The insertion of artificial yolk into the empty oviduct was performed to investigate the shell formation in the fowl.
The insertion of ratificial yolk into the oviduct of hens within 1hr before the expected time of ovulation resulted in a normal deposition of shell. When the insertion was made 1hr and 9-10hr after Ct oviposition of a clutch or 7-8hr after ovulation, all artificial yolks were laid as soft-shelled eggs. However, when estrogen was injected 7-8hr, i.e. 9-10hr after Ct oviposition of a clutch, before the insertion, shell deposited around eggs containing artificial yolk. The effect of estrogen in combination with androgen on shell formation was almost similar to that of estrogen alone and oxytocin seemed to exert no effect on the shell formation.

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An experiment was conducted to measure the effect of individual selection for body weight at 9 weeks of age. After five generations of selection, expected and effective selection differentials as well as response to selection were calculated for male and female chickens, respectively.
The effective selection differential for males which was weighted by the number of progeny, was smaller than the expected selection differential, while these two selection differentials for female chickens were almost identical.
Genetic responses measured by regressing the generation mean divergences of selected line from unselected control line on the cumulative selection differentials, indicated a significant effectiveness of selection for body weight of male and female chickens. Realized heritabilities of male and female chickens which were defined as ratio of genetic respone to selection differential, were 0.224 and 0.363 respectively.
Estimates of heritability for 9 week body weight were computed on within sex-generation basis by intra-class correlation for sib method and intra-sire regression of progeny on dam, and then were pooled over generations. Heritability estimates of female which were estimated from intra-class correlation (sire component) and intra-sire regression of female progeny on dam were in good agreement with realized heritability within their standard errors. However, the estimate of male from intra-class correlation was two times as large as realized heritability. Heritability estimated from intrasire regression of male progeny on dam was smaller than realized heritability of male and was the smallest value of all estimates in this study. The roles of genetic and non-genetic factors on body weight of male and female chickens at 9 weeks of age were discussed.

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More stable linear relationship was observed in the relationship between logarithm of dietary protein level and body weight gain of chicks per 100g feed than that between dietary protein level itself and body weight gain. Based on this finding, gross protein value of casein and a protein mixture of 89.6% soybean meal, 10% fish meal an 0.4% DL-methionine were estimated as slope ratio of two log dose-response lines in 23 experiments, among which linear protein level-response lines were observed only in 6 experiments. A casein-amino acid mixture, composed of 90.9% casein, 5.4%L-arginine•HCl, 1.7% DL-methionine and 2% glycine, was used as standard protein.
Gross protein value of casein was 85 with 95% fiducial interval from 90 to 80. Gross protein values in literature, which were estimated using casein as standard protein, can be changed to new gross protein value based on casein-amino acid mixture as standard protein by multiplying the old value by 0.85.
Gross protein value of the protein mixture was 102 with 95% fiducial interval from 107 to 98. The mixture can be used as auxiliary standard protein.
New standrard procedure to estimate gross protein value is recommended, which is 5-point slope ratio assay, and by which gross protein value can be estimated in 6-day assay with about 540g or less of test protein.

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Duplicated groups of 6 White Leghorn male chicks were fed one of experimental diets containin 0, 3, 6 and 9% of additional standard or test protein to the diet of 11% protein for 6 days. A casein-amino acid mixture was used as standard, and casein and a mixture of soybean meal, fish meal and DL-methionine were tested.
Before and after the experiment, the chicks were sacrificed and their carcass contents of moisture, crude protein, crude fat and gross energy were determined to calculate carcass protein retention per 100g feed eaten. Gross protein value was estimated by 7-point slope ratio assay procedure.
Carcass protein content was almost constant regardless of quality and quantity of protein eaten. With over-lapped fiducial interval, gross protein values from body weight gain and from carcass protein retention were identical from statistical point of view. Error in estimating the value from body weight gain was smaller than that from carcass protein retention.
Body weight of growing chicks in 6-day assay is reasonably accurate index of body protein. Estimation of gross protein value from body weight gain per 100g feed is superior to that from carcass protein retention.

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[in Japanese]

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