Fast and Inexpensive Detection of Total and Extractable Element Concentrations in Aquatic Sediments Using Near-Infrared Reflectance Spectroscopy (NIRS)

Adequate biogeochemical characterization and monitoring of aquatic ecosystems, both for scientific purposes and for water management, pose high demands on spatial and temporal replication of chemical analyses. Near-infrared reflectance spectroscopy (NIRS) may offer a rapid, low-cost and reproducible alternative to standard analytical sample processing (digestion or extraction) and measuring techniques used for the chemical characterization of aquatic sediments. We analyzed a total of 191 sediment samples for total and NaCl-extractable concentrations of Al, Ca, Fe, K, Mg, Mn, N, Na, P, S, Si, and Zn as well as oxalate- extractable concentrations of Al, Fe, Mn and P. Based on the NIR spectral data and the reference values, calibration models for the prediction of element concentrations in unknown samples were developed and tested with an external validation procedure. Except Mn, all prediction models of total element concentrations were found to be acceptable to excellent (ratio of performance deviation: RPD 1.8–3.1). For extractable element fractions, viable model precision could be achieved for NaCl-extractable Ca, K, Mg, NH₄ ⁺-N, S and Si (RPD 1.7–2.2) and oxalate-extractable Al, Fe and P (RPD 1.9–2.3). For those elements that showed maximum total values below 3 g kg⁻¹ prediction models were found to become increasingly critical (RPD <2.0). Low concentrations also limited the performance of NIRS calibrations for extracted elements, with critical concentration thresholds <0.1 g kg⁻¹ and 3.3 g kg⁻¹ for NaCl and oxalate extractions, respectively. Thus, reliable NIRS measurements of trace metals are restricted to sediments with high metal content. Nevertheless, we demonstrated the suitability of NIRS measurements to determine a large array of chemical properties of aquatic sediments. The results indicate great potential of this fast technique as an analytical tool to better understand the large spatial and temporal variation of sediment characteristics in an economically viable way.     

Detecting and quantifying meat meal or meat and bone meal contamination in fishmeal by visible and near infrared reflectance spectra

The use of animal protein feeds such as meat meal or meat and bone meal (MMBM) play an important role in the feed manufacturing industry, but their safe and healthy use in animal feeds is of public concern in order to prevent the spread of bovine spongiform encephalopathy (BSE). The objective of the present work was to develop a technique using near infrared reflectance spectroscopy (NIRS) that would be suitable for detecting and quantifying contaminating levels of MMBM in fishmeal. To this end, a partial least squares (PLS) discriminant analysis and a modified partial least squares (MPLS) quantitative analysis, using visible and NIRS, were developed using a calibration set of 186 samples including 90 samples of pure fishmeal and 96 samples adulterated with MMBM at levels ranging from 10 to 320 g/kg. An external validation set, comprised of 39 pure samples and 54 adulterated samples, was used to validate the calibration model. A PLS discriminant analysis model developed with mathematic pretreatment 1,4,4,1, successfully detected fishmeal adulterated with MMBM. External validation indicated that all samples were discriminated correctly. A MPLS quantitative model, developed with mathematic pretreatment 1,4,4,1, also successfully predicted the MMBM in fishmeal with standard error of cross-validation (SECV) of 27.89 g/kg and ratio of the standard deviation of the validation set to the standard error of prediction (RPD) of 3.37. The calibration and validation results confirm that NIRS could provide the feed industry and inspection bodies with a rapid, non-destructive and non-invasive technique for the detection and quantification of MMBM in fishmeal.     

