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PubMed1993

In situ dry matter, protein, and fiber degradation of perennial forages.

Eight forages (alfalfa, birdsfoot trefoil, red clover, bromegrass, orchardgrass, perennial ryegrass, quackgrass, and timothy) at three maturities were evaluated for ruminal DM, CP, and NDF degradation kinetics. Duplicate dacron bags were incubated for 0, 3, 6, 10, 13, 25, 48, and 72 h in two late lactation Holstein cows fitted with ruminal cannulas over eight experimental periods. Species and maturity effects were observed for soluble, slow, and undegraded fractions; degradation rate; and ruminally degradable DM, CP, and NDF. Significant species by maturity interactions also were evident for fractions and ruminal degradabilities of DM, CP, and NDF. Legumes exhibited more extensive ruminal DM degradation than did grasses. No clear trends were evident in rate of ruminal CP degradation between legumes and grasses. Mature grasses were lowest in ruminally degradable CP. Legumes exhibited a higher undegraded fraction and faster degradation rate of slowly degraded NDF fractions, resulting in similar ruminally degraded NDF for legumes and grasses. Extensive differences in ruminal degradation kinetics existed between perennial legume and grass species and maturities. Species by maturity interactions were diverse, making categorization of degradation characteristics of legumes and grasses difficult.

Animal Feed↗
PubMed1995

Responses of early lactation cows fed winter and summer annual forages and undegradable intake protein.

Twenty-four multiparous Holstein cows were divided into six blocks of 4 cows based on their previous 305-d mature equivalent milk yield and were used in a 2 x 3 factorial experiment for the first 84 DIM. Objectives were to determine the effects of forage and RUP supplementation of DM and nutrient intakes and digestibilities, milk yield and composition, BW change, and plasma concentrations of insulin, triiodothyronine, thyroxine, cortisol, NEFA, urea N, and protein. One cow from each block was assigned to wheat or sorghum silage plus one of three concentrates. Protein treatments were 1) all supplemental CP from soybean meal; 2) 33.3% of supplemental CP from heat soybean meal, fish meal, and corn gluten meal; and 3) protein treatment 2 plus an additional 4.6% CP from soybean meal. Intakes of DM, CP, NDF, ADF, NEL, and RUP were higher in cows fed sorghum silage; RUP tended to increase DMI. Milk and 3.5% FCM yields were higher for cows fed sorghum silage than for those fed wheat silage (42.3 vs. 40.0 kg/d and 41.2 vs. 38.7 kg/d, respectively). Milk protein, lactose, and SNF were increased by RUP. Insulin was increased, cortisol was decreased, and thyroid hormones were unaffected by RUP. Concentrations of NEFA were highest at wk 4. For early lactation cows fed diets containing sorghum or wheat silage, RUP is a necessity.

Animal Feed↗
PubMed1999

Effect of applying lactic acid bacteria isolated from forage crops on fermentation characteristics and aerobic deterioration of silage.

Two selected strains, Lactobacillus casei FG 1 and Lactobacillus plantarum FG 10 that were isolated from forage crops were used as additives at 1.0 x 10(5) cfu/g of fresh matter to alfalfa, Italian ryegrass, and sorghum, and their effect on fermentation characteristics and aerobic deterioration of silage was studied. The three silages treated with strains FG 1 or FG 10 were well preserved; had significantly lower pH values, butyric acid, propionic acid, and ammonia N concentrations, gas production, and dry matter losses; and had significantly higher contents of residual water-soluble carbohydrates and lactic acid than did the respective control silages. Yeast counts were high in all treated silages and increased rapidly during aerobic exposure. As a result, treated silages spoiled faster upon aerobic exposure than did the respective control silages. Most yeasts isolated from deteriorated silages showed high tolerance to lactic acid but low tolerance to butyric acid, and they were able to grow at low pH conditions and assimilate lactic acid. The results confirmed that L. casei and L. plantarum improved fermentation quality but did not inhibit the growth of silage yeast or aerobic deterioration of the silage.

