Fodder shrub and tree species in the Highlands of southern Mexico

Fodder shrub and tree species in the Highlands of southern Mexico

ANIMAL FEED SCIENCE AND TECHNOLOGY ELSEVIER Animal Feed Science Technology 68 (1997) 213-223 Fodder shrub and tree species in the Highlands of sou...

749KB Sizes 4 Downloads 17 Views



Animal Feed Science Technology

68 (1997) 213-223

Fodder shrub and tree species in the Highlands of southern Mexico J. Nahed a,*, L. Villafuerte a, D. Grande b, F. Perez-Gil ‘, T. Alemh a, J. Carmona ’ a El Colegio de la Freontera Sur (Ecosur), Diuision de Sistemas de Production. Carretera Panamericana y Periferico Sur s/n. CP 29290. AP. 63. San Crisdbal de Las Casas, Chiapas, Mexico b Uniuersidad Autonoma Metropolitana Iztapalapa, Area de Sistemas de Production Animal. Ac. Michoacrin y La Purisima Col. Vicentina, Iztapalapa, CP 09340, Mgxico, D. F., Mexico ’ Institute National de la Nutricion Saluador Zubircin, Departamento de Nutricibn Animal. Vasco de Quiroga No. 15 Col. y Delegacidn Tlalpan, CP 14000, Mexico, D.F., M&co Accepted

13 March 1997

Abstract The purpose of this investigation was to recognize, to select and to evaluate shrub and tree species with forage potential as a way to promote their systematic use as food for sheep. This research took place in five indigenous communities of Chiapas, Mexico. By means of interviews with producers, a list of 37 species was obtained, of which 14 were selected for evaluation based upon: a) their frequency of use; b) presence of foliage during the drought season (winter); c) local abundance and d) chemical composition and concentration of toxic substances. Among the 14 selected species, six were shrubs and eight were trees. All these species were available all year round. The 14 species showed invasive tendencies and different quantities outside the communities than inside the communities. The values of ecological importance (1.9-4.4) were similar or higher to those found (1.96) in oaks (Quercus spp. ), which is the dominant tree species in the region. The foliage of the 14 species contained crude protein (CP) levels of 7.2-22.3%, gross energy (GE) between 2.9-4.5 k&/g; neutral detergent fiber (NDF) of 21-59%; acid detergent fiber (ADF) of 18-5 1%; tannic acid 0.42-0.69 g/100 g, absence or low content of cyanogenic glucosides and low, moderated or high contents of alkaloids. Based on the distribution patterns, abundance, frequency of use and chemical composition, Rapanea juergensenii, Buddleia sp., Eupatorium semialatum and Ostrya oirginiana, are considered as feasible to be incorporated into

* Corresponding

author. Tel.: 818 83, 818 84; fax: 823 22; e-mail: [email protected];

0377-8401/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PII SO377-8401(97)00052-7

[email protected]


J. Nahed et al./Animal Feed Science Technology 68 (1997) 213-223

the diet of the sheep in the area studied and as a result, it is necessary agronomic evaluations. 0 1997 Elsevier Science B.V. Keywords: Fodder; Shrubs; Trees; Highlands;

to make later diet and

Southern Mexico

1. Introduction During the last years research about agrosylvopastoral systems, as a variant of agroforestry have been internationally important. Within these studies the evaluation of the actual and potential use of the foliage of fodder shrub and tree species in animal nutrition is very important. The proposal is the development of regional agrosylvopastoral systems by mean of productive strategies with the rational use of the natural resources (Benavides, 1994; Pezo, 1991). In various regions of Mexico, the animal production systems are developed based on agrosylvopastoral management. One example is the ovine production system practiced by the Tzotziles Indians of the highlands of Chiapas, Mexico, which is based on extensive grazing. In this system, the producer uses all the available forage fodder resources. As the grazing areas are frequently located far from the place where the animals rest during the night, it is common for the animals to browse in forest areas. On the other hand, to assure the feeding of the animals, the producer uses the foliage of shrub and tree species to supplement the sheep’s diet, principally during the drought (Villafuerte et al., 1993; Parra et al., 1993). Although the producers of the region recognize the fodder potential of woody species, due to the high levels of deforestation, the intensification of land use and the scarcity of fodder during the drought, it is necessary to carry out research into the recognition, evaluation and selection of potential species in the area, with the purpose of studying and planning their incorporation into ovine production, as a part of sustainable development within an integral strategy of the ovine system. Within this context, the objective of this study is the recognition, selection and evaluation of shrub and tree species with fodder potential, as a way to promote their systematic use as feed for the ovine species in the highlands of Chiapas, Mexico.

