Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica II. Cacao and wood production,litter production and decomposition

During 7 years (1979–1985) cacao harvests (beans and husks) have been recorded for the agroforestry systems ofTheobroma cacao underCordia alliodora andErythrina poeppigiana shade trees. The mean oven dry cacao yields were 626 and 712 kg.ha⁻¹.a⁻¹ cocoa beans underC. alliodora andE. poeppigiana respectively. Harvests have gradually increased over the years and the plantation has now reached maturity. Annual extraction of N, P, K, Ca and Mg in fruits, which is relatively small, was calculated on the basis of chemical analyses. The following average values were found (kg.ha⁻¹.a⁻¹): At the age of 8 years, theC. alliodora trees have reached 26.7 cm diameter (DBH) and 14.0 m in height. Mean annual growth (from age 5 to 7) is 14.6 m³.ha⁻¹.a⁻¹. Natural plant residue production has been measured for 4 years (Nov. 1981–Oct. 1985). UnderE. poeppigiana it has reached a value of 8.91 t.ha⁻¹.a⁻¹ and underC. alliodora 7.07 t.ha⁻¹.a⁻¹. The shade trees have contributed 57 and 47% respectively. Transference and decomposition rates are high and important in the nutrient cycles. The nutrient content of the litter was analysed and corresponding average yearly transfers were (kg.ha⁻¹.a⁻¹): For part I see Vol. 4, No. 3, 1986. Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesselschaft für Technische Zusammenarbeit), Turrialba, Costa Rica     

常绿和落叶阔叶树叶中N和P的变化及转移

从叶完全展开到生长季结束对常绿阔叶树种铁冬青、红楠和海桐及落叶阔叶树种日本朴、银杏和木叶的N和P浓度进行了定期测定。结果表明,常绿阔叶树种新叶的N和P浓度从5—7月急剧下降,然后小幅波动,而老叶的N和P浓度变化缓慢。落叶阔叶树种的N和P浓度随着季节的推移而明显下降。大多数树种的P转移率大于N转移率。常绿阔叶树种的N和P的转移率大于落叶阔叶树种。     

饲粮非植酸磷水平对39~46周龄黄羽肉种母鸡繁殖性能、胫骨指标和血浆生化指标的影响

本试验旨在研究不同非植酸磷( NPP)水平对39~46周龄黄羽肉鸡父母代种鸡繁殖性能、胫骨指标和血浆生化指标的影响,探讨该阶段适宜磷供给量。试验选用39周龄岭南黄羽肉鸡父母代种母鸡810只,根据体重和产蛋率分为5个组,每组6个重复,每重复27只鸡。组1为对照组,饲喂玉米-豆粕型基础饲粮( NPP水平为0.30%),组2、3、4和5饲粮分别在基础饲粮中添加不同水平的磷酸氢钙,使饲粮NPP水平分别为0.35%、0.40%、0.45%和0.50%,其他营养成分各组基本一致。试鸡限饲122 g/(只·d),自由饮水。试验期8周。结果表明：1)试验期内, NPP水平未显著影响试鸡平均日增重、平均日产蛋量、料蛋比、平均蛋重和破蛋率(P>0.05),显著影响了产蛋率和不合格蛋率(P<0.05),0.45%组产蛋率显著高于0.30%和0.40%组(P<0.05),0.40%组不合格蛋率显著低于其余4组(P<0.05)。2)饲粮 NPP水平显著影响了试鸡39~40周龄种蛋长径、蛋短径、蛋形指数和蛋壳强度(P<0.05),显著影响了45~46周龄种蛋蛋壳强度( P<0.05)。3) NPP水平对种蛋孵化性能(受精率、孵化率、健雏率、健雏平均出壳重)无显著影响(P>0.05)。4)饲粮 NPP 水平显著增加了试鸡脱脂胫骨粗灰分中钙、磷含量(P<0.05)。5)0.40%和0.45%NPP组试鸡血浆甲状旁腺激素含量显著高于0.30%和0.35%组( P<0.05),0.50%组血浆降钙素含量显著高于其余4组( P<0.05)。综上,39~46周龄黄羽肉鸡父母代种母鸡饲粮NPP适宜水平为0.40%~0.45%,根据采食量计算得到每日NPP需要量为0.488~0.549 g。     

