Effect of dietary polymer-coated urea and sodium bentonite on digestibility,rumen fermentation,and microbial protein yield in sheep fed high levels of corn stalk

Four ruminally cannulated thin-tailed Han×Dorper crossbreed wethers were used in a 4×4 Latin square design experiment to evaluate the effect of polymer-coated urea (PCU) (Optigen II, Alltech Inc., Nicholasville, KY) and sodium bentonite (SB) on intake, nutrient digestibility, nitrogen retention, rumen fermentation and microbial nitrogen in sheep fed high levels of corn stalk. Four isonitrogenous and isocaloric dietary treatments composed of 60% corn stalk and 40% concentrate (DM basis) were offered twice daily in two equal portions at 7:00 and 19:00 h ad libitum to ensure about 5% ort. The treatments were control (CON), PCU (soybean meal replaced by 1.8% Optigen), SB (CON diet with an additional 2% SB), and PCUSB (PCU diet with an additional 2% SB). Sheep on PCU treatment showed a greater OM digestibility (P<0.05), and nitrogen digestibility (P<0.01) compared to other treatments, but digestibility of other nutrients and dry matter intake (DMI) did not change. SB did not alter nutrient digestibility except for nitrogen. Different treatments did not affect nitrogen intake, or its urinary excretion. Nitrogen retention tended to be higher (P=0.09) in sheep fed Optigen. Moreover, purine derivatives (PD) and microbial nitrogen were not influenced by different treatments. The pH and total VFA were also not influenced by the treatments. Propionate proportions increased (P<0.01) in diets that included Optigen, but an addition of SB to Optigen did not alter the ratios. NH₃–N levels in PCU continuously increased, with the highest level achieved 3 h after feeding, which were sustained for up to 7 h. No differences were discerned in ruminal kinetics of corn stalk DM for different treatments. The PCU improved the effective degradability (ED) of corn stalk DM in 0.02 or 0.04 flow rates out of the rumen compared to both CON and PCUSB (P<0.05), but SB improved ED in 0.06 flow rates out of the rumen compared to CON. Thus, using Optigen as a new source of non-protein nitrogen to replace soybean meal in sheep fed high levels of corn stalk improved the digestibility of OM, nitrogen, and ED. Addition of SB to Optigen had no beneficial effects on nutrient digestibility, nitrogen retention, microbial nitrogen, or rumen fermentation and ED.     

山西省典型土壤对重金属Cu、Zn和Pb等温吸附特征及应用

寻求高效廉价重金属吸附材料在污水重金属去除领域具有重要意义.本研究采用摇瓶试验,研究了山西省石灰性黏壤土、石灰性砂壤土及碱性膨润土对Cu、Zn和Pb的等温吸附效果,并利用土柱吸附试验进一步研究了3类吸附材料对污水处理厂入厂污水中重金属的实际吸附去除能力.研究结果表明,石灰性黏壤土、石灰性砂壤土及碱性膨润土对污水中Cu、Zn和Pb的等温吸附行为均可用Freundlich吸附等温线显著拟合.吸附材料对Cu、Zn和Pb的吸附作用力与吸附容量呈现石灰性黏壤土＞碱性膨润土＞石灰性砂壤土的变化趋势.石灰性黏壤土、石灰性砂壤土及碱性膨润土对3类重金属的吸附作用力表现为Zn＞Cu＞Pb、Cu＞Zn＞Pb与Cu＞Zn＞Pb,而吸附容量顺序却为Cu＞Zn＞Pb、Pb＞ Cu ＞Zn及Cu＞Pb＞Zn.石灰性黏壤土对污水处理厂接纳污水中Cu、Zn和Pb的吸附去除率为79.9％、97.7％和73.4％,碱性膨润土对相应污水重金属指标的去除率也高达70.3％、90.6％和90.6％.该研究结果可为湿地污水处理土壤的选择以及污水重金属吸附材料的选择提供一定的理论依据.     

