Mulberry: an exceptional forage available almost worldwide

M.D. Sánchez

The author is Animal Production Officer (Animal Nutrition), Animal Production Service, Animal Production and Health Division, FAO, Viale delle Terme di Caracalla, Rome, Italy. E-mail: [email protected]

LE MÛRIER: UN FOURRAGE EXCEPTIONNEL DISPONIBLE DANS PRESQUE TOUTES LES RÉGIONS DU MONDE

Le mûrier (Morus spp), aliment traditionnel du ver à soie, a été choisi et amélioré pour la qualité et le rendement de ses feuilles dans de nombreux milieux, et il est présent dans presque toutes les régions du monde. Les feuilles de mûrier sont extrêmement appétibles et digestes (70 à 90 pour cent) pour les herbivores et peuvent aussi être données aux monogastriques. La teneur en protéines des feuilles et des jeunes pousses, qui ont un bon profil d'acides aminés essentiels, varie entre 15 et 28 pour cent, selon la variété. La teneur en sels minéraux est élevée et on n'a pas détecté de facteurs antinutritionnels ou de composés toxiques. La plantation de ce fourrage pérenne s'effectue par semis ou bouturage, et la récolte par cueillette des feuilles ou par coupe de branches ou de pousses entières. Les rendements dépendent de la variété, de l'emplacement (température mensuelle, ensoleillement et pluviométrie), de la densité des plants, de la fumure et de la technique de récolte mais, en ce qui concerne les éléments nutritifs digestes, le mûrier est plus productif que la plupart des fourrages traditionnels. Les feuilles peuvent être données comme supplément à la place des concentrés aux vaches laitières, comme fourrage principal aux caprins, ovins et lapins, et en mélange avec d'autres ingrédients, aux monogastriques.

MORERAS: FORRAJE EXCEPCIONAL DISPONIBLE CASI EN TODO EL MUNDO

Las moreras (Morus spp.), alimento tradicional de los gusanos de seda, se han seleccionado y mejorado en el rendimiento y la calidad de las hojas en muchos ambientes y se han propagado por todo el mundo. Las hojas de morera son muy apetecibles y digestibles (70-90 por ciento) para los animales herbívoros, y también se pueden administrar a los monogástricos. El contenido de proteínas de las hojas y los tallos jóvenes, con un buen perfil de aminoácidos esenciales, oscila entre el 15 y el 28 por ciento, en función de la variedad. El contenido de minerales es alto y no se han identificado factores antinutricionales o sustancias tóxicas. Este forraje perenne se establece mediante estacas o semillas y se cosecha recogiendo las hojas o cortando ramas o tallos enteros. El rendimiento depende de la variedad, el lugar (temperatura mensual, radiación solar y precipitación), la densidad de plantas, la aplicación de fertilizantes y la técnica de recolección, pero la morera produce más nutrientes digestibles que la mayoría de los forrajes tradicionales. Las hojas se pueden utilizar como complemento en sustitución de los piensos concentrados para los vacunos lecheros, como principal pienso para las cabras, las ovejas y los conejos y como ingrediente en la alimentación de los animales monogástricos.

Mulberry germplasm research in Guanzhou Province, China
Recherche concernant le matériel génétique du mûrier dans la province de Guanzhou en Chine
Investigación sobre el germoplasma de morera en la provincia de Guanzhou, China
(M.D. Sánchez)

Mulberry (Morus spp.) leaves are the traditional food of the silkworm (Bombyx mori). There is evidence that sericulture started about 5 000 years ago (Huo Yongkang, South China Agricultural University, personal communication), leading to domestication of the mulberry. Mulberry has been selected and improved for leaf quality and yield for a long time. Through silk production projects, mulberry has been taken to countries all over the world: it has now spread from the temperate areas of northwestern and central Asia, Europe and North America, through the tropics of Asia, Africa and Latin America to southern Africa and South America. There are mulberry varieties for many environments, from sea level to altitudes of 4 000 m (FAO, 1990) and from the humid tropics to semi-arid regions such as the Near East, with 250 mm of annual rainfall, and the southwestern United States (Tipton, 1994). Mulberry is also produced under irrigation. Although the majority of silk production projects have had limited duration owing to silk processing constraints and limited market opportunities, mulberry trees have remained in most places where they were introduced.

