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 271 records · Page 15Linked to original sources
PubMed2005

Role of NPY and its receptor subtypes in foraging, food hoarding, and food intake by Siberian hamsters.

Fasting has widespread physiological and behavioral effects such as increases in arcuate nucleus neuropeptide Y (NPY) gene expression in rodents, including Siberian hamsters. Fasting also stimulates foraging and food hoarding (appetitive ingestive behaviors) by Siberian hamsters but does relatively little to change food intake (consummatory ingestive behavior). Therefore, we tested the effects of third ventricular NPY Y1 ([Pro(34)]NPY) or Y5 ([D-Trp(34)]NPY) receptor agonists on these ingestive behaviors using a wheel running-based food delivery system coupled with simulated burrow housing. Siberian hamsters had 1) no running wheel access and free food, 2) running wheel access and free food, or 3) foraging requirements (10 or 50 revolutions/pellet). NPY (1.76 nmol) stimulated food intake only during the first 4 h postinjection ( approximately 200-1,000%) and mostly in hamsters with a foraging requirement. The Y1 receptor agonist markedly increased food hoarding (250-1,000%), increased foraging as well as wheel running per se, and had relatively little effect on food intake (<250%). Unlike NPY, the Y5 agonist significantly increased food intake, especially in foraging animals ( approximately 225-800%), marginally increased food hoarding (250-500%), and stimulated foraging and wheel running 4-24 h postinjection, with the distribution of earned pellets favoring eating versus hoarding across time. Across treatments, food hoarding predominated early postinjection, whereas food intake tended to do so later. Collectively, NPY stimulated both appetitive and consummatory ingestive behaviors in Siberian hamsters involving Y1/Y5 receptors, with food hoarding and foraging/wheel running (appetitive) more involved with Y1 receptors and food intake (consummatory) with Y5 receptors.

Animals↗
PubMed1998

Phototaxic foraging of the archaepaddler, a hypothetical deep-sea species.

An autonomous agent (animat, hypothetical animal), called the (archae) paddler, is simulated in sufficient detail to regard its simulated aquatic locomotion (paddling) as physically possible. The paddler is supposed to be a model of an animal that might exist, although it is perfectly possible to view it as a model of a robot that might be built. The agent is assumed to navigate in a simulated deep-sea environment, where it forages for autoluminescent prey. It uses a biologically inspired phototaxic foraging strategy, while paddling in a layer just above the bottom. The advantage of this living space is that the navigation problem--and hence our model--is essentially two-dimensional. Moreover, the deep-sea environment is physically simple (and hence easy to simulate): no significant currents, constant temperature, completely dark. A foraging performance metric is developed that circumvents the necessity to solve the traveling salesman problem. A parametric simulation study then quantifies the influence of habitat factors, such as the density of prey, and body geometry (e.g., placement, direction and directional selectivity of the eyes) on foraging success. Adequate performance proves to require a specific body geometry adapted to the habitat characteristics. In general, performance degrades gracefully for modest changes of the geometric and habitat parameters, indicating that we work in a stable region of "design space." The parameters have to strike a compromise between, on the one hand, to "see" as many targets at the same time as possible. One important conclusion is that simple reflex-based navigation can be surprisingly efficient. Additionally, performance in a global task (foraging) depends strongly on local parameters such as visual direction tuning, position of the eyes and paddles, and so forth. Behavior and habitat "mold" the body, and the body geometry strongly influences performance. The resulting platform enables further testing of foraging strategies or vision and locomotion theories stemming either from biology or from robotics.

Animals↗
PubMed2003

Escape from viscosity: the kinematics and hydrodynamics of copepod foraging and escape swimming.

