Water use on Irish pig farms, a good news story
Irish systems perform well when it comes to minimising use of freshwater resources
Pork production contributes 19% to the global water footprint (WFP). The WFP of pork is calculated by considering the volume of freshwater used per unit of product produced (usually m3/ton). This total WFP is divided into green (i.e. rain water used in crop production), blue (e.g. irrigation and drinking water) and grey water (i.e. waste water).
The WATERWORKS project, which is drawing to a close, calculated the direct on-farm and off-farm green and blue water use of Irish pork production systems, to enable us to identify farm specific improvement options to reduce freshwater use, and compare the WFP of Irish pork production relative to other countries.
Experimental set-up
Twelve Irish commercial pig farms took part in the study with the support of their Specialised Pig Advisor. We installed water meters on each farm for each production stage, in the cleaning lines, and where relevant if feed was mixed on the farm, and collected water and production data for one full year. We obtained diet specs for each stage and feed usage per stage so that we could quantify the freshwater use that was required for cultivation of crops for feed. The WFP of each farm was calculated by adding the total feed water use (L/year) to the metered on-farm blue water use (L/year) and dividing by the total amount of pork produced (kg) (i.e. carcass weight) on the farm during the year.
On farm water footprint
The on-farm WFP consisted of blue water only, and included drinking water, feed-mixing water and washing water. It ranged from 8.0 to 29.4 L/kg pork (average; 14.1 L/kg pork) and was 70% of the total blue WFP, with the remaining off-farm and used for the production of feed. Overall, the major contribution towards on-farm BWFP was from drinking, followed by feed mixing and washing water. For dry feed farms, drinking water was the main contributor, and for wet, and wet and dry feed farms, feed mixing is the major part of on-farm blue water use.
Among all the production stages the finisher stage (65%) contributed most to drinking water use, followed by the weaner (19%), gestation (10%) and lactation (7%). This implies that to minimise the blue water use on the farm, the finishing stage can act as a crucial starting point, with a focus on strategies to reduce water wastage.
In a separate experiment as part of the larger WATERWORKS project, we found that providing pigs with supplementary environmental enrichment in the finishing stage, with the aim of distracting pigs’ attention away from the drinkers, significantly reduced water use.
Off farm water footprint
The off-farm WFP consisted of both green and blue water use for the production of pig feed. The average WFP for feed production was 2,523 ± 233 L/kg pork with a range of 2,006 to 2,894 L/kg pork. This included mainly green water. As well as feed origin and dietary composition, green water use is mainly affected by feed use efficiency, as pigs that are more efficient will use less feed, and hence water.
Overall, off-farm water used for feed production (99.4%) was the major component of total WFP, and of this, green water was by far the most important contributor. Thus, factors such as feed efficiency, feed composition and ingredient origin have a major influence. Choosing sustainable feed ingredients such as inedible by-products or locally sourced feed to reduce pressure on the water resources of other countries is a decision which many pig farmers in Ireland could take, since about 43% of the Irish pig farmers are home millers.
Total water footprint & international comparison
The on and off farm WFP need to be considered together to get an overall view of freshwater use. We found that this was an average of 2,537 L/kg pork. Over all farms, the difference between the most efficient and least quartile of farms was 7% of the total WFP, indicating relatively uniform use of water across all farm types.
Our findings are in line with the majority of studies from other countries which found a WFP ranging from 2,800 to 4,500 L/kg pork, with green water making up 80 to 99% of the total. Compared to these studies the total WFP of Irish pig farms was at the low end (2,537 L). This could be due to improved pig performance in the past 20 years. Some of the improvements in performance in Irish pork production systems between 2000-2020 include a 30% increase in piglets born alive per litter, an increase in carcass deadweight of 20.1 kg per pig, improved average daily gain from weaning to sale of 150 g per day and a decrease in the amount of feed required from 3.66 to 3.50 kg of feed to produce a kilogram of pork.
Conclusion
This study presents the first WFP assessment of Irish pig farms using farm specific data, and is a novel research as this level of detail for pig production did not exist before this study. Because the overall WFP of Irish pig farms was at the low end of previously published studies, Irish systems appear to perform well when it comes to minimising use of freshwater resources. This reflects well on current Irish pork production systems, relative to those elsewhere. Nevertheless, this study also indicates an opportunity to adjust management strategies, and source either by-products or feed ingredients from non-water stressed areas, to further reduce the burden on freshwater resources.
Keelin O’Driscoll, Amy Quinn, John Upton & Shilpi Misra
Read the Teaagsc PIg Newsletter May 2023