Global Expanded Nutrient Supply (GENuS) Model: A New Method for Estimating the Global Dietary Supply of Nutrients

Insufficient data exist for accurate estimation of global nutrient supplies. Commonly used global datasets contain key weaknesses: 1) data with global coverage, such as the FAO food balance sheets, lack specific information about many individual foods and no information on micronutrient supplies nor heterogeneity among subnational populations, while 2) household surveys provide a closer approximation of consumption, but are often not nationally representative, do not commonly capture many foods consumed outside of the home, and only provide adequate information for a few select populations. Here, we attempt to improve upon these datasets by constructing a new model—the Global Expanded Nutrient Supply (GENuS) model—to estimate nutrient availabilities for 23 individual nutrients across 225 food categories for thirty-four age-sex groups in nearly all countries. Furthermore, the model provides historical trends in dietary nutritional supplies at the national level using data from 1961–2011. We determine supplies of edible food by expanding the food balance sheet data using FAO production and trade data to increase food supply estimates from 98 to 221 food groups, and then estimate the proportion of major cereals being processed to flours to increase to 225. Next, we estimate intake among twenty-six demographic groups (ages 20+, both sexes) in each country by using data taken from the Global Dietary Database, which uses nationally representative surveys to relate national averages of food consumption to individual age and sex-groups; for children and adolescents where GDD data does not yet exist, average calorie-adjusted amounts are assumed. Finally, we match food supplies with nutrient densities from regional food composition tables to estimate nutrient supplies, running Monte Carlo simulations to find the range of potential nutrient supplies provided by the diet. To validate our new method, we compare the GENuS estimates of nutrient supplies against independent estimates by the USDA for historical US nutrition and find very good agreement for 21 of 23 nutrients, though sodium and dietary fiber will require further improvement.     

Human Exposure to Arsenic,Cadmium, Mercury,and Lead from Foods in Catalonia,Spain: Temporal Trend

The main purpose of this study was to establish the temporal trend in the daily dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) by the population of Catalonia, Spain. Concentrations of these elements were determined in samples of a number of food items widely consumed in that country. The dietary intake of As, Cd, Hg, and Pb was then estimated for various age–gender groups of population: children, adolescents, adults, and seniors. In the present study, the dietary intakes of As, inorganic As, Cd, Hg, methylmercury, and Pb were 328.37, 16.22, 19.47, 11.39, 10.25, and 101.47 μg/day, respectively, while in a previous (2006) survey, the dietary intakes of As, inorganic As, Cd, Hg, methylmercury, and Pb were 261.01, 33.17, 9.80, 12.61, 11.35, and 45.13 μg/day, respectively. The estimated intakes of Cd, Hg, and Pb are still notably lower than the respective PTWIs, while that of inorganic As is also lower than its BMDL₀₁. In summary, the results of this study indicate that, currently, the dietary intakes of As, Cd, Hg, and Pb should not mean additional health risks for the consumers.     

Estimating the Global Prevalence of Inadequate Zinc Intake from National Food Balance Sheets: Effects of Methodological Assumptions

Background

The prevalence of inadequate zinc intake in a population can be estimated by comparing the zinc content of the food supply with the population’s theoretical requirement for zinc. However, assumptions regarding the nutrient composition of foods, zinc requirements, and zinc absorption may affect prevalence estimates. These analyses were conducted to: (1) evaluate the effect of varying methodological assumptions on country-specific estimates of the prevalence of dietary zinc inadequacy and (2) generate a model considered to provide the best estimates.

Methodology and Principal Findings

National food balance data were obtained from the Food and Agriculture Organization of the United Nations. Zinc and phytate contents of these foods were estimated from three nutrient composition databases. Zinc absorption was predicted using a mathematical model (Miller equation). Theoretical mean daily per capita physiological and dietary requirements for zinc were calculated using recommendations from the Food and Nutrition Board of the Institute of Medicine and the International Zinc Nutrition Consultative Group. The estimated global prevalence of inadequate zinc intake varied between 12–66%, depending on which methodological assumptions were applied. However, country-specific rank order of the estimated prevalence of inadequate intake was conserved across all models (r = 0.57–0.99, P<0.01). A “best-estimate” model, comprised of zinc and phytate data from a composite nutrient database and IZiNCG physiological requirements for absorbed zinc, estimated the global prevalence of inadequate zinc intake to be 17.3%.

