Water quality is critical for egg production and animal health in commercial layer housing systems. To investigate microbial contamination in nipple drinking system in layer houses, the bacterial abundance and communities in water pipes and V-troughs on different tiers (e.g., 1st, 3rd, 5th, and 7th tiers) of a layer house with 8 overlapping cage tiers were determined using qRT-PCR and 16S rRNA sequencing. The water bacterial abundance (i.e., genome 16S rDNA copy number, WBCN) in water pipes and V-troughs did not significantly differ among tiers, but they were 46.77 to 1905.46 times higher in V-troughs than that in water pipes (P < 0.05) for each tier. Illumina sequencing obtained 1,746,303 effective reads from 24 water samples in V-troughs of 4 tiers (six samples from each tier). Taxonomic analysis indicated that the 1st and 5th tiers were predominated by Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, while the 3rd and 7th tiers were predominated by Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria. The top four genera were Acinetobacter, Streptococcus, Rothia and Comamonas among measured tiers. The high bacterial abundance and bacterial OTUs of water in the V-troughs reflect poor water quality, which may adversely affect growth and health of laying hens. Therefore, it is suggested that water quality in the V-tough should be checked more frequently in commercial layer houses.

水质对于商品蛋鸡舍系统中的产蛋量和动物健康至关重要。为了调查蛋鸡乳头饮水系统中的微生物污染，8 层重叠的蛋鸡舍不同层级（如 1、3、5 和 7 层）的水管和 V 型槽中的细菌丰度和群落为使用 qRT-PCR 和 16S rRNA 测序确定。水管和V型槽中水细菌丰度（即基因组16S rDNA拷贝数，WBCN）各层级间差异不显着，但V型槽比水管高46.77～1905.46倍（P < 0.05) 对于每一层。Illumina 测序从 4 层 V 型槽（每层 6 个样本）中的 24 个水样中获得了 1,746,303 个有效读数。分类学分析表明，第1和第5层以Proteobacteria、Actinobacteria、Firmicutes和Bacteroidetes为主，而第3和第7层以Proteobacteria、Firmicutes、Bacteroidetes和Actinobacteria为主。顶部4个属是不动杆菌属，链球菌属，Rothia和丛毛单胞测量层之间。V 型槽中水的高细菌丰度和细菌 OTU 反映了水质差，这可能会对蛋鸡的生长和健康产生不利影响。因此，建议商品蛋鸡舍多检查V型槽内的水质。