on soil conditions, fertilization and rainfall.
RECOMMENDATIONS
Several agronomic management factors must be studied in the future, according to the various production systems and ecological and topographic conditions at each site. Above all, evaluations need to be made on the effect that certain factors can have on sustainability and soil conservation. The following are certain criteria and recommendations along these lines.
Pruning
Information exists on the effect of cutting height on DM yields but, in some cases, it is contradictory and preliminary (Benavides, 1986; Blanco, 1992). Because of the effect that cutting height seems to have on leaf:stem proportion, it is important to validate this research in new studies and under different conditions.
In plantations destined to the production of forage for ruminants, the frequency has been studied for humid tropical conditions. However, it is in the dry tropics where this factor could be more relevant. Under these conditions, it is possible that cutting should be determined by rainfall patterns specifically for each place. Plant height could be the criteria for harvesting.
According to the literature, the number of main branches maintained when pruning has important effects on biomass yields. However, these studies refer to the use of mulberry for feeding the silkworm, and there is no information for its application in plantations to produce forage for ruminants.
One of the main problems of tropical livestock husbandry is feeding during the dry period. With regard to this, it is recommended to conduct studies on the effect of pruning at the end of the dry season on yields during the dry period.
Other constraints for the use of this plant in large plantations could be the lack of mechanical harvesting and manure spreading techniques. These are not a problem for small producers.
Planting
The planting period is more important in the dry tropics than in areas with well-distributed rainfall. This has received little attention, yet it is possible that it exerts on root development and seed survival.
Planting distance has been studied under bimodal rainfall conditions in Guatemala, where higher densities yield more biomass. However, this type of study needs to be continued to discover its effect on production persistence. Obviously, spacing will depend on whether mulberry is planted as a monoculture or in association.
According to field observations, it is possible that mulberry stakes could be placed horizontally, saving planting material and labour.
The development of planting systems on slopes is of great importance for appropriate soil use and protection, since erosion problems are very serious in the region.
One of the greatest difficulties in small- and medium-size farms is to convince owners to substitute crops for forages. In this case, evaluation of associations of mulberry with other crops could allow greater total productivity without affecting the yield of traditional crops.
Fertilization
Without doubt the most important constraint for mulberry production is its high dependency on soil nutrients. For this reason fertilization has received special attention in CATIE’s work. However, much remains to be done, in particular by using other organic fertilizers and associations with other nitrogen fixing plants. Although high yields can be expected with chemical fertilizers, their use may be restricted by cost and possible environmental impact. Associations with herbaceous and tree legumes in order to use the foliage as green manure could be an interesting alternative. In particular trees might be considered because of their capacity for soil retention and nutrient recycling.
Evaluations of species and varieties
Several species or varieties of mulberry are being planted in different locations and countries. However, comparative studies on the advantages and disadvantages of each, depending on climate and soil type, have not been made. Breeding and selection of species and varieties are one of the most important disciplines for mulberry, in particular because of its high forage potential and the existence of a great deal of germplasm.
Forage conservation
Reiterating that it is in the dry areas with bimodal rainfall where mulberry can have the most relevant role, it is advisable to continue studies on ensiling techniques, in particular the means of reducing pH. Mixtures of mulberry and tropical grasses should also be evaluated in order to stabilize the silo and obtain a better quality product for animals in the dry season.
Economic evaluations
Although there is some information on the economics of mulberry production and use under humid tropical conditions (Rojas, 1992), it is necessary that research on mulberry also includes an economic analysis as an important factor to define recommendations for mulberry use.
BIBLIOGRAPHY
Ammour, T. & Benavides, J.E. 1987. Situación de la producción caprina en Centroamérica y República Dominicana. Technical Report. No. 114. Turrialba, Costa Rica, CATIE. 117 pp.
Araya, J. & Benavides, J.E. 1992. Efecto de la procedencia, posición en la rama y tipo de siembra en el establecimiento de estacas de Sauco Amarillo (Sambucus canadensis) en Puriscal, Costa Rica. In Seminario Centroamericano de Agroforestería y Rumiantes Menores (1. 1992, Chiquimulas, Guatemala). Memorias. (unpublished)
Araya, J., Benavides, J.E., Arias, R. y Ruiz, A. 1993. Identificación y caracterización de árboles y arbustos con potencial forrajero en Puriscal, Costa Rica. In Seminario Centroamericano y del Caribe sobre Agroforestería y Rumiantes Menores. Memorias, Turrialba, Costa Rica, Comisión Nacional para el Desarrollo de la Actividad Caprina.
