香蕉茎秆纤维提取机刀片的分析和优化设计—基于SolidWorks

为减小香蕉茎秆纤维提取机刀片工作时的最大应力,增大其安全系数,利用SolidWorks软件对刀片进行三维建模,运用软件的Simulation插件分析刀片的应力、应变云图,并对刀片相关尺寸进行优化设计。优化结果显示,刀片的最大应力由68.58MPa下降到49.33MPa,下降约28%;刀片的最小安全系数由3.21上升到4.47,增加了约1.4倍;刀片的质量由0.702kg下降到0.698kg,达到了优化的目标。     

育种咨询系统中的水稻杂交后代性状预测

杂交育种是一个很复杂的组合过程。由于指导育种的遗传学原理还远不够完善,因此,在实践中更多的是依赖育种家的经验和技巧,从而造成了育种工作中一定程度上的盲目性。为了提高育种效率,有必要发展一套为育种工作服务的咨询系统。利用它协助育种家收集数据、分析育种过程。本文重点阐述水稻杂交咨询系统研制中的杂交后代性状预测方法及原理。     

Effects of dietary supplementation of emulsifier and carbohydrase on the growth performance,serum cholesterol and breast meat fatty acids profile of broiler chickens

A total of 540 2‐day‐old male Ross 308 broilers were used in a 35‐day experiment and were randomly divided into five treatments: (i) NC (low energy); (ii) PC (high energy diet); (iii) P1 (NC + 0.1% carbohydrases); (iv) P2 (NC + 0.05% emulsifier); and (v) P3 (NC + 0.1% carbohydrases + 0.05% emulsifier). From days 0 to 21, body weight gain in PC and P3 treatments increased (P < 0.05) compared with NC treatment. The chicks fed PC, P1, P2 and P3 improved (P < 0.05) feed conversion ratio compared with the NC treatment throughout the whole experiment. Abdominal fat weight was heavier (P < 0.05) in PC, P2 and P3 treatments than in NC and P1 treatments. On day 35, serum total cholesterol and low density lipoprotein cholesterol concentration were higher (P < 0.05) and high‐density lipoprotein cholesterol was lower (P < 0.05) in NC and P2 treatments than in PC, P1 and P3 treatments. The concentration of oleic acid, linoleic acid and total unsaturated fatty acids were highest (P < 0.05) in PC than in the other treatments. In conclusion, the results indicate that low energy density diet had lower growth performance, while the inclusion of emulsifier and carbohydrases in low energy diets can partially improve growth performance.     

Effects of water‐misting sprays with forced ventilation on post mortem glycolysis,AMP‐activated protein kinase and meat quality of broilers after transport during summer

Effects of water‐misting sprays with forced ventilation on post mortem glycolysis, adenosine monophosphate‐activated protein kinase (AMPK) and meat quality of broilers after transport during summer were investigated in the present paper. A total of 105 mixed‐sex Arbor Acres broilers were divided into three treatment groups: (i) 45 min transport without rest (T); (ii) 45 min transport with 1 h rest (TR); and (iii) 45 min transport with 15 min water‐misting sprays with forced ventilation and 45 min rest (TWFR). Each treatment consisted of five replicates with seven birds each. The results indicated that the water‐misting sprays with forced ventilation could mitigate the stress caused by transport under high temperature conditions during summer, which reduced the energy depletion in post mortem Pectoralis major (PM) muscle. This resulted in a higher energy status compared to the T group, which would decrease the expression of phosphorylation of AMPK (p‐AMPK). Furthermore, decreased the expression of p‐AMPK then slowed down the rate of glycolysis in post mortem PM muscle during the early post mortem period, which in turn lessened the negative effects caused by transport on meat quality. In conclusion, water‐misting sprays with forced ventilation may be a better method to control the incidence of the pale, soft and exudative meat in broilers.     