Feeding and escape swimming in adult females of the calanoid copepod Temora longicornis Müller were investigated and compared. Swimming velocities were calculated using a 3-D filming setup. Foraging velocities ranged between 2 and 6 mm s(-1), while maximum velocities of up to 80 mm s(-1) were reached during escape responses. Foraging took place at Reynolds numbers between 2 and 6, indicating that viscous forces are considerable during this swimming mode. Inertial forces are much more important during escape responses, when Reynolds numbers of more than 100 are reached. High-speed film recordings at 500 frames s(-1) of the motion pattern of the feeding appendages and the escape movement of the swimming legs revealed that the two swimming modes are essentially very different. While foraging, the first three mouth appendages (antennae, mandibular palps and maxillules) create a backwards motion of water with a metachronal beating pattern. During escape movements the mouth appendages stop moving and the swimming legs beat in a very fast metachronal rhythm, accelerating a jet of water backwards. The large antennules are folded backwards, resulting in a streamlined body shape. Particle image velocimetry analysis of the flow around foraging and escaping copepods revealed that during foraging an asymmetrical vortex system is created on the ventral side of the animal. The feeding motion is steady over a long period of time. The rate of energy dissipation due to viscous friction relates directly to the energetic cost of the feeding current. During escape responses a vortex ring appears behind the animal, which dissipates over time. Several seconds after cessation of swimming leg movements, energy dissipation can still be measured. During escape responses the rate of energy dissipation due to viscous friction increases by up to two orders of magnitude compared to the rate when foraging.

Animals↗
PubMed2003

cGMP-dependent changes in phototaxis: a possible role for the foraging gene in honey bee division of labor.

Division of labor in honey bee colonies is influenced by the foraging gene (Amfor), which encodes a cGMP-dependent protein kinase (PKG). Amfor upregulation in the bee brain is associated with the age-related transition from working in the hive to foraging for food outside, and cGMP treatment (which increases PKG activity) causes precocious foraging. We present two lines of evidence in support of the hypothesis that Amfor affects division of labor by modulating phototaxis. We first show that a subset of worker bees involved in the removal of corpses from the hive had forager-like brain levels of Amfor brain expression despite being middle aged; age-matched food-handlers, who do not leave the hive to perform their job, had low levels of Amfor expression. This finding suggests that occupations that involve working outside the hive are associated with high levels of Amfor in brain. Secondly, foragers were much more positively phototactic than hive bees in a laboratory assay, and cGMP treatment caused a precocious onset of positive phototaxis. The cGMP effect was not due to a general increase in behavioral activity; cGMP treatment had no effect on locomotor activity under either constant darkness or a light:dark regime. The cGMP effect also was not due to changes in circadian rhythmicity; cGMP treatment had no effect on age at onset of locomotor circadian rhythmicity or the period of rhythmicity. The effects of Amfor on phototaxis are not related to peripheral processing; electroretinogram analysis revealed no effect of cGMP treatment on photoreceptor activity and no differences between untreated hive bees and foragers. The cAMP/PKA pathway does not appear to be playing a similar role to cGMP/PKG in the honey bee; cAMP treatment did not affect phototaxis and gene expression analysis revealed task-related differences only for the gene encoding the regulatory subunit, but not the catalytic subunit, of PKA. Our findings implicate one neural process associated with honey bee division of labor that can be affected by naturally occurring changes in the expression of AMFOR:

Aging↗
PubMed2006

Foraging energetics of a nectar-feeding ant: metabolic expenditure as a function of food-source profitability.

We examined the quantitative relationship between the energetic costs and benefits of nectar collection by nectar-feeding ants, Camponotus rufipes. In the laboratory, individual workers were trained to visit an artificial feeder that provided a sucrose solution of 1%, 5%, 10%, 30% or 50% at controlled flows, in a similar span range to those observed in natural nectar sources. We measured foraging times, nectar loads collected, and CO(2) production during actual feeding, as an indication of the energy expenditure for a single forager. Results show an increase in individual metabolic rates with increasing flow rate of sugar solution, but no dependence on sucrose concentration. This increase in metabolic expenditure does not depend on the crop load attained while feeding, as intuitively expected, and is therefore a result of an increased activity brought about by the food-source profitability experienced by the forager. The energy gained during collection of sugar solution is always higher than the energy spent by the ant. Even with a food source of lower quality than a natural source, the ants gain ca. tenfold of what they spend. Based on a simplified model, we calculated that foragers of C. rufipes could travel from 0.5 to 9 km with the energy gained in a single foraging trip only. These results suggest that decreasing foraging time is more important than increasing individual energetic efficiency when workers of the nectar-feeding ant C. rufipes decide to stop drinking and return to the nest with partial crop loads.

