Effects of ketamine, xylazine, and a combination of ketamine and xylazine were studied in 12 male Pekin ducks (7 to 12 weeks old; mean [+/- SD] body weight, 3.1 +/- 0.3 kg). After venous and arterial catheterization and fixation of a temperature probe in the cloaca, each awake duck was confined, but not restrained, in an open box in a dimly lit room. Blood pressure and lead-II ECG were recorded. Three arterial blood samples were collected every 15 minutes over a 45-minute period (control period) and were analyzed for pHa, Paco2 and Pao2. After the control period, each duck was assigned at random to 1 of 3 drug groups: (1) ketamine (KET; 20 mg/kg of body weight, IV), (2) xylazine (XYL; 1 mg/kg, IV), and (3) KET + XYL (KET 20 mg/kg and XYL, 1 mg/kg; IV). Measurements were made at 1, 5, 10, 15, 30, 45, 60, and 90 minutes after drug administration. All ducks survived the drug study. Cloacal temperature was significantly (P less than or equal to 0.05) increased above control cloacal temperature at 90 minutes after the administration of ketamine, and from 10 through 90 minutes after administration of ketamine plus xylazine. In ducks of the KET group, pHa, Paco2, and Pao2, remained unchanged after administration of the drug. In ducks of the XYL group, pHa and Pao2 decreased significantly (P less than or equal to 0.05) from control values for all time points up to and including 15 minutes after drug administration. In ducks of the KET + XYL group, pHa and Pa02 were significantly (P less than or equal to 0.05) decreased at all time points up to and including 45 and 15 minutes, respectively, after administration of the drugs. In ducks of the XYL group, Paco2 increased significantly (P less than 0.05) during the first 15 min. after drug administration, and for 45 min. after administration of KET + XYL. Results indicated that ketamine when given alone to ducks, was not associated with pulmonary depression.

Effect of strain (Khaki Campbell, Indigenous) and age (224 and 280 days) of ducks on the physical egg quality and presence of off-flavour in eggs was studied. The average of egg weight, yolk index and percent yolk weight for the two ages under study were significantly (P0.05) higher in Indigenous duck eggs whereas the same average value for albumen index, Haugh Unit score and percent albumen were higher in Khaki Campbell eggs. However, shape index, yolk colour score, shell thickness and percent shell weight of eggs were comparable for the two strains. Age of ducks had an insignificant influence on shape index, albumen height, shell thickness and yolk index as evident from the least difference between average values of two strains under study. But, the average values of the two strains under study were significantly affected by age for A.I., H.U. score, % albumen weight, % shell weight and % yolk weight. Presence of off-flavour was more pronounced in Khaki Campbell eggs than that of indigenous eggs.

To establish vaccine strains of H5 and H7 influenza viruses, A/duck/Hokkaido/Vac-1/04 (H5N1) [Vac-1/04 (H5N1)], A/duck/Hokhaido/Vac-3/07 (H5N1) [Vac-3/07 (H5N1)], and A/duck/Hokkaido/Vac-2/04 (H7N7) [Vac-2/04 (H7N7)] were generated from non-pathogenic avian influenza viruses isolated from migratory ducks. Vac-1/04 (H5N1) and Vac-3/07 (H5N1) were generated by genetic reassortment between H5N2 or H5N3 virus as an HA gene provider and H7N1 or H6N1 virus as an NA gene provider. Vac-2/04 (H7N7) was a genetic reassortant obtained using H7N7 and H9N2 viruses to give high growth character of the H9N2 virus in chicken embryonated eggs. The results of sequence analyses and experimental infections revealed that these H5N1 and H7N7 reassortant viruses were non-pathogenic in chickens and embryos, and had good growth potential in embryonated eggs. These viruses should be useful to develop vaccines against H5 and H7 highly pathogenic avian influenza viruses.

The hemagglutinin (HA) of six H5 influenza virus strains isolated from ducks in Japan and China in 1976 to 1996 were analyzed antigenically and genetically. Antigenic analysis using a panel of monoclonal antibodies revealed that the HA of H5 influenza viruses isolated from ducks are antigenically closely related to each other. Phylogenetic analysis indicates that the isolates from ducks in Hokkaido were derived from an ancestor common with the highly pathogenic isolates from chickens and human

This study was conducted in order to observe the changes in cellular association of seminiferous tubules from 4 to 22 weeks of age and to obtain the cycle and relative duration of seminiferous epithelia from 24 weeks of age in male ducks. Fifety-five male ducks were used in the experiment and divided into 11 groups, consisting of 5 male ducks each, with 2 weeks intervals from 4 to 24 weeks of age. The body and tests weight showed most rapid increase during 4 to 6 weeks and 18 to 22 weeks of age, respectively. The seminiferous tubules were abruptly enlarged in diameter of tubules during 18 to 22 weeks of age. Gonocytes were seen from 4 to 6 weeks of age, however they were not observed as from 8 weeks of age. Both type Ap spermatogonia and type Ad spermatogonia occurred from 8 to 12 weeks of age, while spermatocytes and spermatids were beginning to appear at 16 weeks and 18 weeks of age, respectively. Spermatozoa were first observed at 20 weeks of age. Full spermatogenic activity was completed at the age of 20 weeks. Average paired weight of the testes in male ducks was 78g at 24 weeks of age and its ratio spermatogenic activity was completed at the age of 20 weeks. Average diameter of seminiferous epithelium at 22 weeks of age was 232 micro m, and average numbers of Sertoli cell, spermatogonia, spermatocyte, spermatids and spermatozoa in the cross section of seminiferous epithelium were 15.30, 59.08, 41.78, 71.11 and 165.30, respectively. Spermatogonia and spermatids were classified into 2 and 4 types, respectively. The cycle of the seminiferous epithelium could be divided into 5 stages at 24 weeks of age. The relative frequencies of stages from I to V were 13.5 %, 25.0 %, 22.3 %, 20.6 % and 18.7 %, respectively. Thus, establishment of spermatogenesis in male ducks were beginning to appear at 20 weeks of age

An outbreak of duck virus hepatitis was confirmed for the first time in Korea from ducklings having up to 40-65% mortality in less than 15-day-old ducklings of two farms located in the vicinity of Kwangju city. The infected ducks showed sudden death and opisthotonus position. The predominant gross lesions were found in the liver, showing enlargement and petechial or ecchymotic hemorrhages. The microscopic findings consisted of fatty changes and necrosis of the hepatic cells, and proliferation of the bile duct epithelium