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PubMed2005

Effects of disodium fumarate on in vitro rumen microbial growth, methane production and fermentation of diets differing in their forage:concentrate ratio.

The effects of disodium fumarate on microbial growth, CH4 production and fermentation of three diets differing in their forage content (800, 500 and 200 g/kg DM) by rumen micro-organisms in vitro were studied using batch cultures. Rumen contents were collected from four Merino sheep. Disodium fumarate was added to the incubation bottles to achieve final concentrations of 0, 4 and 8 mm-fumarate, and (15)N was used as a microbial marker. Gas production was measured at regular intervals from 0 to 120 h of incubation. Fumarate did not affect (P>0.05) any of the measured gas production parameters. In 17 h incubations, the final pH and the production of acetate and propionate were increased linearly (P<0.001) by the addition of fumarate. Fumarate tended to increase (P=0.076) the organic matter disappearance of the diets and to decrease (P=0.079) the amount of NH3-N in the cultures. Adding fumarate to batch cultures tended (P=0.099) to decrease CH4 production, the mean values of the decrease being 5.4 %, 2.9 % and 3.8 % for the high-, medium- and low-forage diet, respectively. Fumarate tended to increase (P=0.082) rumen microbial growth for the high-forage diet, but no differences (P>0.05) were observed for the other two diets. These results indicate that the effects of fumarate on rumen fermentation depend on the nature of the incubated substrate, the high-forage diet showing the greatest response.

Acetates↗
PubMed2002

Novel forages for growth and health in farmed deer.

AIMS: This paper reviews recent research on the use of new forages in deer farming that may be useful for increasing growth in weaner deer for venison production, increasing the trace element status of deer, and for developing systems less reliant on chemical inputs, notably of anthelmintics used to control internal parasites. GROWTH: Grazing on pure swards of red clover (Trifolium pratense) or chicory (Chicorium intybus) increased weaner growth during autumn by 26-47% and during spring by 10-14%, relative to red deer (Cervus elaphus) grazed on perennial ryegrass (Lolium perenne) /white clover (Trifolium repens) pasture (0.8/0.2). Pre-weaning growth during lactation was increased by approximately 20%. These increases were due to increased rate of degradation of feed particles in the rumen, leading to higher digestibility and higher voluntary feed intakes (VFI). Red clover and chicory produce a greater proportion of their total dry matter (DM) during late summer and autumn than perennial ryegrass/white clover pastures, and are therefore better aligned with the seasonal feed requirements of deer. Grazing on the legume, sulla (Hedysarum coronarium), in autumn and spring increased the growth of weaner deer by 33% and 10%, respectively, relative to pasture-fed animals. PARASITES: Plants containing substantial concentrations of secondary compounds such as condensed tannins (CT) show promise for reducing problems caused by internal parasites. CT present in some legumes and the presence of low concentrations of both CT and sesquiterpene lactones in chicory are reviewed. Feeding sulla containing 35g CT /kg DM reduced abomasal nematode establishment and tended to reduce lungworm (Dictyocaulis eckerti) larval counts in faeces. Relative to weaner deer grazing pasture, weaner deer grazing chicory during autumn required fewer anthelmintic treatments without depressing growth rates. CT extracted from a range of legumes, and CT and sesquiterpene lactones extracted from chicory reduced the in vitro motility of both lungworm and gastrointestinal nematode larvae. The beneficial effects of CT-containing forages on the ability of young deer to manage internal parasite infections could be due to: indirect effects of CT resulting in increased amino-acid absorption, better meeting demands of the immune system; direct inhibitory effects of CT on parasite larvae and; taller plant morphology, reducing the ingestion of infective larvae. The effects of CT depend upon both their structure and CT Condensed tannins DM Dry matter L1 First-stage larvae L3 Infective third-stage larvae LWG Liveweight gain ME Metabolisable energy OM Organic matter OMD Organic matter digestibility VFIVoluntary food intake concentration in the plant, which vary between growing conditions, plant varieties and species. TRACE ELEMENTS: Chicory contained higher concentrations of copper and cobalt than perennial ryegrass/white clover pasture grown on the same farm, and deer grazing chicory had higher liver concentrations of both copper and vitamin B12. These forages may contribute to maintaining adequate trace element status in deer. CONCLUSIONS: Grazing systems that include legumes and herbs such as sulla, red clover and chicory can be used to substantially increase the growth of weaner deer for venison production whilst maintaining deer health and reducing requirements for chemical inputs. For maximum plant persistence and animal responses, these plants should be grown and managed as special-purpose forages and not used in seed mixtures with perennial grasses.

