Methane emissions from beef cattle: effects of fumaric acid, essential oil, and canola oil

The objective of this study was to identify feed additives that reduce enteric methane emissions from cattle. We measured methane emissions, total tract digestibility (using chromic oxide), and ruminal fermentation (4 h after feeding) in growing beef cattle fed a diet supplemented with various additives. The experiment was designed as a replicated 4 x 4 Latin square with 21-d periods and was conducted using 16 Angus heifers (initial BW of 260 +/- 32 kg). Treatments were: control (no additive), fumaric acid (175 g/d) with sodium bicarbonate (75 g/d), essential oil and spice extract (1 g/d), or canola oil (4.6% of DMI). The basal diet consisted of 75% whole-crop barley silage, 19% steam-rolled barley, and 6% supplement (DM basis). Four large chambers (2 animals fed the same diet per chamber) were equipped to measure methane emissions for 3 d each period. Adding canola oil to the diet decreased (P = 0.009) total daily methane emissions by 32% and tended (P = 0.09) to decrease methane emissions as a percentage of gross energy intake by 21%. However, much of the reduction in methane emissions was due to decreased (P < 0.05) feed intake and lower (P < 0.05) total tract digestibility of DM and fiber. Digestibility of all nutrients was also lowered (P < 0.05) by feeding essential oil, but there were no effects on ruminal fermentation or methane emissions. In contrast, adding fumaric acid to the diet increased total VFA concentration (P = 0.03), increased propionate proportions (P = 0.01), and decreased the acetate:propionate ratio (P = 0.002), but there was no measurable effect on methane emissions. The study demonstrates that canola oil can be used to reduce methane losses from cattle, but animal performance may be compromised due to lower feed intake and decreased fiber digestibility. Essential oils had no effect on methane emissions, whereas fumaric acid caused potentially beneficial changes in ruminal fermentation but no measurable reductions in methane emissions.     

Methane emissions from beef cattle: Effects of monensin, sunflower oil, enzymes, yeast, and fumaric acid

Methane emitted from the livestock sector contributes to greenhouse gas (GHG) emissions. Understanding the effects of diet on enteric methane production can help refine GHG emission inventories and identify viable GHG reduction strategies. Our study focused on measuring methane and carbon dioxide emissions, total-tract digestibility, and ruminal fermentation in growing beef cattle fed a diet supplemented with various additives or ingredients. Two experiments, each designed as a 4 x 4 Latin square with 21-d periods, were conducted using 16 Holstein steers (initial BW 311.6 +/- 12.3 kg). In Exp. 1, treatments were control (no additive), monensin (Rumensin, Elanco Animal Health, Indianapolis, IN; 33 mg/kg DM), sunflower oil (400 g/d, approximately 5% of DMI), and proteolytic enzyme (Protex 6-L, Genencor Int., Inc., CA; 1 mL/kg DM). In Exp. 2, treatments were control (no additive), Procreatin-7 yeast (Prince Agri Products, Inc., Quincy, IL; 4 g/d), Levucell SC yeast (Lallemand, Inc., Rexdale, Ontario, Canada; 1 g/d), and fumaric acid (Bartek Ingredients Inc., Stoney Creek, Ontario, Canada; 80 g/d). The basal diet consisted of 75% barley silage, 19% steam-rolled barley grain, and 6% supplement (DM basis). Four large chambers (two animals per chamber) were equipped with lasers and infrared gas analyzers to measure methane and carbon dioxide, respectively, for 3 d each period. Total-tract digestibility was determined using chromic oxide. Approximately 6.5% of the GE consumed was lost in the form of methane emissions from animals fed the control diet. In Exp. 1, sunflower oil decreased methane emissions by 22% (P = 0.001) compared with the control, whereas monensin (P = 0.44) and enzyme had no effect (P = 0.82). However, oil decreased (P = 0.03) the total-tract digestibility of NDF by 20%. When CH(4) emissions were corrected for differences in energy intake, the loss of GE to methane was decreased by 21% (P = 0.002) using oil and by 9% (P = 0.09) using monensin. In Exp. 2, Procreatin-7 yeast (P = 0.72), Levucell SC yeast (P = 0.28), and fumaric acid (P = 0.21) had no effect on methane emissions, although emissions as a percentage of GE intake were 3% (non-significant, P = 0.39) less for steers fed Procreatin-7 yeast compared with the control. This study demonstrates that sunflower oil, ionophores, and possibly some yeast products can be used to decrease the GE lost as methane from cattle, but fiber digestibility is impaired with oil supplementation.     

