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This review is intended to provide an overview of endoscopic techniques for tympanic membrane closure procedures with focus on prospective randomized studies and latest surgical trends in endoscopic tympanic membrane closure. Minimally invasive endoscopic procedures for tympanic membrane closure are safe and suitable techniques. Endoscopic techniques offer similar postoperative outcomes in terms of graft intake rate and air bone gap closure compared to microscopic approaches. The endoscopic approach provides favorable cosmetic outcomes, less postoperative pain and shorter surgical time. Therefore, endoscopic ear surgery has evolved into a promising, minimally invasive alternative to the microscopic technique for closing tympanic membrane perforations evidenced by an increasing number of scientific publications with comparable, if not superior outcomes for the endoscopic technique.

International audience; In ruminants, feeding behaviour variables are parameters involved in feed efficiency that show variation among individuals. This study aimed to evaluate during the first two production cycles in ruminants the repeatability of feed intake pattern, which is an important aspect of feeding behaviour. Thirty-five dairy goats from Alpine or Saanen breeds were housed in individual pens at four periods (end of first gestation, middle of first and second lactations and middle of second gestation which is also the end of first lactation) and fed a total mixed ration (TMR) ad libitum. Individual cumulative dry matter intake (DMI) was automatically measured every 2 min during the last 4 days of each period. Feed intake pattern was characterized by several measures related to the quantity of feed eaten or to the rate of intake during the 15 h following the afternoon feed delivery. Two main methods were used: modelling cumulative DMI evolution by an exponential model or by a segmentation-clustering method. The goat ability to sort against dietary fibre was also evaluated. There was a very good repeatability of the aggregate measures between days within a period for a given goat estimated by the day effect within breed and goat, tested on the residual variance (P > 0.95). The correlations between periods were the highest between the second and either the third or fourth periods. With increasing age, goats sorted more against the fibrous part of the TMR and increased their initial rate of intake. Alpine goats ate more slowly than Saanen goats but ate during a longer duration. Principal component analysis (PCA) was performed on all the aggregate measures of feed intake patterns. The factor score plots generated by the PCA highlighted the opposition between the different measures of feed intake patterns and the sorting behaviour. The projection of the animals on the scoring plots showed a breed effect and that there was a continuum for the feed intake pattern of goats. In conclusion, this study showed that the feed intake pattern was highly repeatable for an animal in a given period and between periods. This means that phenotyping goats in a younger age might be of interest, either to select them on feeding behaviour and choose preferentially the slow eaters or to adapt the quantity offered and restrict feed delivery to the fast eaters in order to increase feed efficiency and welfare by limiting the occurrence of acidosis, for example.

Heavy metal pollution is an issue of wide concern owing to the toxic and bioaccumulative properties of many heavy metals and their tendencies to persist in the environment. The Haihe River is an important river in the Beijing–Tianjin–Hebei region, and heavy metal pollution of the basin has attracted considerable attention. This study determined the concentrations of 14 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, and Zn) in water, sediments, and fish samples from the Haihe River basin. The results showed that the concentrations ranged from 0.08 μg L−1 to 60.49 μg L−1 in water, 0.11 mg kg−1 to 229.20 mg kg−1 in sediments, and 0.01 mg kg−1 to 11.72 mg kg−1 in fish. We derived the ambient water quality criteria (AWQC) value of each heavy metal with respect to human health, and then performed a comprehensive risk assessment according to the native parameters. The human health AWQC values for the assessed 14 heavy metals ranged from 0.16 μg L−1 to 726.53 μg L−1. The health risks posed by As, Cr, Hg, and Sb and the ecological risks associated with Ni, Cu, Cr, Zn, Cd, Co, Hg, and Sn were found to be issues of concern. The results of a sensitivity analysis revealed that the highest contributing parameter was i) the concentration in water (Cw) for Cd, Co, Mn, Sb, and Sn; ii) the intake rate of water (IRw) for As, Ba, Cr, Hg, Ni, Pb, and Se; and iii) the concentration in fish (Cf) for Cu and Zn. The results of this research could contribute to the information required for water quality assessments and the development of water quality standards.

The goal of the study was to characterize risk pertaining to seafood consumption patterns following the Deepwater Horizon oil spill, among school children (K to 4th grade) residing in close proximity to the Gulf of Mexico in Mobile County, Alabama.Responses on seafood consumption pattern including the type of seafood and intake rate during the pre and post oil spill periods, from parents of 55 school children from three schools located20mile radius from the Gulf of Mexico shoreline (coastal group) were compared with those from parents of 55 children from three schools located ≥20miles away from the shoreline (inland group). We also estimated levels of concern (LOCs) in seafood for selected chemicals found in crude oil including heavy metals, and polycyclic aromatic hydrocarbons (PAH), and dioctyl sodium sulfosuccinate (DOSS), the primary compound in dispersants.The coastal group ate more seafood consisting primarily of crustaceans (62% vs. 42%, p=0.04) and fin fish (78% vs. 58%, p=0.02) from the Gulf of Mexico compared to the inland group, while the inland group ate more fin fish not found in the Gulf of Mexico (62% vs. 33%, p0.01). In the post-oil spill time period, both groups substantially reduced their consumption of sea food. On average, the coastal group ate ≥2 seafood meals per week, while the inland group ate ≤1 meal per week; these frequency patterns persisted in the post oil-spill period. Comparison of the estimated LOCs with contaminant levels detected in the seafood tested by the Food and Drug Administration and National Oceanic and Atmospheric Administration, post-oil spill, found that the levels of PAHs, arsenic, and DOSS in seafood were 1-2 orders of magnitude below the LOCs calculated in our study. Levels of methyl mercury (MeHg) in the seafood tested pre- and post- oil spill were higher than the estimated LOCs suggesting presence of higher levels of MeHg in seafood independent of the oil spill.In sum, the study found higher than average seafood consumption among children along the Mobile coastal area when compared to the inland children and the National Health and Nutrition Examination Survey (NHANES) estimates. Risk characterization based on the LOCs indicated no increase in risk of exposure despite higher seafood consumption rates among the study population compared to the general population.

Pigs are housed in groups during the test period. Social effects between penmates may affect average daily gain (ADG), backfat thickness (BF), feed conversion rate (FCR), and the feeding behaviour traits of pigs sharing the same pen. The aim of our study was to estimate the genetic parameters of feeding behaviour and production traits with statisticalmodels that include social genetic effects (SGEs). The data contained 3075 Finnish Yorkshire, 3351 Finnish Landrace, and 968 F1-crossbred pigs. Feeding behaviour traits were measured as the number of visits per day (NVD), time spent in feeding per day (TPD), daily feed intake (DFI), time spent in feeding per visit (TPV), feed intake per visit (FPV), and feed intake rate (FR). The test period was divided into five periods of 20 days. The number of pigs per pen varied from 8 to 12. Two model approaches were tested, i.e. a fixed group size model and a variable group size model. For the fixed group size model, eight random pigs per pen were included in the analysis, while all pigs in a pen were included for the variable group size model. The linear mixed-effectsmodel included sex, breed, and herd*year*season as fixed effects and group (batch*pen), litter, the animal itself (direct genetic effect (DGE)), and penmates (SGEs) as random effects. For feeding behaviour traits, estimates of the total heritable variation (T-2 +/- SE) and classical heritability (h(2) +/- SE, values given in brackets) from the variable group size model (e.g. period 1) were 0.34 +/- 0.13 (0.30 +/- 0.04) for NVD, 0.41 +/- 0.10 (0.37 +/- 0.04) for TPD, 0.40 +/- 0.15 (0.14 +/- 0.03) for DFI, 0.53 +/- 0.15 (0.28 +/- 0.04) for TPV, 0.66 +/- 0.17 (0.28 +/- 0.04) for FPV, and 0.29 +/- 0.13 (0.22 +/- 0.03) for FR. The effect of social interaction was minimal for ADG (T-2 = 0.29 +/- 0.11 and h(2) = 0.29 +/- 0.04), BF (T-2 = 0.48 +/- 0.12 and h(2) = 0.38 +/- 0.07), and FCR (T-2 = 0.37 +/- 0.12 and h(2) = 0.29 +/- 0.04) using the variable group size model. In conclusion, the results indicate that social interactions have a considerable indirect genetic effect on the feeding behaviour and FCR of pigs but not on ADG and BF. (C) 2020 The Authors. Published by Elsevier Inc. on behalf of The Animal Consortium.