玉米-杂粕型日粮中添加不同植酸酶对蛋鸡生产性能和蛋品质及钙磷代谢的影响

选取720只24周龄海兰褐蛋鸡,随机分为8个处理,每个处理6个重复,每个重复15只鸡。8个处理分别为正对照组(PC)饲喂有效磷为0.36%的正常基础日粮,负对照组(NC)饲喂有效磷为0.16%的低磷日粮,其余试验组是在NC组日粮基础上分别添加两种植酸酶A或B各125、250、500 U/kg。其中植酸酶A是从大肠杆菌中提取,植酸酶B是从里氏木霉中提取。试验期为12周。结果表明:与PC组比较,NC和B500组产蛋率、平均蛋重和日采食量显著降低(P0.05),其他各添加植酸酶组恢复到PC组水平,各添加植酸酶组料蛋比和蛋品质无显著变化(P0.05);与PC组相比,NC组胫骨灰分、胫骨磷和血浆磷含量显著降低(P0.05),添加2种植酸酶组(除B500组外)恢复到PC组水平,B500组血浆磷含量显著低于PC组(P0.05),各试验组胫骨钙含量和血浆钙含量与PC组无显著差异(P0.05)。结果提示,低磷玉米-杂粕型日粮中添加2种植酸酶都能够缓解低磷引起的负效应,但2种植酸酶的最佳添加量不同,本试验条件下日粮中添加125 U/kg的植酸酶B或250 U/kg的植酸酶A都能满足蛋鸡对无机磷的需求。     

Preliminary evaluation of Community-Led Total Sanitation for the control of Taenia solium cysticercosis in Katete District of Zambia

Taenia solium taeniasis/cysticercosis is a zoonotic disease endemic in sub-Saharan Africa. It is associated with poor sanitary practices, free-range pig husbandry and lack of disease awareness in endemic communities. A comparative research was conducted with pre and post-intervention assessments in nine villages to evaluate Community-Led Total Sanitation (CLTS) as an intervention measure for the control of porcine cysticercosis in Katete District in the Eastern Province of Zambia. Blood samples were collected from pigs for circulating antigen detection and a questionnaire focused on the household was administered to a total of 153 respondents whose pigs were examined (64 pre-intervention, 89 post-intervention), in order to obtain information on general demographic characteristics, pig husbandry practices, sanitation practices and associated knowledge and awareness of T. solium infections. The first sampling was conducted prior to the implementation of the CLTS and second sampling eight months after triggering of CLTS in the selected villages. A total of 379 pig serum samples were examined using the B158/B60 Ag-ELISA to detect T. solium cysticercosis, 104 pre-intervention and 275 post-intervention, of which 14 (13.5%) and 45 (16.4%) were positive, respectively. Wald test p-values were computed to assess significant differences in the variables of interest mentioned above for the pre and post CLTS. The research revealed that CLTS as a control measure did not significantly improve T. solium infections in pigs. The research also revealed that the sanitation practices and awareness of cysticercosis did not change. It is recommended that a longer term evaluation be undertaken when the villages have been declared open defaecation free. In addition, the research recommends that health education, mass drug treatment and pig vaccination be incorporated, as an essential component of prevention and control programmes for T. solium infections.     

Demonstration of uniformity of calcium absorption in adult dogs and cats

A meta‐analysis was conducted to understand quantitative aspects of calcium (Ca) and phosphorus (P) absorption in adult dogs and cats. 34 studies in dogs and 14 studies in cats met the criteria for inclusion in the meta‐analysis. Intake and faecal excretion values of Ca and P were subjected to a modified Lucas test and subsequent regression analyses. According to the current scientific consensus, Ca true digestibility (absorption) should increase at low Ca intake and decrease at high Ca intake. If true, this should result in a nonlinear relationship between the percentage of Ca excreted and dietary Ca intake. The present meta‐analysis showed a highly significant linear relationship (p < 0.0001) between Ca intake and Ca excretion suggesting a lack of systematic quantitative adaptation in true Ca digestibility. This finding suggests either that the time period covered by standard digestion trials is too short to induce adaptation mechanisms or that dogs and cats at maintenance will not efficiently alter quantitative Ca absorption percentage according to the amount ingested. If the latter is true, a dietary Ca supply differing greatly from the recommended dietary intake might impair the health of cats and dogs when fed long term. The data plots for P intake and faecal excretion were less uniform suggesting other factors not just dietary intake influence faecal P excretion. In adult cats, the dietary Ca:P ratio strongly influenced the true digestibility of P, whereas this effect was less marked in adult dogs. Faecal P excretion was significantly correlated to faecal Ca excretion in both species (p < 0.0001), and surprisingly, the level of P intake did not appear to be an important determinant of true digestibility of P.     