Conclusions and Significance

Given the multiple sources of uncertainty in this method, caution must be taken in the interpretation of the estimated prevalence figures. However, the results of all models indicate that inadequate zinc intake may be fairly common globally. Inferences regarding the relative likelihood of zinc deficiency as a public health problem in different countries can be drawn based on the country-specific rank order of estimated prevalence of inadequate zinc intake.     

Dietary boron intakes of selected populations in the United States

Knowledge of daily boron (B) intakes will assist researchers in establishing B requirements and elucidating the metabolic role of B in humans. B concentrations in commonly consumed foods were utilized to approximate the B intake of selected US populations. Triplicate food samples were digested at low temperatures with 16M HNO₃ and 30% H₂O₂, and analyzed by inductively coupled plasma spectroscopy (ICP). Milk and dairy products, juices, and beverages were the largest contributors to dietary B. Total B content of average daily diets ranged from 548 μg for toddlers (2 yr old) to 883 μg for mature males (60–65 yr old), excluding tap water contributions. Toddlers consumed 3.7 times more B than mature males when adjusted for body weight (body wt) and consumed the diet with the highest boron density (1.8 μg/kJ or 0.43 μg/kcal). Adolescent females consumed a diet with the lowest B density (1.12 μg/kJ or 0.26 μg/kcal). Food B concentrations applied to diet records (1020 μg/d) and ICP analysis of the corresponding food composites (1170 μg/d) were comparable (p < 0.05). Current estimations of B in US diets are consistent with reports in the literature stating that normal adult daily B intakes are approx 1 mg. Presented at the symposium “Second International Symposium on the Health Effects of Boron and Its Compounds” held in Irvine, CA, on October 23, 1997. This symposium was presented by the University of California, Irvine. The publication of the symposium was supported by U.S. Borax Inc. Guest editors for this symposium were B. Dwight Culver (University of California, Irvine, CA) and James R. Coughlin (Coughlin and Associates, Newport Coast, CA). US Department of Agriculture, Agricultural Research Service, Northern Plains Area is an equal opportunity/affirmative action employer, and all agency services are available without discrimination.     

Dietary Intake of Arsenic, Cadmium, Mercury, and Lead by the Population of Catalonia, Spain

The concentrations of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) were determined in samples of food items widely consumed by the population of Catalonia, Spain. All samples were randomly acquired in 12 cities of Catalonia between March and June of 2006 and analyzed by inductively coupled plasma mass spectrometry. The dietary intake of these elements was estimated for various age–gender groups of population: children, adolescents, adults, and seniors. In order to determine the temporal trend on the dietary exposure to As, Cd, Hg, and Pb, the current results were compared with those of a previous survey (2000). In the present market basket study, for a standard male adult of 70-kg body weight living in Catalonia, the dietary intakes of As, Cd, Hg, and Pb were 261.01, 9.80, 12.61, and 45.13 μg/day, respectively, while in the 2000 survey, these intakes were 223.59, 15.73, 21.22, and 28.37 μg/day, for As, Cd, Hg, and Pb, respectively. For As, the only food groups currently contributing with measurable amounts to intake of total As were fish and shellfish and cereals, while for Cd the highest contribution to total intake corresponded to pulses, tubers, and cereals. For Hg, the contribution was only due to fish and shellfish, while cereals were the group with the highest contribution to total Pb intake. The estimated intakes of As, Cd, Hg, and Pb are notably lower than the respective provisional tolerable weekly intakes, which indicate that these intakes should not mean additional health risks for the consumers.     

