Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Foraging”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1982

Diurnal variations in bacterial numbers and fluid parameters in ruminal contents of animals fed low- or high-forage diets.

Differential carbohydrate media and anaerobic replica plating techniques were used to assess the degrees of diurnal variations in the direct and viable cell counts as well as the carbohydrate-specific subgroups within the mixed rumen bacterial populations in cattle fed maintenance (metabolizable energy) levels of either a high-forage or a high-concentrate diet once daily. The rumen was sampled at 1 h before feeding and 2, 4, 8, 12, and 16 h after feeding, and selected microbiological parameters of the isolated bacterial populations were assessed. Corresponding samples of ruminal fluid were assayed for fermentation acids, carbohydrate, ammonia, and pH changes. The data showed that regardless of diet, total bacterial numbers remained fairly constant throughout the day. The number of viable bacteria declined 40 to 60% after feeding and then increased to a maximum at 16 h postfeeding. Changes occurred in the carbohydrate-specific subgroups within the bacterial populations, and some of the changes were consistent with a predicted scheme of ruminal feedstuff carbohydrate fermentation. Regardless of diet, however, soluble-carbohydrate-utilizing bacteria predominated at all times. Xylan-xylose and pectin subgroups respectively comprised about one-half and one-third of the population when the high-forage diet was given. These subgroups, along with the cellulolytics, constituted lesser proportions of the population when the high-concentrate diet was given. The cellulolytic subgroup was the least numerous of all subgroups regardless of diet but followed a diurnal pattern similar to that predicted for cellulose fermentation. There were few diurnal variations or differences in bacterial cell compositions and ruminal fluid parameters between diets. The observed similarities and dissimilarities of the rumen bacterial populations obtained when the two diets were given are discussed. The data are consistent with the versatility and constancy of the rumen as a stable, mature microbial system under the specific low-level feeding regimens used.

Anaerobiosis↗
PubMed1984

Isolation and characterization of dinitrogen-fixing bacteria from the rhizosphere of temperate cereals and forage grasses.

N(2)(C(2)H(2))-fixing bacteria were isolated from the rhizosphere of various cereals and forage grasses grown in the greenhouse and from the rhizosphere of field-grown wheat in Sweden. All 46 isolates from the greenhouse plants lost their nitrogenase activity during purification. By imposing a stronger selection pressure, we obtained pure isolates with nitrogenase activity from field-grown wheat. Some isolates were identified as Enterobacter agglomerans and Bacillus polymyxa, but several bacteria of uncertain taxonomy also occurred. One of the isolates grew and reduced acetylene only in the presence of other bacteria or certain vitamins. Species of Azotobacter or Azospirillum could not be isolated from the rhizosphere of any of the cereals and forage grasses studied.

Journal Article↗
PubMed1998

Influence of lactobacillus spp. from An inoculant and of weissella and leuconostoc spp. from forage crops on silage fermentation

Lactobacillus spp. from an inoculant and Weissella and Leuconostoc spp. from forage crops were characterized, and their influence on silage fermentation was studied. Forty-two lactic acid-producing cocci were obtained from forage crops and grasses. All isolates were gram-positive, catalase-negative cocci that produced gas from glucose, and produced more than 90% of their lactate in the D-isomer form. These isolates were divided into groups A and B by sugar fermentation patterns. Two representative strains from the two groups, FG 5 and FG 13, were assigned to the species Weissella paramesenteroides and Leuconostoc pseudomesenteroides, respectively, on the basis of DNA-DNA relatedness. Strains FG 5, FG 13, and SL 1 (Lactobacillus casei), isolated from a commercial inoculant, were used as additives to alfalfa and Italian ryegrass silage preparations. Lactic acid bacterium counts were higher in all additive-treated silages than in the control silage at an early stage of ensiling. During silage fermentation, inoculation with SL 1 more effectively inhibited the growth of aerobic bacteria and clostridia than inoculation with strain FG 5 or FG 13. SL 1-treated silages stored well. However, the control and FG 5- and FG 13-treated silages had a significantly (P < 0.05) higher pH and butyric acid and ammonia nitrogen contents and significantly (P < 0. 05) lower lactate content than SL 1-treated silage. Compared with the control silage, SL 1 treatments reduced the proportion of D-(-)-lactic acid, gas production, and dry matter loss in two kinds of silage, but the FG 5 and FG 13 treatments gave similar values in alfalfa silages and higher values (P < 0.05) in Italian ryegrass silage. The results confirmed that heterofermentative strains of W. paramesenteroides FG 5 and L. pseudomesenteroides FG 13 did not improve silage quality and may cause some fermentation loss.

