不同性别生长猪所需最佳苏氨酸与赖氨酸比率

本研究通过调查苏氨酸与赖氨酸的比率对猪生长性能、表观可消化能和血液尿素氮 (BUN)浓度的影响 , 估测生长阉公猪和小母猪所需最佳苏氨酸与赖氨酸的比率 . 试验采用 150头杂交猪 (长白×约克夏×杜洛克 , 平均体重为 16.75± 0.45 , 其中阉公猪 75头 , 小母猪 75头 ), 按 2× 3析因设计 , 随机分成 6个处理 阉公猪日粮含赖氨酸 1.12% , 按苏氨酸与赖氨 酸比率为 50% 、 60% 和 70% 分成 3个处理 小母猪日粮含赖氨酸 1.33% , 按苏氨酸与赖氨酸比 率为 50% 、 60% 和 70% 分成 3个处理 . 经整个试验期 (体重从 16至 56 ). 在平均日增重、平均 日采食量和饲料转化率方面 , 动物性别和苏氨酸与赖氨酸比率之间无相互影响 . 在生长性能 方面 , 有明显的性别影响 与小母猪相比 , 阉公猪表现出较好的生长性能 , 消耗较多的饲料 (P< 0.01)以及生长的较快 (P< 0.01). 随着苏氨酸与赖氨酸比率的增大 , 阉公猪的 ADG和 FCR有增加的倾向 , 但差异不显著 . 在除粗灰分 (CA)外的可消化性养分方面 , 动物性别和苏氨 酸与赖氨酸比率之间无相互影响 . 在性别之间 , 除小母猪对钙具有较高的可消化性 (P< 0.01)外 , 可消化性养分没有存在的差异 . 而日粮苏氨酸与赖氨酸比率对可消化性养分无影响 . 可消化性必需氨基酸 (EEA)、非必需氨基酸 (NEAA)和总氨基酸 (TTA)的平均值没有受到性别 和苏氨酸与赖氨酸比率的影响 . 没有发现性别和日粮中苏氨酸与赖氨酸比率相互影响的证据 . 在性别之间 , 小母猪的总 BUN浓度比阉公猪低 (P< 0.05). 可以得出结论 " 阉公猪日粮 (赖氨 酸水平为 1.12% )中 , 苏氨酸与赖氨酸比率为 70% , 小母猪日粮 (赖氨酸水平为 1.33% )中 , 苏 氨酸与赖氨酸比率为 60% , 较其它比率的苏氨酸与赖氨酸 , 分别获得较好的生长性能、养分 利用和较低的 BUN浓度 .     

Control of seed-borne Sclerotinia sclerotiorum by fungicidal treatment of sunflower seed

Treatment of sunflower seeds with benomyl, vinclozolin, iprodione or procymidone virtually eliminated seed-borne Sclerotinia sclerotiorum. Applications of fungicides increased the number of surviving seedlings when seeds were sown in vermiculite or in steam-sterilized soil. With the exception of benomyl, fungicides were significantly more effective when applied in acetone solutions than when 100 g a.i./100 kg of seed was applied as conventional dry dressings. There was no difference in effectiveness between the two application methods when the dry dressings were applied at 200 g a.i/100 kg of seed. The acetone infusion method had no deleterious effects on germination of disease-free seed nor on seedling vigour. For a comparable level of control, less fungicide was needed in the infusion treatment than in the dust treatment. If fungicidal treatment of sunflower seeds is used routinely then the introduction of S. sclerotiorum into uninfested land could be controlled.     

Isolation and partial characterization of thermostable isoperoxidases from potato (Solanum tuberosum L.) tuber sprouts

Peroxidases (POD; EC 1.11.1.7) can cross-link cell wall polymers and may have an impact on the final textural quality of potato tubers. Because heat treatments are important during processing, the thermal properties of isoPODs from soluble and ionically and covalently bound fractions were studied from both potato tubers and sprouts. For both tissues, the ionically bound fraction was the most thermostable; approximately 20% of POD activity remained after a heat treatment of 10 min at 90 degrees C (for sprouts). The temperature profile of the ionically bound sprout fraction appeared to be nonlinear and suggested the presence of a very thermostable POD, which still showed activity after a heat treatment at 100 degrees C. Visualization by using isoelectric focusing confirmed the occurrence of a thermostable isoPOD with an IEP of 9.5, which displayed regeneration of activity after heat inactivation. This cationic POD was further purified by chromatography techniques, and by SDS-PAGE its molecular mass was estimated at 38 kDa.     

Breeding for resistance: breeding for Plum pox virus resistant plums (Prunus domestica L.) in Germany

In German plum breeding programmes new varieties tolerant to Plum pox virus (PPV) were initially obtained by selecting hybrids originating from crossings between tolerant old varieties while, later on, sharka tolerant varieties bred in Čačak, Serbia were used as crossing partners. Varieties released from these programmes replaced the sensitive ones in all sharka infected regions in Germany. While all the new tolerant varieties can be infected by the virus, PPV symptoms on the fruits are acceptable. However, environmental factors can weaken the plant, causing them to suffer more from PPV infections and to display worse symptoms on fruits, as did occur during some recent very dry and warm years. A breeding programme at the University of Hohenheim is tackling this problem with genotypes that show a hypersensitive response after infection. These genotypes are completely field resistant to PPV, remaining virus free in the field since they cannot be infected via aphid transmission. They are able to isolate the virus after infection. The first hypersensitive variety was 'Jojo'. Many seedlings originating from crossings with at least one hypersensitive parent are under evaluation. Since the inheritance of the trait 'hypersensitivity against PPV' is very good, combining hypersensitivity with excellent fruit quality and good cropping capacity will be possible soon. In 2005, a breeding programme for hypersensitive Prunus genotypes began at the Technical University of Munich.