Stress parameters and immune response of layers under different cage floor and density conditions

The aim of the experiment was to investigate the effects of cage floor and cage density on stress parameters of laying hens. A total of 162 brown laying hens (Hyline Brown), aged 34 weeks, were used in the experiment. Compact-type battery cages, with three floors, were used. Hens were allocated as one, three or five hens in each of 18 cages to obtain three different cage density groups of 1968, 656 and 393.8 cm² floor area per hen, respectively. The same number of cages with different cage density were allocated to three different battery floors (first floor=top, second=middle, third=bottom) systematically. Values for body weight, mortality rate, egg weight, egg production, egg quality characteristics, egg yolk cholesterol content, the levels of blood plasma corticosterone, serum glucose, total cholesterol and triglycerides, the ratio of heterophils to lymphocytes (H-L ratio), antibody titers, claw length score, foot health score, plumage score and throat skin injuries were taken as indicators of stress. The values for egg weight (P<0.01) at the first floor were greater than the other floor levels. The group with five hens per cage had significantly lower mean estimates (P<0.01) than other groups with respects to body weight (P<0.001), egg production (P<0.001), egg weight (P<0.001) and plumage score (P<0.01), while significantly higher mean estimates for egg albumen index (P<0.01), Haugh unit (P<0.01), serum glucose (P<0.001), and H-L ratio (P<0.001). Serum cholesterol was higher in cages with one hen than that with five hens, whereas plasma corticosterone was lower. Antibody titers in cages with one hen was similar to that with three or five hens; however, those with three hens had higher titers than those with five hens. Values for egg breaking strength, yolk index, egg cholesterol content, and foot health score were not affected by cage density or floor. The results suggest that the allocation of three hens per cage had no measurable effect on health and welfare.     

Regulation of‘Tiao Gan Fang Yao’on neuroendocrine-immuno-function of bandage-stressed rats

AIM: To investigate the regulation of ‘Tiao Gan Fang Yao’(TGFY) on neuroendocrine-immuno-function of bandage-stressed rat . METHODS:The stressed rat model was made by bandage. RIA was adopted to measure the function of hypothalamus-pitutary-adrenal gland axis (HPAA) of stressed rat. Meanwhile, the immunity of stressed rat and the regulation of TGFY were observed.RESULTS:Bandage stress increased the contents of serum corticosterone(CORT), and ACTH, and hypothalamus corticotropin releasing hormone (P＜0.01 or 0.05), which suggested that the excitability of HPAA was enhanced. In addition, bandage stress reduced spleen lymphocyte proliferation (P＜0.01) and decreased H₂O₂ releasing from the macrophages significantly (P＜0.01). While TGFY could decrease HPAA excitability of bandage-stressed rat and strengthen its immunity. CONCLUSION:TGFY could regulate disorder of neuroendocrine-immuno-function of bandage-stressed rat.     

番茄育种研究主要进展—文献综述

对近年来国内外番茄育种研究在抗病,抗客品质改良方面所获得的主要进展进行了综述,并就我国今后番茄育种的主要研究方向进行了讨论。     

重金属致植物矿质营养元素代谢异常的生理效应

重金属胁迫会导致植物体细胞的矿质营养元素缺乏、代谢过程紊乱,甚至可引起植物的死亡。综述了重金属导致植物体的某些矿质元素代谢异常的生理效应。     

基于局部综合法的非零正传动弧齿锥齿轮副设计

利用局部综合法对非零正传动弧齿锥齿轮副进行大重合度加工参数设计,克服了非零正传动由于啮合角增大而使得重合度降低的不足。通过实例与常规设计的结果进行仿真与应力分析对比,结果表明,在同样的载荷条件下,新设计比常规设计的小轮最大齿根拉伸应力减小27.6%,最大齿根压缩应力减小23.5%,最大齿面接触应力减小6.5%,同时大轮的齿根应力也有所降低,使得齿轮副具有更高的寿命和可靠性。     

