Number Of Feeding Bouts Research Articles

Comparison of single- and double-spaced feeders with regard to damaging behavior in pigs.

This work compared the behavior and performance of 24 groups of 12 pigs kept in pens with either a DOUBLE [one feed space aligned with the front wall of the pen (WALL), and one immediately adjacent (IN)] or SINGLE (WALL only) spaced feeder, from weaning until slaughter. Pens were equipped with a rack of fresh grass and a rubber toy (weaning phase) or a wooden board (finishing phase). Every 2 weeks, interaction with the enrichment, aggressive, harmful, and play behaviors were recorded for 5 min, four times a day. In addition, the pigs were individually assessed every 2 weeks for ear, tail, and flank injuries using a 4-point scale. The duration of feeder occupancy, feed space occupancy, number of and duration of feeding bouts, and aggressive behavior at the feeder were recorded continuously from video recordings (two times while in the weaner stage and two times while in the finisher stage, one camera/pen; 1 h per occasion). Individual body weight was recorded at weaning, transfer, and slaughter, and feed delivery was recorded daily at the pen level; from these measurements, average daily gain, feed intake, and feed conversion ratio were calculated. Data were analyzed using SAS v9.4. There was no effect of treatment on damaging behaviors. Pigs in DOUBLE had worse tail lesion scores on 6 of the 9 recording days (P < 0.001), but values rarely exceeded 1. Total feeder occupancy tended to be longer in DOUBLE than in SINGLE (P = 0.06). DOUBLE selected the IN feed space more often than WALL regarding the number of feeding bouts (P < 0.001). During feeding, pigs in DOUBLE received fewer aggressive behaviors than SINGLE (P < 0.001) and experienced fewer displacements than SINGLE (P < 0.001). Although both experimental groups had a similar weight at slaughter (P > 0.05), the FCR was lower in DOUBLE than in SINGLE (P < 0.05). These data suggest that doubling space at the feeder to two spaces/12 pigs reduced aggression and displacement behaviors at the feeder, indicating less competition for food. However, increasing feeder space was not a management strategy that could ensure reduced tail biting on commercial pig farms.

Effects of the dopamine depleting agent tetrabenazine on detailed temporal parameters of effort-related choice responding.

The dopamine-depleting agent tetrabenazine alters effort-based choice, suppressing food-reinforced behaviors with high response requirements, while increasing selection of low-cost options. In the present experiments, rats were tested on a concurrent fixed ratio 5/chow feeding choice task, in which high-carbohydrate Bio-serv pellets reinforced lever pressing and lab chow was concurrently available. Detailed timing of lever pressing was monitored with an event recording system, and the temporal characteristics of operant behavior seen after 1.0 mg/kg tetrabenazine or vehicle injections were analyzed. Tetrabenazine shifted choice, decreasing lever pressing but increasing chow intake. There was a small effect on the interresponse-time distribution within ratios, but marked increases in the total duration of pauses in responding. The postreinforcement-pause (PRP) distribution was bimodal, but tetrabenazine did not increase the duration of PRPs. Tetrabenazine increased time feeding and duration and number of feeding bouts, but did not affect feeding rate or total time spent lever pressing for pellets and consuming chow. Thus, TBZ appears to predominantly affect the relative allocation of lever pressing versus chow, with little alteration in consummatory motor acts involved in chow intake. Tetrabenazine is used to model motivational symptoms in psychopathology, and these effects in rats could have implications for psychiatric research.