Journal Article↗
PubMed1999

Characterization and identification of Pediococcus species isolated from forage crops and their application for silage preparation.

Pediococcus species isolated from forage crops were characterized, and their application to silage preparation was studied. Most isolates were distributed on forage crops at low frequency. These isolates could be divided into three (A, B, and C) groups by their sugar fermentation patterns. Strains LA 3, LA 35, and LS 5 are representative isolates from groups A, B, and C, respectively. Strains LA 3 and LA 35 had intragroup DNA homology values above 93.6%, showing that they belong to the species Pediococcus acidilactici. Strain LS 5 belonged to Pediococcus pentosaceus on the basis of DNA-DNA relatedness. All three of these strains and strain SL 1 (Lactobacillus casei, isolated from a commercial inoculant) were used as additives to alfalfa and Italian ryegrass silage preparation at two temperatures (25 and 48 degrees C). When stored at 25 degrees C, all of the inoculated silages were well preserved and exhibited significantly (P < 0.05) reduced fermentation losses compared to that of their control in alfalfa and Italian ryegrass silages. When stored at 48 degrees C, silages inoculated with strains LA 3 and LA 35 were also well preserved, with a significantly (P < 0.05) lower pH, butyric acid and ammonia-nitrogen content, gas production, and dry matter loss and significantly (P < 0.05) higher lactate content than the control, but silages inoculated with LS 5 and SL 1 were of poor quality. P. acidilactici LA 3 and LA 35 are considered suitable as potential silage inoculants.

Colony Count, Microbial↗
PubMed1972

Fermentation of isolated pectin and pectin from intact forages by pure cultures of rumen bacteria.

Studies on the rate and extent of galacturonic acid and isolated pectin digestion were carried out with nine strains of rumen bacteria (Butyrivibrio fibrisolvens H10b and D16f, Bacteroides ruminicola 23 and D31d, Lachnospira multiparus D15d, Peptostreptococcus sp. D43e, B. succinogenes A3c, Ruminococcus flavefaciens B34b, and R. albus 7). Only three strains, 23, D16f, and D31d, utilized galacturonic acid as a sole energy source, whereas all strains except A3c and H10b degraded (solubilized) and utilized purified pectin. Nutrient composition of the basal medium and separate sterilization of the substrate affected the rate and extent of fermentation for both substrates. Pectin degradation and utilization were measured with two maturity stages each of intact bromegrass and alfalfa. For bromegrass I, all strains tested (B34b, 23, D16f, D31d, D15d, and D43e) degraded a considerable amount of pectin and, with the exception of B34b, utilized most of what was degraded. Similar, but lower, results were obtained with bromegrass II, except for the two strains of B. ruminicola, 23 and D31d, which were unable to degrade and utilize pectin from this forage. All strains were able to degrade and utilize pectin from both maturity stages of alfalfa; however, values were considerably lower for strains 23 and D31d. Synergism studies, in which a limited utilizing strain, B34b, was combined with the limited degrading strain, D31d, resulted in a slight increase in degradation and a very marked increase in utilization of the pectin in all four forages. Similar results were obtained on both alfalfa substrates with a combination of strains B34b and D16f; however, no increases were observed with this combination on bromegrass.

Anaerobiosis↗
PubMed1976

Ultrastructure of rigid and lignified forage tissue degradation by a filamentous rumen microorganism.