The prediction of intake potential and organic matter digestibility of grass silages by near infrared spectroscopy analysis of undried samples

A study was undertaken to examine a range of sample preparation and near infrared reflectance spectroscopy (NIRS) methodologies, using undried samples, for predicting organic matter digestibility (OMD g kg⁻¹) and ad libitum intake (g kg⁻¹ W^0.75) of grass silages. A total of eight sample preparation/NIRS scanning methods were examined involving three extents of silage comminution, two liquid extracts and scanning via either external probe (1100-2200 nm) or internal cell (1100-2500 nm). The spectral data (log 1/R) for each of eight methods were examined by three regression techniques each with a range of data transformations. The 136 silages used in the study were obtained from farms across Northern Ireland, over a two year period, and had in vivo OMD (sheep) and ad libitum intake (cattle) determined under uniform conditions. In the comparisons of the eight sample preparation/scanning methods, and the differing mathematical treatments of the spectral data, the sample population was divided into calibration (n = 91) and validation (n = 45) sets. The standard error of performance (SEP) on the validation set was used in comparisons of prediction accuracy. Across all 8 sample preparation/scanning methods, the modified partial least squares (MPLS) technique, generally minimized SEP's for both OMD and intake. The accuracy of prediction also increased with degree of comminution of the forage and with scanning by internal cell rather than external probe. The system providing the lowest SEP used the MPLS regression technique on spectra from the finely milled material scanned through the internal cell. This resulted in SEP and R² (variance accounted for in validation set) values of 24 (g/kg OM) and 0.88 (OMD) and 5.37 (g/kg W^0.75) and 0.77 (intake) respectively. These data indicate that with appropriate techniques NIRS scanning of undried samples of grass silage can produce predictions of intake and digestibility with accuracies similar to those achieved previously using NIRS with dried samples.     

镁肥对马尾松幼苗生长与叶片元素积累的影响

为了探讨上杭种源马尾松Pinus massoniana叶营养与生长对不同镁肥水平的响应,以其优良种源1年生苗为材料,设置4个镁肥梯度(42 g·m-2、85 g·m-2、170 g·m-2、339 g·m-2),测定移栽1年后苗木生长指标及叶内营养含量。结果表明,施镁能够促进元素P、K、Ca、Fe、Cu、Zn积累,抑制N、Mg、Mn积累;镁施肥量为85 g·m-2时,对N、Mg、Mn积累的抑制作用不显著,对P、K、Ca、Fe、Cu、Zn积累的促进作用最大,苗木生长最好,为最佳施肥量。施镁并不能促进苗木对镁的吸收,而是改变了营养供应的土壤环境,从而改变植物对其他营养的吸收比例,进而影响植物的生长。苗木的生长与Fe、P、K的关系最为密切,其次是Mg、Mn、Ca、N、Cu、Zn。     

The Element Contents of Platycladus orientalis plantation in Beijing

Carbon is the most abundant element in the organs of the edificator-31 years old Platy- cladus orientalis. High content of Ca occurred in the edificator, there are plenty of N. K. Mg as well with relatively low content of P and high content of Fe. The concentration of elements is greater in leaves than int woody tissues of tree and shrub. The element accumulation in the aboveground part was higher than those in the under ground part of the tree layer, 51 percent of C was accumulated in trunks. The largest percentage of other elements was accumulated by leaves. On the contrary, in tile tree layer the element accumulation in the under ground part was larger than those in the aboveground part of the shrub layer except N accumulation. The element accumulation in the plantation reached 17,000 kg/ha for C, 400 kg/ha for Ca, 104 kg/ha for N, 87 kg/ha for K, 30 kg/ha for Mg, 11–16 kg/ha for Al, P and Fe, 2.5 kg/ha for Na, 1 kg/ha for Mn, Cu and Zn. The retention of C in the plantation was the highest among the elements. The retention in the Tree layer decreased from Ca to N. K. The retention of N in shrub layer is greater than that of Ca. The element retentions in the plantation were 2700 kg/ha, a for C, 70 kg/ ha.a for Ca. 15–20 kg/ha.a for N, K, 2-5 kg/ha, for P, Fe, Al, and Mg, 1 kg/ha.a for the others. The nutrient pool in soil showed C>Ca>N>Fe>Mg>K>P>Na >Al, Mn>Cu>Zn in order. In the same soil condition, the element enrichment factors by various plants were quite different. Usually the enrichment factors of the shrub were greater than those of the tree. The following sequence of the requirment of nutrients by plantation was shown: C> Ca>N >K>Mg >Fe>P>AI>Na>Mn >Cu> Zn.     