Fumonisin intake of the German consumer

In order to calculate the dietary fumonisin intake of the German consumer, a large survey was carried out on a variety of potentially contaminated products in the period between December 1998 and July 2001. A total of 1960 food samples comprising all known relevant groups of products were analysed for fumonisins. Furthermore, 272 of these samples were also analysed for hydrolysed fumonisins (HFB). For routine analysis enzyme immunoassay was used, confirmatory and control analyses were performed using HPLC-FLD after precolumn derivatisation, or by LC-MS/MS. Daily intake of fumonisins was calculated by combining fumonisin contamination data obtained in this study with available food consumption data for Germany. In a “mean case” scenario, median fumonisin levels in foods and mean food intake values were used. To generate a “bad case” scenario, the 90^th percentile of fumonisin levels in foods and mean food intake values were combined. The overall daily fumonisin intake by the German consumer was 1.1 μg in the “mean case” scenario, and 21 μg in the “bad case” scenario. It was concluded that in general there is no increased risk for the German consumer in aspects of exceeding the recommended tolerable daily intake of fumonisins (2 μg/kg body weight). However, certain products (and certain brands of products) were repeatedly found to contain elevated fumonisin levels, which in a “worst case” scenario (“high” food intake of maize-based products) could pose a potential risk for the consumer, in particular concerning foods for infants and young children. High fumonisin levels were found in infant foods in 1999, but contamination levels decreased strongly in the following years. HFBs (mostly HFB₁) were frequently found in processed cereals such as corn flakes, but in relatively low concentrations. According to our findings, the new European Union maximum levels for fumonisins are suitable to eliminate peak contamination levels of fumonisins in foods, but would lead to a regular excess of the TDI for infants and young children if these maximum levels would indeed be exhausted. Financial support: This work was financially supported by the German Federal Ministry for Nutrition, Agriculture and Consumer Protection, research grant 415-6080-1/60 (BMG alt).     

Zinc and copper intake and sources in healthy adults living in Bangkok and surrounding districts

The levels of intake and food sources of zinc and copper in 231 20–80 yr old healthy adults living in Bangkok and surrounding districts were determined. Dietary data from 3-d food records collected and validated at Research Center, Ramathibodi Hospital were analyzed. Levels of zinc and copper intake were compared between sexes and age groups (20–39, 40–59, and 60–80 yr). Mean daily zinc and copper intakes (±SEM) in men were 6.3 ±0.2 and 1.9 ±0.1 mg, respectively. Mean daily zinc and copper intakes (±SEM) estimated in women (5.5 ±0.2 and 1.6 +-0.1 mg) were significantly lower. Higher zinc and copper intakes were found in the younger (20-39 yr) age group of both sexes. This could be explained by higher density and percentage from animal source of both nutrients. Consumption of various types of meat, fish, egg, and milk accounted for 42 and 22%, and rice, the staple food of Thai people for 9 and 23% of total dietary zinc and copper, respectively.     

Estimation of Boron Intake and its Relation with Bone Mineral Density in Free-Living Korean Female Subjects

In this study, the status of boron intake was evaluated and its relation with bone mineral density was examined among free-living female subjects in Korea. Boron intake was estimated through the use of the database of boron content in frequently consumed foods by Korean people as well as measuring bone mineral density, taking anthropometric measurements, and surveying dietary intake of 134 adult females in order to relatively evaluate the intake of boron as a nutrient to supplement the low level of calcium intake and to verify its relationship with bone mineral density. Average age, height, and weight of the subjects were respectively 40.84 years, 157.62 cm and 59.70 kg. Also, average bone mineral density of lumbar spine L1–L4 and average bone mineral density of the femoral neck were 0.92 g/cm² and 0.80 g/cm², respectively. Their average intakes of energy and boron per day were 6,538.53 kJ and 926.94 μg. Intake of boron through vegetables, fruits, and cereals accounted for 61.72% of the overall boron intake. The food item that contributed most to their daily boron intake was rice. Also, 65.41% of overall boron intake was from 30 varieties of other food items, such as soybean paste, soybeans, red beans, watermelons, oriental melons, pears, Chinese cabbage Kimchi, soybean sprouts and soybean milk, etc. Boron intake did not show significant relation to bone mineral density in lumbar vertebra and femoral region. In summary, the average daily intake of boron was 926.94 μg and did not display significant relation to bone mineral density in 134 free-living female subjects. The continuous evaluation of boron consumption by more diverse targets will need to be conducted in the future.     

