南宁市常见绿化树种滞尘综合效应研究

选择南宁市友爱立交、民族大道、白沙大道3个区域的7种常见道路绿化树种,测定分析了植物叶面滞尘能力、植物抗性的差异,并选取与植物滞尘效应密切相关的植物高度、叶面积指数、单位面积滞尘量、植物抗性和叶面特性等7个分类指标,采用综合指数法对南宁市常见道路绿化树种的滞尘效应进行评价。结果表明,7种绿化树种滞尘能力大小依次为：黄金榕〉大叶红草〉鱼尾葵〉白兰〉七彩朱槿〉垂叶榕〉扁桃;抗性能力大小依次为：黄金榕〉扁桃〉白兰〉垂叶榕〉鱼尾葵〉七彩朱槿〉大叶红草;滞尘综合效应高低依次为：白兰〉鱼尾葵〉扁桃〉黄金榕〉垂叶榕〉七彩朱槿〉大叶红草。     

Loss of reserves of Cu in liver when Cu supplements are withdrawn from dairy herds in the Waikato region

Abstract

AIM: To monitor the consequences of withdrawing mineral Cu supplements from two dairy herds with initially high concentrations of Cu in liver.

METHODS: Two herds were selected from dairy farms in the Waikato region of New Zealand that participated in an earlier survey of Cu supplementation practices and Cu status of dairy cows. The herds were fed pasture, grass and maize silage, plus palm kernel expeller (PKE) containing 25–30 mg Cu/kg dry matter (DM) fed at 2–4 kg/cow/day. No mineral Cu supplements were supplied from January 2009. Pasture samples were collected for mineral analysis in September 2008 and April 2009. Concentration of Cu in liver biopsies from the same 9–10 cows per herd was measured on three occasions between April 2009 and May 2010.

RESULTS: Pastures on both farms contained 10 mg Cu/kg DM, 0.1–0.5 mg Mo/kg DM and 3.5–4.0 g S/kg DM. The initial herd mean concentrations of Cu in liver were 1,500 (SD 590) and 1,250 (SD 640) μmol Cu/kg fresh tissue. In the absence of mineral Cu supplements, those mean concentrations decreased over 12 months to 705 (SD 370) and 1,120 (SD 560) μmol Cu/kg fresh tissue, respectively. For cows in the first herd, the rate of depletion of liver Cu reserves was influenced by initial concentration of Cu, such that high concentration led to faster loss according to first-order kinetics.

CONCLUSIONS: Mineral Cu supplementation was not necessary over 12 months for two dairy herds with mean concentrations of Cu in liver >1,250 μmol Cu/kg fresh tissue, grazing pastures containing 10 mg Cu/kg DM and concentrations of Mo <1 mg/kg DM. The quantity and particularly the duration of feeding PKE appeared to be a factor in whether or not the herd lost substantial reserves of Cu in liver during the year. However, the Cu status of both herds in this study was more than adequate to support late pregnancy and mating.

CLINICAL REVELANCE: Copper status of the herd should be monitored and on-farm management of Cu nutrition should take into account all sources contributing to daily intake of Cu. Where Cu supplementation has been excessive and there is risk of chronic Cu toxicity, mineral Cu supplements may be withdrawn for a period commensurate with the expected rate of liver Cu depletion.     

Habitat utilisation,growth and predation of Cucumaria frondosa: implications for an emerging sea cucumber fishery

Abstract Biological traits of the sea cucumber Cucumaria frondosa (Gunnerus) relevant to both ecological and management perspectives were investigated in the Newfoundland region. Abundance, size and fitness of adults were maximal on hard substrates. Larvae settled ～5 weeks post‐spawning and juveniles reached a maximum length of 6 mm after 24 months. Additional size classes of sea cucumbers kept under natural environmental conditions exhibited slow seasonal growth attuned to phytoplankton blooms, indicating that ～25 years may be required to reach market size. Juveniles of the predator sea star Solaster endeca (L.) readily fed upon 1.5‐2 mm long sea cucumbers. Predation rates on adult C. frondosa by adult S. endeca were modulated by temperature and biased towards injured specimens, suggesting that trawling may exacerbate predation pressure. The combination of slow growth and high predatory pressure enhanced by fishing activities emphasises the need for precautionary management of this emerging fishery in Atlantic Canada.     