Comparison of Trace Elements in the Scalp Hair of Malignant and Benign Breast Lesions Versus Healthy Women

Trace elements including Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were analyzed in the scalp hair samples of women with malignant breast lesions, women with benign breast lesions, and healthy donors using atomic absorption spectrophotometric method. In the scalp hair of malignant-tumor patients, the highest average concentration was shown by Ca (1,187 μg/g), followed by Na (655 μg/g), Mg (478 μg/g), Zn (391 μg/g), Sr (152 μg/g), Fe (114 μg/g), and K (89.8), while in the case of benign-tumor patients, the average estimated element levels were 1,522, 1,093, 572, 457, 217, 80.4, and 74.7 μg/g, respectively. Most of the elements exhibited non-normal distribution evidenced by large spread, standard error, and skewness values. Mean concentrations of Ca (634 μg/g), Zn (206 μg/g), Mg (162 μg/g), Fe (129 μg/g), and Na (82.1 μg/g) were noteworthy in the scalp hair of healthy women. Average levels of Na, Sr, K, Cd, Co, Pb, Mg, Ca, Zn, Ni, Sb, and Mn were revealed to be significantly higher in the hair of malignant and benign patients compared to the healthy women; however, Fe, Cu, Al, and Cr were not significantly different in the scalp hair of the three groups. The quartile distributions of Ca, Cd, Co, Cr, K, Mg, Mn, Na, Ni, Pb, Sb, and Sr revealed maximum spread in the scalp hair of malignant and benign groups; nevertheless, Al, Cu, Fe, and Zn exhibited almost comparable quartile levels in the three groups. Strong correlation coefficients were found between Fe and Cd, Al and Na, Mn and Sr, Co and Cr, Cd and Cr, Pb and K, Pb and Mn, Cu and Na, and Al and Fe in the scalp hair of malignant-tumor patients, while Fe and K, Cd and Co, Na and Co, and Cr and Pb showed strong correlations in the scalp hair of benign-tumor patients, both of which were significantly different compared with the healthy subjects. Multivariate cluster analysis also revealed divergent clustering of the elements in the scalp hair of malignant and benign patients in comparison with the healthy women.     

The Effect of Age on 12 Chemical Element Contents in the Intact Prostate of Adult Men Investigated by Inductively Coupled Plasma Atomic Emission Spectrometry

The effect of age on 12 chemical element contents in intact prostate of 64 apparently healthy, 13-60-year-old men (mean age 36.5 years) was investigated by inductively coupled plasma atomic emission spectrometry. Mean values (M ± SΕΜ) for mass fraction (milligrams/kilogram, on dry weight basis) of Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, and Zn were: Ba 1.18 ± 0.12, Ca 2,178 ± 160, Cu 10.7 ± 0.9, Fe 122 ± 5, K 12,530 ± 360, Mg 1,100 ± 70, Na 10,470 ± 320, P 7,580 ± 300, S 8,720 ± 180, Sr 1.85 ± 0.28, and Zn 782 ± 97, respectively. The upper limit of mean content of V was ≤0.22 mg/kg. A tendency of age-related increase in Ca, Fe, Na, and Zn mass fraction as well an increase in Zn/Ba, Zn/Ca, Zn/Cu, Zn/Fe, Zn/K, Zn/Mg, Zn/Na, Zn/P, Zn/S, and Zn/Sr ratios in prostate was observed. A significant positive correlation was seen between the prostatic zinc and Ca, Cu, Fe, Mg, Na, and P contents.     

