Epidemiological studies of coccidiosis were conducted in Japanese quail (Coturnix coturnix japonica) farms for 3 years.
The following results were obtained on 2, 630 quail groups in 56 quail farms during the period from July 1, 1969 to June end of 1972.
1) Eimeria was detected in 96.6% of the quail groups.
2) The intensity of the infection appeared independent on season factor.
3) The regional defferences of quail farms in term of Eimeria infection was not observed.
4) The lower viability of quail chicks in the farms, the higher OPG values were observed, and a correlation was found between the viability and the OPG values (γ=-0.504).
5) The egg production was also reduced by 18.9% following artificial infection with Eimeria at a dose of 2.88×10⁵ per bird.

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In a series of studies on the variations in the feeding activity of chickens, an experiment was conducted to determine the effect of the physical form of feed on the diurnal changes in this feeding activity.
Eight Single Comb White Leghorn hens were reared in individual cages under a 14-hour light-day, and given five different forms of feeds including various type of mash, pellets and crumbles.
Diurnal changes in feeding activity were determined with individual birds which received each of the experimental feeds by the use of an apparatus that provided a continuous record of the changes in feed intake and the time spent eating.
Although daily feed intake was not appreciably affected by any of the forms of feed, there was clear evidence that the time spent eating was decreased by granulation of the feed. It was observed that the birds receiving mash were at the feed trough almost continuously during light hours while the birds receiving pellets were at the feed trough very intermittently and consumed a considerable amount of feed in an appreciably shorter period of pecking.
When the birds received the ordinary type of commercial mash ration there was a marked trend for the feeding activity to be increased initially after offering fresh mash. This temporary increase in the activity entirely disappeared when the birds received pellets or reground mash ration in which the particle size of the feed was made uniform.
Feeding activity, irrespective of the form of feed offered, was found to occur intensively during the hours of light, but tended to decrease in the early morning. Further, when birds received pellets a marked decrease in activity was observed during the middle period of the hours of light.
It seems apparent from these results that the physical form of feed, particularly the particle size of feed, is an important factor capable of regulating the rate of eating and the intervals of ingestion of feed within a day under condition of ad libitum feeding.

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High incidence of perosis was observed repeatedly on meat-type chicks fed low protein-high energy experimental diet in this laboratory. Results of three experiments to find out dietary factor or factors related to the appearance of perosis were summarized as follows:
Nicotinic acid, biotin, vitamin B₁₂, phosphorus, zinc and magnesium supplemented to the perotic diet, which contained enough choline, folic acid and manganese, had little effect to prevent perosis.
Perosis was observed not only on the meat-type chicks fed the semi-purified low protein-high energy diet but also on those fed the diet containing common feed ingredients, such as yellow corn.
Decrease in dietary energy by adding cellulose in the perotic diet was effective to prevent perosis. Though increase in dietary protein level was effective to prevent perosis, chicks on the higher protein diet showed the symptoms of perosis if dietary energy level increased further. Therefore, it was suspected that high level of dietary energy, rather than dietary protein itself, has direct influence on the appearance of perosis.
Incidence of perosis of White Leghorn chicks on the perotic diet was significantly lower than that of meat-type chicks, suggesting the breed difference of susceptibility to the perotic diet. Little difference was observed on the incidence of perosis between males and females.
No difference was observed between the symptoms of perosis of the chicks on the high energy perotic diet and on the diet deficient in manganese. However, body fat deposition and plasma alkaline phosphatase activity of the chicks on the high energy perotic diet were significantly higher than those of the chicks on the manganese deficient diet and on the control diet. Therefore, biochemical mechanism of perosis on the high energy diet is suspected to be different with that of manganese deficiency.

