REVIEW

Agro-ecological principles in Cuban technologies with legumes for animal production

Principios agroecológicos en tecnologías cubanas con leguminosas para la producción animal

J. Alonso

ABSTRACT

Different ecological principles are analyzed, which should be included on the management and exploitation of Cuban cattle agricultural systems. These systems are characterized by the use of grasses and forages as main basis of their feeding systems. It is important the use of shrubs and creeping legumes in technologies that favor biological diversity, soil restoration and agricultural-animal husbandry integration, as strategy for the development of a more profitable and ecologically stable livestock activity. Finally, an evaluation is carried out to the need of developing animal production systems in tropical areas that visualize the approach to natural systems as a real and practical alternative for persistence, sustainability and environmental regulation of animal husbandry agro-ecosystems.

Key words: agro-ecology, grazing systems, animal production.

RESUMEN

Se analizan algunos principios ecológicos que se deben incorporar en el manejo y explotación de los agroecosistemas ganaderos cubanos, caracterizados por la utilización de los pastos y forrajes como base fundamental en sus sistemas de alimentación. Se destaca la utilización de leguminosas, rastreras y arbustivas,  en tecnologías que favorecen la diversidad biológica, la restauración de suelo y la integración agricultura-ganadería, como estrategia para el desarrollo de una actividad pecuaria más rentable y estable ecológicamente. Se valora la necesidad de desarrollar sistemas de producción animal cercanos a los sistemas naturales, como alternativa práctica y real para la persistencia, sostenibilidad y regulación ambiental de los agroecosistemas ganaderos en el trópico.

Palabras clave: agroecología, sistemas de pastoreo, producción animal.

INTRODUCTION

Human activity is responsible for 90 % of climatic changes occurring on the planet. In the last decade, the rate of deforestation, at world level, reached 13 million of ha year^-1 (FAO 2012), with local effects such as soil degradation and loss of their productivity. The transformation of large forested lands into animal husbandry areas, through deforestation, contributes to a quarter of greenhouse gas emissions, biodiversity loss in natural forests and imbalance of other soil ecosystems.

Currently, human beings have changed, through conventional agriculture, the environmental structure in large areas, replacing the diversity of nature with several cultivated plants and domestic animals (Peters et al. 2010). This serious process has favored the development of livestock production systems that are based on the use of monoculture, the application of toxic and chemical fertilizers, and irrigation water that fail to increase efficiently the production and productivity, mainly due to the lack of budget for purchasing these inputs and to the ignorance of the existing interactions between animal and plant species with agro-ecosystem.

Inevitably, natural resources in tropical regions, necessary to encourage the agricultural development, suffer from an accelerated deterioration that endangers the solution for vital needs of future generations, with the known risks to ecological, social, political and economic stability in many countries, mainly due to management practices used by them. According to Molina and Uribe (2005), tropical animal husbandry faces serious challenges due to the prevailing production model, characterized by large extensions and little or no diversity of species.

Despite these questions, Ibrahim et al. (2006) reported that animal husbandry is a type of subsistence and alleviation of poverty in many developing countries. The first characteristic of these production systems, mainly from medium to small scale, is that different strategies are implemented on them, which allow them to resist the problems of market and natural disasters since, from an environmental point of view, some studies show that it is feasible to develop animal husbandry, conserving the environment through the use of integrated technologies (Murgueitio 2003, Funes-Monzote et al. 2008).

This review analyzes some of the potentialities that can be obtained in beef and milk production with the implementation of agro-ecological technologies, which visualize the improvement of livestock agro-ecosystems through the use of legumes and the adaptation of agricultural practices that consider integration as an essential tool for animal production in tropical areas.

CONCEPTUALIZATION AND DIMENSION OF AGRO-ECOLOGY IN CATTLE AGRICULTURAL SYSTEMS

It is obvious that for beef and milk production based on grasses and forages, the most important approach, from the agronomic, biological, economical and social point of view, is the one that achieves the balanced combination of all the components that intervene in the “soil-plant- animal-man” complex (agro- ecosystem), in which influence and relate all the factors that affect the production, use, stability and permanence of different components.

Altieri and Nicholls (2004) noted that an agro-ecosystem can be defined, to any scale, by the interactions between people, natural resources and food production in an area or specific field, making difficult to define its exacts limits. This definition has to do directly with the agro-ecology concepts, as it focuses in the ecological relations that take place on the agricultural and livestock systems, with the purpose of clarifying the structure, functions and dynamics of these relations.

