Department of Animal Science, The Pennsylvania State University, University Park 16802.
Department of Animal Science, The Pennsylvania State University, University Park 16802; School of Veterinary Medicine, University of California, Davis, Tulare 93274.
J Dairy Sci. 2021 Sep;104(9):9827-9841. doi: 10.3168/jds.2021-20251. Epub 2021 Jul 10.
This study investigated the effects of an amylase-enabled corn silage on lactational performance, enteric CH emission, and rumen fermentation of lactating dairy cows. Following a 2-wk covariate period, 48 Holstein cows were blocked based on parity, days in milk, milk yield (MY), and CH emission. Cows were randomly assigned to 1 of 2 treatments in an 8-wk randomized complete block design experiment: (1) control corn silage (CON) from an isogenic corn without α-amylase trait and (2) Enogen hybrid corn (Syngenta Seeds LLC) harvested as silage (ECS) containing a bacterial transgene expressing α-amylase (i.e., amylase-enabled) in the endosperm of the grain. The ECS and CON silages were included at 40% of the dietary dry matter (DM) and contained, on average, 43.3 and 41.8% DM and (% DM) 36.7 and 37.5% neutral detergent fiber, and 36.1 and 33.1% starch, respectively. Rumen samples were collected from a subset of 10 cows using the ororuminal sampling technique on wk 3 of the experimental period. Enteric CH emission was measured using the GreenFeed system (C-Lock Inc.). Dry matter intake (DMI) was similar between treatments. Compared with CON, MY (38.8 vs. 40.8 kg/d), feed efficiency (1.47 vs. 1.55 kg of MY/kg of DMI), and milk true protein (1.20 vs. 1.25 kg/d) and lactose yields (1.89 vs. 2.00 kg/d) were increased, whereas milk urea nitrogen (14.0 vs. 12.7 mg/dL) was decreased, with the ECS diet. No effect of treatment on energy-corrected MY (ECM) was observed, but a trend was detected for increased ECM feed efficiency (1.45 vs. 1.50 kg of ECM/kg of DMI) for cows fed ECS compared with CON-fed cows. Daily CH emission was not affected by treatment, but emission intensity was decreased with the ECS diet (11.1 vs. 10.3 g/kg of milk, CON and ECS, respectively); CH emission intensity on ECM basis was not different between treatments. Rumen fermentation, apart from a reduced molar proportion of butyrate in ECS-fed cows, was not affected by treatment. Apparent total-tract digestibility of nutrients and urinary and fecal nitrogen excretions, apart from a trend for increased DM digestibility by ECS-fed cows, were not affected by treatment. Overall, ECS inclusion at 40% of dietary DM increased milk, milk protein, and lactose yields and feed efficiency, and tended to increase ECM feed efficiency but had no effect on ECM yield in dairy cows. The increased MY with ECS led to a decrease in enteric CH emission intensity, compared with the control silage.
本研究旨在探讨添加淀粉酶的玉米青贮对泌乳奶牛泌乳性能、肠道 CH 排放和瘤胃发酵的影响。在 2 周的协变量期后，根据胎次、泌乳天数、产奶量（MY）和 CH 排放量，将 48 头荷斯坦奶牛分为两组。采用 8 周随机完全区组设计试验，将奶牛随机分为 2 种处理之一：（1）对照玉米青贮（CON）来自无 α-淀粉酶特性的同基因玉米，（2）Enogen 杂交玉米（Syngenta Seeds LLC）收获为青贮（ECS），其中含有在谷物胚乳中表达α-淀粉酶（即淀粉酶启用）的细菌转基因。ECS 和 CON 青贮分别占日粮干物质（DM）的 40%，平均 DM 含量分别为 43.3%和 41.8%，中性洗涤纤维（DM）分别为 36.7%和 37.5%，淀粉分别为 36.1%和 33.1%。在实验期第 3 周，采用瘤胃取样技术从 10 头奶牛中采集瘤胃液样本。使用 GreenFeed 系统（C-Lock Inc.）测量肠道 CH 排放。两种处理之间的干物质采食量（DMI）相似。与 CON 相比，产奶量（38.8 与 40.8 kg/d）、饲料效率（1.47 与 1.55 kg MY/kg DMI）、乳真蛋白（1.20 与 1.25 kg/d）和乳糖产量（1.89 与 2.00 kg/d）增加，而乳尿素氮（14.0 与 12.7 mg/dL）降低，ECS 日粮。处理对能量校正的产奶量（ECM）没有影响，但 ECS 组的 ECM 饲料效率（1.45 与 1.50 kg ECM/kg DMI）呈增加趋势。每日 CH 排放不受处理影响，但 ECS 日粮降低了 CH 排放强度（11.1 与 10.3 g/kg 牛奶，CON 和 ECS）；基于 ECM 的 CH 排放强度在处理之间没有差异。除了 ECS 组奶牛丁酸摩尔比例降低外，瘤胃发酵不受处理影响。除了 ECS 组奶牛 DM 消化率呈增加趋势外，养分的表观全肠道消化率和尿氮、粪氮排泄不受处理影响。总体而言，日粮中添加 40%的 ECS 提高了牛奶、乳蛋白和乳糖的产量和饲料效率，并趋于提高 ECM 饲料效率，但对 ECM 产量没有影响。与对照青贮相比，ECS 的使用增加了产奶量，降低了肠道 CH 排放强度。
