Mexico (Estados Unidos Mexicanos is the official name) is in the southern
portion of North America, between 14° 32´ and 32° 43' North and 86° 42´
and 118° 27’ West. It is bordered by the
According to the 2000 Census, Mexico’s population was 97,483,412; population
growth rate decreased from 3.4% in the nineteen-sixties to 1.8% in the
nineteen-nineties and the proportion of rural population which was 49.3%
in 1960 had fallen to 25.4% in 2000 (INEGI, 2003). Due to decreases in
birth and death rates, the proportion of young people (age <15) fell
from 44% in 1960 to 33% in 2000 (According to the World
Factbook the July 2006 population was estimated at 107,449,525 with
a 1.16% growth rate). Population density is very high in Mexico City and
the State of Mexico (911 per km2), in other states of
Central Mexico it is 153 km2, in Central West Mexico it reaches
80 per km2, is lower in Southern Mexico (49 per km2)
and lowest in Northern Mexico (20 per km2). Migration
Indigenous population, colonization, independence and
In 1519 the Spaniards began their conquest of
The Viceroyalty of the New Spain was the most important viceroyalty in
the Spanish empire. Its natural resources - such as silver -
and the high taxes that the Spanish Crown imposed on the population, flowed
to the metropolis. Combined with this, absence of liberties and the political
control exerted by the peninsular Spaniards,
generated deep resentments among the population of the colony. Following
the libertarian principles of the French Revolution, the struggle for
independence started in 1810. After gaining independence in 1821, a long
period of civil wars started between followers of two different ideas
of nation: the conservative monarchy and the liberal federal republic.
In this context of internal wars and extreme weakness,
Between 1857 and 1867 clashes between liberals and conservative were
very intense. The conservatives sought the support of the French emperor
Napoleon III who prompted the establishment of the empire of Maximilian
of Hapsburg in
Empowered in 1876, Porfirio Díaz established a dictatorship that lasted until 1911. His policy was based on modernisation of the whole country through building railroads, promoting mining, encouraging production of agricultural goods for export, giving support to henequen (Agave fourcroydes) and rubber plantations, upholding the extraction of precious woods, endorsing commerce and the banks and sponsoring the investment of foreign capital. His agrarian policy was directed at increasing large, landed estates at the cost of communal lands and small properties. These estates (haciendas) aimed to satisfy the demand of i) the internal market and ii) products for export.
The main beneficiaries of Diaz’s project were the agrarian oligarchy,
the military elite, foreign companies and the ecclesiastical hierarchy.
Social inequity, deprivation of lands and the exploitation of peasants
and workers, caused constant rebellions and social
struggles, which were repressed by the dictator. These conditions favoured
the beginning of the revolution, which started in 1910 after electoral
fraud against the opposing candidate Francisco I. Madero. The social and
political reforms sought by the revolutionaries were expressed in the
Constitution of 1917, establishing the principle of national sovereignty
on all natural resources, agrarian reform, labour rights and free, obligatory,
and secular education. This project of national capitalist development
was accomplished during the government of Cárdenas (1934-1940) with measures
such as agrarian reform, expropriation of oil companies, laws that guaranteed
labour rights and the enlargement of the educational system. To achieve
these reforms, Cárdenas mobilized labourers and peasants. He transformed
the State into the driving force of economic growth and structured the
internal market. Cárdenas consolidated the Mexican political system based
on the president and the State Party; this was the origin of the PRI,
the party that ruled
Based on import substitution, the industrial development of
Environment and agricultural production
These conditions set clear limits to the agricultural use of land, only 20.6
million ha (10.5 % of the territory) are cultivated of which 25% are under irrigation
(SIAP, 2004). Pastoral use of land is widespread, particularly in arid and semiarid
After the nineteen-seventies, national agricultural production has been unable to cope with the needs of the increasing population and imports form an important proportion of domestic supplies (Figure 3). For dairy products the most critical period was between 1985 and 1994. In the cases of cereals and meat, after the onset of the NAFTA and when the economic crisis of 1995 was bridged, the proportion of imports in domestic supplies have been increasing at a rate of more than 2 percent per year. As a consequence the negative balance of trade reached a record amount of US $ 3,721 million in 2002 (FAOSTAT, 2004). The Gross National Income (GNI) per capita has been increasing and in 2002 amounted to US $8,970 (adjusted to US $ values of 1995), however the proportion of agriculture, forestry and fisheries in GNI decreased from 8% in 1990 to 4% in 2002 (Presidencia de la República, 2004). In 1982 the agricultural sector entered a crisis and since the second half of the nineteen-nineties that crisis has worsened. Mexican farmers receive little government support and as agriculture is further integrated in a multilateral trading system, Mexican farmers are being increasingly exposed to competition by highly protected (subsidised) agricultural systems of developed countries. This uneven competition is having adverse consequences on the development of the sector (Amendola, 2002; Gómez and Schwentesius, 2004), which shows in the small 1.6% annual growth (in terms of Gross National Income) for the period 1990-2002 (Presidencia de la República, 2004).
