RESEARCH WORK

 

 

 

Evolution of grazing management for dairy production in Cuba. Generated principles

 

 

 

Milagros de la C. Milera, O. López and O. Alonso

Estación Experimental de Pastos y Forrajes Indio Hatuey, Universidad de Matanzas Camilo Cienfuegos, Ministerio de Educación Superior. Central España Republicana, CP 44280, Matanzas, Cuba
E-mail: mmilera@ihatuey.cu

 

 

 


ABSTRACT

The objective of this paper is to analyze the evolution of the most important scientific results related to the management of grazing systems for dairy production in Cuba, during the last 40 years of research. The compilation made allowed to generate a group of principles that rule the management with improved grasses, twining legumes and trees for browsing. The challenges in the conception of milk production systems in Cuba, which constitute the new paradigm: food and energy production on improved grasses in association with fodder, energy, timber and other trees, that cover 80 % of the animals' requirements, were analyzed.

Key words: Trees, grasses, legumes, grazing systems.


 

 

INTRODUCTION

The research related to pasture management for cattle milk production in Cuba started in the 1970's, with the studies on high and low input systems based on grasses in monocrop,; and continued in the 90's, with the use of herbaceous and tree legumes, but with low inputs. In this sense, experiences from several specialists, such as: McMeekan (1963), Voisin (1963) and Stobbs (1978) were taken, and studies with grasses of the Cynodon genus were initiated.

The results of several decades of uninterrupted research generalized from a systemic approach are shown, which have as basis the general principles about the management of pastures and forages for milk production. Those results are integrated with a new philosophy on the conception and agroecological management of current farming systems, where productivity, cost-effectiveness and protection of the ecosystem constitute the equation that supports the sustainability and innocuousness of the production process, with a great impact on the Cuban agricultural sector.

For such reason, the objective of this paper was to provide the different actors of the livestock sector with a set of principles about the management and utilization of forage genetic resources for cattle milk production.

 

I. Principles generated from the studies about grazing management

In Cuba, the monocrop within the Green Revolution was applied differently from other countries, because the rural population was not excluded. With the triumph of the Revolution two agrarian reform acts were passed, whose objectives were to change the existing situation related to richness distribution, to benefit the poorer and to increase production, in order to satisfy the growth of food demand by the population, as a result of income redistribution in favor of the majority.

In practice, in the cattle production areas no chemical fertilizer was applied in excess, which did not affect the soil or the groundwater; while the application of other agrochemicals did not exceed, as average, 40 kg/ha/year (González et al., 2004). The objective of introducing improved pasture and forage grass species was not to eliminate endemic species; on the contrary, this was done to enrich the existing germplasm, because cattle production was a priority.

The studies developed with pastures and forages as main feedstuff for cattle, in intensive systems with improved grasses in monocrop, were conducted to know the potential of the species, to minimize the use of imported supplements. In this sense, great importance was given to grassland management, because there were no previous studies about this topic in Cuba. Such studies along the response given to the problem at that time, served as basis for future projections of the scientific work.

The results related to the production potential of pasture and forage species (Pereira et al., 1990; Lamela, 1991), the response of pastures to stocking rate under grazing conditions (Martínez, 1978; Jerez, 1983), the grazing pressure (Milera et al., 1987; Hernández et al., 1990; Hernández et al., 1994; Pereira and Lamela, 1995), the availability and quality of the species used, the number of paddocks and occupation and resting times (Hernández et al., 1985; Milera et al., 1987), the segregation of grazing areas for forage conservation, the management of animals in a system of leader and follower groups (Jordán, 1984) fulfilling the laws of rational grazing (Voisin, 1963) , the persistence of pasture and forage species under grazing conditions, as well as the management of the protein bank with herbaceous legumes (Pereiro, 1985), when irrigation and fertilization were given priority, were already approached in previous publications. Nevertheless, the generated principles served as basis for later research.

 

I.1 Generated principles for the management of irrigated and fertilized grasses and legumes, in monocrop for dairy production

The improved species, with irrigation and fertilization rates not lower than 250 kg N/ha/year, have potential to produce between 8 and 11 L of milk/cow/day, and the production per area can be higher than 10 000 L/ha.

