关于加速雅安奶业产业化进程的思考与对策

通过招商引资壮大雅安市现有乳品加工企业的能力与水平,带动奶业基地发展;建立奶业协会,破除当前条块分割、体制不顺等问题,提高农民养奶牛奶羊的组织化程度;建设奶业高种园区,提高科技贡献率,充分利用雅安发展奶业得天独厚的优越条件及大好机遇,超常规跨越式发展,使雅安市成为四川奶业强市.     

家蚕蛾黄翅的遗传分析与黄血基因的多效作用

在保存家蚕突变基因资源过程中调查发现：黄血蚕蛾翅在羽化之初呈鲜黄色,白血蚕均不然。通过与白血蚕（非黄翅）和黄血抑制基因（I）进行杂交试验,分析黄翅的遗传规律,结合普查家蚕突变系统蛾翅色性状,证明黄翅性状与幼虫黄脚一样,为黄血基因支配。进而记录了因黄血基因的多效作用在卵、幼虫、茧、成虫各阶段表现的形态特征。     

The Effects of Agricultural Practices on Carabidae in Temperate Agroecosystems

Ground beetles (Coleoptera, Carabidae) occur in all temperate agroecosystems, and have been implicated as predators of many pests, including aphids, lepidopterous larvae, and slugs. Most are polyphagous, and some are primarily spermophagous. The species assemblage present in any particular crop is determined by multiple factors, but usually comprises a limited number of abundantly active species, which may be common to many crop types. Abiotic soil factors, especially soil type and moisture status are important in determining the species present. Crop type affects the carabid assemblage indirectly through cultivation practices and microclimatic changes. Any soil cultivation affects the carabid assemblage, but studies comparing ploughing with reduced tillage have shown varying results, according to local conditions. Pesticides, especially insecticides have a localised and short-term effect, as many carabids rapidly re-invade sprayed crops. The long-term effect of pesticide usage at a landscape scale is, however, more difficult to predict, and may have contributed to the observed decline in carabid diversity in the wider countryside. Whilst fertiliser application is generally beneficial to carabids, comparisons of conventional and organic farming systems suggest that localised short-term variations in species abundances are more important than the overall farming system used. Non-crop habitats are very important to Carabidae, as many use adjacent hedges and field margins for shelter, breeding or dispersal. But other features such as roads may act as barriers to dispersal. It is concluded that further measures need to be taken if Carabidae are to realise their potential in integrated pest management systems.     

三江源区高寒草甸草场放牧牦牛采食量的测定

试验选用约2．5岁公牦牛8头，在三江源地区玉树县的高寒草甸草场，应用4N盐酸不溶灰分法（4N—AIA）和木质素标记物法测定了不同物候期（青草期和枯黄期）放牧牦牛日采食量及牧草营养成分的消化率。结果表明：2．5岁牦牛在青草期、枯黄期的100kg体重日采食量分别为3．69kg和2．96kg，差异极显著（P〈0.01）；其不同物候期的千物质消化率分别为65．70％、61．72％（P〉0．05），粗蛋白的消化率为62．25％、39．00％（P〈0．01），粗脂肪为49．36％、58．18％（P〈0．05），ADF的消化率为57．88％、62．67％（P〉0．05），NDF的消化率为69．09％、79．38％（P＜0．01）。     

奶牛酒精阳性乳与自由基代谢及乳腺损伤关系的研究

对酒精阳性乳患牛衄清与乳清中的抗氧化指标进行了检测，从自由基代谢与损伤的角度探讨了酒精阳性乳的发病机理；同时检测了阳性牛血清与全乳中微量元素Zn、Cu、Mn、Fe的含量，分析了微量元素含量变化与自由基代谢的关系。试验结果显示阳性牛体内发生了过度的过氧化反应，机体总抗氧化能力下降，机体的扰氧化系统已不能有效地清除活性氧及代谢产物，过多的氧自由基可能对乳腺上皮分泌细胞细胞膜造成微损伤，从而引起乳腺细胞分泌异常乳。     

黄芪多糖对人工感染IBDV雏鸡红细胞免疫功能的影响

将由未免疫接种腔上囊病疫苗鸡的种蛋孵化而来的160只1日龄海兰白雏鸡随机分为A、B、C和D共4组。A组为对照组，B、C和D组于26日龄时按每只0．3mL的剂量用IBDV攻毒。A、B组未用黄芪多糖（APS）处理，C、D组从攻毒当日起连续胸肌注射APS6d，剂量分别为每只鸡5mg和10mg。分别在21、29、32、35、38日龄时心脏采血1～3mL，测定E—C3bRR、E—ICRR、ERER和ERIR。结果显示，雏鸡感染IBDV后可使E-C3bRR和ERER显著降低（P〈0．01）；APS处理组E-C3bRR、E-ICRR、ERER均高于A、B组（P〈0．01），其中D组最高，而ERIR则与A组相似。证实，雏鸡感染IBDV后红细胞免疫功能低下，而APS可显著提高其红细胞免疫功能。     

Evolution of farm management, nitrogen efficiency and economic performance on Dutch dairy farms reducing external inputs

The implementation of the statutory Mineral Accounting System (MINAS) in the Netherlands in the period 1998–2003 required large reductions in nutrient inputs of dairy farms. Patterns in farm management adjustments throughout 6 years and their effectiveness in terms of nitrogen use efficiency (NUE) and economic performance were evaluated for 45 commercial farms participating in a regional nutrient management project.