The value of the main agricultural products in two periods, 1990-1996 and 1997-2002 is summarized in Table 1. By the beginning of the twenty-first century beef, fruits, vegetables, maize, milk, poultry, pork and eggs formed 80% of the value of agricultural products. Between the two periods considered, the overall value of agricultural products decreased by 7%, but the evolution in the past few years has been uneven. The value of crop products only increased in the case of vegetables and showed a dramatic 32% decrease in the case of basic crops (cereals, pulses and oil crops). The value of poultry products increased sharply (28%), those of dairy products and eggs showed modest increases (7%) while the sum of values of other products decreased 8%. Within the ruminant sector, cattle products account for more than 95% of the value.
This description is based on the document “Suelos” by Irene Sommers Cervantes and Silke Cram Heydrich, technician and researcher, respectively, of the Instituto de Geografía, Universidad Nacional Autónoma de México, which appears on line at: http://www.union.org.mx/guia/tesorosdelplaneta/Suelos.htm
It is very difficult to classify soils due to their extreme variability so several classification systems have risen throughout the years. In most cases, a soil classification is adapted to the expectations and usefulness they represent for a particular nation, making it difficult to establish equivalencies among classifications. However, the FAO in collaboration with UNESCO proposed a system simple enough so as to be applicable by any nation, regardless of the degree of in depth study that such soils had been subjected in the past.
This system was adopted by México through the National Institute of Statistics, Geography and Informatics (INEGI, its Spanish acronym), and served as the basis to establish an inventory of soils of the Mexican Republic (see Figure 5 and Table 2). Recently, the Geography Institute of the National Autonomous University of México published the National Atlas of México (Instituto de Geografía, 1991) which updates part of the original information from INEGI, and is used here to establish the soil types and the area covered by each soil unit within the country and its climatic regions.
Since climate is one of the factors that exert the most influence on soil formation, they were grouped within the 11 climatic regions of México, as defined by the Geography Institute.
Then, the objective is to present a general overview of this subject in a short space. For this reason, it must be mentioned that our generalizations may not be valid if applied to any particular cases.
The soils that characterize this region are feozems (37%), regosols (16%), vertisols (14%) and luvisols (8%). Andosols (8%) are formed from volcanic ash, so they are associated with mountains. The surface layer is very loose and abundant in organic matter; with some frequency there is a hardened layer with a deficient drainage that makes the soil susceptible to erosion. Since these soils are distributed in temperate as well as in tropical climates their use varies significantly; forestry must be the preferred use, because they have some limitations for agriculture: they adsorb P and are relatively acid leading to Al toxicity; besides cultivation is not possible due to steep slopes. Andosols are present mainly along the volcanic axis of the country. Other soils present in minor proportions are cambisols (4%), calcisols (4%), and leptosols (4%). Another important soil unit is planosols, which are rare in México and mainly found along rivers and estuaries; their formation requires very marked and alternate dry/humid seasons. They have a hard layer close to the surface which causes flooding in the rainy season, which leads to a delayed decomposition of organic matter. These soils are poor in N, K and Ca and have very limited agricultural use. Castañozems, also present in this region, only occupy 2% of the area.