天然钠基膨润土菌渣复合材料对提高沙土保水保肥效应的影响

中国西北地区沙漠边缘地带存在干旱缺水、土壤沙化程度高、漏水漏肥严重等问题，严重影响了植物正常生长，制约了农业和林果业可持续发展。该研究探究天然钠基膨润土菌渣复合材料对沙土保水保肥性能的影响。通过室内模拟试验，采用茶袋法及土柱模拟法，研究不同用量膨润土P（0、3.0%、5.0%、7.0%、9.0%），不同膨润土菌渣复合材料JF（膨润土+菌渣+腐植酸）、JA（膨润土+菌渣+氨基酸）、JN（膨润土+菌渣+牛粪）及不同主材比例（膨润土与菌渣比分别为1/2、1/2.5、1/3、1/3.5）对改善沙土漏水漏肥的效果。结果表明：JF、JA及JN组处理较P组处理可更大程度地提高沙土吸水倍数及持水性能；土柱淋溶条件下，P组处理可明显降低沙土水分累积渗漏量达18.00%～26.17%，氮素累积渗漏量达11.58%～27.22%，钾素累积渗漏量达2.82%～7.78%；JF1、JA1及JN1处理可明显降低沙土水分累积渗漏量达25.53%～30.31%，氮素累积渗漏量达25.66%～32.36%，钾素累积渗漏量达6.35%～10.73%），其中JF1处理降幅最大，且当膨润土用量为菌渣用量的一半，辅材为腐植酸时效果最佳，这也反映出菌渣及腐植酸的添加对膨润土提高沙土保水保肥性能具有明显的促进作用。试验表明在沙土中添加钠基膨润土菌渣复合材料可提高沙土保水保肥性能，特别是在减少氮素淋溶损失方面具有良好效果，研究结果能够为西北风沙区生态修复及乡村振兴提供策略和依据。     

秸秆改良剂对沙质土有机质和阳离子交换量的影响

通过盆栽实验,探究秸秆、膨润土和PAM的共同作用对砂质土壤有机质和阳离子交换量的影响,寻找改良剂的最佳配方,为秸秆沙质土壤改良剂与产业化示范提供数据基础。结果表明,秸秆、膨润土和PAM共同作用显著提高了沙质土的有机质的含量、腐殖化系数以及阳离子交换量。当秸秆预产物、膨润土和PAM的比例按900：100：30,施加量为10g/kg时,处理60天后达到了最好的效果,使沙质土有机质、腐殖质含量以及阳离子交换量分别较对照提高了28%、25%、36%。     

BS-12+DTAB复配修饰膨润土吸附Cr(Ⅵ)和Cd2+的研究

为了探究和比较两性+阳离子复配修饰膨润土对不同类型重金属离子[Cr(Ⅵ)和Cd~(2+)]的吸附效应及影响机制,采用阳离子型表面修饰剂十二烷基三甲基溴化铵(DTAB或DT)复配修饰两性表面修饰剂十二烷基二甲基甜菜碱(BS-12或BS)修饰膨润土,批处理法研究各复配修饰土样对Cr(Ⅵ)和Cd~(2+)的等温吸附的异同,并对比温度、pH值和离子强度对吸附的影响。结果表明:各复配修饰膨润土对Cr(Ⅵ)和Cd~(2+)的吸附等温线均符合Langmuir模型。供试土样对Cr(Ⅵ)的平衡吸附量呈现BS+150DT(150%CEC的DTAB复配修饰膨润土)BS+100DTBS+50DTBS+25DTBSCK(膨润土)的趋势,且最大吸附量(qm)为205.67 mmol·kg-1(BS+150DT)。土样对Cd~(2+)的平衡吸附量表现为BSCKBS+25DTBS+50DTBS+100DTBS+150DT,其qm值为232.38 mmol·kg-1(100BS)。10~40℃范围内,CK、BS修饰土对Cr(Ⅵ)吸附量为增温正效应,而BS+DT复配修饰土对Cr(Ⅵ)吸附呈现自发、焓减和熵增的特征;各供试土样对Cd~(2+)的吸附均表现为自发、焓增和熵增的特征。随着pH值的升高,各修饰土样对Cr(Ⅵ)的吸附量均逐渐降低,而对Cd~(2+)的吸附量逐渐增加。离子强度增加不利于供试土样对Cr(Ⅵ)和Cd~(2+)的吸附。BS+DT复配修饰膨润土表面的电荷类型、电荷数量是决定Cr(Ⅵ)和Cd~(2+)吸附差异的主要因素。     