A small (less than 1 mum)-filamentous, branching microorganism was observed in Gram-stained smears of the rumen microflora and was found to degrade tissues in forage samples incubated in vitro and in vivo with rumen fluid and observed by scanning and transmission electron microscopy. The microbe had prokaryotic cytoplasmic features and a gram-positive type of cell wall structure. Round to oval bodies apparently attached to hyphae resembled the sporulation pattern reported for Micromonospora. Filaments and rod and coccal forms of the microbe degraded rigid forage cell walls and lignified, thick-walled sclerenchymal cells. Location of the microbe at a slight distance from the degraded zones suggested the action of extracellular enzymes. The presence of a microbe with the capability of degrading lignified tissue represents an important and unique function in the rumen ecosystem.

Bacteria↗
PubMed1996

Effect of forage supplements on the incidence of bloat in dairy cows grazing high clover pastures.

The effect of offering forage supplements of different compositions was examined in two experiments with cows grazing high clover swards. In the first experiment strawmix supplements of high or low energy content (11 and 9 MJ metabolisable energy/kg dry matter [DM]) and high or low crude protein content (17 and 4 g/kg DM) were offered for periods of three weeks. The energy and protein contents were varied by the content of molasses and soyabean meal, respectively. The high energy, high protein supplement increased the incidence of bloat, and the low energy, high protein supplement reduced it, compared with grazing alone. Bloat was most evident in the first two weeks of each feeding period, suggesting that the cows partially adapted to the diets within three weeks. In the second experiment silage supplements reduced the incidence of bloat among cows grazing both tall and short swards. The most suitable forages to feed when there is a risk of bloat are those that are slowly fermented in the rumen but are eaten in sufficient quantity to reduce periods of rapid herbage intake.

Animal Feed↗
PubMed2000

Effect of condensed tannins extracted from four forages on the viability of the larvae of deer lungworms and gastrointestinal nematodes.

The inhibitory activity of condensed tannins extracted from four forage legume plants were evaluated by using a larval migration inhibition assay. The first (L1) and third (L3) stages of deer lungworm (Dictyocaulus viviparus), and the third stage (L3) of deer gastrointestinal nematodes were incubated with tannins extracted from Lotus pedunculatus, Lotus corniculatus, sulla (Hedysarum coronarium) and sainfoin (Onobrychus viciifolia). The tannins extracted from all the forages had inhibitory activity as measured by their ability to paralyse the larvae and inhibit them from passing through sieves. At the highest concentration used (1200 microg/ml) the tannins extracted from sainfoin had the highest activity against ensheathed L1 lungworm larvae (58 per cent), followed by L. pedunculatus (45 per cent), sulla (42 per cent) and L. comiculatus (35 per cent) when the larvae were incubated at 37 degrees C. The same trend, but with lower activities, was observed when the larvae were incubated at 22 degrees C. Anthelmintic activity against L3 lungworm larvae was evaluated by measuring the death rate of ensheathed L3 larvae after incubation with condensed tannins for two, 24 and 48 hours at room temperature (22 degrees C). The death rate was significantly higher (P<0.001) after 48 hours incubation than after two hours or 24 hours, and significantly higher (P<0.001) after 24 hours than after two hours incubation. Condensed tannins from sainfoin had the highest inhibitory activity followed by L. pedunculatus, sulla and L. comiculatus. The tannins from sainfoin also had the highest activity against L3 larvae of gastrointestinal nematodes, followed by L. pedunculatus, sulla and L. comiculatus. Exsheathed larvae of gastrointestinal nematodes were significantly more susceptible to the action of the tannins than ensheathed larvae.

Animals↗
PubMed2006

Genetic diversity among varieties of the native forage grass Trichloris crinita based on AFLP markers, morphological characters, and quantitative agronomic traits.

We assessed the genetic diversity in Trichloris crinita (Poaceae) varieties from South America, using AFLPs, morphological characters, and quantitative agronomic traits. Owing to the importance of this species for range grazing, we first characterized the varieties based on forage productivity. Biomass production varied 9 fold among the materials evaluated. Analysis of AFLP fingerprints allowed the discrimination of all varieties with a few selected primer combinations. Pair-wise genetic similarities, using marker data, ranged from 0.31 to 0.92 (Jaccard coefficients). Marker-based unweighted pair group method with arithmetic averaging (UPGMA) cluster analysis did not show geographical clustering, but rather grouped the varieties according to their biomass production. We identified 18 markers associated with biomass production, of which 8 showed complete correlation (r = 1.00) with this trait. These DNA markers can be used to assist selection for high forage productivity in T. crinita. Cluster analysis using morphological and quantitative characters revealed 4 distinct groups of varieties, clearly separated according to their biomass yield. The variables foliage height and basal diameter were strongly correlated with biomass production and these phenotypic markers can be used to select productive plants. The relations among the varieties based on AFLP data were significantly correlated with those based on agronomic and morphological characters, suggesting that the 2 systems give similar estimates of genetic relations among the varieties.

