Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan Province, P.R. China; College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, Hunan Province, P.R. China.
Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan Province, P.R. China.
J Dairy Sci. 2022 Jan;105(1):231-241. doi: 10.3168/jds.2021-20165. Epub 2021 Oct 23.
The physiological function of the reticulorumen plays an essential role in ruminant nutrition, and detailed knowledge of rumen motility can further advance understanding of ruminant nutrition and physiology. Rumen motility was simulated by setting different stirrer rotation speeds in a rumen simulation technique (RUSITEC) system. The aim of this study was to investigate the effects of rotation speeds on rumen fermentation, saturation factor of dissolved gases, hydrogen (H) and methane (CH) emissions, microbial protein synthesis, and selected microbial population using RUSITEC. The experiment was performed according to a balanced 3 × 3 Latin square design, and each period included 7 d for adaptation and 3 d for sampling. Three motility treatments included 5, 15, and 25 rpm rotation speeds. Daily total gas and H and CH emissions had quadratic responses to the increasing rotation speed and were highest at 15 rpm. Quadratic and linear responses (highest at 5 rpm) to increasing rotation speed were observed for saturation factors of H and CH, liquid-dissolved H and CH concentrations, and headspace concentration of H in the gas phase, whereas increasing rotation speed linearly decreased saturation factors of CO and liquid-dissolved CO concentration. Quadratic and linear responses to increasing rotation speed were observed for molar percentages of acetate, ammonia, and microbial protein concentration, whereas increasing rotation speed quadratically increased pH and decreased total volatile fatty acid concentration and acetate-to-propionate ratio. The 15-rpm rotation speed had the highest values of total volatile fatty acids, acetate molar percentage, and microbial protein concentration. Quadratic and linear responses to increasing rotation speed were observed for copy numbers of solid-associated fungi and fluid-associated bacteria, fungi, and protozoa, while increasing rotation speed linearly increased copy numbers of solid-associated protozoa. Rotation at 15 rpm increased populations of fungi and protozoa in the solid rumen contents and the population of bacteria and fungi in the liquid rumen contents. In summary, this study provides insights on the biofunction of proper rumen motility (i.e., at a rotation speed of 15 rpm), such as improving feed fermentation, increasing gas emissions with decreased dissolved gas concentrations and saturation factors, and promoting microbial colonization and microbial protein synthesis, although further increase in rotation speed (i.e., to 25 rpm) decreases feed fermentation and microbial protein synthesis.
反刍动物营养生理学的功能主要体现在反刍胃中，详细了解反刍胃的运动可以进一步促进反刍动物营养生理学的发展。通过在反刍模拟技术（RUSITEC）系统中设置不同的搅拌器转速，可以模拟反刍胃运动。本研究旨在利用 RUSITEC 研究转速对瘤胃发酵、溶解气体饱和度因子、氢气（H）和甲烷（CH）排放、微生物蛋白合成以及选择微生物种群的影响。该实验按照平衡 3×3 拉丁方设计进行，每个周期包括 7 天适应期和 3 天采样期。三个运动处理包括 5、15 和 25 rpm 的转速。总气体日排放量、H 和 CH 的日排放量与转速呈二次曲线关系，在 15 rpm 时最高。H 和 CH 的饱和度因子、液体溶解 H 和 CH 浓度、气相中 H 的顶空浓度呈二次曲线关系（在 5 rpm 时最高），而 CO 和液体溶解 CO 浓度的饱和度因子随转速的增加而线性降低。乙酸、氨和微生物蛋白浓度的摩尔百分比与转速呈二次曲线关系，而总挥发性脂肪酸浓度和乙酸/丙酸比随转速的增加而呈二次曲线关系。pH 值随转速的增加而降低，15 rpm 时的总挥发性脂肪酸、乙酸摩尔百分比和微生物蛋白浓度最高。固相中真菌和细菌、真菌和原生动物的数量与转速呈二次和线性关系，而固相中原生动物的数量随转速的增加而呈线性增加。转速为 15 rpm 时，可增加固体瘤胃内容物中真菌和原生动物的数量以及液体瘤胃液中细菌和真菌的数量。总之，本研究为适当的反刍胃运动（即转速为 15 rpm）的生物功能提供了新的认识，如改善饲料发酵、增加气体排放，降低溶解气体浓度和饱和度因子，促进微生物定植和微生物蛋白合成，尽管进一步提高转速（即 25 rpm）会降低饲料发酵和微生物蛋白合成。