BS/DTAB复配修饰膨润土的表征及对苯酚、菲的不同吸附模式

为了探究总修饰比例对复配修饰膨润土表面结构特性及对不同疏水性的有机污染物(苯酚、菲)吸附模式的影响。采用十二烷基三甲基溴化铵(DTAB)复配十二烷基二甲基甜菜碱(BS-12)修饰膨润土,研究了复配修饰膨润土总碳和总氮含量、比表面(SBET)、X射线衍射(XRD)、红外光谱(FTIR)和扫描电镜(SEM)的特征,并分析了总修饰比例、表面特性及吸附量三者相关性。结果显示:红外图谱及电镜扫描均证实了DTAB在BS-12两性膨润土表面的修饰;随着总修饰比例的增大,复配修饰膨润土对苯酚及菲的吸附量增大,在总修饰比例超出150%CEC后吸附量开始下降;总碳含量、层间距(d001)变化规律与总修饰比例成正比,比表面积变化规律与总修饰比例成反比,且变化幅度均在总修饰比例超出150%CEC后增大。相关性分析结果表明,复配修饰膨润土对苯酚和菲的吸附能力由总碳含量决定,BS/DTAB复配修饰膨润土对苯酚吸附模式为分配吸附,而对菲的吸附模式为分配吸附和表面吸附共存的模式。     

膨润土对镉污染土壤团聚体结构特征及有机碳含量的影响

通过4年田间原位钝化修复定位试验,研究施用膨润土钝化修复重金属镉污染菜地过程中,膨润土对土壤团聚体结构、稳定性以及有机碳含量变化特征。结果表明,与对照相比,施加膨润土后2～5 mm和5～8 mm粒径土壤团聚体数量增加,而2 mm的粒径团聚体数量则有所降低。投加膨润土提高了土壤团聚体稳定性,其几何平均直径(Geometric mean diameter, GMD)和平均质量直径(Mean weight diameter, MWD)分别增加9.57%～33.48%和4.74%～31.39%。与对照相比,全土和各粒径团聚体中有机碳含量随膨润土投加量增加而增加,而颗粒有机碳的含量则相反,最大降低了11.64%。投加膨润土提高了2～5 mm粒级团聚体对土壤有机碳含量的贡献率,0.5 mm粒级团聚体对土壤有机碳含量贡献率降低。投加膨润土后土壤烯烃类、烷烃类和酚类官能团含量有所增加,与对照相比,增加幅度分别为1.52%～4.55%、2.60%～36.28%和2.06%～10.98%。     

膨润土对星布罗肉鸡甲状腺组织结构影响的研究

应用光学显微镜和透射电镜技术,对实验组(添加膨润土)和对照组(不加膨润土)的鸡甲状腺的结构进行观察。结果表明,实验组鸡甲状腺有一系列功能旺盛的结构变化。     

Efficacy of bentonite clay in ameliorating aflatoxicosis in piglets fed aflatoxin contaminated diets

The efficacy of locally produced bentonite was evaluated with respect to ameliorating the adverse effects of aflatoxins (AF) in piglets fed AF contaminated diets. Forty eight piglets were randomly assigned to one of four treatments: 1) 0 g of bentonite and 0 μg AF/kg feed (control); 2) 4 g of bentonite plus 200 μg AF/kg feed (AF + Bento 4); 3) 5 g of bentonite plus 200 μg AF/kg feed (AF + Bento 5) and 4) 0 g of bentonite plus 200 μg AF/kg feed (AFA). Piglets in the AFA treatment had lower overall average daily weight gain (ADG), feed conversion efficiency, albumin (ALB) and total protein (TP) compared to the control diet, while mean serum leukocyte and enzyme activities (glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), gamma glutamyltransferase (GGT), alkaline phosphate (ALP) and lactic dehydrogenase (LDH)) were significant increased. The inclusion of bentonite at 0.4% or 0.5% in the AF contaminated diet restored the lower performance, feed efficiency and abnormal blood profiles of the piglets given AF and no differences between 0.4 and 0.5% inclusion of bentonite. The findings in the present study provide critically needed confirmation that bentonite has the ability to reduce the adverse effects of AF.     

膨润土对小白鼠精子畸形的影响

在小白鼠日粮中添加１ ．０ ％ 、２ ．０ ％ 、３ ．０ ％ 膨润土时, 对小白鼠精子畸形率影响不大（Ｐ＞ ０ ．０５） ,添加５ ．０ ％ 膨润土时,精子畸形率升高（Ｐ＜ ０ ．０１） ．