Intake rates by large herbivores are governed by among other things plant traits. We used Masai giraffe (Giraffa camelopardalis tippelskirchi Matschie) as study animals, testing whether they as very large browsers would follow the Jarman–Bell principle and maximize intake rate while tolerating low forage quality. We worked in Arusha National Park, Tanzania. We investigated how intake rate was determined by bite mass and bite rate, and show that bite mass and bite rate were determined by plant characteristics, governed by inherent plant traits, plant traits acquired from previous years’ browsing, and season. We predicted that; (1) bite mass would be larger in trees without spines than with (2) bite mass would be larger in the wet season than in the dry, (3) bite rate would be higher in spinescent trees than in non-spinescent, (4) bite rate and/or bite mass would increase with previous years’ browsing, (5) bite mass, bite rate or browsing time per tree would be highest for high trees with large, although still available canopies. Visual observations were used to collect data on tree attributes, number of bites taken and time of browsing. Sample size was 132 observed giraffe. We found that bite mass was larger in spineless than in spinescent trees and was larger in the wet season than in the dry. Bite rate, but not bite mass, increased with increasing browsing in previous years and was highest on two to three meter high trees and in spinescent trees. Intake rate followed bite mass more than bite rate and was higher in spineless than in spinescent trees, higher in the wet season than in the dry, and tended to increase with tree height. Giraffe did not prioritize the highest intake rate, but browsed much on Acacias giving a high quality diet but a low intake rate.

We investigated the hypothesis that not only forage allowance but also sward structure affects daily forage intake by beef heifers on natural grasslands of the Pampa Biome (southern Brazil). We used data from a long-term experiment, which has been managed by forage allowance levels since 1986. The objective was to investigate sward management targets that maximize daily forage intake. During January and December 2009, we evaluated the effect of forage allowance on forage mass, sward height and tussock frequency, and its consequences on dry matter intake (DMI). The experiment was arranged in a randomized complete block design with two replicates. Treatment was level of daily forage allowance (4, 8, 12, and 16 kg dry matter [DM] per 100 kg of animal body weight [BW]). Data were analyzed using regression, principal component analysis, and descriptive analyses from three-dimensional contour graphs with the data of sward structure, DMI, and DMI rate. Results demonstrated that DMI was positively correl...

Tall grasses (>1 m tall) are an important forage resource for grazing ruminants. Understanding the ingestive behavior and short-term intake rate of cattle grazing on tall grasses will help facilitate grazing management of tall grass pastures. The aim of this study was to determine the allocation of jaw movements in grazing cattle in relation to tall grasses and to assess whether such allocations of jaw movements are effective for maintaining a short-term intake rate. Four plants were used as test plants: bahiagrass ( Paspalum notatum Flugge; a short grass), Sudangrass ( Sorghum × drummondii ; a typical tall grass) and two growth forms of a dwarf bamboo ( Sasa senanensis ; a semi-woody form of tall grass): a naturally growing form (NGDB, approximately 2 m tall) and a form that is under grazing (DBUG, P P P >0.05), except for Sudangrass. Cows ingested Sudangrass at a lower intake rate than observed for the other plants ( P

Spices are an essential part of our food preparations and are considered a potential source of health-protective components. However, spices may also contain some toxic substances primarily aflatoxins and heavy metals. This study aimed to quantify the level of total aflatoxins and three most toxic heavy metals i.e. lead (Pb), arsenic (As) and cadmium (Cd) in commercially available non-branded and branded spices. Furthermore, risk assessment through aflatoxins and heavy metals was performed by computing the values of Margin of Exposure (MOE) and Total Hazard Quotient (THQ), respectively. The concentration of aflatoxins was recorded higher in non-branded spices while heavy metals especially Pb was recorded higher in branded spices. MOE values for aflatoxins through spices consumption indicated that all age group of people were consuming aflatoxins above the threshold level. The THQ values for heavy metals toxicity assessment were found within the acceptable ranges. Females, especially above 24 years of age, were found at more risk as compared to male, due to their higher intake rate of spices.

This study proposes an environmental- and health-risk-induced remediation design approach for benzene-contaminated groundwater. It involves exposure frequency and intake rates that are important but difficult to be exactly quantified as breakthrough point. Flexible health-risk control is considered in the simulation and optimization work. The proposed approach is then applied to a petroleum-contaminated site in western Canada. Different situations about remediation durations, public concerns, and satisfactory degrees are addressed by the approach. The relationship between environmental standards and health-risk limits is analyzed, in association with their effect on remediation costs. Insights of three uncertain factors (i.e. exposure frequency, intake rate and health-risk threshold) for the remediation system are also explored, on a basis of understanding their impacts on health risk as well as their importance order. The case study results show that (1) nature attenuation plays a more important role in long-term remediation scheme than the pump-and-treat system; (2) carcinogenic risks have greater impact on total pumping rates than environmental standards for long-term remediation; (3) intake rates are the second important factor affecting the remediation system's performance, followed by exposure frequency; (4) the 10-year remediation scheme is the most robust choice when environmental and health-risk concerns are not well quantified.

Eight mature horses were used in a 4 × 4 Latin square design to determine the effect of restricted pasture access on dry matter intake rate (DMIR), energy intake, and fecal pH. Horses were randomly assigned to one of four groups (HGRPs), each containing two horses. HGRPs were randomly assigned to one of four treatments consisting of 3, 6, 9, or 24 hours of pasture access, for a period of 7 days. Treatments were switched every 7 days. The 3- and 6-hour groups were fed free choice mature grass hay while not grazing. Daily pasture dry matter intake (DMI) for each HGRP was estimated by calculating the difference between initial herbage mass of the grazing cell before grazing and residual herbage mass after 7 days of grazing. Total dry matter intake was the sum of pasture and hay DMI for the 3- and 6-hour treatments. Fecal pH was measured on day 7 of each period. Response variables were analyzed using analysis of variance for Latin square design. Restricting pasture access decreased mean pasture DMI (P = .02), pasture dietary energy (DE) (P = .02), and fecal pH (P

Digestive capabilities of nectar-feeding vertebrates to assimilate sugars affect their ability to acquire and store energy and could determine the minimal temperatures at which these animals can survive. Here, we described the sugar digestive capability of Leptonycteris nivalis and related it with its capacity to live in cold environments. We measured the enzymatic activity, food intake rate and changes in body mass of bats feeding at four different sucrose concentrations (from 5 to 35% wt./vol.). Additionally, we used a mathematical model to predict food intake and compared it with the food intake of bats. L. nivalis was able to obtain ~ 111.3 kJ of energy regardless of the sugar concentration of their food. Also, bats gained ~ 2.57 g of mass during the experimental trials and this gain was independent of sugar concentration. The affinity (1 / K m ) of sucrase (EC 3.2.1.48) was one order of magnitude higher relative to that reported for its sister species Leptonycteris yerbabuenae (0.250 and 0.0189 mmol − 1 L, respectively), allowing this species to have a higher energy intake rate. We propose that the high ability to acquire energy conferred L. nivalis the faculty to invade cold environments, avoiding in this way the ecological competition with its sympatric species L. yerbabuenae .

