Water footprint of livestock products and production systems: a review

This paper reviews the small but growing literature on the water footprint (WF) of livestock production and provides an analysis of the strengths, weaknesses, opportunities and threats of this indicator. We identified 42 papers published in peer-reviewed international journals between 2000 and 2017, which covered the WF of dairy, meat and egg production using life-cycle assessment and WF network methodologies. The WF of livestock products decreases with the level of intensification of the farming system. In addition, the WF of meat is higher than that of either milk or eggs. The WF of beef is much larger than the WFs from sheep, goat, pork and chicken. The WF variation among different animal products is explained by the difference of the feed conversion ratio. Ruminants (cattle, sheep and goat) have a poor feed conversion ratio compared with monogastric animals (poultry and swine). Estimating the WF of livestock production and economic analysis of water use at different stages of production will help farmers and other stakeholders to identify the most demanding activities in term of water use, and implement strategies to improve water-use efficiency. Thus, feed production was identified as the largest contributor of the WF of livestock production. Options to reduce the WF of livestock production include the use of low-WF feeds, more efficient irrigation of crops used for livestock feed, and reduced consumption of animal-sourced protein in human diets through substitution with plant proteins. The strengths, weaknesses, opportunities and threats analysis highlighted the importance of combining WF with other environmental-footprint and sustainability indicators to provide more reliable information for decision makers.