It is obvious that the design of agro-ecological systems can not be based on rules, but on principles. It must take into account the existing realities, the farmer knowledge and their aspirations. Besides of provide other economic, ecological and productive considerations (García Trujillo 1996). Among these principles it stands:

- Biological diversity: rotations, polycrops, wooded areas and animals, among others.

- Protection of soils and increase of their fertility by naturals means:  minimum culture, contour lines, munching, replace crops, green manure, organic matter, amendments, rotations, among other.

- Increase of nutrients recycling: use of agricultural wastes for animal feeding, manure as fertilizer, crop rotation, use of plants that extract nutrients from deeper soil layers, use of green manure that mobilize nutrients, activation of soil  biology.

- Increase of the nitrogen biological fixation: use of legumes, green manures, nitrogen fixing trees, activation of soil life.

- Promotion of techniques that conserve soil moisture: munching, minimum culture, organic matter, protective crops, replace crop, among others.

- Implementation of integration systems: use of biological diversity, efficient use of land, use of multi- layer, allelopathic effects and suppressive of undesirable plants.

The application and use of these agro- ecological principles in the animal production systems in tropical areas show the necessity to develop technologies that increase the interaction between each of the system components, with multidisciplinary character and decisive participation of the experience and local knowledge of the producers. The knowledge of these characteristics indicates the simplicity of what should be made and the complexity with which the technologies should be implemented for the production system.

AGRO-ECOLOGICAL PRINCIPLES IN TECHNOLOGIES WITH LEGUMES

The biodiversity in animal husbandry agro-ecosystems can be as varied as the different crops, weeds, arthropods or microorganisms, according to geographical, climatic, edaphic localities and socioeconomic factors (Navarro et al. 2012). The interactions between the various biotic components can also being of multiple natures. Some of these interactions can be used to induce positive and direct effects on the biological control of specific of crops, regeneration and increase of soil fertility and its conservation. The exploitation of these interactions in real situations involves the agro-ecosystem design and management, and requires an understanding of the numerous relations between soils, microorganisms, plants, insects, herbivores and natural enemies.

Studies carried out by Alonso et al. (2007) showed significant increase in the species richness and the biological diversity index of Shannon, as a leucaena-guinea grass silvopastoral system was developed. They also verified increase in the macrofauna of the soil, birds and insects associated to the system. These results are also related with the difference that is obtained with the silvopastoral systems in the number of plant strata and with the presence of a half stratum of leucaena shrubs that, together with the exploitation time of the system, led to increased the total productivity of the system, of plant diversity and, therefore, of the number of associated species.    

Valenciaga et al. (2010), when studying cattle agro-ecosystems with the use of a silvopastoral system with leucaena-guinea grass showed the system capacity as insects and arachnids reservoir. According to their alimentary habits, these authors classified the arthropods in phytophagous and bio-regulators. It was gather the majority in the Insecta class, and the rest, in the Arachnida. The Hemiptera order, with its sub-orders Homoptera and Hemiptera, had a good representation of phytophagous, while the Coleoptera order grouped the known    crysomelids, responsible for the holes in the leaves, and the Chilocorus cacti, bioregulator insect belonging to the Coccinelidae family. This last is an excellent predator of aphids and psyllids, very frequent in leucaena-guinea grass silvopastoral systems.

The abundance and proportion of bio-regulators depend intimately on the abundance and proportion of the phytophagous and, at the same time, on the type and the architecture of the plants in the area. This situation is justified by the ecological theories cited by Altieri et al. (2011). The hypothesis of the natural enemies states that in the diversified agro-ecosystems there is higher variety and quantity of feeding available sources, better microhabitat conditions, changes in the chemical signs affecting the location of pests and increase in the stability of the dynamics of predator-prey and parasitoids-host populations. These factors contribute to the improvement of the reproduction success, survival and efficacy of the natural enemies.

The beneficial interactions that could show in the implementation of agro-ecology systems with the presence of legumes trees and shrubs in grazing systems for meat and milk production, are also reflected in the increase of nutrient recycling by the return to the soil of leaves, fruits, branches, feces and urine, which is due, mainly, to the increase of the soil biological activity. Alonso (2004) showed that the soil macrofauna, in a leucaena-guinea grass silvopastoral system, was stabilized in the time with annelids prevalence which with their activity favored the soil aeration and accelerated the litter decomposition.

According to Lok (2006), trees in silvopastoral systems have ecological functions on soil protection, reduce the direct effects of the sun, water and wind. They can also modify the soil physical characteristics, when improving their structural stability by the addition of litter, roots and stems (Murovhi et al. 2012); besides of increasing the organic matter values, the capacity of cationic interchange and N, P and K  availability (Martínez 2013).

