The projected increase in water demand by the world's livestock for the year 2025 is 71% and much of this will occur in developing countries (Bruinsmaa, 2003, Delgado et al. 1999).
The relation between water and pig production is an issue that must be addressed immediately and in a systemic approach. Pig production is a constant threat to quantity and quality of water sources. Palhares & Calijuri (2007), water sources are impacted by pig production due the characteristic of theirs wastes that have high concentrations of nutrients.
There are several methodologies for environmental impact assessment. Water footprint is one of them and has been efficient to understand the relationship between natural resources and productions. This methodology can be applied in a nation, city, community, or activity.
The calculation of water footprint to livestock production can be done in several ways. The most common considers water consumed in feed production and for drinking and cleaning (Chapagain & Hoekstra, 2003). Consumption of animals proteins tends to increase the pressure on water sources (Zhang et al., 2008). The result of this process is the increase of water footprint.
The aim of this study was to calculate water footprint of pigs slaughtered in Central-South States of Brazil.
MATERIALS AND METHODS
The study considered the number of pigs slaughtered in Brazil in 2008, according data from Brazilian Geography and Statistics Institute (BGEI). The choice to evaluate the States located in the Central South is justified because these concentrate 98.3% of slaughter in the period.
We used the methodology proposed by Chapagain & Hoekstra (2003) that consider the water consumed in the grain production (corn and soybean), drinking and cleaning waters.
Water consumption to produce one ton of corn in the study region is 4,500 m3/ha. The index used to calculate water consumption to produce one ton of soybean was 6,000 m3/ha. Using the mean productivities for the crops in each State, according data from National Supply Company, we calculated the amount of water consumed to produce corn and soybean.
In soybean production we have three products: grain, soybean meal and oil. Soybean meal is the product consumed by pigs. Therefore, not all water consumed in the production can be counted in water footprint. Using index listed in the Agricultural Commodities Conversion Factors (FAO, 1996), we considered that 77% of production is soybean meal and 23% is oil.
Table 1 shows water consumption for drinking and cleaning in each State.
TABLE 1- Water consumption for drinking and cleaning.
RESULTS AND DISCUSSION
Table 2 shows water footprint of pigs slaughtered by State in 2008. Table 3 the percentage that corn, soybean meal, drinking and cleaning waters represent in the footprint.
The State with the largest water footprint was Rio Grande do Sul (2,702 km3), followed by Santa Catarina (2,401 km3) and Parana (1,089 km3). These States concentrated 70.3% of slaughters in 2008.
States with the lowest footprint were Rio de Janeiro (0.00215 km3), Distrito Federal (0.0354 km3) and Espirito Santo (0.0719 km3). These accounted by 1.1% of the total slaughters in 2008. Although Rio de Janeiro and Espirito Santo presented the worst productivities to corn and soybean, this didn't reflect in a large footprint due the low number of slaughters. Distrito Federal had the best productivity to soybean and the second to corn, but as it represented only 0.5% brazilian slaughters, these high productivities didn't impact the value of footprint.
National mean of water consumption by crops in the footprints calculation was 99.88%. Crops with lower productivities promote high footprints. This demonstrates the importance of improving crops productivities that are basic in pig diets.
The calculations performed in this study showed that the improvement of water productivity in pig production depends on the improvement of corn and soybean productivities. It does not delete actions, programs and policies to reduce the consumption of drinking and cleaning waters in farms. Pig production is highly concentrated in the Brazilian South region, so the consumption to drinking and cleaning will always be a threat to water security in this region.
The majority of water consumption to produce pigs is in the crops rather than consumption for drinking and cleaning. This inserts a change of vision, the water management of pig production can not only happen inside the farm, but it should cover the production chain.
Zoning becomes a important factor in order to regulate the expansion of crops and swines in the territory, as well as subsidizes communities, government and Watershed Committees in decision-making.
This new vision must also consider water consumed in slaughter and products. The difficulty in calculate these intakes is the lack of information to Brazilian reality.
TABLE 2 - Water footprint of pigs slaughtered in 2008 by State.
TABLE 3 - Percentage of corn, soybean meal, and drinking and cleaning waters in the footprint.
We concluded that:
1. Low productivities to corn and soybean increase the value of footprints. States with the biggest herds must improve their productivities in order to reduce the footprint;
2. In the footprint values, water consumed for corn production was the largest amount. The water used to drinking and cleaning were insignificant in the value, but should be considered because animal concentration in the territory;
3. Footprint shows that water management in pig production can not consider only the farm, but shall include the production chain;
4. Zoning areas with high concentration of pig production will promote water security, help to understanding waters flows, and improving water productivity in pig chain.
Researches from Embrapa Maize and Sorghum, Ricardo Brito and Camillus de Lellis T. de Andrade and researcher from Embrapa Soybean, José Renato, because information about consumption of water by corn and soybean. Researcher from Embrapa Swine and Poultry, Gustavo J. M. M. Lima, that gave information about diets.
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