Feed intake behavior was studied between 9 weeks of age and slaughter in a total of 36 gilts, 32 immunocastrates, 33 surgically castrated barrows and 33 boars from 36 litters. Consequences for the concentration of substances contributing to off odor of pork (skatole, indole) were evaluated. Animals were kept in groups of 12 pigs of the same sex and treatment and fed ad libitum (13.4 MJ ME, 17% CP, 1.1% lysine). Individual feed intake behavior was recorded continuously by an electronic feeder. Immunocastration was carried out with two injections of Improvac with at least 4 weeks between both injections (1st: 12 to 17 weeks of age, 2nd: 19 to 21 weeks of age). Feed intake/day increased from an average of 0.91 ± 0.02 kg/day up to 3.15 ± 0.04 kg/day before slaughter. This increase was associated with a 50% reduction in the number of meals/day (from 15.8 ± 0.44 to 7.2 ± 0.29 meals/day). The larger meal sizes resulted from an increase in both, the duration of feed intake/meal and the feed intake rate (g/min). In addition, sex and treatment differences were observed: Feed intake in boars was lower than in all other groups due to a reduction in the number of meals/day and in the time spent feeding/day. In females, time spent feeding/day was quite similar to boars, but resulted from a higher number of meals of shorter duration. Barrows had a significantly higher feed intake because of a higher number of meals/day resulting in more time spent feeding/day. The feed intake rate was similar in boars, gilts and barrows and showed an increasing trend during the study, starting from about 15 g/min up to four times the amount. Immunocastration affected feed intake behavior severely, especially the meal size increased dramatically because of higher feed intake rate, which exceeded that of all other groups by 25% at the end of the study. The number of meals/day was not influenced by immunocastration and was almost identical to that of boars. Highest skatole concentrations were measured in fat of boars, whereas indole concentrations were higher in immunocastrates than in all other groups. In gilts and barrows, skatole concentrations were related to growth rate. Additionally, the feeding rate was an important factor explaining the variability in skatole/indole concentrations in adipose tissue. The physiological mechanisms however need further clarification.

One of the variables in the structure of the sward with the most influence on the short-term herbage intake rate by grazing ruminants is the canopy height. The objective of this study was therefore to characterise the effect of the canopy height on short-term herbage intake rate using Sorghum bicolor cv BR 501. as a reference. Two experiments were conducted at Research Station of the Federal University of Rio Grande do Sul, Brazil, between December 2009 and April 2010. The treatments in experiment 1 were used to determine the influence of the pre-grazing canopy height on the short-term herbage intake and consisted of six canopy heights (30, 40, 50, 60, 70 and 80 cm). The treatments in experiment 2 used the pre-grazing canopy height from experiment 1 that maximised the short-term herbage intake rate to evaluate the influence of the severity of grazing down (16, 33, 50, 67 and 84%) on the herbage intake. Both experiments used a completely randomised block design, with two replicates in experiment 1 and three replicates in experiment 2. Four heifers (24 ± 2 months and 306 ± 56.7 kg) were used in experiment 1. Three of these animals were used in experiment 2, which were then 26 ± 2 months and 339 ± 45.5 kg. The short-term herbage intake rate was measured by weighing the heifers pre- and post-grazing, corrected for insensible weight losses. The number of grazing jaw movements (biting and non-biting) was counted automatically using an IGER Behaviour Recorder. In both experiments, the sward measurements included the pre- and post-grazing canopy height, the pre-grazing herbage mass and the vertical distribution of morphological components. In experiment 2, the post-grazing herbage mass was also measured. The results showed that the grazing canopy height that maximised the short-term herbage intake rate was approximately 50 cm. The grazing down protocol showed that the short-term herbage intake rate was constant until the depletion of 40% of the optimal pre-grazing canopy height. After this level of depletion, there was a marked reduction in the short-term herbage intake rate. The results show that the best target management height in a Sorghum cv. BR 501 pasture, allowing for high levels of the short-term herbage intake rate, is 50 cm. With intermittent stocking, this level should be considered as the pre-grazing canopy height, and the level of herbage depletion should not exceed 40%.

Eight mature horses weighing 576 ± 32 kg (mean ± SD) were used to compare differences in pasture dry matter (DM) intake rate in October (period 1), February (period 2), and May (period 3). Horses were randomly assigned to a pair of adjacent 5 m × 5 m grazing cells containing nontoxic, endophyte-infected tall fescue. Horses had access to each cell for 4 hours. Pasture DM intake rate was estimated over the entire 8-hour period by measuring the pre- and postgrazing herbage mass within each cell and was expressed as kg DM/100 kg body weight (BW)/hr. Mean 8-hour DM intake rate in period 1 (0.17 ± 0.01 kg DM/100 kg BW/hr) was greater (P

A study was undertaken to develop a model for the prediction of dry matter intake by lactating Holstein Friesian dairy cows. To estimate the model parameters, a calibration dataset was compiled with the data from 32 feeding experiments conducted at 9 different sites. The database contained weekly information on 1507 lactating Holstein Friesian dairy cows regarding their diet composition and feed analysis, together with their individual voluntary feed intake, milk yield (MY), milk composition, parity, days in lactation and days pregnant. Dry matter intake was predicted from feed and animal characteristics. The feed chemical composition and digestibility can be related to feed degradation, bulk volume, intake rate, palatability and other factors influencing feed intake. Therefore, the data of standard feed analysis were used to estimate the satiety value of numerous commonly used feeds and forages. The satiety value is the measure of the extent to which a feed limits intake. The cows' ability to process the intake-limiting satiety value-units is expressed as the feed intake capacity, which is predicted from parity, days in milk and days of pregnancy which are indicators of the size and physiological state of the cow. This study shows that feed intake can be predicted using a limited number of easy-to-measure inputs that are available on commercial farms, yet reasonably biologically sound. Because the model inputs are not related to animal output (milk yield or body weight), future extension of the intake model with models for the prediction of animal performance is possible.

Consistent individual differences in behaviour have now been documented in a broad range of organisms over a variety of contexts. However, individual differences in social contexts have received less attention. We explored the consistency and temporal persistence of individual differences in tactic use in a producer–scrounger foraging game using two sets of flocks of wild-caught nutmeg mannikins, Lonchura punctulata. With both sets of birds, we observed significant individual differences in tactic use that persisted under different food distributions and when flock members were reunited at a 6-month interval with the same flockmates but not when flock members were different. In another experiment, in which birds with high-scrounging profiles were made to forage in the same flock, the corporate frequency of scrounging was no higher, and the intake rate no lower than in flocks made up of intermediate- or low-frequency scroungers. Taken together our experiments suggest that persistent individual differences can arise from dynamics that are peculiar to the group in which they occur, underlining the importance of companions’ identity in determining tactic use in this game. Behavioural plasticity can erase idiosyncratic individual differences in games with frequency-dependent payoffs when group composition changes.