The stocking rate is the most important element in management and is directly related to the pasture species, its floristic composition, DM availability, fertilization, the strategy of rotation and DM requirements of the animals.

The best response to the intensification of the stocking rate, under irrigation and fertilization, is shown by Cynodon nlemfuensis, with more than 5 cows/ha.

The grazing pressure is the best form of expression of the stocking rate, because it relates the DM availability to the needs of the animal in a certain area. The DM offer should not be lower than 30 kg DM/cow/day, because from such amounts up to 80 % of the DM requirements for medium-potential animals can be covered.

The pasture quality is affected by the increase of the days of stay in the paddocks, due to the reduction of the leaf-stem ratio, the CP content; as well as to the increase of CF, which negatively affects dairy production.

The resting time between grazing periods should be sufficiently long to allow pasture recovery, providing that the quality of the species is not affected so it can be grazed at the optimum moment.

The grazing areas that will be segregated as silage or hay should fulfill the following requisites: the area should be covered by more than 70 % of the species that will be conserved, the resting time should be higher than 45 days to perform the cutting, it should be fertilized with at least 50 kg of N/ha; also the stocking rate, number of paddocks and the time to decide when segregation must be performed within the rainy season (RS) should be considered, because they have a determining influence on the quantity and quality of preserved material.

When several groups of animals are managed, it is essential to adjust grazing depending on the requirements of each one. With the grazing in line, the leader animals should be the ones with higher production; while in the group grazing in independent areas, they should be assigned the paddocks with better pasture and closer to the farm.

The persistence of the species is not affected when the pasture is adequately managed, which means the use of appropriate resting, permanence and grazing pressure. If these requisites are not followed the deterioration of pastures and the invasion of weeds will occur in the paddock.

In the grazing systems that use the protein bank, between 20 and 30 % of the area should be destined for the legumes, which have to be managed with no less than four paddocks and with the cows with higher requirements. Grazing should be restricted, in the morning; and it can be performed in alternate days, without affecting the milk production. The persistence of herbaceous legumes is damaged to a higher extent than that of grasses when the soil, topography, climate and management are not adequate. The production potential depends on the breed: with Holstein cows between 13 and 15 L/cow/day can be achieved, while with the Holstein x Zebu cross 8-11 L/cows/day are obtained.

 

II. Rational management of grasses, herbaceous and tree legumes, without irrigation and with low or no fertilization

In the 80's and early 90's of the 20th century a regressive trend was shown in the cattle herd, due to problems related to the assurance of the feeding basis, associated with: the absence of areas with paddocks, the shortage of fertilizers, the decrease of grazing areas, as well as their loss due to weed infestation. At that time more than 1,7 million pesos were destined to subsidize cattle production (González et al., 2004).

 

II.1 Rational management of pasturelands with grasses

 

Stocking rate and resting time

In a study with three grasses (Panicum maximum, Andropogon gayanus and Cenchrus ciliaris), the global stocking rate of 2 LAU/ha was adjusted to 1,5 LAU/ha in the second year, because the DM availability started to decrease. Nevertheless, after four years of evaluation, the diversity of plant species remarkably increased: 75 in total (Milera, 1995).

When the jump method was used (to graze without pre-established order, just taking into consideration the pasture availability in each paddock), it was proven that in the paddocks with more than one improved grass species the determination of the optimum moment for the pasture to be grazed should be made with regards to the resting time and should consider the objective of the pastureland management, the species that occupied the highest percentage of the area, and the most selected and consumed species to prevent its disappearance.

On the other hand, it was proven that the average resting times in the dry season (DS) were higher than 70 days. This prolongation allowed the fructification of the herbaceous legumes, as well as their dissemination and increase in the frequency of distribution of their populations in the paddocks (Machado et al., 2000).

In these systems the instant stocking rates exceeded 200 LAU/ha and they were managed according to grazing pressure or DM availability, and with restriction of the grazing hours when necessary. The species did not have the same behavior, some of them decreased in their availability and others began to disappear. The instant stocking rate allowed a significant discharge of excreta (17 t/ha/year) which influenced the increase of the edaphic biota (Hernández and Milera, 1996), although it did not cover completely the nutritional needs of the improved species in this soil type.