Journal Article↗
PubMed2004

Linking optimal foraging behavior to bird community structure in an urban-desert landscape: field experiments with artificial food patches.

Urban bird communities exhibit high population densities and low species diversity, yet mechanisms behind these patterns remain largely untested. We present results from experimental studies of behavioral mechanisms underlying these patterns and provide a test of foraging theory applied to urban bird communities. We measured foraging decisions at artificial food patches to assess how urban habitats differ from wildlands in predation risk, missed-opportunity cost, competition, and metabolic cost. By manipulating seed trays, we compared leftover seed (giving-up density) in urban and desert habitats in Arizona. Deserts exhibited higher predation risk than urban habitats. Only desert birds quit patches earlier when increasing the missed-opportunity cost. House finches and house sparrows coexist by trading off travel cost against foraging efficiency. In exclusion experiments, urban doves were more efficient foragers than passerines. Providing water decreased digestive costs only in the desert. At the population level, reduced predation and higher resource abundance drive the increased densities in cities. At the community level, the decline in diversity may involve exclusion of native species by highly efficient urban specialists. Competitive interactions play significant roles in structuring urban bird communities. Our results indicate the importance and potential of mechanistic approaches for future urban bird community studies.

Animals↗
PubMed1995

Chaser (Csr), a new gene affecting larval foraging behavior in Drosophila melanogaster.

Chaser (Csr) was uncovered in a gamma mutagenesis screen to identify genes that modify the larval foraging behavior of sitters to rovers. Rover larvae have significantly longer path lengths than sitters while foraging on a yeast and water paste. This difference is influenced by one major gene, foraging (for), which has two naturally occurring alleles, forR (rover) and fors (sitter). In a mutagenesis screen for modifiers of for, we identified three lines with viable mutations on chromosome 3 that alter foraging behavior. Each of these mutations increased larval path lengths in fors/fors larvae in a dominant fashion, and were not separable by recombination. These mutations are therefore probably allelic and define a new gene that we have called Csr. Csr was genetically localized using the lethal-tagging technique. This technique resulted in seven lines with a significant decrease in larval path-length and recessive lethal mutations on chromosome 3. We refer to these as reverted Csr (Csrrv) lines. Deficiencies that uncovered cytologically visible chromosome rearrangements in three of the seven reverted lines were used in a complementation analysis. In this way we mapped the lethal mutations in the Csrrv lines to cytological region 95F7-96A1 on the right arm of chromosome 3.

Alleles↗
PubMedDate not supplied

Genetic dissection of honeybee (Apis mellifera L.) foraging behavior.

We demonstrate the effects of a new quantitative trait locus (QTL), designated pln3, that was mapped in a backcross population derived from strains of bees selected for the amount of pollen they store in combs. We independently confirmed pln3 by demonstrating its effects on individual foraging behavior, as we did previously for QTLs pln1 and pln2 (Hunt et al. 1995). QTL pln2 is very robust in its effects on foraging behavior. In this study, pln2 was again shown to affect individual foraging behavior of workers derived from a hybrid backcross of the selected strains. In addition, pln2 was shown to affect the amount of pollen stored in combs of colonies derived from a wide cross of European and Africanized honeybees. This is noteworthy because it demonstrates that we can map QTLs for behavior in interstrain crosses derived from selective breeding and study their effects in unselected, natural populations. The results we present also demonstrate the repeatability of finding QTLs with measurable effects, even after outcrossing selected strains, suggesting that there is a relatively small subset of QTLs with major effects segregating in the population from which we selected our founding breeding populations. The different QTLs, pln1, pln2, and pln3, appear to have different effects, revealing the complex genetic architecture of honeybee foraging behavior.