Relatively little information is available on foraging behavior of animals grazing tall grasses (> 1 m tall) despite extensive works on grasses as a sward ( Zea mays L.) plants to quantify how animals exploit a tall grass in terms of jaw movement and dry matter (DM) intake. In the feeding tests, Japanese Black cows (1 animal in each test) were allowed to graze a maize plant erected at the center of an arena (6 m × 6 m). Each plant was prepared to have 8 leaves of full- or half-size (trimmed to the half-length). The mass of leaves removed by the animals was estimated based on the size (length × width)–weight and defoliation length–weight relationships in individual leaves on the stem. The cows foraged the maize plants at similar rates of jaw movement for the full- and half-size leaves (60.6 vs. 63.2 cycles min − 1 , respectively). The number of jaw movements allotted per leaf was significantly greater for the full-size leaves than for the half-size leaves (9.3 vs. 6.9 cycles leaf − 1 ), reflecting the difference in leaf mass (4.20 vs. 2.76 g DM leaf − 1 ). The cows grazed mainly lower leaves at the initial stage of feeding and progressively shifted to upper leaves. They seized a full-size leaf by the proximal or mid part for ease of prehension, and seized a half-size leaf by the mid or distal part because of higher accessibility. Furthermore, the cows were able to process more than 1 leaf by a single jaw movement. Both intake per jaw movement (0.43 vs. 0.35 g DM cycle − 1 ) and intake rate (26.0 vs. 22.3 g DM min − 1 ) were similar for the full- and half-size leaves, which was attributed to the fact that the half-size leaves were still long (45.9 ± 1.0 cm) and broad (10.2 ± 0.1 cm as the maximal width) enough to ensure bite mass comparable to that from the full-size leaves. The results show that cattle have the ability to forage a tall grass efficiently by controlling the allotment of jaw movements among the leaves on the stem and among the positions within the individual leaves. At the same time, the results suggest that harvesting by cattle of a tall grass is potentially less efficient than that of a tall, dense grass sward.

International audience; Grazing low-mass pastures is almost inevitable when extending the grazing season into late winter to reduce feed costs, cows' performance being potentially affected. An experiment was carried out to estimate the performance, pasture intake (PI) and behavioural adaptation of dairy cows when grazing low-mass pastures at LOW. MEDIUM and HIGH pasture allowances (PA), corresponding to 19,32 and 46 kg OM/cow per day above ground level, respectively. The study took place in the late winter of 2008 on good quality perennial ryegrass/white clover pastures with a mean pasture mass and a pre-grazing platemeter height of 2.3 t OM/ha above ground level and 5.8 cm, respectively. Each cow was supplemented with 4.4 kg OM of maize silage and 2.0 kg OM of cereal concentrate. Daily time at pasture was restricted to 9 h between the am and pm milkings. Eighteen midlactation Holstein cows (twelve multiparous and six primiparous) were used in a 3 x 3 orthogonal Latin square design with three consecutive periods of 13 days. On average, the cows produced 25.3 kg of milk and total OM intake was 14.4 kg/d. Pasture OM intake averaged 7.9 kg/d and linearly increased from LOW to HIGH (+ 0.04 kg/kg PA). Similarly, milk production per cow ( + 0.09 kg/kg PA) and milk protein concentration (+ 0.04 g/kg per kg increase in PA) linearly increased with increasing PA. Milk fat concentration, on the other hand, decreased by 0.10 g/kg per kg increase in PA. The daily grazing time (430 min) and the proportion of time spent grazing (79%) were not affected by PA. On average, pasture intake rate was low (19 g OM/min) and linearly increased from 16.9 g OM/min in LOW to 20.7 g OM/min in HIGH. In the present study, the PI was limited even at high PA because of the cumulative effect of the low-mass pasture (low intake rate) and the restricted access time (short grazing time). Consequently, the effect of PA on PI was low. However, the milk production response to variations in PI was high because of the low energy balance recorded in all treatments. (C) 2010 Elsevier B.V. All rights reserved.

It is often necessary to estimate the weight that an individual may be capable of gaining depending on its degree of activity. A simple individual-based model was developed for studying the dynamics of weight in terms of daily behavior and ingestion rate. It was based on the balance between the individual's energy intake and the cost of its daily activities. Costs depend on the weight of the individual and the photoperiod, as well as on the time spent on each activity. Different combinations of ingestion rate, individual's weight, photoperiod length, and time assigned to different activities were used for simulating the weight dynamics, taking the species Rhea americana as a study case. Estimations of energetic costs of the activities were obtained from specialized literature. Using different photoperiods and individual behaviors, the model yields field metabolic rate (FMR) values in agreement with those obtained from direct measurements for other omnivorous bird species.

This study compares two procedures for the study of choices that differ in time and amount, namely the self-control and patch procedures. The self-control procedure offers animals a binary mutually exclusive choice between a smaller-sooner and larger-later option. This procedure dominates the choice literature. It seems to address the idea of choice in a general, but relatively abstract way. Animals in the self-control situation frequently prefer the smaller-sooner option even when the larger-later option yields a higher long-term intake rate. In contrast, the patch procedure poses an economically similar question, but simulates the naturally occurring problem of patch exploitation. In the patch procedure, animals choose between leaving and staying. Emerging evidence suggests that animals perform better and achieve higher long-term intake rates in the patch situation. This observation raises the question of how a single set of choice mechanisms could produce these different outcomes. The experiment presented here tests two hypotheses about the relationship between the patch and self-control situations. First, it asks whether the short-term rate rule can predict choice behavior in both situations. Second, it tests the second-delivery hypothesis which holds that the patch situation favors choosing the larger more delayed option (staying) because this option ultimately leads to two food deliveries. The results of this experiment convincingly reject both of these hypotheses. Indeed, our results suggest that none of the simple rules based on time and amount can explain the observed differences between the patch and self-control situations. This result challenges the generality of existing models of choice.

The most important problem in boric acid production from colemanite ores with H2SO4 is the formation of MgSO4 impurity due to the partial decomposition of clay minerals in the reaction media. Increase of MgSO4 concentration in solution may be balanced by the discharge of mother liquor which leads to decrease the efficiency of the process. Therefore, the intake rate of MgSO4 should be lowered for obtaining high purity product in a high yield process. In order to control the intake rate of MgSO4 impurity, propionic acid, which does not decompose the clay minerals, is used in an acid mixture with H2SO4. Batch wise laboratory experiments showed that the higher the propionic acid in reacting acid mixture, the lower the magnesium intake rate. When 10% of required H2SO4 replaced by propionic acid, magnesium intake concentration decreased to approximately half of the value obtained in the reaction with H2SO4.

Feed palatability and in vivo apparent digestibility of nutrients were compared in horses fed concentrates in which barley was, or not, partially substituted by 8% linseed oil. According to a cross-over design, three geldings and one stallion were fed at near maintenance level hay plus low or high fat diet (50/50). The last days of each 3-months sub-periods, partial faeces collections were performed and concentrate intake rate was measured to estimate the digestibility and the palatability of the diet. The inclusion of linseed oil did not affect the palatability of the diet and increased significantly (P

This study, conducted in the southwestern Argan forest of Morocco, aimed to assess goat feeding behaviour and goat diet composition. Overall grazing time averaged 387 min/day and represented on average 70% of total time when the goats were released on pasture. Grazing time was higher during winter months. Bipedal grazing was low and never exceeded 10%. Soil grazing varied according to the period of the year. Aerial grazing increased when herbaceous layer was depleted. Walking activity that accounted for 24% of the presence of goats on pasture, varied with the period of the year. Resting time accounted for less than 39 min contributing less than 6% of the temporal behavior budget. The contribution of all argan to the goat's diet ranged from a minimum of 47% in June to a maximum of 84% in December. Aerial argan leaves contributed continuously to goat diets a proportion from 35% to 68%. Under-tree grazing accounted for 50% during June when herbaceous plants and stubble were available, but less than 15% when they were depleted. Total intake changed with advance in season. Total goat intake reached its lowest level when animals spent large amounts of their time grazing argan trees in response to shortage of feed on the ground. Variation of the intake rate was mainly due to bite size, since rate of biting varied little among months. Goats ingested larger bite size from March through June when argan fruits were available and when diversity of availability was the highest. The goats adaptation capacity in argan forest allows a kid meat production when other ruminants such as sheep probably would not be able to do.