Animal,feed and rumen fermentation attributes associated with methane emissions from sheep fed brassica crops

Methane emissions from ruminants enhance global warming and lead to a loss of feed energy. The emissions are low when fed brassica crops, but the factors contributing to low emissions are unknown. A meta-analysis was conducted with individual animal data collected from seven experiments. In these experiments, methane emissions were measured using respiration chambers. Animal characteristics, feed chemical composition and rumen fermentation parameters were included for the analysis using multiple regression models. Feed intake level, animal live weight and age were animal factors that were weakly and negatively related to methane yield (g/dry matter intake). The duration in which sheep were fed brassica crops was a significant contributor in the model, suggesting that the effect on emissions diminishes with time. Among a range of feed chemical composition characters, acid detergent fibre and hot-water-soluble carbohydrate contributed significantly to the model, suggesting that both structural and soluble carbohydrates affect methane formation in the rumen. There was no significant correlation between the concentration of sulphate in brassicas and emissions, but nitrate was moderately and negatively correlated with methane yield (r = −.53). Short-chain fatty acid profiles in the rumen of animals fed brassicas were different from those fed pasture, but these parameters only moderately correlated to methane emissions (r = .42). Feeding forage rape resulted in low rumen pH. The pH before morning feeding was strongly correlated to methane yield (r = .90). Rumen pH, together with microbial communities mediated by pH, might lead to low emissions. Bacteria known to produce hydrogen were relatively less abundant in the rumen contents of brassica-fed animals than pasture-fed animals. In conclusion, animal and feed factors, rumen fermentation and microbial communities all affect methane emissions to some extent. The interactions of these factors with each other thus contribute to methane emissions from brassica-fed sheep.     

Effects of mineral salt supplement on enteric methane emissions,ruminal fermentation and methanogen community of lactating cows

We evaluated the effects of mineral salt supplement on enteric methane emissions, ruminal fermentation and methanogen community of dairy cows over a whole lactation period. Ten Holstein cows fed a total mixed ration (TMR) diet were randomly allocated into two groups, one supplied with mineral salts as the treatment group and the other as the control group. The methane measurement showed that the ingestion of mineral salts lowered enteric methane emissions significantly (P < 0.05), with an average of 10.5% reduction over the whole lactation period. Ruminal fermentation analysis showed the mineral salt intake could significantly decrease the acetate : propionate ratio (P < 0.05). Real‐time PCR assay showed that rumen methanogen abundance significantly reduced in the treatment group (P < 0.05) but was not significantly influenced by mineral salt intake over the whole lactation period. Intergroup methanogen community composition was influenced slightly by mineral salt intake; however, significantly different intragroup profiles were apparent throughout the whole lactation period, according to denaturing gradient gel electrophoresis analysis. In conclusion, these results suggested that the effective mitigation of enteric methane emissions by mineral salt intake could be attributed to decreased density of methanogenic archaea and that fluctuations in methane emission over the lactation period might be related to Methanobrevibacter diversity.     

