To investigate the effect of phase feeding of amino acids for laying hens during laying period, the laying period from 20 to 80 weeks of age was divided into 3 phases as 20-30, 30-60 and 60-80 weeks of age, and the hens were fed with 8 feeding programs. Five dietary amino acids (lysine, methionine, threonine, isoleucine and tryptophan) levels were adjusted to 100, 115 and 130% of the NRC requirement. The hens in non phase feeding groups were fed 130, 115, 100% (groups 1, 2, 3) and commercial diet as a reference (group 9). The hens in phase feeding groups were fed with following programs: 130-115-115 (group 4), 130-115-100 (5), 130-100-130 (6), 115-115-100 (7) or 100-130-130% (8) for phase I-II-III. The oviposition was recorded every day and egg weight was measured every Monday, Wednesday and Friday throughout the experimental period. And the eggshell strength, eggshell weight and Haugh unit were estimated every 10 weeks after 30 weeks of age.
The first egg age and egg weight were not different among dietary amino acid levels. However the hens in 100% diet groups decreased their body weight considerably after the start of laying. Their performance was also inferior to other groups. When the dietary amino acid level was decreased from 130 to 115 to 100% gradually (group 5), there was no difference in the performance throughout the experimental period compared with 130% diet (group 1). However, the length of laying peak in experimental groups was shorter than that in reference group. The egg weight of hens fed 130% diet was the largest. The eggshell strength and Haugh unit were decreased with age. But the effective phase feeding program to maintain the egg quality was not determined.

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Sulfamonomethoxine (SMM) was fed to laying hens for 5 days at the dietary levels of 0, 100, 200 and 400ppm, and contents of SMM in eggs laid during SMM feeding were determined by highperformance liquid chromatography.
Relationship between SMM (yppm) in whole egg and product of dietary SMM level (xppm) and days of SMM feeding (T, T≤3) could be well described by following equation.y=0.005048•xTAfter 3 days of SMM feeding, SMM content in whole egg reached a plateau at 0.01514x (=0.005048•3x)ppm.
To elucidate the easiness of transfer of SMM into whole egg, SMM content (y) in whole egg under a fixed condition of administration (x=100 and T=3) was estimated. The value of SMM, 1.51ppm, was comparable to that of sulfadimethoxine, 1.10ppm, and was much larger than those of other antibiotics and synthetic antibacterials estimated under the same condition.

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Sulfamonomethoxine (SMM) was fed to laying hens for 5 days at the dietary level of 400ppm, and thereafter, dietary SMM was withdrawn by changing the diet to SMM free diet for another 14 days. Contents of SMM in eggs laid after the withdrawal were determined by highperformance liquid chromatography.
Disappearance pattern of SMM from whole egg could be well described by following equation applied to onecompartment model, y=A•e^-0.7834t where, y is SMM content (ppm) in whole egg, t days after the withdrawal of SMM and A the initial value of SMM content, which showed the SMM content in whole egg laid at 0 day of the withdrawal of dietary SMM. The coefficient, -0.7834, is a characteristic value indicating the speed of disappearance of SMM from whole egg. Biological half life of SMM in whole egg was estimated to be 0.88 (=log_e2/0.7834) days with 95% confidence interval from 0.81 to 0.98 days. This value was equaled that of sulfadimethoxine, and was much shorter than that of 2 antibiotics and 4 synthetic antibacterials.

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Inactivated subunit vaccine of Newcatle disease virus (NDV) was prepared from NDV fusion protein in Bombyx mori pupae by gene transfer using a hybrid baculovirus vector, and its potency was evaluated. The subunit vaccine was very effective against challenge by virulent NDV. Neutralization antibody was produced in vaccinated chickens with the extremelydiluted vaccine, whereas hemagglutinatinginhibition (HI) antibody was not detected in vaccinated chickens even with the mildlydiluted or nondiluted vaccines. HI titers were elevated markedly in resisted chickens against the challenge. The potency of the vaccine was very high and stable after refrigeration storage for 9 months. The antigen prodduced in Bombyx mori pupae by the hybrid baculovirus recombinant was also stable, even if serial passage was done five times in Spodoptera frugiperda cells.

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Some properties of infectious bronchitis virus (IBV) passed through 50nm mesh filter were compared with IBV nonpassed through the filter and were tried to purify a small size IBV isolated from nephritic infectious bronchitis of chicken.
There were markedly difference in size of the virus passed through 50nm mesh filter by electron microscopic observation. However, no differences were observed in other properties such as typical structure, resistance to treatments with pH3.0 and heating, trypsin, ether and chloroform between large and small size virus groups. Pathogenicity to chickens of the two virus groups was also the same. Moreover, the small size of IBV could not purified, even if the virus was passaged in chicken embryo. In addition, population of small size IBV was not increased in the progeny virus after passage.

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