Ants of the same size can vary their intake rate of a given sucrose solution depending on the colony's needs for carbohydrates. As this capacity has not yet been described for another insect, the question of how they can do that was the focus of our work. When viscosity and ant-morphometry remain constant, changes in intake rate can only be attributed to the sucking forces. The aim of this study was to analyze the nectar sucking activity in the ant Camponotus mus. Feeding behavior seems to be under motivational control; therefore, we developed a non-invasive experimental device. We recorded the electrical signal generated during nectar feeding by offering ants sucrose solutions of different concentrations (from 10%w/w to 70%w/w). The signal frequency was between 2 and 12 peaks/s. We could distinguish two different patterns of electrical signal during feeding depending on the solution concentration. Only the more concentrated solutions reached frequencies higher than 7 peaks/s and the signal performance was quite irregular. For the other concentrations (10%, 30% and 50%), signal frequencies were lower than 6 peaks/s and the signal pattern was sinusoidal, regular and decreased with intake in all cases. We discuss the possible implications of these two signal patterns.

Many aspects of the management of grazing systems are directly or indirectly related to the rate of herbage intake achieved by the animal. Intake rate depends, in part, on the time budget of the process, which derives from the basic behavioural component—the jaw movement. Chewing and biting jaw movements have generally been considered mutually exclusive, but acoustic monitoring has demonstrated the existence of the compound chew–bite jaw movement. We used a simple model to examine the implications of chew–bites for the forage-intake time budget, and tested it empirically. The model defines the total number of jaw movements per bite ( α ) and the number of chew actions per bite ( β ) in relation to the allocation of jaw movements between chews, bites and chew–bites. We examined empirically the variation among animals in the allocation of jaw movements for cattle ( Bos taurus L.) grazing leafy, uniform swards in two separate studies. Grazing sessions were recorded on video, with the sound track originating from a forehead microphone. Each sound burst produced by a jaw movement was classified as a bite, chew or chew–bite. Jaw movements in these segments generated a virtually uninterrupted, regular succession of bite, chew and chew–bite sounds. Among individual animals, the variation in the rate of jaw movement was extremely low (Study 1: mean = 78.9 min −1 , CV = 6%; Study 2: mean = 77.9 min −1 , CV = 4%), but variation in the allocation of jaw movements was high (CV of proportion of jaw movements allocated to bites, chews and chew–bites = 58, 21 and 50%, respectively, for Study 1; 32, 12 and 32%, respectively, for Study 2). The proportions of chews and bites traded off directly against chew-biting. As the proportion of chew–bites increased, the number of jaw movements per bite declined and therefore the bite rate increased. Different combinations of the three types of jaw movement conformed to an isocline of a constant number of chew actions per bite (CV = 11 and 9% for Studies 1 and 2, respectively). Furthermore, this ratio was close to unity (1.27 and 1.24 chews per bite for Studies 1 and 2, respectively), and was similar for different levels of herbage mass in the range 145–255 g m −2 . The possible implications of these findings for the regulation of bite weight and diet quality are discussed.

Bite placement plays an important role in determining the mean weight of bites removed from a patch, and hence intake rate. This paper describes a video and acoustic methodology to map the sequential placement of bites on the sward surface. The methodology was evaluated for dairy heifers grazing small (0.34 m 2 ) patches of alfalfa ( Medicago sativa L.) to three levels of depletion (6, 18 and 30 bites). Grazing was recorded by a single video camera positioned 0.9 m in front of the animal and on average 1.67 m above the ground. Acoustic monitoring enabled the precise timing of biting jaw movements (bite or chew-bite). For each bite, a single video frame showing the position of the animal's head in the sward canopy was selected at the point in time corresponding to bite severance. Custom image-processing software was used to extract the image (apparent) coordinates of the tip of the muzzle, which was then converted geometrically to world (true) coordinates on the sward surface. A fixed displacement of 8 cm was applied to the world coordinates in order to determine the bite centre. The pattern of grazing impact across the sward surface was predicted by assuming a radius of impact around each bite centre. This pattern was compared with the measured status (grazed or un-grazed) of the herbage beneath each cell of a grid placed over the patch after grazing. Bite placement on the sward surface, as defined by the bite-centre coordinates, followed a progressing, side-to-side pathway. The median distance between the centres of consecutive bites was 12.1 cm, and was significantly less than expected by random bite placement. The orientation of consecutive bite pairs differed significantly from random, consistent with the side-to-side pathway of bite placement. Nevertheless, based on nearest neighbour analysis, the overall pattern of bite spacing on the surface of the sward did not differ significantly from random. These results suggest that the observed declining trend in mean effective bite area with increasing depletion ( P = 0.06) derived from inefficient exploitation of the sward surface. The assumption of a radius of impact of 6 cm revealed a broad correspondence between the measured and predicted patterns of grazing impact across the sward surface. Discrepancies most likely reflected sweeping actions of the tongue during bite formation, lateral head movements during bite severance and simplifying assumptions required by the single-camera approach. The results indicate that the methodology is potentially useful for investigating the rules governing bite placement in the horizontal plane.

Animals show impulsiveness when they prefer a smaller more immediate option, even though a larger more delayed option produces a higher intake rate. This impulsive behavior has implications for several behavioral problems including social cooperation. This paper presents two experiments using captive blue jays (Cyanocitta cristata) that consider the effects of payoff accumulation and temporal clumping on impulsiveness and cooperation. Payoff accumulation refers to a situation where the benefits gained from each choice trial accumulate from one trial to the next, and only become available to the animal after it has completed a fixed number of trials. We hypothesized that this would reduce impulsiveness because it removes the advantage of quickly realizing food gains. Clumping refers to situation in which the animal experiences several choice trials in quick succession followed by a long pause before the next clump. We hypothesized that if payoffs accumulated over a clump of trials this would enhance the effect of accumulation. We tested the effects of accumulation and clumping on impulsiveness in a self-control situation. We found a significant interaction between clumping and accumulation. Payoff accumulation reduced impulsiveness, but only when trials were clumped. Post hoc analyses suggest that clumping alone increases impulsiveness. A second experiment applied these results to cooperation. This experiment reveals an interaction between payoff accumulation and trial’s position within the clump. Jays were more likely to cooperate on the first trial of a clump, but the likelihood of cooperation dropped after the first trial. However, this drop was larger when payoffs did not accumulate. This observation suggests that the difference between accumulated and unaccumulated treatments that we reported previously (Science 198: 2216–2218) may be largely due to differences in how animals behave in the first trial of a clump. © 2005 Elsevier B.V. All rights reserved.

Field experimental studies on surge flow irrigation with sediment-laden water in northwestern China showed that a sealing layer was formed on the soil surface as a result of the sediments in the irrigation water going through a ‘trapping’, ‘settling’ and ‘sealing’ processes in the irrigated field. The sealing layer reduced the surface roughness and intake rate of the surface soil, and thus sped up the flow advance. Therefore, higher irrigation efficiency can be achieved with less irrigation water requirement. Analytical studies on water saving efficiencies indicated that the water saving effect of surge irrigation with sediment-laden water was achieved by an interactive impact of sediment content and the intermittent feature of surge flow, but the sediments effect was more pronounced.