Arias, R. 1987. Identificación y caracterización de los sistemas de producción caprina, predominantes en la región del Altiplano Occidental de Guatemala. Turrialba, Costa Rica UCR/CATIE. 155 pp. (thesis)
Ávila, M., Navarro L.A. & Lagemann J. 1982. Improving the small farm production systems in Central America. In Memorias XVIII Conferencia Internacional de Economistas, Jakarta, Indonesia, Turrialba, Costa Rica, CATIE.
Benavides, J.E. 1986. Efecto de diferentes niveles de suplementación con follaje de morera (Morus sp.) sobre el crecimiento y consumo de corderos alimentados con pasto (Pennisetum purpureum). In Resumen de las investigaciones realizadas con rumiantes menores, cabras y ovejas. Proy. Sistemas de Producción Animal, p.40-42. Technical Report No. 67. Turrialba, Costa Rica, CATIE.
Benavides, J.E. 1989. La producción caprina como un componente en sistemas agroforestales. Turrialba, CATIE, Programa Agroforestal. 90 pp.
Benavides, J.E. 1991. Integración de árboles y arbustos en los sistemas de alimentación para cabras en América Central: un enfoque agroforestal. El Chasqui (Costa Rica), 25: 6-35.
Benavides, J.E. 1993. Utilización del poró (Erythrina sp.) en sistemas agroforestales con rumiantes menores. In Erythrina: management and improvement. Proceedings of a Workshop held at CATIE, Turrialba, Costa Rica. Nitrogen Fixing Tree Association Special Publication.
Benavides, J.E., Borel, R. & Esnaola, M.A. 1986. Evaluación de la producción de forraje del árbol de morera (Morus sp.) sometido a diferentes frecuencias y alturas de corte. In Resumen de las investigaciones realizadas con rumiantes menores, en el Proyecto de Sistemas de Producción Animal. Technical Report No. 67. Turrialba, Costa Rica, CATIE. pp. 74-76.
Benavides, J.E., Lachaux, M. & Fuentes, M. 1994. Efecto de la aplicación de estiércol de cabra en el suelo sobre la calidad y producción de biomasa de Morera (Morus sp.). In: J.E. Benavides, ed. Árboles y arbustos forrajeros en América Central, p.495-514. Technical Report No. 67. Turrialba, Costa Rica, CATIE.
Benavides, J.E. & Pezo, D. 1986. Evaluación del crecimiento y del consumo de materia seca en corderos alimentados con follaje de Poró (Erythrina poeppigiana) ad lib., suplementados con diferentes fuentes de energía. In Centro Agronómico Tropical de Investigación y Enseñanza. Resumen de las investigaciones realizadas con rumiantes menores, cabras y ovejas, Technical Report No. 67. Turrialba, Costa Rica, CATIE
Benavides, J.E., Rodriguez, R.A. & Borel, R. 1989. Producción y calidad nutritiva del forraje de pasto King-grass (Pennisetum purpureum x P. typhoides) y Poró (Erythrina poeppigiana) sembrados en asociación. In A. Xande & G. Alexandre, eds. Symposium sur l'alimentation des ruminants en milieu tropical). Pâturages et alimentation des ruminants en zone tropicale humide. p. 367-376. INRA, Station de Recherches Zootechniques.
Collins, M., 1990. The last rain forests. London, Mitchell Beazley Publishers. IUCN. 200 pp.
Coto, O.M. 1996. Importancia nutritiva de la Morera (Morus alba). San Andrés, El Salvador, Centro Nacional de Tecnología Agropecuaria y Forestal. Ministerio de Agricultura y Ganadería. 6 pp. (mimeo).
Cubillos, G., Vonhout, K. & Jiménez, C. 1975. Sistemas intensivos de alimentación del ganado en pastoreo. In El potencial para la producción del ganado de carne en América Tropical. p. 125-142. CS-10 Series. Cali, Colombia, CIAT.
Esperance, M. & Guerra, A. 1978. Efecto de diferentes niveles de suplementación de heno y concentrados en dietas de ensilajes ad libitum y pastoreo restringido para la producción de leche. Revista Cubana de Ciencia Agrícola, 12(3): 213-223.