Assessing the effect of rate and extent of starch digestion in broiler and laying hen feeding behaviour

Feeding behaviour can be affected by diet composition as a result of diet density, the rate and extent of ingredient digestion and the activation of nutrient sensing mechanisms. It was hypothezised that the presence of starch in the distal small intestine would activate the ileal brake, thereby increasing satiety, and changing feeding behaviour. Two semi-purified starch sources with differing in-vitro digestibility, wheat (WS, rapidly digested), and pea (PS, slowly digested), were used in four diets containing equal amounts of starch, but differing in WS/PS ratios (100/0, 80/20, 60/40, 0/100). Diets were fed to Ross 308 male (944) and female (1056) broilers housed in 32 litter floor pens from 0 to 28 d. Similar diets were fed to 192 laying hens from 26 to 46 weeks of age, housed in 16 experimental units, comprised of two conventional cages each. Video recordings (24 h) were taken at 27–28 d from four individually marked broilers per pen, and at 46 weeks of age from two hens per experimental unit. Focal observations were used to record the initiation and end of every feeding (broilers, hens) and drinking bout (broilers) over 24 h to calculate number of bouts, bout length, time between bouts, total time during the photo and scotoperiod, and time until first night bout. Data were analyzed as a four (diet) by two (gender) factorial arrangement (broiler) or one-way ANOVA (laying hen) using the SAS 9.4 GLIMMIX procedure. No interactions were found. Diet affected broiler number of visits to the feeder (P = 0.034), as well as time between feeding bouts (P = 0.031) and total feeding time (P = 0.028), but changes appeared random and did not support a satiety hypothesis. Males had more visits to the feeder (P < 0.001) and more total feeding time (P < 0.001) than females, but shorter feeding bout length (P < 0.001), suggesting increased hunger. Drinking behaviour was not affected, except for a longer time between bouts for females (P = 0.046). No effect of diet on day-time hen feeding behaviour was found, but the number of feeding bouts during the scotoperiod increased (P = 0.029) and time to the first night feeding event decreased (P < 0.001) as PS increased, suggesting increased hunger with PS level. In summary, no effect of dietary PS on broiler feeding behaviour was found. However, dietary effects on hen night feeding behaviour suggest that PS increased hunger, in contrast to the hypothesis.

Nitric oxide and l-arginine regulate feeding in satiated rats

Nitric Oxide (NO) and its precursor l-arginine were found to inhibit feeding in rats with a low motivation to eat, as they do in Aplysia. In rats that are relatively satiated, treatment with an NO blocker increased feeding, and treatment with an NO donor or with either of 2 doses of l-arginine inhibited feeding. NO and l-arginine modulated several parameters of feeding, such as the total duration of appetitive behaviors, the time spent feeding, the quantity of food eaten and the number of feeding bouts. The inhibitory effect of l-arginine on feeding could not be attributed to changes in locomotion. These data indicate that satiation is partially mediated by increased production of NO. NADPH-Diaphorase histochemical staining, which is specific for tissues actively producing NO, showed significantly greater staining in satiated compared to hungry rats in all 4 hypothalamic nuclei (paraventricular and arcuate nuclei, lateral and ventromedial hypothalamus) that were examined. l-arginine may act as a regulator of feeding by controlling NO production in several hypothalamic nuclei, specifically under condition of a low feeding motivation.

A hidden Markov model to estimate the time dairy cows spend in feeder based on indoor positioning data

The feeding time of dairy cows is linked with the health status of the animal and can be used to estimate daily feed intake together with other measurements. The aim of this study was to develop a model to measure the time a dairy cow spends at a feed bunk using an Ultra wide-band indoor positioning system.The feeding behavior of 50 dairy cows was measured during 7 days using Ubisense indoor positioning system and Insentec roughage feeders. The feeding probability (presence at the feeder) of the cows was calculated using logistic regression model with the distance to feed barrier as input and the Viterbi algorithm was used to calculate the most likely state (feeding or not feeding) given state transition probabilities.The model was able to predict whether the cow was at the feeding trough or not with the accuracy of 97.6%, sensitivity 95.3% and specificity 97.9%. The model was also able to estimate the mean bout duration and the number of feeding bouts.