Animal Feed↗
PubMed1993

Social factors influencing performance of a foraging task for captive chimpanzees.

The performance of captive chimpanzees (Pan troglodytes) during a simulated foraging activity was compared to that reported for the foraging behavior of wild chimpanzees. The ability to find hidden fruit in a large outdoor play area was measured for 34 subjects housed in ten separate groups. Sex differences were apparent, with females searching for and finding significantly more fruit than males did. Chimpanzees of high and medium dominance rank found more fruit than those of low rank. Neither age nor stage of the female sexual cycle exerted an influence. The subjects became more proficient at finding fruit during the second block of trials. The results reflect possible influences of captivity on chimpanzee social behavior.

Animals↗
PubMed1995

Foraging synchrony in a group of Yakushima macaques (Macaca fuscata yakui).

The synchrony of behaviour among individuals in a group of Yakushima macaques was evaluated in relation to group size and food resources. The degree of synchrony was greater when the group was small (5-8 individuals) than when it was large (15-19 individuals). Diet did not affect the degree of synchrony. However, the duration of the 'active phase', in which most members of the group synchronized feeding and moving, was shorter when they fed mostly on fruit and seeds (fruit- and seed-eating season) than when they fed mostly on leaves and fallen seeds (leaf- and fallen-seed-eating season). When the group was large, the monkeys ranged over a greater area and foraged in fewer trees during the fruit-and seed-eating season than during the leaf- and fallen-seed-eating season. However, this tendency was not so clear when the group was small. These results suggest that the extent to which the distribution of food resources determines patterns of foraging increases with group size and that monkeys in a larger group reduce levels of intragroup food competition in order to obtain sufficient food.

Animals↗
PubMed1993

Estrogenic activity in forages: diagnostic use of the classical mouse uterine bioassay.

The classical mouse uterine bioassay was evaluated and adapted for routine diagnostic use in response to requests for evaluation of forages suspected of being estrogenic. Forages were extracted in acetone or 10% ethanol in acetone (v/v). Extracts were mixed with ground corn-based mouse feed. Immature female mice (n = 3/group) were fed a total of 100 g of the ground feed for 5 days. Body weights were monitored before and after the trial. After 6 days, the mice were euthanized and uterine weights were determined. Mean uterine weights were compared using 1-way analysis of variance with preselected contrasts for individual means. Selected uteruses were fixed in 10% neutral buffered formalin for histologic examination. Control feeds, diethylstilbestrol (DES), estradiol, coumestrol, feeds with no reported estrogenic properties, and a feed that caused hyperestrogenism in cattle were tested. Moderate levels of estrogenic compounds resulted in dose-responsive uterine enlargements (10-270 ppm coumestrol over 5 days). Extremely high levels of estrogen frequently resulted in feed refusal and lack of uterine enlargement (10 ppm DES, 100 ppm estradiol). Diagnostically significant estrogenic activity was recovered from the feed known to have been estrogenic in cattle. The classical mouse uterine bioassay was relatively inexpensive, quick, repeatable, and capable of detecting clinically relevant coumestrol levels in hay.

Animal Feed↗
PubMed1995

Comparison of four methods for forage nitrate analysis.

