木聚糖酶在肉仔鸡日粮中的应用

本文就木聚糖酶的来源、理化性质及其在肉仔鸡生产中的应用作一综述。     

The Dynamic of Maternal Antibody Against Enteritis Virus in Newborn Minks and Immune Efficacy of the Subunit Vaccine

The purpose of this study was to investigate the dynamic of mink enteritis virus (MEV) maternal antibody and the immune effects of subunit vaccines.The offspring of immunized female mink were studied,serum of 21,30,45 and 60 days old mink were collected to determine the HI titer of maternal antibody of MEV.25 healthy minks aged 47~52 days were selected to be inoculated with MEV genetic engineering subunit vaccine,and then blood samples were collected 14 d before and after immunization to determine MEV HI titer.The clinical symptoms and the titer of feces HA of mink enteritis virus were observed 14 d after immunization.Dying and surviving minks were euthanized 14 d after challenge,the duodenum,jejunum and ileum were collected for histopathological observation and immunohistochemical detection.The results showed that the MEV HI of the offspring of immunized female mink decreased gradually with the increase of day age,it was higher at 21 d of age,the MEV HI titer of some minks at 45 d was <1:32 and ≤ 1:4 at 60 d.The MEV HI titer of the control mink was not higher than 1:4 on 14 d after the preparation of qualified vaccine,while it was increased to 1:64~1:512 in immune group.Challenge protection tests showed that the immuned minks were 100% resistant to the attack of mink enteritis virus,and there was no abnormality in the mink's mental state,diet and feces,the HA titer of feces matter after challenge was 1:8~1:16.Histopathological and immunohisto-chemical tests showed that MEV genetic engineering subunit vaccine could well prevent the replication of virus in intestinal mucosal epithelial cells and the damage to intestinal epithelial cells.Therefore,the antibody titer was highest at 21 day-old after immunizing female mink,and the prepared vaccine could break through maternal antibody interference and produce high levels of antibodies when it immunized minks at about 50 d of age,and could resist the attack of mink enteritis virus virulent strain.     

荸荠茎腐病病原菌鉴定及生物学特性的研究

荸荠茎腐病是荸荠的一种真菌性病害。新月弯孢霉被证明为该病的病原菌。病菌生长发育的最适条件是：温度为２８－３３℃，酸碱度为ｐＨ６－８，相对湿度为８０％以上。     

新兴城市城区建设对周边水系生态基流的影响——以杨凌农业高新技术产业示范区为例

[目的]针对城市建设对周边水系河流生态特别是生态基流影响研究薄弱的问题,以陕西省杨凌示范区及城边水系为研究对象,分析新兴城市城区建设与周边水系生态基流内在联系,为流域生态用水规划和河流水资源合理配置提供科学依据。[方法]采用最枯月平均流量法计算河流生态基流量,以河流最枯月月均流量与城市建设用地面积间的关系确定保护河流生态功能的城市建设用地面积警戒值,并从输沙消污角度研究了城区建设对保障生态基流的影响。[结果]①杨凌城边的渭河、漆水河和小韦河需要保障的生态基流量分别约为6.0,0.2和0.1 m~3/s,宜作为杨凌示范区用水规划和3条河流水资源调配的依据;②小韦河最枯月月均流量与杨凌示范区城市建设用地面积之间的内在联系符合指数函数规律,保障小韦河生态基流的城市建设用地面积警戒值约为60 km~2;③小韦河水体总氮和总磷月均浓度总体超过Ⅴ类水质标准,小韦河冬、春两季高污的现状使其生态基流的保障问题更加严峻和迫切。[结论]杨凌示范区城市建设与保障城边河流生态基流特别是小韦河生态基流的关系密切,海绵型城市建设是今后新兴城市建设的重要发展方向。     

烟草RAPD反应体系的建立与优化研究

以烤烟品种为材料,研究了烟草RAPD分析过程中的影响因素,包括模板浓度、Mg2+、dNTP、引物、Taq 酶、循环次数、退火温度等,建立了适于烟草RAPD分析的PCR反应体系：即在25μl反应体系中,模板用量为40ng;引物浓度为0.4μM;Mg2+浓度为2.5mM;dNTP浓度为0.2mM;Taq DNA聚合酶用量为1U。扩增程序为94℃预变性5min;然后94℃变性1min,38℃复性1min,72℃延伸1.5min,39个循环;最后72℃延伸5min。     

