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Bioavailable phosphorus in runoff from alfalfa, smooth bromegrass, and alfalfa-smooth bromegrass.

Runoff from sloping landscapes cropped with established alfalfa (Medicago sativa L.) may contain bioavailable P (BAP) which accelerates eutrophication of surface water bodies. Such BAP exists as either dissolved reactive P (DRP) or bioavailable reactive particulate P (BPP). We hypothesized that before and after harvest, sod-forming smooth bromegrass (Bromus inermis Leyss.) or alfalfa-smooth bromegrass mixtures would have less BAP, DRP, and BPP runoff losses than taprooted alfalfa. Swards established in 1992 near Lancaster, WI were subjected to a 72 mm simulated rainfall applied for 1 h in 1993 and 1994 to forage regrowth at 4 and 6 wk after first harvest and immediately (0 wk) after second harvest. Hourly BAP losses for all sward types were 82% less when 1.5 Mg ha(-1) of forage dry matter was present. High DRP losses (>0.050 kg ha(-1)) were associated with high DRP concentrations (>7.1 micromol L(-1)) and high surface soil P concentrations (>59 mg kg(-1)) resulting from broadcast maintenance P fertilizer. High BPP losses (>0.035 kg ha(-1)) were associated with high runoff volumes (>24 mm) and sediment concentrations (>2 g L(-1)). Summed over all 6 rainfall simulations, total BAP loss was only 0.07 kg ha(-1) at the 6 wk stage of regrowth compared with 0.35 at 4 wk, and 0.41 at 0 wk. Moreover, there was no significant difference between sward types for DRP concentration, DRP loss, or BAP loss. We conclude that avoiding excessive defoliation was more effective at reducing BAP losses than specific forage species selection.

Agriculture↗

The effect of five forage species on transport and transformation of atrazine and isoxaflutole (balance) in lysimeter leachate.

A field lysimeter study with bare ground and five different ground covers was established to evaluate the effect of forage grasses on the fate and transport of two herbicides in leachate. The herbicides were atrazine (ATR; 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and isoxaflutole [IXF; 5-cyclopropyl-4-(2-methylsulfonyl-4-trifluormethyl-benzoyl)isoxazole], which has the commercial name Balance (Aventis Crop Science, Strasbourg, France). The ground covers included orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), and switchgrass (Panicum virgatum L.). The results suggested that the total IXF (parent + metabolites) showed higher mobility than ATR and its metabolites. Differences in the timing of transport reflected the rapid degradation of IXF to the more soluble, stable, and biologically active diketonitrile (DKN) metabolite in the system. Although grass treatments did not promote the hydrolysis of DKN, they significantly reduced its transport in the leachate through enhanced evapotranspiration. Grass treatments significantly enhanced ATR degradation in the leachates and soils, especially through N dealkylation, but they did not reduce total ATR transported in the leachate. Leachate from the orchardgrass lysimeters contained the highest proportion of ATR metabolites (64.2%). Timothy and smooth bromegrass treatments also displayed a significant increase in ATR metabolites in leachate. Grass-treated lysimeters showed higher microbial biomass carbon than bare ground. For ATR treatments, the proportion of metabolites in the leachate strongly correlated with the elevated soil microbial biomass carbon in forage treatments. In contrast, DKN degradation was poorly correlated with soil microbial biomass carbon, suggesting that DKN degradation is an abiotic process.

Atrazine↗

In situ dynamics of phosphorus in the rhizosphere solution of five species.