Aerobiosis↗
PubMed1999

Effect of year and cutting on equations for estimating net energy of alfalfa forage.

The net energy of lactation (NEL) concentration of forages is important for formulating diets. The equations presently used to estimate NEL of alfalfa are based on limited data. Our objective was to determine whether a larger database would provide more relevant equations. One hundred eighty samples of alfalfa were taken over four cuttings and 2 yr, combined into 45 composites and analyzed for neutral detergent fiber, acid detergent fiber (ADF), and in vitro true digestibility. Finally, NEL values were estimated using neutral detergent fiber and in vitro true digestibility. Prediction equations were obtained by regressing NEL upon ADF concentration. Changes in NEL with age of alfalfa at harvest differed with year and cutting. Estimation of NEL would be more accurate with equations specific for cutting and year, but such an approach would be difficult to use in practice. When data were pooled across years, four cutting-specific equations were obtained; these had different intercepts and slopes and gave different NEL values for a given ADF content. Differences among estimates of NEL increased as ADF increased. Data were combined across years and cuttings to give an overall equation that was similar to published prediction equations. Compared with NEL values from the cutting-specific equations, the overall equation underestimated NEL for first cutting alfalfa and overestimated NEL of second cutting alfalfa. A lack of precision in estimating NEL could equate to 1.5 to 2.5 kg of milk/d. Cutting specific equations should be used to estimate the NEL of first- and second-cutting alfalfa; NEL of the third and fourth cuttings could be estimated using an overall equation.

Animal Nutritional Physiological Phenomena↗
PubMed2002

How does the ecological foraging behavior of desert kangaroo rats (Dipodomys deserti) relate to their behavior on radial mazes?

Experiment 1 showed that laboratory-reared desert kangaroo rats, like domestic Norway rats, efficiently search for food on a radial arm maze (RAM) by avoiding revisiting arms within a trial. By placing an RAM on the floor so the animals could approach food from any direction, Experiment 2 tested whether efficient search by kangaroo rats was based on tactics of distance minimizing, central-place foraging, trail following, or meandering. In contrast to the dominant trail-following tactic of domestic Norway rats (Hoffman, Timberlake, Leffel, & Gont, 1999), kangaroo rats tended to distance minimize, whether maze arms were present or not. Experiment 3 indicated that kangaroo rats treated a floor configuration of eight food cups as two patches of four, based on beeline travel between patches and meandering within them. We conclude that similar performance in an elevated RAM by different species can be based on different tactics, and we suggest that a laboratory apparatus can be used to cast light on niche-related mechanisms.

Animals↗
PubMed2004

Human foraging behavior in a virtual environment.

We have developed an experimental platform that allows a large number of human participants to interact in real time within a common virtual world. Within this environment, human participants foraged for resources distributed in two spatially separated pools. In addition to varying the relative replenishment rate for the two pools (50-50, 65-35, or 80-20), we manipulated whether the participants could see each other and the entire resource distribution or had their vision restricted to resources at their own location. Two empirical deviations from an optimal distribution of the participants were found. First, the participants were more scattered within a resource pool than the resources were themselves. Second, there was systematic underutilization of the richer pool. For example, the participants distributed themselves 73% and 27% to resource pools that had replenishment rates of 80% and 20%, respectively. In addition, there were oscillations in the harvesting rate of the pools across time, revealed by a Fourier analysis with prominent power near 50 sec per cycle. The suboptimalities and oscillations were more apparent when the locations of the participants and the food were not visible. Individual participant knowledge thus affects the efficiency with which a population of participants harvests resources.

Feeding Behavior↗
PubMed1999

Neuronal polymorphism among natural alleles of a cGMP-dependent kinase gene, foraging, in Drosophila.

