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 379 records · Page 21Linked to original sources
PubMed1986

Role of particle size and forage quality in digestion and passage by cattle and sheep.

Diminution of forage particles includes mastication, chewing, and digestion. In rumen of cattle and sheep fed all forage diets, particle size can range from 200 to over 1200 microns. Particle size reduction to about less than 1200 microns must occur before passage. Dietary particle size may influence rumen particle size, but mastication and rumination minimizes differences among diets. Ruminants expend considerable effort to move digesta. Density, cell wall percentage, osmotic pressure, and pH may affect propulsion. Dense particles may sink to the bottom and resist escape. Cell wall may reduce digestion and passage. Osmotic pressure or pH may affect digestive efficiency and rhythm of intestinal tract muscles. Chewing, exercise, physiological functions, and body size may also affect the reduction of forage particle size. More effort is necessary to chew high than low fiber diets. Young cattle (less than 225 kg) lack rumination capability and body size to process forage particles efficiently. Exercised sheep (26,400 kg-m/d) ate less forage and ruminated less than controls. Other body functions, such as lactation, appear to influence chewing patterns and rumination. These relationships are poorly understood at best and need additional intensive examination.

Animal Feed↗
PubMed1986

Performance of dairy cows fed forage and grain separately versus a total mixed ration.

Forty multiparous cows beyond peak production were fed forage ad libitum behind Calan doors and grain at 1 kg/2.5 kg milk through a computer controlled feeder, and 40 similar cows were fed a total mixed ration balanced for 32 kg milk behind Calan doors ad libitum. Based on mean milk production from d 16 through 21 of a preliminary period, cows were balanced into two groups within each group of 40 cows. Both groups received the originally assigned ration during d 22 through 49. During d 50 through 77, 20 cows were switched abruptly to the other ration and 20 remained on the original. Cows fed forage and grain separately had milk yields similar to those fed total mixed ration. Dry matter intake was lower for cows fed forage and grain separately from d 22 through 49 due to reduced forage intake and was also lower from d 50 through 77 due to decreased grain intake. Four percent fat-corrected milk production efficiency was higher for cows fed forage and grain separately. Abruptly changing cows from one feeding system to another did not influence milk yield, milk composition, or body weight gain. The computer controlled feeder system is an effective method to allot grain according to milk production requirements in freestall housing.

Analysis of Variance↗
PubMed1990

Forage intake, ruminal dry matter disappearance, and ruminal blood volatile fatty acids for steers in 18 and 32 degrees C temperatures.

Six steers with rumen cannulas and exteriorized carotid arteries were fed chopped alfalfa, orchardgrass, or tall fescue hay in ambient temperatures (18 and 32 degrees C) using a factorial arrangement of forage and temperature with repeated measurements. Arterial blood, venous blood, and rumen fluid were sampled for VFA at 0, 2, 4, and 7 h after forage was offered. Rate of digestion of plant cell wall was determined by in vitro methods. Rate of ingesta and particulate passage was determined by 144Ce marker. Volatile fatty acid concentrations in blood plasma and rumen fluid were not related to forage voluntary intake. Voluntary forage intake was related to calculated ruminal disappearance of cell wall (r2 of .94). Elevated ambient temperature, 32 degrees C, depressed voluntary forage intake but did not increase ruminal or blood VFA concentrations.

Animal Feed↗
PubMed1991

Effect of dietary forage:grain ratio on blood constituents in dairy cows.

Forty-nine primiparous and 44 multiparous lactating Holstein cows were used to study the effect of five dietary forage: grain ratios on blood constituents. Blood samples were collected in wk 2, 3, 4, 6, 8, 12, and 16 of lactation and were analyzed for glucose, urea, beta-hydroxybutyrate, and FFA. Increasing the percentage of forage in the diet decreased blood glucose concentration. Glucose levels were low at the beginning of lactation and increased as DMI increased. Increasing percentage of forage in the diet did not affect blood urea concentration. Increasing forage in the diet from 38.2 to 98.2% increased beta-hydroxybutyrate concentrations threefold during the first 4 wk of lactation in both primiparous and multiparous cows. The concentration of plasma FFA was higher in all the treatments at the beginning of lactation and decreased as lactation advanced. Dietary forage:grain ratio did not affect plasma FFA.

3-Hydroxybutyric Acid↗
PubMed1991

Milk production response to dietary forage:grain ratio.