Root activity can modify the chemistry of the rhizosphere and alter phosphorus (P) availability and uptake. However, until recently, relatively little was known about the dynamics of soil solution P at the root surface because of our inability to measure in situ changes in solution P at the plant root. A mini-rhizotron experiment with corn (Zea mays L. cv. Stine 2250), soybean [Glycine max (L.) Merr. cv. Pioneer 3563), cottonwood (Populus deltoids L.), smooth brome (Bromus inermis Leyss.), and switchgrass (Panicum virgatum L.) was conducted to measure the spatial and temporal dynamics of P in the rhizosphere solution of a fine silty, P-rich calcareous soil (solid-phase total P concentration = 62 mg kg(-1), pH = 7.68) from western Iowa. Micro-suction cups were used to collect samples of soil solution from defined segments of the rhizosphere, and capillary electrophoresis (CE) was used to determine the P concentration of the soil solution. At the end of 10 d, a decreasing P concentration gradient in soil solution toward the root was observed in corn, cottonwood, and smooth brome. No clear rhizosphere effect was observed for soybean and switchgrass. Statistical analysis indicated significantly lower solution P concentrations in the rhizospheres of corn (p = 0.05), cottonwood (p = 0.01), and smooth brome (p = 0.01) compared with bulk soil solution. Results indicate that P depletion from rhizosphere soil solution depends on plant species. Under the conditions of this study, corn, cottonwood, and smooth brome were more effective in depleting solution P than soybean and switchgrass.

Kinetics↗

Utilization of biosolids during the phytoremediation of hydrocarbon-contaminated soil.

Addition of anaerobically digested sewage sludge (biosolids) to soil may improve conditions for phytoremediation of petroleum hydrocarbons (PHCs) through improved soil chemical, biological, and physical properties. A 32-wk greenhouse study investigated three rates of biosolids addition (0, 13.34, and 26.68 g oven-dry biosolids kg(-1) oven-dry soil) and the presence or absence of smooth brome (Bromus inermis Leyss. cv. Carlton) plants on the removal of diesel (3.5 g kg(-1) oven-dry soil) in an industrial, sandy loam soil. Diesel PHCs were divided into two fractions based on equivalent normal straight-chain boiling point ranges (F2: nC10-nC16; F3: nC16-nC34). The addition of biosolids did not increase the extent of PHC degradation but did result in significantly greater first-order decay constants compared to unamended controls. Overall, the presence of plants did not increase the rate or extent of PHC degradation, relative to that observed in unamended, non-vegetated soils. Vegetation was, however, an important factor within the biosolids-amended soils as was observed by a greater extent of PHC degradation. Some of this decrease was attributed to plant-induced removal of biosolids components that were contributing to the F3 fraction. Overall, the low-amendment rate (13.34 g oven-dry biosolids kg(-1) oven-dry soil) was considered to be the most effective treatment because it produced the greatest overall PHC degradation rate (0.226 wk(-1) for total PHCs) and resulted in the greatest recovery of biosolids-derived N by smooth brome (26.6%).

Agriculture↗

Species and Nitrogen Effect on Growth Rate, Tiller Density, and Botanical Composition in Grass Hay Production.

Numerous studies have evaluated growth, stand dynamics, and botanical composition of grass swards separately, but little information is available on the interaction of these factors. The objectives of this study were to determine the response of growth rate, tiller density, and botanical composition in orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), and timothy (Phleum pratense L.) to different N levels. Growth rates ranged from 8.6 to 1.54, 9.14 to 0.67, and 4.19 to 0.29 g dry matter (DM) m(-2) d(-1) in orchardgrass, smooth bromegrass, and timothy. Orchardgrass growth rates responded to changes in abiotic conditions, while smooth bromegrass and timothy expressed less plasticity under favorable growth environments. All species exhibited temporal fluctuations in tiller density. Orchardgrass and smooth bromegrass tiller densities were not closely associated with yield, presumably because of compensation in tiller weight. Nitrogen did not affect tiller density during the first production year, but orchardgrass tiller density was influenced by N throughout the second production year, including the fall growth period, when tiller density in all species was affected. Aggressive growth rates in orchardgrass reduced species diversity by 65% by the end of the second production year. Total diversity in smooth bromegrass decreased from 7.2 to 3.5 species 0.25 m(-2) compared with an increase in timothy from 1.5 to 5.7 species 0.25 m(-2) due to a combination of slow growth and reduced tiller density. Orchardgrass and smooth bromegrass are superior to timothy in Northeast hay production systems because of greater DM production and less weed competition.