2. Materials and methods The investigation took place in five representative native localities (1. Bautista Chico; 2. Epalchen; 3. Tzontehuitz; 4. Pozuelos and 5. Yalbante) of Carst-Chamula (Mera, 1989) of the highlands of Chiapas, Mexico (between 92” and 93”O; 16”30’ and 17”N) in an area of 1225 km2. The research was developed from September 1992 to June 1993 and was part of a broader project about the agricultural production carried out by ECOSUR. The average altitude is 2300 m a.s.l., the region’s climate is temperate, subhumid, C (w,) (w) in Koeppen’s classification, modified by Garcia (1988), with an average annual temperature of 1l- 16°C and average annual rainfall of 1 lOO- 1300 mm. The woody shrub and tree species commonly used to feed the ovines during the drought season were identified based on interviews with the producers and by field observations. The search for alternatives to the sheep’s feed was initiated by exploring

J. Nahed et al./Animal

Feed Science Technology 68 (1997) 213-223


the producer’s knowledge. When selecting the woody species with higher fodder potential, the following approaches were taken into consideration: a) present use by the shepherds from the zone, b) fodder availability in the winter season, c) local abundance and d) chemical composition with acceptable nutritional content and low concentration of toxic substances. Because our objective was to find alternatives for the winter shortage of fodder, the Table 1 Multipurpose

fodder plants used in sheep feeding in Bautista Chico, Chiapas, Mexico

Common name in Tzotzil

Scientific name

Growth pattern


Tilil Ch’a te’ Con con Pits’ots’ Ic’al uinic Mes te’ Pomos Cam itaj te’ Ts’utuj te’ Tzelopat Tulan Pochij anal C’oxox te’ C’os Chikinim, Biktajanal Culchish K’ail Vervesh Acanjovel Canquis Yisinbe Mata’s Saju’ Tzemeni Pajal bomol Ch’upak Jove1 Macom Ajte’ C’ak’et te’ Yanalmail Yanalchenek C’ajben Yanalchomtik Chixte’ Isbom Tsop Limoncillo

Rapanea juergensenii Eupatorium semialatum Cavendishia guatemalensis Monnina xalapensis Garrya laurifolia Baccharis vaccinioides Holodiscus argenteus Verbesina perymenioides Ostrya virginiana Buddleia sp. Quercus rugosa Quercus crassifolia Cleyera theaeoides Fuchsia paniculata Quercus laurina Smilax bona-nox Montanoa leucantha Viola aff. humilis Cynodon dactylon Trifolium repens Cyperus sp. Videns bicolor Simsia sp. Commelina coelestis Trtfolium sp. Prochnianthes viridescens Mulhembergia sp. Rubus sp. Casimiroa sapota Cletra suaveolens Cucurbita sp. Phaseolus sp. .%a mays (straw) Zea mays (green leaves) Acacia pennatula Comus excelsa Viburnum jucundum Dalea leporina

Tree Shrub Shrub Shrub Tree Shrub Shrub Tree Tree Tree Tree Tree Tree Shrub Tree Herb Tree Herb Grass Herb Herb Herb Herb Herb Herb Herb Grass Herb Tree Tree Herb Herb Herb Herb

1.2, 3.4 1.2, 5 1.4 1, 5 1,273 1.2.3 1,2 1, 2 1

Use code: 1 = fodder; 2 = firewood; 7 = detergent; 8 = green manure.