Twenty forage samples were collected and selected for variation in nitrate content. Each forage samples was analyzed 4 times by 4 different methods: diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic. Five feed extracts were spiked with 2 different amounts of nitrate and analyzed by each method. The spectrophotometric and nitrate-selective electrode had similar percent recoveries, which were close to 100%. The nitrate-selective electrode method had the least variation of the 4 methods. The diphenylamine spot plate method had the poorest average recovery, greatest variation, and was the least accurate. The average coefficients of variation for all samples within a method were 15%, 12%, 6.4%, and 16 for the diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic methods, respectively. The variation in the nitrate-selective electrode method was lower (P < 0.05) than the other methods. The results from this study suggest that the nitrate-selective electrode method is more accurate and precise than the other methods of analysis tested.

Animal Feed↗
PubMed2005

Opisthobranchia (Mollusca, Gastropoda) - more than just slimy slugs. Shell reduction and its implications on defence and foraging.

BACKGROUND: In general shell-less slugs are considered to be slimy animals with a rather dull appearance and a pest to garden plants. But marine slugs usually are beautifully coloured animals belonging to the less-known Opisthobranchia. They are characterized by a large array of interesting biological phenomena, usually related to foraging and/or defence. In this paper our knowledge of shell reduction, correlated with the evolution of different defensive and foraging strategies is reviewed, and new results on histology of different glandular systems are included. RESULTS: Based on a phylogeny obtained by morphological and histological data, the parallel reduction of the shell within the different groups is outlined. Major food sources are given and glandular structures are described as possible defensive structures in the external epithelia, and as internal glands. CONCLUSION: According to phylogenetic analyses, the reduction of the shell correlates with the evolution of defensive strategies. Many different kinds of defence structures, like cleptocnides, mantle dermal formations (MDFs), and acid glands, are only present in shell-less slugs. In several cases, it is not clear whether the defensive devices were a prerequisite for the reduction of the shell, or reduction occurred before. Reduction of the shell and acquisition of different defensive structures had an implication on exploration of new food sources and therefore likely enhanced adaptive radiation of several groups.

Journal Article↗
PubMed2004

Learning, odour preference and flower foraging in moths.

Floral volatiles play a major role in plant-insect communication. We examined the influence of two volatiles, phenylacetaldehyde and alpha-pinene, on the innate and learnt foraging behaviour of the moth Helicoverpa armigera. In dual-choice wind tunnel tests, adult moths flew upwind towards both volatiles, with a preference for phenylacetaldehyde. When exposure to either of these volatiles was paired with a feeding stimulus (sucrose), all moths preferred the learnt odour in the preference test. This change in preference was not seen when moths were exposed to the odour without a feeding stimulus. The learnt preference for the odour was reduced when moths were left unfed for 24 h before the preference test. We tested whether moths could discriminate between flowers that differed in a single volatile component. Moths were trained to feed on flowers that were odour-enhanced using either phenylacetaldehyde or alpha-pinene. Choice tests were then carried out in an outdoor flight cage, using flowers enhanced with either volatile. Moths showed a significant preference for the flower type on which they were trained. Moths that were conditioned on flowers that were not odour-enhanced showed no preference for either of the odour-enhanced flower types. The results imply that moths may be discriminating among odour profiles of individual flowers from the same species. We discuss this behaviour within the context of nectar foraging in moths and odour signalling by flowering plants.

Acetaldehyde↗
PubMed2004

Testing olfactory foraging strategies in an Antarctic seabird assemblage.

Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense of smell, how they use odour cues to locate prey patches in the vast ocean is not well understood. Here, we investigate species-specific responses to 3-methyl pyrazine in a sub-Antarctic species assemblage near South Georgia Island (54 degrees 00 ' S, 36 degrees 00 ' W). Pyrazines are scented compounds found in macerated Antarctic krill (Euphausia superba), a primary prey item for many seabird species in this region. To examine behavioural attraction to this odour, we presented birds with either scented or 'unscented' vegetable oil slicks at sea. As a positive control for our experiments, we also compared birds' responses to a general olfactory attractant, herring oil. Responses to pyrazine were both highly species specific and consistent with results from earlier studies investigating responses to crude krill extracts. For example, Cape petrels (Daption capense), giant petrels (Macronectes sp.) and white-chinned petrels (Procellaria aequinoctialis) were sighted at least 1.8-4 times as often at pyrazine-scented slicks than at control slicks. Black-browed albatrosses (Diomedea melanophris) were only sighted at pyrazine-scented slicks and never at control slicks. Wilson's storm-petrels (Oceanites oceanicus), black-bellied storm-petrels (Fregetta tropica), great shearwaters (Puffinus gravis) and prions (Pachyptila sp.) were sighted with equal frequency at control and pyrazine-scented slicks. As expected, responses to herring oil were more common. With the exception of great shearwaters (Puffinus gravis), each of these species was sighted up to five times as often at slicks scented with herring oil compared with control slicks. Together, the results support the hypothesis that Antarctic procellariiforms use species-specific foraging strategies that are inter-dependent and more complex than simply tracking prey by scent.

