Determinant factors of economic performance of goat meat production systems in arid rangelands of Mendoza, Argentina
The total world goat population in 2014 was estimated at 1,008 million and included a total of 570 breeds (FAO, 2014). Goats are distributed across all regions and ecosystems of the world, but arid environments are favored. Meat production is the principal function of goats throughout the developing countries. Generally low level of production in these countries is associated with inefficient feeding and management, inadequate use of the indigenous goat genetic resources, and disease constraints (Devendra, 2010). Goats play an important role for the provision of animal protein and as source of income to small holders in marginal rural areas of the world (Castel et al., 2010; Devendra, 2010; Mahgoub, 1997).
The existence of goats in Argentina was 4.2 million in 2011 (MAGYP, 2010). In Mendoza province there are more than 800,000 goats and 3,500 producers who engage in this activity (MATM, 2012).
The prevailing production system is that called "rangeland-based system", found in the semiarid and arid regions of the world, where sparse vegetation, containing mainly native grasses and shrubs, is characteristic in these regions. These plants are important source of feed (Devendra, 2010).
Goats are the predominant livestock species in the rangelands of northeastern Mendoza plain (Guevara, 1991). In 2002, this area of 10,244 km2 had 96,750 goats, which represented 14.4% of the Mendoza goat herd (Bernard, 2007). Goat production is undertaken by 608 small stockmen (PlaNet Finance, 2011). Goats have been traditionally kept for meat production.
The most extensive feeding system is continuous grazing without fencing, which is the most practical way for exploiting the natural vegetation; goats are herder or are free roaming to graze what they can find (Allegretti et al., 2012). The stockman, who lives in the production site, provides all or most of the necessary labor. The cultural and socioeconomic conditions of the inhabitants and their limited access to improved technology have led to overgrazing and its consequent impact on vegetation, soil and future productivity. Goat herders generally occupy communally or state-owned land (Guevara et al., 2009). In general, goat production is associated with the activity of many subsistence farming families when natural resources do not permit to generate other profitable economic activity (MATM, 2012). As occurred in other areas of the world (Zaibet et al., 2004) generally there is no record keeping or selection programs in the study site except for a natural selection towards survival more than production.
To our knowledge, there were not studies related to the estimation of production functions for meat goat production systems in Argentina. In other areas of the world, the studies of production functions are referred to dairy goats (Kipserem et al., 2011), livestock milk (cattle, sheep, goats, camel and horses) in Pakistan (Ishaq et al., 2007) or the characterization of dairy goat production systems using ANOVA (Capote et al., 2006). Cobb-Douglas function and other models were used to investigate technical efficiency of goat producers in the Sultanate of Oman (Zaibet et al., 2004).
The purpose of this study was to identify the variables that affect the annual income of meat goat production systems and quantify their relevance. It was hypothesized that the number of kids produced annually is the main variable that influences the economic performance of production systems.
Material and Methods
Most of the study area is comprised by a desert of dunes (Roig et al., 1992). Saline depressions are present along the eastern border of the area (Guevara et al., 1997). The vegetation is typical of the Monte phytogeographic province (Roig et al., 1992). Shrublands and open woodlands play an important role because they provide forage for grazing animal throughout the year. Vegetation communities of major foraging importance with regard to floristic composition, forage species cover and carrying capacity are: a) semi-closed woodlands of Prosopis flexuosa DC. (algarrobo dulce) with Atriplex lampa Gillies ex Moq. (zampa) in interdune valleys, and b) open woodlands of P. flexuosa with A. lampa and Tricomaria usillo Hook. & Arn. (usillo) on dunes (Alvarez et al., 2006; Passera et al., 2004).
Mean annual rainfall in the area is 175 mm (S.D.= 77.4) (Guevara et al., 1996), most of which falls during the spring-summer period. The bioclimatic conditions are considered "warm-arid" with a mean annual temperature of 20[grados]C. The precipitation/potential evapotranspiration (Penman standard) ratio is about 0.08 (Guevara et al., 2006). Soils are mainly sandy with undifferentiated horizons (Entisols and Aridisols). Estimated rangeland carrying capacity was 45.5 ha [cow.sup.-1] or 7.3 ha [goat.sup.-1] (Guevara et al., 1996).
Animals and production systems
The "Criollo" goats, the most common breed in the study area, descended from goat breeds transported by the Spanish and Portuguese colonizers from the Canary Islands (Amills et al., 2009). Goat parturition occurs in two periods of the year: spring-summer (November-December) and fall-winter (May-July). About 70% of goats kid in the latter period, in which there is no kid...