3 = traditional



Tree Shrub Herb 4 = ornamental;

1, 2 1, 2 1, 2 1 1, 2.4 1, 2 1 1, 3 1, 3 1 1 1 1 1 1 1, 3 1, 7 1 I, 3 1, 6 1, 2

1 1 1, 8 1 1 1 1 1 5 = tint; lj = human



J. Nahed et al./Animal Feed Science Technology 68 (1997) 213-223

selection was focused only on those shrub and tree species that continue to have foliage during the drought season, when there is not enough pasture. This part of the investigation, was realized with a sample of 15 shepherds from the Bautista Chico community, a district of San Juan Chamula, and was used to generate a reference frame to guide the compilation of information from the shepherds of other selected communities. Samples were collected for taxonomic identification and later they were incorporated into the ECOSUR herbarium. The vegetation was sampled by the Point-Centered Quarter Method (Mueller-Dombois and Ellenberg, 1974). Later, the relative abundance of the species was determined by the means of the values of ecological importance (Mueller-Dombois and Ellenberg, 1974). To discover their local availability, the patterns of distribution of the species were identified according to the detection of no-aleatority method (Kershaw and Kenneth, 1973). At the same time, surveys and direct observations were realized to find out the frequency of the producers-preferred species. Enough biological material was collected for the chemical analyses that included: dry matter (DM), crude protein (CP) according to the established methods by the AOAC (1990); gross energy (GE) (calorimetric adiabatic bomb); neutral detergent fiber (NDF) and acid detergent fiber (ADF) with the Van Soest et al. (1991) method. The presence of alkaloids (ALK), cyanogenic glucosides (CG) and tannic acid (TA) were evaluated by the technique of Dominguez (1979). 3. Results 3.1. Identification and selection of species Initially, a list of 37 species used in the sheep’s diet was obtained (Table 1). In Table 2, the 14 species of shrubs or trees considered by the peasants as good fodder during the drought season are presented. Table 2 Most common shrub and tree species used as fodder during drought season and distribution the Highlands of Chiapas, Mexico Common name in Tzotzil


Scientific name


Cam itaj te’ C’os C’oxox te’ Ch’a te’ Con con Ic’al uinic Mes te’ Pits‘ots’ Pochij anal Pomos Tilil Ts’utuj te’ Tzelopat Tulan

Compositae Onagraceae Theaceae Compositae Ericaceae Garryaceae Compositae Polygalaceae Fagaceae Rosaceae Myrsinaceae Betulaceae Loganiaceae Fagaceae

Verbesina perymenioides Fuchsia paniculata Cleyera theaeoides Eupatorium semialatum Cauendishia guatemalensis Garrya laurifolia Baccharis vaccinioides Monnina xalapensis Quercus crassifolia Holodiscus argenteus Rapanea juergensenii Ostrya virginiana Buddleia sp. Quercus rugosa

C(1,2,3) -

in communities


type and communitie?

C&2,3) C(1,2,3,5) C( 1.3) C(1,2,5);A(3) C(1.2M.5) C(1 ,2 I3 94 35) C(1 92 93 34 ,5) C(1,2,3,4,5) C&3,5) C(1,3) C(1 ,2 73 ,4 35) C(1,2,3,4,5)

“A = aleatory distribution and C = contagious distribution; numbers within parenthesis are the communities follows: 1 = Bautista Chico; 2 = Epalchen; 3 = Tzontehuitz; 4 = Pozuelos and 5 = Yalbante.


J. Nahed et al./Animul Table 3 5yRelative


Feed Science Technology 68 (1997) 213-223

of shrub and tree species at the localities

Rapanea juergensenii IV = L2 L3 L4 L5

2.1 Ll

0 L2

2 L3



2.6 L5

= N



Eupatorium semialatum IV = L2 L3 L4 L5

3.66 Ll

2 L2 * N N

1.91 L3

0 L4

2.16 L5

* N

L2 L3 L4 L5

0 Ll N N N N


L2 L3 L4 L5

1 Ll N * * *

0 L2 N N N

0 L3


0 L4

0 L5

L2 L3 L4 L5

2.6 Ll * N * *


L2 L3 L4 L5

2 Ll N N N N

1.2 L3

3 L4

1.35 L5

*I N * N







1.87 Ll * N * N

3.16 L2

2.08 L3

3.75 L4

N * N



0 L2

1.91 L3

0 L4

* N N

* *

2.3 L2

1.8 L3

N * N


3.5 L2

1.16 L3

N ’ N



0 L2

1 L3

0 L4




1.66 L5

1 Ll N * N N

0 L5


Garrya laurifolia

1.9 L2 N N N

1.6 L3


3.4 L4

2.4 L5

1 L2


Quercus 1.5 L3

0 L4

0 L5

* *

IV = L2 L3 L4 L5

* N N

IV= L2 L3 L4 L5


Cleyera theaeoides IV=

IV= L2 L3 L4 L5

Verbesina perymenioides IV=

3.25 L2

Ostrya cirginiana

Monnina xalapensis IV=

IV= L2 L3 L4 L5

Fuchsia paniculata IV=

1.25 Ll

Holodiscus argenteus

* N * *

IV= L2 L3 L4

* N *

studied (n = 6 samples or transects)

Buddleia sp.

