The present authors isolated Bacillus, Escherichea, Klebsiella, Rettgerella and Enterobacter from baby chicks which had died from omphalitis. Omphalitis was reproduced only with the Bacillus, which was identified as B. cereus, and named 0-114 strain. Experimental baby chicks were inoculated with this organism into the yolk sac, intraperitoneously, subcutaneously or orally. Omphalitis was reproduced only when inoculated into the yolk sac. Inoculation of the spores of this organism into the yolk sac also gave results similar to those obtained by inoculation of the vegetative form. Omphalitis was also produced by inoculation of organisms inside the egg shell of pipped eggs.
From these results, B. cereus seems to be responsible for the development of omphalitis in baby chicks.

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Count of the numbdr of bacteria in the air of the incubator, isolation of bacteria from dead in shell chicks, pipped eggs, dead baby chicks and mushy baby chicks, and inoculation of the isolated bacteria into the egg yolk of baby chicks led to the following conclusions:
1. The microbial flora in the air of the incubator consists mainly of Bacillus Spp. predominately B. cereus.
2. B. cereus is the most frequently incriminated causative agent of omphalitis.
3. Bacillus in the air of the incubator enter into pipped eggs and multiply in the egg shell cavity. Further, wheen the closing of navel of the germ in incomplete, is may invade the egg yolk via the navel, and multiply there, resulting in omphalitis in those baby chicks.
4. In omphalitis due to Bacillus, pipped egg and baby chick frequently die following an acute disease course. However, some of these follow a chronic course instead and become mushy baby chicks.
5. To prevent omphalitis, removal of the offending Bacillus from the incubator must be accomplished.

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Two tests were consecutively conducted using spring-hatched White Leghorn males to examine if semen production could be improved by keeping male chickens under long daylength throughout the year.
In the first test, 24 males reared in natural daylight were divided into two groups; one received an increasing daylength for the first 8 weeks and then 14 to 15 hours of daily light to the end of the test, the other received natural daylight alone. The test began in November 1966 and ran for 56 weeks. Semen samples were examined weekly for the semen characteristics, and fertilizing capacity was determined monthly by artificial insemination.
In the second test, each half of the males of the groups used in the first test were exchanged between the previous treatments, and one group received 15 hours of light, the other received natural daylight alone. The semen characteristics were examined for 20 weeks from December 1967 to April 1968.
The results were as follows:
1. Males supplied with extra light showed an improvement in semen characteristics and fertility, and seasonal decline was reduced. Adverse effect of supplementary light was not observed.
2. Semen production during the cold season seemed to be much affected by daylength, but not by ambiant temperature.
3. Correlations between fertility and semen characteristics were comparatively low in the males supplied with extra light.
4. It is suggested that control of photoperiod length with artificial light is effective on semen production, and that semen production in its declining season can be improved by keeping male chickens on a 14 or 15 photoperiod.

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Collaborative experiments at 6 Prefectural Poultry Experiment Station with 1, 444 White Plymouth Rock pullets were carried out to study the effect of regulation of body weight by restricting the daily supply of feed. Feed supply was so restricted that body weight of pullets at 24 weeks of age was either 80, 70 or 60% of that of control pullets fed ad libitum in each Experiment Station. After 24 weeks of age, all the pullets were fed the layer diet full.
1. Pullets kept their body weight at 80% level started to lay almost simultaneously and with similar egg weight to the control pullets. In average, they produced hatching egg at the rate of 5.6% higher with 1.5yen/egg less feed cost than those of the control did.
2. Pullets kept their body weight at 70% level delayed in sexual maturity by 5 days and layed a significantly heavier first egg. The production of hatching egg was 9.7% higher and feed cost per hatching egg was 2.0 yen lower then those of the control, the difference being significant at 1 and 5% levels, respectively.
3. Pullets kept their body weight at 60% level delayed in sexual maturity by 16 days and layed a significantly heavier first egg. The production of hatching egg was 7.3% higher and feed cost per hatching egg was 3.8 yen lower than those of the control, the difference being significant at 5 and 1% levels, respectively.
4. Summarizing all of the data, it was suggested that body weight at 24 weeks of age should be kept at the level less than 70% of the control to get better performance in laying period.
Little effect on mortality of the pullet was observed among the different feeding programs.

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The effect of steroid hormones on the staining intensity of Es-1 region of the zymogram of chicken plasma alpha-naphtyl butyrate esterases was investigated. The Es-1 region is the most anodally migrating region and it's types are found to be controlled genetically (KIMURA, 1969). The staining intensity of this region of laying hens is usually too weak to determine the Es-1 phenotypes.
Intramuscular injections of estradiol benzoate to cocks resulted in a diminished staining intensity of the Es-1 region. Progesterone and testosterone enhanced the intensity. After the injection of these two hormones to laying hens with a daily dose of 1mg. per kg. of body weight for five days, the Es-1 region showed a strong staining intensity which is comparable to that obtained in cock's, while egg laying were not affected by these injections.

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Thirteen experiments were conducted to study age difference in the requirement of sulfur amino acids for 2 meat-type chicks, i.e. White Cornish × White Plymouth Rock and White Cornish × New Hampshire, and a egg-type chicks, i.e. White Leghorn. Graded Levels of DL-methionine were added to corn-soy or cornstarch-soy basal diets, of which cystine and methionine levels were adjusted based on the determination of these amino acids by an amino acid analyzer. Requirement of sulfer amino acids were estimated based on body weight gain and feed efficiency of the chicks.
Requirement of sufur amino acids for chicks younger than 3 weeks of age was confirmed to be 0.66% in the diet containing 20% of crude protein, while that for chicks older than 4 weeks was 0.57% in the diet containing 16% of crude drotein. No difference in the requirement among the breeds tested was observed.
It was confirmed that after 4 weeks of age, dietary sulfur amino acids could be reduced to such a level, on which growth rate of younger chicks was retarded. When adequate sulfur amino acids level was shown as per cent of dietary crude protein, that was 3.3 and 3.6 per cent of crude protein, for younger and older chicks than 4 weeks of age, respectively.

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From the results of previous experiment, authors suggested that there was possibility of making higher density of the laying cage house than that common in Japan. This study conducted to obtain the informations of the housing density of the laying cage house. Nine hundred commercial birds Babcock B 300 at 125 days of age were put into the cage. Two laying cage house, 4m width, 20m depth and 3.5m height were used. Cage size used in both houses was 24cm width, 39cm depth and 40cm height. In high density house, two birds were put into one cage, in another ordinary density house, one bird in one cage. Number of birds per square meter of laying cage house were 7.5 in high and 3.75 birds in ordinary density house. Experiment was conducted over the one year from 126 to 500 days of age.
There were no differences in days to 50% egg production, percent of egg production hen day basis, number of egg laid of survival birds, egg weight, feed consumption, feed conversion and viability between laying cage houses. The performances of layer in high density house did not decreased comparing with the birds in ordinary density house. The time required of daily management of the birds in high density house was about 1.5 times as long as ordinary house but the time required in high density per bird was shorter than that in ordinary density house.

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