1974 Volume 11 Issue 5 Pages 179-189
Total 711 hens of the third generation in the multi-generation experiment carried out in cooperation of National Institute of Animal Industry and six prefectural experiment stations, half of which were fed the diet containing 15% of yeast grown on n-paraffin continuously from the first generation, were reared until 108 weeks of age and hatchability test with total 3083 eggs of these old hens was conducted.
Hen-housed egg production of the hens on the yeast diet was higher than that on the control diet and the difference was significant statistically. The difference in egg production between the two groups became apparent after the seventh laying period when the hens were about one and a half years of age. Higher egg production reflected as better feed conversion (feed/egg) on the yeast diet, especially after the seventh period.
Daily feed intake was similar between the two groups, and seasonal variation was observed on feed intake. Little difference was also observed between the two groups on average body weight, egg weight and fertility and hatchability measured at age older than 104 weeks.
Viability during 20 to 108 weeks of age was excellent, being 91% in average. No single cause of death was attributable to the yeast feeding. In Gifu Station, 12 hens died of visceral lymphomatosis and mortality of the control group was significantly higher than that of the yeast group.