近红外光谱分析法测定东北黑土有机碳和全氮含量

以我国东北黑土为研究对象,分析了2004-2005年采集的136个土壤样品在3699～12000 cm^-1范围的近红外光谱,利用偏最小二乘法建立了原始光谱吸光度与土壤有机碳、全氮和碳氮比之间的定量分析模型.结果表明：土壤有机碳和全氮的模型拟合效果良好,决定系数R²分别为0.92和0.91（P<0.001）,相对分析误差RPD分别为3.45和3.36,利用该模型对验证样本土壤有机碳和全氮的预测值与实测值之间的相关系数分别为0.94和0.93（P<0.001）,表明可以用近红外光谱分析法对黑土有机碳和全氮含量进行测定.但是利用近红外光谱分析法对土壤碳氮比的预测并不理想,虽然验证样本集黑土碳氮比模型预测值与实测值呈显著相关（r＝0.74,P<0.001）,但是校正模型的R²为0.61,RPD仅为1.61,建立的模型不能对黑土碳氮比做出合理的估测.     

鸡内金中氨基酸及营养元素含量的测定

采用日立 835 - 5 0型氨基酸自动分析仪和岛津Z - 80 0 0型原子吸收分光光计。测定了鸡内金中氨基酸和营养元素的含量 ,结果表明 :鸡内金中营养元素钾、钙、镁、铜、锌、铁、锰含量分别为 36 9.5 0、12 0 .5 6、470 .77、31.89、32 .42、5 5 9.6 4、8.11mg/kg ;氨基酸总量为 86 .92 4% ,必需氨基酸占氨基酸总量的 30 .2 6 4%。     

ICP-AES analysis in sesame on the root rot disease incidence

Five different sesame varieties namely CO-1, VRI-1, VRI-2, TMV-3 and TMV-4 are grown in different trial plots with three treatments viz., control (T₁), chemical fertiliser (T₂) and organic manure (T₃). Diseased and healthy roots are collected fieldwide using standard procedures. Roots are subjected to ICP-AES analysis and the elemental status of the diseased and healthy roots are estimated. A correlation between the elements (Ca, K, Na, Mg, Fe, Cu, Zn) of healthy and diseased plants with reference to manure treatment and different varieties has been attempted. It could be suggested that lowering the concentration of Ca, Na, Mg and Fe and increasing the concentration of K, Cu and Zn in the soil with T₃ treatment may very much reduce root rot disease occurrence.     

Interaction between VA-mycorrhizal fungus and Azotobacter and their combined effects on growth of tall fescue

Amounts of N, P, K, Ca, Mg, Zn, Fe, and Mn absorbed by a nodulating and a non-nodulating (Non-nod) peanut genotype at two nitrogen fertilizer levels (nil and 200 kg N ha^–1) were determined in a field experiment. The amounts of nutrient elements in the plant parts were greatest for N, followed by K, Ca, Mg, P, Fe, Mn, and Zn in descending order. Although there were differences in the uptake of other nutrients, the major difference between Non-nod and nodulating genotypes was in nitrogen indicating the poor yield of the Non-nod line due to its inability to acquire N.Submitted as Journal Article No: 677 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Leaf-litter and changing nutrient levels in a seasonally dry tropical hardwood forest,Belize, C.A.

Summary Total above ground plant biomass in a 45 year old seasonally dry tropical hardwood forest was estimated to be approximately 56,000 kg/ha oven dry weight. Nutrients immobilized in the standing vegetation were: N, 203 kg/ha; P, 24 kg/ha; K, 234 kg/ha; Ca, 195 kg/ha; Mg, 47 kg/ha; Na, 9 kg/ha; Mn, 1 kg/ha; Cu, 0.5 kg/ha; Zn, 3 kg/ha; Fe, 4 kg/ha. Total nutrients returned each year through the litter were: N, 156 kg/ha; P, 9 kg/ha; K, 59 kg/ha; Ca, 373 kg/ha; Mg, 32 kg/ha; Na, 5 kg/ha; Mn, 1 kg/ha; Al, 21 kg/ha; Zn, 0.3 kg/ha; Fe, 9 kg/ha. Half of the nutrients immobilized in the standing vegetation were found in the leaves and are returned annually to the soil. Although litter fall is interrupted during the year, the mean nutrient content of the litter was high –5.2%.A decomposition rate of 0.48 percent per day was considered high for a seasonally dry tropical hardwood forest. Fluctuations in soil nutrient levels showed a sharp increase at the start of the rainy season. Later during the dry season nutrient levels decreased to concentrations similar to what they were just prior to the rainy season. Soil organic matter levels were very high –20% in the top 12 cm.     

