哺乳期藏猪肠道N-乙酰谷氨酸合成酶的表达特性

 【目的】探讨藏猪仔猪肠道N-乙酰谷氨酸合成酶(NAGS)在哺乳期的表达变化。【方法】克隆藏仔猪的NAGS基因,并制备其多克隆抗体,分别采用实时定量PCR和Western blotting方法检测1、7、21、28和35日龄的哺乳藏仔猪空肠和回肠中NAGS mRNA的表达水平和蛋白丰度。【结果】7～35日龄藏仔猪空肠与回肠的NAGS mRNA表达水平(P＜0.05)和蛋白丰度(P＜0.01)均随日龄增长呈线性下降趋势。【结论】哺乳期仔猪的空肠和回肠NAGS mRNA和蛋白表达水平随日龄增长而下降,可能是内源性精氨酸合成减少的一种重要机制。     

干理想大根地膜覆盖栽培技术研究

采用裂区设计,研究了播种期和地膜覆盖及两者交互效应对干理想大根产量的影响,确立了地膜覆盖条件下的适宜播期,并对增产机理进行了初步探索。结果表明:在郯城县气候条件下,实施地膜覆盖栽培干理想大根的最佳播种期为8月22日;地膜覆盖栽培可以改善土壤的物理性状,使出苗期土壤表层(0~10 cm)含水量增加1.6个百分点、采收期土壤容重较对照低0.05~0.10 g/cm3,使干理想大根单株产量增加11%,同时对产量相关性状和产品加工品质也具有同步促进作用。     

苏铁主干快速形成多头景观的技术研究

通过对苏铁主干自然形成多头现象的研究后,于2000年—2002年在宜春学院园林花卉基地对苏铁主干或顶部进行嫁接和劈顶试验,效果明显,其嫁接成活率达82.9%以上,劈顶后顶部新芽体发生量平均每株达5—5.43个,最多达10个。     

A RVI/LAI-reference curve to detect N stress and guide N fertigation using combined information from spectral reflectance and leaf area measurements in potato

More user-friendly methods are needed to detect crop N status/stress and guide the timing of in-season N application. In the current study, a reference curve method of detecting N stress was proposed to remedy practical problems of methods that require leaf sampling or maintaining a N sufficient strip in the field. The reference curve method was derived from the integrated information of ratio vegetation index (RVI) and leaf area index (LAI), which were obtained from field experimental potato crops. Different N treatments received 42 kg N ha⁻¹ at planting and, subsequently, the rest of N was applied during the season. The total N ranged from 0 to180 kg N ha⁻¹. RVI and LAI from the economically optimum 180 kg N ha⁻¹ treatments were used to derive the reference curve. RVI and LAI from 180 kg N ha⁻¹ treatment had a high (R² = 0.97) correlation and were best fitted with a 2nd order polynomial function, which was independent of season. The treatments where N fertigation was stopped before reaching 180 kg N ha⁻¹ started to deviate from the 95% confidence interval of the reference curve about 10 days after N-fertigation was stopped. This corresponded to 10–20 kg ha⁻¹ difference in total plant N uptake between reference and the N deprived treatments, implying that a deviation from the reference curve occurred for small N deficits. Besides, running crop simulation model to alert for impendent N stress closely corresponded to the reference curve and was recommended as a second management tool. Therefore two tools are hereby made available to guide supplementary N-fertilization. These will be helpful in regional potato production for diagnosis of N status, and allow discrimination between situations of sub-optimal and optimal N supply.     

柑橘裂果的种类、特点及其影响因素

柑橘裂果是生产上的重要生理性病害，根据开裂方式的不同可将柑橘裂果分为外裂和内裂两大类。本文主要从裂果种类、特点、影响因素和克服措施等方面介绍裂果，以系统了解柑橘裂果问题。     

Hygiene management in newborn individually housed dairy calves focusing on housing and feeding practices

