Biorefined organic grass-clover protein concentrate for growing pigs: effect on growth performance and meat fatty acid profile

The purpose of the study was to extract protein from organic grass-clover in a biorefining process and report the effects on pig performance and fatty acid profile when including increasing amounts of the protein in feed mixtures. Forty-eight pigs were fed one of four experimental diets from one weak post-weaning to slaughter. The diets consisted of a control diet and diets with 5, 10, or 15% extracted grass-clover protein included. The extracted protein had a crude protein content of 458 g/kg dry matter, a content of total sulphur-containing amino acids comparable to soy press cake, but a lower lysine content. Acid-insoluble residue constituted 215 g/kg dry matter, and the dominating fatty acid was α-linoleic acid. Addition of grass-clover protein extract to the diet did not affect feed intake or growth in starter, grower or finisher pigs and no difference was found in animal slaughter weight. There was a significantly increased meat percentage in animals fed 15 % grass-clover protein extract compared to controls (57.2 % in control vs 60.3% in 15% pigs). Increased addition of grass-clover increased the content of α-linolenic acid in the fat and liver tissue and in the Longissimus dorsi muscle, but also increased the need for antioxidants as demonstrated by a lowered vitamin E content in the meat. In conclusion, the study reports on the composition of protein extracted from organic forages and presents important results from a feeding trial with 48 pigs, where grass-clover protein extract can substitute soybean press cake without adverse effects on performance