Mineral and trace element composition of the roe and muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) with respect to nutrient requirements: Elements in rainbow trout products

BackgroundDue to excellent nutritional properties of fish and fish products, dietitians recommend their larger share in the diet, for both the prevention and treatment of diet-related diseases. In this context particular attention should be given to fish eggs (roe). The aim of the study was to compare the content of selected minerals and trace elements in the roe and muscle tissue of aquaculture-reared rainbow trout. Moreover, the extent to which an edible portion of 100 g of fish product (roe or fillet) satisfies the requirements for these elements in adult consumers (women and men) and children was determined.MethodsThe research material was represented by 20 farmed rainbow trout females (Oncorhynchus mykiss). In muscle tissue and roe the proximate composition, energy value, and nutritional quality index were examined. Concentrations of K, Na, Ca, Mg, Zn, Fe, Mn and Cu were determined by flame atomic absorption spectrometry analysis. The levels of minerals and trace elements in fish products were used to calculate the percentages of the recommended dietary reference values for adults and children in portion of 100 g.ResultsThe roe had higher content of 7 elements including, Zn (29.40 ± 1.38, 27.74–30.91 mg/kg), Mn (1.66 ± 0.08, 1.55–1.73 mg/kg), Fe (11.17 ± 0.35, 10.75–11.60 mg/kg), Cu (1.24 ± 0.04, 1.21–1.30 mg/kg), Ca (546.90 ± 23.68, 522.02–578.96 mg/kg), Mg (546.97 ± 23.68, 522.02–578.96 mg/kg), Na (403.61 ± 5.53, 397.29–407.57 mg/kg) compared to muscle tissue, respectively, Zn (2.73 ± 0.97, 0.94–3.77 mg/kg, Mn (0.22 ± 0.10, 0.14–0.46 mg/kg), Fe (2.19 ± 1.44, 1.02–5.50 mg/kg), Cu (0.24 ± 0.06, 0.17–0.36 mg/kg), Ca (164.07 ± 71.72, 93.24–306.32 mg/kg), Mg (240.00 ± 73.37, 127.92–316.41 mg/kg), Na (273.37 ± 99.65, 183.93–524.41 mg/kg). In turn, the muscle tissue contained 3 times as much K (5159.87 ± 974.70, 4004.63–6343.91 mg/kg) as the roe (1713.65 ± 58.68, 1643.97–1764.14 mg/kg). The roe covered the recommended nutrition standards (population reference intake, PRI and adequate intake, AI) to a greater extent than the fillet for all analysed trace elements and minerals except K. For children, the contribution of roe to the reference intake of such elements as Mg, Zn, Fe, Mn and Cu was particularly high. Therefore the roe should be considered as a source of Mg for all consumer groups, and as high in Zn for women and children. The suggested portion of fillet and roe provided only 2–3 % of the daily requirement for Na.ConclusionsDespite the differences found, both roe and fillet from rainbow trout are a good source of analysed elements. The results indicate the need to continue research in order to determine the influence of other factors on the content of minerals and trace elements in roe and the possibility of using gonads to enrich other food products with elements.     