Improved development of somatic cell cloned bovine embryos by a mammary gland epithelia cells in vitro model

Previous studies have established a bovine mammary gland epithelia cells in vitro model by the adenovirus-mediated telomerase (hTERT-bMGEs). The present study was conducted to confirm whether hTERT-bMGEs were effective target cells to improve the efficiency of transgenic expression and somatic cell nuclear transfer (SCNT). To accomplish this, a mammary-specific vector encoding human lysozyme and green fluorescent protein was used to verify the transgenic efficiency of hTERT-bMGEs, and untreated bovine mammary gland epithelial cells (bMGEs) were used as a control group. The results showed that the hTERT-bMGEs group had much higher transgenic efficiency and protein expression than the bMGEs group. Furthermore, the nontransgenic and transgenic hTERT-bMGEs were used as donor cells to evaluate the efficiency of SCNT. There were no significant differences in rates of cleavage or blastocysts or hatched blastocysts of cloned embryos from nontransgenic hTERT-bMGEs at passage 18 and 28 groups (82.8% vs. 81.9%, 28.6% vs. 24.8%, 58.6% vs. 55.3%, respectively) and the transgenic group (80.8%, 26.5% and 53.4%); however, they were significantly higher than the bMGEs group (71.2%, 12.8% and 14.8%), (p < 0.05). We confirmed that hTERT-bMGEs could serve as effective target cells for improving development of somatic cell cloned cattle embryos.     

Nanosize of zinc oxide and the effects on zinc digestibility,growth performances,immune response and serum parameters of weanling piglets

The aim of this study was to investigate the effect of dietary supplementation of nanosize zinc on zinc digestibility, growth performances, immune response and serum parameters of weanling piglets. Ninety‐six LYD weanling piglets were assigned to control, zinc oxide (ZnO), organic‐Zn (Zn‐methionine) and nanosize ZnO (nano‐Zn) groups with four replicates. The zinc was at the 120 mg/kg level in the treatment group's diet, while the control group's was 80 mg/kg Zn. The experiment results indicated that the nano‐Zn and organic‐Zn groups had significantly higher Zn digestibility compared to the ZnO and control groups. For the immune response traits, the IgG level and goat red blood cells (GRBC) antibody titer were nano‐Zn and organic‐Zn>ZnO>control; in the phytohemagglutinin (PHA) challenge test result, nano‐Zn>organic‐Zn>ZnO>control; in regard to the γ‐globulin level, nano‐Zn and organic‐Zn>ZnO and control, with significant difference between groups. In the serum parameters aspect, serum Zn concentration in nano‐Zn and organic‐Zn groups were higher than in the ZnO and control groups, serum growth hormone concentration was increased in the nano‐Zn group than in the other groups. In conclusion, nanosize zinc oxide for dietary supplementation can increase zinc digestibility, serum growth hormone levels and carbonic anhydrase activity and enhance the immune response of weanling piglets.     

麦草畏、水杨酸对西洋参成熟种胚体细胞胚发生的影响

以西洋参成熟种胚为试材,以不加激素和添加0.5mg/L 2,4-D的MS培养基为对照,研究了不同浓度(0.05~2.00mg/L)麦草畏、水杨酸对西洋参体胚发生的影响。结果表明:未添加激素的空白培养基没有愈伤和体胚发生;在附加2,4-D的培养基中愈伤和体胚发生率为100%;5个浓度的麦草畏和水杨酸均能诱导出体胚,其中1.00mg/L麦草畏的效果最佳,体胚发生率为56.60%,水杨酸处理下体胚发生率最高为7.50%;在各种浓度的水杨酸中种胚生长量比对照小且褐化严重。说明麦草畏、水杨酸均可诱导西洋参成熟种胚体细胞胚发生,诱导能力2,4-D麦草畏水杨酸;水杨酸对种胚生长有抑制作用。     

辽东地区立地条件对林下种植大叶芹类胡萝卜素含量的影响

在充分调查辽东地区大叶芹生长环境的基础上,以大叶芹为试材,研究了不同立地条件和环境因子对大叶芹生长的影响,以期筛选出可获得高品质大叶芹的栽植模式。结果表明:林型、坡向、坡位和坡度均对大叶芹的类胡萝卜素含量影响极显著;林下大叶芹类胡萝卜素含量明显高于全光坡耕地生长的大叶芹类胡萝卜素含量;样地处在人工落叶松林下、半阳坡、坡度为15°~20°的上坡时,其大叶芹中类胡萝卜素的含量最高。     

野生蝉花液体菌种培养条件的优化

以野生蝉花菌种为试材,采用液体培养法,研究了碳源、氮源、微量营养和pH对野生蝉花菌种生长的影响,以期为标准化、规模化、产业化人工栽培蝉花提供优质种源。结果表明:将野生蝉花菌株接种到液体培养基中,在19℃,转速120r·min-1恒温振荡摇床内培养,蝉花菌种的最适液体培养基组分为可溶性淀粉20g,奶粉10g,磷酸二氢钾0.5g,硫酸镁1g,维生素B1210片,水1 000mL,最适pH 5.0~6.0。