Mixed farming systems with mulberry in Sichuan Province, China
Systèmes agricoles mixtes comprenant la culture du mûrier dans la province du Sichuan en Chine
Sistemas de cultivo mixto con moreras en la provincia de Sichuan, China
(M.D. Sánchez)

The main use of mulberry globally is as feed for the silkworm. Depending on the location, however, it is also appreciated for its fruit, consumed fresh, as juice or as preserves. The young leaves and stems are a delicious vegetable and infusions such as mulberry leaf tea have medicinal properties. It is also used for landscaping and as animal feed. In Peru, the multiple uses of mulberry have been recognized (Zepeda, 1991). There are several places where mulberry is utilized traditionally as a feed in mixed forage diets for ruminants, as in certain areas of India, China and Afghanistan. In Italy there have been several studies on the use of mulberry for dairy cows and other domestic animals (Vezzani, 1938; Maymone, Tiberio and Triulzi, 1959; Bonciarelli and Santilocchi, 1980; Talamucci and Pardini, 1993). In France a research project was carried out on the introduction of mulberry in livestock production (Armand and Meuret, 1995). It was only in the 1980s, however, that specific interest in the intensive cultivation and use of mulberry as animal feed started in Latin America. It is surprising that a plant that has been improved for leaf quality and yield to feed the silkworm, an animal with high nutritional feed requirements, has received limited attention from livestock producers, technicians and researchers.

Mulberry grown under irrigation in the state of San Luis Potosí, Mexico
Culture irriguée de mûriers dans l'État de San Luis Potosí au Mexique
Moreras cultivadas en regadío en el estado de San Luis de Potosí, México
(M.D. Sánchez)

Like other significant breakthroughs in science and technology, the discovery of the value of mulberry as a high-quality feed in Latin America happened by chance. A Costa Rican farmer of Chinese origin, whose silk project had failed, fed mulberry leaves to his goats and was impressed by its palatability and by the performance of his animals. He communicated his observations to scientists of the Tropical Agriculture Research and Higher Education Center (CATIE), who were interested by the information. They subsequently included mulberry in their tree fodder evaluations and later in agronomic and animal performance trials (J. Benavides, personal communication). In Africa, the International Centre for Research in Agroforestry (ICRAF) in Kenya and the Livestock Production Research Institute in the United Republic of Tanzania have conducted successful agronomic and animal trials, apparently without being aware of the interest elsewhere.

Collection of mulberry varieties in Galia, São Paolo, Brazil
Collection de variétés de mûriers à Galia à São Paulo au Brésil
Recolección de variedades de morera en Galia, São Paulo, Brasil
(M.D. Sánchez)

GENETIC RESOURCES

Mulberry belongs to the Moraceae family (subtype angiosperms, class dicotyledons, subclass urticales). There are several species, such as Morus alba, M. nigra, M. indica, M. laevigata and M. bombycis, which have been used directly or through crossings and induced mutations for the development of varieties to support silkworm production. The diploid M. alba (2n = 2x = 28) is the most widespread species, but polyploid varieties, which originated in various research stations in Asia, show greater leaf yields and quality. In general, polyploid varieties have thicker and larger leaves of a darker green colour and produce more leaves. There is a large variation in leaf production and leaf quality, for example protein content, among the many species and in the varieties and cultivars grown at different locations under a wide range of soil and environmental conditions, indicating the huge potential for identifying suitable germoplasm for most sites.

Gliricidia-mulberry forage bank in the Cauca Valley, Colombia
Berge du Valle del Cauca en Colombie occupée par des cultures fourragères de gliricidia-mûrier
Parcela de forraje de Gliricidia-morera en el Valle del Cauca, Colombia
(M.D. Sánchez)

Many of the references to mulberry in the literature do not specify species or varieties; often, names are given based on leaf features. In many cases, locally grown varieties (native or criolla) seem to perform adequately, since they are probably well adapted to local conditions.

COMPOSITION AND NUTRITIVE VALUE

Results of chemical composition of mulberry fractions from various authors are presented in Table 1.

1
Chemical composition (% of dry matter) of mulberry
Composition chimique du mûrier (pour cent de la matière sèche)
Composición química (% de materia seca) de la morera

¹ Names of places where local varieties were used.
² September 1982.
³ November 1983.
CP = crude protein; CF = crude fibre; NDF = neutral fibre detergent; ADF = acid detergent fibre; EE = ether extract; P = phosphorus.

