Abstract

Resistant starch (RS) is fermentable by gut microbiota and effectively modulates fecal short-chain fatty acid concentrations in pigs, mice, and humans. RS may have similar beneficial effects on the canine gut but has not been well studied. The objective of this study was to evaluate the effects of 0%, 1%, 2%, 3%, and 4% dietary RS (Hi-maize 260) on apparent total tract macronutrient digestibility, fecal characteristics, fermentative end-product concentrations, and microbiota of healthy adult dogs. An incomplete 5 × 5 Latin square design with seven dogs and five experimental periods was used, with each treatment period lasting 21 d (days 0 to 17 adaptation; days 18 to 21 fresh and total fecal collection) and each dog serving as its own control. Seven dogs (mean age = 5.3 yr; mean body weight = 20 kg) were randomly allotted to one of five treatments formulated to be iso-energetic and consisting of graded amounts of 100% amylopectin cornstarch, RS, and cellulose and fed as a top dressing on the food each day. All dogs were fed the same amount of a basal diet throughout the study, and fresh water was offered ad libitum. The basal diet contained 6.25% RS (dry matter [DM] basis), contributing approximately 18.3 g of RS/d based on their daily food intake (292.5 g DM/d). Data were evaluated for linear and quadratic effects using SAS. The treatments included 0%, 1%, 2%, 3%, and 4% of an additional RS source. Because Hi-maize 260 is approximately 40% digestible and 60% indigestible starch, the dogs received the following amounts of RS daily: 0% = 18.3 g (18.3 + 0 g), 1% = 20.1 g (18.3 + 1.8 g), 2% = 21.9 g (18.3 + 3.6 g), 3% = 23.7 g (18.3 + 5.4 g), and 4% = 25.5 g (18.3 + 7.2 g). Apparent total tract DM, organic matter, crude protein, fat, and gross energy digestibilities and fecal pH were linearly decreased (P < 0.05) with increased RS consumption. Fecal output was linearly increased (P < 0.05) with increased RS consumption. Fecal scores and fecal fermentative end-product concentrations were not affected by RS consumption. Although most of the fecal microbial taxa were not altered, Faecalibacterium were increased (P < 0.05) with increased RS consumption. The decrease in fecal pH and increase in fecal Faecalibacterium would be viewed as being beneficial to gastrointestinal health. Although our results seem to indicate that RS is poorly and/or slowly fermentable in dogs, the lack of observed change may have been due to the rather high level of RS contained in the basal diet.

中文翻译：

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分级膳食抗性淀粉浓度对健康成年犬的表观全道常量营养素消化率和粪便发酵终产物和微生物种群的影响

摘要

抗性淀粉（RS) 可被肠道微生物群发酵，并有效调节猪、小鼠和人类的粪便短链脂肪酸浓度。RS 可能对犬的肠道有类似的有益影响，但尚未得到充分研究。本研究的目的是评估 0%、1%、2%、3% 和 4% 日粮 RS（Hi-maize 260）对表观全道常量营养素消化率、粪便特征、发酵终产物浓度、和健康成年犬的微生物群。使用了一个不完整的 5 × 5 拉丁方设计，有七只狗和五个实验期，每个治疗期持续 21 天（第 0 到 17 天适应；第 18 到 21 天新鲜和总粪便收集），每只狗作为自己的对照. 七只狗（平均年龄 = 5.3 岁；平均体重 = 20 公斤）被随机分配到五种处理方法中的一种，这些处理方法是等能的，由分级量的 100% 支链淀粉玉米淀粉、R​​S 和纤维素组成，每天作为食物的追肥喂养。在整个研究过程中，所有狗都喂食相同量的基础饮食，并随意提供淡水。基础日粮含有 6.25% RS（干物质 [DM ] 基础），根据他们的每日食物摄入量（292.5 g DM/d）贡献大约 18.3 g RS/d。使用 SAS 评估数据的线性和二次效应。处理包括 0%、1%、2%、3% 和 4% 的额外 RS 源。因为 Hi-maize 260 大约有 40% 的可消化淀粉和 60% 的不可消化淀粉，狗每天接受以下量的 RS：0% = 18.3 g (18.3 + 0 g)，1% = 20.1 g (18.3 + 1.8 g)， 2% = 21.9 g (18.3 + 3.6 g)，3% = 23.7 g (18.3 + 5.4 g)，4% = 25.5 g (18.3 + 7.2 g)。表观总干物质、有机质、粗蛋白、脂肪、总能量消化率和粪便 pH 值随着 RS 消耗的增加而线性降低（P < 0.05）。排便量呈线性增加（P< 0.05) 随着 RS 消耗的增加。粪便评分和粪便发酵终产物浓度不受 RS 消耗的影响。虽然大多数粪便微生物分类群没有改变，但随着 RS 消耗的增加，粪杆菌增加（P < 0.05）。粪便 pH 值的降低和粪便中粪杆菌的增加将被视为对胃肠健康有益。尽管我们的结果似乎表明 RS 在狗中的发酵能力很差和/或发酵缓慢，但没有观察到的变化可能是由于基础饮食中含有相当高的 RS 水平。