Six groups of farms were identified that differed in initial NUE and the change therein. Three groups of farms that were able to rapidly reduce fertilizer N input and establish a consistent farm management strategy were most successful in improving NUE. These farms had a higher gross margin per 100 kg milk than farms without a consistent strategy. The three effective strategies were primarily characterized by (i) continuous, gradual adjustment of the integrated farm management combined with a slight reduction in milk production per ha (re-balancing) versus increasing productivity per animal, thereby reducing maintenance N requirements, while (ii) maintaining or (iii) increasing the production intensity per ha. It was concluded that different approaches to improve NUE can be successful, also in economic terms, although a direct relationship between NUE and gross margin was not observed. The probably implicit choice for adoption of a strategy may be governed by farm endowment and the farmer's skills and objectives.     

The use of even-chain alkanes sprayed onto herbage as rate of passage markers in goats

An experiment was conducted with Saanen goats fed fresh grass ad libitum to compare ⁵¹Cr-mordanted fibre and even-chain alkanes sprayed onto either grass leaves or stems to estimate faecal output, total mean retention time (TMRT) and parameters obtained from faecal marker concentration curves, such as k₁ (slow rate of passage), k₂ (fast rate of passage) and transit time (TT). ⁵¹Cr-mordanted grass showed the lowest fractional rates of passage (k₁ and k₂) and hence the largest value of TMRT. There were not significant (P > 0.05) differences between even-chain alkanes sprayed onto leaves or stems for k₂, TT and TMRT, but k₁ estimates were higher (P < 0.05) for stems than for sprayed leaves. Despite the marker used, TMRT values were negatively correlated with the level of dry matter intake (r = − 0.81, − 0.80 and − 0.80 for ⁵¹Cr-mordanted fibre and even-chain alkanes adsorbed onto leaves or stems, respectively). Average faecal outputs estimated from faecal concentrations of ⁵¹Cr-mordanted fibre and even-chain alkanes were not different from the actual outputs but there were differences between markers in the accuracy of estimation. The highest mean square prediction error (MSPE) and the poorest correlation between observed and estimated faecal output values corresponded to even-chain alkanes adsorbed onto stems. Values estimated using ⁵¹Cr-mordanted fibre and even-chain alkanes adsorbed onto leaves were significantly correlated with faecal outputs (r = 0.94 and r = 0.92, respectively), with MSPE being greater for the latter marker.     

Longevity of Swiss Brown cattle in different housing systems in Switzerland

A Weibull mixed survival model was used to study the effect of a change in the housing system on length of productive life (LPL) in dairy cows. The data set included records on 71,469 Swiss Brown cows in 1674 farms in eastern and central Switzerland. About 36% of the records were right-censored. The observation period lasted from January 1, 1988 to May 1, 2001. During this period, 517 farms changed their housing conditions from a tie-stall barn to a loose housing system. Besides a random time-dependent effect of herd–year–season, the model included fixed effects of housing system, lactation number and stage of lactation, within herd and parity production level (all time-dependent), and age at first calving (time-independent). All effects had a significant effect on LPL at a level of p < 0.001. Cows in loose housing systems showed the lowest risk ratios of being culled (0.93) compared to the reference system tie-stall barn (1.00). The highest relative culling rate (1.09) was observed within the changing period from tie-stall barn to loose housing system. Within the first three lactations, the relative culling risk increased stepwise with lactation stage. The hazard slightly increased from first until lactation number 8 and higher. The relative culling rates were highest (2.22) for cows yielding less than 90% compared to herd-mates of the same lactation number, whereas the lowest risk ratios were estimated for animals yielding more than 110% compared to their reference group (0.64). When heifers were older than 3 years at first calving, there was a tendency towards a higher relative culling risk (1.06).     

我国农业保险发展经营模式研究

我国农业灾害损失相当严重，农业保险是有效分散农业风险促进农业和农村经济发展的重要手段，针对我国实际国情，选择合适的农业保险发展模式十分重要。本文在分析了国内外各种农业保险发展模式的基础上，提出了我国农业保险发展模式。并对其进行了深入分析。