Animals↗
PubMed1997

Analysis of forage fiber and cell walls in ruminant nutrition.

Analysis of the fiber or cell wall present in forages is of major concern in ruminant nutrition because diets often contain large amounts of forage, and the fiber fraction affects both feed intake and animal performance. Traditional extractive, gravimetric methods such as crude fiber and neutral detergent fiber recover variable amounts of the plant cell wall, but they remain popular because of their ease of use and the large feed data bases available for these methods. More intensive chemical methods utilizing chromatography and spectrometric analysis provide greater detail on cell wall composition and structure, but they have been used little in ruminant nutrition. Lignin analysis has remained problematic because no definitive reference method exists. Recently attention has focused on the measurement of lignin composition and cell wall phenolic acids; however, these methods have yet to be widely adopted in ruminant nutrition. The detergent fiber methods have been semi-automated to increase sample handling capacity. Near-infrared spectroscopy is routinely used for prediction of fiber concentration in forages and has greatly increased the ease of obtaining fiber analysis of forage samples. Widespread adoption in ruminant nutrition of the more sophisticated methods of cell wall analysis is unlikely to occur until these methods can be demonstrated to improve diet formulation and prediction of animal performance.

Animal Feed↗
PubMed2003

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids.

Understanding the trophodynamics of marine ecosystems requires data on the temporal and spatial variation in predator diet but, particularly for wide-ranging species, these data are often unavailable. The southern elephant seal (Mirounga leonina) consumes large quantities of fish and squid prey in the Southern Ocean relative to other marine mammals; however, how diet varies relative to seasonal and spatial foraging behaviour is unknown. We used fatty acid (FA) signature analysis of 63 blubber cores from adult female M. leonina over three seasons (winter 1999, summer 2000 and winter 2001) to determine diet structure. We detected significant differences between seasons and between the main foraging regions (Antarctic continental shelf versus pelagic). We used the FA profiles from 53 fish, squid and krill species to construct a discriminant function that would classify each seal, from its blubber sample as having a fish- or squid-FA profile. We determined that a higher proportion of M. leonina had fish-dominated diets during the winter and when foraging around the Antarctic continental shelf, and the majority had more squid-dominated diets during the summer when foraging pelagically. Thus, we were able to measure the coarse-scale diet structure of a major marine predator using FA profiles, and estimate its associated seasonal and temporal variation.

Adipose Tissue↗
PubMed2003

Regulation of ants' foraging to resource productivity.

We investigate the behavioural rule used by ant societies to adjust their foraging response to the honeydew productivity of aphids. When a scout finds a single food source, the decision to lay a recruitment trail is an all-or-none response based on the opportunity for this scout to ingest a desired volume acting as a threshold. Here, we demonstrate, through experimental and theoretical approaches, the generic value of this recruitment rule that remains valid when ants have to forage on multiple small sugar feeders to reach their desired volume. Moreover, our experiments show that when ants decide to recruit nest-mates they lay trail marks of equal intensity, whatever the number of food sources visited. A model based on the 'desired volume' rule of recruitment as well as on experimentally validated parameter values was built to investigate how ant societies adjust their foraging response to the honeydew productivity profile of aphids. Simulations predict that, with such recruiting rules, the percentage of recruiting ants is directly related to the total production of honeydew. Moreover, an optimal number of foragers exists that maximizes the strength of recruitment, this number being linearly related to the total production of honeydew by the aphid colony. The 'desired volume' recruitment rule that should be generic for all ant species is enough to explain how ants optimize trail recruitment and select aphid colonies or other liquid food resources according to their productivity profile.

Animal Communication↗
PubMed2004

State-dependent foraging rules for social animals in selfish herds.