 

Edaphic macrofauna

The study of the soil biology (the macrofauna, specifically) showed that, after four years of rational management, the number of orders of the most representative organisms increased, due to the presence of other groups, among them: Dermaptera, Diptera, Arachnida and Isopoda, belonging to the classes Insecta, Arachnida and Crustaceae, respectively; which enriched the biodiversity of the pasturelands (Sánchez et al., 1997).

 

Response of the entomofauna

Regarding the results of the phytosanitary evaluation of the grazing area under monocrop conditions (A. gayanus, P. maximum, C. nlemfuensis, Brachiaria purpurascens and C. ciliaris), in spite of not having enough elements to recommend a certain pasture because the phytophagous insects and the symptoms of fungal diseases were minimal , it can be stated that the rational intensive grazing system can influence the insects and pathogens through the different changes that occur, among which are: diversification of the flora (75 species); the reduction of leaf mass to be consumed by the pest at a certain moment; the loss of a host pasture as it does not stand intensive grazing; the short resting time of some pasture species, which causes the animal to graze in the same paddock with higher frequency compared with when it is grazed with the traditional system; as well as the non application of inorganic fertilizers or pesticides (Alonso et al., 2011).

 

Conservation of the pasture production surplus

The utilization of the pasture surplus for conservation is a need in the RS; for such reason, the recommendations for the elaboration of small silos were taken up again. The process of elaboration of the ring silo to preserve pastures and forages or other feedstuffs lasts one day, and improved grasses from the grazing or forage area can be used. If the grasses have low quality, tree foliage with high nutritional value can be added during the process of silage making; in addition, the methodology for its elaboration should be adequately followed (Anon, 2012).

 

II.2 Management of the protein bank

 

II.2.1 With herbaceous legumes

In the systems with protein bank of Neonotonia wightii fertilization and a stocking rate between 2,0 and 2,6 cows/ha were used. In short-term studies, the productions exceeded 10,5 kg of milk/cow/day, saving 1 kg of concentrate feed, because supplementation was offered from the seventh liter produced. However, in studies for more than two years 9,4 kg/cow/day were produced, with calving interval of 393 days. No depopulation of the legume was observed when restricted grazing in the morning was used (Lamela et al., 1995).

The banks of Teramnus labialis were managed with fertilization and a global stocking rate between 2 and 3 cows/ha. The DM availability and persistence had a good performance, while the milk production was 9,5 kg/cow/day (Milera, 1996).

In the case of Lablab purpureus sown as pure stand with minimum tillage, it is possible to perform four rotations with restricted grazing in the morning, and productions of more than 10 L/cow/day are obtained (Milera et al., 1989).

 

II.2.2 With tree legumes

The inclusion of tree legumes in the low-input systems characterized by little or no application of fertilizer to the improved grass constituted a new paradigm, due to the advantages it represented at those moments in which the main affectations were the lack of fuel, lubricants and spare parts, and the increase of the prices of concentrate feeds.

When trees are included in the grazing area it is essential to consider the following requisites: grazing starts after the establishment of the woody plants, while the resting time in the dry season should be between 60 and 70 days to allow the recovery of the trees. The same should be performed when they are subject to pruning, where the management of grazing is based on the development of their regrowth.

The tree is considered established when it reaches a height of 2 m; however, pruning is performed when the plant height is more than 3 m and the main part of the foliage is not accessible to the animal.

The inclusion of tree species in grazing areas started in the mid 1980's, with the development of milk production systems with protein bank based on Leucaena leucocephala cv. Perú. Leucaena was established in a system of P. maximum cv. Likoni in 20 % of the area (fertilized and without irrigation), with a global stocking rate of 2,5 cows/ha. In addition, in the RS the grass was harvested to be ensiled. The milk production was 10,1 L/cow/day (Milera et al., 1994).

In another study, Lamela et al. (2001) obtained a production of 8 L/cow/day in a commercial state farm of 40 ha, where 8 ha were dedicated to the protein bank of L. leucocephala cv. Cunningham, 29 ha to the grass C. nlemfuensis cv. Jamaicano and 3 ha to sugarcane, managed with a stocking rate of 1,7 cows/ha.