Assessing near-infrared reflectance spectroscopy for the rapid detection of lipid and biomass in microalgae cultures

With intensification of interest in microalgae as a source of biomass for biofuel production, rapid methods are needed for lipid screening of cultures. In this study, near-infrared reflectance spectroscopy (NIRS) was assessed as a method for analysing lipid (specifically, total fatty acid methyl esters (FAME) obtainable from processing) and biomass in late logarithmic and stationary phase cultures of the green alga Kirchneriella sp. and the eustigmatophyte Nannochloropsis sp. Culture samples were filtered, scanned by NIRS and chemically analysed; by combining these sets of information, models were developed to predict total biomass, FAME content and FAME as a percentage of dry weight in samples. Chemically derived (actual) and NIRS-predicted data were compared using the coefficient of determination (R ²) and the ratio of the standard deviation (SD) of actual data to the SD of NIRS prediction (RPD). For Kirchneriella sp. samples, models gave excellent prediction (R ²?≥?0.96; RPD?≥?4.8) for all parameters. For Nannochloropsis sp., the model metrics were less favourable (R ²?=?0.84–0.94; RPD?=?2.5–4.2), though sufficient to provide estimations that could be useful for screening purposes. This technique may require further validation and comparison with other species, but this study shows the potential of the NIRS as a rapid screening method (e.g. up to 200 sample analyses per day) for estimating FAME or other microalgal constituents and encourages further investigation.     

湘西地区木通果实微量元素的测定

采用马弗炉干法灰化消化样品,火馅原子吸收法连续测定白木通Akebia trifoliata var.australis (Cieli._Kehd、三叶木通A.trifoliata(Thumb.)Koidz、木通A.quinata Decne.果实中微量金属元素,检测出K,Ca,Na,Mg,Fe,Zn,Mn,Cu等8种元素含量。3种植物果实中K,Ca,Mg含量较高(＞0．1000mg/g),其中K元素远高于其他元素,Na,Cu含量较低(＜0．0100mg/g)。Fe,Zn,Mn的含量处于中等水平。白木通果实中K,Me,Zn,Mn 4种矿质元素高于三叶木通和木通。木通果实中Ca,Fe两种元素稍高于白木通、三叶木通。Na,Cu两种微量元素在3种果实中含量基本相拟。     

Investigation of Trace Element Content in the Seeds,Pulp, and Peel of Mashui Oranges Using Microwave Digestion and ICP-MS Analysis

Fresh Mashui orange samples were pretreated with microwave digestion using an HNO₃-H₂O₂ system. The levels of Mg, K, Ca, Fe, Mn, Cu, Zn, As, Cd, and Pb in the seeds, pulp, and peel were then determined using inductively coupled plasma mass spectrometry (ICP-MS) combined with collision cell technology (CCT) and kinetic energy discrimination (KED). The standard curve coefficient of determinations of the ten tested elements were between 0.9995 and 0.9999. The instrument detection limit was between 0.112 ng/L and 3.05 ng/mL. The method detection limit was between 0.0281 and 763 ng/g. The average recovery rate was between 85.0 and 117%. The current results showed that Mashui oranges are rich in three elements, namely Mg, K, and Ca. The concentrations of K and Ca were significantly higher than that of Mg in the peel. The content of K was the highest in the seeds. Fe, Mn, Cu, and Zn had the second highest concentrations, and Fe was the highest in the seeds, while Cu was the lowest in the peel. As, Cd, and Pb (hazardous elements) had the lowest concentrations of all the tested elements.     

NIRS prediction of the feed value of temperate forages: efficacy of four calibration strategies

Near infrared reflectance spectroscopy (NIRS) of 924 fresh temperate forages were used to develop calibration models for chemical composition - crude ash (CA) and crude protein (CP) - organic matter digestibility (OMD) and voluntary intake (VI). We used 110 samples to assess the models. Four calibration strategies for determining forage quality were compared: (i) species-specific calibration, (ii) family-specific calibration, (iii) a global procedure and (iv) a local approach. Forage calibration data sets displayed CA values ranging from 52 to 205 g/kg of dry matter (DM), CP values from 50 to 280 g/kg DM, OMD values from 0.48 to 0.85 g/g and VI values from 22.5 to 115.2 g DM/kg metabolic body weight (BW0.75). The calibration models performed well for all the variables except for VI. For CA, local procedure showed lower standard error of prediction (SEP) than species-specific, family-specific or global models. For CP, the calibration models all showed similar SEP values (11.13, 11.08, 11.38 and 11.34 g/kg DM for species-specific, family-specific, global and local approaches). For OMD, the local procedure gave a similar SEP (0.024 g/g) to specific species and global procedures (0.027 g/g) and a lower SEP than the family-specific approach (0.028 g/g). For VI, the local approach and species-specific calibration showed lower SEP (7.08 and 7.16 g/kg BW0.75) than the broad-based calibrations (8.09 and 8.34 g/kg BW0.75 for family-specific model and global procedure, respectively). Local calibration may thus offer a practical way to develop robust universal equations for animal response determinations.     