Natural variation in neuronal excitability and connectivity has not been extensively studied. In Drosophila melanogaster, a naturally maintained genetic polymorphism at a cGMP-dependent protein kinase (PKG) gene, foraging (for), is associated with alternative food search strategies among the allelic variants Rover (for(R); higher PKG activity) and sitter (for(s); lower PKG activity). We examined physiological and morphological variations in nervous systems of these allelic variants isolated from natural populations. Whole-cell current clamping revealed distinct excitability patterns, with spontaneous activities and excessive evoked firing in cultured sitter, but not Rover, neurons. Voltage-clamp examination demonstrated reduced voltage-dependent K(+) currents in sitter neurons. Focal recordings from synapses at the larval neuromuscular junction demonstrated spontaneous activity and supernumerary discharges with increased transmitter release after nerve stimulation. Immunolabeling showed more diffuse motor axon terminal projections with increased ectopic nerve entry points in sitter larval muscles. The differences between the two natural alleles was enhanced in laboratory-induced mutant alleles of the for gene. The pervasive effects of the for-PKG on neuronal excitability, synaptic transmission, and nerve connectivity illustrate the magnitude of neuronal variability in Drosophila that can be attributed to a single gene. These findings establish the consequences in cellular function for natural variation in an isoform of PKG and suggest a role for natural selection in maintaining variation in neuronal properties.

Action Potentials↗
PubMed1999

Ammoniated forage poisoning: acute toxicity of newly identified dialkylimidazoles to inbred mice.

The i.p. acute toxicity of the dialkylimidazoles 1,2-dimethylimidazole, 1,4-dimethylimidazole, 1,5-dimethylimidazole, 2,4-dimethylimidazole and 2-ethyl-4-methylimidazole was investigated in C57B1 female mice, and compared to the toxicity of 4-methylimidazole (4-MI). An approximate median lethal dose protocol was applied designed to obtain a qualitative description of the clinical toxic effects and an estimate of the acute lethal dose with the use of a minimal number of animals. The approximate median lethal dose of the dialkylimidazoles varied from slightly above to 3-times greater than that of 4-MI. 1,4-Dimethylimidazole and 1,5-dimethylimidazole had tremorogenic and convulsive effects qualitatively similar to those of 4-MI. Testing a mixture of alkylimidazoles comparable to the composition found in toxic ammoniated forage or milk did not indicate any synergistic enhancement of the toxicity to mice.

Animal Feed↗
PubMed2000

Responses to chemical cues from animal and plant foods by actively foraging insectivorous and omnivorous scincine lizards.

If tongue-flicking is important to lizards to sample chemical cues permitting identification of foods, tongue-flicking and subsequent feeding responses should be adjusted to match diet. This hypothesis can be examined for plant foods because most lizards are insectivores, but herbivory/omnivory has evolved independently in many lizard taxa. Here we present experimental data on chemosensory responses to chemical cues from animal prey and palatable plants by three species of the scincine lizards. When tested with chemical stimuli presented on cotton swabs, the insectivorous Eumeces fasciatus responded strongly to prey chemicals but not to chemicals from plants palatable to omnivorous lizards or to pungent or odorless control stimuli. Two omnivorous species, E. schneideri and Scincus mitranus, responded more strongly to chemical cues from both prey and food plants than to the control chemicals. All available data for actively foraging lizards, including these skinks, show that they are capable of prey chemical discrimination, and insectivores do not exhibit elevated tongue-flicking or biting responses to chemical cues from palatable plants. In all of the several species of herbivores/omnivores tested, the lizards show elevated responses to both animal and plant chemicals. We suggest two independent origins of both omnivory and plant chemical discrimination that may account for the evolution of diet and food chemical discriminations in the eight species of skinks studied, five of which are omnivores. All data are consistent with the hypothesis that acquisition of omnivory is accompanied by acquisition of plant chemical discrimination, but data on a broad diversity of taxa are needed for a definitive comparative test of the evolutionary hypothesis. J. Exp. Zool. 287:327-339, 2000.