Forty-four multiparous and 49 primiparous Holstein cows were assigned randomly at parturition to one of five diets differing in forage:grain ratio and studied for the entire lactation for effects of diet on milk production and milk composition, body condition, BW gain, health, and reproductive performance. Total mixed rations fed once daily consisted of alfalfa silage, high moisture ear corn, soybean meal, vitamins, and minerals. Percentages of forage in the diet (dry basis) for treatments 1 to 5 were postpartum wk 1 to 12 (38.2, 48.2, 58.2, 68.2, and 98.2); wk 13 to 26 (48.2, 58.2, 68.2, 88.2, and 98.2); and wk 27 to 44 (68.2, 78.2, 88.2, 98.2, and 98.2). Milk production (3.5% FCM in 305 d) was 8295, 8659, 7563, 6849, and 6000 kg for multiparous cows in treatments 1 to 5, respectively, and 7334, 7177, 6976, 6014, and 4750 kg for primiparous cows. Primiparous cows had decreased milk protein, BW gain, DMI and gross feed efficiency as forage increased in the diet. Multiparous cows in treatment 1 had depressed milk fat and lower DMI and gross feed efficiency compared with other treatments. Body condition scores tended to be lower as forage increased in the diet with both age groups. Increased forage in the diet did not cause any adverse effects on health and reproductive performance in either age group.

Animal Feed↗
PubMed1992

Influence of hay making on in situ nitrogen degradability of forages in cows.

The influence of hay making on in situ N degradability of forages was assessed by comparing the degradability of nine hays with that of standing forages at the time of harvest. Three ryegrass, two cocksfoot, and three alfalfa forages were used. The N degradability of hays was related closely to that of the corresponding standing forages (R = .91) and was, on average, lower (-2.5 points). This decrease in degradability after hay making was not constant; it increased when the degradability of the standing forage was high and when harvesting conditions were poor.

Animal Feed↗
PubMed1995

Prediction of protein degradation of forages from solubility fractions.

Two experiments were conducted to determine the relationship between enzymatic digestion of forage protein and fractionation based on solubility. The first experiment used 42 forages, each replicated three times, including different species, stages of maturity, and methods of conservation. Crude protein was fractionated into six parts for each forage by sequential extraction in TCA, bicarbonate-phosphate buffer, acetone, detergent at pH 7, and detergent with acid. Multiple regression analysis, with all the solubility fractions as independent variables, resulted in prediction of CP degradation by ruminal enzyme extract at 2 and 24 h; R2 were .88 and .81, respectively. Greater solubility in the buffer and the detergent at pH 7 was associated with higher protein degradation; solubility in acetone, detergent with acid, and insolubility were associated with lower degradation. In the second experiment, eight forages each replicated twice were digested with ruminal enzyme for 0, 2, 6, and 24 h and then were extracted as described. Solubility in TCA and acetone increased during degradation, but solubility in buffer, detergent with acid, and insolubility decreased. For both experiments, buffer-soluble CP was the only uniform fraction across forages; other fractions contained proteins that degraded at diverse rates. Solubility of CP is related to degradation properties, but further research is needed to improve the accuracy of predictions based on solubility.

Animal Feed↗
PubMed1995

Effect of forage to concentrate ratio on disappearance of vitamins A and E during in vitro ruminal fermentation.

The effects of forage to concentrate ratio and the commercial form of vitamins A and E on in vitro ruminal disappearance of retinol and alpha-tocopherol were studied. Ruminally fistulated cows were fed diets with either 80 or 50% forage. In vitro substrates that were similar to those fed to the donor cows were incubated with buffered ruminal fluid for 24 h. Different commercial forms of vitamin E (spray-dried, silicic acid adsorbate, and lipid-encased forms) and vitamin A (gelatin beadlet and lipid-encased forms) were added to the flasks. The vitamin E was all-rac-alpha-tocopheryl acetate, and the vitamin A was all-trans-retinyl acetate. The amount of alpha-tocopherol in the flasks was not affected by diet or form of vitamin E and did not change over the 24-h incubation. Retinol disappearance was not affected by form of vitamin A but was substantially higher for the 50% forage diet than for the 80% forage diet (72 vs. 20% at 24 h). These data suggest that ruminal metabolism of vitamin E is minimal and not affected by forage to concentrate ratio. Additionally, vitamin A destruction in the rumen was much higher when cows were fed a typical lactation diet than when fed a typical dry cow diet.

Animal Feed↗
PubMed1997

Substitution of neutral detergent fiber from forage with neutral detergent fiber from by-products in the diets of lactating cows.