The effect of trough space and floor space on feeding and welfare of lambs in an intensive finishing system

This study examined the effects of floor space and feeder space on the feeding behaviour, growth and stress physiology of lambs, at different times, over a 6-week period in a finishing feedlot. A total of 640 lambs in four time replicates (160 lambs per replicate) were studied in four 40-lamb intensive finishing systems (feedlots) for 6 weeks over a 16-month period. The lambs were Merino wethers with live weight at the commencement of the experiment of 28.3 (s.d.=2.4)kg. The effects of two factors, pen floor space (2 and 5m2/lamb) and feed trough space (4 and 10cm/lamb) were examined in a factorial arrangement. Measurements taken on individual lambs during the experimental period included: feeding behaviour and displacements at the feeder in the feedlot during weeks 1, 2 and 6, lying behaviour during week 3, weekly live weights and cortisol concentrations in weeks 1 and 6. Weekly feed intake for each group of lambs was also record. Trough space of 4cm compared to 10cm per lamb reduced average lamb feed intake in all weeks of the 6-week period (a reduction of 1.2 (s.e.=0.53) kg/hd in week 1, 1.3 (s.e.=0.62)kg/hd in week 2, weekly average of 0.9 (s.e.=0.17)kg/hd over weeks 3–6; P=0.05, P=0.06 and P=0.0004, respectively). However, weight gain only differed significantly during the first week in the feedlot (average of 0.2 vs 1.1 (s.e.d.=0.35)kg for 4cm vs 10cm/lamb of provided trough space, P=0.03). At all observed times within the 6-week period, lambs with the reduced feed trough space spent less total time feeding (P<0.05) with less feeding bouts (P<0.05). There was no effect of feed trough space on lying time or cortisol concentrations. Floor space did not affect feeding and lying behaviour, feed intake, weight gain or cortisol concentrations. In conclusion, increasing feed trough space from 4 to 10cm/lamb increased feed intake and live weight gain through an increase in the number of feeding bouts and the total time feeding. This indicates that the trough space recommendations in the Australian Model Code of Practice (sheep) of 2cm/lamb are too low for maximum lamb feed intake and live weight. No effects of increasing floor space from 2 to 5m2/lamb were found, however the growth rates in general were low suggesting that the environment in the feedlot may have been sub-optimal.

Relationships between temperament, feeding behaviour, social interactions, and stress in lambs adapting to a feedlot environment

The production of lamb meat is a large and important industry in Australia. Variability and seasonality of the climate and the demand for a consistent product (in terms of weight and age) have led to an increase in the use of feedlot systems for finishing lambs. While most lambs acclimatise to this environment, an estimated 5–20% may suffer from inanition or shy feeding, but there is little direct information available on associated physiological stress. This exploratory study examined relationships between temperament, feeding behaviour, social interactions and cortisol concentrations in lambs in the first 2 weeks in an intensive finishing system (feedlot). Lambs in two 20-lamb feedlots (with 2m2 floor space/animal) were studied. Prior to entry to the feedlot, the lambs were subjected to a temperament test (Isolation Box Test) in which activity was measured. Weight gain, general activity, lying time, time at the feeder, number of feeding bouts, displacement at the feeder and plasma cortisol concentrations in weeks 1 and 2 in the feedlot were recorded. A parsimonious general linear model was developed to relate the logarithm of cortisol concentration in weeks 1 and 2 to all other measurements. In week 1 cortisol was most elevated if the lamb’s activity in the feedlot (number of steps) was low (P=0.000025) and also for those lambs that fed more frequently (P=0.0010). Higher levels of activity in the temperament test were associated with higher cortisol concentrations in week 1 when the lamb was not displaced from the feeder. However there was an interaction with the number of displacements (P=0.0016), leading to little effect when a displacement occurred. In week 2 higher cortisol concentrations were associated with higher growth (P=0.040) which may be a reflection of the positive association between cortisol and feeding bouts in week 1. This study demonstrates relationships between cortisol concentrations, activity in the temperament test, feeding bouts, displacements at the feeder and activity in the first week and growth in the second week in the feedlot. A better understanding of these behaviour and stress relationships early in the feedlot may be useful in identifying strategies to protect vulnerable animals in feedlots.

