Fibre is essential to maintain healthy gut; however, energy demands of performance horses can be too high to be met by forages alone. Yeast may support the function of cellulolytic bacteria to digest fibre. The aim of this work was to determine the effect of an oral supplement (VistaEQ) containing 4% live yeast on the in vitro and in vivo digestibility of high-starch (HS) and high-fibre diets (HF). Eight ponies were used in a 4 × 4 Latin square design consisting of 4- × 19-day periods and four diets: HF, HF + yeast (HFY), HS and HS + yeast (HSY). In vivo apparent digestibility (AD) was estimated using total collection technique, and faecal particle size was measured using NASCO digestive analyser. Faeces from the ponies were subsequently used as an inoculum in ANKOM RF gas production system to assess fermentation kinetics in vitro. Each module contained 1 g of feed substrate DM in the following combinations: 50% grass hay and 50% alfalfa (HF_50 : 50) or concentrate (HS_50 : 50), and 75% grass hay and 25% alfalfa (HF_75 : 25) or concentrate (HS_75 : 25) with or without yeast. Yeast was able to induce more gas production from HF_75 : 25, HS_75 : 25 and HF_50 : 50 feed substrates incubated with respective faecal inoculum base. Yeast did not affect pH in vitro when the substrates were incubated in 50 : 50 ratio, while the pH was higher for HF_75 : 25 incubated with correspondent faecal inoculum compared to HS_75 : 25 and HSY_75 : 25. Yeast had no effects on ADF and CP AD of either diet. Yeast addition increased DM (HF: 0.2%, HS: 0.4%), organic matter (HF: 0.7%, HS: 1.3%), NDF (HF: 0.5%, HS: 1.5%), total detergent fibre (HF: 0.7%; HS: 0.4%) (P < 0.05) and also tended to increase hemicellulose AD (HF: 0.9%, HS: 1.2%) (P < 0.10). Faecal pH in vivo was higher for both HF diets compared to HS diet without yeast supplementation (P < 0.001, HF and HFY: 6.8; HS: 6.6, HSY: 6.7). However, no difference was observed in faecal pH when HSY was compared to both HF diets. Yeast had no effect on the size of the faecal particles (P > 0.05). Yeast increased in vitro gas production, suggesting more energy could be extracted from the feed, and the in vivo AD of some of the nutrients when HF and HS diets were fed.

纤维对于维持健康的肠道至关重要。但是，性能马匹的能量需求可能太高，无法仅靠饲草来满足。酵母可能支持纤维素分解细菌消化纤维的功能。这项工作的目的是确定含4％活酵母的口服补充剂（VistaEQ）对高淀粉（HS）和高纤维饮食（HF）的体外和体内消化率的影响。八个小马以4×4的拉丁方设计使用，包括4×19天的时间段和四种饮食：HF，HF +酵母（HFY），HS和HS +酵母（HSY）。体内表观消化率（AD使用总收集技术估算），并使用NASCO消化分析仪测量粪便粒径。随后，将小马的粪便用作ANKOM RF气体生产系统中的接种物，以评估其体外发酵动力学。每个模块包含以下组合的1 g饲料基质DM：50％的干草和50％的苜蓿（HF_50：50）或浓缩物（HS_50：50），以及75％的干草和25％的苜蓿（HF_75：25）或浓缩物（HS_75：25），含或不含酵母。酵母能够从分别与粪便接种物基质一起孵育的HF_75：25，HS_75：25和HF_50：50饲料底物中诱导更多的气体产生。酵母在体外不影响pH当底物以50:50的比例温育时，与相应的粪便接种物温育的HF_75：25的pH值高于HS_75：25和HSY_75：25。酵母对两种饮食的ADF和CP AD均无影响。酵母添加增加了DM（HF：0.2％，HS：0.4％），有机物（HF：0.7％，HS：1.3％），NDF（HF：0.5％，HS：1.5％），总洗涤剂纤维（HF：0.7 ％； HS：0.4％）（P＜0.05），并且还倾向于增加半纤维素AD（HF：0.9％，HS：1.2％）（P＜0.10）。与不添加酵母的HS饮食相比，两种HF饮食的体内粪便pH值均较高（P<0.001，HF和HFY：6.8; HS：6.6，HSY：6.7）。然而，当将HSY与两种HF饮食相比时，粪便pH没有观察到差异。酵母菌对粪便颗粒的大小没有影响（P > 0.05）。酵母增加了体外产气量，表明当饲喂HF和HS饲料时，可以从饲料中提取更多的能量，并且某些营养素在体内具有AD。