As shown by Table 2 and Figure 5, the soils with the widest distribution in México (65%) are shallow, less developed soils (leptosols, regosols and calcisols), with low cropping potential.
The more fertile and cropped soils (feozems, vertisols, cambisols and luvisols) occupy only 26% of the Mexican Republic. These soils are subject to intensive agricultural exploitation which compromises their potential productivity and sustainability.
The regions with the greatest soil diversity are the Centre and the Gulf of México. Both are subject to high population densities, which promote multiple pressures on the soil resource. Among them are: land demand for housing, roads and industry, as well as for refuse disposal (of both human and industrial origin).
Other productive activities that represent risks for soil resources are: mining that fortunately does not coincide with crop productive regions, but affects extensive areas and residues bury soils; oil production that generates large amounts of toxic substances that spill to soils which have no buffer capacity for this type of impact; and irrigation which leads to soil salinity (secondary impact) which is already affecting crop productive areas of the country like the Central Pacific and Northeast regions.
At a continental scale, tropical storms during summer and autumn (Figure 6) and cold polar fronts in winter and spring (Figure 7) are the main factors influencing climate in the Mexican Republic. However, relief has a major role in producing the climatic diversity of the country: There are two main mountain chains, Sierra Madre Oriental and Sierra Madre Occidental that run north-south along both coasts and meet at the Nudo Mixteco (Mixtec Knot) in the South of the country, close to the Tehuantepec Isthmus. There is a plateau between the two mountain chains, divided into a northern and a central plateau, the former being at a lower altitude than the latter; along the middle of the country, from west to east, there is a distinct volcanic mountain chain called the Volcanic Belt.
Therefore México has climates from the hot with mean annual temperatures equal or higher than 26 °C, to cold ones, with temperatures below 10 °C. However, temperatures range from 10 °C to 26 °C in 93 % of the territory. Hot humid and sub-humid climates cover 23% , temperate humid and sub-humid cover 21%, while dry and very dry ones cover 49% (Figure 8).
Due to its geographical location, the climate of México is tropical, with high temperatures (almost always above an annual mean of 18 °C), that vary according to altitude. Even though below 1,000 metres the northern zones of the country fall within the 20 °C annual isotherm, the thermal range is over 10 °C reaching sometimes 20 °C. On the contrary, below 20° N , the thermal range is less (frequently below 5 °C) and increases only inland at higher altitudes, never reaching 10 °C.
Rainfall varies to a great degree between the different regions; there is a humid region, to the east and south where annual rainfall can be above 800 mm and a dry region that extends to the west, centre and north. The rainy season is monsoonal, taking place in summer, and rains are convective. Since the country is located in the easterlies zone, there is a regional maximum rainfall to the east, but conditioned to a great degree by relief, since mountain chains isolate the central and northern plateaux from humid winds coming from the sea (Figure 9).
Another differentiating element is altitude, which determines the division into hot, temperate and cold areas. The hot areas go from sea level to 800 metres., where sugarcane, cocoa and rice can be grown; temperate zones are from 800 to 1,700 metres and coffee and citrus can be planted, although from the 1,500 metres there is a great risk of frosts; the cold lands start from 1,700 metres with three distinct levels: up to 3,250 metres where it is possible to grow wheat, potatoes and temperate fruits; up to 4,000 metres a conifer and grassland belt; above 4000 metres there is perennial snow.The location of México within the inter-tropical zone of atmospheric circulation affects the climate significantly, since it is affected by the easterlies and the inter-tropical front, on one side, and the northern hemisphere tropical anti-cyclone, on the other. In summer, the anti-cyclone shifts up north and only covers the Baja California peninsula, the only dry region at that season. On the contrary, the inter-tropical front, hot and with abundant convective rainfall, covers the southern part of the country, while the easterlies hit the Gulf of México coast, penetrating inland toward the centre of the plateaux, where they collide with the tropical air-mass from the Pacific Ocean, creating the so called “Mexican front”, which aligns itself along both mountain ranges. This phenomenon results in a hot and humid summer in the whole country in most years. In winter, the tropical anticyclone invades México covering the central plateaux and the western coast, except northeast California, while the easterlies affect only the middle part of the east coast. Then, dry weather dominates over the whole country, without a great reduction in temperature, but in the high altitudes; only the more eastern part of the country gets some rains, although of a different origin.
