INRA, UR83 Recherches Avicoles, F-37380 Nouzilly, France.
Poult Sci. 2011 Sep;90(9):1878-89. doi: 10.3382/ps.2010-01311.
Increased stocking densities are frequently reported to depress chicken growth performance, but the mechanisms behind this are not fully understood. This study was conducted to investigate the effects of stocking density on growth performance and digestive microbiota, known to be sensitive to environmental factors. Chickens were reared at 2 stocking densities, 12 or 17 birds/m(2). Growth performance was recorded between d 1 and 39, and litter was scored for quality on d 25, 31, and 37. Digestive microbiota was analyzed along the digestive tract (crop, ileum, ceca) of 3- and 6-wk-old chickens by using 2 molecular approaches: a qualitative method (fingerprinting by temporal temperature gradient gel electrophoresis) and a quantitative method (real-time PCR). An increase in stocking density was found to negatively affect the feed conversion ratio (+3.1%) and depress the daily BW gain of broilers (-5.5%) during the period from d 32 to 39 (P ≤ 0.05). Litter quality was reduced with the high stocking density as early as d 25. At 3 wk of age, stocking density strongly affected the fingerprint profiles of the bacterial community, with the highest modifications observed in the crop and ceca (R analysis of similarity = 0.77 and 0.69, respectively, P ≤ 0.05). At 6 wk of age, significant differences in the fingerprint profiles between the stocking densities appeared in the crop and ceca (R analysis of similarity = 0.52 and 0.27, respectively, P ≤ 0.05). The abundance of bacterial groups targeted by real-time PCR was affected by stocking density, but only to a limited extent. Because digestive microbiota may have consequences on the physiology of the digestive tract, its modification by an increase in stocking density may be involved in the reduced growth performance of the bird.
高密度饲养常被报道会抑制鸡的生长性能，但其中的机制尚不完全清楚。本研究旨在探究饲养密度对生长性能和消化微生物群的影响，因为后者对环境因素较为敏感。试验鸡饲养在 2 种饲养密度下，分别为 12 只/平方米和 17 只/平方米。从第 1 天到第 39 天记录生长性能，在第 25、31 和 37 天评估垫料质量。通过 2 种分子方法（时温梯度凝胶电泳指纹图谱和实时 PCR）分析 3 周龄和 6 周龄鸡消化道（嗉囊、回肠、盲肠）中的消化微生物群。结果表明，饲养密度增加会降低饲料转化率（提高 3.1%）和肉鸡的日增重（第 32 天至 39 天降低 5.5%，P ≤ 0.05）。高密度饲养从第 25 天起就降低了垫料质量。3 周龄时，饲养密度强烈影响了细菌群落的指纹图谱，在嗉囊和盲肠中观察到的变化最大（相似性 R 分析分别为 0.77 和 0.69，P ≤ 0.05）。6 周龄时，在嗉囊和盲肠中观察到饲养密度之间的指纹图谱存在显著差异（相似性 R 分析分别为 0.52 和 0.27，P ≤ 0.05）。实时 PCR 靶向的细菌群的丰度受到饲养密度的影响，但影响程度有限。由于消化微生物群可能对消化道的生理功能有影响，其高密度饲养的改变可能参与了鸡生长性能的降低。