Crude protein content in leaves varies from as low as 15 percent to 28 percent, depending on the variety, age of the leaves and growing conditions. In general, crude protein values can be considered similar to most legume forages. Fibre fractions are low in mulberry leaves compared with other foliages. Shayo (1997) reported lignin (acid detergent lignin) contents of 8.1 percent for leaves and 7.1 percent for bark. A striking feature of mulberry leaves is the mineral content, with ash values up to 25 percent. Typical calcium contents are around 1.8 to 2.4 percent and phosphorus 0.14 to 0.24 percent. Espinoza, Benavides and Ferreire (1999) found potassium values of 1.90 to 2.87 percent in leaves and 1.33 to 1.53 percent in young stems; magnesium contents were 0.47 to 0.63 percent for leaves and 0.26 to 0.35 percent for young stems.

Table 2 shows the digestibility of mulberry. As can be seen, leaf digestibilities in vivo (goats) and in vitro are very high (> 80 percent) and, overall, digestibility is equivalent to that of most tropical forages.

2 
Digestibility of mulberry
Digestibilité du mûrier
Digestibilidad de la morera

The degradation characteristics of mulberry, determined by the nylon bag technique, are presented in Table 3. Leaves would be completely degraded if they remained in the rumen for long enough.

3 
In sacco degradation of mulberry
Dégradation in sacco du mûrier (ITA n^o 2, 1998)
Degradación in sacco de la morera

Source: ITA#2 (1998).

The average amino acid composition and nitrogen content of 119 mulberry varieties grown experimentally in Japan (Machii, 1989) are presented in Table 4. Tryptophane was not included in the analysis. As can be seen from the data, essential amino acids are nearly 46 percent of total amino acids. It can be calculated from the table that the average nitrogen (N) is 16.6 percent of the total molecular weight of the mulberry amino acids plus ammonia; the converting factor from N to mulberry protein is thus 6.02. The 204.3 mg of amino acids per gram of protein is equivalent to 3.47 percent N, which is 80 percent of total N in mulberry leaves. Once tryptophane is subtracted, the difference, a non-protein fraction, is likely to be composed of nucleic acids and other unidentified N compounds.

4 
Average amino acid composition and N content of mulberry varieties (Machii, 1989) and soybean meal
Composition moyenne des acides aminés et teneur en N des variétés de mûriers (Machii, 1989) et du tourteau de soja (NRC, 1984)
Composición media de aminoácidos y contenido de nitrógeno de diversas variedades de morera y de la harina de soja

¹ Percentage of the amino acid in the total sum of amino acids (plus ammonia).
² Not available.
³ Without tryptophane.
Source: NRC (1984).

The most important protein in mulberry leaves, as in most leaves, is ribulose-1,5-bisphosphate carboxylase (RuBisCO) whose active site is responsible for carbon fixation (Kellogg and Juliano, 1997). N in RuBisCO can be 43 percent of the total N in mulberry (Yamashita and Ohsawa, 1990).

Palatability

One of the main features of mulberry as forage is its high palatability. Small ruminants avidly consume the fresh leaves and the young stems first, even if they have never been exposed to it before. Then, if the branches are offered unchopped, they might tear off and eat the bark. Cattle consume the whole biomass if it is finely chopped. There is a report (Jegou, Waelput and Brunschwig, 1994) of ad libitum dry matter (DM) intake of 4.18 percent of live weight, the average of three lactating goats, which is much higher than with other tree fodders. Jayal and Kehar (1962) reported dry matter intakes of mulberry leaves of 3.44 percent of body weight in sheep under experimental conditions. Animals initially prefer mulberry over other forages when they are offered simultaneously, and even dig through a pile of various forages to look for mulberry (Antonio Rota, FAO Barbados, personal communication). In a comparative study, Prasad and Reddy (1991) reported higher daily dry matter intakes of mulberry leaves in sheep than in goats - 3.55 as opposed to 2.74 kg DM/100 kg body weight.

Dairy goats consuming mulberry leaves in a zero-grain system in Turrialba, Costa Rica
Chèvres laitières consommant des feuilles de mûrier dans un système de stabulation permanente à Turrialba au Costa Rica
Cabras lecheras comiendo hojas de morera en un sistema sin grano en Turrialba, Costa Rica
(M.D. Sánchez)

AGRONOMY

Establishment

The most common planting method worldwide is by stem cuttings, although in certain places seed is preferred. As with other tropical perennial forages for cut-and-carry systems, planting by seed assures deeper roots with greater capacity to find water and nutrients, which eventually results in higher biomass production and greater longevity. Seeds might be the most acceptable way of transporting quarantine and store selected materials. The advantages of stem reproduction, or cloning, are certainty of production characteristics, practicality in obtaining the material and ease of planting. Male plants might be preferred when introducing foreign germplasm to new locations, since this prevents involuntary expansion (Morgan P. Doran, University of California, Davis, United States, personal communication). As in most perennial forages, the time and the establishment cost, mainly for land preparation, planting and weed control, are the critical aspects of the successful introduction of mulberry.

