Effects of supplementary corn silage on the feed intake and milk production of time-restricted grazing dairy cows

The effects of supplementary corn silage (CS) of either 2 or 4 kg of dry matter (DM; S + 2 and S + 4, respectively) above the energy requirement for milk production and maintenance for grazing dairy cows (S) were determined. Time‐restricted grazing was used to compare the feed intake, milk production, and nitrogen and energy use of lactating cows. The experiment was carried out on two different pastures using a 3 × 3 Latin square design for each pasture. Cows were grazed for 5 h on a rotational grazing system and were fed concentrate (1 kg per 5 kg of milk yield). Herbage intake was measured using a weighing technique. To calculate the energy and nitrogen use, whole feces and urine were collected. There was no statistical effect of the pastures. Herbage intake decreased by the addition of CS (P = 0.02). The reduction of herbage DM intake per unit consumption of supplementary CS towards the S group were 0.80 and 0.45 kg for the S + 2 and S + 4 groups, respectively. The total DM intake for the S + 4 group was higher than that for the S and S + 2 groups (P = 0.02). Milk yield did not differ among treatments, even though the total DM intake for the S + 4 group was higher than that of the S and S + 2 groups. Nitrogen and energy use did not differ with the addition of CS.     

Weed suppression in mixed cropped grain peas and false flax (Camelina sativa)

Mixed cropping peas with false flax, a brassica oil seed crop, in additive arrangements had a significant suppressive effect on weed coverage (63% in 2003 and 52% in 2004), compared with the monocropped pea plots. Weed suppression by false flax was apparently restricted to the establishment phase, because effects were significant against the key annuals Fallopia convolvulus, Sonchus oleraceus and Matricaria recutita, but ineffective towards the major perennials Cirsium arvense and Elytrigia repens. Relatively higher yields in mixed stands with calculated land equivalent ratios (LER) of 1.43 (2003) and 1.98 (2004) were the result of low monocrop yields mainly related to weed pressure not only in pea but also in false flax. Partial LERs were in favour of peas, demonstrating a balanced but asymmetric complementarity of the components, with peas as the main and false flax as the minor crop component. The role of false flax in row‐cropped peas can be characterized as both a smother crop and weed antagonist with no obvious indications for allelopathic traits. Weed suppression was probably achieved by a mutually enhanced competitiveness of both crop components, indicating a mechanism based on resource allocation, but further research is needed for a better understanding of weed‐suppressive traits in pea–false flax mixed cropping systems.     

球孢白僵菌混合制剂的加工研究

球孢白僵菌混合粉剂是由５１％的孢子粉、２０％紫外保护剂、２５％载体和４％的灭幼脲Ⅲ号,经正交设计优化配方得到。室内生物测定结果表明,此剂对３～４龄马尾松毛虫幼虫ＬＴ５０为５．７ｄ。林间放菌防效达７４．２７％。室温下贮藏０．５ａ,孢子萌发率比高孢粉剂提高１０倍以上。     

Transmission by aphids of potato spindle tuber viroid encapsidated by potato leafroll luteovirus particles

Potato spindle tuber viroid (PSTVd) was transmitted by Myzus persicae to Physalis floridana from P. floridana plants that also were infected with potato leafroll luteovirus (PLRV), whereas it was not transmitted by aphids from plants infected with PSTVd alone. Dot-blot hybridisation was used to detect PSTVd. The results indicate that PLRV can assist PSTVd in its transmission by M. persicae. Doubly infected, aphid-inoculated P. floridana plants from the previous experiment were used as the source plants in aphid transmission tests to the tomato cv. Rutgers, P. floridana and Datura stramonium. PSTVd was detected in 17 of 30 plants of tomato. The viroid was not detected by dot-blotting in any plant of P. floridana and D. stramonium in this experiment, but it was recovered from some plants by sap inoculation of the Rutgers plants. Treatment with RNase A of PLRV preparations purified from doubly infected plants indicated that PSTVd was encapsidated by PLRV particles.     

樟子松人工林鼠害防治的探讨

根据樟子松人工鼠害发生特点和以往防治实践,提出了“以营林为基本措施”,生物,化学防治,人工和机械防除为辅助措施,综合防治樟子松鼠害”的方针,并着重阐述了营林防治措施及营造防鼠混交林的可行性和方法。     

大麦黄矮病毒GPV与GAV株系间异源装配现象的初步研究

 以我国麦区的大麦黄矮病毒GPV、GAV株系为材料,利用它们的蚜传特异性,将由禾谷缢管蚜传播的GPV和由麦长管蚜传播的GAV混合侵染到岸黑燕麦上,并进行继代传毒。混合侵染后代蚜传表现型的变化初步表明存在异源装配现象,且表现型混合发生的比例较高。用DAS-ELISA和RT-PCR法对混合侵染后代进行了测定,进一步证明了异源包装现象的存在。部分基因的核苷酸序列分析初步显示所测定的混合侵染后代中没有发生基因重组。     

应用土壤无机氮测试优化青贮玉米氮素管理(简报)