* N N


1.5 LI N N N *

0 L4

4.2 L5

4.4 L4

2.33 L5


sp. 3.12 Ll N N N N


Caaendishia guatemalensis







0 L4


0 L5

IV= L2 L3 L4 L5

1 Ll N N N N

0 L5

J. Nahed et al./Animal Feed Science Technology 68 (1997) 213-223

218 Table 3 (continued)

Baccharis uaccinioides IV= L2 L3 L4 L5

1 Ll * N N N

3.41 L2

0 L3

2.66 L4

* N *



2.5 L5

L = Location; Ll = Bautista Chico; L2 = Epalchen; L3 = Tzontehuitz; N = Not significant; * = (P < 0.05); N = mean of importance values.

3.2. Distribution

and quantities

L4 = Pozuelos

and L5 = Yalbante.

of the species

Table 2 also shows the distribution and ecological relevance of the selected species. It shows that the 14 selected species’s present distribution tendencies in specific groups, although scattered (contagious distribution). It also shows variations in the abundance of the species between localities and the differences between species within the same location. In Table 3, the relative quantity of the species is shown by the values of ecological importance in each vegetative association studied. The average importance values (IV) calculated for the majority of the species

Table 4 Chemical


of selected shrub and tree leaves in the highlands

Scientific name Verbesina perymenioides Fuchsia paniculata Cleyera theaeoides Eupatorium semialatum Cauendishia guatemalensis Garrya laurifolia Baccharis vaccinioides Monnina xalapensis Quercus crassifolia Holodiscus argenteus Rapanea juergensenii Ostrya uirginiana Buadleia sp. Quercus rugosa

of Chiapas,

Mexico (n = 3)






Tannic acid







27.8 24.9 37.1 24.8 33.6 38.1 37.0 21.3 49.0 39.6 27.9 30.8 35.8 53.0

11.8 9.4 17.7 9.2 5.0 7.2 13.0 10.0 7.4 9.3 13.1 22.3 10.1 9.1

3.8 3.3 3.7 4.2 3.5 4.3 4.1 4.1 3.9 4.1 4.5 3.8 2.9 4.1

30 25 28 31 54 39 26 21 59 34 39 54 33 53

28 26 23 29 47 30 21 18 52 18 33 51 25 31

0.475 0.699 0.495 0.582 0.440 0.586 0.437 0.499 0.427 0.671 0.519 0.517 0.648 0.414



Abund. Mod. scam. scam. Neg. Mod. Abund. Abund. Mod. Mod. Neg. scam. Mod. Scam



Neg. Neg. Neg.

Neg. Neg. Neg. Neg. Neg. Neg. Neg. Neg.

DM = Dry matter; CP = Crude protein; GE = Gross energy; NDF = Neutral detergent fiber; ADF = Acid detergent fiber; Alk = Alkaloids; CG = Cyanogenic glucosides. ‘Qualitative analysis. Abund. = Abundant; Mod. = Moderated: Scam. = Scarce; Neg. = Negative.

J. Nahed et al. /Animal Feed Science

Technology68 (1997) 213-223


(1.9-4.4) are similar or superior to the values (1.96) of oak (Quercus spp.1, the dominant species in the natural vegetation of the zone. Because only the presence of the species is considered and not the biomass, the IV obtained showed individual abundance and ubiquitous presence in the vegetative communities studied.