Espinoza, E. 1996. Efecto del sitio y de la fertilización nitrogenada sobre la producción y calidad de la biomasa de tres variedades de Morera (Morus alba). Costa Rica, CATIE. 86 pp. (thesis)
Espinoza, E. & Benavides, J.E. 1996. Efecto del sitio y de la fertilización nitrogenada sobre la producción y calidad del forraje de tres variedades de Morera (Morus alba L.). Agroforestería de las Américas (CATIE), 3(11-12): 24-27.
Esquivel, J. 1993. Efecto de la posición de la estaca en la siembra de Morera (Morus sp.), Amapola (Malvaviscus arboreus) y Sauco Amarillo (Sambucus canadensis) sobre la germinación. In Seminario Centroamericano y del Caribe sobre Agroforestería y Rumiantes Menores. (2., 1993, San José, Costa Rica). Memorias. Turrialba, Costa Rica.
Esquivel, J., Benavides, J.E., Hernández, I., Vasconcelos, J., González, J. y Espinoza, E. 1996. Efecto de la sustitución de concentrado con Morera (Morus alba) sobre la producción de leche de vacas en pastoreo. In Taller Internacional "Los árboles en la producción ganadera". Resúmenes, p.25. Matanzas, Cuba, EEPF "Indio Hatuey", Matanzas, Cuba. p. 25.
FAO. 1988. Mulberry cultivation. FAO Agricultural Services Bulletin No. 73/1. Rome. 127 pp.
FAO. 1990. Sericulture training manual. FAO Agricultural Services Bulletin No. 80. Rome. 117 pp.
Faustino, J. 1992. Efectos de la erosión hídrica y conservación de suelos en parcelas con pastos y árboles forrajeros. In Seminario Internacional de Investigación en Cabras. Memorias.
Garríguez, R.L. 1983. Sistemas silvopastoriles en Puriscal. In El componente arbóreo en Acosta y Puriscal, Costa Rica. p. 85-89. J. Heuveldop & L. Espinoza, eds. Turrialba, Costa Rica.
Godier, S., Medina, J.M., Brunschwig, G. & Waelput, J-J. 1991. Comportamiento alimenticio de un rebaño de cabras al pastoreo en una finca tradicional de la región Sur de Honduras. In Seminario Internacional de Investigación en Cabras Memoria. El Zamorano, Honduras, Secretaría de Recursos Naturales Dirección General de Ganadería.
González, F., 1951. El gusano de seda y la Morera. 4th ed. Cartillas Rurales No. 4, Servicio de capacitación y propaganda. Publicaciones del Ministerio de Agricultura. Madrid. 272 pp.
González, J. 1996. Evaluación de la calidad nutricional de la Morera (Morus sp.) fresca y ensilada, con bovinos de engorda. Turrialba, Costa Rica, CATIE. 84 pp. (thesis)
González, J., Benavides, J.E., Kass, M., Olivo, R. & Esperance, M. 1996. Evaluación de la calidad nutricional de la Morera (Morus alba L.) fresca y ensilada, con bovinos de engorda. Agroforestería de las Américas (CATIE). 3(11-12): 20-23.
Hernández, S. & Benavides, J.E. 1993. Caracterización del potencial forrajero de especies leñosas de los bosques secundarios de El Petén, Guatemala. In Seminario Centroamericano de Agroforestería y Rumiantes Menores. Memorias.
Heuveldop, J. & Chang, B. 1981. Agroforestry for improvements of deforested mountains lands in Costa Rica: a pilot study. Seventh IUFRO World Congress, Kyoto, Japan, 6-12 September 1981. Turrialba. 6 pp.
Jansen, D.H. & Martin, P.S. 1982. Neotropical anachronisms: the fruits the gomphotheres ate. Science (Washington), 215(1): 19-27.
Jegou, D., Waelput, J. J. & Brunschwig, G. 1994. Consumo y digestibilidad de la materia seca y del nitrógeno del follaje de Morera (Morus sp.) y Amapola (Malvabiscus arboreus) en cabras lactantes. In J.E. Benavides ed. Árboles y arbustos forrajeros en América Central, Vol. I. Technical Report No. 236. Turrialba, Costa Rica. CATIE. p. 155-162.
Jiménez, R. 1983. Situación forestal y medidas proteccionistas. In J. Heuveldop & L. Espinoza, eds. El componente arbóreo en Acosta y Puriscal, Costa Rica. p. 27-32. Costa Rica. CATIE.