Cultivation

Mulberry is cultivated as follows:

• for fruit, as isolated trees or in orchards;
• for small-scale silkworm rearing, along the edges or among food crops in mixed farming systems;
• for large silk projects or for intensive forage production, in pure stands;
• for forage in association with N-fixing legumes (Talamucci and Pardini, 1993; González and Mejía, 1994).

Mulberry is also found mixed with other trees in natural forests or plantations.

Fertilization

All the required nutrients for mulberry growth must come from the soil, since it does not fix atmospheric N. In pure stands, mineral and organic fertilizers - animal and vegetable manures - must be used to replenish the nutrients removed with the foliage in order to maintain a sustainable production. The association with legumes with effective N-fixing rhizobium can reduce N inputs and may be the most desirable combination for some farms. Even when recycling nutrients in animal manures, however, extra chemical fertilizers are required for maximum yields (J.E. Benavides, personal communication). Responses of mulberry to N fertilizers have been clearly demonstrated, both in inorganic and organic forms, with better responses to the latter (Table 5). According to Kamimura et al. (1997), the N level in soils is the major factor for mulberry growth.

5
Effect of goat manure or ammonium nitrate application on total dry matter yields over three years
Effet de l'application de fumier de chèvre ou de nitrate d'ammoniaque sur les rendements totaux en matières sèches pendant trois années consécutives (Benavides et al., 1994)
Efecto de la aplicación de estiércol de cabra o nitrato de amonio en el rendimiento total de materia seca durante tres años consecutivos

¹1 kg N/ha/year.
² Values with the same letter horizontally do not differ (p > 0.001).
Source: Benavides, Lachaux and Fuentes (1994).

Harvest and preservation

For silkworm feeding, individual leaf picking, shoot harvesting and whole branch cutting are practised, depending on the feed requirements of silkworm larvae stages and on harvesting costs (FAO, 1988). For silkworms, leaves are offered fresh, but some other forms of feeding are being developed. For ruminant feeding, the preferred method has been branch cutting by hand, although mechanical harvesting could be employed in the future for direct feeding of fresh material on a large scale, for processing or for drying. Forage conservation by ensiling has been successfully achieved (Vallejo, 1995; González, 1996, cited by Benavides, 1999) and there have been some preliminary studies on leaf drying (Ojeda et al., 1998). Leaf blades dry within hours under full sun but more time is required for petioles and stems. Some conditioning, for example passing them through rollers, may help to reduce water content and minimize the deterioration of leaf quality by over exposure. Diploid varieties dry faster since they tend to have more stomata per unit of leaf area (Govindan, Narayanaswamy and Magadum, 1988).

Yields

The production of leaf and total dry matter per hectare of mulberry depends on the variety, location, plant density, fertilizer applications and harvesting techniques. Table 6 presents the yields of mulberry in various locations. Total biomass yield and the leaf proportion vary with species and varieties. Climate - moisture and solar radiation - and soil fertility are determining factors on productivity (Espinoza, Benavides and Ferreire, 1999). Increasing planting density increases leaf yields (Gong, Ren and Wang, 1995). Fresh leaf yields of 40 tonnes per hectare per year, approximately 10 tonnes of dry matter, have been reported in India (Mehla, Patel and Tripathi, 1987) and in Costa Rica (Espinoza, Benavides and Ferreire, 1999). Maximum dry matter yields of edible material - leaves and young stems - and total biomass were 15.5 and 45.2 tonnes per hectare per year, respectively. Total leaf dry matter yields of less than 10 tonnes could be expected under less intensive production.

6
Examples of mulberry yields
Exemples de rendements des mûriers
Ejemplos de rendimiento de moreras

ANIMAL PERFORMANCE WITH MULBERRY

Ruminants

Although the feeding value of mulberry for dairy cattle has been recognized for some time in Italy (Vezzani, 1938; Maymone, Tiberio and Triulzi, 1959) and it has traditionally been used in Himalayan countries, the research on mulberry for ruminants has been rather limited. Jayal and Kehar (1962), working from the high digestibility values of M. indica leaves, suggested that they could be used as supplements for lower-quality forages. Mulberry was used to replace grain-based concentrates in lactating cows with excellent results (Table 7).

