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PubMed1991

Protein selection and avoidance strategies of contemporary and ancestral foragers: unresolved issues.

During seasonal or inter-annual periods of food shortage and restricted total calorie intake, ethnographically and ethnohistorically documented human foragers, when possible, under-utilize foods that are high in protein, such as lean meat, in favour of foods with higher lipid or carbohydrate content. Nutritional studies suggest that one reason for this behaviour stems from the fact that pregnant women, particularly at times when their total calorie intake is marginal, may be constrained in the amount of energy they can safely derive from protein sources to levels below about 25% of total calories. Protein intakes above this threshold may affect pregnancy outcome through decreased mass at birth and increased perinatal morbidity and mortality. This paper briefly outlines the evidence for the existence of an upper safe limit to total protein intake in pregnancy, and then discusses several facets of the issue that remain poorly understood. The paper ends by raising two basic questions directed especially toward specialists in primate and human nutrition: is this protein threshold real and demographically significant in modern human foraging populations? If so, does an analogous threshold affect pregnant female chimpanzees? If the answer to both of these questions is yes, we can then begin to explore systematically the consequences such a threshold might have for the diet and behaviour of early hominids.

Animals↗
PubMed1993

Analysis of bacterial phospholipid markers and plant monosaccharides during forage degradation by Ruminococcus flavefaciens and Fibrobacter succinogenes in co-culture.

Marker components of the phospholipids of Ruminococcus flavefaciens and Fibrobacter succinogenes were identified for studies on the degradation of forage by these bacteria growing in mixed culture. The principal fatty acid methyl esters and dimethyl acetals detected varied between strains and were influenced by the addition of a mixture of higher volatile fatty acids and vitamins to the medium, but these effects were small compared to the differences between the species. When two strains of R. flavefaciens were grown on a mixture of clover and ryegrass, and on barley straw in the presence or absence of two strains of F. succinogenes, the solubilization of plant material tended to be lowered by the presence of F. succinogenes. R. flavefaciens was the predominant bacterium among colonies recovered from roll tubes, and the phospholipids were primarily those of R. flavefaciens. Analysis of the culture supernatant liquids showed that F. succinogenes produced greater amounts of free and bound xylose from both clover and straw than did R. flavefaciens. With both forages, cultures containing the two species produced more soluble free arabinose, and less soluble-bound arabinose, than either species grown alone.

Animal Feed↗
PubMed2005

Scale-free movement patterns arising from olfactory-driven foraging.

The scale-free movement patterns of some foragers has aroused considerable excitement because they are known to optimize the success of random searches when target sites are randomly and sparsely distributed. Here it is shown that scale-free movement patterns can arise from a naive response of foragers to scent concentrations within turbulent plume structures.

Animals↗
PubMed1990

Purification and thermal dependence of glutathione reductase from two forage legume species.

Alfalfa (Medicago sativa L.) and sainfoin (Onobrychis viciifolia Scop.) are forage legumes that differ in their responses to high and low temperature stresses. Thermal limitations on the function of glutathione reductase (EC 1.6.4.2) could adversely affect the ability of the plant to cope with adverse temperatures. Our objectives were to (a) purify glutathione reductase from ;Cimarron' alfalfa and ;PI 212241' sainfoin and (b) investigate the intraspecies variation in the thermal dependency of glutathione reductase from each of three cultivars of alfalfa and two cultivars and an introduction of sainfoin. Glutathione reductase was purified 1222-and 1948-fold to a specific activity of 281 and 273 units per milligram of protein, from one species each of alfalfa and sainfoin, respectively. The relative molecular mass of the protein was approximately 140 kilodaltons with subunits of 57 and 37 kilodaltons under denaturing conditions. The activation energies were approximately 50 kilojoules per mole for both species. Over a 5 to 45 degrees C temperature gradient, large variation among species and genotypes within species was found for: (a) the minimum apparent Michaelis constant (0.6-2.1 micromoles of NADPH), (b) the temperature at which the minimum apparent Michaelis constant was observed (10-25 degrees C), and (c) the thermal kinetic windows (6-19 degrees C width). Future studies will focus on relating the thermal dependence of the Michaelis constant of the glutathione reductases and plant growth rates and forage quality of these species throughout the growing season.

Journal Article↗
PubMed2006

Breeding birds on small islands: island biogeography or optimal foraging?