 

II.3 Association of trees with improved pastures

 

Nutritional value of the feedstuffs

The research conducted during more than 20 years about the production and utilization of tree legumes allowed to elaborate a technology based on the use of L. leucocephala, Albizia lebbeck and Gliricidia sepium, in silvopastoral systems. Thus, the favorable conditions to apply silvopastoral systems as proper available resource under the current production conditions were created.

In the grass-tree legume association the highest CP and ME availabilities are found, if it is compared with the grass monocrop, which explains to a certain extent the better bioeconomic performance of the herds exploited in such system (Simón, 2011).

 

Influence of the edaphic conditions and the established species on the productive system

In a study conducted with Siboney de Cuba cows of several lactations, Reinoso (2000) compared four agro ecosystems. Systems I and III were constituted by an association of leucaena with cultivated pastures, on a good-fertility soil. System II was also an association of leucaena, but with natural pastures, on a low-fertility soil. Finally, system IV was a monocrop of improved pastures on fertile soil. The animals were fed with commercial concentrate at a rate of 0, 1, 2 and 3 kg/animal/day, respectively. The best daily averages of production per lactation were found in systems I (7,1 kg/animal/day) and III (8,0 kg/animal/day); while the lowest yields were found in systems II and IV, with 5,2 and 6,2 kg/animal/day, respectively.

Sánchez et al. (2008) conducted a study under commercial conditions, during five years, in which cows of the breed Mambí de Cuba were used, grazing in an association of improved grasses (P. maximum cv. Likoni and C. nlemfuensis cv. Jamaicano) and L. leucocephala cv. Cunningham; they consumed 0,46 kg of concentrate feed/animal/day and around 10 kg of fresh sugarcane forage in the DS. Productions between 8,5 and 9,0 kg/animal/day were obtained in primiparous cows during the first three years, and between 7,5 and 8,2 kg/animal/day with multiparous cows in the last two years.

López et al. (2003) also carried out a study with Mambí de Cuba cows, in a system similar to the one used by Sánchez et al. (2008). They found that the dry matter offer was considerable during the year of evaluation, because it exceeded 47 kg/animal/day in both seasons. Nevertheless, there was an excess of CP in the diet (25 and 38 % for the DS and the RS, respectively) and a deficit of energy in both seasons.

The diets with a significant CP content stimulate the increase of milk production at the beginning of lactation, because cows are capable of mobilizing their body reserves of energy to satisfy the demands of required nutrients. On the other hand, the cows that calve with a body condition (BC) between 3 and 3,5 (scale from 1 to 5) are able to produce 20 % more milk than those that do it with a BC of 2,5; and up to 25 % more with regards to those which calve with a BC equal to 4. This implies that obese cows, at the moment of calving, show more difficulty to produce milk (López et al., 2002).

Likewise, it is possible to achieve productions of more than 10 L/cow/day in specialized dairy farms with animals of the breeds Siboney and Mambí de Cuba, when silvopastoral systems (L. leucocephala and P. maximum) and a supplementation with 170 g of concentrate feed per kilogram of milk produced, are used.

 

Study of the entomofauna

The study of the entomofauna conducted in the grazing-browsing area of L. leucocephala with P. maximum showed the presence of a varied quantity of insects interacting with this legume, grouped in 96 species, from which 44 % represent new reports for this plant in Cuba. Likewise, 42 % are beneficial insects, among which bioregulators prevail. On the other hand, in the grasses the typical insects of this vegetation were found. If the ecological indexes are calculated, it is possible to obtain remarkable values of insect diversity in the sampled areas (H' = 0,85 and 2,23 in the case of phytophagous insects; and 2,52 and 2,39 in the beneficial ones, for the tree and herbaceous strata, respectively), due to the presence of trees, the created microclimate and the variability of existing niches. This in turn allows to reach a higher balance between phytophagous and bioregulator insects, favored by the complex interactions that occur in these systems, which are based on the synecological method, the study of communities, that is, individual environments, and the relations among the species that live there (Alonso, 2009; Alonso et al., 2011).