Journal Article↗

Influence of Aspergillus oryzae fermentation extract on forage intake, site of digestion, in situ degradability, and duodenal amino acid flow in steers grazing cool-season pasture.

Ten ruminally and duodenally cannulated (326 +/- 28 kg) and four esophageally fistulated (394 +/- 23 kg) steers grazing cool-season pasture throughout the growing season were used to evaluate the influence of Aspergillus oryzae fermentation extract (AO) supplementation on intake, forage nutrient utilization, and duodenal amino acid flow. Steers grazed a predominantly smooth brome (Bromus inermis L.) pasture, and measurements were taken in three periods (June, July, and August). Steers were dosed daily at 0700 via the ruminal cannula with AO (2 g of AO per steer daily; DM basis) or not supplemented with AO. Each period consisted of 18 d for adaption to AO and 7 d for collection. Forage N was greater, and ADF was lower (P < .10), in June than in July and August. Ruminal pH, ammonia, total VFA concentration, and VFA proportions were not affected (P > .10) by AO supplementation. In vitro DM digestibility (percentage) and forage OM intake (grams/kilogram of BW) were greater (P < .10) for steers supplemented with AO. Ruminal and total tract NDF and ADF digestibilities were lower in June and greater during July (P < .10) in steers supplemented with AO. Total tract percentage of N disappearance was lesser during June and greater (P < .10) during July for steers receiving AO. Total, essential, and nonessential amino acid flows were increased (P < .10) by both AO supplementation and advancing season. In situ rate of ruminal CP degradation was not affected (P < .10) by treatment during any period.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

Influence of energy source on forage intake, digestibility, in situ forage degradation, and ruminal fermentation in beef steers fed medium-quality brome hay.

Eight ruminally cannulated steers (average initial weight 196 +/- 13 kg) were arranged in a replicated 4 x 4 Latin square. Steers had ad libitum access to chopped brome hay (Bromus inermus L. 9.9% CP) and one of four supplements. Supplements were fed to provide 195 g of CP.steer-1 x d-1 (equalized with soybean meal), and supplemental energy intake was similar among energy supplements. Supplemental treatments were control (CTRL; primarily soybean meal), barley (BAR), beet pulp (PULP), and corn (CORN). Amounts fed were 481, 1,285, 1,335, and 1,289 g of DM.steer-1 x d-1 for CTRL, BAR, PULP, and CORN, respectively. Individually stanchioned steers were allowed a 13-d adaptation period followed by an 8-d collection period. Chromic oxide was used as the indigestible flow marker. Forage intake was less (P < .10) for steers fed BAR, PULP, and CORN than for CTRL steers, but total intake (forage+supplement) did not differ among treatments. Total tract DM and OM digestibilities were greater (P < .10) for PULP- and CORN- than for CTRL- and BAR-supplemented steers. Digestibility of NDF was least (P < .10) for BAR, intermediate for CORN, and greatest for CTRL and PULP (44.0, 47.2, 50.1, and 52.1%, respectively). Apparent CP digestibility was least (P < .10) in BAR-(60.8), greatest in CTRL- (69.7), and intermediate in PULP- and CTRL- (64.0 and 64.4) supplemented steers. Ruminal DM fill was less (P < .10) in steers fed BAR and PULP than in CTRL steers. No differences (P < .10) were noted in DM and NDF rate of in situ degradation. Rate of forage CP in situ degradation was faster (P < .10) in CTRL- and PULP- than in CORN- and BAR-supplemented steers. Steers fed BAR and PULP supplements exhibited a lower overall pH response curve (P < .005) than did steers fed CTRL and CORN; this finding corresponded to increased (P < .005) response curves in PULP-fed steers for total VFA, acetate, and propionate compared with other treatments. These data indicate that energy supplementation decreased forage intake, altered ruminal fill, shifted VFA patterns, and changed in situ rate of forage CP degradation. Moreover, PULP maintained NDF digestibilities equal to CTRL levels, whereas CORN and BAR did not.

