Evaluation of smallholder pig production systems in North Vietnam: Pig production management and pig performances

This study investigated the productive adaptability of pig breeds under different smallholder production conditions in Vietnam, comparing an indigenous with a Vietnamese improved breed. Fieldwork was conducted in four villages with different remoteness in North Vietnam from 2001 to 2002, in 64 households keeping the improved Mong Cai or indigenous Ban as sow breeds and progeny for fattening. Four visits per farm yielded 234 structured interviews. Reproductive performances were derived from 135 litters. Individual weights of pigs (n = 755) were obtained. Data were analysed by regression, linear and generalised linear, especially loglinear models.

Two distinct pig production systems were identified, that differed in remoteness, market access, resource availability, distribution of pig breeds and pig production intensity. Higher performances of 1.4 and 1.5 litters year^− 1, 8.4 and 8.4 piglets weaned litter^− 1, 66.6 and 93.0 kg piglets weaned sow^− 1 year^− 1, and 136 and 177 g day^− 1 ADG were found in two villages near town with semi-intensive production conditions and a high rate of improved Mong Cai sows and MC and LW × MC offspring in the observed population. Lower performances of 1.1 and 1.1 litters year^− 1, 4.6 and 5.5 piglets weaned litter^− 1, 20.5 and 30.9 kg piglets weaned sow^− 1 year^− 1, and 66 and 85 g day^− 1 ADG were observed in parallel to higher incidences of indigenous Ban pigs away from town under extensive conditions. Total live weight offtake per household per year was higher near town and in one village distant to town. MC and LW × MC remained even under demand-driven conditions below the performance potential reported for improved genotypes. Under resource-driven conditions with a saving-oriented production pattern, the higher-yielding but more demanding Mong Cai might not be an efficient production alternative as a further performance reduction can be assumed. A considerable live weight output was observed under resource-driven conditions and with a higher percentage of crossbred LW × Ban offspring in the population, possibly representing a promising production alternative. Factors influencing the performance expression of pigs, and the suitability of different methods for the assessment of performance parameters on-farm are discussed.     

苏丹红和饲料着色剂的区别

本文主要从苏丹红和饲料着色剂的化学结构、作用机理及毒性等方面说明饲料着色剂与苏丹红的天壤之别。     

四氯联苯对鸡胚性腺原始生殖细胞的毒性影响

采用四氯联苯处理发育至Ⅹ期的白来航鸡种蛋,孵化5.5天后取出胚胎进行全固定,用石蜡切片和PAS染色(高碘酸希夫试剂)研究四氯联苯对鸡胚性腺原始生殖细胞(PGCs)的影响.结果表明,四氯联苯对发育至5.5日胚龄的鸡胚性腺PGCs数量和结构有明显影响,但雌二醇处理的5.5日胚龄鸡胚PGCs数量变化不显著,其结构无明显变化.表明四氯联苯对5.5日胚龄的鸡胚性腺PGCs的影响主要来自于其毒性作用.     

Antioxidant and stomatal responses of grapevine (Vitis vinifera L.) to boron toxicity

Although of considerable agronomic importance, our understanding of B toxicity mechanism in plants is still not completely understood, and remains an open question. Therefore, we investigated the effect of increasing levels of B (0, 10, 20 and 30 mg kg⁻¹) on the growth, boron (B) concentrations, stomatal resistance, lipid peroxidation (MDA), membrane permeability (MP), lypoxygenase activity (LOX), proline (PRO) and H₂O₂ accumulation, and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) of grapevine (Vitis vinifera L. cv. Kalecik Karasi) grafted on 5BB rootstock (V. berlandieri × V. riparia) was investigated. Applied toxic levels of B significantly reduced leaf and root growth and increased the B concentration of the leaf, and stem, bark and root of rootstock. In the all B levels leaf tissues of grapevine accumulated more B than that of the other plant parts. In order to restrict excessive uptake of B, stomatal resistance of the leaves increased especially at high B treatments (20 and 30 mg kg⁻¹). The concentrations of H₂O₂, MDA and membrane permeability were increased as the result of B toxicity while proline and the activity of lypoxygenase were decreased. Compared with control plants, the activities of SOD and CAT were increased by B treatments while the activity of APX was decreased. To our knowledge, this is the first report that B toxicity elevated the antioxidant enzymes to protect the membrane functions from reactive oxygen species (ROS) injury in grapevine and it was hoped that this study would provide a basis for developing strategies for reducing the risks associated with B toxicity.     