滇池水-植物系统金属元素的分布特征和相关性研究

对滇池优势水生植物凤眼莲、旱生莲子草、红线草、聚草和茭草及其对应水环境中的Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ｆｅ、Ｍｎ、Ｚｎ、Ｃｕ、Ｐｂ、Ｃｄ进行了化学分析,初步揭示了滇池水－植物系统金属元素的分布特征和关性。结果表明,滇池水域属Ｋ、Ｃａ、Ｍｇ、Ｆｅ高背景生物地球化学区,植物体内金属元素的含量,既与植物种属特性有关,又明显地受环境因素的影响,植物对营养元素的吸收不一定与环境中相应元素的浓度呈简单的线性关系,而     

Nutrition of Captive Cheetahs: Food Composition and Blood Parameters

Diet and nutrition of cheetahs was evaluated through survey, in conjunction with chemical analysis of feed and plasma samples, as part of a multidisciplinary effort to investigate underlying causes of low reproductive success in North American captive cheetah populations. Cheetahs consumed an average of 1.32 ± 0.4 kg of food daily, containing approximately 1,800 kcal, and maintained an average body mass of 36.7 ± 1.0 kg (n = 34). A commercially prepared horsemeat-based mixture comprised the dietary staple in 10 of 13 zoos responding to the survey, with additional whole or carcass portions offered 1--2 days per week to maintain variety and provide periodontal stimulation. Seven of 13 respondents fasted animals 1 day/week; five maintained no fast days. The primary meat product (n = 14 samples) contained: 58% crude protein, 28% crude fat, 7% total ash, 52 Iu/kg vitamin E, 9.7 Iu/g vitamin A, and 2,200 mg/kg taurine (dry basis). Mineral content of the same food item was: 1.9% Ca, 10.0 mg/kg Cu, 645.2 mg/kg Fe, 0.08% Mg, 22.6 mg/kg Mn, 1.3% P, 0.4% Na, and 127.8 mg/kg Zn. Nutrient levels, except vitamin E (and possibly Mg), met or exceeded recommendations established for domestic felids. Plasma α-tocopherol, retinol, and taurine (18.1, 1.82, 128.4 μmol/L, respectively) concentrations were similar to normals for domestic felids, as were mean plasma mineral levels (n = 81; in mEq/L: 5.64 (Ca), 0.03 (Cu), 0.03 (Fe), 2.0 (Mg), 166.0 (Na), 12.3 (P), and 0.026 (Zn)). No gross physiological or dietary nutrient imbalances were evident from this survey. © 1993 Wiley-Liss, Inc.     

Under-storey Nutrient Content in an Age Sequence of Douglas-fir Stands

The nutrient concentrations and contents of the under-storeyspecies were estimated for a series of Pacific North-west Douglas-fir[Pseudotsuga menxiessii (Mirb.) Franco] stands ranging in agefrom 9 to 95 years. Analyses were carried out for ash, N, P,K, Ca, Mg, Mn, Fe, Zn and Na and significant differences innutrient concentrations were found to exist between species;species rejecting certain nutrients and accumulating others.General trends for mean concentrations of some nutrients areassociated with stand maturity in that ash, K and Mg decline,P and Mn increase and N and Ca reaches a peak at 20–30years and then declines. The nutrient contents (kg ha^–1)of the under-storey component of the stands are presented andtrends discussed. Mineral nutrient content, under-storey vegetation, Pseudotsuga menziessii stands, Douglas-fir