Other studies show better use of the soil nutrients and higher grass availability, when nutrients were associated to tree species, due to the improvement of soil fertility and shade conditions that are created in the agro-ecosystem (Hernández and Sánchez 2006).The effect of these systems on the soil fertility not only be expected on superficial layers but it also occur in deeper laters, as the exploitation time of the system increases, a phenomenon found when studying a silvopastoral system with  Acacia mangium and Brachiaria decumbens.

The use of mixed agro-ecosystems, with more complex interaction levels, could increase the land use and animal production, since they are more ecologically stables and their practice can recover and increase soil productivity, stabilize a sustainable agriculture and generate multiple environmental services. Naranjo et al. (2012) concluded that the intensive silvopastoral systems with tree legumes are technologies that can contributes to the mitigation of climatic change because they have, for their productive capacity( plant and animal), a natural capital that allows to reach a positive balance of greenhouse gas effect.

These systems have, in principle, a macrobiotic effect of great importance for the environment, in the soil management and conservation, environment and basins protection, so they guarantee higher sustainability of agricultural and cattle productive process by means of obtaining forages, animal protein and forest product.

The conversion of a specialized system for the livestock production to another of agricultural- animal husbandry integration, at farm level, was study object during ten years by Funes-Monzote et al. (2008). These authors demonstrated that the matter is not if high or low inputs are used, or if the production is specialized or diversified, but the specific characteristics of the production systems and the way in which the inputs and agro-diversity are managed.

The farms, integrated in 25 and 50% of the area with agricultural crops, were highlighted by having higher diversity of the production and therefore, higher variation of the agro-diversity, in time and space (table 1). In low inputs conditions and high uncertainty in which these farms operate, the high diversity greatly contributes to reduce danger and to elevate productivity. The internal and external resources were used with higher efficiency in the integrated farms and these, in turn, were more efficient in the use of energy, when reducing the energy costs of protein production.

PRODUCTIVE RESULTS WITH CUBAN TECHNOLOGIES UNDER AGRO-ECOLOGICAL PRINCIPLES

There are many benefits that the agro-ecological principles can contribute in technologies for cattle exploitation. The positive effect of the grasses and legumes association on the dry matter yield and the availability of the edible dry biomass (Ruiz et al. 2015) explains the best bio-economical perform of the exploited herds in agro-ecological systems.

The impacts of the intensive systems, mainly in soil component and therefore in the biomass production, showed the need to raise the participation level of legumes in the grazing area. In this context Iglesia and Martín (2011) showed, that the renovation and introduction of appropriate grasses, and adapted to the local edaphoclimatic conditions, join to the strategic incorporation of trees and shrubs plants in  grazing areas, could be a technological alternative that would contribute to improve cattle production, reducing the negative impact in the ecosystems where it is developed. 

However, the persistence of the legume component in grazing systems has always been a question since its useful life generally does not exceed two years of exploitation when they are mainly used in monoculture. This technological problem motivated the most efficient use of the biological diversity of this family in grazing systems, facilitating the development of technologies where the association of grasses with multiple legumes mixtures is used.

Papers developed to deep in the performance of associations of creeping grasses – legumes under grazing show us that the low plants population and of rooted points per square meter are the causes of the low stability of biomass production of these systems (Ruiz et al. 2005). As commonly happens in the associated grasslands, the legume only has as  anchor point the mother plant, while branches grow over the grass but without being able to take root. The papers related with grassland establishment and exploitation should be guided to achieve a great number of plants and rooted points per area.

The association of herbaceous or shrubs legumes with pastures, as an option to introduce agro- ecology principles and to intensify the land use in cattle areas, has economical advantages because of the  animal production increase. Regarding to their use in systems for replacement female feeding, Iglesias et al. (2006) showed that during the dry season it is possible to reach individual gains higher than 500 g/animal/d in growing yearling heifer that grazed andropogon associations with centrosema, rotationally, with an stocking rate of two animals/ha, which did not differ of that obtained in common guinea, fertilized with200-30-50 of NPK/ha/year.

Mejías et al. (2000) demonstrated the advantage of an appropriate feeding in the post weaning period in calves that grazed an association of pangola (Digitaria decumbens) and stylo (Stylosanthes guyanensis).These authors obtained gains in this initial phase of 478 g/animal/d, that allowed to reach to the yearling stage with more than 200 kg of live weight and begin grazing in a tree- grass association.

