1. Six calves were selected and nursed with milk replacer and calf stater from 7-15 days of age to 3 months of age. Three calves were given formula feeds which contained hydrocarbon grown yeast as a substitution for fish soluble, fish meal and soybean meal; the others were given control feeds.
2. After 3 months of age the calves had been raised in stanchion stalls and another formula feed for raising and fattening had been given, in which one for control and another diet contained hydrocarbon brown yeast for yeast group.
3. Cattle were slaughtered on January 17th, 1973. Average ages were about 483 days old.
4. The results are as follow:
1) There is no any different tendency of growth between the two groups.
2) Available evidence showed that hydrocarbon grown yeast may be substituted for fish meal and soybean meal. For example, average daily gain and feed efficiency were quite similar from 3 months of age to the finishing stage.
3) Carcass characteristics and carcass grades in cattle of the yeast group were a little higher than those of the control group. But it is most probably not significant.
4) The cattle investigated had been in good health throughout the experiment. While No. 4 cattle which had been fed on hydrocarbon grown yeast died at 14 months of age. The cause of death was diagnosed by the office veterinarian as acute bloat, without any connection to the yeast.