Many animals gain benefits from living in groups, such as a dilution in predation risk when they are closely aggregated (referred to as the 'selfish herd'). Game theory has been used to predict many properties of groups (such as the expected group size), but little is known about the proximate mechanisms by which animals achieve these predicted properties. We explore a possible proximate mechanism using a spatially explicit, individual-based model, where individuals can choose to rest or forage on the basis of a rule-of-thumb that is dependent upon both their energetic reserves and the presence and actions of neighbours. The resulting behaviour and energetic reserves of individuals, and the resulting group sizes, are shown to be affected both by the ability of the forager to detect conspecifics and areas of the environment suitable for foraging, and by the distribution of energy in the environment. The model also demonstrates that if animals are able to choose (based upon their energetic reserves) between selecting the best foraging sites available and moving towards their neighbours for safety, then this also has significant effects upon individuals and group sizes. The implications of the proposed rule-of-thumb are discussed.

Animals↗
PubMed2006

Bumble-bee foragers infected by a gut parasite have an impaired ability to utilize floral information.

Parasitic infection can influence a variety of behavioural mechanisms in animals, but little is known about the effects of infection on the cognitive processes underlying ecologically relevant behaviours. Here, we examined whether parasitic infection alters cognitive aspects of foraging in a social insect, the bumble-bee (Bombus impatiens). In controlled experiments, we assessed the ability of foraging bees to discriminate rewarding from non-rewarding flowers on the basis of colour and odour. We found that natural and experimental infection by a protozoan parasite (Crithidia bombi, which lives exclusively within the gut tract), impaired the ability of foragers to learn the colour of rewarding flowers. Parasitic infection can thus disrupt central nervous system pathways that mediate cognitive processes in bumble-bees and as a consequence, can reduce their ability to monitor floral resources and make economic foraging decisions. It is postulated that this infection-induced change to cognitive function in bumble-bees is the result of communication between immune and nervous systems. Parasitized animals, including invertebrates, can therefore show subtle behavioural changes that are nonetheless ecologically significant and reflect complex mechanisms.

Animals↗
PubMed2006

Insect odour perception: recognition of odour components by flower foraging moths.

Odours emitted by flowers are complex blends of volatile compounds. These odours are learnt by flower-visiting insect species, improving their recognition of rewarding flowers and thus foraging efficiency. We investigated the flexibility of floral odour learning by testing whether adult moths recognize single compounds common to flowers on which they forage. Dual choice preference tests on Helicoverpa armigera moths allowed free flying moths to forage on one of three flower species; Argyranthemum frutescens (federation daisy), Cajanus cajan (pigeonpea) or Nicotiana tabacum (tobacco). Results showed that, (i) a benzenoid (phenylacetaldehyde) and a monoterpene (linalool) were subsequently recognized after visits to flowers that emitted these volatile constituents, (ii) in a preference test, other monoterpenes in the flowers' odour did not affect the moths' ability to recognize the monoterpene linalool and (iii) relative preferences for two volatiles changed after foraging experience on a single flower species that emitted both volatiles. The importance of using free flying insects and real flowers to understand the mechanisms involved in floral odour learning in nature are discussed in the context of our findings.

Acetaldehyde↗
PubMed2006

Quantitative analysis of bottlenose dolphin movement patterns and their relationship with foraging.

1. Broad-scale telemetry studies have greatly improved our understanding of the ranging patterns and habitat-use of many large vertebrates. However, there often remains considerable uncertainty over the function of different areas or the factors influencing habitat selection. Further insights into these processes can be obtained through analyses of finer scale movement patterns. For example, search behaviour may be modified in response to prey distribution and abundance. 2. In this study, quantitative analysis techniques are applied to the movements of bottlenose dolphins, recorded from land using a theodolite, to increase our understanding of their foraging strategies. Movements were modelled as a correlated random walk (CRW) and a biased random walk (BRW) to identify movement types and using a first-passage time (FPT) approach, which quantifies the time allocated to different areas and identifies the location and spatial scale of intensive search effort. 3. Only a quarter of the tracks were classed as CRW movement. Turning angle and directionality appeared to be key factors in determining the type of movement adopted. A high degree of overlap in search effort between separate movement paths indicated that there were small key sites (0.3 km radius) within the study area (4 km(2)). Foraging behaviour occurred mainly within these intensive search areas, indicating that they were feeding sites. 4. This approach provides a quantitative method of identifying important foraging areas and their spatial scale. Such techniques could be applied to movement paths for a variety of species derived from telemetry studies and increase our understanding of their foraging strategies.

