Abstract：
This study investigated the effects of feeding an amylase-enabled corn silage (ACS) on the performance and enteric gas emissions in lactating dairy cows. Following a 2-wk covariate period, 48 mid-lactation Holstein cows were assigned to 1 of 3 treatments in a 10-wk randomized complete block design experiment. Treatments were diets containing the same proportion of corn silage (40% of dietary DM) as follows: (1) a conventional hybrid corn silage control (CON), (2) ACS replacing the control silage (ADR), and (3) the ADR diet replacing soybean hulls with ground corn grain to achieve the same dietary starch concentration as CON (ASR). Control corn silage and ACS were harvested on the same day and contained 40.3% and 37.1% DM and (% of DM): 37.2% and 41.0% NDF and 37.1% and 30.0% starch, respectively. Enteric gas emissions were measured using the GreenFeed system. Two cows were culled due to health-related issues during the covariate period. Ruminal fluid was collected from 24 cows (8 per treatment) using the orogastric ruminal sampling technique. When compared with CON, cows fed ADR had increased DMI during experimental wk 3, 4, and 9, but treatment did not affect milk or ECM milk yields (39.0 kg/d on average; SEM = 0.89). Compared with CON, feed efficiency (per unit of milk, but not ECM) tended to be lower for ADR, whereas milk true protein concentration (a tendency) and yield were lower for ASR. Milk urea N was decreased by both ADR and ASR diets relative to CON. Compared with CON, daily CH4 emission and emission intensity were increased by ADR but not ASR. Total protozoal count tended to be increased by both diets formulated with ACS when compared with control corn silage. Total-tract digestibility of dietary NDF was greater for ASR, and that of ADF was greater for both ADR and ASR versus CON. The molar proportion of acetate (a tendency) and acetate-to-propionate ratio were increased by ADR, but not ASR, when compared with CON. Replacement of CON with ACS (having lower starch concentration) in the diet of dairy cows increased DMI during the initial weeks of the experiment, maintained ECM, tended to decrease feed efficiency, and increased enteric CH4 emissions, likely due to increased intake of digestible fiber, compared with CON.
摘要：
这项研究调查了饲喂淀粉酶启用的玉米青贮（ACS）对泌乳奶牛的性能和肠道气体排放的影响。在2周的协变量周期之后，在10周的随机完整区组设计实验中，将48只哺乳期中期的荷斯坦奶牛分配到3种处理中的1种。处理是含有相同比例的玉米青贮饲料（饮食DM的40％）的饮食如下：（1）常规杂交玉米青贮饲料对照（CON），（2）ACS取代控制青贮饲料（ADR），和（3）ADR日粮用磨碎的玉米粒代替大豆壳，以达到与CON（ASR）相同的日粮淀粉浓度。对照玉米青贮饲料和ACS在同一天收获，并含有40.3％和37.1％DM和（DM的％）：37.2％和41.0％NDF以及37.1％和30.0％淀粉，分别。使用GreenFeed系统测量肠内气体排放。在协变量期间，由于与健康相关的问题，两头母牛被淘汰。使用口胃瘤胃取样技术从24头母牛(每个处理8头)收集瘤胃液。与CON相比，饲喂ADR的奶牛在第3、4和9周的实验期间增加了DMI,但处理不影响牛奶或ECM牛奶产量(平均39.0kg/d;SEM=0.89).与CON相比,饲料效率(每单位牛奶，但不是ECM)的ADR倾向于较低，而ASR的牛奶真蛋白浓度(趋势)和产量较低。相对于CON，ADR和ASR饮食均降低了牛奶尿素N。与CON相比,ADR增加了每日CH4排放量和排放强度，而ASR不增加。与对照玉米青贮相比，用ACS配制的两种饮食都倾向于增加原生动物总数。ASR的饮食NDF的总道消化率更高，ADR和ASR的ADF比CON更大。ADR增加了乙酸盐的摩尔比例（趋势）和乙酸盐与丙酸盐的比例，但不是ASR,与CON相比。在实验的最初几周，用ACS（具有较低的淀粉浓度）在奶牛的日粮中替换CON会增加STI。维护的ECM，倾向于降低饲料效率，增加了肠道CH4的排放，可能是由于易消化纤维的摄入量增加，与CON相比。