Four lactating dairy cows that were ruminally and duodenally cannulated were used in an experiment with a 4 x 4 Latin square design to determine the effects of the substitution of neutral detergent fiber (NDF) from forage with NDF from wheat middlings, corn gluten feed, or a blend of distillers dried grains and hominy. Dietary crude protein and NDF averaged 18 and 31%, respectively, for the diet with 71.2% of the NDF from forage (control diet) and for diets with 55% of the NDF from forage (by-product diets). The substitution of NDF from these by-products for forage NDF did not affect dry matter intake (20.1 kg/d) or digestibility of organic matter. Total tract digestibility of acid detergent fiber was lower for cows fed the diet containing a blend of distillers dried grains and hominy than for cows fed the diet containing corn gluten feed. Microbial crude protein synthesis, milk production (23.9 kg/d), and milk fat percentage were similar for all cows, regardless of diet. Cows fed the diets containing wheat middlings or a blend of distillers dried grains and hominy had reduced ruminal pH compared with that of cows fed the diet containing corn gluten feed or the control diet. Diets containing 55% of total NDF from forage with 31% of total NDF from corn gluten feed, wheat middlings, or a blend of distillers dried grains and hominy can supply sufficient effective fiber to maintain normal ruminal function.

Ammonia↗
PubMed1998

Effects of replacing forage fiber or nonfiber carbohydrates with dried brewers grains.

Four primiparous Holstein cows in late lactation were used in a 4 x 5 Youden square design. Each cow was fitted with ruminal, duodenal, and ileal cannulas. Treatments were a control diet with a high concentration of forage, a control diet with a low concentration of forage, and three diets in which dried brewers grains replaced a portion of the forage, concentrate, or both. Cows were fed and milked twice daily in 14-d periods. Chromic oxide and Yb (soaked in acid) were used as markers for digesta flow and rate of passage, respectively. No significant differences in ruminal pH or rates of passage caused by treatment were detected. Although brewers grains had slower digestion rates of neutral detergent fiber (NDF) in situ and faster passage rates than did alfalfa, brewers grains had minor effects on site of NDF digestion. Intake of dry matter was depressed by the higher NDF concentrations in diets in which brewers grains replaced concentrate, but a long-term feeding study is needed to verify this conclusion. Although brewers grains did not appear to be very effective at stimulating milk fat percentage, dry matter intake was maintained when brewers grains replaced forage, and it appears that brewers grains can successfully replace a portion of the forage NDF in the diets of lactating cows.

Animal Feed↗
PubMed2000

Costs of plasticity in foraging characteristics of the clonal plant Ranunculus reptans.

In clonal plants, evolution of plastic foraging by increased lengths of leaves and internodes under unfavourable conditions may be constrained by costs and limits of plasticity. We studied costs and limits of plasticity in foraging characteristics in 102 genotypes of the stoloniferous herb Ranunculus reptans. We grew three replicates of each genotype with and three without competition by the naturally co-occuring grass Agrostis stolonifera. We used regression and correlation analyses to investigate potential costs of plasticity in lengths of leaves and stolon internodes, developmental instability costs of these traits, and a developmental range limit of these traits. We used randomization procedures to control for spurious correlations between parameters calculated from the same data. Under competition the number of rosettes, rooted rosettes, and flowers was 58%, 40%, and 61% lower, respectively, than in the absence of competition. Under competition lengths of leaves and stolon internodes were 14% and 6% smaller, respectively, than in the absence of competition. We detected significant costs of plasticity in stolon internode length in the presence of competition when fitness was measured in terms of the number of rosettes and the number of flowers (selection gradients against plasticity were 0.250 and 0.214, respectively). Within-environment variation (SD) in both foraging traits was not positively correlated with the corresponding plasticity, which indicates that there were no developmental instability costs. More plastic genotypes did not have less extreme trait values than less plastic genotypes for both foraging traits, which indicates that there was no developmental range limit. We conclude that in R. reptans costs of plasticity more strongly constrain evolution of foraging in the horizontal plane (i.e., stolon internode length) than in the vertical plane (i.e., leaf length).

Adaptation, Physiological↗
PubMedDate not supplied

The effects of food presentation and microhabitat upon resource monopoly in a ground-foraging ant (Hymenoptera: Formicidae) community.