Libreros, H.F., Benavides, J.E., Kass, D. & Pezo, D. 1994a. Productividad de una plantación asociada de Poró (Erythrina poeppigiana) y King Grass (Pennisetum purpureum x P. typhoides). I. Efecto de la adición de follaje al suelo sobre la producción y calidad de la biomasa. In J.E. Benavides, ed. Árboles y arbustos forrajeros en América Central. Vol. I. Technical Report No. 236. Turrialba, Costa Rica, CATIE.
Libreros, H.F., Benavides, J.E., Kass, D. & Pezo, D. 1994b. Productividad de una plantación asociada de Poró (Erythrina poeppigiana) y King Grass (Pennisetum purpureum x P. typhoides) II. Movilización de minerales. In: J.E. Benavides ed. Árboles y arbustos forrajeros en América Central. Vol. I. Serie técnica, Informe técnico No. 236. Turrialba, C.R. CATIE. pp.
López, G.Z., Benavides, J.E. Kass, M. & Faustino, J. 1993b. Efecto de la frecuencia de poda y la aplicación de estiércol sobre la producción de biomasa de Amapola (Malvaviscus arboreus). In Seminario Centroamericano y del Caribe sobre Agroforestería y Rumiantes Menores. (2. 1993, San José, Costa Rica). Memorias. Turrialba, Costa Rica. Comisión Nacional para el Desarrollo de la Actividad Caprina. (Unpublished)
López, G.Z., Benavides, J.E. Kass, M. & Faustino, J. 1993. Efecto de la suplementación con follaje de Amapola (Malvaviscus arboreus) sobre la producción de leche en cabras estabuladas. In Sem. Centroamericano y del Caribe sobre Agroforestería y Rumiantes Menores. (2. 1993, San José, Costa Rica). Memorias. Turrialba, Costa Rica. Comisión Nacional para el Desarrollo de la Actividad Caprina. (Unpublished)
Martínez, E. & Froemberg, H. 1992. Información económica sobre la actividad caprina con pequeños agricultores en Puriscal, Costa Rica. In Seminario Centroamericano de Agroforestería y Rumiantes Menores. Memorias. (Unpublished)
Mendizábal, G., Arias, R., Benavides, J.E., Rios, E. & Marroquin, F. 1993. Utilización del follaje de plantas silvestres en la alimentación de rumiantes, en el Altiplano Occidental de Guatemala. 33 p. (Unpublished)
Meza, T.A. & Bonilla, H. 1990. Áreas naturales protegidas de Costa Rica. Cartago, Costa Rica, Ed. Tecnológica de Costa Rica. 320 pp.
Minson, D.J. & McLeod, M.N. 1970. The digestibility of temperate and tropical grasses. Proc. XI Int. Grassl. Congr., Surfers Paradise, Qnd, Australia, 719-722.
Morales, M.A. 1983. Preferencias alimenticias entre dos especies de herbívoros (ganado vacuno y venado cola blanca). In F.P.G. Aguilar, ed. Conservación y manejo de la fauna silvestre en Latinoamérica. p.99. Symposium, Simposio, 10-11 October. 1983, Arequipa, Perú). Contribuciones. Aguilar F, P.G., Ed. Lima, Perú. WWF/APECO. p.99
Narimatsu, S. & Kiyoshi, K. 1975. Manual para la cría del gusano de seda. Japan International Cooperation Agency (JICA). Technical Book. Series No. 20. 78 p.
National Geographic Society. 1992. The coexistence of indigenous peoples and the natural environment in Central America. (map)
Oviedo, J.F. 1995. Morera (Morus sp.) en asocio con Poró (Erythrina poeppigiana) y como suplemento para vacas lecheras en pastoreo. Turrialba, Costa Rica, CATIE. 86 pp. (thesis).
Oviedo, F. & Benavides, J.E. 1994. Utilización del follaje de Morera (Morus sp.) en la suplementación de vacas y terneras de lechería en pastoreo. In Taller Internacional sobre Sistemas Silvopastoriles en la Producción Ganadera. Memorias, p. 18 Matanzas, Cuba. Estación Exp. de Pastos y Forrajes "Indio Hatuey".
