丁醚脲在甘蓝和花菜中的残留动态研究

[目的]研究丁醚脲在蔬菜中的残留检测方法和田间消解动态,为丁醚脲在蔬菜上的使用安全提供参考依据。[方法]结合Qu ECh ERS前处理技术和LC-MS/MS分析技术,开发建立丁醚脲在甘蓝和花菜中的检测方法,并采用田间试验方法研究丁醚脲在甘蓝和花菜中的残留消解动态规律。[结果]试验表明,在0.01~1.00 mg/kg添加水平范围内,甘蓝样品中的添加回收率在79.4%~86.8%,变异系数为4.6%~7.2%,花菜样品中的添加回收率在83.8%~88.5%,变异系数为5.1%~7.7%,检出限为2.5μg/kg。田间残留试验表明,丁醚脲在甘蓝和花菜中降解符合动力学曲线,丁醚脲在甘蓝和花菜中的消解半衰期分别为2.2和3.2 d。[结论]该试验方法进行甘蓝和花菜中丁醚脲残留测定,灵敏度高,重现性好,符合农药残留检测的要求。消解动态和最终残留试验结果结合我国和国外MRL值,建议推荐用量的丁醚脲在甘蓝和花菜中的安全间隔期为7 d,出口蔬菜中谨慎使用丁醚脲。     

薯干酒精废醪厌氧消化添加剂的研究

本试验采用正交试验法,研究了薯干酒废酸醪厌氧消化添加剂的组分和浓度范围。在批量发酵中,这种复合添加剂使产甲烷量增加12.65％,氢化酶活力提高40.11％.2.5升UASB—AF消化器的半连续运行中,有机负荷在4.60～19.60gCOD/L·d范围内,该添加剂使池容产气率增加31.53％～70.40%,COD去除率增加30.75％～89.33％,甲烷含量增加13.12％～29.07％。出水碱度与总酸之比值,试验柱为2.68～12.50,对照柱为1.03～4.78。两个有效容积各400m~3UASB—AF沼气池,相同条件下并列运行,试验池优于对照池,运行11天和25天的氢化酶活力分别提高13.84％和25.87％,一次性启动成功。     

Feeding activity of the earthworm Eisenia andrei in artificial soil

Quantitative information on the feeding activity of earthworms is scarce but this information is valuable in many eco(toxico)logical studies. In this study, the feeding activity of the compost worm Eisenia andrei is examined in artificial soil (OECD medium), with and without a high-quality food source (cow manure), and at two temperatures (10 and 20 °C). Methods are provided to estimate the most important parameters: gut load, selection of organic matter (OM), digestion efficiency, compaction, gut retention time, and fraction of manure in the diet. Lanthanides (Lu and Tm) were successfully used as inert markers in soil and manure, and we applied Bayesian statistics to analyse the data and fully capture the compounded uncertainty in the parameter estimates. Results show that the compost worm does not feed on soil indiscriminately but is able to select an OM-enriched diet from apparently homogeneous OECD medium. When manure is present on the soil surface, approximately three-quarters of the diet still consists of soil particles. The gut load of the worms was approximately 10% (dwt gut/wwt empty worm), varying little with the treatments. Unfortunately, the digestion efficiency could only be reliably estimated at 20 °C, and was approximately 40%. Temperature clearly affected feeding as a 10° temperature decrease nearly doubled the gut retention time (from 2.9 to 5.5 h), which corresponds to a two-fold decrease in feeding rate. The present data may be used to interpret toxicity and accumulation studies with E. andrei in OECD medium. However, care must be taken, as it seems possible that feeding is influenced by the size of the worm and subtle differences in experimental set-up.     

