Hewson K A, Robertson T, Steer P A, Devlin J M, Noormohammadi A H, Ignjatovic J
Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria, 3030, Australia.
Aust Vet J. 2014 Apr;92(4):132-8. doi: 10.1111/avj.12156.
This investigation aimed to determine if there was a relationship between the production of eggs with poor internal quality, as measured by poor Haugh units, by Australian layer flocks and the detection of infectious bronchitis virus (IBV) in the hens. Other risk factors including flock size, flock type, flock age, chicken breed and vaccination frequency were also assessed.
The study group comprised 17 flocks from 14 farms. Data relating to the factors investigated were requested on a regular basis. The Haugh unit data were used to grade eggs as good or poor based on the age and flock at the time of data collection. Cloacal swabs were collected from 20 chickens in each flock approximately every 6 weeks.
IBV was detected from a majority of the flocks and in 68% of cases the IBV strain detected was an A-vaccine-related field strain. Three variant strains were detected. Detection of IBV in a flock, the farm type and flock size were identified as potential risk factors for the production of eggs with poor Haugh units.
IBV is prevalent in Australian layer flocks, but infection was primarily subclinical. The results complement previous reports indicating that there are many potential risk factors for the production of eggs with poor Haugh units.
本研究旨在确定澳大利亚蛋鸡群产出哈氏单位低（即蛋的内部品质差）的鸡蛋与母鸡感染传染性支气管炎病毒（IBV）之间是否存在关联。同时还评估了其他风险因素，包括鸡群规模、鸡群类型、鸡群年龄、鸡的品种和疫苗接种频率。
研究组包括来自14个农场的17个鸡群。定期收集与所调查因素相关的数据。根据收集数据时的年龄和鸡群情况，利用哈氏单位数据将鸡蛋分为优质或劣质。大约每6周从每个鸡群的20只鸡采集泄殖腔拭子。
在大多数鸡群中检测到了IBV，在68%的病例中检测到的IBV毒株是与A疫苗相关的野毒株。检测到了三种变异毒株。鸡群中IBV的检测、农场类型和鸡群规模被确定为产出哈氏单位低的鸡蛋的潜在风险因素。
IBV在澳大利亚蛋鸡群中普遍存在，但感染主要为亚临床感染。研究结果补充了之前的报告，表明产出哈氏单位低的鸡蛋存在许多潜在风险因素。
