A Short-Time Chick Assay for Unidentified Growth Factors

IT HAS been reported by many investigators that growth of chicks is improved by the presence of unidentified growth factors in fish meal, fish solubles, green feed, and corn fermentation products when these are added to the practical diets. After the availability of crystalline vitamin B12, the presence of another unidentified growth factor was first reported by Carlson et al. (1949) using a purified diet. The same observations were also reported by Sunde et al. (1950) in a diet of commercial feedstuffs. Camp et al. (1955) reported one factor in fish solubles and another in whey products which are responsible for a better growth response. Barnett and Bird (1956) developed a standard four-week chick assay to determine the unidentified growth factor activity of crude materials. This assay with slight modifications has been extensively used to measure the unidentified growth factor activity of many samples of fish meal and fish solubles.