Animal Feed↗

Ruminal degradation of switchgrass, big bluestem, and smooth bromegrass leaf proteins.

Two in situ protein disappearance experiments were conducted to determine disappearance rates of leaf protein fractions and characterize individual leaf protein fractions that escaped ruminal degradation. Fresh leaf blades of two warm-season grasses, switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman), and one cool-season grass, smooth bromegrass (Bromus inermis Leyss.), were included in Exp. 1. Only warm-season grasses were used in Exp. 2. Leaves were harvested from greenhouse-grown plants, placed in polyester bags, and incubated up to 48 h in situ in three ruminally fistulated steers fed diets of warm-season grass hay. The rate of protein disappearance for switchgrass (.037 h-1) was slower (P < .10) than that for big bluestem (.110 h-1). Big bluestem and smooth bromegrass (.169 h-1) disappeared at similar rates, whereas switchgrass disappeared more slowly (P < .05) than smooth bromegrass in Exp. 1. Rates of protein disappearance in Exp. 2 were similar for switchgrass (.112 h-1) and big bluestem (.116 h-1). Major protein fractions that resisted ruminal degradation in both experiments, detected using SDS-PAGE, were at approximate molecular weights of 56, 26, and 24 kDa. For switchgrass and big bluestem, total protein and individual protein fractions were generally at higher concentrations and present for longer periods of time than for smooth bromegrass. This suggests that a mechanism may exist in C4 species that allows certain protein fractions to remain undegraded for longer periods compared with smooth bromegrass.

Animals↗

Voluntary intake, digestibility, and subsequent selection of Matua bromegrass, coastal bermudagrass, and alfalfa hays by yearling horses.

Matua bromegrass (Bromus willdenowii Kunth. cv. Grasslands Matua) was introduced in 1973, but little information exists concerning its potential as a hay for horses. Thus, voluntary intake and apparent digestibility of OM, CP, and fiber components of Matua by 18 Quarter Horse yearlings (mean initial BW 354 kg; SE 5.8) were compared with alfalfa (Medicago sativa L.) and coastal bermudagrass (Cynodon dactylon L.) as hays in a randomized block design. A 15-d adjustment period was followed by a 5-d collection period during which the hays were consumed ad libitum. Voluntary intake of DM was greater (P<.01) for alfalfa (10.9 kg/d) than for the mean of the grasses, and intake of Matua (10.0 kg/d) was greater (P<.001) than that of bermudagrass (7.4 kg/d). Apparent digestibility of OM was greater (P<.001) for alfalfa (74%) than for the mean of the grasses but did not differ between Matua (64%) and bermudagrass (60%). At the end of the digestion trial, each yearling was offered each of the three forage hays during an 11-d period to determine subsequent preference and effect of previous hay experience. Yearlings preferred alfalfa over the grass hays and generally selected more Matua than bermudagrass. All yearlings consumed less of the forage species to which they had been previously exposed compared with unadapted yearlings. The Matua hay fed in this trial was palatable and met most of the nutritional needs for yearling horses.

Animal Feed↗

Effect of fiber-based creep feed on intake, digestion, ruminal fermentation, and microbial efficiency in nursing calves.