Intake of Inorganic Arsenic in the North American Diet

Dietary intake of inorganic arsenic, previously assumed to be an insignificant source of arsenic exposure in humans, was estimated for Canadian and United States populations. Input data included arsenic contents of various food groups, a limited historical database from the Ontario Ministry of the Environment measuring the percent inorganic arsenic in food groups, and food consumption data. Estimated daily dietary intake of inorganic arsenic ranges from 8.3 to 14?µg/day in the United States and from 4.8 to 12.7?µg/day in Canada for various age groups. These data suggest that between 21% to 40% of total dietary arsenic occurs in inorganic forms. Uncertainties regarding total arsenic in dairy products in the data set applied here may account for observed differences between United States and Canadian estimates. While estimates provided here are preliminary because of limitations in data on the proportion of inorganic arsenic in foods, this analysis suggests that dietary intake of inorganic arsenic is higher than is currently assumed. Additional research is needed to more fully characterize inorganic arsenic concentrations in foods. Future study is also needed on the variability of total and inorganic arsenic in foods and the bioavailability of dietary inorganic arsenic.     

Human exposure to metals through the diet in Tarragona, Spain

The concentrations of arsenic (As), beryllium (Be), cadmium (cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were determined in a number of food items purchased in zones of Tarragona, County (Catalonia, Spain) near a hazardous waste incinerator (HWI), which has been operating since 1999. Food samples corresponded to the following groups: meat, fish and seafood, pulses, cereals, vegetables, fruits, tubers, whole milk, yogurt, eggs, and sugar. Be and Tl were under their respective limits of detection in all samples. For the analyzed trace elements, the dietary intake by the general population of Tarragona was 458.5 μg/d for As, 14.3 μg/d for Cd, 88.3 μg/d for Cr, 5.3 μg/d for Hg, 2421.4 μg/d for Mn, 138.3 μg/d for Ni, 44.8 μg/d for Pb, 34.6 μg/d for Sn, and 28.9 μg/d for V. Results were compared with those found in a baseline survey carried out in the same area during the construction of the HWI (1996–1998). In general terms, the dietary intake of metals in 2003 was comparatively similar to those found in the baseline survey. For the most toxic elements (As, Cd, Hg, and Pb), it was under their respective Provisional Tolerable Weekly Intake (PTWI) estabished by the FAO/WHO.     

Determination of the daily selenium intake in slovakia

Three models were used to determine the daily dietary Selenium intake in Slovakia. The Selenium content of food produced and consumed in the Slovak Republic was used to estimate and calculate the daily Selenium intake based on food consumption data per capita and seven days, (24 h) eating protocol models. In a duplicate portion model, Selenium was analyzed in a whole day hospital diet during an eight-day period. According to these models the daily dietary Selenium intake was 38.2 μg; 43.3 ±6.5 μg for men and 32.6 ±6.6 μg for women; 27.1 ±7.8 μg for normal and 32.3 ±4.8 μg for nourishing hospital diets. The main contributors of Selenium to daily intake were the following: eggs, pork, and poultry. The obtained results indicate that the daily dietary intake of Selenium of the Slovak people is below the recommended values.     