According to the above, there are four main climates in México (Figure 10): hot, dry or desert type, temperate, and cold, with variations within each one of them. Figure 10 presents the areas covered by the three main types since cold types represent around 7% of the country’s area and are of little importance for animal production from grasslands.
The hot climates show high mean annual temperatures (18 °C to 21 °C for the coldest month) and rainfall above 750 mm/year, appearing in flat lands below 1,000 metres and to the south of the Tropic of Cancer. There are three main subtypes:
The dry or desertic types receive less than 750 mm of rainfall per year. These present two subtypes:
The temperate climates are basically highland. The mean annual temperature is above 10 °C and the mean minimum is above zero for the coldest month and temperatures in July above 18 °C. The differences in amount and distribution of rainfall gives several subtypes:
This variability in climate conditions has shaped the type of cattle production system developed in the different regions of the country. Then, one can find dairy production in the highlands based on Holstein cows grazing introduced temperate species with little use of supplements, and intensive dairy based on similar cattle under housing and receiving total mixed rations (TMR) mainly produced entirely outside the farm, and also tropical dairies with crossed cows grazing tropical grasses (native and introduced).
Agro-ecological zones and their major agricultural enterprises
De Alba (1976) identified five major agro-ecological regions establishing
a link between climates, forage production and animal production systems:
i) Arid and semi-arid, ii) Temperate, iii) Mountains, iv) Humid tropical
and v) Dry tropical occupying 40%, 10%, 25%, 13% and 12% of the area,
respectively (Figure 2). Arroyo (1990) based the identification of eight
Agricultural Regions (Figure 1) in the major socio-economic regions identified
by Bassols (1990): 1) Northwest (NW), 2) North (N), 3) Northeast (NE),
4) Central west (CW), 5 Central south (CS), 6 South Pacific (SP), 7 Gulf
(G) and 8 Peninsula (P). Some ecological and agricultural characteristics
of these regions are summarized in Table 3. There is a certain degree
of correspondence between regions identified by De Alba (1976) and Arroyo
(1990) as shown in Figures 1 and 2 and Table 2. Northern Mexico is predominantly
arid and semi-arid, (about 20% of its area falls within the Mountains
region of De Alba) Central
Considering the development of agriculture Arroyo (1990) gathered regions into three groups, which agree with groups of states defined by FAO-SAGARPA (2001): i) Northern Mexico (NW, N and NE) characterized by high availability of resources (irrigated land, infrastructure), intensive adoption of high-input modern technology, high proportion of private property of the land and homogeneous in the degree of development, ii) Central Mexico (CW and CS), very important in terms of production but heterogeneous in the degree of development and iii) Southern Mexico (SP, G and P), where agriculture is mostly practiced by poor native peasants with low adoption of high-input technologies. Considering data from Table 3, the NW region appears far more developed than the rest of the country in terms of percentage irrigated agriculture, value of agricultural products per ha of agricultural land and high maize yields. The P region is at the other end of the range of development.
The ratio between the value of crop and animal products in the past few years (calculated from data in Table 3) depicts the regional evolution of the relationship between agricultural production and animal production. The accent in NW and SP lies on crops, in NE, CS and G there is a slight dominance of crops, while in N and CW there is a slight dominance of animal production and P is clearly devoted to animal production. However, if the trend of changes of the past decade is kept during the coming years, within a decade only NW, SP and G should remain as clearly agricultural and in the rest of the regions animal production should be the dominant activity. Ruminant production prevails in N, NE, SP and G, while in NW and P pork production is most important and in CW and CS poultry production prevails (Table 4). Within ruminant products, cattle milk and meat production represented (in the average 1990-2002) more than 95% of the value of ruminant products.