模型定量评价技术研究--以东北地区马铃薯甲虫风险评估为例

本文以马铃薯甲虫为例,探索建立不同分析方法所预测结果之间的定量评估技术,并以此明确马铃薯甲虫在我国东北地区的适生范围和定殖风险。研究采用统一的环境数据、生物数据,分别利用 GAM、MaxEnt、GARP 3种模型对马铃薯甲虫在我国东北地区潜在分布风险进行了预测,并对预测结果进行了统计分析。GAM 模型在本文设定数据条件下,表现出最好的预测正确性,其最优模型AUC 达到0.87。由本研究过程可见,模型的选择首先应当在技术条件允许的情况下尽可能多的对模型在不同数据条件下表现出的性能进行考查,并对采用的分析结果保持足够的谨慎,在认识到模型可能存在局限的情况下有限度的接受和使用预测结果。     

高硒日粮对本种三黄雏鸡的毒性试验

将１２日龄健康三黄雏鸡１２０羽随机分成１５组。对照组饲喂大江商品小肉鸡饲料，其它各组在饲喂上述饲料的基础上分别添加０．２、０．４、０．８、１．６、３．２、６．４、９．６、１４．４、２１．６、３２．４、４８．６、７２．９、１０９．３５、１６４、０２５ｍｇ／ｋｇ浓度的亚硒酸钠性硒，试验持续２８天。试验结果表明，在饲料中不影响雏鸡增重的含硒量为９．６ｍｇ／ｋｇ左右。饲料中含硒量达１４．４ｍｇ／ｋｇ以上时，雏鸡日增重较对照组极显著降低，料重比较对照组显著升高。并随剂量增大雏鸡出现死亡的时间提前，死亡率增加。邹鸡的血硒随饲料中含硒量增加而呈指数曲线上升，曲线方程为。     

山西水土流失治理中的水资源调控途径

分析了山西水土流失及其引发的农业水资源利用问题。结合水资源的特点，探讨了在水土流失治理中的水资源调控途径，主要包括：推行水资源需求管理及节水型旱作农业、实施旱作农业调水调控技术、小流域治理的工程措施等。     

Integrating rainwater harvesting with supplemental irrigation into rain-fed spring wheat farming

A field experiment was conducted at the Haiyuan Experimental Station (36°34′N, 105°39′E), in a semiarid region of China, from 2000 to 2003 for rain-fed spring wheat (Triticum aestivum) production to maximize the utilization of low rainfall. This paper reports the two field cultivations of rainwater harvesting with a sowing in the furrow between film-covered ridges (SFFCR), and with a sowing in the holes on film-covered ridges (SHFCR). At the same time, the periods and indices of supplemental irrigation during the whole growth stage of rain-fed spring wheat were also studied. The periods of supplemental irrigation included the three-leaf stage (irrigated once), the elongation stage to flowering stage (irrigated twice), and the flowering stage to filling stage (irrigated once). The indices of supplemental irrigation during the whole growth stage of rain-fed spring wheat must reach over 59 and 40 mm in order to realize the 2250 and 2000 kg ha⁻¹ yield, respectively. This research also presented such a concept of efficient water saving supplemental irrigation, which was considered as a new index of water saving irrigation. The experimental result showed that the efficiency of water saving supplemental irrigation of field cultivation with SFFCR was 5.5–5.8%, and with SHFCR was 9.4–9.6%. The efficiency of water saving supplemental irrigation of field cultivation with SHFCR was improved by 40.4% in comparison with SFFCR. Consequently, in this region, the integration of rainwater harvesting and supplemental irrigation can play a crucial role in the improvement of rain-fed spring wheat yields and water use.     

母株年龄和插穗基部切削方式对日本落叶松生根的影响*

在无激素处理的条件下，１．５年生幼龄母株的插穗易于生根，平均生根率达９６．０％以上，且发根最大，偏根率低；４．５年生时，插穗生根率极显著低于１．５年生母株，而与８．５年生母株无显著差异；１２．５年生母株插穗生根率又极显著低于８．５年生母株。母株年龄与插穗生根率和偏根率分别呈显著的负相关（ｒ＝－０．９６５２）和极显著正相关（ｒ＝０．９９９３），但与生根量和平均最长根长度无显著相关。插穗基部切削方式不