基于激光热应力法的薄膜蠕变性能评估方法

采用单脉冲激光在薄膜表面进行局部加载,对薄膜在受热区域、冷热接合部及与基体连接界面产生的热应力、热应变及应力松弛进行理论分析,研究薄膜的蠕变机制和非弹性变形的热力学响应。分析结果表明,薄膜受高温及冷却退火作用都会产生应力松弛;冷却退火还会形成拉应力,薄膜裂纹由拉应力过大引起,薄膜的蠕变性能是薄膜断裂前的热力学行为,由应力的性质和大小决定,用激光热应力法可以实现对薄膜性能的评估。     

水分胁迫对结球白菜光合特性的影响

以3个结球白菜品种新早56、新乡小包、北京小杂为试材,采用盆栽方式模拟田间试验,人为设置4个土壤相对含水量处理,研究了水分胁迫对大白菜光合特性的影响。结果表明,随着土壤水分胁迫程度的增加,白菜叶片净光合速率、蒸腾速率、气孔导度均逐渐下降,光合速率高低顺序表现为新早56>新乡小包>北京小杂,而胞间CO2浓度则品种间无显著差异,表明在水分胁迫下非气孔因素是导致白菜叶片光合速率下降的主要原因,同时说明新早56的抗旱性强于新乡小包和北京小杂。     

土壤重金属镉、铅、锌胁迫对小白菜生长状况的影响

[目的]采用添加外源重金属和盆栽试验的方法,研究土壤重金属胁迫对小白菜生长状况及生物量的影响.[方法]通过对土壤添加外源Cd、Pb、Zn进行室内盆栽试验,设置不同浓度的胁迫试验,研究不同浓度重金属胁迫作用下小白菜生长状况和生物量的影响.[结果]在生长初期,Cd、Pb、Zn胁迫对小白菜生长并未表现出明显抑制作用,小白菜生...     

Urinary catecholamine and metanephrine to creatinine ratios in healthy dogs at home and in a hospital environment and in 2 dogs with pheochromocytoma

BACKGROUND: Measurement of high concentrations of urine catecholamines and metanephrines is useful in diagnosing pheochromocytoma in humans. Stress increases catecholamine excretion in urine. HYPOTHESIS: Stress of a hospital visit increases urinary catecholamine and metanephrine excretion in dogs. ANIMALS: Fourteen clinically normal dogs, 2 dogs with pheochromocytoma. METHODS: Voided urine samples were collected by the owners 7 days before (t-7), during the hospital visit immediately after diagnostic procedures (t0), as well as 1 (t1) and 7 days (t7) after the hospital visit. Urine catecholamine and metanephrine concentrations were measured using high-pressure liquid chromatography and expressed as ratios to urine creatinine concentration. RESULTS: In client-owned dogs epinephrine and norepinephrine ratios at t0 were significantly higher compared with ratios at t7. Metanephrine and normetanephrine ratios at t-7, t0, and t1 did not differ significantly from each other; however, at t7 they were significantly lower compared to values at t-7. In staff-owned dogs no significant differences were detected among the different collecting time points for any variable. Metanephrine and normetanephrine ratios were significantly higher in client-owned dogs compared to staff-owned dogs at t-7, t0, and t1 but not at t7. CONCLUSIONS AND CLINICAL IMPORTANCE: Stress associated with a hospital visit and with the sampling procedure causes increases in urine catecholamine and metanephrine excretion. Urine collection for the diagnosis of pheochromocytoma probably should take place at home after adaptation to the sampling procedure.     

加氢反应器接管补强部位的应力分析

以应力分析法和ANSYS有限元法分别对加氢反应器接管补强部位进行了应力分析,结果表明:最大应力出现在反应器上封头与接管的内壁交界处。通过分析得知,用ANSYS软件分析反应器接管补强部位的应力比传统应力分析法更直观方便,计算相对更精确省时。