Animals↗
PubMed2000

Portal net appearance of amino acids in growing pigs fed a barley-based diet with inclusion of three different forage meals.

The net absorption of amino acids (AA) in young pigs fed a barley-based control diet (C) and diets where barley was replaced by 200 g/kg fresh weight of dried lucerne (Medicago sativa; L20), white clover (Trifolium repens; W20) or perennial ryegrass (Lolium perenne; PR20) meal was studied. Castrated male pigs were fitted with permanent catheters in the hepatic portal vein and mesenteric artery, and the hepatic portal net absorption of AA was estimated from the porto-arterial plasma concentration differences and the hepatic portal-vein blood flow. In general, the essential AA (EAA) concentrations in the hepatic portal vein reached peak levels 90 min after feeding and thereafter exhibited a transient decline. Maximum porto-arterial differences were reached between 1 and 3 h postprandially for most of the AA. The cumulative net absorption of non-essential AA (NEAA) and EAA did not differ significantly between the barley-based diet and diets W20 and PR20. Due to a lower intake of AA on diet L20, the cumulative net absorption of NEAA and EAA was significantly (P < 0.05) lower than diet C. With the exceptions of the EAA arginine, cystine and valine, and the NEAA glutamic acid + glutamine and glycine, there were no significant differences in the absorption coefficients for the EAA and NEAA between the diets. In addition, the pattern of the total EAA in the mixture absorbed postprandially did not differ significantly between the diets. The present study gives support to the contention that the replacement of barley AA with forage meal AA in a barley-based diet for growing pigs should be expected to result in minor differences in the net portal flux of AA.

Amino Acids, Essential↗
PubMed2000

Forager size of the leaf-cutting ant Atta sexdens (Hymenoptera: Formicidae) in a mature eucalyptus forest in Brazil.

We determined the size characteristics of foragers of the leaf-cutting ant Atta sexdens in a mature eucalyptus forest in Campos dos Goytacazes, Rio de Janeiro State, Brazil, at daytime (7:30 to 10:00 hr) and nighttime (19:00 to 23:00 hr). There were no significant differences between daytime and nighttime ant mass (Ma), but leaf fragment mass (Ml) and burden (B = [Ma + Ml]/Ma), which indicates relative load capacity, were significantly greater at daytime. There was a positive linear relationship between Ma and Ml for the combined daytime and nighttime data, and increases in Ma resulted in lower B. We compared A. sexdens characteristics with published results for Atta cephalotes, a closely related species. A. sexdens is larger and therefore able to carry heavier loads, but its burden is about 72% of the average value for A. cephalotes. We suggest that the lower load capacity of A. sexdens in comparison to A. cephalotes is related to its relatively larger size.

Animals↗
PubMedDate not supplied

Determination of crude protein in animal feed, forage, grain, and oilseeds by using block digestion with a copper catalyst and steam distillation into boric acid: collaborative study.

A collaborative study was conducted to evaluate the repeatability and reproducibility of an extension of AOAC Official Method 991.20, Nitrogen (Crude) in Milk, to animal feed, forage (plant tissue), grain, and oilseed materials. Test portions are digested in an aluminum block at 420 degrees C in sulfuric acid with potassium sulfate and a copper catalyst. Digests are cooled and diluted, and concentrated sodium hydroxide is added to neutralize the acid and make the digest basic; the liberated ammonia is distilled by using steam distillation. The liberated ammonia is trapped in a weak boric acid solution and titrated with a stronger standardized acid, hydrochloric acid; colorimetric endpoint detection is used. Fourteen blind samples were sent to 13 collaborators in the United States, Denmark, Sweden, Germany, and the United Kingdom. Recoveries of nitrogen from lysine, tryptophan, and acetanilide were 86.8, 98.8, and 100.1%, respectively. The within-laboratory relative standard deviation (RSDr, repeatability) ranged from 0.40 to 2.38% for crude protein. The among-laboratories (including within-) relative standard deviation (RSD(R), reproducibility) ranged from 0.44 to 2.38%. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL. A lower concentration (1% H3BO3) of trapping solution was compared with the concentration specified in the original protocol (4% H3BO3) and was found comparable for use in an automatic titration system in which titration begins automatically as soon as distillation starts. The Study Directors recommend that 1% H3BO3 as an optional alternative to 4% boric acid trapping solution be allowed for automatic titrators that titrate throughout the distillation.

