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Putting grass protein to the test

A group of researchers is currently examining whether it will be possible to replace traditional protein sources with protein from clover grass in organic pig feed. They are rather optimistic.

[Translate to English:] Grisene i forsøget æder en af fire forskellige blandinger, hvor indholdet af græsprotein varierer. Jo mørkere farve, des højere er indholdet af græs.
[Translate to English:] Grisene i forsøget æder en af fire forskellige blandinger, hvor indholdet af græsprotein varierer. Jo mørkere farve, des højere er indholdet af græs.

At the moment, the organic animal science platform at Aarhus University, Foulum, is the centre of attention. A herd of lively pigs has moved into the facility. They are part of a major project – the culmination of several years’ efforts.

The pigs are fed a diet in which part of the protein comes from clover grass – and not traditional protein sources like soya.

- We want to demonstrate that it is possible to replace part of the imported soya used in standard compound feeds with grass protein. We succeeded in completely removing soya from our 15 percent compound feed. This feed only contains Danish raw materials, says Researcher Lene Stødkilde-Jørgensen, Department of Animal Science, Aarhus University.

In her hand, she is holding a small container with a green powder. This powder is the result of many years of research. The clover grass used to make the powder is grown in the fields in Foulum. For many years, researchers have contributed efforts to the cultivation and management of green biomasses – and it turns out that the cultivation of grass increases productivity in the fields, as well as contributes to reducing nitrogen loss or leaching from the fields. It seems possible to kill two birds with one stone.

The pigs eat well and thrive

The actual process of extracting the protein from the grass requires a significant amount of time. It takes place at the biorefinery plant in Foulum, and currently an even bigger plant for grass protein production is under construction. Besides protein, the green crops also contain a fibre fraction that may be used as cattle feed or as raw material in biogas or ethanol production.

The experiment was initiated in November, when the pigs  were weaned. Since then, they have been fed one of four compound feeds, each with varying contents of grass protein. They will be fed until slaughter in March.

-  All four compound feeds have been composed to satisfy the pigs’ needs. However, even though we may – theoretically – have excellent feeds with all the right nutrients, we still have to examine if the pigs grow as well as we expect them to. And the first step is to see if they want to eat the feed. Grass protein has a very strong taste of grass, says Lene Stødkilde-Jørgensen.

Two months into the study, the researchers are optimistic:

- We notice that all four groups of pigs thrive very well; they eat well and seem in good health.

The importance of grass to meat colour, taste and structure

In addition, the researchers need to examine the importance of grass protein in relation to taste, colour and structure as well as the contents of fatty acids and vitamins in the meat and lard. Previous studies in chickens demonstrated a connection between high contents of unsaturated fatty acids and vitamins in clover grass protein and the corresponding content in chicken meat.

Speaking in terms of nutrition, this will result in an improved fatty acid composition with an increased content of omega-3 fatty acids. On the other hand, it may also be important to the shelf life of the meat.

-  We have to study this in more detail, as consumers expect products that are similar to those they usually buy. We will carry out a series of analyses, and expect to provide some answers in 2019, says Lene Stødkilde-Jørgensen.

Further information

The project SuperGrassPork is part of the Organic RDD 3 programme, which is coordinated by ICROFS (International Centre for Research in Organic Food systems). It is funded by the Green Development and Demonstration Programme under the Ministry of Environment and Food.   

Project partners: SEGES; Department of Animal Science, Department of Engineering and Department of Agroecology, Aarhus University; Department of Chemistry and Bioscience, Aalborg University; Institute for Food Studies & Agro industrial Development Aps (IFAU); Department of Food and Resource Economics, Copenhagen University; Friland A/S and Vestjyllands Andel A.m.b.a.

Want to know more about green protein? Visit Centre for Circular Bioeconomy

Researcher Lene Stødkilde-Jørgensen
Department of Animal Science, Aarhus University
Email: lsj@anis.au.dk
Phone: +45 8715 4284

Project coordinator, Erik Fog
Email: erf@seges.dk
Phone: +45 8740 5490