Impact of forage diversity on forage productivity,nutritive value,beef cattle performance,and enteric methane emissions

Greenhouse gas emissions from the beef industry are largely attributed to the grazing sector, specifically from beef cattle enteric methane emissions. Therefore, the study objective was to examine how forage diversity impacts forage productivity, nutritive value, animal performance, and enteric methane emissions. This study occurred over three consecutive grazing seasons (2018 to 2020) and compared two common Midwest grazing mixtures: 1) a simple, 50:50 alfalfa:orchardgrass mixture (SIMP) and 2) a botanically diverse, cool-season species mixture (COMP). Fifty-six steers and heifers were adapted to an Automated Head Chamber System (AHCS) each year (C-Lock Inc., Rapid City, SD) and stratified into treatment groups based on acclimation visitation. Each treatment consisted of four pastures, three 3.2-ha and one 1.6-ha, with eight and four animals each, respectively. Forage production was measured biweekly in pre- and postgrazed paddocks, and forage nutritive value was analyzed using near-infrared reflectance spectroscopy. Shrunk body weights were taken monthly to determine animal performance. Forage availability did not differ between treatments (P = 0.69) but tended lower in 2018 (P = 0.06; 2.40 t dry matter ha⁻¹) than 2019 (2.92 t dry matter ha⁻¹) and 2020 (P = 0.10; 2.81 t dry matter ha⁻¹). Crude protein was significantly lower for COMP in 2018 compared with SIMP. Forage acid detergent fiber content was significantly lower for the COMP mixture (P = 0.02). The COMP treatment resulted higher dry matter digestibility (IVDMD48) in 2018 and 2019 compared with the SIMP treatment (P < 0.01). Animal performance did not differ between treatments (P > 0.50). There was a tendency for the COMP treatment to have lower enteric CH₄ production on a g d⁻¹ basis (P = 0.06), but no difference was observed on an emission intensity basis (g CH₄ kg⁻¹ gain; P = 0.56). These results would indicate that adoption of the complex forage mixture would not result in improved forage productivity, animal performance, or reduced emission intensity compared with the simple forage mixture.     

奶牛常用饲草的体外发酵CH4产量研究

为研究不同饲草对反刍动物甲烷(CH4)排放量的影响,利用虚拟仪器技术设计的体外发酵产气自动记录系统,结合气相色谱仪,测定了奶牛业常用饲草体外发酵72 h后的发酵指标。结果表明:发酵72 h后,供试饲草的CH4产量介于56.85～74.63 mL.g-1DMloss,最高的为玉米(Zea mays L.)秸秆,最低的为苜蓿(Medicagosativa L.)干草Ⅰ。体外发酵程度由高到低依次为青贮玉米、苜蓿干草Ⅰ、苜蓿干草Ⅱ、羊草(Leymus chinensis T.)干草、苜蓿茎秆、玉米秸秆。各饲草的产气动态均呈指数函数变化,趋势相似,在0～24 h内累计产气量迅速增加,24～36 h内增长速率渐缓,36 h以后速率趋于平缓。各饲草的CH4产量与其中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量成显著正相关(P<0.05),与其粗蛋白(CP)含量成极显著负相关(P<0.01);通过逐步回归分析,建立常规养分含量与CH4产量的回归模型:PCH4=60.02-0.91×CP+0.44×ADF(R2=0.96)。综上表明,饲草的CH4产量与其品质有关,优质饲草体外发酵程度高,CH4产量低,从而提高饲料利用率、减少温室效应,而劣质饲草则相反。     