Animals↗
PubMed2001

Changes in the thoracic temperature of honeybees while receiving nectar from foragers collecting at different reward rates.

Mouth-to-mouth food exchange in eusocial insects (trophallaxis) contributes to the organization of complex social activities. In the case of honeybees, foragers returning from a nectar source transfer the food collected to receiver colony-mates through oral contact. Previous studies have shown that the speed of nectar transfer within each contact (unloading rate) increases when foragers return from feeding sites with higher profitability, i.e. with more concentrated sugar solutions or higher solution flow rates. However, there is no evidence that the nectar unloading rate is actually evaluated by hive-mates during food exchange. To investigate this, trophallaxis between donor bees returning from a feeder with different flow rates of sucrose solution (range 1.0-8.2 microl min(-1) of 50% w/w sucrose solution) and receiver hive-mates was studied by combining behavioural and infrared thermal analysis. The results show that when foraging bees returned from a feeder delivering a higher flow rate they initiated unloading at higher thoracic temperatures and transferred the solution at higher speed. During these food exchanges, the thoraces of receiver bees warmed up faster in proportion to increasing forager temperature and unloading rate. Therefore, whatever the variable actually evaluated by receivers (mostly nectar processors, i.e. bees that handle nectar in the hive) during trophallaxis (unloading rate and/or donor thoracic temperature), they raised their activity level in proportion to that of the foragers. In this way, receiver bees will intensify their nectar processing when nectar foragers return from more profitable sites.

Animals↗
PubMed2002

Group foraging sensitivity to predictable and unpredictable changes in food distribution: past experience or present circumstances?

The ideal free distribution theory (Fretwell & Lucas, 1970) predicts that the ratio of foragers at two patches will equal the ratio of food resources obtained at the two patches. The theory assumes that foragers have "perfect knowledge" of patch profitability and that patch choice maximizes fitness. How foragers assess patch profitability has been debated extensively. One assessment strategy may be the use of past experience with a patch. Under stable environmental conditions, this strategy enhances fitness. However, in a highly unpredictable environment, past experience may provide inaccurate information about current conditions. Thus, in a nonstable environment, a strategy that allows rapid adjustment to present circumstances may be more beneficial. Evidence for this type of strategy has been found in individual choice. In the present experiments, a flock of pigeons foraged at two patches for food items and demonstrated results similar to those found in individual choice. Experiment 1 utilized predictable and unpredictable sequences of resource ratios presented across days or within a single session. Current foraging decisions depended on past experience, but that dependence diminished when the current foraging environment became more unpredictable. Experiment 2 repeated Experiment I with a different flock of pigeons under more controlled circumstances in an indoor coop and produced similar results.

Animals↗
PubMedDate not supplied

Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent.

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.

Animals↗
PubMed2006

Compost, manure, and gypsum application to timothy/red clover forage.

Some of the most fertile agricultural land in Atlantic Canada includes dykelands, which were developed from rich salt marshes along the Bay of Fundy through the construction of dykes. A 2-yr field experiment was conducted on dykeland soil to evaluate the effect of fertility treatments: source-separated municipal solid waste (SS-MSW) compost, solid manure, commercial fertilizer, and gypsum on (1) timothy/red clover forage productivity, (2) N, S, and other nutrients uptake, and (3) residual NO(3)-N and NH(4)-N in the soil profile. All fertility treatments increased dry matter yields from the two cuts each year relative to the control. Residual soil NO(3)-N and NH(4)-N concentrations in the fall of the second year decreased with depth, and beyond 20-cm depth were lower than 1 mg kg(-1). Gypsum application equivalent to 40 kg S ha(-1) increased dry matter yields and N uptake by forage, and increased soil Mehlich 3-extractable S, tissue S, and uptake of S, Ca, P, Cu, Fe, and Mn relative to the control. High rates of compost can provide sufficient N, S, and perhaps other nutrients to a perennial forage system under the cool wet climate of Atlantic Canada with no heavy metal enrichment of forage. However, the chemical N provided greater total N uptake than organic sources, except the high rate of compost, suggesting that the N availability from organic sources was not well synchronized with forage N demand. Municipal solid waste compost may also increase soil and forage tissue Na, which might be of concern.