1. We test MacArthur and Wilson's theory about the biogeography of communities on isolated habitat patches using bird breeding records from 16 small islands off the coasts of Britain and Ireland. 2. A traditional examination of patterns of species richness on these islands suggests that area and habitat diversity are important predictors, but that isolation and latitude have a negligible impact in this system. 3. Unlike traditional studies, we directly examine the fundamental processes of colonization and local extinction (cessation of breeding), rather than higher-order phenomena such as species richness. 4. We find that many of MacArthur and Wilson's predictions hold: colonization probability is lower on more isolated islands, and extinction probability is lower on larger islands and those with a greater diversity of habitats. 5. We also find an unexpected pattern: extinction probability is much lower on more isolated islands. This is the strongest relationship in these data, and isolation is the best single predictor of colonization and extinction. 6. Our results show that examination of species richness alone is misleading. Isolation has a strong effect on both of the dynamic processes that underlie richness, and in this system, the reductions in both colonization and extinction probability seen on more distant islands have opposing influences on species richness, and largely cancel each other out. 7. We suggest that an appropriate model for this system might be optimal foraging theory, which predicts that organisms will stay longer in a resource patch if the distance to a neighbouring patch is large. If nest sites and food are the resources in this system, then optimal foraging theory predicts the pattern we observe. 8. We advance the hypothesis that there is a class of spatial systems, defined by their scale and by the taxon under consideration, at which decision-making processes are a key driver of the spatiotemporal dynamics. The appropriate theory for such systems will be a hybrid of concepts from biogeography/metapopulation theory and behavioural ecology.

Animals↗
PubMed2006

Odour-mediated long-range avoidance of interspecific competition by a solitary endoparasitoid: a time-saving foraging strategy.

1. In studies on optimal foraging strategies, long-range decisions in the pursuit of resource are rarely considered. This is also the case for sympatric parasitoids, which may be confronted with the decision to accept or reject host larvae that are already parasitized by a competing species. They can be expected to reject already parasitized hosts if it is likely that they will lose the resulting intrinsic competition. However, examples of such interspecific host discrimination are rare. 2. We propose that parasitoids that are not egg-limited should reject inferior hosts only if it saves them time, and that this will be achieved mainly when the parasitoids are able to detect competitors from a distance. We tested this hypothesis using the sympatric parasitoids Cotesia marginiventris (Cresson) and Campoletis sonorensis (Cameron). 3. C. sonorensis was found to be the superior intrinsic competitor but, upon contact with a host larva, both wasps readily accepted hosts that had already been parasitized by the other species. However, in an olfactometer experiment, C. marginiventris females were found to strongly avoid the odour of their superior competitor. 4. These results are in accordance with a time optimization scenario, whereby the inferior competitor accepts competition if it costs only an egg, but avoids competition if it may save time that can be allocated to the search for more profitable hosts. 5. Models on host discrimination strategies in parasitoids had not yet considered discrimination from a distance. Long-range foraging decisions can also be expected for other organisms that have to choose between resources of varying suitability and profitability.

Animals↗
PubMed2007

Herbivore-induced plant volatiles as cues for habitat assessment by a foraging parasitoid.

1. Animals usually require information about the current state of their habitat to optimize their behaviour. For this, they can use a learning process through which their estimate is continually updated according to the cues they perceive. Identifying these cues is a long-standing but still inveterate challenge for ecologists. 2. The use of plant cues by aphid parasitoids for the assessment of habitat profitability and the adaptation of patch exploitation was studied. Grounding on predictions from optimal foraging theory, we tested whether parasitoids exploited host patches less intensively after visiting heavily infested plants than after visiting plants bearing fewer aphids. 3. As predicted, after visiting heavily infested plants parasitoids reduced their residence time and attacked fewer hosts in the next patch. This was the case regardless of whether the aphids were actually present on the first plant, indicating that the cue came from the plant. Moreover, the level of infestation of a plant at some distance from the first plant visited affected parasitoid patch exploitation on the second plant in a similar manner, indicating that the cue was volatile. 4. These results highlight a novel role of herbivore-induced volatiles in parasitoid foraging behaviour, different from the widely studied attraction at a distance.

Animals↗
PubMed2006

House dust and forage mite allergens and their role in human and canine atopic dermatitis.