施氮和刈割对辽西北退化草地牧草产量和品质的影响

施氮和刈割是天然草地有效管理方式。为探究退化草地高效利用方式,以辽宁省西北部农牧交错区退化草地为研究对象,设置氮肥添加（0、10 g N·m^-2·a^-1）和刈割处理（留茬高度3、6、12 cm、不刈割）,通过连续两年测定牧草产量和22项牧草品质指标,分析施氮和刈割对辽西北退化草地牧草产量和品质的影响。结果表明：1）施氮显著提高了2018和2019年产草量、粗蛋白和2019年牧草产奶净能、维持净能、增重净能、总可消化养分、奶吨指数,极显著降低了2019年酸性洗涤纤维含量,对退化草地牧草产量、净能以及养分含量的提升均有促进作用。2）刈割显著影响了2018和2019年牧草中性洗涤纤维、钙元素、磷元素含量、体外干物质消化率和相对饲喂价值,2018年粗灰分、镁元素含量以及2019年非纤维性碳水化合物、维持净能、增重净能、总可消化养分和相对饲草品质,在对退化草地进行适度利用的同时牧草品质也有较大提升。3）施氮和刈割交互作用对退化草地牧草粗蛋白、粗灰分、产奶净能以及奶吨指数有显著影响。4）牧草粗灰分、酸性洗涤纤维、中性洗涤纤维、可消化中性洗涤纤维、中性洗涤纤维消化率、镁元素、产奶净能、维持净能、增重净能、奶吨指数、总可消化养分以及相对饲喂价值共12项营养品质指标与粗蛋白之间存在显著相关关系。研究表明,施氮和刈割作为退化草地的有效管理和利用方式,单独作用或交互作用均对牧草产量和品质的提升有不同程度的正向反馈,其中以施氮结合留茬3 cm刈割处理下牧草产量和品质最高,可为退化草地的合理利用和可持续发展提供理论参考。     

粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响

本试验旨在研究粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响。试验采用单因素随机区组设计,将 １６头体重、年龄、胎次相近的,处于干奶期的健康荷斯坦奶牛分为 ４组,每组 ４头。以常用的粗饲料设计 Ａ（玉米青贮 ＋玉米秸秆）、Ｂ（玉米青贮 ＋羊草）、Ｃ（玉米青贮 ＋玉米秸秆 ＋羊草）、Ｄ（玉米青贮 ＋苜蓿草 ＋羊草）４种粗饲料组合的饲粮。结果表明：饲粮Ｄ干物质、有机物和中性洗涤纤维的消化率最高,显著高于其他各饲粮（Ｐ＜０．０５）,其次为饲粮Ｂ和饲粮 Ｃ,饲粮 Ａ最低,显著低于其他各饲粮（Ｐ＜０．０５）,各饲粮的酸性洗涤纤维消化率差异不显著（Ｐ＞０．０５）。粗饲料组合显著影响饲粮摄入总能、能量消化率和能量代谢率（Ｐ＜０．０５）,饲粮 Ｄ甲烷能占摄入总能比显著低于其他 ３种饲粮（Ｐ＜０．０５）。各饲粮的粪氮、尿氮占摄入总氮比差异不显著（Ｐ＞０．０５）,饲粮 Ｄ的氮消化率显著高于饲粮 Ｂ与饲粮 Ｃ（Ｐ＜０．０５）,且饲粮 Ｂ显著高于饲粮 Ａ（Ｐ＜０．０５）;饲粮 Ｂ、饲粮 Ｄ的氮利用率显著高于饲粮 Ａ（Ｐ＜０．０５）。由此可见,玉米青贮 ＋苜蓿草 ＋羊草型饲粮的养分消化率、能量和氮的利用均优于其他各饲粮,羊草与玉米秸秆之间存在正组合效应,两者搭配使用可提高玉米秸秆的消化率,优化能量和氮的利用。     

Use of condensed tannin extract from quebracho trees to reduce methane emissions from cattle

Our objective was to determine if condensed tannin extract from quebracho trees (Schinopsis quebracho-colorado; red quebracho) could be used to reduce enteric methane emissions from cattle. The experiment was designed as a repeated 3 x 3 Latin square (4 squares) with 3 treatments (0, 1, and 2% of dietary DM as quebracho tannin extract) and 3 28-d periods. Six spayed Angus heifers (238 +/- 13.3 kg of initial BW) and 6 Angus steers (207 +/- 8.2 kg of initial BW) were each assigned to 2 squares. The measured condensed tannin content of the extract was 91%, and the basal diet contained 70% forage (DM basis). Feeding quebracho tannin extract had no effect on BW, ADG, or nutrient intakes. Furthermore, it had no effect on DM, energy, or fiber (ADF and NDF) digestibility, but apparent digestibility of CP decreased linearly (P < 0.001) by 5 and 15% with 1 and 2% quebracho tannin extract, respectively. There were no effects of quebracho tannin extract on methane emissions (g/d, g/kg of DM, % of GE intake, or % of DE intake). Feeding up to 2% of the dietary DM as quebracho tannin extract failed to reduce enteric methane emissions from growing cattle, although the protein-binding effect of the quebracho tannin extract was evident.     