Agriculture↗
PubMed2007

Five year-round forage systems in a dairy effluent sprayfield: phosphorus removal.

In northern Florida, forages are grown in dairy effluent sprayfields to recover excess P. Our purpose was to evaluate five year-round forage systems for their capacity to remove P from a dairy sprayfield. The soil is a Kershaw sand (thermic, uncoated Typic Quartzipsamment). Systems included bermudagrass (Cynodon spp.)-rye (Secale cereale L.) (BR), perennial peanut (Arachis glabrata Benth.)-rye (PR), corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye (CSR), corn-bermudagrass-rye (CBR), and corn-perennial peanut-rye (CPR). Forages were grown for five 12-mo cycles. Effluent P rates were 80, 120, and 165 kg ha-1 cycle-1. The 5-cycle P removal was 67 kg ha-1 cycle-1 for BR, 54 kg ha-1 for CBR, 52 kg for CSR, 45 kg for PR, and 43 for CPR. Removal of P by winter rye was low. There were differences in system rankings among cycles primarily due to changes in the performance of perennial forages. In the first two cycles, BR had the greatest P removal (91 kg ha-1 cycle-1) due to high bermudagrass yield and P concentration. In the first cycle, P removal was lowest for PR (36 kg ha-1) because perennial peanut was slow to establish. In later cycles, P removal for BR declined because bermudagrass yield and P concentration declined. It increased for PR because peanut yield increased. The yield of corn in CBR, CPR, and CSR was consistently high but P concentration was modest (avg. 2.2 g kg-1). Sorghum produced moderate but stable yield and had low P levels (avg. 1.8 g kg-1). Effluent rate marginally affected the performance of most grasses. For P recovery in dairy sprayfields in northern Florida, the best warm-season forage would likely be a high yielding, persistent bermudagrass.

Animal Feed↗
PubMed1991

Effects of milk intake on forage intake and performance of suckling range calves.

A study to examine the relationships between milk intake, forage intake, and performance of Hereford-Angus suckling range calves was conducted during July, August, and September of 1984 and 1985. Twenty calves were used each year. The study was conducted at the Red Bluff Research Ranch located 56 km west of Bozeman, Montana. Average daily gain, milk intake (MI), forage digestibility, and fecal output (FO) were measured at 28-d intervals, beginning when the average calf age was 66 +/- 4 d. Milk intake was estimated using weigh-suckle-weigh techniques. Total fecal collections were used to measure FO. Forage digestibility and rates of passage were determined using nylon bag in situ techniques and external markers in ruminally cannulated calves of the same age. Fecal output by calves increased as body weight and age increased. Milk intake was higher (P less than .05) in 1985 than in 1984, but FO was higher (P less than .01) in 1984 than in 1985. Fecal output by calves was negatively correlated to MI in July (r = -.62; P less than .05) and August (r = -.56; P less than .05). No significant correlations were detected between MI and ADG (P greater than .10). Forage intake estimates were derived from FO, rate of passage, and in situ digestibility values. During July, calves consumed .3 kg more forage for each kilogram of reduction in fluid MI (P less than .05). In both August and September, calves consumed .6 kg more forage for each kilogram of reduction in fluid MI (P less than .10). Calves maintained similar digestible energy (DE) intake both years, although the source of DE varied.

Animal Feed↗
PubMed1993

Beef cattle performance and forage characteristics of continuous, 6-paddock, and 11-paddock grazing systems.

