沙区五种珍稀濒危植物水分生理指标测定及分析

本文在测定沙区５种珍稀濒危植物的水分生理指标的基础上，分析了其抗旱性，意在探讨适应干旱环境的特性。研究结果表明：矮沙冬青保水能力与吸水能力强，对干燥炎热的环境有很强的适应性；银沙槐蒸腾强度大，失水快，但吸水力强，补偿水分快；裸果木通过强的保水力适应干旱；绵刺以强的吸水力和抗脱水力适应环境；准噶尔无叶豆以体内水分自我调节作用适应大气干旱。     

A Comparison of Techniques for Preparing Somatic Chromosomes in Ribes Species

Ribes plants,like most of other fruit trees ,are characterized by their large number but small size of somatic chromosomes.In the light of these spccial characteristies,we have examined several factorial combinations of material,pretreatment,slide preparing method and stain to identify the most promising techique for studying the chromosomes and further analyzing the karyotypes and chromosome banding of Ribes plants.The resuts indicated that the combination of root tip with pretreatment of 2m molL^-1 8-hydroxyquinoline plus 0.05% colchicine or 0.3% balm for 3-5 hours at 14℃,pre-hypotonic treatment of 0.07mol L^-1 KCl for 30min,fixation in Carnoy‘s fluid,hydrolysis in 5% cellulase and 5% pectinase mixture for 4-5 hours at 25℃,post-hypotoic treatment in distilled water for half an hour and staining in Giemsa Could make the chromosome preparation superior to other treatment combinations.     

青壳蛋遗传规律初探

为了研究青壳蛋遗传规律,我们对青壳蛋鸡进行了四个世代的选育。二、三、四世代产青壳蛋及非青壳蛋母鸡个数分别为205,22;258,17;635,15;与计算出的理论数据206.21;260,15;636,14经卡方检验差异不显著。对一世代、三世代进行测交,其后代产青壳蛋与非青壳蛋母鸡个数分剐为613,463;706,236;与通过一世代、三世代的显性基因频率与隐性基因频率计算出的理论数据600,467;707,235经卡方检验差异不显著。选择加快了群体基因频率的改变,青壳蛋性状确为由一对主效基因控制的完全显性遗传性状。     

影响绵羊冻胚移植妊娠率的因素分析

本研究对胚胎质量、胚胎移植数量、胚胎发育阶段、冷冻方法、移植方法及饲养管理水平等因素对移植产羔率的影响进行研究,以提高绵羊胚胎移植效率。结果表明:采用1.5mol/L乙二醇做冷冻保护剂对胚胎进行常规冷冻,冻前A级胚胎冷冻/解冻后可用胚率、存活率、降级率均高于B级,差异极显著(P<0.01)。移植1枚冷冻解冻后A级、B级或2枚(A+B)胚胎的受体移植产羔率分别为44.48%、46.84%和44.81%。经χ2检验分析,三者之间无显著差异(P>0.05)。移植双胚的受体双羔率为22(%53/241),以胚胎为单位计算,产羔率仅为33.40%。A级囊胚和桑椹胚的产羔率之间无显著差异(P>0.05)。1.5 mol/L乙二醇常规冷冻保存的体内胚胎移植产羔率高于EFS40玻璃化冷冻保存,但经统计学分析,二者无显著差异(P>0.05)。子宫手术移植和腹腔内窥镜法子宫移植之间产羔率不具统计学差异(P>0.05)。在牧场条件下大规模移植的平均产羔率为43.95%,范围在20%￣70%之间,受体饲养管理水平对绵羊移植产羔率有较大影响。     

鸡霍乱口服弱毒疫苗的研究

用经过选择的禽多杀巴氏杆菌自然弱毒菌株Ｒ１－２３菌株制成的鸡霍乱固体培养口服弱毒疫苗，其安全剂量接近于２００个免疫剂量。该口服苗两次饮水免疫的最适总剂量为每羽５０亿个活菌，最佳间隔时间为４８小时。免疫鸡第二次饮苗后第３天即可产生较好的免疫保护率（７／８）。免疫鸡对异型强毒株Ｐ１０５９（８∶Ａ）、Ｐ２７２３（９∶Ａ）和同型强毒株Ｃ４８－１（５∶Ａ）滴鼻攻击的近期保护率平均为５／１０、６／１０和９／１０。６个月免疫期的平均保护率为７６．７０％（４６／６０），一万多羽鸡田间试验结果表明，免疫后２个月的平均保护率为９３．１０％（２７／２９），６个月的平均保护率为７３．５０％（２５／３４），除对产蛋率有轻度影响（下降１．２７％）外，无其它不良反应。野外大面积使用结果表明，该口服苗不但性能稳定，免疫原性优良，而且安全可靠，适用于鸡口服免疫。     