International audience; Concerns about biodiversity preservation through grazing have revived interest in feeding choices made by herbivores. In this article, we study the dynamics of behavioural intake response in heterogeneous vegetation, where the size and quality of edible plants is highly diverse and varies from day to day as a result of grazing. We conducted two experiments with ewes grazing in paddocks located in shrubby rangelands. A direct in situ observation method was used, with continuous observation of ingestive bites taken by a continuously monitored individual. A bite coding-grid enabled us to distinguish the extreme diversity between bites masses and structure, including the ones resulting from plant depletion. Flock activities were also scan-sampled. Observations were made throughout complete paddocking sequences, which lasted for about two weeks. Grazing seriously depleted the paddocks since 75–95% of the herbaceous species was consumed. No trend was detected either in daily activity patterns or in intake time-budgets. These two variables were well synchronised between the continuously monitored individuals and their respective flocks. No inter-day trend was observed for dry matter daily intakes, which was twice higher than predictions from existing models on sheep intake. Our data enabled us to explore the relationship between the diversity of instantaneous feeding choices and the quantitative daily intake. On the instantaneous scale (20 s), we confirmed the functional relationship between bite mass and bite frequency. Little variation was observed in daily averages of ingestive behaviour components. But these averages hide the extremely large range of instantaneous values (from 0.04 to 1.2 g DM for bite mass). When vegetation size and structure declined as a result of grazing, the ewes progressively took larger bite masses with equivalent nutritive quality, thus adopting a pattern of consumption that is not consistent with the general assumption that such bites are chosen during the first day, as a result of the behavioural quantity–quality trade-off. This article provides knowledge about which type of diversity in plant parts size, structure and composition offers a small ruminant satisfying behavioural leeway in composing its meals and reaching physical satiety.We tend to discard pastoral management practices focused on biomass evaluation, and encourage further studies that will help qualify the nature and structure of vegetation that offers adjustment possibilities at both the individual and flock levels.

Lake Miyajimanuma, in central Hokkaido, is an important stopover site for white-fronted geese (Anser albifrons) wintering in Japan. In this area, increasing numbers of the geese are causing damage to wheat crops. The effects of several factors on the unconsumed density of food resources in rice fields, their main foraging site, were investigated with a view to propose a method for reducing damage. It is shown that unconsumed rice grain density increased with decreasing distance from houses, roads and windbreaks, which seemed to act as disturbance factors. Unconsumed rice density was also affected by the type of harvester used, probably because of the difference in net intake rate between the sites where different types of harvester operated. It is recommended that rice fields be harvested using the current machinery, and located further from houses, roads and windbreaks, wheat fields being located nearer to houses, roads and windbreaks.

International audience; The grazing process determines not only the nutrient intake of ruminants at pasture but also the intensity of their impact on vegetation. Grazing dynamics are the result of complex interactions between animal and sward characteristics. While sward is being depleted, a decline in intake rate is partly offset by longer grazing time. This behaviour may be controlled by nutritional feedback from digestion and nutrient absorption as the quality of the ingested herbage decreases. To simulate the dynamics of feeding behaviour and intake during sward exploitation, we developed a mechanistic model of intake rate that combines sward architecture and foraging decisions, and we linked this model with another focusing on control of intake. The sward was divided into horizons characterised by bulk density and nutritive value (NDF content and digestibility), enabling prediction of bite mass and potential intake rate for each grazed horizon. Animal decisions were simulated at two levels: (i) animal activity (eating, ruminating or resting) was self-regulated every minute by comparing a motivation-to-eat function with a satiation function based on a digestion and metabolic sub-model; (ii) while eating, the horizon to be grazed was decided through a choice function taking into account the relative availabilities and potential intake rates of the two upper horizons. The model simulates the animal-sward interactions from elementary parameters (bite mass, intake rate, etc.) to integrated outputs (sward height, daily intake, etc.). Hence, the interplay between characteristics of the vegetation and the internal state of the animal is dynamic taken from the level of a few bites to several successive days. Satisfactory validations were obtained on experimental data sets obtained in both rotational grazing with dry ewes and continuous grazing with lactating ewes. The sensitivity analysis highlights the balance between factors that control bite mass and intake rate and factors that control grazing time. Combining both series of factors in the same model represents significant progress in predicting intake at grazing in a mechanistic way. The model makes it possible to explore the balance between intake regulation by nutritional variables (animal needs and sward quality) and by the availability and structure of the sward. Finally, it is a promising tool to explore the sensitivity of the grazing process to characteristics of both sward (height, bulk density, nutritive value) and animals (weight, nutritional requirements, behavioural traits), and to management practices (stocking rate, rotational versus continuous grazing).

Thorn removal experiments quantified the effects of plant spinescence on the foraging efficiency of two mammalian browsers of similar body size, the indigenous bushbuck and the introduced domestic boergoat. Spinescence limited the intake rates of both browsers; the extent being influenced by the animal's feeding technique. Larger bite sizes and rates enabled the bushbuck to increase their intake rate from dethorned branches. Spinescence restricted the feeding style of boergoats. Following thorn removal they attained larger bite sizes, and therefore greater intake rates. Boergoats were intrinsically fast eaters and were more efficient than bushbuck when foraging on spinescent species.

The use of feed intake behaviour traits, obtained from electronic feeding stations, and feed intake curve parameters to genetically improve performance traits was analysed. Daily feed intake and feed intake behaviour of 5601 group-penned boars of two dam lines were recorded by electronic feeders in weeks 1, 3, 5, 7 and 9 during 10 weeks (100–170 d) on performance test. Additionally, performance test traits and parameters of an individually fitted linear-quadratic regression of feed intake on time on test, were available. A multiple trait animal model considering observed feed intake and feed intake behaviour at each test week as a different trait was used. Estimated heritabilities for feed intake and feed intake behaviour of the entire test period were 0.39, 0.46, 0.34, 0.44, 0.44 and 0.41 for daily feed intake, time per day, visits per day, time per visit, feed intake per visit, and feed intake rate, respectively. Heritabilities for behavioural traits in each test week were below estimates of entire test and showed lower variation, except for daily feed intake and time per day. Residual standard deviation of feed intake using linear-quadratic regression on time on test showed a moderate heritability of 0.22. Genetic correlations of feed intake behaviour traits indicate that number of visits per day was independent from growth performance, while time per day was genetically associated with average daily gain and daily feed intake (0.31 and 0.41). In contrast, visits per day and related traits such as time per visit and feed intake per visit were genetically correlated with residual standard deviation of linear-quadratic regression (−0.28, 0.31 and 0.39). Feed intake per visit in the seventh test week resulted in the highest genetic correlation (0.45) with residual standard deviation of the feed intake curve. This residual standard deviation and related traits will be of increasing interest for future breeding programs in order to obtain high performances in a wide range of environments.

