Hot water treatments reduce leaf yellowing and extend vase life of Asiatic hybrid lilies

The vase life of Asiatic lilies can be limited by leaf yellowing, which can be caused by exposure to low light or temperature during winter growth or in storage. We examined the use of postharvest hot water treatments (HWTs) as a means of reducing leaf senescence in stored (4 °C for 2 weeks) and non-stored Asiatic hybrid lily ‘Elite’ (Lilium sp.). A range of HWTs (45-55 °C for 2.5 or 5 min) was applied to leaves on cut lily stems (but not flowers). Higher temperatures and the longer duration resulted in heat damage, but treatments of 50 °C for 5 min and 52.5 °C for 2.5 min were found to be optimal for minimising leaf yellowing with trace levels of heat damage for both non-stored and stored stems. The onset of yellowing was delayed by 3-4 d, and the occurrence of an unacceptable level of yellowing eliminated for up to 12 d (compared with <6 d for control stems). The physiological effects of these optimal HWTs were examined in terms of water uptake, chlorophyll fluorescence and chlorophyll degradation. Water uptake for optimal HWTs during shelf life was reduced by more than 50% of the control stems. Chlorophyll fluorescence of leaves on control stems showed a reduction in yield (F_v/F_o) over time, which was more marked in lower than upper leaves (thus correlating with yellowing, which was more severe in the lower leaves). Although both optimal HWTs resulted in an initial reduction in yield, there was a recovery over time resulting in a yield that, by 12 d, was as high or significantly higher than control leaves (particularly for the lower leaves). All treatments showed a reduction in chlorophyll content (total, chlorophyll a and chlorophyll b), but control leaves had significantly lower levels after 7 d. HWTs show potential as a non-chemical, simple means of delaying leaf yellowing of Asiatic lilies and thus increasing vase life.     

Application of the Enfer chemiluminescent multiplex ELISA system for the detection of Mycobacterium bovis infection in goats

A study was conducted to optimise a multiplex serological immunoassay for use in identification of goats infected with Mycobacterium bovis. To assess assay specificity, 31 goats with a history of being free from M. bovis infection were used. To determine assay sensitivity, 180 Single Intradermal Comparative Tuberculin test (SICTT) positive goats were recruited. Additionally, 286 SICTT negative goats classed as potentially exposed animals present in the same positive herds were also included in the study. The results of the assay demonstrated a specificity of 100%. The multiplex assay detected 57/60 SICTT (95.0%) positive animals in one M. bovis infected herd and 120/120 (100%) in a second herd. In a separate experiment, 28 M. caprae culture confirmed infected goats from Spain were assayed, of which 24 (85.7%) were found positive in the test. The results show that inclusion of an antibody based assay can improve the ability to identify M. bovis and M. caprae infected goats. With further development and validation the multiplex assay may prove to be a useful tool for control of M. bovis and M. caprae infection in goats.     

Prevalence and pathogenicity of Aeromonas hydrophila

A field survey to determine the prevalence of Aeromonas hydrophila revealed a recovery rate of 8% in 141 specimens derived from a range of live, companion, and exotic avian species. The prevalence rate was similar in 240 sequential postmortem submissions during 1984. Studies on the pathogenicity of A. hydrophila showed that 2-to-4-day-old chicks and turkey poults were highly susceptible to exposure via the subcutaneous, yolk-sac, and intracerebral routes, and mortality of 80-100% occurred within 48 hours of inoculation. Ducklings aged 4 days were generally refractory to exposure.     

Campylobacter jejuni contamination of eggs

Contamination of commercial table eggs with a fecal suspension containing 4.4×10⁶ CFU/gCampylobacter jejuni resulted in shell penetration in 3/70 eggs and recovery of the organism from homogenized egg contents in 1/70 eggs. Viability ofC. jejuni on the shell surface was retained for only 16 hours, attributed to desiccation of the fecal suspension. A field survey of three commercial laying farms and their associated egg-packing plants showed that hens demonstrated to be fecal shedders ofC. jejuni (12% to 62% incidence) did not produce infected eggs. The organism could not be detected in the environment of the packing plant, including grading machinery and effluent.     

Decontamination of Campylobacter jejuni on chicken drumsticks using chemicals and radiation

A trial was conducted to compare the efficacy of four disinfectants and radiation to reduce the level of C. jejuni contamination on poultry meat. Two levels of each treatment were applied to chicken drumsticks inoculated with a known concentration of a strain of Campylobacter jejuni, biotype 1, isolated from a human patient with diarrhea.Radiation using a cobalt-60 source at a level of 0.5 KGy effected a 99% surface reduction in C. jejuni. With a mean initial surface contamination level of 1.1 × 10³ Colony Forming Units/cm², 1 KGy completely eliminated C. jejuni. Glutaraldehyde at 0.5% concentration for 30 minutes had an efficacy similar to the lower dose of radiation. Chlorine showed a negligible effect on C. jejuni. Succinic acid and Poly (hexamethylenebiguanide hydrochloride) were statistically similar in their effectiveness, ranking between glutaraldehyde and chlorine.These results strongly indicate that, of the alternatives tested, low-dose radiation is the method of choice for reducing Campylobacter contamination of poultry products.     

Etiology and pathogenesis of necrotic enteritis

Sporulated oocysts of Eimeria acervulina were administered orally to cage-housed broilers at a dose of 3.5 X 10(5) resulted in mild subclinical coccidiosis. Clostridium perfringens incorporated in feed at a level of 2.5 X 10(8) organisms/g. produced lesions characteristic of necrotic enteritis. Mortality of 8% (7/80) occurred in birds fed a ration inoculated with Cl. perfringens alone. Mortality of 35% (28/80) was observed in birds which received an oral dose of E. acervulina and which were fed simultaneously with a ration containing Cl. perfringens. Birds which were fed an inoculated ration two days after an oral dose of E. acervulina showed 41% (33/80) mortality. Birds which received an inoculated ration for two days before administration of an oral dose of E. acervulina demonstrated 18% mortality (15/80). Birds which were fed an inoculated ration four days after an oral dose of E. acervulina showed 10% mortality. Infection with E. acervulina reduced the pH of intestinal contents with a simultaneous depression in serum protein. A 39% increase in intestinal passage time from 178 to 248 minutes occurred on the fifth day after infection with E. acervulina. These experiments suggest that necrotic enteritis, attributed to proliferation of a toxigenic strain of Cl. perfringens, followed intestinal stasis and minimal lesions induced by mild intestinal coccidiosis.     

Cutaneous and pulmonary mycosis in green anacondas (Euncectes murinus).

Two dead, captive green anacondas (Eunectes murinus), including one male and one female, submitted for necropsy were in poor body condition, having multiple, scattered, dark red foci on the scales and mottled lungs. Both snakes had severe mycotic dermatitis. In addition, the male snake had mycotic stomatitis, and the female snake had mycotic pneumonia. Trichophyton sp., Verticillium sp., and Alternaria sp. were isolated from the dermal lesions. The pulmonary lesions were morphologically consistent with Aspergillus sp. Bacterial organisms isolated from skin and internal organs included Chryseobacterium meningosepticum, Stenotrophomonas maltophilia, Aeromonas hydrophila, and Providencia rettgeri. Mycotic diseases can be devastating to reptiles, and suboptimal husbandry and captivity were likely the predisposing factors that led to opportunistic invasion in these snakes.     

美国家禽生产与加工设备最新进展——2008年国际家禽科学研讨会内容采撷

2008年年初,在美国亚特兰大召开了家禽博览会,同期举行了由美国禽蛋协会组织的国际家禽科学研讨会,本文对相关成果进行介绍.