3.3. Chemical composition

of the foliage

Table 4 shows the results of the chemical analysis of the selected forage species. In general, the species have crude protein content from medium to high (7.4-22.3%). Ostrya uirginiana shows almost double the value of the other species. The shrubs and tree species have high contents of gross energy and moderate levels of fractions of fiber. Rupanea juergensenii, Buddleia sp., Euputorium semialutum and 0. uirginiana have potential as feed when compared with the naturalized fodder grasses of the region which have average amounts of 10% (dry matter basis) of crude protein in vegetative stage (Urquijo et al., 1991). The foliages have tannic acid contents of 0.42-0.69 g/100 g, low, moderate or high contents of alkaloids, and an absence or low levels of cyanogenic glucosides.

3.4. Intensity and potential


The selected species were identified based on the peasants’ knowledge, and for this reason the frequency in which the species exist in the region is shown in Table 5, indicating their frequency of use as part of the sheep’s diet. Verbesinu perymenioides,

Table 5 Frequency

of use (‘700)of shrub and tree species in the communities

Scientific name ?Z= Verbesina perynenioides Fuchsia paniculata Cleyera theaeoides Eupatorium semialatum Cavendishia guatemalensis Garrya laurifolia Baccharis uaccinioides Monnina xalapensis Quercus crassifolia or Q. rugosa Holodiscus argenteus Rapanea juergensenii Ostrya IGrginiana Buddleia sp.

Communities” 1 2 11 10 72 _ 45 9 9 18 _ 45 21 18 18 18 63

’1 = Bautista Chico: 2 = Epalchen; 3 = Tzontehuitz; n = number of producers interviewed.

_ _ _ _ _ _ 20 _ _ 10 _

of Chiapas,

3 12


4 II

66 41 58 25 25 58 50 15 58 25 58 8 83

4 = Pozuelos and 5 = Yalbante.


5 15

63 _

20 20 _




20 40 20

36 _






J. Nahed et al./Animal Feed Science Technology 68 (1997) 213-223

Monnina xalapensis and Buddleia sp. are important species with high percentages of

use in various communities. 4. Discussion

The existence of different abundances of the species between and within localities, and at the same time their distribution tendencies without any spatial arrangement, has to be explained by the absence of management and by the characteristics of the reproductive structures. The majority of the species produce small fruits with hairs, bristles or scales, which facilitate their dispersion by wind or by attaching themselves to peasants’ clothing or to animal fur. The reproduction of these species seems to be based on the abundant production of seeds for easy dispersion and with a fast vegetative development. On the other hand, there is a relationship between the ovine population and its effects on the grassland condition, and this could explain the different use intensities of the studied species; in this sense, Epalchen was the community where the use of shrub and tree species was less important. This could be explained by the small ovine population, and for this reason the grasslands are in a better condition than the other communities studied. This situation emphasizes the need to investigate appropriate management methods that allow a higher forage production, and that will guarantee availability, principally during a period of shortage (Ikwegby et al., 1995). The use of foliage is now aleatory because the sheep are permitted to graze within the community, where the presence of very small parcels mean severe restrictions on the use of the resources and which also limits the freedom of the animals to select their own feed (Nahed and Parra, 1984). From the nutritional aspect, the fact that some species present an acceptable quantity of crude protein, moderate levels of fractions of fiber, high gross energy, low contents of tannic acid and alkaloids, an absence of cyanogenic glucosides, and are attractive to the sheep, makes the use of these species promising (Febles et al., 1995). The breeding of sheep is very important in the strategies for the use of the Tzotziles’s natural resources in the Highlands of Chiapas, from the point of view of the ecological nutriment flow, circulation of material between the production systems, the rotation in the use of the soil and the fertilization of the agricultural crops with manure, (especially in small parcels cultivated in an intensive way with vegetables), as well as from the economic (Bayer, 1986) (monetary and no-monetary profits through the sale of animals and their wool) and social aspects (i.e., the use of wool in the manufacture of their traditional costumes and the production of crafts to be sold) (Nahed and Parra, 1984). The results obtained suggest that the systematic use of the shrub and tree species as a complement in the difficult periods could contribute considerably to the solution of the nourishment problem of sheep in the area (Ikwegby et al., 1995). The possibility of this contribution increases if it is taken into consideration that the actual sheep production does not fully depend on the land’s grazing capacity, but is combined with agricultural products and the weeds of the cornfields (Nahed and Parra, 1984). The aim to systematically use the foliage of shrubs and trees as fodder is coincidentally related to the strategies of multiple use of the resources, which is the basis of the