Six Angus crossbred cow-calf pairs (653 +/- 35 kg and 157 +/- 10 kg initial BW for cows and calves, respectively) were used to evaluate the influence of a fiber-based creep feed on intake, ruminal fermentation, digestion characteristics, and microbial efficiency in nursing beef calves. Cow-calf pairs were stratified by calf age and assigned randomly to one of two treatments: control (no supplement) or supplemented. Supplemented calves received 0.9 kg of a 49% soy hulls, 44% wheat middlings, 6% molasses, and 1% limestone supplement (DM basis) daily. All calves were cannulated in the rumen and duodenum and given ad libitum access to chopped brome hay (Bromus inermus L; 7.43% CP, 40.96% ADF, and 63.99% NDF; DM basis). Supplementation was initiated on May 1 (88 +/- 10.3 d calf age). Three sampling periods were conducted throughout the study (June 14 to 25, July 5 to 16, and August 9 to 20). Supplement and forage were offered at 0800 daily. Total, hay, and milk OM intakes of nursing calves were not affected by supplementation (2,014 vs. 2,328 +/- 288.8, 1,486 vs. 1,029 +/- 3,06.9, and 528 vs. 575 +/- 87.0 g/d, respectively). Milk OM intake was less (P < 0.09) in August than in June and July (635, 691, and 345 +/- 110.6 g/d for June, July, and August, respectively). A supplementation x month interaction occurred (P < 0.10) for total-tract OM digestion. Supplementation did not affect (P > 0.40) total-tract OM digestibility during June and August; however, during July, total-tract OM digestibility was lower (P = 0.03) for the control calves. Ruminal ammonia concentration, total VFA, and butyrate molar proportion increased (P < 0.05), whereas acetate proportion decreased (P = 0.01) in supplemented calves. Microbial efficiency was not influenced by supplementation (11.8 vs. 12.0 g/kg of OM truly fermented for control and supplemented calves, respectively). These data indicate that fiber-based supplements can be used as creep feed without negative effects on OM intake, total-tract OM digestibility, and ruminal fermentation characteristics in nursing beef calves.

Animal Feed↗

Mefluidide effects on smooth brome composition and grazing cow-calf performance.

Mefluidide, a plant growth regulator, was evaluated in two cow-calf grazing trials and one herbage trial on smooth brome (Bromus inermis) pastures stocked at recommended densities in eastern Nebraska. Mefluidide-treated pasture increased cow and calf production during August of 1982 (P = .03) and calf production was greater during July of 1983 (P = .09). Mefluidide-treated smooth brome pastures increased calf production over the 1982 grazing season (P = .11) and cow gain over the 1982 (P = .12) and 1983 grazing seasons (P = .13). Mefluidide decreased neutral detergent fiber (NDF) content and increased crude protein content of smooth brome during both years (P less than .05), and increased in vitro dry matter disappearance (IVDMD) in 1982 (P less than .05). In ungrazed smooth brome, mefluidide treatment appeared to shift dry matter production to green leaves from green stem and brown leaf and stem fractions. Cell wall components [NDF, acid detergent fiber (ADF) and lignin] of green leaves were not affected significantly by mefluidide treatment, although green stems treated with mefluidide were lower in ADF and lignin (P less than .05).

Acetamides↗

Escape protein supplementation of yearling steers grazing smooth brome pastures.

Two grazing trials utilizing individually supplemented yearling steers were conducted to study the effect of supplemental escape protein on steer performance during the active growth periods, spring and fall, of smooth brome (Bromus inermis). Graded levels (0, .11, .23 and .34 kg.head-1.d-1) of an equal-protein-basis mixture of bloodmeal and corn gluten meal were offered daily, replacing corn starch, which was used as the negative control. All steers received 582 g supplemental dry matter per day. Supplementation with escape protein improved daily performance in both spring (P less than .01) and fall (P less than .02). Analysis of pooled data from both trials indicated a linear (P less than .01) and quadratic (P less than .05) increase in steer performance with increasing level of escape protein in the diet. Analysis of grass samples collected throughout and composited over each trial demonstrated that grass protein was highly degraded in the rumen. Using a modified dacron bag technique, 12-h degradability was found to be 80 to 90% of the potentially digestible protein fraction. Rates of protein degradability were 14 and 11.7%/h. Assuming 5%/h rate of passage, escape protein was calculated to be 9.2 and 13.1% of total protein. As a result of the significant growth response observed above that of the energy-supplemented controls and the high ruminal protein degradabilities of the grass observed in the laboratory, it was concluded that growing ruminants grazing actively growing smooth brome pastures were deficient in metabolizable protein.