饲粮NDF/NFC对泌乳后期奶牛瘤胃甲烷排放量、营养物质表观消化率及生产性能的影响

为研究不同中性洗涤纤维/非纤维性碳水化合物(NDF/NFC)饲粮对泌乳后期奶牛甲烷排放量、营养物质消化率和生产性能的影响,试验选用体重(777.46±27.31)kg、胎次(1.5±0.15)胎、泌乳天数(242.92±15.28)d、产奶量(18.75±0.62)kg/d的奶牛12头,随机分配到3组,每组4头。各组饲粮NDF/NFC分别为2.10(精粗比为42:58)、1.96(精粗比为37:63)、1.52(精粗比为30:70),采用六氟化硫(SF_6)示踪技术测定自然状态下泌乳奶牛甲烷排放量。预试期14 d,正试期9 d。结果表明:饲喂不同NDF/NFC饲粮的泌乳后期奶牛甲烷排放量、甲烷能、单位干物质采食量的甲烷排放量以及单位总能摄入量的甲烷能均有显著差异;随着NDF/NFC降低,奶牛生产性能、饲料转化率和营养物质消化率无显著差异。综上,在不影响奶牛健康和生产性能的前提下,NDF/NFC为1.52的低NDF组饲料能显著降低泌乳后期奶牛瘤胃甲烷排放量。     

Effect of divergence in residual methane emissions on feed intake and efficiency,growth and carcass performance,and indices of rumen fermentation and methane emissions in finishing beef cattle

Residual expressions of enteric emissions favor a more equitable identification of an animal’s methanogenic potential compared with traditional measures of enteric emissions. The objective of this study was to investigate the effect of divergently ranking beef cattle for residual methane emissions (RME) on animal productivity, enteric emissions, and rumen fermentation. Dry matter intake (DMI), growth, feed efficiency, carcass output, and enteric emissions (GreenFeed emissions monitoring system) were recorded on 294 crossbred beef cattle (steers = 135 and heifers = 159; mean age 441 d (SD = 49); initial body weight (BW) of 476 kg (SD = 67)) at the Irish national beef cattle performance test center. Animals were offered a total mixed ration (77% concentrate and 23% forage; 12.6 MJ ME/kg of DM and 12% CP) ad libitum with emissions estimated for 21 d over a mean feed intake measurement period of 91 d. Animals had a mean daily methane emissions (DME) of 229.18 g/d (SD = 45.96), methane yield (MY) of 22.07 g/kg of DMI (SD = 4.06), methane intensity (MI) 0.70 g/kg of carcass weight (SD = 0.15), and RME 0.00 g/d (SD = 0.34). RME was computed as the residuals from a multiple regression model regressing DME on DMI and BW (R² = 0.45). Animals were ranked into three groups namely high RME (>0.5 SD above the mean), medium RME (±0.5 SD above/below the mean), and low RME (>0.5 SD below the mean). Low RME animals produced 17.6% and 30.4% less (P < 0.05) DME compared with medium and high RME animals, respectively. A ~30% reduction in MY and MI was detected in low versus high RME animals. Positive correlations were apparent among all methane traits with RME most highly associated with (r = 0.86) DME. MY and MI were correlated (P < 0.05) with DMI, growth, feed efficiency, and carcass output. High RME had lower (P < 0.05) ruminal propionate compared with low RME animals and increased (P < 0.05) butyrate compared with medium and low RME animals. Propionate was negatively associated (P < 0.05) with all methane traits. Greater acetate:propionate ratio was associated with higher RME (r = 0.18; P < 0.05). Under the ad libitum feeding regime deployed here, RME was the best predictor of DME and only methane trait independent of animal productivity. Ranking animals on RME presents the opportunity to exploit interanimal variation in enteric emissions as well as providing a more equitable index of the methanogenic potential of an animal on which to investigate the underlying biological regulatory mechanisms.     