In Neotropical wet forests several species of omnivorous, resource-defending ants, live and forage in close proximity to one another. Although the forest floor is heterogeneous in microhabitat and food quantity, little is known about the impact of microhabitat and food variation upon resource monopoly among ants. We investigated how food type and microhabitat influence food monopoly in resource-defending ants in old-growth tropical wet forest in the Caribbean lowlands of Costa Rica. We measured several microhabitat characteristics at 66 points in a 0.5 hectare plot, and baited each point with two categories of tuna bait. These baits were presented in "split" and "clumped" arrangements. We measured the frequency of bait monopoly by a single species, as well as the number of recruited ant foragers at a bait. Out of five common species, two (Wasmannia auropunctata and Pheidole simonsi) more frequently monopolized one bait type over the other, and one (P. simonsi) recruited more ants to the split baits. We then considered the recruitment response by all ant species in the community. We found that the frequency of monopoly, sharing, and the absence of ants at a given point in the rainforest differed with bait type. The frequency of monopoly was associated with microhabitat type in two out of eight microhabitat variables (leaf litter depth and palms); variation in two other types (canopy tree distance and leafcutter ant trails) was associated with changes in forager number. In at least two ant species, food presentation affected monopoly at baits; among all resource-defending ants, the microhabitats where ants foraged for food and the type of food located determined in part the frequency of monopoly and the number of foragers at the food item. These results suggest that the location and presentation of food items determines in part which ant species will utilize the resource.

Animals↗
PubMed2000

Artificial turf foraging boards as environmental enrichment for pair-housed female squirrel monkeys.

We investigated the use of artificial turf foraging boards to determine if providing captive squirrel monkeys an opportunity for semi-natural foraging behavior would 1) alter the monkeys' time budget to better approximate that seen in wild populations, 2) reduce the stereotypic, self-injurious, and aggressive behavior occasionally seen in captive squirrel monkeys, and 3) provide sustained enrichment. Five groups of pair-housed female squirrel monkeys were videotaped the week prior to, the week following, and for 2 weeks during the enrichment phase, when treat-enhanced boards were provided for 2 h daily. During the first 30 min of daily enrichment, inactivity declined 35.3%, locomotion increased 3.8%, and board-related behaviors occupied 36.3% of the activity budget; these changes were not evident after 1.5 h. Stereotypic behavior (pacing, headswinging, tailchewing) and aggression were not altered by the foraging opportunity. The foraging board retained the interest of the subjects across 2 weeks in the same daily pattern. Use of the foraging board altered the squirrel monkeys' time budget to become more like activity patterns seen in wild populations.

Animal Husbandry↗
PubMed2004

Diet, foraging, and use of space in wild golden-headed lion tamarins.

Lion tamarins (Callitrichidae: Leontopithecus) are small frugi-faunivores that defend large home ranges. We describe results from the first long-term investigation of wild golden-headed lion tamarins (L. chrysomelas; GHLTs). We present data about activity budgets, daily activity cycles, diet, daily path length, home range size, home range overlap, and territorial encounters for three groups of GHLTs that were studied for 1.5-2.5 years in Una Biological Reserve, Bahia State, Brazil, an area characterized by aseasonal rainfall. We compare our results to those from other studies of lion tamarins to identify factors that may influence foraging and ranging patterns in this genus. Ripe fruit, nectar, insects, and small vertebrates were the primary components of the GHLT diet, and gums were rarely eaten. Fruit comprised the majority of plant feeding bouts, and the GHLTs ate at least 79 different species of plants from 32 families. The most common foraging sites for animal prey were epiphytic bromeliads. The GHLTs defended large home ranges averaging 123 ha, but showed strong affinities for core areas, spending 50% of their time in approximately 11% of their home range. Encounters with neighboring groups averaged two encounters every 9 days, and they were always aggressive. Data about time budgets and daily activity cycles reveal that the GHLTs spent most of their time foraging for resources or traveling between foraging sites distributed throughout their home ranges. The GHLTs spent much less time consuming exudates compared to lion tamarins in more seasonal environments. Additionally, the GHLTs had much larger home ranges than golden lion tamarins (L. rosalia), and did not engage in territorial encounters as frequently as L. rosalia. GHLT ranging patterns appear to be strongly influenced by resource acquisition and, to a lesser extent, by resource defense.

Age Factors↗
PubMed2007

Age and seasonal effects on predator-sensitive foraging in squirrel monkeys (Saimiri sciureus): a field experiment.

