Zachar Tara, Popowich Shelly, Goodhope Bob, Knezacek Tennille, Ojkic Davor, Willson Philip, Ahmed Khawaja Ashfaque, Gomis Susantha
Department of Veterinary Pathology, Western College of Veterinary Medicine (Zachar, Popowich, Goodhope, Ahmed, Gomis), Department of Animal and Poultry Science, College of Agriculture and Bioresources (Knezacek), and Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan (Willson); Animal Health Laboratory, University of Guelph, P.O. Box 3612, Guelph, Ontario (Ojkic).
Can J Vet Res. 2016 Oct;80(4):255-261.
While the prevalence of infectious bursal disease virus (IBDV) on chicken farms in some provinces of Canada has been documented, the economic impact of variant IBDV infection on the broiler chicken industry in Saskatchewan has not. The objectives of this study were to identify the variant strains of IBDV circulating on Saskatchewan chicken farms and evaluate their economic impact on broiler production. Infection due to IBDV was detected in 43% of Saskatchewan chicken farms, with variant strains detected in infected birds closely related predominantly to NC171, 586, and Delaware-E. Infected flocks showed an IBDV antibody titer of 4236 geometric mean (GM), whereas an antibody titer of 157 GM was measured in uninfected flocks. Infected flocks had very low (0.06) bursa-to-body-weight (BBW) ratio (an indicator of immunity) compared to high BBW ratio (0.17) in uninfected flocks, which suggests a significant immunosuppression in the former. Flocks positive for IBDV had mean mortality of 8.6% and mean condemnation of 1.5%. In contrast, mean mortality in uninfected flocks was 6.1% and mean condemnation was 1.1%. The live market weight per grow area at 37 d of age was 29.3 kg/m in infected flocks and 34.0 kg/m in flocks without IBDV infection. Flock mortality and condemnation rate were positively correlated with IBDV infection, whereas low BBW ratio was inversely correlated, as expected. Overall, IBDV-infected flocks had higher mortality, bursal atrophy, poorer feed conversion ratio (FCR), and decreased meat production. Our data suggest that the broiler chicken industry in Saskatchewan loses 3.9 million kilograms of meat production per year due to variant IBDV strains.
虽然加拿大一些省份的养鸡场中传染性法氏囊病病毒（IBDV）的流行情况已有记录，但变异型IBDV感染对萨斯喀彻温省肉鸡产业的经济影响尚无相关研究。本研究的目的是确定萨斯喀彻温省养鸡场中传播的IBDV变异株，并评估其对肉鸡生产的经济影响。在萨斯喀彻温省43%的养鸡场中检测到IBDV感染，在感染禽类中检测到的变异株主要与NC171、586和特拉华-E密切相关。感染鸡群的IBDV抗体滴度几何平均值（GM）为4236，而未感染鸡群的抗体滴度GM为157。与未感染鸡群的高法氏囊与体重比（BBW）（0.17）相比，感染鸡群的BBW比非常低（0.06）（免疫指标），这表明前者存在显著的免疫抑制。IBDV呈阳性的鸡群平均死亡率为8.6%，平均废弃率为1.5%。相比之下，未感染鸡群的平均死亡率为6.1%，平均废弃率为1.1%。感染鸡群在37日龄时每个生长区域的活禽市场体重为29.3千克/平方米，未感染IBDV的鸡群为34.0千克/平方米。鸡群死亡率和废弃率与IBDV感染呈正相关，而低BBW比与预期相反呈负相关。总体而言,感染IBDV的鸡群死亡率更高、法氏囊萎缩、饲料转化率（FCR）更差且肉类产量下降。我们的数据表明，由于变异型IBDV毒株，萨斯喀彻温省的肉鸡产业每年损失390万千克的肉类产量。
