葡萄糖氧化酶对仔猪生长性能、养分消化率及肠道微生物和形态结构的影响 2015年9月25日

本试验旨在探讨葡萄糖氧化酶对仔猪生长性能、养分消化率及肠道微生物和形态结构的影响。试验采用体重（8．71±0．13） kg的“杜长大”三元杂交断奶仔猪300头,随机分成Ⅰ、Ⅱ、Ⅲ3个组,每个组5个重复,每个重复20头。试验Ⅰ组为对照组,饲喂基础饲粮;试验Ⅱ组在基础饲粮基础上添加0．1％的金霉素;试验Ⅲ组在基础饲粮基础上添加200 g／t的葡萄糖氧化酶。试验期28 d。结果表明,与试验Ⅰ组相比,试验Ⅱ、Ⅲ组平均日增重显著增加（P＜0．05）;试验Ⅱ、Ⅲ组饲粮中的干物质和粗蛋白质的消化率显著升高（ P＜0．05）;试验Ⅱ、Ⅲ组的胃和十二指肠食糜的pH显著下降（ P＜0．05）;试验Ⅲ组的十二指肠的绒毛高度以及绒毛高度／隐窝深度显著增加（P＜0．05）;试验Ⅱ、Ⅲ组胃和回肠中的大肠杆菌数量显著减少（P＜0．05）,乳酸菌数量显著增长（P＜0．05）,但盲肠中各组差异不显著（P＞0．05）。由此可见,饲粮中添加200 g／t葡萄糖氧化酶可以降低仔猪胃和十二指肠的pH和大肠杆菌的数量,增加乳酸菌的数量,改善十二指肠的绒毛高度,提高干物质和粗蛋白质的消化率,从而提高仔猪的生长性能。     

基于土地利用形态的城市防护人口基数计算方法 2013年9月18日

以信息化战争中人口防护的要求为目标,对快速城市化背景下防护人口基数的计算方法进行了探讨。在解析城市昼夜人口在分布数量上差异原因的基础上,构建了以就业人口为影响因素的城市防护人口基数的计算方法。根据城市就业人口分布与城市用地形态的关系建立了人口分布预测模型,引入了就业人口吸引权、用地规模、土地利用强度、区位系数作为模型的基本参数,给出了取值方法。以某市中心城区为实例对防护人口基数进行了计算,计算结果合理,可以供编制人防工程规划参考。     

概念格对象渐减维护与关联规则更新 2013年9月18日

研究概念格对象渐减维护与关联规则更新符合动态环境下概念格应用的需求。首先,提出了对象渐减时概念的更新原则和概念间关系调整方法,并在其基础上设计了概念格对象渐减维护算法。其次,采用了内涵缩减来获得概念蕴含的关联规则,从父子概念内涵差集的变化中发现了对象渐减时的内涵缩减更新规律。最后,获得了对象渐减时的关联规则更新方法。     

孙中山、南方政府与华盛顿会议———以代表问题为中心 2017年9月25日

北京政府自接到参加华盛顿会议的邀请后,即着手组织代表团,希冀以孙中山为首的南方政府派人共同赴会,但遭到严拒.代表问题一时成了舆论关注的焦点,社会各界从不同的立场出发,纷纷发表见解.会议期间,孙中山仍派出私人代表马素赴美,适机阐明南方政府的严正态度.不选派正式代表出席华盛顿会议,对急于寻求国际承认和列强支持的南方政府来说,失去了一次在国际舞台发声的机会,不能不说是一种损失.随后,孙中山对会议结果及日本帝国主义提出严厉批评,外交策略的抉择也发生了根本性变化.     