天津市无公害农产品生产发展现状及对策

农产品质量安全问题是新阶段农业和农村经济工作中必须解决的问题,全面发展无公害农产品对增强农业综合竞争力、增加农民收入、推进农业增长方式转变具有重大意义。阐述了天津市无公害农产品发展历程和现状,分析了发展过程中存在的问题。同时,提出推进天津市无公害农产品可持续发展的对策和建议:应发挥在无公害农产品发展上起步早、基础好的优势,加大科技创新和技术推广力度,建立无公害农产品生产标准化体系,全面推行市场准入制度,发展优势无公害农产品规模基地建设,大力发展产业化经营。     

Adding nutritional value to meatand milk from pasture-fed livestock

Staple meat and milk provide excellent nutrition, but when traditional foods and ingredients are tailored to meet the particular nutritional or lifestyle demands of a population they become even more attractive and valuable. These foods can be considered as delivery systems for health-promoting nutrients. Nutritional improvement of meat and milk can be achieved several ways, preferably by making desirable changes on-farm to directly improve the food without subsequent manipulations. Scope for these changes is limited by animal homeostasis, but alternatives may be less desirable. Methods in vivo that suit typical pastoral farming practice and can complement the solving of animal health and production problems include: selection of traits or phenotypes; specialty diets; long-acting parenteral supplements; and modification of ruminal microflora. Successful techniques to increase the concentration of calcium, selenium, iodine and iron in milk or meat are described.

Manipulations to change composition are only one part of bringing tailored foods to market. Commercial realisation of these new products needs the initiative and collaboration of scientists, veterinarians, growers and producers responding to market pull. The uptake of future biotechnologies to capture more value inside the farm gate will also be required if the pastoral industry in New Zealand is to sustain a global competitive advantage.     

Field trial of a synthetic tsetse-repellent technology developed for the control of bovine trypanosomosis in Kenya

We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to evaluate the effectiveness of a synthetic tsetse-repellent technology developed for the control of trypanosomosis in cattle. The technology was a repellent (2-methoxy 4-methylphenol) emitted from dispensers attached to collars worn by cattle. Treatment was allocated at the herd level to ensure adequate protection of all the animals in a herd, with measurements of effectiveness conducted at the individual-animal level. The trial began in April 2005 and ran for 16 months including a baseline phase of 4 months. We recruited 12 herds in each area using a restricted random-sampling technique and distributed them equally into intervention (repellent) and control groups. Sample size was determined using a formal power calculation. Effectiveness or minimal worthwhile difference was defined as a 50% reduction in the incidence of trypanosome infection in the treated versus control group (effectiveness below which the technology was considered by experts as not viable compared to existing control techniques). All the animals in the recruited herds were screened monthly (buffy-coat technique) for trypanosome infections. The analysis followed the principle of intention-to-treat by which subjects are analysed according to their initial treatment assignment, regardless of the mechanical performance of the device. Crude and adjusted effects of the technology were 23% (p<0.001) and 18% (p=0.08) reduction in the infection incidence in the treatment compared to the control groups, respectively. The impact of the technology estimated in this study did not achieve the threshold of 50% reduction in the trypanosome infection incidence set a priori to indicate effectiveness (p<0.001). We therefore concluded that the prototype repellent technology package was not sufficiently effective in reducing trypanosome infection incidence under natural tsetse challenge to merit commercial development.     

贮存时间对成熟苦瓜生理特性影响的初步研究

以新鲜成熟苦瓜160-2为材料,初步研究了常温下,不同贮存时间内,苦瓜果实外观、硬度以及可溶性蛋白质、可溶性糖、Vc、水分含量和SOD和POD活性的变化.结果表明:常温下贮存的苦瓜果皮易黄化,随着贮存时间的延长,果实硬度、水分含量与Vc含量一直呈下降的变化趋势,而果实中可溶性蛋白质与可溶性糖的含量、SOD和POD的活性则呈先上升后下降的变化趋势.