Animals↗
PubMed2005

An interspecific comparison of foraging range and nest density of four bumblebee (Bombus) species.

Bumblebees are major pollinators of crops and wildflowers in northern temperate regions. Knowledge of their ecology is vital for the design of effective management and conservation strategies but key aspects remain poorly understood. Here we employed microsatellite markers to estimate and compare foraging range and nest density among four UK species: Bombus terrestris, Bombus pascuorum, Bombus lapidarius, and Bombus pratorum. Workers were sampled along a 1.5-km linear transect across arable farmland. Eight or nine polymorphic microsatellite markers were then used to identify putative sisters. In accordance with previous studies, minimum estimated maximum foraging range was greatest for B. terrestris (758 m) and least for B. pascuorum (449 m). The estimate for B. lapidarius was similar to B. pascuorum (450 m), while that of B. pratorum was intermediate (674 m). Since the area of forage available to bees increases as the square of foraging range, these differences correspond to a threefold variation in the area used by bumblebee nests of different species. Possible explanations for these differences are discussed. Estimates for nest density at the times of sampling were 29, 68, 117, and 26/km2 for B. terrestris, B. pascuorum, B. lapidarius and B. pratorum, respectively. These data suggest that even among the most common British bumblebee species, significant differences in fundamental aspects of their ecology exist, a finding that should be reflected in management and conservation strategies.

Animals↗
PubMed1970

Degradation and utilization of hemicellulose from intact forages by pure cultures of rumen bacteria.

Several pure strains of rumen bacteria have previously been shown to degrade isolated hemicelluloses from a form insoluble in 80% acidified ethanol to a soluble form, regardless of the eventual ability of the organism to utilize the end products as energy sources. This study was undertaken to determine whether similar hemicellulose degradation or utilization, or both, occurs from intact forages. Fermentations by pure cultures were run to completion by using three maturity stages of alfalfa and two maturity stages of bromegrass as individual substrates. Organisms capable of utilizing xylan or isolated hemicelluloses could degrade and utilize intact forage hemicellulose, with the exception of two strains of Bacteroides ruminicola which were unable to degrade or utilize hemicellulose from grass hays. Intact forage hemicelluloses were extensively degraded by three cellulolytic strains that were unable to use the end products; in general, these strains degraded a considerably greater amount of hemicelluloses than the hemicellulolytic organisms. Hemicellulose degradation or utilization, or both, varied markedly with the different species and strains of bacteria, as well as with the type and maturity stage of the forage. Definite synergism was observed when a degrading nonutilizer was combined with either one of two hemicellulolytic strains on the bromegrass substrates. One hemicellulolytic strain, which could not degrade or utilize any of the intact bromegrass hemicellulose alone, almost completely utilized the end products solubilized by the nonutilizer. Similar synergism, although of lesser magnitude, was observed when alfalfa was used as a substrate.

Animal Feed↗
PubMed2005

Use of tall fescue EST-SSR markers in phylogenetic analysis of cool-season forage grasses.

