Henning J, Morton J, Hla T, Meers J
School of Veterinary Science, University of Queensland, Brisbane 4072, Queensland, Australia.
Prev Vet Med. 2008 Jul 15;85(3-4):241-52. doi: 10.1016/j.prevetmed.2008.01.014. Epub 2008 Mar 25.
Village chickens are an important livestock for many rural families in Myanmar and other developing countries. Village chickens are kept under free-ranging conditions, with confinement only at night. Therefore, it is likely that some deaths are not observed by farmers. We conducted a longitudinal study from November 2003 until May 2004 to describe temporal patterns of mortality of village chickens in 10 villages in Myanmar. Field veterinarians first identified the numbers of birds in all chicken-owning households in each village. We then selected 307 households randomly with stratification by flock size. Each study household was then visited once monthly at which time questionnaires were completed recording current flock structure and numbers of hatchings, mortalities, sales and birds consumed since the previous visit. In addition, sera were collected from a sample of adult birds and growers. Depending on month and age group of chicken, from 71 to 231 (out of 290-307) households had discrepancies in the counts of birds. For chicks, at least one-quarter of the households had unobserved losses of at least 5 chicks per household (maximum 66 chicks); unobserved losses were less for growers and adult chickens. The median month-specific, village-specific mortality rates per 1000 bird-days at risk (counting missing birds as deaths) ranged from 0.8 to 1.7 for adults, from 0.4 to 4.7 for growers and from 8.0 to 16.5 for chicks. Across all birds, the prevalence of protective titres against Newcastle disease virus was 79% (95% confidence interval 74, 84); higher prevalences of protective titres were associated with reduced mortality rates in the following months.
乡村鸡是缅甸和其他发展中国家许多农村家庭的重要家畜。乡村鸡在自由放养的条件下饲养，仅在夜间圈养。因此，农民可能没有观察到一些死亡情况。我们从2003年11月至2004年5月进行了一项纵向研究，以描述缅甸10个村庄乡村鸡的死亡时间模式。现场兽医首先确定了每个村庄所有养鸡家庭的鸡只数量。然后，我们按鸡群规模分层随机选择了307户家庭。随后，每月对每个研究家庭进行一次走访，此时完成问卷调查，记录自上次走访以来当前鸡群结构、孵化数量、死亡数量、销售数量和食用鸡只数量。此外，还从成年鸡和生长鸡样本中采集了血清。根据鸡的月份和年龄组，在290 - 307户家庭中，有71至231户家庭的鸡只数量统计存在差异。对于雏鸡，至少四分之一的家庭每户有至少5只雏鸡未被观察到的损失（最多66只雏鸡）；生长鸡和成年鸡未被观察到的损失较少。按每1000只鸡日的风险计算，特定月份、特定村庄的成年鸡死亡率中位数（将失踪鸡只算作死亡）为0.8至1.7，生长鸡为0.4至4.7，雏鸡为8.0至16.5。在所有鸡只中，针对新城疫病毒的保护性抗体效价流行率为79%（95%置信区间74, 84）；较高的保护性抗体效价流行率与接下来几个月较低的死亡率相关。
