Teagasc Food Research Centre, Dublin 15, Ireland; Institute of Food and Health, University College Dublin, Dublin 4, Ireland.
J Appl Microbiol. 2014 Sep;117(3):876-81. doi: 10.1111/jam.12580. Epub 2014 Jul 2.
The objectives of this study were the following: (i) to investigate if Campylobacter negative flocks at first thinning remain negative at second thinning; (ii) to determine if the caecal counts in birds infected during first thinning remain lower than in birds that were positive at first thinning; and (iii) to determine if reducing the time between first and second thinning to a maximum of 4 days would reduce both the incidence and prevalence of broiler caecal contamination.
Twenty-two flocks were tested at first and second thinning using ISO methodologies. Of the 14 that had a 4-day duration between first and second thinning, nine flocks were Campylobacter negative at first thinning. By second thinning, all 14 flocks were positive and Campylobacter counts ranged from 5·5 to 6·6 log(10) CFU g(-1) regardless of the status at first thinning. The other eight flocks were all Campylobacter positive at first thinning with counts ranging from 0·8 to 6·1 log(10) CFU g(-1) which increased to 5·1 to 6·9 log(10) CFU g(-1) by second thinning (3-10 days). PCR speciation and MLST genotyping suggested the majority of isolates were Camp. jejuni belonging to STs 257, 814, 6763 and 6764.
It was concluded that; thinning introduces Campylobacter into broiler flocks; caecal counts in birds at second thinning are similar, regardless of flock status at first thinning and reducing the time between first and second thinning to a maximum of 4 days is not an effective control strategy.
This study informs Campylobacter control strategy at primary production, suggesting all post-first thinning broilers should be treated as 'high risk' regardless of Campylobacter status at first thinning or duration between first and second thinning.
本研究的目的如下：（i）调查首次间苗时阴性的空鸡群在第二次间苗时是否仍为阴性；（ii）确定首次间苗时感染的鸡群的盲肠计数是否仍低于首次间苗时呈阳性的鸡群；（iii）确定将首次间苗和第二次间苗之间的时间间隔缩短至最长 4 天是否会降低肉鸡盲肠污染的发生率和流行率。
使用 ISO 方法对 22 个鸡群在首次和第二次间苗时进行了检测。在 14 个首次间苗和第二次间苗之间的时间间隔为 4 天的鸡群中，9 个鸡群在首次间苗时为阴性。到第二次间苗时，所有 14 个鸡群均为阳性，无论首次间苗时的状态如何，盲肠计数范围为 5.5 至 6.6 log(10)CFU g(-1)。其他 8 个鸡群在首次间苗时均为阳性，盲肠计数范围为 0.8 至 6.1 log(10)CFU g(-1)，到第二次间苗时增加到 5.1 至 6.9 log(10)CFU g(-1)（3-10 天）。PCR 种特异性和 MLST 基因分型表明，大多数分离株为属于 STs 257、814、6763 和 6764 的空肠弯曲菌。
本研究得出结论：间苗将空肠弯曲菌引入肉鸡鸡群；第二次间苗时鸡群的盲肠计数相似，无论首次间苗时的鸡群状态如何，并且将首次间苗和第二次间苗之间的时间间隔缩短至最长 4 天不是一种有效的控制策略。
本研究为初级生产中的空肠弯曲菌控制策略提供了信息，表明无论首次间苗时的空肠弯曲菌状态或首次间苗和第二次间苗之间的时间间隔如何，所有第二次间苗后的肉鸡都应被视为“高风险”。
