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20 October 2014
Författare: Ylva Ran

Thirsty food story: Grasping the invisible ingredient

Every food item we eat needs water for its production, but different foods require different amount of water. What do you think consumes more water: a steak, a glass of milk, a piece of bread or a cucumber? The short answer to this question is that the steak is the biggest water consumer. However, this answer is not enough, it is much more complex than it seems and requires that we understand more of the complexity behind water use in agricultural production.

Regardless of whether you think livestock products is a key ingredient of your every meal or not, it is an important part of human diets globally, especially in low-income countries. 1 billion people in these countries depend on livestock, and it has a significant value for battling malnutrition in many places around the world.

It has already been well established that large scale livestock production systems are very land and water demanding, they are large emitters of methane gas and, when managed badly, pose a threat to water quality and biodiversity. Meanwhile, consumption of livestock products is continuously increasing and the production is expected to double by 2050.

Over-consumption of animal-sourced products has been linked to certain non-communicable diseases, such as cardiovascular diseases, cancer and high blood pressure. It’s likely that reduced animal-sourced food intake could result in lower environmental impact and in better health for some people. However, stopping consumption of animal sourced products is not the solution to environmental and health problems linked to its consumption.

Eating steak, cheese or having milk with your cereal is a personal choice and it should remain so. The question is can resources across livestock supply chains be managed more effectively? Should we feed grains suitable for human food to animals? Can we make a better use of animal’s ability to produce nutrient rich food from non-edible grasses, plant residues and waste?


Is sustainable livestock production possible?

I believe that we have to aim at providing measures and techniques capable of showing clear and real information regarding livestock production, linking up to ecosystem functions and abandoning general quantifications with no spatial connection.

Originating from rainfall, water at the land surface is divided either into run-off, reaching water bodies, or into soil moisture. Generally, livestock production systems allocate over 98% of required water to production of animal feed, both as rain-fed and as irrigation for crops and pasture. The remaining 2% is used for other purposes, such as drinking.
A number of methods have already been developed to quantify the water demand for livestock. The results from these calculations indicate that many livestock production systems demand huge amounts of water. However, these numbers are very general and do not reflect local context or which type of water is used for production.

Why is that?

Firstly, animals can produce edible food from non-edible biomass; for example a cow that produces milk by eating grass. This water used in the production of this grass is still calculated as being consumed in the production of the milk. Even if a cow did not eat the grass, the water would still be consumed for its production. So how do we deal with the “cost” of such water?

Water resource use does not have global impacts like carbon. Water consumption in a water scarce area may have profound effects in that specific location, but that means nothing elsewhere where water is available.

The way water is used matters. Some production systems consume water for irrigation, for example in grain-fed intensive cattle or poultry production. However, as in the case of Uruguayan beef, the most intensive systems require the least amount of water compared to production systems with cows grazing entirely on natural grasslands that are largely water demanding. Without analyzing how irrigation practices are depleting local water bodies, quantification of water demand in both systems will not make it clear which one of them uses water resources more sustainably.

Together with colleagues from the Stockholm Environment Institute, Wageningen University, ILRI and CSIRO I am currently working on a methodology that takes into account the potential of the water resources used for livestock. The method captures if there is an alternative use, for example to cultivate crops instead of animal feed, that would be more suitable at a given location.

The example we are using is Uruguayan beef cattle production. Our results show that the most extensive beef production of the analyzed systems, which feeds cattle only on natural pastures, requires the largest amount of water per kg of produced beef. However, it appears that the land used for pastures in these systems cannot substantially contribute to other human edible food. On the contrary, intensive production systems, where cattle is fed both on pasture and feedlot, the animal feed is produced on a productive land area, able to produce almost 16 times more protein if cultivated with crops that humans would eat directly.

This is an ongoing project, and results are still preliminary. We are developing the method to also include land degradation, as well as other alternate uses of land and water, such as production of fuel and fiber. Furthermore, we need to better understand how the improvement of land, for example by irrigation or the addition of fertilizers, changes the resource potential at a given location.

In the end, we are hoping to provide livestock producers and policy makers with a method that would deliver a picture of livestock water use in its complexity. This way we would be able to make informed choices of resource use and establish a path to sustainable livestock management.

This blog was recognized as a honorable “Runner-up” in the jury voting in the CGIAR’s “Talking Science” blog competition.

Ylva Ran is a Research Associate at Stockholm Environment Institute, her recent work has focused on water resources and environmental impact of livestock production focusing on both global and local impact assessments.

To the CGIAR website