Pigs thrive on protein from clover grass

Experiments carried out at Denmark’s Aarhus University have demonstrated that green protein extracted from clover grass is a very useful diet for pigs. This was the case in terms of pig welfare, growth, feed use as well as meat quality and taste.


ithin the framework of the project SuperGrass- Pork, researchers from the Department of Ani- mal Science at Aarhus University (AU) carried out a feeding experiment with organic pigs,

which were fed compound feed with protein extracted from clover grass. According to a news release on the university’s website, the purpose of the project was to examine the effect achieved when some of the traditional protein – typically soya – was replaced by protein extracted from locally produced clo- ver grass. The experiment involved a dosage-response trial, and the research results demonstrated that the pigs are doing fine with up to 15% grass protein in their feed rations.

Use of protein extracted from clover grass Dr Lene Stødkilde, researcher at the university’s Department of Animal Science, said: “Our results are very positive, as the use of protein extracted from clover grass has huge potential in several areas. Firstly, it will secure the supply of locally grown protein for the growing production of organic pigs in

Denmark; and secondly, the cultivation of grass will increase productivity in the fields and – at the same time – contribute to reducing nitrogen leaching and pesticide use.” The clover grass protein was extracted at a minor biorefining plant at AU Foulum. During the feeding project at AU Foulum, 48 pigs (ranging from the age of six weeks until slaughter) were di- vided into four groups, which were fed three types of feed containing different amounts of grass protein (5%, 10% and 15%) as well as a control group which were fed no clover grass protein.

Growth for experimental compound feeds The results demonstrated that the pigs thrived equally on all types of feeds, as there were no differences in their weight, growth, feed intake and feed utilisation. That meant that feed taste did not affect the pigs’ inclination to eat the feed, and the nutrients were used equally for all feed types. In ad- dition, no health problems were observed for any of the groups during the experiment. Regarding the meat percent- age after slaughter, the results showed that the group of pigs that were fed 15% clover grass protein had a significant- ly higher meat percentage compared to the other groups. “The more grass protein we add, the more optimum amino acid composition we will achieve,” said Dr Stødkilde, adding: “In other words, we cannot rule out the possibility that the pigs in the 15% feed group were fed more digestible protein and more essential amino acids than we aimed for when we composed the feed mixtures. However, this is good news for our feeds, as higher digestibility implies that less grass pro- tein is needed in feed in order to achieve excellent growth and meat percentages.”

The three compound feed mixtures and the control mix- ture (left), in which clover grass protein constitutes an in- creasing proportion of raw protein feed.

More omega-3 fatty acids in the meat The researchers also examined the fatty acid composition of the meat and the results demonstrated that the more clover grass protein added to the feed, the higher the omega-3 fatty acid content of the meat. There was the same percentage of unsaturated fat in all four groups and thus only the relation- ship between omega-3 and omega-6 fatty acids changes in favour of the content of omega-3 fatty acids. The results thus demonstrated that pigs may easily be fed grass protein. Dr Stødkilde said, “It is very positive that we are able to produce ordinary pork based on locally produced grass protein with- out compromising quality and taste.”

▶ ALL ABOUT FEED | Volume 28, No. 3, 2020 9


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