纳他霉素防治苹果贮运期病害的初步研究

采用生长速率法测定了纳他霉素对苹果轮纹病菌、苹果黑星病菌、苹果黑斑病菌、苹果腐烂病菌的室内毒力,结果表明,该制剂对各病菌的抑制有效中浓度EC50分别为18.44、49.43、32.08、29.87μg/mL,并用病原菌感染方法测定了制剂对贮运期苹果的实物防治效果。纳他霉素浓度为200μg/mL的制剂各处理组在10d、14d、18d的防效分别达到52.91%、55.02%、54.12%,显著高于多菌灵对照的防效。     

动物专用头孢喹诺的研究进展

头孢喹诺是动物专用的第4代头孢菌素类抗生素,具有广泛的抗菌和强大的杀菌作用。其抗菌活性极强,对临床分离的各种革兰氏阳性菌、革兰氏阴性菌的MIC50、MIC90值均较小;其药动学特点优良,吸收快,达峰时间短,生物利用度较高,药时曲线下面积较大,表现分布容积也很大;头孢喹诺毒性低,在动物的可食用组织中残留较少,安全性较高。国外已将该药应用于猪、牛的呼吸系统感染及牛乳房炎的治疗。为指导头孢喹诺在我国兽医临床上的合理应用,现对其抗菌活性、药动学、残留及毒性、临床应用等最新资料进行综述。     

Land-cover and structural changes in a western Norwegian cultural landscape since 1865, based on an old cadastral map and a field survey

Many studies of land-cover and structural changes in cultural landscapes have used historical maps as a source for information about past land-cover. All transformations of historical maps onto modern coordinate systems are however burdened with difficulties when it comes to accuracy. We show that a detailed land survey of the present landscape may enable transformation of an old cadastral map directly onto the present terrain with very high accuracy. The detailed resulting map enabled us to locate remnants of semi-natural grasslands and man-made structures with continuity from 1865 and to test hypotheses about relationships between landscape changes and landscape characteristics. The main land-cover change 1865–2002 was decrease of arable fields, and addition of three new land-cover classes: horticultural, orchard and abandoned areas. Of the 330 man-made structures present in 1865, only 58 remained in 2002, while 63 new structures had been built after 1865. We found that semi-natural grasslands with continuity since 1865 were situated on ground with significantly lower production capacity than mean 1865 production capacity. The man-made structures with continuity since 1865 were also associated with areas with significantly lower production capacity than the 1865 mean, situated in significantly steeper terrain but not further from the hamlet. Our study illustrates the potential of digitised and accurately transformed historical cadastral maps combined with detailed field surveys for analysis of land-cover and structural changes in the cultural landscape.     

Neutral models for testing landscape hypotheses

Neutral landscape models were originally developed to test the hypothesis that human-induced fragmentation produces patterns distinctly different from those associated with random processes. Other uses for neutral models have become apparent, including the development and testing of landscape metrics to characterize landscape pattern. Although metric development proved to be significant, the focus on metrics obscured the need for iterative hypothesis testing fundamental to the advancement of the discipline. We present here an example of an alternative neutral model and hypothesis designed to relate the process of landscape change to observed landscape patterns. The methods and program, QRULE, are described and options for statistical testing outlined. The results show that human fragmentation of landscapes results in a non-random association of land-cover types that can be describe by simple statistical methods. Options for additional landscape studies are discussed and access to QRULE described in the hope that these methods will be employed to advance our understanding of the processes that affect the structure and function in human dominated landscapes.     

丁烯氟虫腈对小菜蛾的生物活性及田间防治效果

为系统地评价新药剂丁烯氟虫腈对小菜蛾的生物活性及环境因素对其应用效能的影响,在室内,建立了丁烯氟虫腈对小菜蛾幼虫的敏感毒力基线,测定了丁烯氟虫腈对小菜蛾卵的活性,测定了温度、龄期对其生物活性的影响以及对小菜蛾3龄幼虫的持效性,并进行了田间防治试验。结果表明,丁烯氟虫腈对小菜蛾具有较高的触杀毒力,48hLD50为0.45μg/头。用64mg/L丁烯氟虫腈药液浸渍,对小菜蛾卵的孵化抑制率为46.24%,且初孵幼虫存活率明显降低;丁烯氟虫腈对小菜蛾1～2龄幼虫的毒力较高,3龄以后随虫龄增大,敏感性降低;温度对丁烯氟虫腈毒力发挥有显著影响,表现明显的正温度系数效应,温度从15℃上升到32℃,毒力增强15.49倍。持效性试验表明,64mg/L丁烯氟虫腈对小菜蛾3龄幼虫的校正死亡率在84%～95%之间,持效15天以上。田间试验结果表明,丁烯氟虫腈对小菜蛾具有较好防治效果,以5%丁烯氟虫腈乳油1200倍液施药,药后1天防效达76%以上,药后7天在88%以上,与相同用量的同类药剂氟虫腈无差异显著性。     

红果米仔兰杀虫活性成分及毒力的初步研究

为探索楝科植物红果米仔兰的杀虫活性,本以生物活性跟踪法对该种植物的叶的活性成分进行了初步研究,并测定了活性物质对斜纹夜蛾幼虫的毒力。叶的甲醇抽提物活性高于氯仿抽提物和石油醚抽提物。甲醇抽提物经氯仿萃取,所得萃取物通过柱层析,分离得到的４号流份Ｆ４有最高活性。Ｆ４对斜纹夜蛾４龄幼虫的拒食中浓度（ＡＦＣ５０）为０．１２％,致死中浓度（ＬＣ５０）为０．１３％,抑制生长发育中浓度（ＥＣ５０）为０．２１％。