在北京郊区通过田间试验研究了应用土壤无机氮测试优化青贮玉米氮素管理。结果表明,1)施用氮肥显著促进青贮玉米的生长和氮素的吸收。2个施氮处理与对照相比,籽粒产量增加41%~46%,植株含氮量增加11%~13%;2)基于土壤无机氮测定的氮肥分期优化管理在玉米全生育期施氮165 kg/hm2,与习惯管理(施氮360kg/hm2)相比,节氮54%,但二者产量差异不显著;3)分期优化管理减低了对环境的污染,其氮素损失为83kg/hm2,较传统施氮降低40 kg/hm2,同时,分期优化管理提高氮肥利用率16%。     

不同生物制剂处理去穗玉米秸青贮对奶牛营养价值的影响

为研究生物制剂对玉米秸青贮营养成分含量变化和瘤胃内降解率的影响。本试验用纤维素酶1g/kg和乳酸菌0.025%分别添加制作玉米秸青贮;用3头装有永久性瘘管荷斯坦乳牛,按3×3拉丁方设计,对不同处理的玉米秸青贮进行了瘤胃内降解率测定。结果为:①未处理、酶制剂处理与菌制剂处理的去穗玉米秸青贮的NDF和ADF含量之间比较差异显著(P<0.05),即未处理>菌处理>酶处理。酶处理和菌处理的去穗玉米秸青贮的CP含量分别比未处理组高1.54和1.57个百分点(P<0.05)。②各种处理去穗玉米秸青贮DM和NDF有效降解率之间存在显著差异(P<0.05),即酶制剂处理>菌制剂处理>未处理;生物制剂处理的去穗玉米秸青贮ADF和CP的有效降解率显著高于未处理组,但酶制剂和菌处理之间差异不显著。表明酶和菌制剂处理均能提高去穗玉米秸青贮品质及其主要营养成分降解率,但在DM和NDF有效降解率指标上,酶制剂处理去穗玉米秸青贮效果优于菌制剂处理。     

糖蜜等复合添加物对苜蓿青贮品质的影响

本试验研究了添加糖蜜对用麸皮、稻草、米糠调节水分的苜蓿青贮品质的影响。试验采用拉丁方设计,在刚收获切碎的苜蓿原料中,分别加入0%、5%、10%的糖蜜调节糖分,同时加入麸皮、稻草、米糠调节含水量。结果表明：添加糖蜜后明显改善了青贮饲料的品质,青贮饲料的颜色发黄,气味酸香,质地松软,青贮料的可溶性糖分和pH值均快速下降,与不加糖蜜的各处理差异显著（P〈0.05）,氨态氮（NH3-N）含量及氨态氮与总氮的比值（NH3-N/TN）也均以10%糖蜜添加量最低,除稻草组外、与不加糖蜜的各处理差异显著（P〈0.05）;随着糖蜜用量的增加,重量损失却呈上升趋势。同时麸皮组和米糠组的失重相对较大,稻草组失重较少。     

不同比例青贮玉米秸秆日粮的鹅消化率

为了探索鹅对青贮玉米秸秆利用的可行性与效果,本试验选取24月龄的健康五龙鹅30只,随机分为5组,每组6个重复。各试验组日粮青贮玉米秸秆的比例分别为24.30%、34.60%、42.60%、49.10%、53.60%,采用全收粪法进行代谢试验,检测饲料与粪便中的各种营养成分,确定其消化率,并观察肠道微生物菌群变化。试验结果表明:在代谢能(ME)和粗蛋白质(CP)摄入量基本一致的条件下,随着青贮玉米秸秆添加水平的提高,粗纤维(CF)的消化率为18.16%~48.28%,中性洗涤纤维(NDF)42.68%~58.51%,酸性洗涤纤维(ADF)28.56%~49.32%;氮沉积量、净蛋白质利用率(NPU)各组间差异显著(P<0.05);各组粪中的氨态氮(NH3-N)浓度呈下降趋势;除甘氨酸表观消化率偏低但组间差异极显著(P<0.01)外,其他各种氨基酸表观消化率(AAAD)均较高(77.30%~93.10%)。Ca表观消化率随青贮玉米秸秆添加比例递增呈显著递减趋势(P<0.05);P表观消化率在添加53.60%青贮玉米秸秆时显著低于其他各组(P<0.05)。碱性磷酸酶(AKP)活性与CF、NDF和ADF的消化率呈显著负相关(P<0.05),与Ca的表观消化率呈极显著正相关(P<0.01);谷草转氨酶(GOT)、谷丙转氨酶(GPT)酶活与CF呈显著负相关(P<0.05),与Ca的表观消化率呈显著正相关(P<0.05)。青贮秸秆添加量在24.30%~49.10%时,粪便中双歧杆菌、乳酸杆菌数量均随秸杆添加水平的升高而增多(P<0.05);大肠杆菌数量总体呈下降趋势。试验说明鹅能较好的利用青贮玉米秸秆中的营养物质,利用青贮玉米秸秆养鹅是可行的。