饲草青贮添加剂研究进展

为了提高饲草青贮发酵效率,改善发酵品质,调制青贮时常使用添加剂,文章综述了近年来青贮添加剂的研究进展。根据其作用机制青贮添加剂可以分为4类,分别是发酵促进型添加剂、发酵抑制型添加剂、好氧性变质抑制剂、营养型添加剂等。乳酸菌因具有促进有氧稳定性、抑制二次发酵、产生抗菌物质、抑制有害微生物等特点已广为应用。纤维素酶制剂添加效果主要受酶本身的特性、青贮原料的特性及青贮时的管理等因素影响,其添加效果尚有待于进一步研究。绿汁发酵液是一种新型的青贮添加剂,具有取材方便、制作简单的特点,可明显改善青贮原料的发酵品质。未来饲草青贮添加剂应用应全面考虑环境要素,加强酶的活性研究,注重多学科综合分析,用纤维素酶与乳酸菌、绿汁发酵液、蔗糖、甲酸等常规青贮添加剂进行复合青贮可能取得进步。     

中草药饲料添加剂在生产上的应用

综述了中草药饲料添加剂的特点、种类、应用现状和存在的问题,并对今后的发展趋势作做了展望。     

中草药饲料添加剂饲喂贵州黄羽肉鸡效果试验

将1000羽贵州黄羽肉鸡根据单因子随机分组设计分为5组,每组200只,进行饲养试验,测试中草药饲料添加剂对贵州黄羽肉鸡生长性能及肉品品质的影响。试验Ⅰ组为对照组,饲喂基础日粮;试验Ⅱ组为基础日粮＋0．2％中草药添加剂;试验Ⅲ组为基础日粮＋0．4％中草药添加剂;试验Ⅳ组为基础日粮＋0．6％中草药添加剂;试验Ⅴ组为基础日粮＋0．8％中草药添加剂。试验结果：Ⅱ、Ⅲ、Ⅳ和Ⅴ组13增重分别比Ⅰ组提高0．14％、11．87％、11．54％和5．84％。肉品质测定试验结果：添加0．6％的中草药饲料添加剂的贵州黄羽肉鸡肌肉中的氨基酸组成较好。     

贝尔饲料精对家蚕叶丝转化率的影响

贝尔饲料精是一种主要由多种氨基酸、葡萄糖及少量微量元素等组成的营养复合物。在缺乏桑叶或桑叶质量较差时，用它作蚕儿的添加剂，可以补充蚕儿营养，保证丝物质合成的顺利进行。当桑叶充足叶质良好时，用贝尔饲料精作添加剂，对茧丝质影响较大。本试验用２５倍液、３３倍液、５０倍液添食，结果：提高了养蚕各项经济指标，尤其以３３倍液更增加茧丝长和解舒丝长，提高叶丝转化效率。     

Habitat associations of Atlantic herring in the Shetland area: influence of spatial scale and geographic segmentation

This study considers the habitat associations of a pelagic species with a range of biotic and abiotic factors at three different spatial scales. Generalized additive models (GAM) are used to analyse trends in the distributional abundance of Atlantic herring ( Clupea harengus ) in relation to thermocline and water depth, seabed roughness and hardness, sea surface salinity and temperature, zooplankton abundance and spatial location. Two geographical segments of the population, those east and west of the Shetland Islands (northern North Sea, ICES Div IVa), are examined. The differences in the ecological preferences of the species in these two distinct geographical areas are elucidated and the degree that these environmental relationships might be modulated by the change of support of the data is also considered. Part of the observed variability of the pre-spawning distribution of herring was explained by different parameters in these two regions. Notwithstanding this, key determinants of the species' spatial aggregation in both areas were zooplankton abundance and the nature of the seabed substrate. The relative importance of the variables examined did not change significantly at different spatial scales of the observation window. The diverse significance of various environmental factors on herring distribution was attributed mainly to the interaction of species' dynamics with the different characteristics of the ecosystem, east and west of the Shetland Islands. Results suggest that the current 2.5 nautical miles as elementary sampling distance unit (ESDU) is a reasonable sampling scheme that combines the need to reduce the data volume while maintaining spatial resolution to distinguish the species/environment relationships.     

