Pinna Carlo, Vecchiato Carla Giuditta, Zaghini Giuliano, Grandi Monica, Nannoni Eleonora, Stefanelli Claudio, Biagi Giacomo
Department of Veterinary Medical Sciences, University of Bologna, via Tolara di Sopra 50, 40064, Ozzano Emilia, Italy.
Department for Life Quality Studies, University of Bologna, Corso d'Augusto 237, 47921, Rimini, Italy.
BMC Vet Res. 2016 Mar 12;12:53. doi: 10.1186/s12917-016-0672-1.
The present in vitro study investigated whether the utilization of fructooligosaccharides (FOS) may influence canine fecal microbial population in presence of diets differing in their protein content and digestibility. Fresh fecal samples were collected from five adult dogs, pooled, and incubated for 24 h with the undigested residue of three diets: 1, Low protein high digestibility diet (LP HD, crude protein (CP) 229 g/kg); 2, High protein high digestibility diet (HP HD, CP 304 g/kg); 3, High protein low digestibility diet (HP LD, CP 303 g/kg) that had been previously subjected to enzymatic digestion. In the in vitro fermentation study, there were six treatments: 1) LP HD; 2) HP HD 3) HP LD; 4) LP HD + FOS; 5) HP HD + FOS; 6) HP LD + FOS. Fructooligosaccharides were added at the final concentration of 1.5 g/L. Samples of fermentation fluid were collected at 6 and 24 h of incubation.
Values of pH were reduced by FOS at 6 and 24 h (P < 0.001); conversely, low protein digestibility and high dietary protein level resulted in higher pH at both sampling times (P < 0.001). At 24 h, FOS lowered ammonia (-10%; P < 0.001) and resulted (P < 0.05) in higher concentrations of total volatile fatty acids (VFA) (+43%), acetic acid (+14%), propionic acid (+75%) and n-butyric acid (+372%). Conversely, at 24 h, low protein digestibility resulted (P < 0.01) in lower concentrations of acetic acid (-26%), propionic acid (-37%) and total VFA (-21%). Putrescine concentrations were increased at 6 and 24 h of fermentation by low protein digestibility (+21 and 22%, respectively; P < 0.05) and FOS (+18 and 24%, respectively; P < 0.01). After 24 h of fermentation, high dietary protein level resulted in lower counts of lactobacilli and enterococci (-0.5 and -0.7 log cells/mL, respectively; P < 0.05) whereas low protein digestibility tended to increase counts of C. perfringens (+0.2 log cells/mL; P = 0.07).
Results from the present study showed that diets rich in protein may exert negative influences on the canine intestinal ecosystem, slightly increasing the presence of ammonia and reducing counts of lactobacilli and enterococci. Moreover, the presence of poorly digestible protein resulted in lower concentrations of VFA. Conversely, administration of FOS may improve metabolism of canine intestinal microbiota, reducing ammonia concentrations and enhancing VFA production.
本体外研究调查了在蛋白质含量和消化率不同的日粮存在的情况下，低聚果糖（FOS）的使用是否会影响犬类粪便微生物群落。从五只成年犬收集新鲜粪便样本，混合后与三种日粮的未消化残渣一起孵育24小时：1. 低蛋白高消化率日粮（LP HD，粗蛋白（CP）229 g/kg）；2. 高蛋白高消化率日粮（HP HD，CP 304 g/kg）；3. 高蛋白低消化率日粮（HP LD，CP 303 g/kg），这些日粮之前已进行酶消化。在体外发酵研究中，有六种处理方式：1）LP HD；2）HP HD；3）HP LD；4）LP HD + FOS；5）HP HD + FOS；6）HP LD + FOS。低聚果糖以1.5 g/L的终浓度添加。在孵育6小时和24小时时收集发酵液样本。
FOS在6小时和24小时时降低了pH值（P < 0.001）；相反，低蛋白消化率和高日粮蛋白水平在两个采样时间均导致较高的pH值（P < 0.001）。在24小时时，FOS降低了氨含量（-10%；P < 0.001），并导致（P < 0.05）总挥发性脂肪酸（VFA）浓度升高（+43%）、乙酸（+14%）、丙酸（+75%）和正丁酸（+372%）浓度升高。相反，在24小时时，低蛋白消化率导致（P < 0.01）乙酸（-26%）、丙酸（-37%）和总VFA（-21%）浓度降低。在发酵6小时和24小时时，低蛋白消化率（分别为+21%和+22%；P < 0.05）和FOS（分别为+18%和+24%；P < 0.01）使腐胺浓度升高。发酵24小时后，高日粮蛋白水平导致乳酸杆菌和肠球菌数量减少（分别为-0.5和-0.7 log细胞/mL；P < 0.05），而低蛋白消化率倾向于增加产气荚膜梭菌数量（+0.2 log细胞/mL；P = 0.07）。
本研究结果表明，富含蛋白质的日粮可能对犬类肠道生态系统产生负面影响，略微增加氨的含量并减少乳酸杆菌和肠球菌数量。此外，难消化蛋白质的存在导致VFA浓度降低。相反，给予FOS可能改善犬类肠道微生物群的代谢，降低氨浓度并提高VFA产量。