The following description considers agro-ecological regions pictured in Figure 2 and an updating of statistical data (SIAP, 2004) based on agricultural regions depicted in Figure 1. Dairy production grew more quickly than meat production and the increase in ruminant products was related to the increase in area sown to forages other than rainfed permanent pastures (R² = 0.81). Therefore, the analysis of changes in the different regions is based on changes in the dominant ruminant products (cattle milk and meat) and changes in the area sown to forages. The areas sown to permanent rainfed pastures were not taken into account because statistical data of SIAP (2004) on those areas are rather incomplete, leading to underestimation. The descriptions of changes are based on the comparison of averages of two periods: i) 1990-1996 and ii) 1997-2002.
Important proportions of N and to a lesser extent of NW and NE lie in the Mountain region described by De Alba (1976), located in areas with altitude higher than 1000 m above sea level. Forestry is of main importance in this region; however, traditional, low-input cattle and sheep production systems of low productivity are carried out (Cantú, 1990).
According to De Alba (1976) and FIRA (1994), extensive cattle rearing is one
of the main animal production system in Northern Mexico, most calves are exported
to be fattened in feedlots in the USA and the rest remaining in the region to
be finished in feedlots (sometimes with a previous phase under intensive grazing
of sown pastures). Between 1993 and 2003, the N and NE regions plus the state
Sonora in NW accounted on average for 94% of the calves exported to the
In Chihuahua, Coahuila and Durango, intensive dairying displaced beef as the main animal production system and the increase in value of ruminant products was highest in this group of states (39%). The area sown to irrigated and rainfed forages increased strongly mainly associated with intensive dairying systems (R² between dairy production and sown area is 0.80). In Baja California, Baja California Sur, Sonora, Sinaloa, Nuevo León and Zacatecas the accent is on beef cattle, which is based on natural grasslands and rainfed annual forages and pastures; the growth of production was here much lower (20%). Nayarit is a rather different state because it is mostly tropical (67%) and also has a high proportion of area (33%) of temperate climate in the mountains; ruminant production systems are less developed in this state and the area sown to forages is very low. Tamaulipas also presents a different situation within Northern Mexico, it has an large area of highly developed agriculture and is by far Mexico’s biggest sorghum producer (51% of the total); much of the animal production takes place in its tropical areas (26% of the total area) resembling the production systems of Southern Mexico with a very low increase in value of ruminant products (5%). However, growing beef cattle on sown pastures is becoming an important system in this state.
Due to the high population density and the mixture of cultures, there are many production systems in this region . Traditional agriculture, with maize and beans as main crops, has always been important. In some areas commercial agriculture has also been important, with sorghum sharing an increasing area. The nearness of Mexico City encourages intensive production of vegetables, fruits and flowers. Intensive dairying based on lucerne and forage maize is a major system; while family based dairy systems also play an important role (Amendola, 2002). Extensive cattle breeding is important in CW and it is practised in underdeveloped zones of CS by very small farms (Castelán et al, 1997). In the last two decades this region produced 27% of the national beef; feedlots where calves are finished play an important role therein (FIRA, 1994). Sheep production is important in this region, with a clear distinction between the phases of breeding and finishing (De Lucas et al., 1993). Concurring with data on Table 3, De Alba (1976) states that grains grown in El Bajío are partially used in this region as feedstuffs for swine and poultry.
Grain maize, the traditional crop of Central Mexico, is being replaced by crops
aimed for animal feed; comparing averages of 1990 - 1996 and 1997 -
2002 the area sown to grain maize was reduced by 146,000 ha, while that sown
to forages and grain sorghum increased by 124,000 and 98,000 ha, respectively.
Cattle production in Central Mexico is more clearly directed to milk production
than in Northern Mexico (10.4 and 5.4 kg milk per kg meat respectively). As
in Northern Mexico, differences in the development of ruminant production within
this region have been closely linked to the accent on beef or intensive dairying.
