Resource consumption of animal breeding in comparison

As con­su­mers and buy­ers, we are used to full ref­ri­gera­ted coun­ters in Ger­ma­ny: whe­ther beef, pork, poul­try or fish, ever­ything is always avail­ab­le in rough quan­ti­ties. If we now con­si­der how many super­mar­kets the­re are in our area, this con­su­mer offer quick­ly adds up. What con­su­mers often fail to con­si­der, howe­ver, is that enor­mous resour­ces are requi­red for the growth of the ani­mals. Logi­cal­ly, the lar­ger the ani­mal, the more water and feed are nee­ded. But ani­mals – just like humans – do not ful­ly uti­li­ze ever­ything they eat. Due to the incre­a­sing scar­ci­ty of water and the rising pro­te­in requi­re­ments of our rapidly gro­wing world popu­la­ti­on (accord­ing to fore­casts, nine bil­li­on peop­le will live on the earth in 2050), the ques­ti­on ari­ses as to which ani­mal is most effi­ci­ent in the use of natu­ral resour­ces in terms of mee­ting our pro­te­in requirements?

To ans­wer the­se ques­ti­ons, we make a com­pa­ri­son bet­ween fish, poul­try, pork and beef. We inves­ti­ga­te feed con­ver­si­on, water con­sump­ti­on, land use, and the pol­lu­ti­on of ground­wa­ter and air during the pro­duc­tion of one kilo­gram of pro­te­in. We use the con­sump­ti­on data of sea fish from aquacul­tu­re as a basis and refer to the data of other species.

Alt­hough fish live in a lar­ge water body, it has been shown that the freshwa­ter con­sump­ti­on in fish far­ming is signi­fi­cant­ly lower than in other ani­mal hus­bandries. The dif­fe­rence comes from the fact that this balan­ce inclu­des not only the sur­roun­ding or drin­king water but also the water con­sump­ti­on for feed pro­duc­tion. The more feed an ani­mal requi­res, the grea­ter the water consumption.

If you look at the feed requi­re­ment, fish and poul­try are on the same level. Pigs need about twice as much feed as fish and catt­le even four times as much to gain body weight. This is becau­se fish are warm ani­mals. Their body tem­pe­ra­tu­re always cor­re­sponds to the ambi­ent tem­pe­ra­tu­re and they do not need the food to pro­du­ce body heat. All the ener­gy in the food is the­re­fo­re con­ver­ted into bio­mass. Chi­ckens, pigs and catt­le, on the other hand, need part of the feed to main­tain their body tem­pe­ra­tu­re of appro­xi­mate­ly 39°C. The­re­fo­re, they have to take in con­si­der­ab­ly more feed.

In terms of space requi­re­ments for the pro­duc­tion, theo­re­ti­cal­ly more fish than any other ani­mal pro­te­in source can be pro­du­ced in the same space. On the one hand, this is due to the fact that fish are swarm ani­mals and are gene­ral­ly com­for­ta­ble even with high sto­cking den­si­ties. On the other hand, the area requi­red for feed pro­duc­tion must also be inclu­ded in the balan­ce. About 80 % of the world’s agri­cul­tu­ral land is used for fod­der pro­duc­tion and pas­tu­re­land for live­stock bree­ding. This means that land con­sump­ti­on in live­stock far­ming is enor­mous and many times grea­ter than in fish farming.

Other resour­ces that are influ­en­ced by food pro­duc­tion are ground­wa­ter and air. Ground­wa­ter is pol­lu­t­ed when too many ani­mals are kept in a too small space and then more nut­ri­ents are released into the soil through the excre­ments of the ani­mals, i.e. liquid manu­re, which is spread out on the field, than the soil can tole­ra­te in the natu­ral cycle. Due to the incre­a­sed nut­ri­ent con­tent, espe­cial­ly nitro­gen is released from the soil during rain­fall and enters the ground­wa­ter. This pro­cess is also known as „eutro­phi­ca­ti­on“. The air is also pol­lu­t­ed by live­stock far­ming. Bes­i­des CO₂, the metha­ne pro­du­ced by rumi­nants (catt­le) during diges­ti­on is main­ly respon­si­ble for the emis­si­on of cli­ma­te-dama­ging gases. In addi­ti­on, ammo­nia con­tri­bu­tes to the impairment of air qua­li­ty as a result of liquid manu­re fertilization.

In view of the­se figu­res, we can the­re­fo­re clear­ly ans­wer the ques­ti­on of the most effi­ci­ent ani­mal food: fish has the least impact on the envi­ron­ment during pro­duc­tion com­pa­red to all other ani­mal pro­te­in sources. But we should not rest on our lau­rels, becau­se fish far­ming also has envi­ron­ment­al­ly harm­ful and envi­ron­ment­al­ly friend­ly sys­tems (see blog post). Our aim is to make fish far­ming as resour­ce-saving and ani­mal-friend­ly as pos­si­ble. The SEAWATER Cube as a clo­sed recir­cu­la­ting sys­tem ful­fils this claim. With the help of bio­lo­gi­cal and mecha­ni­cal fil­ter sta­ges, more than 99% of the water in the plant is recy­cled, only a small pro­por­ti­on of the resi­du­al sub­s­tan­ces is still dischar­ged as sludge. In addi­ti­on, the fee­ding of the ani­mals is opti­mi­zed, and the con­trol sys­tem ensu­res that only as much is fed as the ani­mals can take in. We have also deter­mi­ned an opti­mal sto­cking den­si­ty for our fish spe­ci­es, at which the ani­mals do not feel stress and do not get sick, and at which pro­duc­tion is as effi­ci­ent as pos­si­ble. Howe­ver, at 65 kg/m³, this is signi­fi­cant­ly below the tole­ra­ble sto­cking den­si­ty of 100 kg/m³ spe­ci­fied in the literature.

Ulti­mate­ly, every con­su­mer should ask hims­elf the ques­ti­on of how much meat he real­ly wants to inclu­de in his nut­ri­ti­on and how the rela­ti­ons­hip bet­ween the various ani­mal spe­ci­es can be chan­ged with respect for the envi­ron­ment. If we were to chan­ge our eating habits and cover a lar­ger pro­por­ti­on of our pro­te­in requi­re­ments with fish in the future, the free agri­cul­tu­ral land could be used to grow rice or pota­toes, for examp­le. This would save valu­able freshwa­ter and at the same time more peop­le could be fed by plants.

Refe­ren­ces:

— Ernäh­rungs- und Land­wirt­schafts­or­ga­ni­sa­ti­on der Ver­ein­ten Natio­nen (FAO) Berich­te von 2006, 2010 und 2012
— Thü­nen Insti­tut für Markt­ana­ly­se, Gerd Hubold und Rai­ner Klep­per, „Die Bedeu­tung von Fische­rei und Aqua­kul­tur für die glo­ba­le Ernäh­rungs­si­che­rung“, Thü­nen Working Paper 3, Braun­schweig, 2013
—  https://www.zeit.de/wirtschaft/2013–08/fleisch-konsum-ressourcen/, 29.09.2018
—  https://www.peta.de/weltwassertag, 07.03.2019
https://mobil.wwf.de/fileadmin/fm-wwf/Publikationen-PDF/wwf_studie_wasserfussabdruck.pdf, 07.03.2019
https://www.welt.de/wissenschaft/article6012574/Ein-Kilo-Rindfleisch-kostet-15–000-Liter-Wasser.html, 07.03.2019
https://www.umweltbundesamt.de/daten/land-forstwirtschaft/beitrag-der-landwirtschaft-zu-den-treibhausgas#textpart‑1, 07.03.2019