Nutritional Value of Spent Brewers’ Yeast (Saccharomyces cerevisiae): A Potential Replacement for Soya Bean in Poultry Feed Formulation

Abstract

The increase in the world population results in a rising protein demand which becomes the most important factor in accelerating the development of the poultry industry. Poultry requires nutrients such as protein, fat, carbohydrate, vitamins and minerals for growth and development. Protein source within the poultry feed contributes to the major cost in the fish industry. Thus, an evaluation of single cell protein, the spent brewer’s yeast (Sacchamormyces cereviciae) as a feed material was carried out to determine its potential application in poultry feed formulation. Methods: Spent brewers’ yeast (Saccharomyces cereviciae) was inactivated by boiling and then machine dried analysis analysed for nutritional value. Results: The crude protein was 40.52% dry basis with crude fibre of 4.31% also on dry basis. It had a metabolizable energy of 2606.07 kcal/kg. The amino acid analysis showed that both essential and non-essential amino acids were present. The essential amino acids included leucine (8.42%), valine (6.07%), threonine (5.65%), isoleucine (5.37%), phenylalanine (5.30%), arginine (4.74%) histidine (2.93%), lysine (2.93%) and tyrosine (2.73%). Non-essential amino acids included glutamic acid (14.98%), aspartic acid (11.98%), alanine (7.26%), serine (5.75%), proline (4.84%) and glycine (4.83%). Cystic acid, methionine and tryptophan were absent. Conclusion: These results showed that the spent brewers’ yeast had nutritional value and can be used to formulate animal feeds such as poultry feeds as protein source to replace soya bean. However, methionine and tryptophan would have to be supplemented.