Heifer performance, diet composition, and forage composition were compared during rotational and continuous grazing of mixed pasture (alfalfa, tall fescue, orchardgrass). One hundred eighteen yearling heifers were used to compare the three grazing systems during 2 yr. Treatments included continuous (CONT), 6-paddock rotational (6-PADD), and 11-paddock rotational grazing (11-PADD). Rotational paddocks were grazed for 6 d (6-PADD) and 3 d (11-PADD). All rotational paddocks were rested for 30 d. Put-and-take heifers were used to maintain forage availability and measure stocking rate. Forage availability was determined using a rising-plate meter. One ruminally fistulated heifer grazed each pasture during the 1st yr to obtain composition estimates from reticulorumen evacuation samples. Standing forage was sampled before and after grazing to obtain forage availability and nutrient composition during the 1st yr. Daily gain did not differ (P > .5) among treatments. Rotationally grazed pastures had higher (P < .05) stocking rates than CONT. Gain per hectare for 6-PADD was 40% greater (P < .05) for the CONT, and gain per hectare for 11-PADD tended to be higher (34%) (P = .06) than that for CONT. Organic matter intakes expressed as a percentage of BW did not differ (P > .4) among treatments. Diet quality and forage digestibility were similar among treatments. Rotational grazing increased beef production per hectare by increasing stocking rate without decreasing daily gain or diet quality compared with a continuous grazing system.

Animal Feed↗
PubMed1994

Interaction of forage level and monensin in diets for feedlot cattle on growth performance and digestive function.

A feedlot growth-performance trial and a metabolism trial were conducted to evaluate the interaction of forage level (10 vs 20%) and monensin (0 vs 28 mg/kg, air-dry basis) on utilization of a steam-flaked corn-based finishing diet. There were no treatment interactions (P > .10) on feedlot cattle growth performance or site and extent of digestion of OM, ADF, N, and starch. Monensin supplementation did not influence (P > .10) ADG, DM intake, feed efficiency, estimated NE value of the diet, or ruminal and total tract digestibility of OM, ADF, and starch. Monensin decreased (14.5%, P < .10) passage of microbial N to the small intestine and ruminal digestion of feed N (10.4%, P < .05). Ruminal pH tended to be slightly lower (1.9%, P < .10) with monensin supplementation. Monensin did not affect (P > .10) ruminal molar proportions of acetate and butyrate. There was an interaction between forage level and monensin on ruminal molar proportions of propionate. With the low-forage diet, molar proportions of propionate were 9.4% higher with monensin supplementation. In contrast, with the high-forage diet ruminal molar proportions of propionate were 5.5% lower with supplemental monensin. Monensin did not affect (P > .10) estimates of methane production. Decreasing the forage in the diet from 20 to 10% increased ADG (10.8%, P < .10), feed efficiency (11.6%, P < .01), and diet NEg (11.3%, P < .05). Ruminal digestibility of ADF, OM, and starch were not affected (P > .10) by forage level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1995

Characteristics of plant cell walls affecting intake and digestibility of forages by ruminants.