J. Nahed et al./Animal Feed Science Technology 68 (1997) 213-223


agricultural production in the studied zone. As a consequence, these forages could provide nutrients to meet the physical and physiological necessities of the sheep, and animal production could be improved. Furthermore, it could help to slow the rapid deterioration of the grassland areas (Parra et al., 1993; Botero, 1989). These species also contribute towards the satisfaction of the basic necessities of the families, such as firewood and the construction of hedges (National Academy of Sciences, 1980). This reinforces their importance in the multiple-use strategies. It is appropriate to begin agronomic studies that permit the identification of improved management as well as biological assays to evaluate the animals’ response to the foliage of these species. It is important to know their distribution and abundance in natural conditions because this facilitates the identification of the areas in which they are abundant, an important aspect in understanding the appropriate conditions for their development and in related studies. The adoption of any alternatives to the shortage of forage in the studied region depends upon several factors, not only those of a technical nature but also sociocultural: a) the priority that each problem has to the development of the families; b)the integration of the proposed strategies to the use of the natural resources; c) the risk implied; d) the knowledge and the required abilities to use them; and e) the availability of the basic materials to implement it. It is also necessary to look for all other relevant aspects involved in the study in order to determine the adoption or not of the proposed sheep management techniques: training, technical assistance, organization, etc. It is desired to improve the productivity of the used work in the sheep’s breeding within the integrated handling concept, conservation of natural resources and improvement of the peasants standard of living (Wilken, 1987). This objective to design ecologically and economically sustainable agricultural systems is shared by a similar project at ECOSUR.

5. Conclusions The development of ovine production in the Highlands of Chiapas, Mexico, is possible given the people’s knowledge of the forage potential of several tree and shrub species. This potential is a consequence of their actual use, their natural availability, their production of foliage during the drought season, their acceptable qualities and the sheep’s preference. In general, the shrub and tree species studied showed acceptable contents of crude protein, fractions of fiber and gross energy, low contents of tannic acid, an absence or low content of cyanogenic glucosides, and a low, moderate or high presence of alkaloids. Based on the distribution patterns, abundance, frequency of use and chemical composition of the species studied, it is considered that R. juergensenii, Buddleia sp., E. semialatum and 0. virginiana present favorable characteristics for their incorporation into the region’s sheep’s feeding. It is necessary to realize studies about animal production and grassland improvement in relation to confined or grazing animals, in order to evaluate the foliage use of the


J. Nahed et al/Animal

Feed Science Technology 68 (1997) 213-223

promising species, and to make the maximum use of the other fodder resources available to the producer. On the other hand, it is necessary to develop agronomic studies to evaluate the establishment of appropriate management strategies according to the producer’s possibilities. The improvement of ovine production needs the proposed alternatives to be adapted to the economic and social conditions relevant to the region. Particularly it has to continue the search for alternatives that will increase the efficiency of labor and at the same time encourage a favorable form of organization that will improve the peasants’ way of life.


The authors are grateful to Ruth Pealing, participant in the CONACYT-BRITISH COUNCIL Exchange Programme for helping in the translation and revision of the manuscript. The authors are also thankful to Susana Ochoa, Nepthali Ramirez, Roberto Parra, Salvador Meza, Lorena Soto, Hector Plascencia, Blanca Diaz and to the cooperant producers of the Highlands of Chiapas for helping in the realization of this study. We also wish to thank to the National Council of Science and Technology of Mexico (CONACYT) and to Rockefeller Foundation for their financial support.