Magnesium and methionine deprivation affect the response of rats to boron deprivation

A series of nine experiments were done to obtain further evidence that boron might be involved in major mineral metabolism (Ca, P, and Mg), thus indicating that boron is an essential nutrient for animals. Eight factorially arranged experiments of 6–10 wk durations were done with weanling Sprague-Dawley male rats. One factorially arranged experiment was done with weanling spontaneously hypertensive rats. The variables in each experiment were dietary boron supplements of 0 and 3 μg/g, and dietary magnesium supplements of either 200 (Experiments 1–3) or 100 (Experiments 4–9) and 400 μg/g. In Experiments 7 and 9, a third variable was dietary manganese supplements of 25 and 50 μg/g. Methionine status was varied throughout the series of experiments by supplementing the casein-based diet with methionine and arginine. Findings were obtained indicating that the severity of magnesium deprivation and the methionine status of the rat strongly influence the extent and nature of the interaction between magnesium and boron, and the response to boron deprivation. When magnesium deprivation was severe enough to cause typical signs of deficiency, a significant interaction between boron and magnesium was found. Generally, the interaction was characterized by the deprivation of one of the elements making the deficiency signs of the other more marked. The interaction was most evident when the diet was not supplemented with methionine and especially when the diet contained luxuriant arginine. Signs of boron deprivation were also more marked and consistent when the diet contained marginal methionine and luxuriant arginine. Among the signs of boron deprivation exhibited by rats fed marginal methionine were depressed growth and bone magnesium concentration, and elevated spleen wt/body wt and kidney wt/body wt ratios. Because the boron supplement of 3 μg/g did not make the dietary intake of this element unusual, it seems likely that the response of the rats to dietary boron in the present study were manifestations of physiological, not pharmacological, actions, and support the hypothesis that boron is an essential nutrient for the rat. Mentions of a trademark or proprietary product does not consitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Incidence and levels of fumonisin contamination in Colombian corn and corn products

A survey was conducted to determine the levels of fumonisins B1 and B2 in corn and corn-based products available in Colombia for human and animal consumption. A total of 120 samples were analyzed by acetonitrile-water extraction, cleanup with a strong-anion-exchange column, and liquid chromatography with o-phthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. The samples of corn and corn-based products for animal intake were taken at different feed manufacturing plants, whereas the samples used for human foods where purchased from local retail stores. The number of positive samples for fumonisin B1 was 20.0% higher in corn and corn-based products for animal intake (75.0%) than in corn and corn-based products for human consumption (55.0%). The levels of fumonisin B1 were also higher in corn and corn-based products for animal intake (mean = 694 μg/kg; range = 32–2964 μg/kg), than in corn and corn-based products for human intake (mean = 218 μg/kg; range = 24–2170 μg/ kg). The incidence and levels of fumonisin B2 were lower than those for fumonisin B1. Corn and corn-based products for animal consumption had an incidence of fumonisin B2 of 58.3%, with a mean value of 283 μg/kg, and a range of 44–987 μg/kg. The incidence of fumonisin B2 in corn-based products for human intake was 35.0%, with a mean value of 118 μg/kg and a range of 21–833 μg/kg. The highest incidence and levels of fumonisins were found in samples of hominy feed, with concentrations ranging from 86 to 2964 μg/kg fumonisin B1 and 57 to 987 μg/kg fumonisin B2.     

Atlantic Bluefin Tuna in the Gulf of Maine, I: Estimation of Seasonal Abundance Accounting for Movement, School and School-Aggregation Behaviour

Direct assessment of the abundance of highly migratory pelagic species, such as tuna, is rarely available and most indices are based on catch information. We estimate the seasonal abundance of North Atlantic bluefin tuna, Thunnus thynnus, in the Gulf of Maine (GOM) from a 3-year aerial survey conducted with commercial spotter pilots, while also utilizing findings from analyses of tracking and tagging data. We apply statistical correction and calibration to seasonal abundance estimates accounting for measured changes in horizontal and vertical movement behaviour, size, shape and aggregation of bluefin tuna schools. Our approach relies on ecological knowledge of bluefin tuna to extrapolate survey observations across areas not sampled by correcting survey abundance estimates based on range of movement search pattern and depth preference. We demonstrate how separate findings obtained through the analysis of data collected across different spatial and temporal scales can be integrated to correct and calibrate estimates of population abundance. We obtain fitted estimates of seasonal abundance of bluefin tuna in the GOM during 1994–1996 in the range of 45,000–51,000 individuals. If tuna behaviour is not accounted for, we estimate that the base or residual survey precision would be 4–7% determined from analysis of recent spotter survey data in the study region. We estimate the precision in estimating seasonal abundance accounting for tuna behaviour to lie within a range of 1,301–3,302%. Under hypothetical future improvements in survey design that achieve a precision of 20% in transect length and placement, we calculate net-precision to lie within a range of 82–93%. This calculation assumes reducible uncertainty in school size estimation and irreducible uncertainty in movement and school-aggregation behaviour. We infer that survey precision could be further reduced by 43–32% to attain 10–50% in which a 3–8 years adaptive survey design may reliably detect a seasonal abundance trend.     

