Abstract
Performance of the hens and cocks of five generations on either the control diet or the diet containing 15% of one of four kinds of yeast grown on n-paraffin by four domestic manufacturers was combined and analysed statistically. The meat and eggs of the hens of the third generation fed either the control or yeast diet for longer than two years were analyzed chemically for nucleic acids, heavy metals, i, e. Hg, Pb, Cd and As, and polycyclic aromatic compounds such as benzpyrene, which are suspected to be carcinogenic.
Followings were obtained as conclusion of the experiments reported in this and previous papers:
1. Yeast grown on n-paraffin is an excellent source of protein, energy and phosphorus for poultry, except sulphur amino acids and vitamin B12, of which content in yeast is low for poultry feed, resembling the nutritive nature of soybean meal.
2. No evidence is obtained indicating that the yeast contains such a large quantity of toxic substance that the meat and eggs produced by the yeast feeding are injurious to human health. No data are obtained suggesting that the yeast feeding is unfavorable to produce the meat and eggs of good quality.
3. It is suggested that the yeast contains some vital factor or factors which keeps hens on the yeast healthy and productive.