Even under the intensive concentrate feeding systems of ruminant animal production in the United States, forages continue to represent the single most important feed resource. Cell-wall concentration and digestibility limit the intake potential and energy availability of forage crops in beef and dairy production. Identification of cell-wall characteristics that should be targets of genetic modification is required if plant breeders and molecular biologists are to successfully improve forages for livestock feeding. As the forage plant cell develops, phenolic acids and lignin are deposited in the maturing cell wall in specific structural conformations, and in a strict developmental sequence. Lignin is the key element that limits cell-wall digestibility, but cross-linkage of lignin and wall polysaccharides by ferulic acid bridges may be a prerequisite for lignin to exert its affect. Lignin composition and p-coumaric acid in the wall are less likely to affect digestibility. Voluntary intake of forages is a critical determinant of animal performance and cell-wall concentration is negatively related to intake of ruminants consuming high-forage diets. Cell walls affect intake by contributing to ruminal fill. A simple model of cell-wall digestion and passage in which ruminal fill is a function of rates of digestion and passage, as well as the indigestible fraction of the cell-wall indicates that cell-wall concentration and rate of passage are the most critical parameters determining ruminal fill. Plant factors that affect rate of passage include those that affect particle size reduction by chewing and those that affect particle buoyancy in the rumen. The latter is primarily affected by 1) the ability of the particulate matter to retain gases, which is probably related to plant anatomy and rate of digestion of the plant tissue, and 2) the rate at which the gas is produced, which is affected by the potentially digestible fraction of the particulate matter and the rate of digestion of this fraction. Increasing rate of digestion should increase rate of passage by diminishing the gas produced and increasing density over time. A reduction in the indigestible cell-wall fraction is beneficial because this will decrease fill and increase digestibility. Animal production and economic benefits from reduced cell-wall concentration and increased digestibility are significant. Because of the high cell-wall concentration and large digestible cell-wall fraction of grasses, reduction in cell-wall concentration would probably be of greater value than improving digestibility in these species. Legumes represent the opposite situation and may benefit more from improvements in the digestibility of their cell walls.

Animal Feed↗
PubMed1996

Effect of enzyme preparations on in situ and in vitro degradation and in vivo digestive characteristics of mature cool-season grass forage in beef steers.

In situ and in vitro studies with a 3 x 2 x 5 factorial arrangement of treatments with an added untreated control evaluated three enzyme preparations, two levels of enzyme, and five moisture conditions of grass forage. Enzyme preparations predominantly contained cellulase and xylanase and will be designated as enzyme 1 (E1), enzyme 2 (E2), and a 50:50 combination of E1 and E2 (E1E2). The five moisture conditions included fresh, wilted, dried and rehydrated to fresh, dried and rehydrated to wilt, and dried grass. Addition of the high level of E1E2 to dried grass improved (P < .05) in vitro DM (43.5 vs 38.7%) and NDF (31.1 vs 26.0%) disappearance (48 h incubation) compared with the control treatment. Also, IVDMD was greater (P < .05) for the low level of E1 applied to wilted grass compared with the control. No other enzyme application improved in situ or in vitro disappearance of substrate over the control. In vivo responses of enzyme treatments found most likely to be effective from degradability studies were measured using four ruminally cannulated steers in a 4 x 4 Latin square experiment. Treatments examined were E1 applied to fresh forage, then dried; E1 applied to wilted forage, then dried; E1E2 applied to dry forage immediately before feeding (E-dry), and untreated forage (control). All forage treatments were harvested as dry hay. Total diet and hay DM intakes were greater (P < .05) for the E-dry than for the control diet. Rate of in situ NDF disappearance and total tract DM and NDF digestibility were greater (P < .05) for the E-dry than for the other treatments. Ruminal fluid ammonia N concentration, total VFA concentration, and pH were not altered (P > .10) by dietary treatment. Ruminal particulate passage rate was greater (P < .05) and ruminal retention time was shorter (P < .05) for the E-dry than for the control treatment. Data from this study suggest that addition of fibrolytic enzymes to grass hay before feeding has the potential to enhance intake and digestion.

Analysis of Variance↗
PubMed1997

The utilization of multidimensional scaling to identify forage characteristics associated with preference in sheep.

Forage preference is difficult to assess but is likely an important factor in determining DM intake. In two experiments, six sheep (wethers, Exp. 1; ewes, Exp. 2) were used to obtain preference ratings on nine hays (Exp. 1) or nine fresh forages (Exp. 2). The statistical procedure of multidimensional scaling was used to develop orthogonal dimensions to account for the observed variation in preference for hays and fresh forages. This analysis produced three dimensions that accounted for 54% of the variation in mean 3-d preference for hays (Exp. 1). The three dimensions were subsequently associated by regression analysis with seven compositional variables. These were IVDMD and concentrations of monosaccharides, short-chain polysaccharides (SCP), and disaccharides in dimension 1(R2 = .99); acid detergent insoluble ash (ADIA) concentration, monosaccharide and SCP concentrations, and masticate NDF in dimension 2 (R2 = .99); and disaccharide and starch concentrations in dimension 3 (R2 = .65). Three dimensions accounting for 51% of the variation in fresh forage preference were found and related to four variables by regression analysis. These were disaccharide concentration and median particle size in dimension 1 (R2 = .76) and starch and monosaccharide + disaccharide concentrations in dimension 3 (R2 = .97). No physicochemical variables analyzed in this study were found to be significantly associated with the coordinates for the forages in dimension 2. Multidimensional scaling accounted for more than half the observed variation in animal preference and, in all but one case, these dimensions could be associated with physicochemical characteristics of the forages.