Animal Feed↗
PubMedDate not supplied

[Quantity and frequency of pesticides in forage and animal foodstuffs in use in Italy].

The results of analytical investigations on pesticide residues in the forages and foodstuffs most commonly used in Italy are described. Examination of 9,056 samples, selected at random during the period spring 1970 to autumn 1974, showed that 17 pesticide residues could be identified by the gas chromatographic technique employed and described, with quite significant mean total concentrations. These residues, although not reaching levels to cause problems of acute toxicity, can upset the symbiosis balance in the alimentary tract and reduce the economic results from farm animals.

Animal Feed↗
PubMed2002

Foraging challenges of red colobus monkeys: influence of nutrients and secondary compounds.

The diet selection of two groups of red colobus monkeys (Procolobus badius) in Kibale National Park, Uganda are considered with respect to protein, fiber, digestibility, alkaloids, total phenolics, tannins, saponins, and cyanogenic glycosides. Both groups selected young leaves over mature leaves and young leaves had more protein, were more digestible, and had a higher protein to fiber ratio than mature leaves. Young and mature leaves did not differ with respect to secondary compounds. There were no differences in the phytochemical factors examined between frequently eaten foods and leaves that red colobus were never known to eat, but were relatively common in the environment. Regression analyses predicting foraging effort from the phytochemical components of the large group's diet revealed selection for only one factor, foods that are high in protein and low in fiber, when differences in food tree availability were taken into consideration. A similar analysis with the small group did not suggest selection or avoidance of foods with respect to any of the factors considered. Previous studies have found the biomass of folivorous primates to be related to the ratio of protein to fiber concentration of mature leaves in the environment. These investigations have considered variation in folivore biomass and forest composition among sites separated by hundreds of kilometers; however, large variation in folivore abundance occurs over much smaller spatial scales. In Kibale National Park the average protein to fiber ratio of the mature leaves of the 20 most abundant tree species predicted the biomass of red colobus among four neighboring sites. We examined the generality of this relationship by adding our biomass and leaf chemistry values to previously published values; 62% of the variance in colobine biomass was explained by variation in the protein to fiber ratios of mature leaves at the sites. There was no evidence that red colobus avoided plants with high levels of secondary compounds. In fact, one of the most preferred trees (Prunus africana) was the species with the highest levels of cyanogenic glycosides, and the highest saponin levels were found in the young leaves of Albizia grandibracteata, the sixth and fourth most preferred plant species for the large and small groups, respectively.

Alkaloids↗
PubMed2002

(Evolutionary) Theories of warfare in preindustrial (foraging) societies.

I present an inventory of theories of war causation (and on the origin of war) in preindustrial (traditional, foraging, 'primitive', hunter-gatherer, band- and tribe-level) societies, with emphasis on the roles of natural selection, sexual selection and kin selection. Also the school of sociocultural evolution is briefly discussed.

Biological Evolution↗
PubMed2003

Mercury effects on predator avoidance behavior of a forage fish, golden shiner (Notemigonus crysoleucas).

