Data_Sheet_1_Effects of Zinc Source and Enzyme Addition on the Fecal Microbiota of Dogs.docx

Supplemental zinc from organic sources has been suggested to be more bioavailable than inorganic ones for dog foods. However, the bioavailability of zinc might be affected by dietary constituents such as phytates. The present study aimed to evaluate the effects of two zinc sources (zinc sulfate and zinc proteinate) and the addition of a multi-enzymatic complex from the solid-state fermentation of Aspergillus niger on end-products of fecal fermentation and fecal microbiota of adult Beagles fed a high-phytate diet. The experimental design consisted of three 4 × 4 Latin Squares with a 2 × 2 factorial arrangement of treatments (n = 12 Beagles), with four periods and four diets: zinc sulfate without (IZ) or with (IZ +) enzyme addition, and zinc proteinate without (OZ) or with (OZ +) enzyme addition. Enzyme addition significantly affected Faith’s phylogenetic diversity index, whereas zinc source did not affect either beta or alpha diversity measures. Linear discriminant analysis effect size detected nine taxa as markers for organic zinc, 18 for inorganic source, and none for enzyme addition. However, with the use of a negative binomial generalized linear model, further effects were observed. Organic zinc was associated with a significantly higher abundance of Firmicutes and lower Proteobacteria and Bacteroidetes, although at a genus level, the response varied. The DNA abundance of Clostridium cluster I, Clostridium cluster XIV, Campylobacter spp., Ruminococcaceae, Turicibacter, and Blautia was significantly higher in dogs fed IZ and IZ + diets. Higher abundance of genus Lactobacillus was observed in dogs fed enzyme-supplemented diets. End-products of fecal fermentation were not affected by zinc source or enzymes. An increase in some taxa of the phyla Actinobacteria and Firmicutes was observed in feces of dogs fed organic zinc with enzyme addition but not with inorganic zinc. This study fills a gap in knowledge regarding the effect of zinc source and enzyme addition on the fecal microbiota of dogs. An association of zinc bioavailability and bacteria abundance is suggested, but the implications for the host (dog) are not clear. Further studies are required to unveil the effects of the interaction between zinc sources and enzyme addition on the fecal microbial community.

有研究表明，犬粮中添加的有机锌相较于无机锌具有更高的生物利用度。然而，锌的生物利用度可能会受到植酸盐等膳食成分的影响。本研究旨在评估两种锌源——硫酸锌（zinc sulfate）与锌蛋白盐（zinc proteinate），以及添加由黑曲霉（Aspergillus niger）固态发酵制备的复合酶制剂，对饲喂高植酸盐日粮（high-phytate diet）的成年比格犬粪便发酵终产物与粪便微生物群（fecal microbiota）的影响。本实验采用3个4×4拉丁方设计（Latin Squares），结合2×2因子处理安排（n=12只比格犬），共设置4个试验阶段与4种日粮：无酶添加硫酸锌组（IZ）、加酶添加硫酸锌组（IZ+）、无酶添加锌蛋白盐组（OZ）以及加酶添加锌蛋白盐组（OZ+）。复合酶添加显著影响了费思系统发育多样性指数（Faith’s phylogenetic diversity index），而锌源对α多样性与β多样性指标均无显著影响。线性判别分析效应量（Linear discriminant analysis effect size）检测到9个分类单元作为有机锌组的生物标志物，18个作为无机锌组的生物标志物，而复合酶添加组未检测到相关标志物。不过，通过负二项广义线性模型（negative binomial generalized linear model）分析，还观测到了更多的效应。有机锌组的粪便菌群中，厚壁菌门（Firmicutes）的相对丰度显著升高，而变形菌门（Proteobacteria）与拟杆菌门（Bacteroidetes）的相对丰度显著降低，但在属水平上，菌群的响应存在差异。饲喂IZ与IZ+日粮的比格犬，其粪便中梭菌簇I（Clostridium cluster I）、梭菌簇XIV（Clostridium cluster XIV）、弯曲杆菌属（Campylobacter spp.）、瘤胃球菌科（Ruminococcaceae）、图里杆菌属（Turicibacter）以及布劳特氏菌属（Blautia）的DNA丰度显著升高。饲喂添加复合酶日粮的比格犬，其粪便中乳酸杆菌属（Lactobacillus）的相对丰度显著升高。粪便发酵终产物未受锌源或复合酶添加的影响。饲喂添加复合酶的有机锌日粮的比格犬，其粪便中放线菌门（Actinobacteria）与厚壁菌门（Firmicutes）的部分分类单元丰度显著升高，而饲喂无机锌加酶日粮的比格犬未出现该现象。本研究填补了锌源与复合酶添加对犬粪便微生物群影响相关研究的认知空白。研究提示锌生物利用度与细菌丰度存在关联，但该关联对宿主（犬）的生理意义尚不明确。未来仍需开展进一步研究，以阐明锌源与复合酶添加之间的交互作用对犬粪便微生物群落的影响。