Gaydos Technical Services, LLC, Dallas, TX 75215,
Michigan State University Veterinary Diagnostic Laboratory, Lansing, MI 48910.
Avian Dis. 2024 Sep;68(3):282-286. doi: 10.1637/aviandiseases-D-24-00019.
A four-house broiler breeder farm of approximately 35-wk-old hens was diagnosed with egg drop syndrome (EDS'76) utilizing PCR and hemagglutination inhibition (HI) testing. Based on communication with local practitioners, the geographic area near where this flock was located had numerous EDS'76 cases in table egg layers at the time of diagnosis. An egg production drop was seen in the broiler breeder flock over a 7-day period, which prompted an investigation. During this investigation, a significant number of shell-less, wrinkled, and pale eggs were noted, but no increases in mortality or respiratory signs were observed. The disease and subsequent production drops spread horizontally across the farm over a 5-wk period. Production returned to approximately the breed standard egg production 4 wk after initial egg production drop. However, hatching egg utilization continued to be reduced for another 2 wk because of the number of thin-shelled eggs. A similar pattern of drop in egg production and subsequent return was observed in the other houses. No significant lesions were noted in the tissues submitted for histopathology. Differential diagnoses that could cause shell abnormalities and egg production drops were ruled out by submitting appropriate samples for diagnostic investigation. Egg drop syndrome 76 PCR was performed on shell-less eggs and EDS'76 was detected by PCR at two separate laboratories. Subsequently, serum was submitted for HI and positive results were found in each house as they showed egg production drop concurrent with shell abnormalities. At the time the flocks returned to breed standard production, EDS'76 titers were consistent with a uniformly exposed and seroconverted flock. The authors suspect that immunosuppression as pullets played a role in this flock being impacted by EDS. No other farms in the company's system were observed with production drops or shell abnormalities similar to this case.
一个拥有约 35 周龄母鸡的四栋肉鸡种鸡场，通过 PCR 和血凝抑制（HI）检测诊断为蛋鸡产蛋下降综合征（EDS'76）。根据与当地从业者的沟通，在诊断时，该鸡群所在的地理区域有许多蛋鸡发生 EDS'76 病例。肉鸡种鸡群在 7 天的时间内出现产蛋下降，促使进行了调查。在调查过程中，发现大量无壳、皱缩和苍白的鸡蛋，但没有观察到死亡率或呼吸道症状增加。这种疾病及其随后的产蛋下降在 5 周内在整个农场水平传播。在最初的产蛋下降后大约 4 周，产蛋量恢复到大约种鸡的标准产蛋量。然而，由于薄壳蛋的数量，孵化蛋的利用率仍持续减少了 2 周。在其他鸡舍中也观察到类似的产蛋下降和随后恢复的模式。提交进行组织病理学检查的组织中没有明显的病变。通过提交适当的样本进行诊断调查，排除了可能导致蛋壳异常和产蛋下降的其他鉴别诊断。对无壳蛋进行了 EDS'76 PCR 检测，在两个不同的实验室通过 PCR 检测到了 EDS'76。随后，血清被提交进行 HI 检测，每个鸡舍都发现了阳性结果，因为它们在出现蛋壳异常的同时也出现了产蛋下降。当鸡群恢复到种鸡的标准生产时，EDS'76 滴度与普遍暴露和血清转化的鸡群一致。作者怀疑作为育成鸡的免疫抑制在该鸡群受到 EDS 的影响中发挥了作用。在公司系统中没有观察到其他农场出现与该病例类似的产蛋下降或蛋壳异常。