The effect of replacing nonstructural carbohydrates with soybean oil on the digestibility of fibre in trotting horses

The hypothesis tested was that the intake of extra fat at the expense of an isoenergetic amount of nonstructural carbohydrates reduces fibre utilisation in horses. In a crossover trial with feeding periods of 42 days each, 6 mature trotting horses (age 4-12 years, bodyweight 340-476 kg) were given either a control or test diet. The test concentrate was formulated to contain 37% of net energy in the form of soybean oil. The control concentrate contained an isoenergetic amount of corn starch plus glucose. The concentrates were fed in combination with the same amount of hay so that the control and test diet contained 25.13 and 86.66 g crude fat/kg dry matter, respectively. Apart from the amounts of fat and nonstructural carbohydrates, the 2 diets were identical. The test diet reduced the apparent total tract digestibilities of crude fibre, neutral and acid detergent fibre by 8.0 (P = 0.007), 6.2 (P = 0.022) and 8.3 (P = 0.0005) percentage units, respectively. It is suggested that a high fat intake by horses may increase the amount of fat entering the large intestine to levels that depress fermentation by cellulolytic bacteria. The observed interaction between fat content of the diet and fibre utilisation may have consequences for practical horse feeding in that calculating the energy content of test diets on the basis of feedstuff tables leads to overestimating the amount of energy provided by the high-fibre ingredients of the diets.     

日粮不同NDF/NFC水平对周岁后荷斯坦奶牛生产性能、营养物质消化率、瘤胃发酵特征和甲烷排放的影响

本试验研究了日粮中不同中性洗涤纤维/非纤维性碳水化合物（NDF/NFC）水平对周岁后荷斯坦奶牛生产性能、营养物质消化率、瘤胃发酵特征及甲烷产量的影响，并在此基础上建立了甲烷排放预测模型，旨在获得我国生产模型下的甲烷排放规律和甲烷转化因子，为提高奶牛能量利用效率、建立国家或区域性温室气体排放清单和探索减排策略提供科学依据和支撑。将45头体况良好，平均为15月龄的荷斯坦后备奶牛随机分为3组，每组15头牛：低日粮NDF/NFC组（NDF/NFC=0.60）、中日粮NDF/NFC组（NDF/NFC=0.75）和高日粮NDF/NFC组（NDF/NFC=0.90），试验期为70 d，包括14 d的预饲期和56 d的正试期。结果表明：1）提高日粮NDF/NFC水平显著降低了奶牛的干物质采食量、有机物采食量、平均日增重、干物质和粗蛋白的表观消化率（P<0.05）；2）提高日粮NDF/NFC水平显著增加了瘤胃内总挥发性脂肪酸产量、乙酸的相对含量和乙酸/丙酸比例（P<0.05），显著降低了丙酸的相对含量（P<0.05）；3）随着日粮NDF/NFC水平的提高，瘤胃甲烷和甲烷能产量、甲烷/代谢体重、甲烷/干物质采食量、甲烷/有机物采食量、甲烷/中性洗涤纤维采食量显著提高（P<0.05）。甲烷转化因子也随着日粮NDF/NFC水平的增加而显著提高（P<0.05）；4）基于体重、采食量、营养物质含量和NDF/NFC分别建立了甲烷预测模型，其中基于干物质采食量和中性洗涤纤维采食量建立的预测模型的决定系数最高（R²=0.77）。因此，提高日粮中NDF/NFC水平可显著降低周岁后荷斯坦奶牛的生产性能、营养物质消化率和瘤胃内丙酸的相对含量，可显著提高瘤胃甲烷产量和甲烷转化因子。     

