Pickett Autumn T, Cooke Reinaldo F, de Souza Izadora S, de Souza Willian A, Monteiro Guilherme A, do Prado Mykael B, Gouvêa Vinícius N, Araujo Rafael C, Mackey Shea J
Department of Animal Science - Texas A&M University, College Station, TX 77843, USA.
Texas A&M AgriLife Research and Extension Center, Amarillo, TX 79106, USA.
Transl Anim Sci. 2025 Aug 19;9:txaf103. doi: 10.1093/tas/txaf103. eCollection 2025.
This experiment evaluated the effects of supplementing yeast culture ( ) on in situ ruminal degradability, rumen fermentation and microbiota responses of heifers consuming a forage-based diet. Twelve ruminally-cannulated Angus-influenced heifers were ranked by body weight ( 180 ± 4 kg) and assigned to 4 groups of 3 heifers each. Groups were enrolled in a replicated 3 × 3 Latin square design containing 3 periods of 21 d and 14-d washout intervals. Groups were assigned to receive no YC (), or 1.5 g of YC/100 kg of heifer BW () or 3.0 g of YC/100 kg of heifer BW (). During each period, heifers (n = 12/treatment) were housed in individual pens and offered water and bermudagrass hay () for ad libitum consumption, in addition to 650 g/d (as-fed basis) of a corn-based concentrate. The YC was mixed daily with the concentrate during each period (d 0 to 21). Ruminal in situ disappearance of forage dry matter () and neutral detergent fiber () were evaluated by incubating polyester bags with 4 g of dietary hay on d 17 for 96 h. Rumen fluid samples were collected on d 0, 8, and 16, in a manner that the final collection (d 16) did not interfere with in situ procedures on d 17. Apparent total-tract digestibility () of nutrients was calculated using fecal samples collected every 12-h from d 17 to 21. Data were analyzed using orthogonal contrasts (linear and quadratic) with heifer as the experimental unit. Feed intake was not affected (≥ 0.14) by treatments. Inclusion of YC linearly increased (≤ 0.04) propionate and iso-butyrate concentrations in the rumen fluid, and tended (≤ 0.09) to increase acetate and total volatile fatty acid () concentrations. Inclusion of YC linearly decreased (= 0.03) the relative abundance of the bacterial genus , and linearly increased (= 0.04) genera Shannon diversity index in the rumen fluid. Inclusion of YC linearly increased (≤ 0.05) ruminal disappearance rate of hay DM and NDF, but did not affect (≥ 0.40) degradability of DM and NDF. Inclusion of YC linearly increased (≤ 0.05) aTTD of starch and NDF. Inclusion of YC linearly increased (= 0.04) heifer average daily gain and gain:feed (). Collectively, supplementing 1.5 or 3.0 g of YC/100 kg of BW linearly enhanced utilization of dietary nutrients and production of ruminal VFA in beef heifers consuming a forage-based diet.
本试验评估了添加酵母培养物（ ）对采食以粗饲料为主日粮的小母牛瘤胃原位降解率、瘤胃发酵及微生物群反应的影响。12头安装了瘤胃瘘管的安格斯杂交小母牛按体重（180 ± 4 kg）排序，分为4组，每组3头。试验采用重复的3 × 3拉丁方设计，包括3个21天的周期和14天的洗脱期。各组分别饲喂不添加YC（ ）、1.5 g YC/100 kg小母牛体重（ ）或3.0 g YC/100 kg小母牛体重（ ）。在每个周期内，小母牛（每组n = 12头）单独饲养在栏舍中，除了每天提供650 g（风干基础）玉米型精料外，还自由采食水和百慕大干草（ ）。在每个周期（第0至21天），YC每天与精料混合。通过在第17天用聚酯袋孵育4 g日粮干草96小时，评估粗饲料干物质（ ）和中性洗涤纤维（ ）的瘤胃原位消失率。在第0、8和16天采集瘤胃液样本，确保最后一次采集（第16天）不干扰第17天的原位试验。利用第17至21天每12小时采集的粪便样本计算养分的表观全肠道消化率（ ）。以小母牛作为试验单位，采用正交对比（线性和二次）分析数据。处理对采食量无影响（≥ 0.14）。添加YC使瘤胃液中丙酸和异丁酸浓度呈线性增加（≤ 0.04），乙酸和总挥发性脂肪酸（ ）浓度有增加趋势（≤ 0.09）。添加YC使瘤胃液中细菌属 的相对丰度呈线性下降（= 0.03），香农多样性指数呈线性增加（= 0.04）。添加YC使干草干物质和中性洗涤纤维的瘤胃消失率呈线性增加（≤ 0.05），但对干物质和中性洗涤纤维的降解率无影响（≥ 0.40）。添加YC使淀粉和中性洗涤纤维的表观全肠道消化率呈线性增加（≤ 0.05）。添加YC使小母牛平均日增重和增重：饲料比（ ）呈线性增加（= 0.04）。总体而言，添加1.5或3.0 g YC/100 kg体重可线性提高采食以粗饲料为主日粮的肉用小母牛对日粮养分的利用率和瘤胃挥发性脂肪酸的生成。