7
Substitution of concentrates by mulberry in lactating Holstein cows grazing Kikuyu grass (Pennisetum clandestinum)
Remplacement des concentrés par du mûrier chez des vaches Holstein en lactation paissant dans des pâturages d'herbe Kikuyu (Pennisetum clandestinum) (Esquivel et al., 1996)
Sustitución de piensos concentrados por morera en vacas Holstein lactantes pastoreadas en pasto kikuyo (Pennisetum clandestinum)

Source: Esquivel et al. (1996).

Yields did not significantly decrease when 75 percent of the concentrate was replaced with mulberry. Milk production increased with the levels of mulberry offered to goats on a King grass diet (Rojas and Benavides, 1994), as shown in Figure 1. At CATIE (Turrialba, Costa Rica), a module of two Saanen x Toggenburg dairy goats being fed exclusively with forage from 775 m² of mulberry (17 000 plants per hectare), in association with Erytrina berteroana (5 128 trees per hectare) as green manure, and from 425 m² of King grass, produced an average of 4 litres per day, equivalent to over 12 000 litres per hectare per year (Oviedo, Benavides and Vallejo, 1994).

Milk production in goats fed mulberry and King grass (kg/day)
Production laitière de chèvres nourries aux feuilles de mûrier et de Gliciridia sepium (kg/j)
Producción de leche en cabras alimentadas con hojas de morera y rabo de ratón

Also in Costa Rica, liveweight gains of bulls belonging to the Romosinuano breed, a criollo type, fed on elephant grass, increased to over 900 g per day when mulberry was offered as a supplement at 1.7 percent of their body weight on a DM basis (González, 1996 cited by Benavides, 1999). Table 8 presents the results of an experiment in Guatemala with growing Zebu x Brown Swiss steers being fed increasing levels of mulberry as supplement to a sorghum silage diet (Velázquez et al., 1994). Although the growing rates with the highest mulberry level are not impressive (195 g per day), most likely owing to the poor quality of the silage, this trial shows the high nutritive value of the supplement. Total intake and weight changes improved with the amount of mulberry offered, reflecting its higher nutritive value compared with the basal diet. Daily gains of female calves of up to four months were not affected when mulberry leaves were offered ad libitum and the commercial concentrate reduced to 25 percent of the amount traditionally used (González and Mejía, 1994). In lambs, gains reached 100 g per day when King grass was supplemented with 1.5 percent DM of mulberry (Benavides, 1986).

8
Effect of mulberry supplementation level on intake and weight changes of Zebu x Brown Swiss steers fed on sorghum silage
Effet du niveau de complémentation avec du mûrier sur la ration et les variations de poids de bouvillons issus de croisements entre des zébus et des vaches brunes des Alpes nourris d'ensilage de sorgho (Vélasquez et al., 1994)
Efecto del nivel de complementación con morera en el consumo y los cambios de peso de novillos Zebu x pardo suizo alimentados con ensilado de sorgo

¹ BW = body weight.
Source: Velázquez et al. (1994).

Monogastrics

The silkworm has a relatively simple digestive system. In certain ways it is comparable to that of the monogastric animals, so in theory mulberry leaves could also be used as one of the ingredients in monogastric diets. In a trial with growing pigs in which up to 20 percent of a commercial concentrate was replaced by mulberry leaf (Trigueros and Villalta, 1997), the best level of substitution was 15 percent. It increased daily gains from 680 to 740 g and also gave the best economic results. In rabbits, the reduction of the daily intake of concentrate, from 110 to 17.5 g with ad libitum fresh mulberry, reduced gains from 24 to 18 g per day but decreased to just over half the cost of the meat produced (Lara y Lara, Sanginés and Dzib, 1998).

The combination of a protein source of mulberry and Trichantera gigantea leaves and an energy source of blocks made of molasses, cassava root meal and rice bran gave better reproduction and growth performance than a diet of commercial concentrates and grass (Le Thu Ha et al., 1996). Singh, Goel and Negi (1984) supplemented Angora rabbits receiving pelleted diets with mulberry leaves ad libitum and obtained intakes of mulberry equivalent to 29 to 38 percent of the total intake. This level significantly reduced feed cost. Deshmukh, Pathak and Takalikar (1993) fed mulberry leaves as the sole ration to adult rabbits. They found daily intakes of 68.5 g for dry matter, 11.2 g for crude protein and 175 kcal for digestible energy, equivalent to 2.55 Mcal of digestible energy per kilogram. The digestibility values were 74 percent for crude protein, 59 percent for crude fibre and 64 percent for dry matter. The authors concluded that mulberry leaves provided enough nutrients for maintenance. Narayana and Setty (1977) found better egg yolk colour and increased egg size and production with the inclusion of up to 6 percent of shade-dried M. indica leaf meal in the mash of laying hens.