A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees (Bombus terrestris).

Generalist pollinators like the buff-tailed bumble bee, Bombus terrestris, encounter both nutrients and toxins in the floral nectar they collect from flowering plants. Only a few studies have described the gustatory responses of bees toward toxins in food, and these experiments have mainly used the proboscis extension response on restrained honey bees. Here, a new behavioral assay is presented for measuring the feeding responses of freely-moving, individual worker bumble bees to nutrients and toxins. This assay measures the amount of solution ingested by each bumble bee and identifies how tastants in food influence the microstructure of the feeding behavior.The solutions are presented in a microcapillary tube to individual bumble bees that have been previously starved for 2-4 hr. The behavior is captured on digital video. The fine structure of the feeding behavior is analyzed by continuously scoring the position of the proboscis (mouthparts) from video recordings using event logging software. The position of the proboscis is defined by three different behavioral categories: (1) proboscis is extended and in contact with the solution, (2) proboscis is extended but not in contact with the solution and (3) proboscis is stowed under the head. Furthermore the speed of the proboscis retracting away from the solution is also estimated.In the present assay the volume of solution consumed, the number of feeding bouts, the duration of the feeding bouts and the speed of the proboscis retraction after the first contact is used to evaluate the phagostimulatory or the deterrent activity of the compounds tested.This new taste assay will allow researchers to measure how compounds found in nectar influence the feeding behavior of bees and will also be useful to pollination biologists, toxicologists and neuroethologists studying the bumble bee's taste system.

A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees (&lt;em&gt;Bombus terrestris&lt;/em&gt;)

Generalist pollinators like the buff-tailed bumble bee, Bombus terrestris, encounter both nutrients and toxins in the floral nectar they collect from flowering plants. Only a few studies have described the gustatory responses of bees toward toxins in food, and these experiments have mainly used the proboscis extension response on restrained honey bees. Here, a new behavioral assay is presented for measuring the feeding responses of freely-moving, individual worker bumble bees to nutrients and toxins. This assay measures the amount of solution ingested by each bumble bee and identifies how tastants in food influence the microstructure of the feeding behavior. The solutions are presented in a microcapillary tube to individual bumble bees that have been previously starved for 2-4 hr. The behavior is captured on digital video. The fine structure of the feeding behavior is analyzed by continuously scoring the position of the proboscis (mouthparts) from video recordings using event logging software. The position of the proboscis is defined by three different behavioral categories: (1) proboscis is extended and in contact with the solution, (2) proboscis is extended but not in contact with the solution and (3) proboscis is stowed under the head. Furthermore the speed of the proboscis retracting away from the solution is also estimated. In the present assay the volume of solution consumed, the number of feeding bouts, the duration of the feeding bouts and the speed of the proboscis retraction after the first contact is used to evaluate the phagostimulatory or the deterrent activity of the compounds tested. This new taste assay will allow researchers to measure how compounds found in nectar influence the feeding behavior of bees and will also be useful to pollination biologists, toxicologists and neuroethologists studying the bumble bee's taste system.