LNK871凯氏定氮快速蒸馏器与半微量凯氏定氮仪的比较试验

对LNK871凯氏定氮快速蒸馏器和半微量凯氏定氮仪在蒸馏测定结果、蒸馏时间、回收率三个方面进行了比较试验。     

一次性消化测定饲料中粗蛋白、钙、磷的研究

本文采用硫酸—过氧化氯消化样品，连续测定饲料中的粗蛋白、钙、磷的含量，经过比较，此方法简便易行，结果令人满意     

Genetic Correlations Between Beef Traits Measured on Young Performance Test Bulls and Daughter Milk Yield

In a breeding programme where young potential breeding bulls are reared on performance test stations, selection based on own results can be carried out before test inseminations. Both beef and milk production traits are included in the total merit index used for selection, and estimates of genetic and phenotypic parameters of these traits are therefore of interest for an optimal construction of such indices. Data on first lactation milk records from the field and beef records of potential dairy breeding bulls from the Danish performance test stations were analysed in bivariate animal-sire models using the AI-REML algorithm. Genetic correlations of 0.16, 0.25 and 0.43 between feed intake capacity and protein yield were obtained for Red Danish (RD), Danish Black and White (DBW) and Danish Jersey (DJ), respectively. These correlations were significantly different from zero for the two populations (DBW and DJ). Genetic correlations around zero between feed efficiency and protein yield were obtained for all three populations. Genetic correlations of 0.44, 0.19 and 0.47 between average daily gain and protein yield were obtained for RD, DBW and DJ, respectively. The genetic correlations between protein yield and muscle area was close to zero for DBW, while it was -0.31 for RD. Selection index calculations indicate that indices composed of different beef performance traits can be used as early predictors for milk yield. Selection on such an index could increase the breeding value of the young bulls for milk production traits by 0.8-2.0% of the population mean.     

橡胶厂废水·污泥在蔬菜生产中的应用研究

[目的]橡胶厂废水、污泥富含氮、磷、钾、钙、镁等营养元素,探索其在蔬菜生产中的应用。[方法]在空心菜(Ipomoea aquatica For-sk.)上进行田间试验。[结果]橡胶厂废水、腐熟污泥均具有一定肥效,施用腐熟污泥、灌溉橡胶厂废水能增加土壤有机质含量,提高土壤肥力,种植的空心菜生长势较好,植株较高,叶色浓绿,叶绿素含量较高,空心菜产量增加了60.9%～132.2%。[结论]该研究可为橡胶厂废水、腐熟污泥在蔬菜生产中的推广应用提供科学依据。     

2种消解仪不同消解条件对凯氏定氮法测定结果的影响

为了确保不同消解仪准确测定土壤全氮,对2种消解仪的消解条件进行分析讨论。结果表明,红外消解仪适宜设定温度为370℃,石墨炉为380～400℃。氮质量分数为0.237～8.8 g/kg的样品,红外消解仪的适宜消解时间为57～107 min,石墨炉为60～114 min;2种消解仪的适宜消解温度和消解时间存在一定差异,这与消解仪加热方式、消解管尺寸及受热面积、升温速度等密切关联。2种消解仪在适宜温度及时间条件下消解样品,检测准确稳定,所测全氮趋于一致,两者相关性良好(R~2=0.999 9)。因此,不同消解仪的适宜消解条件应结合具体情况,通过一系列试验选择确定。     

TMR粒度对日粮消化率与奶牛生产性能的影响

TMR粒度对奶牛健康养殖起着至关重要的作用,本研究选取泌乳天数、胎次、产奶量相近的200头奶牛进行配对试验,饲喂不同粒度的相同日粮,采集粪样、记录干物质采食量、收集DHI数据进行配对T检验分析。结果表明,TMR粒度较大的试验组奶牛日粮消化率较高,产奶量及乳脂率有升高的趋势,但差异不显著。     

Determination of Total Nitrogen in Solid Samples by Two-Step Digestion–Ultraviolet Spectrophotometry Method

A two-step digestion–ultraviolet (UV) spectrophotometry method for total nitrogen (N) determination in solid samples is described in this work. Three influencing factors (amount of hydrogen peroxide, amount of sulfuric acid, and digestion time) of the digestion are optimized, and for digestion of a 0.1-g solid sample, the optimal conditions are 0.5 mL of sulfuric acid, 0.2 mL of hydrogen peroxide, and 40 min of the digestion time. The results of ion chromatography show that under the optimal conditions the organic nitrogen almost quantitatively mineralizes into ammonium in the first digestion. The nitrogen content in six real samples has been analyzed under the optimal conditions, and the nitrogen recovery rates of standard compounds added in the real samples were between 88% and 99%. The results obtained by two-step digestion–UV spectrophotometry method are consistent with those by classical Kjeldahl method (correlation coefficient is 0.9999). The possible degradation pathways of three amino acids were also proposed.