Jalisco leads animal production in
The main animal production systems in the Humid Tropics are Dual Purpose aiming to produce milk and calves (Améndola, 2002) and the finishing on sown pastures of calves from the Dry tropical region (De Alba, 1976); in the past decade sheep production systems based on hair sheep (mostly Pellibuey) have been gaining importance (Olazarán and Rojas, 2001). In the Dry Tropics cattle systems are based on grazing the native vegetation (production of calves that are finished in the Humid Tropics), or sown pastures (Dual Purpose system).
Areas of Veracruz, Puebla and Chiapas with annual rainfall over 1,000 mm are characterized by deciduous forests with Liquidambar styraciflua as main species; in some parts of these areas the forest has been replaced by pastures of Kikuyu grass (Pennisetum clandestinum) on which dairy and sheep systems are based. These systems are more intensive and productive than ruminant systems in other parts of the Mountain Region (De Alba, 1976).
Contrasting with the rest of the country, in Southern Mexico the area sown to grain maize increased by 16% in the period considered. Cattle production in Southern Mexico is more clearly directed towards meat than in the rest of the country (2.6 kg milk per kg meat), and no changes in that emphasis on meat production took place in the last few years. Animal production systems in Southern Mexico have not been very dynamic in last few years with only 10 and 7% growth in dairy and beef production respectively. Even though irrigated forages are not yet important in Southern Mexico, their area increased 24%, revealing a trend of intensification of ruminant production systems. Within the SP region cattle production in Chiapas and Guerrero has been more dynamic than in Oaxaca and Colima. In the Gulf region, animal production in Veracruz (a very important producer) has been growing steadily while it stagnated in Tabasco. In the Peninsula region Campeche and Quintana Roo have been more dynamic than Yucatán.
|4. RUMINANT LIVESTOCK PRODUCTION SYSTEMS
The description of animal production systems under temperate and arid or semi-arid regions will focus on cattle systems since those are by far the most important, representing more than 95% of the value of ruminant products.
Dairy systems in the Plateau and North of Mexico
Dairy production systems in the
Amendola (2002) reports that dairy farms in La Laguna are the biggest
in Mexico, and their size is still increasing; productivity in La Laguna
is the highest in
The states of
Reliance on family labour is a distinct attribute of the Semi-Specialised
and Family-based Dairy Systems (Muñoz et al., 1995). However, there
is a transition between very small farms that rely exclusively on family
labour and big farms of the Specialised System where all labour is hired.
Considering farms classified as Semi-Specialised and Family-based, the
proportion of family labour decreases with increasing size of the farm.
Agreeing with data in Table 5, Amendola (2002) states that with farms
above 20 cows per farm, family labour begins to lose importance in the
Amendola (2002) summarised some of the differences among farmers of the Semi-Specialised and Family-based Dairy Systems. Small Family-based dairy farmers do not consider dairy production as the main source of incomes. In many cases of small dairy farms, arable agriculture appears to be highly integrated with dairy production, while bigger farmers devote all agricultural land to grow forages. Self-consumption appears to be an important aim of dairy production on very small farms, but that is not the case on bigger farms. In very small farms of the Family-based System buildings are extremely rudimentary and are generally in the backyard, milking is by hand and feeding strategies might vary even among communities of the same region, including grazing crop residues and roadsides, utilisation of local by-products, purchased concentrates, pastures and forage crops. On the other hand, on bigger farms of the Semi-Specialised Dairy System, animals are housed at least part of the year, buildings might include yards, cowshed, milking parlour and storeroom, and some farmers own a vehicle and a forage harvester; milking machines have already been incorporated in this kind of farm. Productivity on most farms of the Family-based dairy system is lower than 4,000 kg cow per lactation, whilst on most farms with more than 20 cows it is higher. Lower production in the dry winter of the Plateau has been reported for both systems.