 

Edaphic macrofauna

In the SPS composed by Guinea grass and leucaena, the litter of the tree legume represented the highest weight percentage within the total production, with a higher nitrogen and calcium content than that of the litter from the grass in monocrop. Among the species present, the litter decomposition rate varied in the following order: leucaena higher than Guinea grass in the SPS and higher than Guinea grass as monocrop. On the other hand, the higher values of density and biomass of the macrofauna individuals, the predominance of Oligochaeta, as well as the better diversity, richness and uniformity indexes in the SPS, indicate that the presence of leucaena in the pastureland allows to enhance the biological activity of the soil and to guarantee the stability of the system (Sánchez et al., 2008).

 

II.4 Management of trees with improved pastures multiassociations

In the multiassociation (intensive silvopastoral systems, SPSi) of several species (grasses with herbaceous and tree legumes), with high density of trees (more than 15 000 plants/ha), the availability reached values of 4-7 t DM/ha/rotation in the DS and the RS, respectively. Through microhistological techniques the selectivity of the offered diet was determined, which showed a higher preference for the legumes compared with grasses that had a significant influence on the nutritional quality of the consumed feedstuff. The availability of 25 kg DM/cow/day was sufficient to cover the requirements of the cows that produced more than 8 L/day without supplementation. This system allowed stocking rates higher than 2,5 LAU/ha, because of the high DM production, the high quality and the remarkable diversity of species that characterize it (Hernández et al., 2011).

Another advantage of these tree-pasture systems is related to the environmental services, due to the carbon sequestration, if it is compared with the monocrop -425,2 vs. 9,5 t C/ha (Milera et al. 2010). In addition, they allow higher intensification, because milk productions higher than 6 000 L/ha/year can be obtained.

 

II.5 Use of pedestals

Pedestals guarantee high productions if the whole area is adequately managed, that is, with a systemic approach; only the higher-production cows (in their first 100 days of lactation) are taken to this technological system, but their requirements should be covered throughout the year.

In the system of pedestals VERDEMAR L. leucocephala trees, improved grasses and herbaceous legumes were used. The trees were planted at 4 m between furrows and 1 m between each one within the rows (21 pedestals/ha). Irrigation and fertilization were applied, and the cows only left the system at the time of milking. Azadirachta indica (Neem tree) was planted in zigzag form, providing shade for the cows and contributing to protect the area from pests and diseases. The reproductive results were: 50 % of pregnant cows, 5 % empty, 28 % inseminated and 17 % newly-calved, and a milk production of 20 000 L/ha/year was reached (Verdecia and Falcó, 2012).

In a commercial dairy farm the productive results were evaluated during two years, in a grazing area of 42 ha of improved grasses (C. nlemfuensis), without fertilization, and in an area of pedestals of N. wightii plus Pennisetum purpureum CT-115, with irrigation every 15 days in the DS. The stocking rate used was 7 cows/ha/year and the cows grazed around four hours in the pedestal, in the morning; the rest of the time they grazed in the grass monocrop.

The average production per day of lactation was 8,0; 9,1 and 9,2 kg/cow/day for the first, second and third lactation, respectively (Sánchez et al., 2008).

 

II.6 Portioned grazing

In portioned grazing a part of the area of a dairy farm (around 12 % of the total area) is utilized, in order to intensify its use; for that purpose, irrigation is applied and a high stocking rate is used. In some cases the forage areas or portions of the grazing area with improved pastures, are managed, or also small areas for their development; which are similar to pedestals, but with the difference that in some cases there are only improved grasses in monocrop or associated to trees, without the herbaceous legumes, to be supplied to the higher-production cows (Ray, 2000).

In a system with a total surface of 65 ha, Lamela et al. (2010) evaluated, during a year, an area of 2 ha with an association of P. purpureum CT-115 and the forage trees L. leucocephala and Morus alba, with irrigation in the DS; the productive performance during the first 150 days of lactation of Holstein x Zebu cows, which were given in the DS 5 kg of fresh or preserved citrus pulp (0,83 kg DM), was studied. The stocking rate was 10,0 cows/ha in the RS and 8,3 cows/ha in the DS; the pasture offer, 39 and 31 kg DM/animal/day; and the milk production, 11,6 and 7,8 kg/cow/day, respectively. In addition, the effect of the supplementation with a commercial feedstuff based on the residue of corn distillery (North Gold), at a rate of 400 g/kg of milk produced from the sixth liter of milk, was shown, and 8,5 kg of milk/cow were obtained for the group without supplementation with regards to the supplemented group (10,6 kg/cow/day).

