Hill's Pet Nutrition, Inc, Topeka, KS, USA.
Department of Grain Science and Industry, Kansas State University, Manhattan, KS, USA.
J Nutr. 2021 Dec 3;151(12):3637-3650. doi: 10.1093/jn/nxab308.
Relative levels of dietary protein and carbohydrate intake influence microbiota and their functional capabilities, but the effect has not been well documented in cats.
The impact of 3 foods with different protein:carbohydrate ratios on the gut microbiota and functional attributes in healthy adult cats was evaluated.
Male and female cats (n = 30; mean age: 5.1 y; mean body weight: 5.26 kg) were fed 1 of 3 foods [P28 (28.3% protein, dry matter basis), P35 (35.1%), and P55 (54.8%)] for 90 d in a Williams Latin Square design. Each food had a 1:1 ratio of animal (dried chicken) to plant (pea) protein; protein replaced carbohydrate as protein level increased. Fecal microbiota and their functional capability were assessed with 16S sequencing and the Kyoto Encyclopedia of Genes and Genomes database, respectively.
Fecal pH, ammonia, and branched-chain fatty acids (BCFAs) were higher when cats consumed P55 food than when they consumed P28 and P35. Clear separation of samples between P28 and P55 based on bacterial genera was observed, with partitioning into saccharolytic and proteolytic functions, respectively. Significantly higher α diversity was seen with P55 than with P28 and P35. Amino acid metabolism, mucin foraging pathways, and urea metabolism were higher with P55 than with P28, whereas feces from cats fed P28 had higher concentrations of carbohydrate-active enzymes and enzymes involved in SCFA pathways than with P55. Bacterial genera that showed positive associations with amino acid catabolism also showed positive associations with mucin degradation.
Despite higher protein digestibility and less protein arriving to the colon, when healthy adult cats consumed the highest level of protein (P55), their gut microbiota exhibited higher mucin glycan foraging and amino acid metabolism, leading to higher fecal pH, ammonia, and BCFAs. This is likely due to lower availability of carbohydrate substrates and dietary fiber as protein replaced carbohydrate in the food.
膳食蛋白质和碳水化合物的相对摄入量会影响微生物组及其功能特性，但这在猫身上尚未得到充分证实。
评估 3 种不同蛋白质：碳水化合物比例的食物对健康成年猫肠道微生物组和功能特性的影响。
将 30 只雄性和雌性猫（平均年龄：5.1 岁；平均体重：5.26kg）随机分为 3 组，分别喂食 3 种食物[P28（蛋白质 28.3%，干物质基础）、P35（蛋白质 35.1%）和 P55（蛋白质 54.8%）]，为期 90d，采用威廉斯拉丁方设计。每种食物的动物（干鸡肉）与植物（豌豆）蛋白的比例均为 1:1；随着蛋白质水平的增加，用蛋白质替代碳水化合物。分别通过 16S 测序和京都基因与基因组百科全书数据库评估粪便微生物组及其功能能力。
与 P28 和 P35 相比，P55 组猫的粪便 pH 值、氨和支链脂肪酸（BCFA）更高。根据细菌属对 P28 和 P55 之间的样本进行了明显的分离，分别与糖解和蛋白水解功能相关。与 P28 和 P35 相比，P55 组的 α 多样性显著更高。与 P28 相比，P55 组的氨基酸代谢、粘蛋白觅食途径和尿素代谢更高，而 P28 组猫的粪便中碳水化合物活性酶和参与短链脂肪酸（SCFA）途径的酶的浓度更高。与氨基酸代谢呈正相关的细菌属也与粘蛋白降解呈正相关。
尽管蛋白质消化率更高，到达结肠的蛋白质更少，但当健康成年猫摄入最高水平的蛋白质（P55）时，其肠道微生物组表现出更高的粘蛋白聚糖觅食和氨基酸代谢，导致粪便 pH 值、氨和支链脂肪酸更高。这可能是由于食物中蛋白质替代碳水化合物，导致碳水化合物底物和膳食纤维的可用性降低。
