A survey of the economic impact of subclinical Eimeria infections in broiler chickens in Norway
A survey of the economic impact of subclinical Eimeria infections in broiler chickens in Norway
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DOI：
10.1080/03079450802050705
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发表时间：
2008-01-01
期刊：
影响因子：
2.8
通讯作者：
Kaldhusdal, Magne
中科院分区：
文献类型：
--
作者：
Haug, Anita;Gjevre, Anne-Gerd;Kaldhusdal, Magne
这项工作的目的是检查亚临床球虫感染对肉鸡商业性能的影响，以修改后的欧洲生产指数表示。生产性能数据以及垫料和粪便样本是从 2000 年至 2004 年期间对接受饲用 narasin 的挪威肉鸡进行的两项独立观察调查中收集的。饲养期间收集的每克垫料中的卵囊 (OPG) 数量（研究 1）或屠宰时收集的粪便样本（两项研究），以及艾美耳球虫物种类别的相对频率（两项研究）。研究 2 中对艾美耳球虫属物种进行了基于聚合酶链式反应的鉴定。使用主要物种和 OPG 水平作为标准，测试了与球虫相关的性能受损风险的鸡群（风险鸡群）的定义。在第一项研究中，球虫对表现有显着影响，但在第二项研究中则没有。在研究 1 中，发现以下球虫变量与多变量模型中的性能受损相关：屠宰时的 OPG（序数）、饲养期间的平均 OPG（序数）和风险鸡群（二项式）。研究 1 中屠宰时感染水平为 50 000 OPG 的鸡群的欧洲生产指数降低了 9%。研究 1 和研究 2 之间球虫种群的组成发生了变化，从中型和大型卵囊占主导地位变为小卵囊占主导地位。从研究 1 到研究 2，球虫感染的患病率大幅增加，但两项调查的平均感染水平相似。在研究 1 中，风险鸡群定义可用作球虫相关性能损失的指标，其中亚临床球虫病是一个重要因素。结果表明，亚临床球虫病的经济重要性可能随着时间的推移而发生很大变化，并且他们强调需要对不同现场条件下特定球虫感染的重要性和动态进行群体研究。
The objective of this work was to examine the impact of subclinical coccidial infection on commercial performance, expressed as a modified European Production Index, in broilers. Performance data, and litter and faecal samples, were collected from two independent observational surveys of Norwegian broilers receiving in-feed narasin during 2000 to 2004. Numbers of oocysts per gram (OPG) of litter collected during rearing (Study 1) or faecal samples collected at slaughter (both studies), and relative frequencies of Eimeria species categories (both studies) were calculated. Polymerase chain reaction-based identification of Eimeria species was performed in Study 2. A definition of flocks at risk of impaired performance associated with coccidia (risk flock), using the predominant species and OPG level as criteria, was tested. Coccidia had a significant effect on performance in the first, but not the second study. In Study 1 the following coccidia variables were found to be associated with impaired performance in multivariate models: OPG at slaughter (ordinal), mean OPG during rearing (ordinal) and risk flock (binomial). The European Production Index was 9% lower in flocks with infection levels 50 000 OPG at slaughter in Study 1. The composition of coccidial populations shifted between Study 1 and Study 2, from a dominance of medium and large oocysts to a dominance of small oocysts. There was a substantial increase in prevalence of coccidial infection from Study 1 to Study 2, but mean infection levels were similar in the two surveys. The risk flock definition was useful as an indicator of coccidia-associated performance loss in Study 1, where subclinical coccidiosis was an important factor. The results suggest that the economic importance of subclinical coccidiosis may vary substantially with time, and they emphasize the need for population studies on the importance and dynamics of specific coccidial infections under different field conditions.