贺兰山西坡不同海拔梯度草地土壤磷特征及其影响因素

对贺兰山西坡不同海拔的不同类型草地土壤磷素的空间分布特征以及环境及植被因素对土壤磷素的影响进行了研究。结果表明,0-10和10-20cm土层土壤全磷(TP)含量随着海拔由高到低而显著降低;两土层中,土壤全磷与土壤有机碳、土壤中0.05mm粘粉粒含量及植被盖度之间呈显著正相关(P0.05),土壤全磷沿土壤剖面的垂直分布没有一致规律性;土壤速效磷含量随着海拔高度和草地类型的变化没有呈现出一定的变化规律,两土层中土壤速效磷/全磷比值(AP/TP)与土壤pH值以及年平均气温呈显著正相关(P0.05),说明该区土壤pH值和温度的变化能显著影响土壤磷的活化;多数样地0-10cm土层速效磷显著高于10-20cm土层,可能归因于植物对磷素的表聚作用。     

Study on Effect of Nitrogen and Phosphorous on the Resistance of E.coli to Chloramphenicol and its Mechanism

This study was designed to explore the effect of nitrogen and phosphorous on the resistance of E.coli from environment and the mechanism.Microcosms were established to study the effect of nitrogen and phosphorous on the resistant phenotype of E.coli to chloramphenicol (CHL).cat gene of isolated drug-resistant strains and susceptible strains were detected.The results showed that,different concentration of nitrogen and phosphorous could induce the formation of antibiotics resistance of E.coli to CHL.The rate of cat gene of 46 strains of chloramphenicol resistant E.coli was 89.13%,which was 0 in the 16 strains of chloramphenicol sensitive E.coli.The results indicated that,nitrogen and phosphorous in the microcosms could induce the formation and maintenance of resistance to chloramphenicol in E.coli,which had correlation with cat gene.     

Soil phosphorus fractions and their availability over natural succession from clear-cut of a mixed broadleaved and Korean pine forest in northeast China

To assess phosphorus (P) status of forest soil under naturally restored vegetation,P fractions in the 10-cm soil layer were quantified at different successional stages on the clear-cut site of mixed broadleaved and Korean pine forest.Four communities of shrub,softwood broad-leaved forest,softwood and hardwood broad-leaved forest,and hardwood broad-leaved forest represented different succes-sional stages.A soil sample from a primary broad-leaved and Korean pine stand was the control.A sequential P frac-tionation scheme extracted empirically defined pools of P and path analysis used to partition the direct and indirect contribution of soil P fractions to available P.The results show that available P increased significantly with long-term succession,while both sodium bicarbonate-extractable P(NaHCO3-P) and sodium hydroxide-extractable P (NaOH-P) fractions were reduced in early successional stages and increased in late stages.Compared to the primary forest,concentrations of P fractions in the four stages signifi-cantly decreased except for HCl-P,indicating that soil P supplements over the long-term did not return to primary forest levels.The results of related analysis also showed that NaHCO3-Pi levels were significantly related to avail-able phosphorus.According to the path analysis coeffi-cient,NaHCO3-Pi exhibited the highest effect on available P among eight P fractions;the indirect effects of other P fractions via NaHCO3-Pi were larger than those with other P fractions.Overall,this study suggests that soil P bioavail-ability gradually improved during natural vegetation res-toration on clear-cut sites mainly through the increase of NaHCO3-P,where phosphorous is immediately available,and subsequently available phosphorus NaOH-P.     

Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.