Influence of manure scrapers on dairy cows in cubicle housing systems

Manure scrapers are widely used in dairy cow loose-housing systems. In order to evaluate the effects of the scrapers on the cows, we assessed their impact on the animals' cardiac activity, feeding behaviour, and the behavioural reactions of cows confronted with different types of scrapers. In part I of the study, we measured cardiac activity (mean R–R interval and RMSSD, a parameter of heart-rate variability) whilst observing the behaviour of 29 focal cows on three farms during situations with and without active manure scrapers. Lower RMSSD values were observed during scraping events while cows were either lying, standing or walking in the alleyway, standing completely in the lying cubicle, or standing half in the lying cubicle (P=0.03), but only tended to differ while directly confronted with the scraper (P=0.06). This indicates that dairy cows experienced at least some mild stress during manure-scraping events. In part II, the feeding behaviour of 12 cows on each of two farms was recorded by means of a jaw-movement sensor and compared between situations with the manure-scraping event following forage provision either within or outside the main daily feeding period (i.e. within 1 or after 2h from forage provisioning, respectively). The duration of night-time feeding (P=0.049) and the number of feeding bouts (P=0.036) were higher when a manure-scraping event took place within the main daily feeding period, indicating that the cows' feeding behaviour had been disturbed. In part III, we observed the cows' behaviour on 15 farms during eight manure scraping events per farm, where each of five farms had one of three different scraper types. We assessed the cows' immediate reactions when confronted with the scraper. In addition, we recorded the number of animals present in the alleyways before and after the manure-scraping events. The more cows that were present in the alleyways before the scraping event, the lower the proportion of cows showing direct behavioural reactions both with (P=0.017) and without (P=0.028) scraper contact, and the higher the number of cows that left the alleyways (P<0.001). Scraper type did not influence the proportion of cows showing behavioural reactions.In conclusion, our results show that dairy cows perceive the manure-scraping event negatively in some situations, that feeding behaviour may be disturbed when scrapers are active during the main feeding period, and that cows avoid the scraper during crowded situations.

Influences of Plant Toxins and Their Spatial Distribution on Foraging by the Common Brushtail Possum, a Generalist Mammalian Herbivore

Generalist herbivores forage on a variety of plant species, allowing them to gain nutrients while limiting ingestion of harmful toxins. As the capacity to mix diets appears important for maximizing intake, the spatial scale in heterogeneity of food resources should influence the foraging behavior of herbivores. Our aim was to identify how the feeding strategy of a generalist mammalian herbivore, the common brushtail possum, responds to foods within a spatially defined environment. We evaluated foraging responses against increasing spatial separation between pairs of artificial diets that differed in flavor and toxin profile, to determine how distance and diet affect intake and behavior. Foraging responses were influenced by the type of diet or the degree of spatial separation between foods but not by their interaction. Diet influenced intake, time spent feeding, and feeding rate, but had no effect on nightly foraging interval, number of feeding bouts, or bout length. The number of switches between paired food resources and foraging efficiency (intake per unit distance, which accounts for the energetic costs of travelling), were influenced only by distance. Titrating foraging against a range of distances demonstrated how quickly foraging efficiency can decline in response to the spatial separation of food resources, highlighting the importance of spatial heterogeneity of plants within the home range of an herbivore.

Amount of Plant Foods Eaten and Sexual Differences in Feeding among Wild Chimpanzees (Pan troglodytes) of Kanyawara Community

The amount of plant foods eaten and sexual differences in food intake among chimpanzees in Kibale Forest was investigated between July 2007 and January 2008. Continuous focal animal sampling was used to collect data on the diet, number, and duration of feeding bouts of 18 individuals of the Kanyawara chimpanzee community. Chimpanzees utilized 42 plant species for fruits, leaves, and piths. Among plant parts eaten, fruits contributed the greatest percentage of fresh weight (18) in the diets compared to leaves (5.1) and piths (3.6). The duration of feeding bouts varied, ranging from 1.5 to 45.8 minutes. When Mimusops bagshawei fruits were eaten, the numbers of feeding bouts per chimpanzee per day were high compared to when they were not. While our study agrees with previous studies that females spend more time feeding per day, it shows that the long feeding time among females does not translate to increased food weight. We suggest that the social role of females in taking care of the young and their attention being taken up by this role while feeding and fears associated with male presence is the reason for long feeding time among females.