 

II.7 Use of forage from cut and carry protein plants

The forage of the edible biomass of mulberry (leaves and fresh stems) at a rate of 1 % of LW in dairy cows was better utilized when it was supplied chopped, in combination with the restricted grazing of non-fertilized improved grasses, than when it was offered in higher percentage but not chopped. In addition, in crossbred cows more than 10 L of milk/cow/day can be obtained, without using concentrate supplements (Milera et al., 2007).

The use of Lablab purpureus, included in 30 % of the ration of dairy cows, increased in 1,5 L the milk production with regards to the control without the legume (10,7 vs. 9,2 L/cow/day), and allowed to save 1,2 kg of concentrate feed per cow per day (Milera et al., 1989).

 

II.8 Generated principles

In the systems with non-fertilized improved grasses the areas should not be managed above the carrying capacity, because it would lead to the decrease of the DM availability and the persistence, for which the restriction of grazing is a need in the DS.

In areas established with more than one improved grass, the resting time should be arranged taking into consideration the most consumed or selected species, those with higher number in the paddock and those that are in plan to be preserved, to prevent their disappearance.

At the end of the RS and during the DS, considering the rainfall and the recovery of the species, resting times of more than 70 days should be provided.

In the systems with rational management not all improved grasses respond in the same way to high instantaneous stocking rates (200 LAU/ha), for which the availability and population can decrease and thus their persistence can be affected.

In the rational management of grass-legume associations, the prolonged resting times have beneficial incidence on herbaceous legumes because, in general, they fructify in the DS, which allows to increase their quantity and distribution frequency in the paddocks.

When pasturelands are managed with high instantaneous stocking rates a high discharge of excretions takes place which benefits the increase of the edaphic biota (insects, arachnids and crustaceans, as the most representative groups) and the growth of a higher-quality regrowth; nevertheless, the pasture requirements depend on the species, the grazing hours and the soil type.

Intensive rational management without use of agrochemicals, with adequate resting times and high utilization of pasture by the animals), prevents a significant appearance of insects and pathogen microorganisms, which can be also favored with the increase of the diversity of plant species.

In the production systems with neither irrigation nor fertilization, the segregation of grazing areas or the use of forage areas for silage or hay making should follow the principles stated in epigraph I, and the small-size ring silos can be used, which allow to improve the silage quality if mixtures of improved grasses with protein plants or additives, such as urea or molasses-urea, are used.

In the grazing systems that use the protein bank of tree species, with equal management as the one referred to in epigraph II, the production potential is between 10 and 12 L/cow/day. The requisites for the establishment and pruning management will be similar to the ones described below for the tree-pasture associated systems.

In the associations of trees and improved pastures, the following should be fulfilled: a) the woody plant is considered established when it reaches a height of 2 m, as average; the tree pruning is performed when the lowest part of the foliage is not accessible to the animal and its height is more than 3 m; b) only 50 % of the plants is cut annually, for which they are pruned every two years; c) pruning is made at a height between 1 and 1,5 m in the DS (March-May), in the paddock where the animals are grazing, so the cuttings in every rotation are spread out, so that the foliage serves as a protein complement of the diet (1-2 kg DM/cow/day); d) the stocking rate can be 1,2-1,5 LAU/ha; e) the resting time in the DS should be managed taking into consideration the recovery of the tree (60-70 days).

The potential of SPSs regarding milk production (8-12 kg/cow/day) will depend on the soil and climate conditions, the potential of the cows and the tree density and the improved grass that are used, because they have higher biomass availability and quality with regards to the monocrop systems of improved grasses.