Effects of mixing on fed-batch fermentation of -ornithine

The effects of mixing on -ornithine fermentation were studied using an -arginine auxotrophic mutant of Brevibacterium ketoglutamicum ATCC 21092. Three different modes of fed-batch culture using two different impeller types were studied in a 7 l fermentor. The first two modes of fed-batch culture were carried out in a fermentor equipped with six-flat-blade disk-turbine impellers with top and bottom feeding. The third mode of fed batch culture was carried out using pitched-six-flat-blade disk-turbine impellers with top feeding. The titre of -ornithine increased up to 1.8 fold with bottom-feeding or when the pitched-six-flat-blade disk-turbine impellers were used compared to when the six-flat-blade disk-turbine impellers with top-feeding were used. It was observed that the mixing time of the limiting nutrients varied significantly depending on both the direction of feeding and the impeller type. Since the profiles of the specific rates of CO₂ evolution, oxygen and glucose uptakes were very similar for the three culture modes, it could be reasonably assumed that the microorganism exhibited similar growth rates for each mode used. However, different amino acid producing activities were observed in the three culture modes. From these results it is concluded that the productivity of -ornithine fermentation is significantly improved by shortening the mixing time of the limiting nutrient in the fermentor.     

Competitive amino acid transport between -tryptophan and other amino acids in Schizophyllum commune

In our study on nutritional requirement for the hyphal growth of Schizophyllum commune, we found that a Trp⁻ mutant could not grow in the -Trp-supplied medium in the presence of -Ser. Further growth studies showed that not only -Ser but also as many as 11 kinds of amino acid including -Ala, -Arg, -Asn, -His, -Leu, -Met, -Phe, -Ser, -Thr, -Tyr and -Val inhibited the growth of the Trp⁻ mutant in the -Trp-supplied medium. However, these amino acids did not inhibit the growth of a Trp⁺ strain. The inhibition of growth of Trp⁺ strain induced by a Trp analogue of 5-fluoro- -tryptophan (5FT), which was usually recovered by -Trp, was rescued by the same amino acids mentioned above. The exceptions were Gly and -Ile, which also recovered the growth inhibition induced by 5FT. These results indicate that the permease responsible for the Trp transport in S. commune might also be active to other amino acids. However, it is considered that the permease shows high affinity to -Trp and low affinity to other amino acids. As a result, the transport of -Trp and 5FT may be counteracted by other amino acids.     

Inhibition of mutagenic N-nitroso compound formation in sausage samples by using -ascorbic acid and α-tocopherol

In this study 24 samples of sausage with different amounts of nitrite, -ascorbic acid and α-tocopherol were prepared in order to determine the inhibitory effects of -ascorbic acid and α-tocopherol as reductants against formation of mutagenic N-nitroso compounds that form in cured meat products. These mutagenic N-nitroso compounds were extracted by phosphate buffer and ethylacetate. The mutagenicity of extracts were investigated by salmonella/microsome assay. The number of revertants indicated the N-nitroso compounds content. Among the Salmonella typhimurium strains tested, the revertants of S. typhimurium TA100 were significantly reduced (P<0.5) by 60% when reductants were added to the samples.     

Effects of Roxarsone on Performance,Toxicity, Tissue Accumulation and Residue of Eggs and Excreta in Laying Hens

In this study, we examined the effects of a high dosage of roxarsone in the diet on the performance, liver function, and its residue in liver, eggs and excreta of laying hens. Seventy-five 32-week-old layers were selected and randomly allocated into five dietary treatments with three replications for each treatment. Feeding periods were 4 weeks with an additional week for withdrawal. The experimental diets included 0, 11, 22, 44 or 88 mg kg^-1 arsenic from roxarsone, respectively. Dietary arsenic above 44 mg kg^-1 significantly decreased the egg production and feed intake of the layer (P < 0·05). Layers ceased to produce eggs after two weeks of feeding the 88 mg kg^-1 arsenic supplement diet. Where the enzyme activities in the serum, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) significantly increased. Also, the liver weight did not only significantly decrease (P < 0·05), but was also damaged on histological examination. Moreover, arsenic residues in the liver, eggs and the excreta significantly increased as dietary arsenic level was increased (P < 0·05). The serum enzyme activities of AST, LDH, CK returns to normal after a week of the drug withdrawal. Arsenic residues in liver, egg and excreta also significantly declined in the withdrawal period (P < 0·05). Furthermore, the hepatic cells were vacuolised from layers treated with 88 mg kg^-1 of arsenic. © 1997 SCI.     