不同中性洗涤纤维与非纤维性碳水化合物比值饲粮对肉用绵羊甲烷排放的影响

本试验旨在研究不同中性洗涤纤维(NDF)与非纤维性碳水化合物(NFC)比值(NDF/NFC)饲粮对肉用绵羊甲烷排放的影响。试验采用4×4完全拉丁方试验设计,将16只杜泊×小尾寒羊杂交羯羊随机分成4组,每组4只,按维持水平饲喂NDF/NFC分别为3.02(饲粮1)、2.32(饲粮2)、1.58(饲粮3)、1.04(饲粮4)的全混合颗粒饲粮(玉米秸秆为粗饲料来源)。试验共进行4期,每期18 d,包括3 d的调整期、7 d的预试期和8 d的正试期,在正试期内测定甲烷产量、饲粮总能和营养物质表观消化率。结果表明:饲粮2的甲烷日排放量显著高于饲粮3和4(43.43 L/d vs.38.88和35.98 L/d;P0.05)。与饲粮1相比,饲粮2和3的每千克干物质采食量(DMI)甲烷排放量显著增加(38.00 L/kg DMI vs.42.24、41.69 L/kg DMI;P0.05),但是饲粮2、3和4之间差异不显著(P0.05)。随着NDF/NFC的降低,每千克可消化有机物(DOM)的甲烷排放量逐渐降低,饲粮4的每千克DOM的甲烷排放量显著低于饲粮1、2和3(58.78 L/kg DOM vs.75.00、73.35和64.11 L/kg DOM;P0.05)。随着NDF/NFC的降低,每千克中性洗涤纤维采食量(NDFI)或酸性洗涤纤维采食量(ADFI)的甲烷排放量逐渐增加,且各饲粮之间差异显著(P0.05)。综上所述,结合各营养物质表观消化率和甲烷排放效率,在维持水平下,采用NDF/NFC为1.04的玉米秸秆饲粮作为肉用绵羊甲烷减排的饲粮最合适。     

全株大豆和玉米秸秆混合青贮试验

为研究不同比例的全株大豆和玉米秸秆混合青贮对营养成分、发酵品质、能量值的影响,试验分为5个处理组,全株大豆与玉米秸秆的比例分别为1:0、2:1、1:1、1:2、0:1,每组3个重复。结果表明:与玉米秸秆相比,全株大豆与玉米秸秆1:1混合青贮的粗蛋白质、粗脂肪、赖氨酸、钙的含量以及干物质体外消化率分别提高了55.89%、192.10%、107.69%、250.00%、6.52%(P<0.05),粗灰分、中性洗涤纤维、酸性洗涤纤维、木质素、可溶性碳水化合物的含量显著降低(P<0.05),产奶净能、维持净能显著提高(P<0.05);与全株大豆相比,全株大豆与玉米秸秆1:1混合青贮的乳酸含量提高了34.65%(P<0.05),乙酸和丁酸含量及pH显著降低(P<0.05)。综上,建议全株大豆与玉米秸秆以1:1比例混合青贮。     

稻秸、象草和杂交狼尾草青贮的研究

为探讨乳酸菌(Lactobacillus plantarum)添加剂对不同原料青贮发酵品质的影响,对水稻(Oryzasativa L.)的2个中粳稻品系(9015,9019)稻秸和2个热带牧草(象草(Pennisetum purpureum),杂交狼尾草(Pennisetum americanum×P.purpureum))进行了青贮研究。将新鲜稻秸或牧草切碎后添加乳酸菌(0.02 g·kg^-1),同时设对照组(无添加物),袋装青贮45 d后取样检测。结果表明:添加乳酸菌的青贮饲料其可溶性碳水化合物(WSC)含量、有机物消化率(IVOMD)、干物质回收率(DMR)、乳酸(LA)含量、乳酸/乙酸(LA/AA)比对照提高;中性洗涤纤维(NDF)含量、酸性洗涤纤维(ADF)含量、pH、氨态氮/总氮(AN/TN)、挥发性脂肪酸(VFAs)含量下降;乳酸菌(LAB)对WSC含量、NDF含量、DMR、IVOMD、LA含量、AN/TN、乙酸(AA)含量、丙酸(PA)含量、LA/AA、VFAs含量影响差异极显著(P<0.01)。不同的青贮原料对青贮饲料的营养特性指标、pH、LA含量、AN/TN、LA/AA、AA含量和VFAs含量影响极显著(P<0.01),杂交狼尾草的青贮品质最佳。添加乳酸菌可以改善青贮饲料的品质,但不同原料间的青贮品质差异较大。     