The associations of trees with improved pastures on good-fertility soils and the supplementation with a certain quantity of concentrate feeds propitiate better milk productions in medium-potential cows, than the systems with trees on low-fertility soils and with natural pastures, or the systems without trees even when they have been established on fertile soils, with cultivated pastures and, also, an acceptable level of supplementation with concentrate feeds.

Regarding the edaphic macrofauna, a higher richness of organisms (with predominance of Oligochaeta and earthworms) is found in silvopastoral systems, with regards to the grasses in monocrops; as well as higher diversity and uniformity values, which indicates that the presence of trees in the grassland allows to enhance the biological activity of the soil and to guarantee the stability of the system.

The associations of trees with improved pastures propitiate the presence of different habitats for insect species, because a microclimate is created that favors their development; in addition, they allow the establishment of complex interactions that imply higher balance between phytophagous and bioregulator insects. This favors the latter and other beneficial organisms among which are pollinators, coprophagous animals and OM decomposers, which are responsible for maintaining the biological stability of these systems, at pastureland level.

In the multiassociation (SPSi) of many species (grasses and herbaceous and tree legumes) with high density of trees (15 000 plants/ha), the diversity of the offered and consumed diet, with a higher component of legumes than grasses, influences the nutritional quality of the feedstuff, for which in the systems with irrigation and fertilization and without concentrate supplements the same results can be obtained with 25 kg DM/cow/day or with offers between 30 and 50 kg DM/cow/day,.

The associations of L. leucocephala with improved grasses (P. maximum and C. nlemfuensis) on moderate-fertility soils allow a CP intake between 20 and 35 % above the needs of the medium-potential cows in lactation (7-9 kg/animal/day); while there is an energy deficit between 3 and 10 %.

The high CP content of the diet of the animals in associated systems stimulates the increase of milk production at the beginning of lactation, because the cows are able to mobilize their body reserves of energy to satisfy the required nutrient demands.

The cows managed in associations of improved pastures with leucaena, which calve with a BC between 3 and 3,5, have 20-25 % more potential for milk production with regards to those that calve with a BC lower than 2,5 or higher than 3,5.

The pedestals and portioned grazing should be managed with a systemic approach and should follow the principles of pasture management, because the cow shows its highest production in the first 100 days of lactation which is when this part of the area is used; however, it has requirements since before parturition which should be covered to guarantee replacement and milk productions.

In systems with improved grasses, without fertilization, the use of the M. alba forage (leaves and fresh stems) at a rate of 1 % of the LW in crossbred dairy cows and the restricted grazing allowed productions of 10 L of milk/cow/day, without concentrate supplements. With the inclusion in the ration of 30 % of the forage of L. purpureus, similar results can be reached.

 

III. The new challenges

It is necessary that milk and beef production is based on systems that use forage plant resources with different approaches: mixed banks of protein plants, silvopastoral systems, high-yielding grasses, etc., due to the price of supplements and as contribution to more than 2 million hectares, for the adaptation and mitigation of the climate change.

In addition, these systems should consider the growth of the cattle inventory and the genetic quality of the animals, because of their potential in biomass production, animal production and health. This requires knowledge, investments and evidences by the farmer, which implies a complex process.

The inclusion of renewable energy sources in cattle production systems is a challenge. In agroenergetic systems promising results are observed in the installation of wind pumps, biodigesters and gasifiers in areas dedicated to animal production (milk and beef), as well as in those in which innovation has allowed the integration of the cultivation of biodiesel-producing oil plants. Among the evaluated species is Jatropha curcas, which is adapted to low-fertility marginal soils and can be included associated to agricultural crops and also to pastures.

In Cuba there are only 0,023 trees/inhabitant, for which taking them to cattle production areas constitutes an action not only of animal welfare and adaptation, but also of mitigation; because in addition to all their advantages, forage trees also decrease methane production in the rumen.

 

FINAL CONSIDERATIONS

The most important aspect in the extension of results to the productive practice is to consider the principles or laws that generated them and to adapt those results to the conditions of each site, without neglecting the protection of the environment and the farmer's knowledge. That is the best way of contributing to local development, which represents a privileged space to enhance economy and it is the ideal niche for innovation.

 

 

 

Received: December 20, 2012
Accepted: May 21, 2014