黄腐酸对蛋鸡生产性能的影响

将2 000只400日龄健康海塞克斯蛋鸡随机分成2组,对照组饲喂基础日粮.试验组在基础日粮中添加0.5 g/d黄腐酸产品,研究其对蛋鸡生产性能的影响.结果表明:与对照组相比,试验组平均蛋重极显著提高7.40%、平均产蛋率极显著提高5.20%、料蛋比极显著降低15.07%、死亡率降低90%、破蛋率降低42.5%、平均耗料量降低4.04%.     

黄芪多糖对蛋鸡生产性能、生殖激素及 血液生理生化指标的影响

旨在研究饲粮中添加不同水平黄芪多糖(APS)对产蛋后期蛋鸡生产性能、生殖激素和血液生理生化指标的影响。随机选取27周龄健康、体质量相近、产蛋率相近的产蛋后期海兰褐壳蛋鸡360只,随机分为3个处理,每处理6个重复,每个重复20只。处理Ⅲ组为对照组,饲喂玉米—豆粕型基础饲粮,处理Ⅰ、Ⅱ组为试验组,分别饲喂在基础饲粮中添加200和100 mg/kg黄芪多糖的试验饲粮,预试期1周,试验期49 d。添加黄芪多糖可显著提高产蛋率,降低料重比,提高生产性能。黄芪多糖组显著或极显著地(P0.05或P0.01)提高了FSH、LH、E_2、IGF-Ⅰ、T_4、Pt含量;多糖高剂量组血清TG、AST、ALT显著或极显著低于对照组(P0.05或P0.01);GLU、HDL、ALP、Ca~(2+)和P含量显著或极显著高于对照组(P0.05或P0.01)。试验结果表明,黄芪多糖可提高产蛋后期母鸡的生殖激素水平,有利于改善产蛋后期母鸡的卵巢功能,促进卵泡发育与排卵,提高其产蛋性能;并具有一定的降血脂的作用。     

载锌沸石对蛋鸡生产性能、血清激素水平及抗氧化功能的影响

旨在研究载锌沸石对蛋鸡生产性能、血清生殖激素水平及抗氧化功能的影响。将648只31周龄蛋鸡随机分为6组,每组设6个重复,每个重复18只。对照组饲喂基础日粮中添加Zn SO4的对照日粮(锌添加量为80 mg/kg),抗生素组在上述对照日粮中添加40 mg/kg杆菌肽锌,试验1、2、3、4组分别在基础日粮中添加0.11%、0.23%、0.34%、0.46%载锌沸石(锌含量分别为20、40、60、80 mg/kg)。结果表明:与对照组相比,日粮中添加0.23%、0.34%、0.46%载锌沸石可显著降低软破蛋率(P0.05)。在试验第4周,添加不同剂量载锌沸石均提高了血清中促卵泡素水平(P0.05),在试验第8周时0.46%载锌沸石组可提高血清雌二醇(E2)水平(P0.05),0.34%载锌沸石组在试验第4周和8周时血清总超氧化物歧化酶(T-SOD)活性显著高于对照组(P0.05),而0.23%、0.46%载锌沸石组分别在试验第4周和8周时血清丙二醛含量显著降低(P0.05),0.46%载锌沸石组蛋鸡肝脏T-SOD活性、铜锌超氧化物歧化酶活性显著高于对照组(P0.05),0.23%、0.34%、0.46%载锌沸石组肝脏过氧化氢酶(CAT)活性、谷胱甘肽过氧化物酶(GSH-Px)活性显著提高(P0.05);与抗生素组相比,0.46%载锌沸石组显著提高了血清中E2水平和试验第8周血清中促黄体素水平(P0.05),日粮中添加不同剂量载锌沸石在试验第4周时均显著提高了血清中GSH-Px活性和还原型谷胱甘肽含量(P0.05),0.23%载锌沸石组肝脏CAT活性、GSH-Px活性显著提高(P0.05)。试验结果提示,载锌沸石能作为一种可添加的锌源应用于蛋鸡饲料中,并可替代杆菌肽锌,且以添加0.34%、0.46%载锌沸石为宜。     