In calf rearing, the first weeks of life are critical and associated with the highest mortality due to enteric and respiratory diseases. A well-implemented hygiene management can help to protect calves’ health preventively by reducing the load of pathogenic bacteria and interrupting infection chains. The aim of this study was to identify deficiencies in hygiene management of individually housed dairy calves by surveying current practice and examining feeding and housing equipment with different hygiene indicators. On 11 farms, different locations in 2 pens or hutches for individual calf rearing prepared for restocking and 2 feeding buckets per farm, including the inner and outer surfaces of artificial teats, were visually scored for cleanliness and sampled with swabs (housing equipment: n = 167; feeding equipment: n = 120). The sanitation of floors was tested with sock samples (n = 41). A total of 328 samples were analyzed for adenosine triphosphate (ATP) and protein residues, aerobic total viable count (TVC), total coliform count (TCC), Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum β-lactamase-producing bacteria (ESBL), and Salmonella spp. After evaluation of these results, the farmers were informed about the findings and trained on improvement in hygiene management personally. The sampling was repeated after 1 year to detect possible changes in hygiene management. The highest bacterial loads (TVC, TCC, and E. coli) were observed in feeding equipment, especially the inner teat of milk feeding buckets. Environmental samples, primarily the sidewalls and back walls of tested pens and hutches, exhibited the lowest bacterial counts and ATP and protein residues. All samples were negative for MRSA and Salmonella spp. In 10.5% of all samples, ESBL was detected, and in 6.8%, ESBL E. coli was detected, predominately in sock samples, followed by feeding equipment samples. Training in hygiene management showed only limited effects. In conclusion, there is still great potential to improve the implementation of hygiene measures in individual calf housing. In particular, more attention should be paid to the cleaning of feeding buckets and artificial teats, as this is a simple means of interrupting the possible spread of pathogens among calves.     

西南玉米区主推品种耐密性比较研究（英文）

采用裂区试验,以密度和品种为试验因子,研究了11个西南玉米区主推玉米品种产量和主要农艺性状,比较不同品种的耐密性。结果表明:1密度间、品种间、密度与品种互作差异均达极显著水平;2参试品种在高种植密度(6.45万株/hm2)下的平均产量显著高于其在低种植密度(4.95万株/hm2)下的产量,增产10.37%;3依据各品种的增密后的表现将品种分为高产增密增产型、高产增密不增产型、低产增密增产型、低产增密不增产型4个类型。     

大尾寒羊哺乳羔羊能量代谢规律的研究

本文通过饲养试验、消化代谢试验和屠宰试验等方法，研究大尾寒羊哺乳羔羊的能量代谢规律及需要量，试验证明，羔羊对母乳的能量消化率为95．5％，能量代谢率(ME／GE)为94．6％，羔羊对本试验日粮能量消化率，少量补饲期为80．9％，大量补饲期为73．7％，全哺乳期羔羊每千克活体增重所需净能为6027KJ，补饲期平均为7949KJ／kgLWG，羔羊全哺乳期，少量补饲期，大量补饲期生产代谢能转化效率(Kpf)分别为0．708，0．53和0.29，代谢能需要量为：全哺乳期(0～23d) MER=475W^0.75 1．41NEg(或8.5△W)；少量补饲期(23-55d)MER=475W^0.75 1．89NEg(或15．0△W)；大量补饲期(55—80d)MER=475W^0.75 3．45NEg(或27．4△W)；MER,NEg：KJ；△W；g。     

精胺对哺乳仔猪小肠黏膜二糖酶比活力的影响

试验研究了哺乳仔猪口服精胺0、0.1、0.2、0.3、0.4、0.5 mmol·kg-1BW对小肠黏膜二糖酶比活力的影响。试验选取来自6窝11 d哺乳仔猪36头进行试验。试验采用完全随机区组设计,以窝别为区组,每头仔猪为试验重复,不同精胺剂量为处理,将同窝选取的6头试验仔猪随机分配到一个精胺剂量处理组中。口服精胺1次·d-1,持续3 d。试验结果显示,精胺没有改变仔猪生长性能(P0.05),却显著增加了十二指肠和空肠黏膜重量(P0.05)。增加口服精胺剂量线性提高了十二指肠和空肠黏膜麦芽糖酶和蔗糖酶比活力(P0.05),降低了乳糖酶比活力(P0.01)。试验结果表明,口服精胺改变了肠道黏膜二糖酶活性,提示精胺有促进幼龄哺乳仔猪小肠发育和成熟的效果,且适宜剂量为0.3~0.5 mmol·kg-1BW·d-1。     

分解刚度法在矩形网架结构弯曲和振动分析中的应用

把矩形网架结构(正放类网架、三向类网架)简化为夹层板,采用考虑剪切变形的具有3个广义位移的平板弯曲理论进行分析。利用分解刚度法对5类网架(正放四角锥网架、两向正交正放网架、正放抽空四角锥网架、三角锥网架和三向网架)进行了静力分析和固有振动分析,给出了简便实用的计算公式。通过与有限元法分析结果的对比,表明了分解刚度法作为一种简化的计算方法,其精度是比较高的,绝大多数的误差都小于5％,是可以应用于工程结构设计的一种有效方法。此外,与其它的简化计算方法相比它的精度比较高而且计算过程大大简化了。