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Collaborative expriments were carried out with National Institute of Animal Industry and 6 Prefectural Experiment and Breeding Stations on the effect of hydrocarbon yeast grown on n-paraffin on reproducibility of breeding hens. In each station, about 200 female and 30 male one-day-old White Leghorn chicks were divided into equal two groups. Control diet was fed to a group and yeast diet containing 15% of one of 4 yeasts produced by 4 companies in this country was fed to the other. Mating females and males on the same diet, chicks of the second generation were obtained and reared similarly by feeding the same diet as fed to their parents. Chicks of the third generation were obtained and reared under the same experimental plan.
Chicks of the first generation were reared for 52 weeks, during which 3 hatchability tests were carried out. After 52 weeks of age, 10 hens each from each of 2 groups per Station, i.e. 120 hens in total, were sacrificed for histo-pathological examination. Chicks of the second and third generations were reared for 44 and 36 weeks, respectively, with 2 and 1 hatchability tests, respectively.
Summarizing the data of 3 generations with total 4, 318 chicks and 6 hatchability tests with 40, 592 eggs, following conclusions were obtained:
1) Little difference was observed on egg production, feed intake and feed conversion during laying period, average egg weight and body weight at 36 weeks of age between two groups fed either control or yeast diets.
2) Fertility and hatchability of fertile eggs on the yeast diet was slightly higher than those on the control diet, though the difference was not significant statistically. All of the chicks hatched were healthy and no deformity was observed. Little difference was found on mortality of the chicks until 20 weeks of age.
3) Viability of hens on the yeast diet was slightly but significantly (P<0.05) higher than that on the control diet.
4) Growth rate of the chicks on the yeast diet was significantly (P<0.01) slower than that on the control diet. Sexual maturity of the chicks on the yeast diet was 3 days later (P<0.05) than that on the control diet. One of the reasons of these differences was suspected to be due to the difference in energy and protein levels between the two experimental diets.

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As the first step to modify the procedure for the determination of gross protein value, three experiments were carried out to get optimum composition of the standard casein-amino acid mixture and an experiment was conducted to determine metabolizable energy of the casein-amino acid mixture.
A casein-amino acid mixture, composed of 90.9% of casein, 5.4% of L-arginine•HCl, 1.7% of DL-methionine and 2% of glycine, was found suitable as a standard mixture under the sub-optimum dietary protein level of 18%. The chicks showed little growth response on further supplementation of glycine and L-tryptophan. Further supplementation of DL-methionine and decrease in the ratio of essential and non-essential amino acids by supplementing L-glutamic acid depressed the response of the chicks.
The protein mixture, which was composed of 89.6% of soybean meal, 10% of fish meal and 0.4% of DL-methionine, and which has been used as the reference protein mixture in this laboratory, had almost identical protein value to that of the casein-amino acid mixture. Thus, the protein mixture of much cheaper price than the casein-amino acid mixture can be used as secondary standard after its protein value is determined exactly.
The protein mixture can be used as a sole protein source in the basel diet.
Metabolizable energy of the casein-amino acid mixture and the protein mixture was 3.90 and 2.31kcal/g, respectively.

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LUSH (1947) discussed the accuracy of combined selection relative to that of mass selection on the assumption that the value of full-sib resemblance (intra-class correlation) used for calculating weights to be given to individual's own phenotype and family average perfectly agrees with the actual value of it in the population to which combined selection is applied. This assumption, however, could not be strictly real in most cases.
In the present note, a formula for the relative accuracy of combined selection, in which both the assumed and actual values of full-sib resemblance can vary, was derived to examine to what extent the relative accuracy of combined selection is lowered by discrepancy between such two kinds of values. Numerical examples were given for the cases of family size being four and eight.
General conclusions are: 1) As far as the actual value of full-sib resemblance (τ) is around 0.3 or less, combined selection is never less accurate than mass selection, whatever value between 0 and 0.5 may be used as the assumed value (t). 2) Combined selection may become less accurate than mass selection when τ is about 0.3 or larger and t is smaller than 0.3, depending upon the amount of discrepancy between τ and t. 3) At a given level of τ between 0.1 and 0.4, discrepancy of the order of 0.1 in either direction between τ and t lowers accuracy of combined selection only by around 2 per cent compared to the maximum accuracy expected when t equals τ.

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