植物甾醇对蛋鸡产蛋后期生产性能、鸡蛋胆固醇含量及血清生殖激素水平的影响

选用1 500羽520日龄伊莎褐商品蛋鸡,随机分成5组,每组6个重复,第1组为对照组,试验组日粮中分别添加5、10、20和40 mg/kg植物甾醇,研究植物甾醇对蛋鸡产蛋后期生产性能、鸡蛋胆固醇含量及血清生殖激素水平的影响.结果表明,与对照组相比,添加植物甾醇对蛋鸡产蛋后期的平均蛋重及产蛋率均无显著影响,但能降低死淘率,20 mg/kg的植物甾醇添加量效果较好;降低了蛋黄的胆固醇含量;试验前期,试验组血清的生殖激素水平无显著变化,试验后期,第2和5组的雌二醇(E2)有显著提高,第2和4组的促黄体素(LH)明显降低,试验组的促卵泡素(FSH)及促乳素(PRL)均无显著影响.     

复合微量元素对蛋鸡生产性能的影响

试验选1日龄罗曼褐壳蛋鸡525只,随机分为5个组(A、B、C、D、E组),分4阶段饲养,共33周。各阶段在其相同的基础日粮(均补充I0. 4mg/kg和Se0. 3mg/kg)中分别添加5个水平(A、B、C、D、E组按NRC标准添加的量分别为0、0. 5、2、3和需要的最高倍数)的复合微量元素(Fe、Cu、Zn、Mn)。结果表明:①育雏期日增重A组显著高于B、C、E组(P<0. 05),料重比A组显著低于D组(P<0. 05);②育成前期所有观测指标差异均不显著(P>0. 05 );③育成后期A组的末重比B组高3. 13%,日增重比C组高6. 74%,料重比比C组低7. 24%;④产蛋前期平均产蛋率A组显著低于其它各组(P<0. 01),日产蛋量D组最高,并显著高于A组(P<0. 05),料蛋比A组比D组高4. 18%。综合分析表明,育雏期、育成前期基础日粮中的微量元素已满足需要,不需额外添加,育成后期和产蛋前期按照D组方案添加较好。     

鱼油替代菜籽油对蛋鸡生产性能及脂质代谢的影响

试验共设四个组，对照组含3％菜油，试验组分别含2％菜油＋1％鱼油、1％菜油＋2％鱼油和3％鱼油，研究日粮鱼油替代菜籽油对蛋鸡产蛋性能、蛋品质和脂质代谢的影响。结果表明，蛋黄中ALA、DHA含量以2％鱼油添加组最高，分别比对照组提高32．88％（P〈0．05）和22．49％（P〉0．05），EPA含量以1％鱼油添加组最高，比对照组提高13．48（P〈0．05）；添加鱼油组蛋黄TC含量升高（P〉0．05），TG变化不明显，MDA含量升高（P〉0．05）；血清TC含量升高，以3％鱼油添加量组最高，比对照组提高3．55％（P〈0．05），2％、3％鱼油添加组TG含量降低，分别比对照组下降12，52％（P〉0．05）和51．18％（P〈0．05）；血清HDL—C含量升高，LDL—C含量降低，SOD、MDA含量有所降低，蛋重以2％和3％鱼油添加组显著低于对照组（P〈0．05），蛋壳强度分别比对照组提高13．79％（P〉0．05）、41．72％（P〈0．05）和32．37％（P〉0．05）。研究表明，蛋鸡日粮中添加鱼油可以提高ω-3PUFA在蛋黄中的沉积，影响机体的脂质代谢，同时伴随脂质过氧化物合成增加，但对产蛋性能无明显影响。综合各种指标，蛋鸡日粮中以2％的鱼油添加量为佳。     