Liraglutide improves hippocampal synaptic plasticity associated with increased expression of Mash1 in ob/ob mice

Consumption of high-fat diet exerts adverse effects on learning and memory formation, which is linked to impaired hippocampal function. Activation of glucagon-like peptide-1 (GLP-1) signalling ameliorates detrimental effects of obesity-diabetes on cognitive function; however, mechanisms underlying these beneficial actions remain unclear. This study examined effects of daily subcutaneous treatment with GLP-1 mimetic, Liraglutide, on synaptic plasticity, hippocampal gene expression and metabolic control in adult obese diabetic (ob/ob) mice. Long-term potentiation (LTP) induced by area CA1 was completely abolished in ob/ob mice compared with lean controls. Deleterious effects on LTP were rescued (P<0.001) with Liraglutide. Indeed, Liraglutide-treated mice exhibited superior LTP profile compared with lean controls (P<0.01). Expression of hippocampal brain-derived neurotropic factor and neurotrophic tyrosine kinase receptor-type 2 were not significantly different, but synaptophysin and Mash1 were decreased in ob/ob mice. Treatment with Liraglutide over 21 days increased expression of Mash1 in ob/ob mice (2.0-fold; P<0.01). These changes were associated with significantly reduced plasma glucose (21% reduction; P<0.05) and markedly improved plasma insulin concentrations (2.1- to 3.3-fold; P<0.05 to P<0.01). Liraglutide also significantly reduced the glycaemic excursion following an intraperitonal glucose load (area under curve (AUC) values: 22%; P<0.05) and markedly enhanced the insulin response to glucose (AUC values: 1.6-fold; P<0.05). O2 consumption, CO2 production, respiratory exchange ratio and energy expenditure were not altered by Liraglutide therapy. On day 21, accumulated food intake (32% reduction; P<0.05) and number of feeding bouts (32% reduction; P<0.05) were significantly reduced but simple energy restriction was not responsible for the beneficial actions of Liraglutide. Liraglutide elicits beneficial effects on metabolic control and synaptic plasticity in mice with severe obesity and insulin resistance mediated in part through increased expression of Mash1 believed to improve hippocampal neurogenesis and cell survival.

Frugivory by five bird species in agroforest home gardens of Pontal do Paranapanema, Brazil

The inefficiency of conservation efforts based exclusively on natural habitat patches has called the attention of some conservationists to the matrix. Described as the major component of a landscape, the matrix is often agricultural, particularly in the tropics. In this context, agroforestry practices have been recognized for their ability to support a rich fauna and flora. Besides the extensive literature concerning bird communities in agroforestry systems, very few studies analyze how different species respond to the management of such practices. Our study describes the diet and habitat use frequency of five frugivorous bird species in agroforest home gardens, secondary forests, and pastures in the region of Pontal do Paranapanema, Brazil. The focal species were Ramphastos toco (Toco Toucan), Pteroglossus castanotis (Chestnut-eared Aracari), Amazona aestiva (Blue-fronted Amazon), Ara chloroptera (Green-winged Macaw), and Cyanocorax chrysops (Plush-crested Jay). We gathered both habitat use frequency and diet using the “feeding-bout” method. Overall frequency was higher in the secondary forest when compared to pasture and home gardens for all bird species except A. aestiva. The number of feeding bouts was higher in home gardens than in forests for all species with the exception of C. chrysops. Differences in monthly median feeding activity were only statistically significant for C. chrysops and for A. aestiva. The latter was the only species observed feeding in pasture habitats. The total number of food taxa was larger in home gardens than in the forest. Our results reinforce the importance of agroforestry systems as a resource-rich habitat for frugivorous birds.

Implications of food patch distribution on social foraging in domestic pigs (Sus scrofa)