Modern ageing theory is based on the observation that oxidative metabolism causes damage that results in a gradual loss of vitality, leading to senescence and death. If animals can oxidize only a given amount of substrate in a lifetime (i.e. the ‘metabolic time’ is allocated from a fixed budget), then behaviour may be aimed at maximizing benefits per unit of ‘metabolic time’ expended. We analyse the consequences of this view for two types of behaviour that are commonly expressed as rates with respect to clock time. Examples are given of locomotory behaviour in which the animals' preferred speeds are generally interpreted as a result of maximization of energetic efficiency. The same behaviour could be expected if animals were ‘speed maximizers’ with respect to metabolic time. Examples are given of foraging behaviour that is also best predicted on the basis of maximization of energetic efficiency. This makes sense only if energy is allocated from a fixed budget. However, foraging animals not only expend energy but also consume it so energy cannot be considered as being allocated from a fixed budget. The same behaviour could be expected if animals were ‘energy intake rate maximizers’ with respect to metabolic time. This makes sense if metabolic time is allocated from a fixed budget as suggested by ageing theory. The metabolic time concept can provide a crucial link between the optimum intensity of short-term behaviour and its long-term fitness consequences. We discuss the implications of this approach for the modelling of foraging behaviour. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

We determined breast milk concentration of polychlorinated dibenzo-p-dioxins (PCDDs)/polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in 24 mothers living in Korea, and assessed the maternal body burden based on PCDDs/PCDFs and PCBs concentrations in breast milk and an infant intake rate through breast-feeding based on their concentration in breast milk. PCDDs/PCDFs and PCBs levels in breast milk from primipara mothers were found to be higher than those from multipara mothers. For total PCDDs/PCDFs TEQ level, 2,3,4,7,8-PeCDD was the predominant congener, and the proportion of 2,3,7,8-TCDD was less than 3% of total PCDDs/PCDFs TEQ level. For PCBs TEQ level, PCB-126 was the predominant congener. Maternal body burden levels of PCDDs/PCDFs and PCBs based on their concentrations in breast milk were 268-622 TEQ ng. The daily dioxin intakes of mothers were predicted to be 0.78-2.18 TEQ pg/kg/day for PCDDs/PCDFs and 0.34-0.66 TEQ pg/kg/ day for PCBs. For the first year, the body burden of an infant was predicted to be 212 TEQ ng and the daily intake of an infant was predicted to be 85 TEQ pg/kg/day, assuming the mean dioxin-related compounds concentration (27.54 TEQ pg/g fat).

Meal patterns and rates of feed intake by grazing herbivores may be markedly different from those found in housed ruminants and monogastrics. Cumulative intakes over the evening meal (satiety curves) were measured using groups of sheep ( Ovis aries L.) grazing monocultures of white clover ( Trifolium repens L., cv. Kent Wild White) and ryegrass ( Lolium perenne L., cv. Parcour). Intake was measured by weighing ewes before and after grazing, with an allowance for insensible weight loss, for each of six groups in sequence; when grazing clover after 15, 30, 45, 60, 75 or >90 min and when grazing grass after 20, 40, 60, 80, 100 and >120 min. In each case, the sixth group was allowed to graze until a break of at least 6 min had occurred, which was taken to be an inter-meal as opposed to an intra-meal interval. Measurements were made on both herbage species using non-fasted control animals and animals that had been fasted for 24 h prior to measuring intake. Regressions of cumulative fresh and dry matter (DM) intakes against minutes of eating (excluding intra-meal intervals), constrained to pass through the origin, were best described by linear rather than curvilinear relationships. This showed that intake rates were constant within a meal. However, as the meal progressed, the number of intra-meal intervals increased and if these intervals were included in eating time, then the relationships were curvilinear with intake rate decreasing with time since the onset of the meal. The non-fasted animals had shorter meals than fasted animals and animals grazing clover had shorter meals than those grazing grass. The application of these results to intake control mechanisms is discussed.

The contribution of taste to the food choices of foraging rats was examined. Rats in a laboratory foraging paradigm searched for sequential opportunities to eat at two feeders containing chow-based food pellets that were plain or flavored with saccharin or citric acid. Pellets cost the same number of bar presses at both feeders. Saccharin adulteration had no effect on intake parameters. Citric-acid-flavored pellets were eaten more slowly and in smaller meals. If there was no alternative food, daily intake was slightly reduced. When the alternative food was plain, fewer meals and fewer pellets were taken of the citric-acid-flavored than plain pellets. When we gradually increased the price of the plain pellets at one feeder, while the price at the alternative feeder (which contained either plain or citric-acid-flavored pellets) remained low, the rate of eating (profitability) decreased at the higher-price feeder, and the rats shifted their intake toward the less-costly, more profitable pellets. We compared the relationship between the relative eating rate at each feeder and the relative meal size (or daily intake) at each feeder when the low-priced food was plain and when it was flavored with citric acid, and found no differences. This indicates that taste may influence choice via its effect on rate of intake.

Plant species present a complex array of biochemicals to herbivores that in conjunction with a plant's physical structure influence intake. Our objective was to determine the role of postinges- .

The effect of physiological state lactating vs. non-lactating (dry) on grazing behaviour and herbage intake by Holstein-Friesian cows was examined on grass pastures maintained at 5, 7 or 9 cm sward surface height (SSH), typical of those provided under continuous variable stocking management. Intake rates were estimated over periods of 1 h by weighing the animals before and after grazing, retaining the faeces and urine excreted, and applying a correction for insensible weight loss. Grazing behaviour during these periods and over 24 h was recorded automatically using sensors to measure jaw movements. Bite mass (BM) did not differ significantly between lactating and dry cows but decreased ( P −1 as overall mean SSH decreased from 9 to 5 cm. An increase ( P =0.040) in grazing jaw movement (GJM) rate, from 75.3 to 80.3 GJM min −1 , as SSH decreased, did not compensate for reductions in bite mass, and intake rate declined linearly ( P =0.006) from 24.6 to 18.9 g OM min −1 . Lactating and dry cows compensated for the reduction in intake rate, by increasing total grazing time and total number of bites per day. As SSH decreased from 9 to 5 cm, lactating and dry cows increased total eating time (528 to 607 and 419 to 510 min), total GJM (40 400 to 49 300 and 31 300 to 40 600 GJM) and total bites (31 100 to 37 900 and 24 600 to 31 200 bites, respectively). As a result, there was no significant effect of SSH on daily intake of OM, although lactating cows had greater intakes than dry cows; 12.9 vs. 9.3 kg day −1 , ( P P P =0.060), allowing them 120 to 160 min more idling (i.e., non-grazing, non-ruminating) behaviour ( P =0.001).

The AirPEx (air pollution exposure) model is a mathematical model to estimate the inhalatory exposure of humans to air pollution. The model quantifies individual and population exposures using data from air quality time series and activity pattern surveys. This paper presents the basic exposure concepts of the model, including contact, actual exposure concentration, intake rate, and standardisation. A case study including the exposure to ozone of the Dutch population in the 1991 summer demonstrates the application of the model.

In independent assays, workers of the ant Camponotus mus were conditioned to visit an arena where they found a large drop of sucrose solution of different concentrations, from 5 to 70% weight on weight (w/w). Single ants were allowed to collect the sucrose solution ad libitum, and feeding time, feeding interruptions, crop load, and intake rates were recorded. Feeding time increased exponentially with sucrose concentration, and this relationship was quantitatively described by the increase in viscosity with concentration corresponding to pure sucrose solutions. Ants collecting dilute solutions (5 to 15% w/w) returned to the nest with partial crop loads. Crop filling increased with increasing sucrose concentration, and reached a maximum at 42.6% w/w. Workers collecting highly concentrated solutions (70% w/w) also returned to the nest with a partially-filled crop, as observed for dilute solutions. Nectar intake rate was observed to increase with increasing sucrose concentration in the range 5 to 30% sucrose. It reached a maximum at 30.8%, and declined with increasing sucrose concentration. Results suggest that both sucrose concentration and viscosity of the ingested solution modulate feeding mechanics as well as the worker's decision about the load size to be collected before leaving the source.

