Compared with the control chicks, the chicks fed ad libitum with the arginine-deficient diet consumed less feed and less metabolizable energy, and subsequently, gained less weight and less energy, and showed lower gross energetic efficiency. When the same amounts of the control and arginine-deficient diets were tube-fed, the arginine-deficient chicks gained less body weight and retained less protein energy and more fat energy than the control chicks. Total energy retention was not affected by arginine deficiency and was simply proportional to the ME intake. Arginine deficiency affected neither the maintenance ME requirement nor the net efficiency of ME utilization for energy gain. These results show that the decreased energy retention in the chicks fed ad libitum the arginine-deficient diet is associated with the decreased feed intake.Acknowledgement The authors wish to express their thanks to Mr. H. SAITO for his technical assistance.

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Arginine vasotocin (AVT), prostaglandin E₂ (PGE₂) and prostaglandin F_2α (PGF_2α) in-duced premature oviposition when injected 1-4h (hard-shell egg in uterus) and 15-19h (soft-shell egg in uterus) before the expected laying time.These drugs were more effective in inducing oviposition when a hard-shell egg was in the uterus than when a soft-shell egg was in the uterus. AVT caused an increase in im-munoreactive PGE2 production when incubated with uterine homogenate.The present results suggest that the sensitivity of the hen uterus to AVT, PGE₂ and PGF_2α increases as the time of oviposition approaches and that AVT acts through the enhan cement of immunoreactive PGE₂ production in the uterine tissue of hens.

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The concentrations of sex steroids in plasma from 2 weeks before the onset to the end of incubation was determined comparing the nesting frequency in Gifujidori hens. The nesting frequency increased progressively from 5 days before the onset of incubation (hen spending more than 90% a day on the nest) and the hens only left less than 2h a day dur-ing the incubation period. Inversely, food and water intake began to decrease from 2 days before the onset of incubation and the mean intake during incubation was 18.8±1.2g of food and 21.9±2.1ml of water. The concentrations of sex steroids began to decrease from 4 days before the onset of incubation reaching basal line levels on the first day in proges-terone, but testosterone and estradiol took an additional one to two days. Significant nega-tive relationships were observed between the nesting frequency and the three sex steriods concentrations. During the incubation, the mean concentrations varied between 55±11 and 103±31pg/ml in progesterone, 60±12 and 124±27pg/ml in testosterone and 29±3 and 55± 16pg/ml in estradiol. The decremental ratio of the plasma concentrations of sex steroids in incubating hens for that of laying hens was progesterone (60%)>estradiol(50%)>testosterone (40%). A significant (p<0.01) relationship with a high correlation coefficient, r=+ 0.648, between progesterone and estradiol was obtained during the incubation period.KONO et al.: Nesting Behavior and Sex Steroid Hormones 71

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[in Japanese]

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[in Japanese]

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Experiments were conducted to evaluate effect of disinfectant solutions sprayed repeatedly on reduction of viable bacteria contaminating on a chicken house. Three types of disinfectant solution, invert soap, iodophor and orthodichlorobenzene were used.
No significant effect on the reruction of bacteria was observed by spraying either 1 type of the solution repeatedly 2 or 3 times, or 2 or 3 different types of the solution successively. Reduction of bacteria per spraying was less than 1/10 of them contaminated before spraying. The reduction of bacteria by 2nd spraying was smaller than that by 1st spraying. It was observed that the reduction of bacteria per spraying was smaller when the solution was sprayed repeatedly.

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Experiments were conducted to examine effect of temperature of disinfectant solutions on reduction of viable bacteria contaminating on a plywood pieces and bacteria cultured in a broth medium. The plywood pieces were placed on the floor of a chicken house for 1 week. The pieces naturally contaminated with bacteria were dipped into disinfectant solutions kept at either 5°C or 30°C. Invert soap solution diluted 1:100, 1:500 and 1:1000 were used. Iodophor solution diluted 1:500, 1:750 and 1:1000 were also used.
Greater number of viable bacteria were detected from the pieces dipped into invert soap solutions kept at 30°C than those kept at 5°C, though no differences were observed in the bacterial number on the pieces dipped into iodophor solutions kept at 5°C and 30°C (Fig. 1).
Bacteria contaminating on the pieces were cultured by heart infusion broth medium. When bacteria in the broth were soaked in invert soap solutions diluted 1:500 and 1:1000 kept at 5°C, greater number of viable bacteria were detected compared with those soaking to the solutions kept at 30°C. In case of iodophor solutions in any dilutions and invert soap solution diluted 1:100, effect of solutions kept at 5°C and 30°C on the reduction of viable bacteria in the broth medium was not different markedly (Fig. 3).

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[in Japanese]

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