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Allergens↗
PubMed2004

Brown seaweed- (Tasco) treated conserved forage enhances antioxidant status and immune function in heat-stressed wether lambs.

Twenty-seven wether lambs were utilized to evaluate select innate immunity and oxidative stress in response to diet and heat stress. Dietary treatments were: (i) control (tall fescue) hay = no Tasco (tradename for the extract of the brown seaweed, Ascophyllum nodosum, Acadian Sealants Ltd, Nova Scotia, Canada); (ii) pre-harvest Tasco-Forage-treated hay and (iii) control hay + post-harvest Tasco-EX. Tasco-Forage and Tasco-EX are two forms of the Tasco extract that are either applied to foliage or used for direct feeding, respectively. All lambs were supplemented with soyabean meal and trace mineralized salt. Heat stress was applied for 10 days with measurements obtained at days 0, 4 and 10. A heat x treatment interaction indicated hay with Tasco enhanced monocyte oxidative burst through short duration (p < 0.05) and long duration (p < 0.10) heat stress. Phagocytic activity was influenced by days of heat stress (p < 0.001) and treatment (p = 0.02) with post-harvest Tasco lambs exhibiting the greatest immune enhancement (p < 0.05). Red and white blood cell glutathione peroxidase increased by heat stress day 10 in Tasco lambs. Superoxide dismutase activity was increased and lipid hydroperoxide metabolites minimized (p < 0.01) through long duration heat stress in the pre-harvest Tasco group. Tasco treatment of tall fescue hay prior to harvest appears to provide residual effects on animal antioxidant availability in short-duration heat stress. Tasco supplementation to post-harvest fescue hay enhances immune function and protects against prolonged heat-induced oxidative stress.

Animal Feed↗
PubMed2006

Effects of amount of intake and stage of forage maturity on urinary allantoin excretion and estimated microbial crude protein synthesis in the rumen of steers.

Using ruminally cannulated steers, we investigated how urinary allantoin excretion was related to variations in feed intake and stage of forage maturity. Further, different approaches were compared for predicting ruminal microbial crude protein (MCP) synthesis and its efficiency. Experimental diets were arranged in a replicated 3 x 3 Latin square design (experiment 1) and a 4 x 4 Latin square design (experiment 2). In experiment 1, a mixed diet [forage to concentrate, 68:32 on a dry matter (DM) basis] was fed at three intake levels corresponding to 1, 1.5 and 2 times maintenance energy requirements. In experiment 2, four silage-based diets were fed based on perennial ryegrass (Lolium perenneL.), which was harvested at four maturity stages. Both experiments demonstrated the influence of diet on microbial growth rate and by this on efficiency of MCP synthesis, although the magnitude of the effects differed between approaches used for estimating MCP. Linear functions satisfactorily characterised the relationship between urinary allantoin excretion (y) and digestible organic matter (OM) intake (x, kg/day; experiment 1: y = 7.94 + 17.34 x; R(2) = 0.785) or intake of OM effectively degraded in the rumen (x, kg/day; experiment 2; y = 22.32 + 5.93 x; R(2) = 0.695). Urinary excretion of allantoin permitted a semi-quantitative prediction of MCP synthesis: ranking of diets and magnitude of changes in MCP synthesis were reflected.

Allantoin↗
PubMed2004

The dynamics of infant visual foraging.

Human infants actively forage for visual information from the moment of birth onward. Although we know a great deal about how stimulus characteristics influence looking behavior in the first few postnatal weeks, we know much less about the intrinsic dynamics of the behavior. Here we show that a simple stochastic dynamical system acts quantitatively like 4-week-old infants on a range of measures if there is hysteresis in the transitions between looking and looking away in the model system. The success of this simple three-parameter model suggests that visual foraging in the first few weeks after birth may be influenced more by noise and hysteresis in underlying neural mechanisms than by how infants process visual information after a look begins.

Attention↗
PubMed1984

Therapeutic effects of an imposed foraging task in disturbed monkeys.