Production costs in dairy systems of the Plateau and
North are high. Amendola (2002) reviewed reports of production costs and
concluded that there were no important differences between systems in terms
of feeding costs, which averaged US$ 0.20 per litre representing 57% of total
costs. Those feeding costs amounted to 92% of average theoretical world price
during the nineteen-nineties, so the competitiveness of Mexican dairy farmers
is weak. This has led to research aimed to design systems of dairy production
under grazing for temperate and arid or semi-arid regions to reduce feeding
costs. In the nineteen-nineties, FIRA promoted technological packages to convert
farms of the Semi-Specialised Dairy Systems based on permanent housing and pen
feeding into a system based on grazing. These packages were based on research
carried out by INIA-INIFAP – the National Institute for Agricultural Research,
Chapingo University and FIRA on stations under irrigation in sub-humid to semi-arid
temperate climates. Simultaneously, INIFAP worked on the improvement of the
system used by small farmers in humid temperate climate and the University of
the State of
The Tropical Dual Purpose system
The system is based on grazing native and sown pastures. Percentage of
area with sown pastures decreases southwards from 94% in San Luis Potosi
to 60 % in Tabasco. Cynodon plectostachyus and C. nlemfuensis
are the most frequently used grasses. Low forage availability in the dry
season is the main factor limiting milk production but very little is
done about it; only 30 % of farmers provide supplementary feeding – mainly
molasses – in the dry season, and only 1% of farmers grow forages for
cattle during the dry season. Fertilization is used by only 10% of farmers.
Other management practices such as weed control and some kind of organisation
of grazing (rotational or by types of animals) had already been adopted
by a majority of farmers. Over all management practices, adoption of technological
innovation increases with farm size. Most cattle are zebu crosses with
Brown Swiss, but the productivity of zebu Holstein crosses is higher.
The proportion of incomes from milk is over 50 %, but reacting to price
fluctuation, farmers might change that proportion by increasing or decreasing
the proportions of cows that are milked. Different institutions have promoted
technological packages supposed to increase the productivity of tropical
dual-purpose systems. Rotational grazing is the main component of these
packages, but adoption has been rather low (Amendola, 2002). Mc Dowell
(1996) doubted the adequacy of extended technological innovations and
stated that there were few, if any, reasonable technological paradigms
for tropical regions of
Beef production systems in Northern and Central Mexico
Extensive cow-calf production is a major system in Northern Mexico under arid and semiarid conditions. Calves are mostly exported to feedlots in the USA; between 1993 and 2003, six states of the north (Chihuahua, Sonora, Durango, Coahuila, Nuevo León and Tamaulipas) which average 74% of their area under arid of semiarid climate, exported 0.91 million head per year to the USA, sharing 94% of the national export of that kind (SIAP, 2004). The system is mostly based on uncontrolled grazing of native vegetation. With a short period (90 to 120 days) of fair feed availability allowing the growth of the offspring and reasonable chances for the cow to conceive during the rainy season, the system depends on the sale of all male calves before the onset of feed scarcity (De Alba, 1976). Villareal (1994) identifies three periods in this system: i) between 1650 and 1950 uncontrolled grazing of native vegetation; ii) between 1950 and 1990 genetic improvement of cattle by crossing with European and Zebú breeds, adoption of some forms of rotational grazing and sowing pastures with exotic species; and iii) after 1990 adoption of some forms of more intensive rotational grazing (short duration – high stocking density). By 1991 already about 1.8 million ha had been sown with buffel grass (Cenchrus ciliaris), increasing the carrying capacity of the system on average 2.8 times (Saldívar, 1991). According to FIRA (1986), with an average carrying capacity of 18 ha AU-1, defective distribution of watering places leads to simultaneous over and undergrazing; genetic merit of cattle is fair to low, production parameters and organisation of farmers are unsatisfactory; calving percentage ranges between 55 and 65%, live weight at weaning ranges between 160 and 170 kg and utilities per cow are lower than US $120 year-1. The system’s proneness to climatic hazards like the long-lasting drought between 1991 and 1996 (Ramos et al., 2000), is a main constraint which in Figure 11 is clearly depicted in the 25% reduction of the stock of Northern Mexico – excluding the partially tropical Tamaulipas and Nayarit. Feeding during the dry period is a key issue of the system. The use of supplementary feed is rare among small farmers of Central Mexico (Ramos et al., 2000), but for bigger farmers in Northern Mexico it is a regular practice amounting to 14% of production costs (Ramírez et al., 2003). Using small areas of irrigated pastures to complement range areas during the dry winter has proved to give sound biological and economical results (Sánchez et al., 2001; Ramírez et al., 2003).