A field experiment was conducted to examine the effect of perceived predation risk on the use of foraging areas by juvenile and adult primates under different conditions of local food abundance. Wild squirrel monkeys, Saimiri sciureus, were observed in an experiment conducted during the dry and the wet seasons at a site in Eastern Amazonia, Brazil. Animals were presented with feeding platforms that differed in food quantity and exposure to aerial predators through varying vegetative cover. In the dry season, juveniles and adults chose platforms based solely on food quantity. However, in the wet season, juveniles foraged preferentially on high-reward platforms only if cover level also was high (i.e., potentially offered greater concealment from predators). In contrast, adults showed the same pattern of platform use regardless of season. These results indicate that age and local resource availability based on seasonality affect whether primates forage in a predator-sensitive manner. Juveniles may be more sensitive to predation risk when foraging, and individuals may take fewer risks when resource abundance is high in their environment.

Age Factors↗
PubMed2002

Cross-site differences in foraging behavior of white-faced capuchins (Cebus capucinus).

Researchers have identified a variety of cross-site differences in the foraging behavior of free-ranging great apes, most notably among chimpanzees (Pan troglodytes) and more recently orangutans (Pongo pygmaeus), that are not due to obvious genetic or ecological differences. These differences are often referred to as "traditions." What is not known is whether this high level of interpopulation variation in behavior is limited to hominoids. In this study, we use long-term data from three Costa Rican field sites that are geographically close and similar ecologically to identify potential foraging traditions in white-faced capuchins (Cebus capucinus). Foraging traditions are predicted in Cebus because of many behavioral and morphological convergences between this genus and the great apes. The processing techniques used for the same food species were compared across sites, and all differences found were classified as present, habitual, or customary. Proximity data were also analyzed to determine if social learning mechanisms could explain variation in foraging behavior. Of the 61 foods compared, we found that 20 of them are processed differently by capuchins across sites. The differences involve pound, rub, tap, "fulcrum," "leaf-wrap," and "army ant following." For most of the differences with enough data to analyze, the average proximity score of the "matched" dyads (two individuals within a group who shared a "different" processing technique) was statistically higher than the average proximity score of the remaining "unmatched" dyads.

Animals↗
PubMed1997

Size-assortative shoaling in fish: the effect of oddity on foraging behaviour

Current theory predicts that fish should show size-assortative shoaling in order to avoid increased predation risk by being the odd one out (oddity effect), or in order to minimize competition for food. I investigated with three-spined sticklebacks, Gasterosteus aculeatusthe importance of the oddity effect in promoting size-assortative shoaling. The greater an individual assesses its predation risk the less actively it is likely to forage. Hence, I examined with small and large fish whether an individual's foraging activity depends on its appearance (size) in relation to that of others in a shoal. The shoals were composed of three, six and 12 fish. Either one individual deviated in size from the rest of the shoal members or all the fish in a shoal were of similar size. When a stickleback was larger than others in the shoal its foraging activity was lower than that of large individuals in a shoal dominated by large fish or those in a size-assorted shoal. Small sticklebacks, however, did not change their foraging activity on the basis of their appearance in a shoal. These responses of individuals to their appearance did not depend on shoal size nor on the presence or absence of a predator. The results suggest that the oddity effect is likely to prevent larger sticklebacks from joining shoals of smaller individuals. They also suggest that factors other than the oddity effect, potentially food competition, may be more important in leading individuals to avoid the company of larger ones and prefer shoaling with matching conspecifics.

Journal Article↗
PubMed1997

Patch departure decisions by spice finches foraging singly or in groups

The marginal value theorem predicts that when resources are clumped in space, a forager can maximize its rate of intake by deciding to leave a patch when its current feeding rate falls below the average for the habitat. A group version of the model predicts that when rate-maximizing group members share a patch, they should leave sooner, and each with less gain, than single animals exploiting the same patch. We tested these predictions in the laboratory by measuring patch departure decisions of spice finches, Lonchura punctulataexploiting food patches alone or in groups of three under two habitats that require different travel times. As predicted, group members left the patch sooner and with fewer seeds than single foragers. Unlike the model's assumptions, however, birds did not share the patch equally, and their exploitation curves could not be simply derived from those of single foragers. Grouping decreased the effect of travel time on patch exploitation. Moreover, within each group the bird expected to leave first delayed its departure although it collected fewer seeds than the others. This delayed departure could aim to maintain group membership. We noted an increased variability in seed number collected by group members compared with single foragers, which could be a cost of group foraging.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Journal Article↗