摘要
This study evaluated the effects of supplementing dry live yeast (LY; Saccharomyces cerevisiae) on in vitro gas production (IVGP) fermentation dynamics, pH, and CH4 concentration at 48 h, and in situ rumen parameters and digestibility of DM (DMD) and NDF (NDFD) of growing cattle during 3 feeding phases: grower (GRW) for 17 d (38% steamed-flaked corn; SFC), transition (TRANS) for 15 d (55.5% SFC: 1.2 Mcal/kg NEg), and finisher (FIN) for 13 d (73% SFC: 1.23 Mcal/kg NEg). Twenty British-crossbred, ruminally cannulated steers (183 kg ± 44 kg) 6 mo of age were blocked by weight into 5 pens containing Calan gate feeders and received a control (CON) diet (17.2% CP, 35.8% NDF, 86.7% DM) without LY on days −12 to 0. After that, animals were randomly assigned to treatments (TRT), 5 animals per TRT: CON or LY at inclusion rates of 5 g/d (LY1), 10 g/d (LY2), or 15 g/d (LY3) top dressed every morning at 0800 for 45 d. The DMD and NDFD were assessed during 7 separate collection days using in situ nylon bags containing 5 g of GRW, TRANS, or FIN diets, incubated at 1200 for 48 h. Protozoa counts (PC) were determined during 5 collection periods. Data were analyzed as a repeated measure within a randomized complete block design, assuming a random effect of the pen. For GRW, TRT altered the total gas production of the nonfiber carbohydrate (NFC; P = 0.045) and the fractional rate of degradation (kd) of the fiber carbohydrate (FC) pool (P = 0.001) in a cubic pattern (P ≤ 0.05): LY2 had the most gas production and fastest kd. TRT also influenced DMD (P = 0.035) and NDFD (P = 0.012) with LY2 providing the greatest digestibility. For TRANS, TRT tended to affect the NFC kd (P = 0.078) and influenced pH (P = 0.04) and DMD (P < 0.001) in which LY2 yielded the fastest kd, highest pH, and greatest DMD. For FIN, there was an effect of TRT on total gas production (P < 0.001) and kd (P = 0.004) of the NFC pool, FC kd (P = 0.012), in vitro CH4 concentration (P < 0.001), PC (P < 0.001), DMD (P = 0.039), and NDFD (P = 0.008). LY1 had the highest PC and provided the greatest DMD and NDFD. LY2 had the fastest kd of both the NFC and FC pools and had the least CH4 concentration. LY3 had the greatest NFC gas production. No specific dose–response pattern was observed, but 10 g/d provided the most beneficial result for all diets. We concluded that supplementation with LY affected IVGP as well as ruminal parameters and digestibilities.
摘要译文
本研究评估了补充干活酵母（LY；酿酒酵母对48 h体外产气（IVGP）发酵动力学，pH和CH 4浓度的影响，以及生长牛在三个饲喂阶段的瘤胃参数和DM（DMD）和NDF（NDFD）的消化率： （GRW）17 d（38％玉米片）； SFC），过渡（TRANS）进行15 d（55.5％SFC：1.2 Mcal / kg NE g）和整理剂（FIN）进行13 d（73％SFC：1.23 Mcal / kg NE g）。将20英磅杂交瘤胃插管ste牛皮（183公斤±44公斤），按体重6个月大，分成5支装有Calan门饲养器的围栏，并接受对照（CON）饮食（17.2％CP，35.8％NDF，86.7％DM） ）在第-12天至第0天不使用LY。之后，将动物随机分配至治疗（TRT），每个TRT：CON或LY 5只动物，其包涵率分别为5 g / d（LY1），10 g / d（LY2）或每天15:00 g / d（LY3）上衣45 d。使用包含5 g GRW，TRANS或FIN日粮的原位尼龙袋，在1200个条件下孵育48小时，在7个单独的收集日中对DMD和NDFD进行评估。在5个采集周期内测定原生动物计数（PC）。假设笔具有随机作用，则在随机完整块设计中将数据作为重复测量进行分析。对于GRW，TRT改变了非纤维碳水化合物（NFC）的总产气量。 P = 0.045），纤维碳水化合物（FC）池的降解分数（kd）（P = 0.001）呈立方模式（P≤0.05）：LY2的产气量最大，kd最快。 TRT还影响了DMD（P = 0.035）和NDFD（P = 0.012），其中LY2具有最大的消化率。对于TRANS，TRT倾向于影响NFC kd（P = 0.078），并影响pH（P = 0.04）和DMD（P <0.001），其中LY2产生最快的kd，最高的pH和最大的DMD。对于FIN，TRT对NFC池的总产气量（P <0.001）和kd（P = 0.004），FC kd（P = 0.012），体外CH 4浓度（P <0.001），PC有影响（P <0.001），DMD（P = 0.039）和NDFD（P = 0.008）。 LY1具有最高的PC，并提供最大的DMD和NDFD。 LY2在NFC和FC池中的kd最快，并且CH 4浓度最低。 LY3的NFC气体产量最高。没有观察到具体的剂量反应模式，但是10 g / d的剂量对所有饮食提供了最有益的结果。我们得出的结论是，添加LY影响IVGP以及瘤胃参数和消化率。
Caitlyn M Cagle [1]; Luiz Fernando D Batista [1]; Robin C Anderson [2]; Mozart A Fonseca [3]; Matt D Cravey [4]; Christine Julien [4]; Luis O Tedeschi [1]. Evaluation of different inclusion levels of dry live yeast impacts on various rumen parameters and in situ digestibilities of dry matter and neutral detergent fiber in growing and finishing beef cattle[J]. Journal of Animal Science, 2019,97(12): 4987-4998