Contributions of stable-isotope data to elucidating food webs of Mediterranean rocky littoral fishes

The food webs of rocky infra-littoral ecosystems in the Mediterranean have been little studied. In this investigation stable isotopes and dietary data were compared in an attempt to describe features of the food webs concerned. δ¹³C and δ¹⁵N were determined for plants, invertebrates and fishes from the Bay of Calvi, Corsica. Dietary data were derived from the literature. δ¹³C of plants ranged from –8.59‰ to –33.74‰, of benthic invertebrates from –17.0‰ to –20.52‰, of planktonic invertebrates from –20.08‰ to –22.34‰ and of fishes from –16.27‰ to –19.59‰. δ¹⁵N was generally greater at higher trophic levels. δ¹⁵N of plants was 0.95–2.92‰, of benthic invertebrates 1.69–6.54‰, of planktonic invertebrates 3.51–6.82‰ and of fishes 4.63–9.77‰. ¹³C enrichment tended to be associated with benthic food chains and ¹³C depletion with planktonic chains. Stable-isotope data suggested more varied diets for many species than implied by gut-contents data. Omnivory and trophic plasticity were widespread, and many consumers fed lower down the food chain than previous studies had suggested. Both stable-isotope and gut-contents analysis resolved differences between fishes feeding on planktonic and benthic prey and indicated that the herbivorous fish Sarpa salpa fed on a diet substantially different from that of other fishes. Zooplankton were important in the diets of several consumers (both primary and secondary), as was plankton derived detritus. One species of fish previously identified as planktivorous was shown to feed largely on benthic organisms, whilst several species of benthic invertebrates may feed on plankton-derived detritus. Although herbivores seemed to obtain most of their C from macroalgae, δ¹⁵N data suggested that many of these animals supplemented their intake of N, although gut-contents analysis did not provide evidence for such uptake. The isotopic data have elucidated several features of the food web which we would not otherwise have detected. Received: 26 April 1999 / Accepted: 24 September 1999     

Determinants of zinc intake in low-Income black and white pregnant women

A prospective study was conducted to evaluate and compare the determinants of dietary zinc intake in black and white low-income pregnant women. The study population consisted of 1298 low-income women (70% Black, 30% White) who received prenatal care at University Hospital at the University of Alabama in Birmingham from 1985 to 1989. Various maternal characteristics were evaluated at the first prenatal visit. Two 24 h recalls were obtained at 18 and 30 wk of gestation to calculate the intakes of dietary zinc and other nutrients. Student’st test, ξ², Pearson correlation coefficients, and multiple regression analyses were used to compare and evaluate the determinants of zinc and other nutrient intakes in Black and White subjects. The mean prepregnancy body mass index and the mean intake of zinc, energy, and all the other nutrients except calcium were significantly higher in Black than in White subjects. There was a significant correlation between zinc and energy intake (r- 0.69,p = 0.001). Age, marital status, parity, socioeconomic status, smoking, and alcohol intake were not significant predictors of zinc or other nutrient intakes. After adjusting for energy intake, race was the only significant predictor of dietary zinc intake. Race and energy intake explained 24% of the variation in zinc intake. Results of this study indicate that after adjusting for other covariates, race and energy intakes are the only predictors of zinc intake in low-income pregnant women.     

