Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, Brazil; Departamento de Zootecnia, Universidade Federal de Santa Maria, Brazil.
Vet Parasitol. 2013 Sep 1;196(1-2):77-84. doi: 10.1016/j.vetpar.2013.01.013. Epub 2013 Jan 24.
A meta-analysis was carried out to (1) study the relation of the variation in feed intake and weight gain in broilers infected with Eimeria acervulina, Eimeria maxima, Eimeria tenella, or a Pool of Eimeria species, and (2) to identify and to quantify the effects involved in the infection. A database of articles addressing the experimental infection with Coccidia in broilers was developed. These publications must present results of animal performance (weight gain, feed intake, and feed conversion ratio). The database was composed by 69 publications, totalling around 44 thousand animals. Meta-analysis followed three sequential analyses: graphical, correlation, and variance-covariance. The feed intake of the groups challenged by E. acervulina and E. tenella did not differ (P>0.05) to the control group. However, the feed intake in groups challenged by E. maxima and Pool showed an increase of 8% and 5% (P<0.05) in relation to the control group. Challenged groups presented a decrease (P<0.05) in weight gain compared with control groups. All challenged groups showed a reduction in weight gain, even when there was no reduction (P<0.05) in feed intake (adjustment through variance-covariance analysis). The feed intake variation in broilers infected with E. acervulina, E. maxima, E. tenella, or Pool showed a quadratic (P<0.05) influence over the variation in weight gain. In relation to the isolated effects, the challenges have an impact of less than 1% over the variance in feed intake and weight gain. However, the magnitude of the effects varied with Eimeria species, animal age, sex, and genetic line. In general the age effect is superior to the challenge effect, showing that age at the challenge is important to determine the impact of Eimeria infection.
进行了一项荟萃分析，以：（1）研究感染堆型艾美耳球虫、巨型艾美耳球虫、毒害艾美耳球虫或艾美耳球虫混合感染的肉鸡采食量和体重增加的变化关系，以及（2）确定和量化感染涉及的影响。开发了一个针对堆型艾美耳球虫感染肉鸡的文献数据库。这些出版物必须提供动物生产性能（体重增加、采食量和饲料转化率）的结果。该数据库由 69 篇出版物组成，总共约有 44000 只动物。荟萃分析遵循三个连续分析：图形分析、相关性分析和方差协方差分析。感染堆型艾美耳球虫和毒害艾美耳球虫的鸡群的采食量与对照组没有差异（P>0.05）。然而，感染巨型艾美耳球虫和混合感染组的采食量分别比对照组增加了 8%和 5%（P<0.05）。与对照组相比， challenged 组的体重增加减少（P<0.05）。与对照组相比，所有 challenged 组的体重增加均减少（P<0.05），即使采食量没有减少（通过方差协方差分析进行调整）。感染堆型艾美耳球虫、巨型艾美耳球虫、毒害艾美耳球虫或混合感染的肉鸡的采食量变化对体重增加的变化呈二次影响（P<0.05）。就孤立效应而言，挑战对采食量和体重增加的方差影响小于 1%。然而，效应的大小随艾美耳球虫种、动物年龄、性别和遗传品系而变化。一般来说，年龄效应优于挑战效应，表明挑战时的年龄对于确定艾美耳球虫感染的影响很重要。