Animal Feed↗

Copper status of muskoxen: a comparison of wild and captive populations.

We compared wild muskoxen (Ovibos moschatus) on Banks Island (Northwest Territories, Canada) with captive animals maintained on grass (Bromus sp.) hay and supplemental minerals. We measured copper (Cu) in liver, whole serum, and deproteinated serum (unbound Cu) as well as serum activity of the Cu-enzyme ceruloplasmin. Unbound serum Cu concentrations did not change with season in captive animals (n = 53). Ceruloplasmin activity was similar between seasons in females but elevated in males during breeding in autumn. Increasing concentrations of Cu in whole sera were mainly associated with protein whereas unbound Cu predominated at low concentrations of whole serum Cu. Ceruloplasmin activity and serum Cu concentration were linearly related to liver Cu in female muskoxen. Measures of copper status in females were lower in the wild (n = 19) than in captivity (n = 16): 8 vs. 160 ug Cu.g-1 of whole liver; 0.67 vs. 1.15 microgram unbound Cu.ml-1 whole serum and; 22 vs. 33 IU.l-1 ceruloplasmin activity. Bioavailability of Cu may limit the population on Banks Island especially when density of animals is high. The wide range of hepatic Cu concentrations in muskoxen indicated accumulation of Cu without apparent ill effect in captive animals. Hepatic storage of Cu may allow wild muskoxen to contend with low and fluctuating availability of Cu in small foraging areas at high latitudes.

Animals↗

Seedling Development and Field Performance of Prairiegrass, Grazing Bromegrass, and Orchardgrass.

Seedling establishment is a critical phase in pasture management. Knowledge of the seedling development of new forages is necessary to develop management practices and recommend species mixtures for pasture seedings. We compared seedling growth and development of prairiegrass (Bromus willdenowii Kunth = B. catharticus Vahl), grazing bromegrass (B. stamineus Desv.), and orchardgrass (Dactylis glomerata L.) in controlled environment and field studies. Seedlings were sampled weekly for 7 wk in the growth chamber and greenhouse beginning 8 to 10 d after planting (DAP). The number and mass of leaves and roots were recorded. In the field, leaf development was measured during spring and fall of 1997, and leaf and root development were measured during spring and fall of 1999. Forage dry matter (DM) yield was measured in clipped field plots during 1998 to 2000. Grazing bromegrass had more leaves, about twice the number of tillers per seedling, and a greater seedling mass than other grasses. Grazing bromegrass also had 50 to 100% more tillers m(-2) than other grasses in clipped field plots. The larger seedling size and greater tiller density, however, did not translate into greater yield in clipped plots. Grazing bromegrass yielded 10 to 15% less than orchardgrass or prairiegrass. Because of their large seedlings and rapid development, prairiegrass and grazing bromegrass probably should be used at a lower seeding rate or perhaps not used in seed mixtures with small-seeded grasses. Seedlings of these grasses should be fully established by 40 to 50 DAP under favorable moisture and temperatures in the spring and late summer.

Journal Article↗

Floristic and agronomic aspects of cereal weeds in the Constantine high plains.

Three hundred fifty nine fields of cereals were surveyed by stratified sampling in the Constantine high plains (north-east, Algeria). In total 254 species belonging to 34 plant families were recorded. The results indicated that five families the Asteraceae, Fabaceae, Poaceae, Brassicaceae and Apiaceae were prevalent and accounted for 55% of the species. Annuals (70%), broad leaved (87%) and the mediterranean floristic element (63%) were predominant and characterized the weed flora. The agronomic study permitted to distinguish 34 important species. This harmful flora was characterized by the prevalence of annual and broad leaved weeds. Although number of grasses was low were some abundant and frequent e.g. Avena sterilis L. and Bromus rigidus Roth.. Perennial species were represented by several weeds, the most frequent and abundant were Bunium incrassatum (Boiss.) B.T., Carduncellus pinnatus (Desf.) DC. and Convolvulus arvensis L..

