Protein supply is a constant challenge for organic farming. Organic raw materials with high protein content are quite scarce in some regions. The search for alternative sources of protein leads to the evaluation of the organic industry by-products.
Brewer’s yeast is a by-product of beer in brewing industries. It is considered a liquid by-product (figure 1) with approximately 15% dry matter (DM). It is obtained from the anaerobic fermentation of beer, formed, among other ingredients, by Saccharomyces cerevisiae. Brewer’s yeast has a high content of protein and vitamins of the B complex, which compensates the high transport costs due to its high water content.
• Yeast has a high content of protein (> 47% DM) of high biological (3.6% of lysine) and digestible value (> 85%), thus reducing the cost of feed.
• Yeast is rich in B vitamins, especially biotin and folic acid (besides vitamin B1, B2, B6, B12, PP, B5) and in vitamin D, with a content of 2000 - 5000 IU /g DM.
• The content of phosphorus in the yeast is up to 0.8-1.3%.
• Yeast promotes animal performance and health.
• Yeast improves the quality of the carcass.
• Two holding tanks are needed for hygiene reasons.
• Yeast deteriorates very easily, do not use the product stored over 2 days.
• It is necessary to deactivate (kill) the yeast before transporting and using it on the farm. Hence, autolyzed yeast should be used.
• Yeast is a quite seasonal product, and it cannot be stored; however, it can be added to silage mixtures as an alternative to avoid its deterioration.