Other small herbivores, such as guinea pigs, iguanas and snails, could also be fed mulberry leaves. In fact, wild green iguanas (Iguana iguana) came to feed on recently established mulberry fields in Costa Rica (J.E. Benavides, personal communication).

Rabbits avidly consuming mulberry leaves in Yucatán, Mexico.
Lapins consommant avidement des feuilles de mûrier dans le Yucatán au Mexique
Conejos consumiendo ávidamente hojas de morera en Yucatán, México
(M.D. Sánchez)

LIVESTOCK PRODUCTION SYSTEMS

The traditional way of using mulberry as animal feed in silk-producing areas is by providing ruminants with the residue left by the silkworm. A model of sericulture and milk production has been proposed by Mehla, Patel and Tripathi (1987), in which dairy cows receive mulberry residue and concentrates. The production of edible protein and the generation of employment are much greater than with foodgrains. This refuse material is added to fishponds for herbivorous carp in the Chinese dyke-pond system, which is one of the most intensive agricultural low-input systems in the world, generating food and outputs for a large number of people (Korn, 1996). In these silk areas, as well as where mulberry grows wild, cut-and-carry systems are practised. This is the most obvious way of utilizing mulberry for livestock, either from pure stands or from associations with legumes (Benavides, Esquivel and Lozano, 1995). Mulberry foliage can constitute the supplement to low-quality grass-based diets or be used as the main component of the ration.

A natural association of mulberry and livestock occurs in regions such as the Near East and Central Asia where mulberry trees are kept for fruit production. Fallen leaves in the autumn are consumed by domestic animals. Since fruit ripening happens in late spring or early summer, it may be possible to harvest leaves for forage once or more before the winter.

The only suggestion of utilizing mulberry for direct grazing came from Talamucci and Pardini (1993), who proposed a complementary association with clover (Trifolium subterraneum) for sheep and cattle grazing in Tuscany, Italy. Mulberry benefits from the N fixation by the clover and contributes with high-quality forage during the summer. The association produces more forage over a longer period than the individual pure stands.

CONCLUSION

The net result of long selection and improvement of mulberry has been that it is comparable to or better than many other forage plants in terms of nutritional value and yield of digestible nutrients per unit of area, especially in tropical environments. Yield, quality and availability worldwide make mulberry a very important option to intensify livestock systems, especially in those places where enough nutrients can be applied to obtain maximum response in biomass production. The high mineral content of mulberry foliage should be specifically taken into account in nutrient recycling and fertilizing schemes to prevent loss of soil fertility.

Considering its high quality and palatability, the smaller the animals, the more valuable mulberry should be as a feed. Under equal circumstances, stock with higher nutrient requirements per kilogram of live weight should be given preference when feeding mulberry.

The greatest immediate impact of mulberry in animal production would be in tropical areas if introduced as supplement to lactating cows and as feed to growing calves. It could be grown near stables where simple harvesting and manuring practices could be implemented.

