摘要
Abstract (Summary)Feed additives include numerous classes of compounds that when fed to finishing beef cattle can alter rumen metabolism, prevent pathogen infections, and improve performance. Essential oils, monensin, tylosin, and ractopamine are feed additives with differing modes of action and performance responses dependent on numerous dietary and animal factors.A cattle finishing experiment and metabolism experiment were conducted to evaluate the performance and carcass response to specific essential oil mixtures (EOM) and explain the mechanistic mode of action of EOM. Compared to control, improved G:F was observed when EOM were fed in combination with tylosin and this response was equivocal to a diet supplemented with monensin and tylosin. Additionally, metabolism characteristics indicated greater acetate volatile fatty acid (VFA) concentration with a similar acetate:propionate ratio with EOM when compared to monensin.To determine the effectiveness of monensin and ractopamine in diets containing modified distillers grains plus solubles (MDGS), an individual steer trial was conducted. In a forage diet, monensin and MDGS were effective at improving steer performance or rumen fermentation characteristics. Ractopamine supplementation during a finisher phase increased performance with concomitant improvement in HCW. Addition of MDGS improved rumen fermentation characteristics with performance response improved slightly. Minimal rumen fermentation differences were observed when diets were supplemented with monensin or ractopamine.Three feeding trials with different corn processing methods were conducted to determine effectiveness of monensin and tylosin in diets containing wet distillers grains plus solubles (WDGS). An interaction between corn processing and WDGS was observed for performance with WDGS having a greater feeding value in diets containing dry-rolled and high-moisture corn compared to steam-flaked corn. Inclusion of monensin and tylosin in WDGS diets improved G:F and decreased liver abscesses compared to a WDGS diet without these feed additives regardless of corn processing method utilized.
摘要译文
摘要（摘要）饲料添加剂包括许多类，当喂到精加工肉牛可以改变瘤胃代谢，防止病菌感染，并提高性能的化合物。精油，莫能菌素，泰乐菌素和莱克多巴胺是饲料添加剂具有不同的操作和性能的响应依赖于众多的饮食和动物factors.A牛整理实验和代谢实验模式进行了评估性能和胴体响应于特定精油的混合物（EOM），并解释EOM的动作的机械方式。与对照组相比，提高了G：F的观察，当EOM与泰乐菌素组合喂食，这反应是模棱两可，以补充莫能和泰乐菌素饮食。此外，代谢特征表明更大乙酸挥发性脂肪酸（VFA）浓度具有相似的醋酸：丙酸比率相比monensin.To确定莫能在含改性酒糟加可溶饮食（目标）的效力和莱克多巴胺EOM，个人转向试验进行。在饲草饲料，莫能菌素和千年发展目标在改善转向性能或瘤胃发酵特性有效。在一个肥育阶段补充莱克多巴胺提高性能，在医护人员伴随改善。此外千年发展目标改善瘤胃发酵特性与性能响应略有改善。最小瘤胃观察发酵差异，当饲料被补充有与不同的玉米加工方法莫能菌素或ractopamine.Three饲养试验中进行，以确定莫能菌素和泰乐菌素在含有湿酒糟加可溶物（WDGS）日粮的有效性。性能观察到具有含干轧和高水分玉米饲料更大的饲用价值WDGS相比，蒸汽压片玉米的玉米加工和WDGS之间的相互作用。莫能菌素和泰乐菌素在WDGS日粮的改善纳入G：F和降低肝脓肿相比，WDGS饮食没有使用这些饲料添加剂，无论玉米加工方法。
Meyer, Nathan F.. Effects of feed additives in traditional corn diets and diets containing ethanol by-products in finishing beef cattle systems[D]. US: The University of Nebraska - Lincoln, 2008