Pharmacokinetics of cefquinome in tilapia (Oreochromis niloticus) after a single intramuscular or intraperitoneal administration

The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two‐compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half‐life (T_1/2ka) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half‐life (T_1?2β) was calculated to be 5.81 h, the maximum plasma concentration (C_max) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (T_max) to be 0.14 h, and the area under the plasma concentration–time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL.     

基于Gottingen翼型的离心泵前置导叶预旋调节试验

运用轴流泵孤立叶片设计方法,设计了基于Gottingen翼型的前置导流叶片,并对离心泵预旋调节的基本规律及调节机理进行了试验研究.通过对比前置导叶的不同安装方式对单吸离心泵效率、功率的影响,发现单吸离心泵采用前置导叶长弦端靠近中心轴的安装方式对离心泵外特性的改善效果要优于前置导叶短弦端靠近中心轴的安装方式,而且长弦端靠近中心轴安装方式前置导叶能够有效拓宽离心泵的高效运行范围,改善其在非设计工况下的水力性能,且与无前置导叶工况相比,最高效率可提高2.3％,从而达到为离心泵增效节能的目的.     

生物质育苗钵及成型装备

针对植物育苗对泥炭资源的大量需求,从泥炭资源保护和可再生资源利用的角度出发,以农作物秸秆作为主要基质原料生产育苗钵,并设计了相应的基质装载成型装备.通过实验研究表明,农作物秸秆作为育苗钵基质具有良好的发展前景,基质装载成型装备的开发应用为高效批量生产育苗钵奠定基础.     

农产品视频履历追溯系统设计

针对目前农产品追溯系统中履历信息单一化和信息量少的问题,设计了一个以实现生产过程中质量追溯为目的的农产品视频履历追溯系统.基于ARM9嵌入式技术与H.264压缩技术相结合对农产品生产过程进行视频履历的采集和压缩处理,应用3G无线传输技术对视频履历进行传输,通过生产服务器对视频履历进行存储,以.NET为平台开发了用户对农产品视频履历追溯系统的软件.该系统可采集农产品生产过程各个阶段的视频履历,为农产品追溯提供了更直观、更丰富、更具说服力的履历信息.该系统运行结果表明,系统具有通用性强、可靠性高、稳定性好、便携式等特点,可方便地应用于温室、农田等各种农产品生产的环境,从而满足用户的不同需求.     

葡萄资源叶片抗炭疽病鉴定及抗病基因的QTL定位

【目的】炭疽病是葡萄的主要病害之一,极易造成大规模的病害流行,严重影响葡萄产量及品质,筛选抗病种质及挖掘抗病基因有利于葡萄抗病机制研究及抗病育种的开展。【方法】利用室内离体叶片接种法,对60份中国野生葡萄种质、122份欧亚种质、76份欧美杂种以及美人指×刺葡萄0940的F1代杂交群体进行炭疽病抗性鉴定与评价,并利用SNP标记构建的遗传图谱对炭疽病抗性进行QTL定位。【结果】经抗性鉴定,共筛选出1份高抗、43份抗病和75份中抗种质,分别占总鉴定种质的0.39%、16.67%和29.07%。以筛选出的抗病种质刺葡萄0940和感病种质美人指的杂交后代为分离群体进行QTL定位,在第8号连锁群上检测到一个与抗炭疽病相关的QTL位点,可解释14.7%的表型变异。根据QTL定位区间基因注释结果,筛选出15个抗病相关基因,推测它们在葡萄抗炭疽病中发挥一定作用。【结论】明确了不同葡萄种质的炭疽病抗性水平,定位到1个抗炭疽病QTL位点并筛选出15个抗病相关基因。     

Soil nitrogen and denitrification potential as affected by land use and stand age following agricultural abandonment in a headwater catchment

Changes in vegetation and soil properties because of agricultural abandonment may affect soil nitrogen (N) and associated processes. We investigated soil N (total N: TN, inorganic N: NH₄–N and NO₃–N) and denitrification potential in cropland, pine plantations and abandoned agricultural land along a secondary succession sequence (grassland→shrubland→secondary forest) in a headwater catchment in the Qinling Mountains, northwest China. The results show that the soil denitrification potential differed significantly among the five land‐use types with the highest potential in the secondary forest, followed by grassland, shrubland, cropland and plantations. The denitrification potential of the 20‐ to 40‐cm layer was significantly lower compared with the topsoil (0–20 cm) across all land‐use types. TN, soil organic matter (SOM) and NH₄–N increased significantly with stand age, whereas there was an opposite trend in soil pH. However, the denitrification potential did not relate to stand age in a linear manner. We conclude that changes in soil TN, SOM and pH during vegetation succession following agricultural abandonment are critical controls on the denitrification potential.     