河北省承德地区防护林体系林种结构的最佳模式

本文用线性规划方法,把以防护效益为主并满足社会需求作为约束条件,使防护林工程的费用最小作为目标,计算出了河北省承德地区防护林体系林种结构的61个方案。对不同情况,如资金不足、取得较好的经济效益、解决木材供需矛盾以及其它条件的变化等等,可以从61个方案中选出一个最佳方案。     

应用生物素标记的NDV－cDNA探针检测感染尿囊液中NDV－RNA的初步研究

本文应用聚合酶链反应（ＰＣＲ）技术从构建的新城疫病毒（ＮＤＶ）ｃＤＮＡ文库中扩增含编码Ｆ糖蛋白前体──Ｆｏ酶切位点序列的３５９ｂｐ的Ｆ蛋白基因ｃＤＮＡ片段。将此３５９ｂｐｃＤＮＡ片段经光敏生物素标记后,即成ＮＤＶ－ｃＤＮＡ探针。该探针能特异性地从感染的尿囊液中检测出ＮＤＶ强毒株和疫苗毒株的基因组ＲＮＡ,而不与ＩＢＤｖ－ｄｓＲＮＡ、ＡＩＢｖ－ｓｓＲＮＡ、ＥＤＳ７６－ｄｓＤＮＡ、ＭＤＶ－ｄｓＤＮＡ,ＦＰＶ－ｄｓＲＮＡ及ＡＩＬＶ－ｄｓＤＮＡ发生交叉杂交反应。试验结果表明：尽管该探钎含有编码Ｆｏ蛋白酶切位点序列的碱基顺序,但它还是不能把ＮＤＶ的强、弱毒株区分开。这说明ＮＤＶ强、弱毒株比区域内的碱基存在着相当大的同源性。不过,此探针对ＮＤＶ来说具有特异性,这就为ＮＤＶ的诊断技术开创了基因水平检测的新途径。     

Correlated responses from selection for income minus food cost in pullets on traits in older hens

1. After 5 generations of selection on income minus food cost between 21 and 40 weeks of age (SECR), a correlated genetic improvement of 14.5% and 16.3% of the base population mean could be observed for income minus food cost between 41 and 60 weeks (IF60) in two lines of laying hens. The total responses up to 60 weeks amounted to 17.2% and 17.3% of the base population mean. A heritability of 0.30 for IF60 and a genetic correlation of 0.61 between SECR and IF60 were estimated.

2. The correlated relative genetic responses for 5 traits of the period between 41 and 60 weeks of age for the two lines were: 4.3% and 5.2% in egg number, 5.8% and 7.4% in egg weight, 8.4% and 10.8% in egg mass, ‐2.7% and ‐0.6% in body weight at 60 weeks, and ‐5.2% and ‐6.3% in food efficiency.

3. The estimated heritabilities of these 5 traits from the whole data set were 0.36, 0.75, 0.34, 0.71 and 0.17. The estimated genetic correlations between SECR and the same 5 traits were 0.30, 0.46, 0.61, ‐0.22 and ‐0.49.

4. A high genetic correlation of income minus food cost with egg weight and a low one with egg number were found in pullets, but the relationships were reversed in older hens.     

Effects of an induced pause in egg production and supplementation of the diet with iron on egg shell colour,quality and performance of brown egg layers

1. A pause in egg production was induced in brown‐egg laying hens, aged 68 weeks, by feeding them whole oats for 7 d. Subsequently, these hens, together with control groups, were given laying diets with either 400 or 600 mg/kg iron. The 200 mg/kg of supplemental iron was added in the form of either ferrous sulphate or iron proteinate (chelated iron).

2. The feeding of whole oats halted egg production in 5.7 ±0.22 d and the duration of the pause was 8.3 ±0.78 d.

3. The induction of a pause improved the subsequent rate of egg production, egg output, efficiency of food utilisation, albumen quality, egg specific gravity and shell colour. It also increased food intake and body weight gain but neither egg weight nor the rate of mortality were affected.

4. Neither supplementation of the diet with iron nor its source had any significant effect on laying performance, egg quality or shell colour.