Three year-old Sitka spruce saplings, which had received one of two levels of fertiliser addition (high or low) in one year, were either browsed by red deer or left undamaged in a subsequent year. After a further year of growth, the selection and browsing behaviour of red deer on damaged and undamaged trees were studied in a controlled experiment. Morphological and chemical analysis of ten trees from each treatment combination showed that damaged trees were significantly smaller after one year than undamaged trees but had longer needles. Chemical composition was not affected by browsing. High fertiliser addition increased most size parameters and increased the nutritive value of trees. The preference for previously damaged and undamaged trees was compared in a series of thirty two trials. On eight separate occasions, four red deer hinds were individually offered the choice of two damaged and two undamaged trees in an experimental enclosure. During each trial, biomass removed, number of bites removed, duration of browsing, intake rate, and mean bite weight at each tree were recorded. Biomass removed, bites taken and time spent at trees were significantly greater for previously undamaged trees than for damaged trees. All three variables were also positively related to the height of each tree and the number of lateral branches on each tree. The greater foraging effort on undamaged trees was not fully accounted for by the morphology of trees or their chemical composition. It is suggested that increased needle length caused animals to stop feeding sooner and hence led to less browsing damage in previously damaged trees. The results imply that previously observed localised browsing damage in forestry plantations is unlikely to be the result of changes to the plant induced by previous browsing damage.

Brown trout were exposed to 32 P in their tank water (7.4 Bq l −1 ) and the uptake to muscle followed over 6 weeks. A steady-state concentration factor (C ss ) of 1.7 and a biological half-time for clearance ( t b 1 2 ) of 45 days were calculated from the results. The low C ss indicates that uptake from water is not a major route of 32 P accumulation in these fish. Brown trout were given a single 32 P-spiked meal, and the uptake and clearance in muscle, liver and blood followed over 6 weeks. Assimilation of the isotope by these organs was low, the maximum activity in whole muscle reaching only 0.2–0.4% of that in the meal with lower values in the other two organs. There was no appreciable clearance of 32 P from muscle during the experiment. The slow clearance of 32 P after uptake from water and lack of any clearance after uptake from food indicates that the C ss for this isotope following uptake by either route is likely to depend on radioactive decay rather than intake rate and physiological clearance.

Relative food patch size and inter-patch distance are assumed to be important factors affecting the extent of within-group feeding contest competition among primates. The present study on wild female Japanese macaques revealed the occurrence of within-group feeding contest competition for their main winter food item, seeds of Zelkova serrata , and showed that the rank-related difference in feeding behaviour increased when available Zelkova patches were small relative to the area of group dispersion. Low-ranking females did not feed in small and isolated patches of Zelkova , switching instead to inferior food items in terms of energy intake rate, which led to an overall rank-related difference in feeding success. Small and isolated Zelkova patches contained more neighbours and high-ranking females, and fewer low-ranking females, than large and contiguous patches. The frequency of submissive behaviour rose when the density of neighbours increased. Food characteristics that may affect the extent of within-group contest competition are discussed.

Twenty-four mature, dry, female goats were grazed on Brachiaria -dominated pasture to study the effects of tethering on intake. Animals were either tethered for 4 h (T4) or 8 h (T8), or grazed freely for 8 h (FG) during a 28 day period. Intake was estimated by two methods: (1) short-term BW changes and (2) n -alkanes as internal markers. The BW technique was suitable for conditions in developing countries, although correction factors for changes in bite rate through the grazing day may be needed in order to estimate total intake. The alkane technique may be more appropriate to estimate total intake, but it involves sophisticated and expensive chemical analyses. Animals grazed for 4 h had similar total daily intakes to those grazed for 8 h: 1055 g day −1 , 1183 g day −1 and 1259 g day −1 for T4, T8 and FG treatments, respectively. The T4 animals compensated for the shorter time available by increasing intake rate and spending a larger proportion of available time eating. Although the reason for higher intake rates observed in T4 animals was unclear, duration of fasting was not considered to be a factor. Lower intake rates observed at the end of the day for tethered animals may have resulted from decreasing herbage mass availability and soiling. Free-grazed animals did not alter intake rate and had total intakes that did not differ from those of T8 animals. Increased rates of intake might be expected to increase rate of passage and decrease digestibility; however, in the present trial, digestibilities (0.49, 0.54 and 0.51 for T4, T8 and FG animals, respectively) did not differ ( P > 0.05) among treatments. The results showed no serious disadvantage in terms of intake and digestibility, either of tethering per se, or of tethering for 4 h as opposed to 8 h, for mature non-productive goats, which were able to alter behaviour to compensate for limited time available for grazing.

The producer–scrounger model of Barnard & Sibly (1981,Anim. Behav.,29,543–550) predicts that at a certain ratio of producers and scroungers in a foraging group the payoff curves for individuals of the two phenotypes intercept. At this point all the group members obtain equal payoffs. In this paper, the original model is elaborated further by allowing individuals to differ not only in their food-finding abilities but also in their abilities to compete for the food once it is found. As in Barnard & Sibly's original model foraging individuals are assumed to share information about the whereabouts of food patches and to benefit from patches found by others. Here it is determined under which combinations of searching and sharing characters food intake rate in mixed-phenotype groups would be equal for producing and scrounging individuals. In the present model the payoffs are much affected by both the finder's advantage (the fraction of prey available only to the finder of the food-patch) and the combination of the foraging characters of the two phenotypes. Generally the intake rate of producers increases with their presence in the group and with increases in the finder's advantage. Our model suggests that the equal payoffs arise only when the relative food-searching and competitive abilities of producers and scroungers fall within a narrow range of options acknowledging also the finder's advantage. Moreover, such combinations are predicted to be unstable if only foraging benefits are called for in group formation, this being a common feature of social foraging models incorporating foraging role asymmetries.

The daily forage intake of ruminants is made up of a series of meals. These meals are especially pronounced in animals fed in stalls and coincide with the distribution of food. A relatively simple model of ruminant digestion was developed and used to test equations designed to predict rate of forage intake during meals. An equation that had been published previously as a means of controlling daily dry matter intake was combined with a Michaelis equation to control intake rate as the integrated hunger signal from chemostatic and distension feedbacks varied. The termination of the meal was based on experimental observation and the status of the model was examined for indications of the satiety mechanism at the end of the meal. The predicted level of hunger at the end of the meal varied. It is proposed that the end of the meal is triggered by an integrated hunger and palatability signal and two simple products are suggested by the data; however, the problem is likely to require a more complex function.

The effects of sward structure and bite weight ( W ) on bite rate in cattle ( Bos taurus ) were examined to explain the behavioural components of handling time. Three oesophageally fistulated steers grazed homogeneous, hand-constructed swards of Paspalum dilatatum Poir. or Medicago sativa L., in a sward area of approximately 0.36 m 2 , for 60–212 s. Three types of jaw movements (JM) were distinguished: manipulative JM that gather herbage into the mouth, chewing JM, and compound JM that manipulate fresh herbage and chew herbage already in the mouth within one cycle of opening and closing of the jaws. Intake rate ( I , g min −1 ) was a discontinuous asymptotic function of W: I = W max (0.0337,0.0201 + 0.0095 ∗ W) . Sward height and bulk density did not significantly affect I beyond the effects of W . Time per bite was 2.0 s when W ≈ 1.29 g, and increased linearly with W when W >1.29 g. Linear regression of time per bite on total number of JM explained 96% of the variance. A non-linear relation between total JM per bite and W comprised a linear relation between total chews per bite and W , and a constant number of total manipulative JM per bite. When W increased up to c . 1.5 g, chewing requirements were met by compound JM. Above W of 1.5 g, the overlap of chewing and manipulation reached a maximum, so total JM increased with W . The importance of compound JM and the potential for overlap between chewing and searching are discussed in the context of foraging models.

We suggest a theoretical framework for predicting the distribution of predators when interference between predators is insignificant but depletion of the prey population is important. The pattern of density-dependent mortality of the prey can then be predicted. By incorporating the intake rate at which predators starve or emigrate we can determine the predator density a locality can sustain. We use this framework to show how it is possible to predict the change in predator population at a locality resulting from habitat loss.