Algeria↗

[The frequency of pollen allergy at the population of Sarajevo region during the 2002 year].

The frequency of pollen alergy in the sample of population of Sarajevo region during the 2002 year has been investigated. The age and gender population has been different. For determination of allergy has been use of standard test carryed out in the respective laboratories of Clinical center of University of Sarajevo. The testing has been on the pollen of weed plant species and grass (graminejae) pollen. In the mixture of pollen weed plant species have been following plants: Plantago lanceolata L., Chenopodium album L., Solidago gigantea L., Artemisia vulgaris L. and Urtica dioica. 589 have been tested patients by mixture of pollen mentioned plant species and found 115 as a sensitive on pollen alergy; 65 male and 50 females. Even 61 are children to 14 years, or 53% of total sick patients. The origin of grass pollen is no determined by taxonimicly, but on the base of phenophase of grasses from this area it is possible determine potential allergenic species: Dactylis glomerata, Cynosusrus cristatus, Alopecurus pratensis, Phleum pratnse, vrstama rodova Bromus, Hordeum, Festuca and Poa. 116 pateints have been identified as sensitive on pollen alergy; 49 male and 65 females. The highest proportion of sick people have been in correlation with pollination of allergenic plants in this area.

Adolescent↗

Cantharidin decreases in vitro digestion of alfalfa and smooth bromegrass.

Blister beetles (Coleoptera:Meloidae) containing the toxin cantharidin can be incorporated with alfalfa (Medicago sativa L) during forage conservation. Cantharidin inadvertently ingested with animal feed may cause illness or death. Little information is available on the effects of cantharidin on ruminant microbial digestion. The objective of our study was to determine cantharidin effects on digestibility of alfalfa and smooth bromegrass (Bromus inermis Leyss) by measuring in vitro digestible dry matter (IVDDM) and cell wall digestion (CWD). Alfalfa dry matter digestibility, measured after IVDDM at 48 and 96 h fermentation periods, decreased as cantharidin concentration increased. Increasing cantharidin concentration also significantly reduced IVDDM of smooth bromegrass at 24 and 96 h digestion time. The CWD of alfalfa and smooth bromegrass decreased as cantharidin concentration increased. These results indicate that ingestion of cantharidin by ruminants may decrease microbial digestion of fibrous feeds and therefore may decrease the efficiency of feed utilization by ruminants.

Animals↗

[Characterization of areas at parasitic risk for sheep reared under conditions of uncontrolled breeding on the ranges of the Causses. 1. Study methodology and its application to gastrointestinal strongyles].

A flock of 50 Lacaune ewes grazed three paddocks (approximately 17ha each) in rotation. Thirteen areas were defined in each of the two selected paddocks on the account of vegetation and spatial utilization by the ewes. These areas represented one tenth of the total area of the paddock. For each area the following measures were estimated: species of grasses, bushes, grass disponibility, amount of faeces deposited, infective larval population of strongyles, duration of the utilization by the ewes for resting or grazing. The measures were achieved during two rotational cycles from May to July 1981. Among the several methods utilized for the assessment of the various parameters influencing the probable infection of animals, one was unsatisfying (estimation of grass intake) and another was of particular good value (estimation of the amount of faeces deposited by an index method). The areas at risk were characterized by a vegetation with Bromus erectus associated either with Festuca duriuscula or Brachypodium pinnatum. The infectivity of each area (number of larvae X duration of grazing) was correlated to the number of strongyle eggs deposited, the amount of faeces accumulated and to an index of pasture quality (pastoral value X biomass of available grass). This work demonstrates that in heterogeneous pasture, even if the level of parasitism (Ostertagia sp. and Nematodirus sp.) is low, area at risk could be determined.

Animal Husbandry↗