Agricultural and Biosystems Engineering, North Dakota State University, Fargo, North Dakota 58108, USA.
Carrington Research Extension Center, North Dakota State University, Carrington, North Dakota, USA.
J Air Waste Manag Assoc. 2013 Dec;63(12):1457-68. doi: 10.1080/10962247.2013.831384.
Greenhouse gas (GHG) emissions from concentrated animal feeding operations vary by stage of production and management practices. The objective of this research was to study the effect of two dietary crude protein levels (12 and 16%) fed to beef steers in pens with or without corn stover bedding. Manure characteristics and GHG emissions were measured from feedlot pen surfaces. Sixteen equal-sized feedlot pens (19 x 23 m) were used. Eight were bedded approximately twice a week with corn stover and the remaining eight feedlot pens were not bedded. Angus steers (n = 138) were blocked by live weights (lighter and heavier) with 7 to 10 animals per pen. The trial was a 2 x 2 factorial design with factors of two protein levels and two bedding types (bedding vs. non bedding), with four replicates. The study was conducted from June through September and consisted of four -28-day periods. Manure from each pen was scrapped once every 28 days and composite manure samples from each pen were collected. Air samples from pen surfaces were sampled in Tedlar bags using a Vac-U-Chamber coupled with a portable wind tunnel and analyzed with a greenhouse gas gas chromatograph within 24 hr of sampling. The manure samples were analyzed for crude protein (CP), total nitrogen (TN), ammonia (NH3), total volatile fatty acid (TVFA), total carbon (TC), total phosphorus (TP), and potassium (K). The air samples were analyzed for methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) concentrations. The concentration of TN was significantly higher (p < 0.05) in manure from pens with cattle fed the high protein diets. The volatile fatty acids (VFAs) such as acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids concentrations were similar across both treatments. There were no significant differences in pen surface GHG emissions across manure management and dietary crude protein levels.
集约化养殖场的温室气体（GHG）排放因生产阶段和管理实践而异。本研究的目的是研究在有或没有玉米秸秆垫料的畜栏中，两种不同粗蛋白水平（12%和 16%）的日粮对肉牛的影响。从肥育畜栏表面测量粪便特性和温室气体排放。使用了 16 个大小相等的肥育畜栏（19 x 23 米）。其中 8 个畜栏大约每周两次用玉米秸秆垫料，其余 8 个畜栏没有垫料。安格斯牛（n = 138）根据体重（较轻和较重）分为 7 到 10 头/栏。试验采用 2 x 2 析因设计，因子为两个蛋白质水平和两种垫料类型（垫料与不垫料），有四个重复。研究于 6 月至 9 月进行，包括四个为期 28 天的周期。每个畜栏的粪便每隔 28 天刮一次，每个畜栏的混合粪便样本收集。使用 Tedlar 袋从畜栏表面使用 Vac-U-Chamber 与便携式风洞耦合收集空气样本，并在采样后 24 小时内使用温室气体气相色谱仪进行分析。粪便样本分析粗蛋白（CP）、总氮（TN）、氨（NH3）、总挥发性脂肪酸（TVFA）、总碳（TC）、总磷（TP）和钾（K）。空气样本分析甲烷（CH4）、二氧化碳（CO2）和氧化亚氮（N2O）浓度。高蛋白日粮组牛粪便中的总氮浓度显著升高（p < 0.05）。两种处理方式下，乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸等挥发性脂肪酸（VFAs）浓度相似。粪便管理和日粮粗蛋白水平对畜栏表面温室气体排放没有显著影响。