Feeding behaviour of social animals can be influenced by the spatial distribution of resources. In domestic housing facilities growing pigs will often be fed from feeding sites confined to a small area, i.e. effectively a clumping of food resources. In the present experiment we investigated how feeding behaviour of growing pigs changed with increasing distance between feeding sites. During 20-min feeding tests, eight groups, each consisting of four growing pigs (35.4±2.7kg), were allowed to eat from four buckets containing food pellets placed in a test arena in a rectangular pattern. The positions of the buckets, determined by their mutual distance, were close (15–25cm), medium (245–290cm) or far (460cm). Feeding behaviour of the pigs was video recorded. There was a significant effect of feeding site position on all variables investigated except for the number of displacements from food buckets (i.e. time spent eating, intake, number of bouts, mean bout duration, number of aggressive interactions, number of shifts to new feeding sites: P<0.0001; mean duration of aggressive interactions: P=0.0010; displacements: P=0.3228). Physical separation of food sites (medium and far) affected aggressive interactions (lower frequency, longer mean duration) compared to minimal separation (close). Time spent eating, number of feeding bouts, number of shifts to a new site, and food intake decreased with increasing distance between food sites (from close to far). Mean bout duration was affected by physical separation of, but not distance between, feeding sites. These results indicate that feeding behaviour is markedly different when resources are clumped and even a small separation of troughs can profoundly alter patterns of aggressive behaviour and feeding.

Experimental tail elongation in male Barn SwallowsHirundo rusticareduces provisioning of young, but only in second broods

At the beginning of the breeding season, the outermost tail feathers of 31 male Barn SwallowsHirundo rusticawere either shortened by 20 mm, elongated by 20 mm or left unmanipulated. In first broods, the number of feeding bouts (per nestling per hour) by males and females did not differ significantly among experimental groups. However, in second broods, males with elongated tails fed their nestlings less often than males with shortened or unmanipulated tails. Male tail elongation may have been detrimental to flight, making capture of insects more difficult. Females paired to long‐tailed males did not compensate for this reduction in feeding by males and their nestlings received less food. Neither feeding rates nor brood size differed significantly between first and second broods. Variation in abundance of large insects at different times of the day (high around noon and low in the morning and afternoon) matched variation in feeding rates, supporting the importance of large insects in the Barn Swallow diet. Different feeding rate patterns in first and second broods by males with elongated tails could have at least three explanations: (1) such males were able to adjust their parental effort to some extent, temporarily compensating for an imposed handicap; (2) they were more sensitive than males in the other experimental groups to late season food shortage (a decrease in numbers of large insects, the main Barn Swallow prey, was observed as the season progressed); and (3) they were more sensitive than males in the other experimental groups to the deterioration in their physical condition after first broods.

Sideroxylonal in Eucalyptus foliage influences foraging behaviour of an arboreal folivore

Plant secondary metabolites (PSMs) offer plants chemical defences against herbivores, and are known to influence intake and diet choice in both insect and mammalian herbivores. However, there is limited knowledge regarding how PSMs influence herbivore foraging decisions. Herbivore foraging decisions, in turn, directly impact on which individual plants, and plant species, are selected for consumption. We took advantage of the natural variation in sideroxylonal concentrations in the foliage of Eucalyptus melliodora (Cunn. ex Schauer) to investigate feeding patterns of a marsupial folivore, the common ringtail possum, Pseudocheirus peregrinus (Boddaert 1785). Foliage, collected from six trees, contained between 0.32 and 12.97 mg g-DM(-1) sideroxylonal. With increasing sideroxylonal concentrations, possums decreased their total intake, rate of intake and intake per feeding bout, and increased their cumulative time spent feeding. Possums did not alter their total feeding time, number of feeding bouts or time per feeding bout in response to increasing sideroxylonal concentrations. Results demonstrate important behavioural changes in foraging patterns in response to sideroxylonal. These behavioural changes have important implications, in relation to altered foraging efficiency and potential predation risk, for herbivores foraging in the field. As a result, the spatial distribution of dietary PSMs across a landscape may directly influence herbivore fitness, and ultimately habitat selection of mammalian herbivores.

Threonine-imbalanced diet alters first-meal microstructure in rats

Diets limiting in an essential amino acid have long been known to suppress food intake. The purpose of this study was to examine the microstructure of feeding behavior of rats within the very first meal of an imbalanced diet. Rats were preconditioned for 12 days on a Baseline diet and were then given a test diet with either a corrected amino acid profile or a diet imbalanced with respect to the essential amino acid threonine. Overall, first-meal intake and first-meal duration were robustly and significantly reduced by the Imbalanced diet but not altered by the Corrected diet. The Corrected diet caused an increase in the number of feeding bouts during the first meal. The Imbalanced diet increased the duration of pauses during the first meal. Most rats in the Imbalanced group stopped eating after just 15 min of exposure to the diet, but those still eating after this time tended to have a lower rate of eating compared to those eating the Corrected diet. On the basis of these results, we conclude that changes in microstructure and meal duration contribute to the reduction in food intake upon exposure to amino-acid-deficient diets.