Bibliography

Armand, D. & Meuret, M. 1995. Culture en sec et utilisation en élevage de Morus alba "Kokuso 21"en Provence. Rapport Final (1991-1994). Selection and utilization of cultivated fodder trees and shrubs in Mediterranean extensive livestock production systems. Avignon, France, INRA.
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. Technical Series No. 67: 40-42. Turrialba, Costa Rica. CATIE.
Benavides, J.E. 1999. Utilización de la morera en sistemas de producción animal. In M.D. Sánchez & M. Rosales. Agroforestería para la producción animal en Latinoamérica. Memorias de la conferencia electrónica. FAO Animal Production and Health Paper No. 143. Rome, FAO.
Benavides, J.E., Esquivel, J. & Lozano E. 1995. Módulos agroforestales con cabras para la producción de leche. Guía técnica para extensionistas. Manual Técnico No. 18. Turrialba, Costa Rica, CATIE. 56 pp.
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. Arboles y arbustos forrajeros en América Central, p. 495-514. Volumen II. Turrialba, Costa Rica, CATIE.
Bonciarelli, F. & Santilocchi, R. 1980. Primi risultati di prove con arbusti forraggeri da pascilo. Rivista di Agronomía (Italia), 14: 21-29.
Casoli, C., Duranti, E., Damiani, P. & Rongoni, V. 1986. Composizione chimica e valore nutritivo di foglie di Morus alba. Zootecnia e Nutrizione Animales (Italia), 12: 47-54.
Deshmukh, S.V., Pathak, N.V. & Takalikar, D.A. 1993. Nutritional effect of mulberry (Morus alba) leaves as sole ration of adult rabbits. World Rabbit Science, 1(2): 67-69.
Espinoza, E., Benavides J.E. & Ferreire, P. 1999. Evaluación de tres variedades de morera (Morus alba) en tres sitios ecológicos de Costa Rica y bajo tres niveles de fertilización. Cited in Benavides, J.E. (1999).
Esquivel, J., Benavides, J.E., Hernández, I., Vasconcelos, J., González, J., & Espinoza, E. 1996. Efecto de la sustitución de concentrado con Morera (Morus alba) sobre la producción de leche de vacas en pastoreo. In Resúmenes. Taller Internacional "Los árboles en la producción ganadera". Matanzas, Cuba, EEPF Indio Hatuey.
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.
Gong, L., Ren, D.J. & Wang, Y. 1995. Studies on the solar energy utilization of mulberry fields with different planting densities. Sericologia, 35(3): 497-505.
González, J. 1996. Evaluación de la calidad nutricional de la Morera (Morus sp.) fresca y ensilada, con bovinos de engorda. Turrialba, Costa Rica, CATIE. (thesis, 84 pp)
González, E., Delgado, D. & Cáceres, O. 1998. Rendimiento, calidad y degradabilidad ruminal potencial de los principales nutrientes en el forraje de morera (Morus alba). In Memorias III Taller Internacional Silvopastoril Los árboles y arbustos en la ganadería, p. 69-72. 25-27 November 1998. Matanzas, Cuba, EEPF Indio Hatuey.
González, S.E. & Mejía, I. 1994. Utilización de la morera (Morus indica) como reemplazo parcial del concentrado en la crianza de terneras. Universidad Nacional de Colombia, Palmira, Colombia. (thesis)
Govindan, R., Narayanaswamy, T.K. & Magadum, S.B. 1988. Relative moisture loss from leaves of some mulberry varieties during storage. Current research (University of Agricultural Sciences, Bangalore), 17(11): 151-153.
ITA#2. 1998. Introducción y evaluación de la morera en Yucatán, México. FAO technical project report. Conkal, Yucatán, Mexico, Instituto Tecnológico Agropecuario #2.
Jayal, M.M. & Kehar, N.D. 1962. A study on the nutritive value of mulberry (Morus indica) tree leaves. Indian Journal of Dairy Science, 15: 21-27.
Jegou, D., Waelput, J.J. & Brunschwig. 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. Benavides, ed. Arboles y arbustos forrajeros en América Central, p. 155-162. Volumen I. Turrialba, Costa Rica, CATIE.
Kamimura, C., Koga, S., Hashimoto, A., Matsuishi, N., Torihama, Y., Nishiguchi, T. & Shinohara, K. 1997. Studies on the factors influencing the mulberry (Morus alba) productivity in fields. Journal of Sericultural Science of Japan, 66(3): 176-191.
Kellogg, E.A. & Juliano, N.D. 1997. The structure and function of RuBisCo and their implications for systematic studies. American Journal of Botany, 84(3): 413-428.
Korn, M. 1996. The dike-pond concept: sustainable agriculture and nutrient recycling in China. Ambio, 25(1): 6-13.
Lara y Lara, P.E., Sanginés G.R. & Dzib, M.R. 1998. Utilización de hojas de morera (Morus alba) en la producción de carne de conejo. In Memorias del IX Congreso Nacional de Investigación y Desarrollo Tecnológico Agropecuario, p. 257. Conkal, Yucatán, Mexico, Instituto Tecnológico Agropecuario #2.