Algorithms↗
PubMed1998

Potential of stockpiled perennial forages in winter grazing systems for pregnant beef cows.

We conducted a 3-yr study to measure herbage masses and chemical compositions of stockpiled perennial forages and corn crop residues and compare performance of cows grazing these forages or maintained in a drylot during winter. Midgestation, mature, medium-framed crossbred beef cows (mean BW, 506 kg; mean condition score, 5.3) 1) strip-grazed replicated fields containing stockpiled tall fescue-alfalfa, 2) strip-grazed stockpiled smooth bromegrass without (yr 1) and with (yr 2 and 3) red clover, 3) strip-grazed corn crop residues at 1.2 cows/ha, or 4) they were confined in a drylot for 129 to 141 d. All cows were offered grass-legume hay as large round bales to maintain a condition score of 5 on a 9-point scale. Mean initial amounts (P < .05) and daily changes (P < .01) of OM mass were greater in corn crop residues than in stockpiled perennial forages during the winter grazing seasons. Initial in vitro organic matter disappearance (IVOMD) and CP concentrations were greater (P < .05) and initial NDF, ADF, and ADIN concentrations in stockpiled forages were lower (P < .01) than those in corn crop residues. Mean changes in IVOMD, CP, NDF, and ADF concentrations during the grazing season were -.09, -.004, .10, and .11 percentage units OM/d, and they did not differ (P > .05) among forage species or grazed and nongrazed areas. Cows grazing stockpiled tall fescue-alfalfa had greater (P < .05) BW gains than those in other systems and greater (P < .05) body condition score increases than cows grazing corn crop residues. Because cows grazed stockpiled tall fescue-alfalfa, smooth bromegrass-red clover, and corn crop residues for 85, 83, and 57 d before beginning hay supplementation, cows grazing these forages required 1,069, 1,031, and 627 kg/cow less hay DM to maintain body condition than cows confined in a drylot.

Animal Feed↗
PubMed1999

Processing, mixing, and particle size reduction of forages for dairy cattle.

Adequate forage amounts in both physical and chemical forms are necessary for proper ruminal function in dairy cows. Under conditions in which total amounts of forage or particle size of the forage are reduced, cows spend less time ruminating and have a decreased amount of buoyant digesta in the rumen. These factors reduce saliva production and allow ruminal pH to fall, depressing activity of cellulolytic bacteria and causing a prolonged period of low ruminal pH. Insufficient particle size of the diet decreases the ruminal acetate-to-propionate ratio and reduces ruminal pH. The mean particle size of the diet, the variation in particle size, and the amount of chemical fiber (i.e., NDF or ADF) are all nutritionally important for dairy cows. Defining amounts and physical characteristics of fiber is important in balancing dairy cattle diets. Because particle size plays such an important role in digestion and animal performance, it must be an important consideration from harvest through feeding. Forages should not be reduced in particle size beyond what is necessary to achieve minimal storage losses and what can be accommodated by existing equipment. Forage and total mixed ration (TMR) particle sizes are potentially reduced in size by all phases of harvesting, storing, taking out of storage, mixing, and delivery of feed to the dairy cow. Mixing feed causes a reduction in size of all feed particles and is directly related to TMR mixing time; field studies show that the longest particles (>27 mm) may be reduced in size by 50%. Forage and TMR particle size as fed to the cows should be periodically monitored to maintain adequate nutrition for the dairy cow.

Animal Feed↗