Effect of level of inclusion and method of presentation of a single distillery by-product on the processes of ingestion of concentrate feeds by horses

The eating behaviour of horses offered wheat distiller grains at varying levels in the concentrate was examined in two experiments. The objective of the study was to evaluate the effect of rate of inclusion and presentation (dry vs. soaked) of wheat distiller’s grains, and the responses in behaviour and processes of intake. In both experiments, the rates of inclusion were 1.00:0, 0.75:0.25, 0.50:0.50, 0.25:0.75 and 0:1.00 for wheat distiller’s grains/concentrate, respectively. The various mixtures of concentrate were offered to 10 horses according to two 5×5 Latin squares for 10 min and the rate of eating and processes of ingestion were assessed. When offered at a rate of 0.75 in the dry matter and not soaked, there was a significant reduction ( P<0.01) in the rate of ingestion of DM and chews per kg DM ( P<0.01). However, the rate of ingestion of soaked mixed concentrate declined rapidly ( P<0.01) when the rate of inclusion was greater than 0.5 of the dry matter. The behavioural responses of the animals were commensurate to the observations of rate of eating in the case of non soaked concentrate. When 0.75 of the concentrate DM was replaced with wheat distiller’s grains, a significant increase ( P<0.05) in the incidence of shorter than expected feeding bouts was observed. However if feeding was terminated, reversion of feeding occurred with a mean frequency of 0.767. The rate of cessation of feeding was also increased significantly when 0.75 or all of the concentrate DM was replaced with the distillery by-product. If the concentrate was soaked before offering, there was an increase ( P<0.05) in the number of feeding bouts when 0.25 of the concentrate was replaced with wheat distiller’s grains. However the processes of ingestion were not affected until 0.5 of the concentrate DM was replaced. Cessation of feeding was affected significantly by the previous behaviour ( P<0.001) especially when the animal interacts with the environment and resumption of feeding was reduced significantly ( P<0.01) as the rate of inclusion of wheat distiller’s grains increased. Wheat distiller’s grains can be used as a substitute to other energy and protein feeding-stuffs in the ration of the horse. However the inclusion rate depends on the method of presentation of the feed to the animal. Soaking of the concentrate prior to feeding allowed a reduced level of distillery by-product to be incorporated into the ration. Least cost formulation of concentrates for horses should therefore consider the nutritive composition of the feeding stuff, the potential of the novel feeding-stuff to disrupt behaviour during feeding and the cost of the formulation.

Relationship between feeding time and food intake in hamadryas baboons (Papio hamadryas) and the value of feeding time as predictor of food intake

The relationship among time spent feeding, number of feeding bouts, feeding bout length, and the amount of food ingested was determined in a study of 18 hamadryas baboons (Papio hamadryas) at the German Primate Center (DPZ). There was considerable within- and between-subject variation in all four variables. Feeding time and number of feeding bouts could explain only 30% and 40%, respectively, of the variation in the ingested amount of food. No relationship was found between feeding bout length and amount of food ingested. The reason for these weak relationships is the high within- and between-subject variation in ingestion rate. If the amount of ingested food is estimated by multiplying mean ingestion rates of various subject categories by feeding time, deviations from true amounts range from 8% to 50%. A prediction of feeding success solely by measuring feeding time or number of feeding bouts is therefore not recommended and an estimation of food intake from ingestion rates and feeding time has to be treated with caution. Zoo Biol 18:495–505, 1999. © 1999 Wiley-Liss, Inc.