A group of twelve bonnet macaques (Macaca radiata) raised in partial social isolation from birth to adulthood expressed moderate-to-severe behavioral disturbance as a function of their early rearing environments. The range of these behavioral function of their early rearing environments. The range of these behavioral abnormalities in this species are described for the first time. In order to assess the role of the current environment on their behavior, the animals as a group were required to obtain all of their food from a foraging device presenting two levels of difficulty. The therapeutic effect of the imposed foraging task was dependent upon the individual's status in the dominance hierarchy. Low- and high-ranking animals responded positively and became more social (338% above baseline levels) and showed lower levels of specific abnormal behaviors (nearly 75% lower). Mid-ranking animals responded negatively and became less social (89% lower), while their levels of abnormal behavior dramatically increased (200% higher).

Animals↗
PubMed2006

Prevalence of Escherichia coli O157:H7 and Salmonella in beef steers consuming different forage diets.

AIMS: To compare the prevalence of faecal shedding of Escherichia coli O157:H7 and Salmonella in growing beef cattle consuming various forages. METHODS AND RESULTS: In Experiment I, faecal samples were collected from steers grazing either endophyte-infected (E+) tall fescue or common bermudagrass (CB). Steers grazing E+ tall fescue were confined to a dry-lot pen and fed CB hay ad libitum for 10 days. In Exp. II, faecal samples were collected from steers grazing either E+ or novel endophyte-infected (NE) tall fescue and treated with one of two anthelmintics: ivermectin (I) or fenbendazole (F). In Exp. I, prevalence of E. coli O157:H7 was less in E+ tall fescue steers fed CB hay than steers grazing CB. More I-treated steers shed Salmonella than F-treated steers at 42-day postanthelmintic treatment but shedding of Salmonella was similar between anthelmintics at day 63 in Exp. II. CONCLUSIONS: Faecal shedding of pathogenic bacteria was not affected by grazing E+ tall fescue. Alterations of forage diets may influence the prevalence of E. coli O157:H7, and anthelmintic treatment could affect faecal shedding of Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge of factors that influence shedding of pathogenic bacteria in cattle is necessary to develop on-farm intervention strategies aimed at reducing pathogen shedding.

Animal Feed↗
PubMed2005

Risks associated with environmental enrichment: intestinal obstruction caused by foraging substrate.

Questions are occasionally asked about the safety of enrichment techniques, considering that many novel ways are frequently employed to ensure environmental complexity. A juvenile male vervet monkey was found with a phytobezoar of straw obstructing the sigmoid colon. The straw was foraging substrate, which is used in communal cages. Due to the extent of the resulting necrosis in the sigmoid and descending colon, the monkey had to be killed. This is the only individual to have suffered a harmful effect from the foraging substrate from amongst 120 vervet monkeys, which have been permanently housed on straw for over 5 years.

Animals↗
PubMed1999

The effects of timing and amount of forage and grain on exercise response in thoroughbred horses.

There is considerable debate among horsemen about how to feed horses before exercise. Should horses be fed or fasted before work and when should hay be fed relative to grain and/or exercise? Three experiments were conducted to evaluate if feeding hay with and without grain affects glycaemic and haematological responses in Thoroughbred (TB) horses at rest and during a simulated competition exercise test (CET) on a high-speed treadmill. In Experiment 1, 6 TB horses were fed hay at 3 different times relative to a grain meal. Time of feeding hay affected glycaemic response, plasma protein and water intake post grain feeding. During Experiment 2, 4 TB horses were used in a 4 x 4 Latin square design to determine whether feeding grain with or without hay prior to a CET would affect substrate utilisation and exercise. Feeding grain reduced free fatty acid (FFA) availability and increased blood glucose disappearance during exercise (P < 0.05). Feeding hay either along with grain or ad libitum the night before exercise resulted in reduced plasma volume (P < 0.05) and higher lactate production (P < 0.05) and heart rates (P < 0.05) during exercise. During Experiment 3, 4 TB horses were used in a 4 x 4 Latin square design experiment to determine whether feeding forage but no grain prior to CET would affect substrate utilisation and performance. Feeding only forage before exercise did not adversely affect performance. It was concluded that grain should be withheld from horses before exercise, but that small quantities of hay should be fed to ensure proper gastrointestinal tract function.

Animals↗
PubMed2005

Whistles of small groups of Sotalia fluviatilis during foraging behavior in southeastern Brazil.