Net energy value of ammoniated wheat straw

Eight steers (327 kg average) were fed diets containing either nontreated or anhydrous NH3-treated wheat straw in a two-period crossover design. Intake and digestibilities of dry matter, gross energy, neutral detergent fiber, acid detergent fiber and crude protein were measured by total collection. Energy losses in urine and methane were determined. Heat production was determined by indirect respiration calorimetry on steers fed both diets and after they were fasted. Ammoniation of the straw raised its N content from .49 to 1.59% (P less than .001). Dry matter (DM) intake was increased (P less than .01) by the process from 1.0 to 1.3% of body weight. Digestibility coefficients of dry matter and energy, as well as those for fiber, were increased (P less than .001) by four percentage units or more. Crude protein digestibility, however, was depressed (P less than .001) from 67.8% to 53.5% by ammoniation. Urinary energy as a percentage of gross energy intake (GEI) was reduced (P less than .05) by NH3 treatment from 4.10 to 3.74%. Methane energy was not different (P greater than .10). Metabolizable energy was improved (P less than .001) by ammoniation, increasing from 45.2 to 50.0% of GEI. Daily heat production was higher (P less than .01) for steers consuming the ammoniated straw diet, increasing from 113.7 to 125.3 kcal/wt.75), and was due to higher metabolizable energy intake (MEI) since partial efficiency of MEI used for maintenance did not differ (P greater than .10) between diets. The higher net energy value of the ammoniated wheat straw diet (1.45 vs 1.26 kcal/g DM) was due mainly to decreased fecal loss and a slight decline in urinary loss.     

种植密度对玉米产量及青贮品质的影响

以科多8号青贮专用型玉米（Zea mays）为试验材料,设低(6.80万株/hm2)、中(8.00万株/hm2)、高(9.55万株/hm2)3个种植密度处理,分析种植密度对玉米产量、发酵品质、营养成分、硝酸盐和亚硝酸盐含量的影响。结果表明,低种植密度植株高度、单株叶质量、茎质量均最高,但鲜草产量和粗蛋白产量却低于其他处理;青贮饲料营养成分随密度变化不一致,酸性洗涤纤维含量、中性洗涤纤维含量和粗脂肪含量均随密度的增加而提高,粗蛋白和可溶性碳水化合物随密度的增加而降低;青贮降低了原料的硝酸盐和亚硝酸盐含量,种植密度对硝酸盐和亚硝酸盐含量影响不显著。比较产量、发酵品质、营养成分、硝酸盐类物质含量,中种植密度玉米产量和青贮质量较高,为适宜种植密度。     

Effect of a non‐forage fiber of red bean hulls on ruminal mat characteristics,chewing activity and milk production in dairy cows

The evaluation of red bean hulls (RBH) as a non‐forage fiber source on ruminal mat formation, chewing activity and milk production was determined using two experiments. In experiment 1, four non‐lactating, rumen‐cannulated Holstein cows were offered a control diet of 60.1% forage, and an RBH diet of 51.6% forage and 9.4% RBH. Although the neutral detergent fiber (NDF) intake was higher with the RBH diet than the control diet, the physically effective NDF (peNDF) intake was lower. The rumination period tended to be longer with the RBH diet than with the control diet and the ruminal mat was formed even when the RBH diet was consumed. Ruminal fermentation parameters were not affected by treatment. In experiment 2, 40 lactating cows were fed a control diet of 53.4% forage or an RBH diet of 50.3% forage and 8.1% RBH. Dry matter intake, chewing activity and milk production were not affected by diet. Cows sorted against NDF in the control diet, but not in the RBH diet. It is concluded that normal ruminal function can be maintained because the ruminal mat was stratified and rumination activity was not reduced even when a low peNDF diet that contained RBH was given to dairy cows.