Animals↗
PubMed2005

Metabolic adjustments to increasing foraging costs of starlings in a closed economy.

Knowledge of the physiological consequences of variation in food availability may be essential for understanding behavioural and life history responses to such variation. To study the physiological consequences of food availability animals are generally subjected to caloric restriction or starvation, thereby reducing the upper limit to the energy budget. The relevance of this approach to free-living animals is questionable, however, because under natural conditions low food availability often results in higher foraging costs, and everything else remaining equal this results in a higher energy budget. We manipulated food availability by varying the foraging costs and studied effects on daily energy expenditure (DEE) and energy allocation of captive starlings Sturnus vulgaris. Birds in a closed economy earned their food by flying between two perches 5 m apart. The probability of a reward was set at three different levels, thereby creating a 'poor', 'intermediate' and 'rich' environment. Compared with the rich environment, birds flew 4 times more (2.3 h per day) in the poor environment, and increased DEE by 43% to 220 kJ day-1 (3.7xBMR), within the range of free-living parents rearing young. To our knowledge this is the first study to show an increase in DEE with decreasing food availability. Body mass, basal metabolic rate (BMR) and pectoral muscle size were reduced in the poor environment. Nocturnal energy expenditure was further reduced by reaching BMR earlier in the night. Calculations show that the energy demands in the poor environment could not be met with the flight costs of 20.5 W that we measured previously in a rich environment. Flight costs derived indirectly from the energy budget were lower, at 17.5 W, probably due to lower body mass. By reducing body mass by 20%, and economising during sleep, the birds achieved savings of 37% in their DEE. Without these savings, a DEE substantially higher than measured in free-living parents rearing young would be required to remain in energy balance. Surprisingly little data exist to verify whether free-living animals use the same tactics to survive periods with low food availability.

Animals↗
PubMed2006

The effects of depth, temperature and food ingestion on the foraging energetics of a diving endotherm, the double-crested cormorant (Phalacrocorax auritus).

Avian divers are confronted with a number of physiological challenges when foraging in cold water, especially at depth. Besides the obvious constraint imposed by the necessity to return to the surface for gas exchange, cold water temperatures and a reduction in body insulation due to the increase in pressure with dive depth will elevate the energetic costs of foraging in these endotherm divers. The complex effect that depth has on the diving energetics of aquatic birds has largely been ignored. To date, no study has assessed the impact of depth on diving energetics over a significant depth range, naturally encountered by the diver. We used open-circuit respirometry to study the energetic requirements of a foot-propelled pursuit diver, the double-crested cormorant (Phalacrocorax auritus albociliatus), when diving in a shallow (1 m) and deep (10 m) dive tank and when resting in air and water. We also investigated the modifying effects of air or water temperature and feeding status on the costs associated with diving and resting. Of all factors investigated, dive depth exercised the strongest influence on diving metabolic rate. Diving to 10 m depth increased metabolic rate on average by 22% when compared with shallow diving. Declining temperatures in air and water significantly elevated metabolic rate of cormorants resting in air and water as well as during diving. Feeding before resting in water or diving increased metabolic rate by 5-8% for at least 2 h. Cormorants maintained an elevated stomach temperature (>42 degrees C) when resting in water and during diving, even at cold temperatures. The elevated dive costs during deep diving, when compared with shallow diving, are most likely a consequence of the increased thermoregulatory costs associated with a greater heat loss to the water at depth. Nevertheless, our study shows that dive costs in double-crested cormorants are similar to those of other foot-propelled avian divers.

Animals↗