大米蛋白肽对热应激时蛋鸡生产性能和相关生理生化指标的影响

研究在热应激的情况下,大米蛋白肽对蛋鸡生产性能和血液生理生化指标的影响.选择健康无病,体重相近的罗曼蛋鸡320只,随机分为4组,每组80只,下设4个重复,每个重复20只鸡.1组为对照组,2组、3组、4组为试验组,1组喂基础日粮,2、3、4组分别饲喂含1％、1.5％和2％的试验日粮.结果:在热应激条件下,添加1.5％～2％的大米蛋白肽能明显提高鸡的产蛋率、采食量、血液中的总蛋白、总脂和甲状腺素浓度(P＜0.05),显著降低产蛋鸡的料蛋比、血液中的血糖、醛固酮和皮质醇(P＜0.05),还能一定程度地降低鸡的死亡率.表明:在夏季,使用1.5％～2％的大米蛋白肽有利于提高蛋鸡的生产性能及改善相关的生理生化指标.     

高温下不同维生素A水平对蛋鸡影响的研究

试验研究高温下 (32℃ )不同维生素A(VA)添加水平 (30 0 0IU/kg和 90 0 0IU/kg)对蛋鸡的生产性能、某些血液生化指标和免疫性能的影响。结果表明 ,高温下不同VA添加水平对蛋鸡的采食量 (P <0 .0 5 )、产蛋率 (P <0 .0 5 )、血糖 (P <0 .0 1)有显著影响 ,但对料蛋比、蛋壳厚度、蛋重、尿酸、抗体水平无显著影响 (P >0 .0 5 )。     

The Influence of Feeding Yellow-, Green- and Brown-Seeded Peas on Production Performance of Laying Hens

Two experiments were conducted to evaluate the feeding value of yellow-, green- and brown-seeded peas as protein and energy supplements in laying hen diets. In experiment 1, all three types of peas were included in laying hen diets at 0, 200, 400 and 600 g kg^-1 replacing wheat and soya bean meal. Layers fed diets containing peas at 200 g kg^-1 produced more (P⩽0·05) eggs, had higher (P⩽0·05) egg mass output and better (P⩽0·01) feed conversion than those fed the wheat soya bean meal control diet. With 400 g peas kg^-1 in diets, egg production, egg mass and feed conversion were similar (P⩾0·05) to the control diet. Total replacement of soya bean meal with peas (600 g peas kg^-1 in diets) reduced (P⩽0·01) egg production, egg mass and feed conversion. A progressive (P⩽0·01) improvement in yolk colour as the level of peas in the diet increased was observed. Shell quality decreased (P⩽0·05) with increasing levels of yellow or brown peas in the diets, however, it seemed not to be affected by green peas. Daily feed intake, egg weight and mortality rates were not affected by dietary treatments. The influence of feeding diets containing yellow or brown peas supplemented with varied levels of methionine on production performance of laying hens was investigated in experiment 2. The dietary treatments consisted of a 400 g kg^-1 yellow or brown pea diet supplemented with three levels of methionine to 100, 115 and 130% of the NRC requirements. Methionine supplementation to either 15 or 30% above NRC requirement for laying hens had no significant (P⩾0·05) effect on all production parameters. It can be concluded that the inclusion of yellow, green or brown peas into laying hen diets up to 400 g kg^-1 does not affect production performance. The NRC recommendation of methionine requirement for laying hens is adequate to support maximum egg production for diets containing moderate quantities of peas. © 1997 SCI.