Mercury contamination of fish is widespread in North America and has resulted in the establishment of fish consumption advisories to protect human health. However, the effects of mercury exposure to fish have seldom been investigated. We examined the effects of dietary mercury exposure at environmental levels in a common forage species, golden shiner (Notemigonus crysoleucas). Fish were fed either an unaltered diet (12 ng/g wet wt methylmercury [MeHg] as Hg), a low-Hg diet (455 ng/g Hg), or a high-Hg diet (959 ng/g Hg). After 90 d mean fish whole-body total Hg concentrations were 41, 230, and 518 ng/g wet wt, respectively, which were within the range of concentrations found in this species in northern U.S. lakes. There were no mortalities or differences in growth rate among groups. Groups of fish from each treatment were exposed to a model avian predator and their behavioral response videotaped for analysis. Brain acetylcholinesterase (AChE) activity was determined in fish after behavioral testing. Fish fed the high-Hg diet had significantly greater shoal vertical dispersal following predator exposure, took longer to return to pre-exposure activity level, and had greater shoal area after return to pre-exposure activity than did the other treatments, all of which would increase vulnerability of the fish to predation. There were no differences in brain AChE among treatments. We conclude that mercury exposure at levels currently occurring in northern United States lakes alters fish predator-avoidance behavior in a manner that may increase vulnerability to predation. This finding has significant implications for food chain transfer of Hg and Hg exposure of fish predators.

Acetylcholinesterase↗
PubMedDate not supplied

Polliniferous plants and foraging strategies of Apis mellifera (Hymenoptera: Apidae) in the Yucatán Peninsula, Mexico.

A study of the most important polliniferous plants for European and Africanized honeybees (Apis mellifera L.) was made in Quintana Roo state. Comparisons were made between the plants visited by both bee types in order to determine whether there were qualitative or quantitative differences in their choice of plant species. Also some foraging strategies of the honeybees were analysed. Pollen from pollen load samples was acetolysed and mounted on slides. Subsequently the pollen grains were identified, counted and photographed. A total of 206 pollen load samples were collected at Palmas and St. Teresa during two years. The most frequent species in the pollen load samples from European and Africanized honeybees were Cecropia peltata, Metopium brownei, Lonchocarpus sp. 2, Viguiera dentata, Eragrostis sp. 1, Bursera simaruba and Eupatorium albicaule. Both types of honey bees show a high reliance on pollen from only a few species, the first five named above comprised around 50% of all the mean percentage frequencies. Families that contributed with the largest number of pollen species were Fabaceae, Asteraceae, Boraginaceae, Convolvulaceae, Euphorbiaceae, Sapindaceae, Poaceae, Myrtaceae, Sapotaceae and Tiliaceae. C. peltata, Trema micrantha, B. simaruba, Eugenia sp. 1, Thouinia canesceras, Pouteria sp. 1, Mimosa bahamensis and V. dentata, were the pollen species with the largest percentages of occurrence in both European and Africanized bee pollen load samples, and also represent a "long-term" food resources during the year.

Animals↗
PubMed1992

Ochratoxigenic moulds and ochratoxin A in forages and grain feeds.

The contamination of forages and grain feeds with ochratoxigenic moulds and ochratoxin A was examined. The investigations were carried out over a period of three years in all seasons. Feeds were found to be contaminated with moulds at a high level throughout the three research years. The highest percentage (95 to 100) of contaminated feed samples was noticed during the second year. Total viable counts of moulds established in 1 g of feed samples ranged from 0.5 to 7.8 x 10(6). Penicillium spp. were dominant in mycopopulations isolated from feeds. Ochratoxin-A producing moulds were present permanently. In the summer period of the second research year as much as 94% of the feed samples were contaminated by ochratoxigenic Penicillium species. P. verrucosum var. cyclopium P. verrucosum var. verrucosum, P. commune and P. chrysogenum, i.e. ochratoxin-producing moulds, were the most prevalent Penicillium species throughout the three-year investigation. Ochratoxin A was found in various feeds in all seasons, except in summer of the first research year. Concentrations of the toxin varied from traces to 400 micrograms/kg. It occurred consistently in the same types of feeds (hay, dried alfalfa, fresh alfalfa, concentrate, pelleted sugar beet pulp, corn silage).

Animal Feed↗