Whistle emissions were recorded from small groups of marine tucuxi dolphins (Sotalia fluviatilis) in two beaches located in an important biological reserve in the Cananéia estuary (25 degrees 03'S, 47 degrees 58'W), southeastern Brazil. A total of 17 h of acoustic data was collected when dolphins were engaged in a specific feeding foraging activity. The amount of 3235 whistles was recorded and 40% (n=1294) were analyzed. Seven acoustic whistle parameters were determined: duration (ms), number of inflection points, start and end frequency (kHz), minimum and maximum frequency (kHz), and frequency range (kHz). Whistles with up to four inflection points were found. Whistles with no inflection points and rising frequency corresponded to 85% (n=1104) of all analyzed whistles. Whistle duration varied from 38 to 627 ms (mean=229.6+/-109.9 ms), with the start frequency varying between 1 and 16 kHz (mean=8.16+/-3.0 kHz) and the end frequency between 2 and 18 kHz (mean=14.35+/-3.0 kHz). The importance of this study requires an accurate measurement of the whistles' emissions in an unusual foraging feeding behavior situation on two beaches where several tucuxis, mostly mother-calf pairs, are frequently present. These two beaches are located in a federal and state environment Environmental Protected Area threatened by the progressive increase of tourism.

Animals↗
PubMed1976

Ultrastructure of rumen bacterial attachment to forage cell walls.

The degradation of forage cell walls by rumen bacteria was investigated with critical-point drying/scanning electron microscopy and ruthenium red staining/transmission electron microscopy. Differences were observed in the manner of attachment of different morphological types of rumen bacteria to plant cell walls during degradation. Cocci, constituting about 22% of the attached bacteria, appeared to be attached to degraded plant walls via capsule-like substances averaging 58 nm in width (range, 21 to 84 nm). Many bacilli appeared to adhere to forage substrates without distinct capsule-like material, although unattached bacteria with capsules were observed occasionally. Certain bacili appeared to be attached to degraded tissue via small amounts of extracellular material, but others apparently had no extracellular material. Bacilli with a distinct morphology due to an irregularly folded, electron-dense outer layer or layers (about 15 nm thick) and without fibrous extracellular material consituted about 37% of the attached bacteria and were observed to adhere so closely to degraded plant walls that the bacterial shape conformed to the shape of the degraded zone. In the rumen ecosystem, bacteria appeared to adhere to plant substrates during degradation by capsule-like material and by small amounts of extracellular material, as well as by the other means not observable by electron microscopy.

Animal Feed↗
PubMed1980

Evaluation by electron microscopy and anaerobic culture of types of rumen bacteria associated with digestion of forage cell walls.

Different morphological types of rumen bacteria which degraded cell walls of forage grasses with various in vitro digestibilities were evaluated with electron microscopy. The majority of these bacteria (i.e., about 70% or more) consisted of two distinct types: (i) encapsulated cocci and (ii) irregularly shaped bacteria, resembling major fiber digesters found in the rumen. Each type was capable of degrading structurally intact cell walls. Differences (P less than or equal to 0.02) in the percent ratio of encapsulated cocci to irregularly shaped bacteria were observed between Bermuda grass and fescue; the ratio of encapsulated cocci to irregularly shaped bacteria between Bermuda grass and orchard grass was similar and variations were high. The proportion of irregularly shaped bacteria usually increased with increased time of digestion. Differences (P greater than 0.1) were not found in the percentage ratio of encapsulated cocci to irregularly shaped bacteria attached to specific tissue types in either Bermuda grass or fescue. However, encapsulated cocci tended to be more prevalent on sclerenchyma than other tissues in Bermuda grass, but less prevalent on sclerenchyma than other tissues in fescue. Transmission electron microscopy of tissue digestion of rapidly degraded orchard grass blades revealed that mesophyll, parenchyma bundle sheath, and parts of the epidermal cell wall apparently were degraded without direct attachment of bacteria although bacteria were near the cell walls undergoing digestion. Anaerobic growth studies showed that the total culturable bacteria developing on medium 10 and media containing carbohydrates similar to those in forage cell walls (i.e., pectin, xylan, and cellobiose) were 80% higher from rumen bacterial populations adapted in vitro to cell walls of orchard grass compared to those from Bermuda grass; the number of colonies from the orchard grass-adapted population was significantly (P less than or equal to 0.05) greater on the medium containing xylan. Filter paper tests showed that the cellulolytic activity of populations adapted to fescue was greater than that of orchard grass or Bermuda grass.

Anaerobiosis↗