Soil organic‐C accumulation and N availability under improved pastures established in Mediterranean oak woodlands

Long‐term effects of improved pasture establishment (with high proportion of legumes) on soil organic‐C status and N availability in Mediterranean cork oak (Quercus suber L.) woodlands were assessed. Soils were sampled beneath scattered crowns and in open areas, considering two systems: unmanaged and managed woodlands where improved pastures were installed 26 and 32 years ago. Total and labile C and N pools were measured and C and N mineralization were determined over 24 weeks laboratory incubation. Soils under improved pastures showed higher organic‐C, total‐N and net N mineralization than those under unmanaged pasture, mainly when established beneath trees. Potentially mineralizable C, C mineralization rate and microbial C were not statistically different between the unmanaged and improved pasture sites, but were higher closer to the tree than in the open area (1.8, 1.2 and 1.2 times, respectively). The qCO₂ was higher in improved pastures (1.7 times). Labile pool of C and N extracted with hot water increased under improved pasture (3.4 and 1.7 times, respectively). Results indicate that soil quality amelioration by improved pastures is stronger in the presence of oak trees. Management systems that favour oak tree maintenance and regeneration should be taken into account to reverse soil degradation.     

Effects of Moringa oleifera silage on milk yield,nutrient digestibility and serum biochemical indexes of lactating dairy cows

This study investigated the effects of Moringa oleifera (MO) as a partial substitute of alfalfa hay on milk yield, nutrient apparent digestibility and serum biochemical indexes of dairy cows. MO was harvested at 120 days post‐seeding. Fresh MO was cut, mixed with chopped oat hay (425:575 on a DM basis), ensiled and stored for 60 days. Sixty healthy Holstein dairy cows were allocated to one of three groups: NM (no MO or control), LM (low MO; 25% alfalfa hay and 50% maize silage were replaced by MO silage) or HM (high MO; 50% alfalfa hay and 100% maize silage were replaced by MO silage). The feeding trial lasted 35 days. The LM and HM diets did not affect dry matter (DM) intake, milk yield or milk composition (lactose, milk fat, milk protein and somatic cell count). The apparent digestibility of DM and NDF was lower for HM group than NM group. Additionally, there were no significant differences in serum biochemical indexes between the LM and NM groups. The HM group had lower serum concentrations of total cholesterol, high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol and higher serum concentrations of urea than the NM group. The partial replacement of alfalfa hay (≤50%) and maize silage with MO silage had no negative effects on milk yield, in vivo nutrient apparent digestibility or serum biochemical indexes of lactating cows.     

Computer image analysis of intramuscular adipocytes and marbling in the longissimus muscle of cattle

The deposition of fat in muscle, recognized by the consumer as marbling, is an important meat quality trait. The objective of the study was to provide additional insights into the quantitative extent of marbling by means of computer image analysis. Fifty-one F(2) generation German Holstein and Charolais crossbreed cattle, 18 mo of age, were used to determine relationships among marbling traits, adipocyte size, and the amount of adipose tissue in different depots. Differences were recorded among the size of i.m. adipocytes in different groups of marbling flecks, divided according to the location in the muscle cross-section and to the size of the marbling flecks. The results showed positive correlation between i.m. adipocyte size and the weight of s.c. fat, intestinal fat, omental fat, and perirenal fat (r = 0.50, 0.61, 0.70, and 0.63, respectively, P < 0.001). The i.m. adipocyte size was correlated with i.m. fat content, number of marbling flecks, proportion of marbling fleck area, and total length of marbling flecks (r = 0.71, 0.44, 0.62, and 0.55, respectively, P < 0.01). The number of marbling flecks was also correlated with i.m. fat content, proportion of marbling fleck area, and total length of marbling flecks (r = 0.58, 0.62, and 0.91, P < 0.01, respectively). The ventral marbling flecks had a 5-fold larger fleck area, 4-fold more adipocytes, and larger adipocytes (P < 0.001). Larger marbling flecks contained larger adipocytes (P < 0.001). Moreover, compared with the small marbling flecks, there was a 48-fold larger fleck area and 26-fold more adipocytes in the large marbling flecks. The results indicate that i.m. fat deposition increases concurrently with the other fat depots but is still independent. Furthermore, the i.m. fat is preferentially deposited in the ventral area of LM. Although the i.m. adipocyte size has an important effect on the traits of marbling flecks, cell number plays a greater role in i.m. fat deposition than cell size.