Le Thu Ha, Nguyen Quang Suc, Dinh Van Binh, Le Thi Bien & Preston, T.R. 1996. Replacing concentrates with molasses blocks and protein-rich tree leaves for reproduction and growth of rabbits. Livestock Research for Rural Development, 8(3): 33-37.
Machii, H. 1989. Varietal differences of nitrogen and amino acid contents in mulberry leaves. Acta Sericologica et entomologica (Japan), 1 September 1989, p. 51-61.
Maymone, B., Tiberio, M. & Triulzi, G.A. 1959. Richerche comparative sulla digeribilità delle foglie di gelso nelle larve di Bombyx mori e negli animali superiori. Annali dell'Istituto Sperimentale Zootecnico di Roma, Volume VI.
Mehla, R.K., Patel, R.K. & Tripathi, V.N. 1987. A model for sericulture and milk production. Agricultural Systems, 25: 125-133.
Narayana, H. & Setty, S.V.S. 1977. Studies on the incorporation of mulberry leaves (Morus indica) in layers mash on health, production and egg quality. Indian Journal of Animal Science, 47(4): 212-215.
NRC. 1984. Nutrient requirements of poultry. Washington, DC, National Academy Press, National Research Council. 71 pp.
Ojeda, F., Martí, J., Martínez N. & Lajonchere, G. 1998. Harina de morera: un concentrado tropical. In Memorias del III Taller Internacional Silvopastoril Los árboles y arbustos en la gandería. 25-27 November 1998. Matanzas, Cuba, EEPF, Indio Hatuey.
Oviedo, F.J., Benavides, J.E. & Vallejo, M. 1994. Evaluación bioeconómica de un módulo agroforestal con cabras en el trópico húmedo. In J. Benavides, ed. Arboles y arbustos forrajeros en América Central, p. 601-629 Volumen I. Turrialba, Costa Rica, CATIE.
Prasad, P.E. & Reddy, M.R. 1991. Nutritive value of mulberry (Morus alba) leaves in goats and sheep. Indian Journal of Animal Nutrition, 8(4): 295-296.
Rodríguez, C., Arias, R. & Quiñones, J. 1994. Efecto de la frecuencia de poda y el nivel de fertilización nitrogenada, sobre el rendimiento y calidad de la biomasa de morera (Morus spp.) en el trópico seco de Guatemala. In J. Benavides, ed. Arboles y arbustos forrajeros en América Central, p. 515-529. Turrialba, Costa Rica, CATIE.
Rojas, H. & Benavides, J.E. 1994. Producción de leche de cabras alimentadas con pasto y suplementadas con altos niveles de morera (Morus sp.). In J. Benavides, ed. Arboles y arbustos forrajeros en América Central, p. 305-317. Turrialba, Costa Rica, CATIE.
Shayo, C.M. 1997. Uses, yield and nutritive value of mulberry (Morus alba) trees for ruminants in the semi-arid areas of central Tanzania. Tropical Grasslands, 31(6): 599-604.
Singh, B., Goel, G.C. & Negi, S.S. 1984. Effect of supplementing mulberry (Morus alba) leaves ad libitum to concentrate diets of Angora rabbits on wool production. Journal of Applied Rabbit Research, 7(4): 156-160.
Subba Rao, A., Amrith Kumar, M.N. & Sampath, S.R. 1971. Studies on mulberry (Morus indica) leaf-stalk palatability, chemical composition and nutritive value. Indian Veterinary Journal, 48: 854-857.
Talamucci, P. & Pardini, A. 1993. Possibility of combined utilization of Morus alba and Trifolium subterraneum in Tuscan Maremma (Italy). In Management of Mediterranean shrublands and related forage resource, p. 206-209. REUR Technical Series No. 28. Rome, FAO.
Tikader, A., Roychowdhuri, S., Mishra, A.K. & Das, C. 1993. Foliage yield of different varieties of mulberry (Morus species) grown at two spacings in hill of West Bengal. Indian Journal of Agricultural Sciences, 63(1): 36-37.
Tipton, J. 1994. Relative drought resistance among selected southwestern landscape plants. Journal of Arboriculture, 20(3): 151-155.
Trigueros, R.O. & Villalta, P. 1997. Evaluación del uso de follaje deshidratado de morera (Morus alba) en alimentación de cerdos de la raza Landrace en etapa de engorde. In Resultados de Investigación, p.150-155. El Salvador, CENTA.
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. (thesis, 86 pp)
Velázquez, Claudia M., Gutiérrez, M.A., Arias, R. & Rodríguez, C. 1994. El forraje de Morera (Morus sp.) como suplemento en dietas a base de ensilado de sorgo (Sorghum bicolor x S. sudanense) para novillos. In J. Benavides, ed. Arboles y arbustos forrajeros en América Central, p. 377-392. Turrialba, Costa Rica, CATIE.
Vezzani, V. 1938. La foglie di gelso nell'allimentazione delle vacche da latte. Annali della Sperimentazione agraria Volume XXIX, p. 7-17. Ministerio dell'Agricoltura e delle Foreste, Roma.
Yamashita, T. & Ohsawa, R. 1990. Quantitative investigation on nitrogen metabolism in mulberry leaves. Bulletin of the National Institute of Sericultural and Entomological Science (Japan), March, 1: 27-44.
Zepeda, J. 1991. El árbol de oro. Los mil usos de la morera. Medio Ambiente (Peru), 47: 28-29.