No abstract

No abstract

No abstract

No abstract

A four-year project of collaborative experiments has been carred out to study the effect of four kinds of yeast grown on n-paraffin in four domestic manufacturers, which are called just yeast in this paper, on reproducibility of breeding hens and at the same time to get information whether the yeast has any factor or factors undesirable for health of the hens themselves as well as of their offspring and for human health possibly through eggs and meat produced on yeast. For this purpose, successive six generations of White Leghorn hens were raised in six Prefectural Poultry Experiment Stations either on the control diet or on the diet containing 15% of yeast.As reported already1,2), two groups of 100 hens each of the first through the third generations, divided into five lots of 20 hens each, were reared on either the control or the yeast diets in each of the stations.The hens of the first generation were sacrificed for histopathological examination after 52 weeks of age. Although no significant change due to the yeast feeding was observed histopathologically, it was pointed out that one year of age is too young to check the possible histopathological change due to the yeast feeding.Accordingly, 60% of the hens of the third generation, i.e. three lots each on each of the diets in each of the stations, were decided at 36 weeks of age to be reared further until more than two years of age. Hens of the fourth and the fifth generation were reared using the rest of the feeding facility, i.e. 40 hens in two lots on each of the diets in each of the stations, were reared.Performance of the hens of the first generation1) and of the second and the third generations2) were already reported. In this paper, performance of the hens of the fourth through the sixth generations are presented.