Carrique-Mas Juan, Van Nguyen Thi Bich, Cuong Nguyen Van, Truong Bao Dinh, Kiet Bach Tuan, Thanh Pham Thi Huyen, Lon Nguyen Ngoc, Giao Vu Thi Quynh, Hien Vo Be, Padungtod Pawin, Choisy Marc, Setyawan Erry, Rushton Jonathan, Thwaites Guy
Oxford University Clinical Research Unit, Vietnam; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, United Kingdom.
Oxford University Clinical Research Unit, Vietnam.
Prev Vet Med. 2019 Apr 1;165:15-22. doi: 10.1016/j.prevetmed.2019.02.005. Epub 2019 Feb 11.
Raising chickens in small-scale flocks following all-in-all-out management is common in the Mekong Delta of Vietnam. These flocks represent an intermediate category between backyard and intensive (industrial) farming systems. However, little is known about the occurrence and burden of disease and/or mortality in such flocks, and their potential association with antimicrobial usage (AMU). We investigated mortality, disease and weekly antimicrobial use (AMU) in 124 cycles of meat chicken flocks raised in 88 farms in the Mekong Delta of Vietnam (with a median cycle duration of 18 weeks [inter-quartile range IQR 17-20]). We visited each farm 4 times per cycle to review data collected weekly by the farmers on clinical signs, mortality, and AMU. The overall probability of disease and AMU were 0.31 (95% CI 0.29-0.32) and 0.26 (95% CI 0.24-0.28), respectively. The average weekly incidence of mortality was 2.6 (95% CI 2.2-3.0) per 100 birds. Both the probabilities of a flock experiencing disease and mortality, as well as of using antimicrobials decreased with the flock's age. However, mortality peaked at the 5-10 week period. The only significant explanatory factors associated with presence of disease was the stage of production ≥5 weeks (protective) (OR ≤ 0.51). Factors independently associated with AMU (p < 0.05) were: (1) Number of chickens (log) (OR=1.46), (2) Stage of production ≥5 weeks (OR≤0.67) (protective), (3) Cao Lanh district (OR=2.23), (4) Density of veterinary drug shops at commune level (log) (OR=1.58), and (5) Disease in flocks (OR=1.80). Factors independently associated with overall increased weekly incidence of mortality (p < 0.05) were: (1) High level of education attainment (secondary education or higher) (Hazard rate Ratio [HR]=1.70), (2) number of chickens (log) (HR=1.39), and (3) Stage of production >5 weeks (HR≤2.14). In flocks reporting disease, AMU significantly reduced the incidence of mortality (HR=0.90). These results confirm an exceptionally high mortality in chicken flocks in the area, jeopardizing the profitability and sustainability of these small-scale farming systems. The data also suggest an association between nearby access to antimicrobials and AMU, and a high correlation of AMU over consecutive cycles. The atomized farming landscape of the Mekong Delta, the high incidence of disease and mortality, and the unrestricted and easy access to antimicrobials present major challenges to the implementation of policies aimed at AMU reductions.
在越南湄公河三角洲，采用全进全出管理方式小规模养鸡很常见。这些鸡群属于后院养殖和集约化（工业化）养殖系统之间的中间类别。然而，对于此类鸡群中疾病的发生、负担和/或死亡率及其与抗菌药物使用（AMU）的潜在关联，人们了解甚少。我们调查了越南湄公河三角洲88个农场饲养的124个肉鸡养殖周期中的死亡率、疾病情况和每周抗菌药物使用情况（养殖周期中位数为18周[四分位间距IQR 17 - 20]）。我们每个养殖周期走访每个农场4次，以审查农民每周收集的关于临床症状、死亡率和抗菌药物使用情况的数据。疾病和抗菌药物使用的总体概率分别为0.31（95%置信区间0.29 - 0.32）和0.26（95%置信区间0.24 - 0.28）。每100只鸡的平均每周死亡率为2.6（95%置信区间2.2 - 3.0）。鸡群患病、死亡以及使用抗菌药物的概率均随鸡群年龄增长而降低。然而，死亡率在5 - 10周龄时达到峰值。与疾病存在显著相关的唯一解释因素是生产阶段≥5周（具有保护作用）（比值比≤0.51）。与抗菌药物使用独立相关（p < 0.05）的因素有：（1）鸡的数量（对数）（比值比 = 1.46），（2）生产阶段≥5周（比值比≤0.67）（具有保护作用），（3）曹兰区（比值比 = 2.23），（4）公社一级兽药商店密度（对数）（比值比 = 1.58），以及（5）鸡群患病（比值比 = 1.80）。与每周总体死亡率增加独立相关（p < 0.05）的因素有：（1）高学历（中等教育或更高）（风险率比[HR] = 1.70），（2）鸡的数量（对数）（HR = 1.39），以及（3）生产阶段>5周（HR≤2.14）。在报告有疾病的鸡群中，抗菌药物使用显著降低了死亡率（HR = 0.90）。这些结果证实该地区鸡群死亡率极高，危及这些小规模养殖系统的盈利能力和可持续性。数据还表明附近获取抗菌药物与抗菌药物使用之间存在关联，且连续养殖周期中抗菌药物使用高度相关。湄公河三角洲分散的养殖格局、高发病率和死亡率以及抗菌药物不受限制且易于获取，给旨在减少抗菌药物使用的政策实施带来了重大挑战。