Microsatellites or simple sequence repeats (SSRs) are highly useful molecular markers for plant improvement. Expressed sequence tag (EST)-SSR markers have a higher rate of transferability across species than genomic SSR markers and are thus well suited for application in cross-species phylogenetic studies. Our objectives were to examine the amplification of tall fescue EST-SSR markers in 12 grass species representing 8 genera of 4 tribes from 2 subfamilies of Poaceae and the applicability of these markers for phylogenetic analysis of grass species. About 43% of the 145 EST-SSR primer pairs produced PCR bands in all 12 grass species and had high levels of polymorphism in all forage grasses studied. Thus, these markers will be useful in a variety of forage grass species, including the ones tested in this study. SSR marker data were useful in grouping genotypes within each species. Lolium temulentum, a potential model species for cool-season forage grasses, showed a close relation with the major Festuca-Lolium species in the study. Tall wheat grass was found to be closely related to hexaploid wheat, thereby confirming the known taxonomic relations between these species. While clustering of closely related species was found, the effectiveness of such data in evaluating distantly related species needs further investigations. The phylogenetic trees based on DNA sequences of selected SSR bands were in agreement with the phylogenetic relations based on length polymorphism of SSRs markers. Tall fescue EST-SSR markers depicted phylogenetic relations among a wide range of cool-season forage grass species and thus are an important resource for researchers working with such grass species.

Alleles↗
PubMed1993

Genetic analysis of the foraging microregion of Drosophila melanogaster.

The rover/sitter polymorphism in Drosophila melanogaster larval behaviour is a unique example of a genetically determined, naturally occurring behavioural polymorphism. Allelic variation at the foraging locus (for) accounts for the rover (long foraging paths) and sitter (short foraging paths) phenotypes. We previously developed lethal tagging and used deficiency mapping to place for in the 24A3-C5 interval on the polytene chromosome map, thereby defining the for microregion. Here, we subjected this microregion to mutational analysis to (i) isolate putative lethal foraging mutations and characterize their behavioural phenotypes to assess whether or not for is a vital locus, (ii) generate cytologically detectable chromosome rearrangements with breakpoints in or near for for more precise localization and for future molecular analysis of the for gene, and (iii) identify other gene loci in the immediate vicinity of the for locus. We recovered 10 gamma-induced and 33 ethyl methanesulfonate (EMS) induced new mutations that define seven complementation groups in 24A3-D4. Two new EMS-induced lethal for alleles and four gamma-induced rearrangements with breakpoints in for were identified, which allowed us to further localize for to 24A3-5. All lethal mutations in for resulted in an altered behavioural phenotype providing evidence that both vital and behavioural functions are encoded by for.

Alleles↗
PubMed1999

Relative medial and dorsal cortex volume in relation to foraging ecology in congeneric lizards.

The need to locate distributed resources such as mates, food, and nests is correlated with an enlarged hippocampus in many mammalian and avian species. This correlation is believed to be a consequence of selection for spatial ability. Little is known about how such ecological needs affect non-mammalian, non-avian species. In lizards, the putative hippocampal homologues are the dorsal cortex (DC) and medial cortex (MC). We examined the relationship between foraging ecology and the size of the DC and MC in congeneric male lizards. We predicted based on the mammalian and avian literature that Acanthodactylus boskianus, an active forager that captures clumped, immobile prey would have a larger MC and DC than A. scutellatus, a sit-and-wait predator, that captures mobile prey. Our previous behavioral studies showed that A. boskianus did not differ from A. scutellatus on a spatial task but that A. boskianus was significantly better at the reversal of a visual discrimination, another task that is hippocampally dependent in mammals. In the current study, we found that, relative to telencephalon volume, the MC and DC were larger in the active forager whereas a control region, the lateral, olfactory, cortex, was similar in size between species. The current anatomical results suggest that MC and DC size is related to active foraging in lizards and, along with our previous behavioral studies, show that it is possible for this relationship to occur in the absence of evidence for species differences in spatial memory.

Animals↗
PubMed1993

Transient compulsive foraging behavior associated with crack cocaine use.

Compulsive foraging behavior associated with use of crack cocaine involves compulsively searching the environment for possibly misplaced pieces of crack. Of 41 crack cocaine addicts evaluated, 33 (80.5%) reported at least some compulsive foraging associated with use of crack; 21 (51.2%) reported such behavior as always associated with crack use. The mean length of time spent in compulsive foraging was 90 minutes. Cocaine-induced foraging may represent a drug-induced model of a type of compulsive behavior.

Adult↗