These results facilitated to design a technology, in which the association of grasses and creeping or shrubs legumes were used in 100% of the area for rearing replacement females, and not as protein bank, which generates and increase the agro- ecological principles in the whole system .The studies showed that the dependence of external inputs in these systems was minimal, since the grazing areas were not fertilized and irrigated; while the animals neither received any supplementation during the dry period (Iglesias 2003). The high grassland availability, besides the contribution provided by herbaceous legumes and leucaena by browsing and pruning, allowed the animals covered their nutritional requirements and to obtain desired gains for the yearling female category (table 3).

The use of agro- ecological principles in technologies for milk production were beginners in tropical regions, with the use of legume component as protein source in the feeding of animals that allowed to reach individual productions close to  10 L/cow/d. Nevertheless, at the end of 90s in last century, these technologies showed the possibility of increasing the total milk production per effect of raising the total stocking rate, due to the increase in the biomass quantity and quality and its effect on the milking cows percentage.

Other papers show that when comparing systems of grasses monoculture, with a silvopastoral system of grasses and tree legumes, significant improvements were achieved in all the productive indicators of the dairy herd (table 4).These are directly related with the protein contribution and other nutrients that the tree component carry out (Simón 2005).

An important element that should be highlight in the agro- systems, which are managed and used with agro-ecological principles, is that are in a constant dynamic development. These involve, in all cases, a holistic analysis of their components from the experiences, knowledge and interpretation of them. The anthropic component plays a fundamental function in the agro-ecosystems functioning.

When carring out a comparative bio-economical analysis between simple systems (monoculture) and silvopastoral complex systems, as decisive tool in the farm sustainability, Reinoso (2000) found that grazing in a silvopastoral system reached a very favorable cost- benefit relation (1.59 Cuban pesos), mainly due to that the costs per kilogram of produced milk and the cost per Cuban pesos produced were lower in 0.30 and 0.48 Cuban pesos, respectively regarding the monoculture (table 5).

The incorporation of Pennisetum purpureum cv. Cuba CT-115 in different technologies for meat and milk production shows positive results, since it allowed facing the lack of food volume at critical times of the year, when precipitations decreased (Martínez 2001). This grass, from the agro-ecological point of view, has multiple advantages, since it keeps the soil covered the whole year, it is used in grazing, and it generates less input of fossil fuel for the farm and preserves high nutrients return to the soil.  

The experience in a dairy farm of 60 ha, with 30 % of the area with CT-115 as biomass bank for the dry period (Martínez 2006) shows that during the first year, when 12% of the dairy had biomass bank, the food lack in the dry period could be satisfy in 47%, and only 13% with external resources. With the planting of 20 ha in this unit, the biomass bank solved 95% from the lack of the dry.

Studies developed by Diaz (2008), in an area of 14.5 ha, showed that the use of agro- ecological technologies, as grasses and herbaceous legumes association, a silvopastoral system with leucaena and the use of CT-115 for meat production in the tropic, can reach the animals slaughter at 22 months of age, with 445kg of liveweight in 363 days of stayed in fattening and MDG of 838g animal^-1. These results are more relevant, when being obtaining only with an expense of 180kg of supplement per animal which it is slaughter during the whole fattening period.

Similar results obtained Iglesias (2003), when using associate systems of guinea grass(Panicum maximun vc. Likoni) with leucaena for the male zebu fattening (without energy- protein supplementation), although in the dry season the daily mean gains only reached 429 g per animal. This author, when comparing this technology with a protein bank system and grass monoculture (guinea), showed that the accumulated mean gain (table 6) was higher for the association, and higher than 620 g/animal/d, which caused animals with higher weight to 400kg, at 26 months of age.

The associated systems of grasses and legumes, with the minimum use of supplement, are an economically viable option in the tropics for grazing cattle fattening (Cino et al. 2011). Although legumes can have low persistence, because they are more sensitive to high intensity and grazing pressure, stocking rate and size of the animal bite, with appropriate management and supplementation fit, it can obtain higher mean daily gains of liveweight (Diaz 2004).

It can be concluded that the generation and multiplication of productive systems, under agro-ecological principles that privilege the persistence and species coexistence, the high biomass production and maximize the photosynthesis process, they transform into a practical and real alternative to the environmental regulation in cattle agro-ecosystems, because they are able to also generate , environmental services.

During the evolution process, the man developed production systems with simple technologies that were reliable, it was only to exploit these systems with very expensive external components. However, that is not the way the nature has to make reliable, sustainable and less polluting systems. The nature preferred a very different way: to make that the systems were sustainable per amount of components that do the same task, components that can fail and the system continues.

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Received: 7/10/2013
Accepted: 7/6/2016

J. Alonso, Instituto de Ciencia Animal, Apartado Postal 24, San José de las Lajas, Mayabeque, Cuba. Email: jalonso@ica.co.cu