References AOAC, 1990. Official Methods of Analysis of the Association of Official Analytical Chemists, 15th edn. Association of Official Analytical Chemists, Washington, DC. Bayer, W., 1986. Traditional small ruminant production in the subhumid zone of Nigeria. In: von Kaufmann, R., Chater, S., Blench, R. (Eds.), Livestock Systems Research in Nigeria’s Subhumid Zone. Proceedings of the Second ILCA/NAPRI Symposium held in Kaduna, Nigeria, Oct. 29-Nov. 2. ILCA, Addis Ababa, Ethiopia, pp. 141-166. Benavides, J.E., 1994. La investigaci6n en arboles forrajeros. Arboles y Arbustos Forrajeros en America Central, vol. 1, Centro Agron6mico Tropical de Investigaci6n y Ensehanza. Turrialba, Costa Rica, pp. 3-28. Botero, R., 1989. Los &rboles forrajeros coma fuente de proteina para la producci6n animal en el trbpico. Sistemas de Alimentacion Animal en el Tr6pico Basados en Caiia de Azhcar. Colecci6n GEPLACEA/PNUD, Serie Divulgaci&, Grupo de Paises Latinoamericanos y de1 Caribe Exportadores de Azucar, Mexico, D.F., pp. 155-176. Dominguez, X.A., 1979. Metodos de Investigacidn Fitoquimica. LIMUSA, Mexico, 110 pp. Febles, G., Ruiz, T.E., Simon, L., 1995. Consideraciones acerca de la integraci6n de 10s sistemas silvopastoriles a la ganaderia tropical y subtropical. Memoria de1 Seminario Cientifico Intemacional, 30th Aniversari0 de1 Instituto de Ciencia Animal, 25-27 Octubre 1995. Instituto de Ciencia Animal, La Habana, Cuba, pp. 55-63. Garcia, E., 1988. Modificaciones al sistema de clasificacion climatica de Koeppen, Universidad National Aut6noma de Mexico, Mexico, 70 pp. Ikwegby, O.A., Tarawali, G., Rege, J.E.O., 1995. Effects of fodder banks on growth and survival of West African Dwarf goats under village conditions in subhumid Nigeria. Small Rumin. Res. 17, 101-109. Kershaw, B., Kenneth, A., 1973. In: Arnold, Edward (Ed.), Quantitative and Dynamic Plant Ecology, 2nd edn. 308 pp.

J. Nahed et al./Animal

Feed Science Technology 68 (1997) 213-223


Mera, O.L.M., 1989. Condiciones naturales para la production. In: Parra, M.R. (Ed.), El Subdesarrollo Agricola en Los Altos de Chiapas. Centro de Investigaciones Ecol6gicas de1 Sureste y Universidad Aut6noma de Chiapas, San Crist6bal de Las Casas, Chiapas, Mexico. pp. 31-82. Mueller-Dombois. D., Ellenberg, H., 1974. Aims and Methods of Vegetation Ecology,

Wiley, New York, 547

PPNahed, J., Parra, M.R., 1984. Ovinocultura en Los Altos de Chiapas: Un sistema traditional. Revista Mexicana de Producci6n Animal (Mexico) 16, 26-41. National Academy of Sciences, 1980. Shrub and Tree Species for Energy Production, vol. I. National Academy Press, Washington, DC. Parra, M.R., Nahed, J., Soto, M.L., Garcia, M.C., Garcia, L.E., 1993. El Sistema ovino Tzotzil de Chiapas. Din&mica de1 manejo integral. Agrociencia (Mexico), Serie Recursos Naturales Renovables 3 (21, 79-89. Pezo, D.A., 1991. La producci6n ganadera en un context0 agroforestal. El Chasqui. 25, 1-2. Urquijo, V.G., Nahed, J., Quintana, P.F., 1991. Productividad de pastizales naturalizados bajo exclusidn y apacentados por ovinos en Los Altos de Chiapas. Universidad Autdnoma de Chiapas/-Gobierno de1 Estado de Chiapas y Asociaci6n Mexicana de Ttcnicos Especialistas en Ovinos. Memorias del 4th Congreso National de Producci6n Ovina. San Cristdbal de las Casas, Chiapas, Mexico, pp. 45-47. Van Soest, P.J., Robertson, J.B., Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber and nonstarch polysaccharides in relation to animal nutrition, J. Dairy Sci. 74 (101, 3583-3597. Villafuerte, L., Nahed, J., Aleman, T., Perez-Gil, F., Grande, D., SanginCs. L., 1993. DOS especies vegetales arbustivas con potential forrajero en Los Altos de Chiapas, Mexico. Memorias de1 Segundo Seminario Centroamericano y de1 Caribe sobre Agroforesteria con Rumiantes Menores. CATIE, San Jose, Costa Rica. pp. 1-8. Wilken, G.C., 1987. Good Farmers. Traditional Agricultural Resource Management in Mexico and Central America. Univ. of California Press, Los Angeles.