Oviedo, F. J., Benavides, J.E. & Vallejo, M. 1994. Evaluación bioeconómica de un módulo agroforestal auto sostenible con cabras lecheras en Turrialba, Costa Rica. In: J.E. Benavides ed. "Árboles y arbustos forrajeros en América Central". Vol. II. Serie técnica, Informe técnico No. 236. Turrialba, Costa Rica. CATIE. pp. 601-630.
Reyes, E. & Medina, J.M. 1992. Comportamiento alimenticio de cabras pastoreando y ramoneando en un sitio de matorral de la zona Sur de Honduras. In Seminario Centroamericano de Agroforestería y Rumiantes Menores. Memorias.
Reyes, E. J. & Medina, J. M. 1993. Identificación de especies y caracterización de las actividades de cabras pastoreando y ramoneando en sitios con arbustivas de la Zona Sur de Honduras. In Seminario Centroamericano y del Caribe sobre Agroforestería y Rumiantes Menores. (2. 1993, San José, Costa Rica). Memorias. Turrialba, Costa Rica.
Rojas, H. 1992. Análisis económico de la producción de leche de cabras alimentadas con diferentes niveles de Morera (Morus sp.) como suplemento al King grass (Pennisetum purpureum x P. typhoides). Univ. Estatal a Distancia. Costa Rica. (draft thesis)
Rojas, H., Benavides, J.E. & Fuentes, M. 1994. Producción de leche de cabras alimentadas con pasto y suplementadas con altos niveles de Morera. In J.E. Benavides, ed. Árboles y arbustos forrajeros en América Central, pp. 305-320. Vol. II. Technical Report No. 236. Turrialba, Costa Rica, CATIE.
Rojas, J., Vallejo, M. & Benavides, J.E. 1992. Observaciones sobre la producción de biomasa de Jocote (Spondias purpurea) y Clavelón (Hibiscus rosa-sinensis) en la época de sequía según diferentes intervalos de poda. In Seminario Centroamericano de Agroforestería y Rumiantes Menores (1. 1992, Chiquimulas, Guatemala). Memorias.
Ruiz, R.F. 1992. Manejo de leñosas con potencial forrajero en el departamento de San Marcos, Guatemala. In Seminario Centroamericano de Agroforestería y Rumiantes Menores (1. 1992, Chiquimulas, Guatemala). Memorias.
Samur, C. 1984. Producción de leche de cabras alimentadas con King-grass (Pennisetum purpureum) y Poró (Erythrina poeppigiana) suplementadas con fruto de banano (Musa sp. cv. Cavendish). Turrialba, Costa Rica, CATIE/UCR. 51 pp.
Sands, M.W. 1983. Las cabras y la desertificación. In Curso Intensivo de Producción Caprina. Turrialba, Costa Rica, CATIE. 23 pp.
Skerman, P.J., Cameron, D.G. & Riveros, F. 1991. Tropical forage legumes. Rome, FAO. 707 pp.
Skerman, P.J. & Riveros, F. 1992. Tropical grasses. Rome. FAO. 850 pp.
Stobbs, T.H. 1975. Factors limiting the nutritional value of grazed tropical pastures for beef and milk production. Tropical Grasslands, 9(2): 141-150.
Strehle, U., Granados, A., Vallejo, M. & Benavides. J.E. 1992. Efecto de la especie y de la posición en el tallo sobre la germinación de estacas de Tora Blanca y Tora Morada (Verbesina sp.) en Puriscal, Costa Rica. In Seminario Centroamericano de Agroforestería y Rumiantes Menores
Tosi Jr, J.A. & Voertman, R.F. 1977. Máximo aprovechamiento de los bosques. México. Bosque y fauna, 14(1): 18-30. Also in Unasylva, 27: 110 (1975).
UNESCO. 1979. Tropical grazing land ecosystems. France, UNESCO/FAO. 665 pp.
Vallejo, M.A. 1995. Efecto del premarchitado y la adición de melaza sobre la calidad del ensilaje de diferentes follajes de árboles y arbustos tropicales. Turrialba, Costa Rica, CATIE. 98 pp. (thesis)
Vallejo, M, Benavides, J.E., Kass, M., Jiménez, C.M. & Ruiz, A. 1994. Evaluación preliminar de la calidad y el consumo de ensilajes de leñosas forrajeras. In Taller Internacional sobre Sistemas Silvopastoriles en la Producción Ganadera. Memorias, p. 25. Matanzas, Cuba, 13-15 December 1994. Estación Experimental de Pastos y Forrajes "Indio Hatuey".
