Factors influencing decline in soil pH in Hawaiian Eucalyptus and Albizia plantations

Soil pH declined from 5.9 to 5.0 in 8 years beneath plantations of Eucalyptus saligna (Sm.) in Hawaii. In stands of Albizia falcataria, (L.) Fosberg, the soil pH change was more dramatic, declining from 5.9 to 4.6. We measured several components of soil acidity beneath four mixtures of the two tree species to gain insight on the processes responsible for the decline in soil pH. These components were studied using an empirical method of comparing acid quantity, degree of neutralization (depletion of base cations), and acid strength. The decline in soil pH differed between species as a result of differences in the degree of neutralization of the soil exchange complex; the larger decrease in soil pH under Albizia was produced by greater acidification of the exchange complex. Empirical titration curves suggested that differences in acid strength moderated the divergence in soil pH beneath the species. Had the acids accumulating in the soil under Albizia been as strong as those in the Eucalyptus soil, the difference in soil pH would have been greater. Though the two species had contrasting effects on soil pH, the differences in degree of neutralization, responsible for the pH decline, were small compared with differences in the amount of cations stored in tree biomass. Continued supply of nutrient cations (from weathering or fertilization) will ultimately control both the extent of soil pH decline and the level of productivity sustained by the forest.     

Studies on mutlispecific resistance of gastrointestinal nematodes to benzimidazoles on dairy-goat farms

Multispecific resistance to benzimidazoles was studied in three selected farms. These farms had bred dairy goats for more than 15 years. The helminths were introduced with the goats at the establishment of the farms which afterwards remained isolated. Nematode resistance could then be related to their own management practices. Faecal egg count tests and egg hatch assays were performed to assess intensity of resistance. The generic (infective larvae in faecal cultures) and specific richness (adult worms) were assessed. The resistant species were Trichostrongylus colubriformis, Teladorsagia circumcincta, Haemonchus contortus and Oesophagostomum venulosum. Faecal egg count reduction tests and egg-hatch assays did not match exactly. Faecal larval counts after treatments gave a distorted picture of multispecific resistance: Haemonchus and Oesophagostomum were very largely over represented. The number of species found in the three farms was relatively low compared with other reports in goat farms of the area. This reduction of diversity might also be due in part to characteristics of breeding management and history (use of permanent pasture and introduction of goats at the establishment of farm).     

双孢蘑菇2796菌丝生物学特性研究

研究了双孢菇2796菌丝的生物学特性。结果表明，菌丝生长的最适碳源为麦芽糖，最适氮源为(NH4)2SO4；最适温度为20--25℃；培养基最适含水量为60--65％；最适pH为6—7；菌丝在黑暗条件下生长良好，光照抑制菌丝生长；适宜的CO2浓度可刺激菌丝的生长。     

矸酆恐?,垩白率与糙米率、蛋白

Χ灾绷吹矸酆康挠跋焓钦?,直接影响比间接影响大。Study on the correlation between rice quality and agronomic traits of quality riceNIE Cheng rong, WEN Yu hui, WANG Yun bo, CHEN Ming zhong,LI Mei, LIU Dao quan(Agronomy Department, Foshan University , Nanhai 528231,China)The correlative analy     

13～18周龄笼养蛋鸭适宜蛋白质和蛋氨酸水平的研究

用 32 4羽满 1 2周龄的金定鸭 ,通过饲养试验、代谢试验、屠宰试验和对试鸭产蛋期 (1 9～ 2 8周龄 )产蛋性能的观察 ,研究了在等能条件下(ME :1 1 51MJ/kg) ,不同蛋白质水平 (CP :1 3 %、 1 5 %、 1 7% )和蛋氨酸水平 (Met/CP :0 0 1 7、 0 0 2 2、 0 0 2 7)组成的 9种饲粮对 1 3～ 1 8周龄笼养蛋鸭的生长性能、养分利用、体成分沉积和产蛋期产蛋性能的影响。结果表明 :该阶段饲粮粗蛋白、蛋氨酸水平对体增重影响不显著 (P >0 0 5) ;体增重与蛋氨酸 (% )呈一定的正相关 (r=0 4574) ;CP为 1 3%、Met/CP为 0 0 2 7组采食量一直较稳定、较高 ,且饲料效率又好。代谢试验 :不同粗蛋白、蛋氨酸水平饲粮对试鸭氮存留率和能量的利用率影响显著(P <0 0 5或P<0 0 1 ) ,且它们随饲粮CP水平的升高而降低 ,随蛋氨酸水平升高而升高 ;磷的利用率也分别以CP为 1 3%的水平和Met/CP为 0 0 2 7的水平极显著地高于其他水平对磷利用率 (P <0 0 1 )。屠宰试验 :当Met/CP为 0 0 2 7时 ,体氮沉积量和体磷沉积量最佳。产蛋性能 :开产日龄和高峰日龄与 1 3～ 1 8周龄CP食入量呈弱的负相关 (r=- 0 1 83 3和r=- 0 0 984) ,与蛋氨酸食入量呈正相关 (r =0 5780和r =0 435 0 )。饲粮粗蛋白、蛋氨酸水平对 1 9～ 2 8周龄     