Finishing steers in feedlots has been gaining importance due to two factors (Saucedo, 2003): i) a shift in consumer preference for meat from younger feedlot-finished animals than those finished on pasture (which is more usual in the humid tropics) and ii) stricter sanitary import controls by the USA reduced the export of calves and that surplus is being fattened in Mexican feedlots. According to Saucedo (2003) this activity takes place near to grain producing areas, since grain (mostly yellow maize and sorghum) is the most important input. The states where finishing in feedlots has grown fastest are Sinaloa, Sonora, Nuevo León, Querétaro and Jalisco. Enterprises in Northern Mexico are bigger (ranging between about 300 and more than 4,000 head finished per year) and use more modern technology than those in Central Mexico. Diets are based on cereals, conserved forages, crop residues and industrial by products, the use of growth implants is frequent, liveweight gains are about 1.2 kg head-1 day-1. Grazing of irrigated pastures (e.g. Rodríguez et al., 2001) is usually practiced to bring weaned calves to a weight close to 300 kg in order to reduce costs of the finishing process; in these conditions liveweight gains range between 0.65 and 0.85 kg head-1 day-1.
Beef production systems in the tropics
Cow-calf enterprises in the Humid Tropics on average own 91 cows with an stocking rate of 0.52 cows ha-1, calving percentages of 57% and 157 kg meat produced hectare-1 per year. Some enterprises have areas of sown pastures and in those enterprises the carrying capacity increases to slightly more than 1.5 cows ha-1 (FIRA, 1994). Calves are sold to finishing enterprises within the region or to middlemen, culled cows are usually sold for slaughter in nearby towns.
Finishing steers on sown pastures (Cynodon nlemfuensis, Panicum maximum, Brachiaria spp.) in the Humid Tropics is losing importance since the consumer prefers animals finished in feedlots (Ruiz, 2004). Due to the low nutritional value of tropical grasses and low weight gain during “nortes” (between November and February), animals receive supplementary feeding in some enterprises. Daily liveweight gains might be as low as 0.4 kg per animal and the finishing period might last between 18 and 24 months (FIRA, 1994), which jeopardizes the quality of the product. Animals are sold to middlemen; however in Veracruz and Tabasco farmers are organized for selling their product.
Sheep production systems
The remaining goat production takes place under very extensive conditions. Most goats are kept for home consumption of meat of adult animals and occasional milking (mostly for domestic use). Adult animals are sold, but not on a regular basis; in drier areas kids weaned young (two months) are the main product. According to Hernández (2000) and UAS (2004) main attributes of this dominant system are: i) small herds of less than 50 animals, although herds of 1,200 have been noted, ii) feeding is based on grazing and browsing native vegetation and road sides, iii) animals are herded during the day (6 to 10 hours), generally following regular routes and during the night are brought back to very rudimentary shelters, iv) supplementary feeding is rare and only includes maize crop residues and chopped Agave spp., v) males (3 to 10% of the herd) run with the females all year long, vi) no artificial weaning, and high mortality rates of kids, vii) no health measures, viii) lack of specific marketing channels, usually selling to middlemen at very low prices, ix) almost no technical assistance and access to credit, x) variable weaning percentages between 53 and 90%, xi) very low daily liveweight gain, on average 0.05 kg animal-1 with adult weights ranging between 35 and 45 kg, xii) first mating at an age of 12 to 18 months and xiii) milk production between 100 and 140 kg in lactations ranging between 180 and 210 days.