Nutritional quality of gorilla diets: consequences of age,sex, and season

We tested the effects of age, sex, and season on the nutritional strategies of a group of mountain gorillas (Gorilla beringei) in the Bwindi Impenetrable National Park, Uganda. Through observations of food intake of individual gorillas and nutritional analyses of dietary components over different seasons and environments, we estimated nutrient intake and evaluated diet adequacy. Our results suggest that the nutritional costs of reproduction and growth affect nutrient intake; growing juveniles and adult females ate more food and more protein per kilogram of metabolic body mass than did silverbacks. The diets of silverback males, adult females, and juveniles contained similar concentrations of protein, fiber, and sugar, indicating that adult females and juveniles did not select higher protein foods than silverbacks but rather consumed more dry matter to ingest more protein. Juveniles consumed more minerals (Ca, P, Mg, K, Fe, Zn, Mn, Mo) per kilogram of body mass than adult females and silverback males, and juveniles consumed diets with higher concentrations of phosphorous, iron, and zinc, indicating that the foods they ate contained higher concentrations of these minerals. Seasonally, the amount of food consumed on a dry weight basis did not vary, but with increased frugivory, dietary concentrations of protein and fiber decreased and those of water-soluble carbohydrates increased. Energy intake did not change over the year. With the exception of sodium, gorillas ate diets that exceeded human nutrient requirements. A better understanding of the relative importance of food quantity and quality for different age–sex classes provides insights into the ways in which gorillas may be limited by food resources when faced with environmental heterogeneity.     

Linear measurement error models with restricted sampling

The relationship between nutrient consumption and chronic disease risk is the focus of a large number of epidemiological studies where food frequency questionnaires (FFQ) and food records are commonly used to assess dietary intake. However, these self-assessment tools are known to involve substantial random error for most nutrients, and probably important systematic error as well. Study subject selection in dietary intervention studies is sometimes conducted in two stages. At the first stage, FFQ-measured dietary intakes are observed and at the second stage another instrument, such as a 4-day food record, is administered only to participants who have fulfilled a prespecified criterion that is based on the baseline FFQ-measured dietary intake (e.g., only those reporting percent energy intake from fat above a prespecified quantity). Performing analysis without adjusting for this truncated sample design and for the measurement error in the nutrient consumption assessments will usually provide biased estimates for the population parameters. In this work we provide a general statistical analysis technique for such data with the classical additive measurement error that corrects for the two sources of bias. The proposed technique is based on multiple imputation for longitudinal data. Results of a simulation study along with a sensitivity analysis are presented, showing the performance of the proposed method under a simple linear regression model.     

Age,growth and reproductive biology of the silky shark,Carcharhinus falciformis,and the scalloped hammerhead,Sphyrna lewini,from the northwestern Gulf of Mexico

Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent >80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at >225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L_∞ = 291 cm TL, K = 0.153, t₀ = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L_∞ = 329 cm TL, K = 0.073, t_o = −2.2 yr.     

Nutritional requirements for maintenance of body weight and fat deposition in the long-distance migratory garden warbler, Sylvia borin (Boddaert)

Intake of food, protein, fat and carbohydrates and their fecal output and the birds' weights were recorded during different feeding trials with specific nutrient reduced diets in the old-world long-distance migratory garden warbler. The birds' body weights were affected by low dietary protein as well as low dietary fat levels. Low dietary protein and fat levels were associated with significant changes in daily gross and net food intake and in the efficiency of food and nutrient utilization. Birds fed on diets with low nutrient levels for an extended length of time recovered in weight after an initial weight loss. They obviously compensated the restricted nutrient levels primarily by increasing the daily food intake and by changing the efficiency of food and nutrient utilization. Effects of restricted dietary nutrient levels on body weight and adaptation depended on the previous composition of the food. The average daily net fat intake was much higher than the average daily net protein intake, both for maintenance of a constant body weight and for successful regain of weight. The data were further discussed with respect to the role of a fruit diet in omnivorous passerine birds.