中等职业学校专业设置原则的研究

在分析我国职业教育的发展现状、职业学校专业设置现状及发展趋势、影响专业设置因素等情况的基础上 ,提出了职业学校设置专业时应处理好的几个关系 ,应遵循的一般原则及相应的审批程序。     

Mycoplasma hyopneumoniae colonization of pigs sired by different boars

Differences in Mycoplasma hyopneumoniae colonization were evaluated in experimentally inoculated pigs sired by 3 different boars of the same genetic line. Forty-six pigs were used, including a treatment group and positive and negative control groups. The pigs were intratracheally inoculated with an M. hyopneumoniae suspension or with Friis media as a placebo. To evaluate differences in the magnitude of colonization during a 35-day period, nasal and tracheal swabs were collected weekly and tested by nested polymerase chain reaction (N-PCR). Temperature, weight and circulating antibodies were measured for 35 days. At 11 and 35 d postinoculation the pigs were necropsied and macroscopic and microscopic lesions were determined. A section of bronchus was tested by the indirect immunofluorescence test (IFAT), scanning electron microscopy (SEM) and N-PCR. The N-PCR results from the nasal and tracheal swabs showed that the pigs sired by one boar (B3) had a distinctive colonization pattern, different from that of the pigs from the other 2 boars and from the positive controls. SEM studies demonstrated that at 35 d postinoculation a higher proportion of B3 pigs had lower numbers of mycoplasmas attached to the cilia compared with B1 and B2 offspring. No significant differences were observed in temperature and weight gain among groups by ANOVA; however, with use of a 2 × 2 table, temperature differences were observed between pigs sired by boars B1 and B2 at 4 d postinoculation. No pigs seroconverted, showed gross or microscopic lesions, or had positive IFAT results. These results provide evidence of differences in patterns of colonization between pigs sired by different boars, suggesting a possible genetic effect.     

高效液相色谱法测定齿毛芝中的碱基

采用250SS4.6-ODSZ-8/5色谱柱,体积分数20%的甲醇为流动相,紫外260nm检测,尿嘧啶,尿苷,腺嘌呤腺苷的保留时间分别为2.23min,2.97min,4.13min和6.74min,检测齿毛芝中碱基的摩尔比依次为1`.24:0.41:2.29:2.05.     

The effect of exploratory laparotomy on the serum and peritoneal haptoglobin concentrations of the pony.

Serum haptoglobin concentration was used as an indicator of the acute phase response in ponies undergoing exploratory laparotomy. Preoperative, 1 h intraoperative, 3 h, 6 h, 12 h and 24 h postoperative blood samples and 48 h postoperative peritoneal fluid samples were obtained for haptoglobin analysis. A spectrophotometric assay based on cyanmethemoglobin binding capacity (CyanBC) was used to determine haptoglobin concentrations. The preoperative reference range for serum haptoglobin concentrations in these ponies was 25-60 mg CyanBC/dL. Intraoperative and 3 h postoperative blood samples had decreased haptoglobin concentrations when compared to preoperative values. Serum haptoglobin concentrations began to rise by the 6 h postoperative sample and were generally elevated above preoperative values by the 24 h postoperative sample. Two of the ten ponies had mild signs of postoperative colic which were associated with twofold elevations in serum haptoglobin concentrations and fivefold elevations in peritoneal fluid haptoglobin concentrations.