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Effect of vegetation density on survival of South African free-ranging indigenous chicken broods
Tropical Animal Health and Production ( IF 1.7 ) Pub Date : 2020-11-25 , DOI: 10.1007/s11250-020-02446-9
N. Chikumba , M. Chimonyo

The survival of juveniles from hatching until recruitment is a critical determinant of indigenous chicken population growth under extensive free-range production systems. A longitudinal study was conducted to investigate the impact of vegetation cover on survival of indigenous chicken broods in Msinga, South Africa. Survival records of 281 chicks hatched in sparsely vegetated (SV) communal lands and 233 hatched chicks in densely vegetated (DV) resettlement areas were collected from hatch until 12 weeks of age. Data on probable cause of death of individual chicks was collected using a structured checklist. Kaplan-Meir survival distributions and log rank tests were used to estimate the survival functions of broods between vegetation cover types. Logistic regression analysis was used to determine the association between management factors and mortality risk in SV and DV. Chick survival from hatching to 12 weeks was higher in SV (55 ± 3.14%) than DV (41 ± 4.19%) (P < 0.05). Mean chick survival time did not differ between SV (56 ± 3.30 days) and DV (49 ± 3.23 days) (P > 0.05). Aerial predators were the major cause of chick mortality (over 60%) followed by terrestrial predators (30%) in both vegetation cover types. The odds of mortality were higher in DV compared to SV (P < 0.05). It was concluded that increasing vegetation cover decreases survival of scavenging chicks between hatching and end of brooding at 12 weeks of age, and therefore brood management actions should ensure adequate protection of free-ranging chicken broods in densely vegetated rearing habitats.



中文翻译:

植被密度对南非散养土鸡种群存活的影响

从广泛的放养生产系统来看,从孵化到募集的幼鱼的存活率是决定本地鸡种群增长的关键因素。进行了一项纵向研究,以调查植被覆盖对南非Minga土著鸡群生存的影响。从孵化到12周龄,收集了281只在稀疏植被(SV)公共土地上孵化的小鸡和233只在密集植被(DV)安置区孵化的小鸡的存活记录。使用结构化清单收集有关个别小鸡可能死亡原因的数据。Kaplan-Meir生存分布和对数秩检验用于估计植被覆盖类型之间育雏的生存功能。Logistic回归分析用于确定SV和DV中管理因素与死亡风险之间的关联。SV(55±3.14%)的雏鸡从孵化到12周的存活率高于DV(41±4.19%)(P  <0.05)。SV(56±3.30天)和DV(49±3.23天)之间的平均雏鸡存活时间没有差异(P  > 0.05)。在两种植被覆盖类型中,空中掠食者是引起小鸡死亡的主要原因(超过60%),其次是陆地掠食者(30%)。与SV相比,DV的死亡率更高(P  <0.05)。结论是,增加植被覆盖度会降低在孵化和育雏结束之间在12周龄时清道夫小鸡的存活,因此育雏管理措施应确保在茂密的饲养栖息地中自由放养的雏鸡得到充分的保护。

更新日期:2020-11-27
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