Additive effects of copper and zinc on cadmium toxicity on phosphatase activities and ATP content of soil as estimated by the ecological dose (ED50)

The ecological dose (ED₅₀) of Cd on alkaline and acid phosphatase activity and the ATP content of three contrasting forest soils was measured with or without Cu and Zn to assess the additive toxic effects of these two metals. Soils polluted with Cu and/or Zn were treated with increasing Cd concentrations to give the following metal combinations: Cd, Cd+Cu, Cd+Zn and Cd+Cu+Zn. Alkaline and acid phosphatase activities and ATP content of the three soils were analysed 4 h, 7 and 28 days after the metal additions. The ED₅₀ values were obtained by interpolating the enzyme activities or ATP data with a kinetic model and the goodness of fit was satisfactory.Generally, the ED₅₀ values of both acid and alkaline phosphatase activities for Cd were lower (higher toxicity) with than without Cu and Zn and the effect of Cu and Zn was particularly adverse when these two metals were both added to soils. The alkaline phosphatase was more sensitive in the acid and neutral soil whereas the acid phosphatase was more sensitive in the alkaline soil. Both phosphatase activities and the ATP content were more sensitive in the sandy than in the finer textured soils. The ATP content was less sensitive to the additive effects. Increasing toxicity was observed during the incubation.Analysis of 1 M NH₄NO₃-extractable Cd, Cu and Zn revealed that Cd competed with Zn for the adsorption sites but not with Cu. However, the lower ED₅₀ values for Cd of the two phosphatase activities and of the ATP content in the presence of heavy metal combinations could be not explained by the heavy metal solubility data. It is concluded that the ED₅₀ may be a sensitive tool for assessing additve toxic effects to soil biochemical parameters.     

不同添加剂对高水分全株玉米青贮饲料发酵品质和细菌群落的影响

为探讨不同添加剂对高水分全株玉米(Zea mays L.)青贮饲料发酵品质和细菌群落的影响,本试验以乳熟期的全株玉米为原料,设置对照、添加苯甲酸钠和植物乳杆菌3个处理,青贮60 d后,测定其营养成分、发酵指标和细菌群落组成。结果表明:植物乳杆菌和苯甲酸钠均能使高水分全株玉米青贮饲料的细菌群落发生一定变化,并以乳杆菌属细菌为优势菌群(>70%);2种添加剂均未降低高水分全株玉米青贮饲料的细菌多样性;与对照相比,用植物乳杆菌处理高水分全株玉米青贮后,其氨态氮含量呈显著增加的趋势(P<0.05),用苯甲酸钠处理的高水分全株玉米青贮后,pH值升高(P<0.05),有机酸含量降低。因此,2种添加剂对高水分全株玉米青贮饲料发酵品质的改善效果不佳。     

Microbial community response to soil solarization in Nepal's rice-wheat cropping system

The Indo-Gangetic Plains of South Asia support 13.5 million hectares of rice-wheat cropping systems, which currently feed over one billion people. Intensified agriculture has resulted in a more than two-fold increase in rice and wheat yields since the 1970s; however, this continuous cropping has also exacerbated weed, pest and disease problems. Soil solarization is an accessible, low-risk management practice for small-holder farmers that has ameliorated these problems in some settings and has the potential to dramatically improve yields. Field trials were conducted at two sites in Nepal to test whether soil solarization: (i) had a lasting effect on soil bacterial, fungal and nematode communities; (ii) altered the rhizosphere communities of rice nursery seedlings and (iii) improved crop growth and yield in the rice-wheat cropping system. Rice seedlings were grown in nursery plots that were solarized for 28 days or left untreated and were transplanted to field plots that were also either solarized for 28 days or not in a randomized complete block design with four replications. Rice was grown to maturity and harvested, followed by a complete wheat cropping cycle. Solarization of main field plots increased counts of fungal propagules and decreased root galling and nematode counts and decreased weed biomass. Terminal restriction fragment length polymorphism (T-RFLP) analyses of extracted soil DNA revealed significant shifts in fungal community composition following soil solarization, which was sustained throughout the entire rice cropping cycle at both field sites. The bacterial community composition was similarly affected, but at only one of the two sites. Despite the observed changes in soil microbial community composition over more than one cropping period, solarization had no impact on crop productivity at either site. Nevertheless, such changes in soil microbial communities in response to solarization may be responsible for increased yields observed at other sites with greater pathogen pressure. This practice has shown promising results in many farmers’ fields in South Asia, but further elucidation of the mechanisms by which solarization increases productivity is needed.     

冬小麦一些数量性状的加性相关和显性相关分析

用不完全双列杂产方法和加显性遗传模型，对冬小麦一些数量性状进行了多种相关分析。结果表明，所研究的株高有关性状间的多种相关几乎均达极显著水平，且加性相关更为重要；单株穗数、主茎穗长、结实小穗数、主穗粒重间的加性相关达显著或极显著水平（单株穗数与主穗粒重除外）；单株粒重与其它性状间的加性相关均不显著，而显性相关大多达显著或极显著水平。     

药物添加剂——“肥宝”促进幼兔生长试验

以当地产的中草药为主要成分，研制出促进肉兔生长的添加剂——肥宝，经试验表明，对幼兔生长有明显的促进作用，饲料中添加３％“肥宝”，可使幼兔增重速度提高３１．８％，好于黄腐酸、兔乐１号、复合酶制剂等添加剂对幼兔的增重效果，经济效益高，在当地具有广阔的应用前景