Dalea Research Articles

Native Forb Response to Aminocyclopyrachlor

AbstractNative forbs are an essential component in the functioning and diversity of prairie communities. Aminocyclopyrachlor (AMCP) will effectively control many noxious weeds that invade prairie communities; however, its efficacy on desirable broadleaf plants is relatively unknown. Few field studies have been reported, and locating adequate populations of native forbs for evaluation of tolerance to herbicides is difficult. The susceptibility of 10 prairie forb species to AMCP was evaluated in the greenhouse. Species were chosen to correlate with a field study of AMCP and a previous greenhouse experiment. AMCP was applied at 0, 35, 70, and 105 g ha−1 with a methylated seed oil (MSO) plus silicone-based non-ionic surfactant (NIS) blend at 0.25% v/v when plants reached the growth stage simulating a spring treatment for weed control. Blueflag iris (Iris versicolor L.) and harebell (Campanula rotundifolia L.) were relatively tolerant and would likely be unharmed following an application of AMCP in the field. Wild licorice (Glycyrrhiza lepidota Pursh), prairie wild rose (Rosa arkansana Porter), purple prairie clover (Dalea purpurea Vent.), and wild bergamot (Monarda fistulosa L.) were moderately susceptible to AMCP; however, plants might regrow in the field, since some survived at the highest AMCP application rate (105 g ha−1) evaluated. Skyblue aster [Symphyotrichum oolentangiense (Riddell) G. L. Nesom], Canada goldenrod (Solidago canadensis L.), blue cardinal-flower (Lobelia siphilitica L.), and blacksamson echinacea (Echinacea angustifolia DC.) were susceptible to AMCP even when applied at 35 g ha−1. The susceptibility of greenhouse-grown forbs to AMCP was the same or similar to species evaluated in the field and can be used to predict native forb tolerance in the field.

Condensed Tannins Affect Bacterial and Fungal Microbiomes and Mycotoxin Production during Ensiling and upon Aerobic Exposure.

Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g/kg dry matter (DM) of condensed tannin (CT) was ensiled without (control) or with polyethylene glycol (PEG) for 76 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics were determined, and the composition of bacterial and fungal communities were assessed using metagenomic sequencing. The addition of polyethylene glycol (PEG) that deactivated CT at ensiling increased (P < 0.05 to ∼0.001) soluble N, nonprotein N, lactic acid, total volatile fatty acids, ammonia N, deoxynivalenol (DON), and ochratoxin A (OTA) but decreased (P < 0.001) pH and water-soluble carbohydrates. The concentrations of DON and OTA increased (P < 0.001) for both silages, with the extent of increase being greater for control than for PEG-treated silage during aerobic exposure. The PEG-treated silage exhibited higher (P < 0.01 to ∼0.001) copy numbers of total bacteria, Lactobacillus, yeasts, and fungi than the control. The addition of PEG decreased (P < 0.01) bacterial diversity during both ensiling and aerobic exposure, whereas it increased (P < 0.05) fungal diversity during aerobic exposure. The addition of PEG at ensiling increased (P < 0.05) the abundances of Lactobacillus and Pediococcus species but decreased (P < 0.01) the abundances of Lactococcus and Leuconostoc species. Filamentous fungi were found in the microbiome at ensiling and after aerobic exposure, whereas Bacillus spp. were the dominate bacteria after aerobic exposure. In conclusion, CT decreased protein degradation and improved the aerobic stability of silage. These desirable outcomes likely reflect the ability of PPC CT to inhibit those microorganisms involved in lowering silage quality and in the production of mycotoxins.IMPORTANCE The present study reports the effects of condensed tannins on the complex microbial communities involved in ensiling and aerobic exposure of purple prairie clover. This study documents the ability of condensed tannins to lower mycotoxin production and the associated microbiome. Taxonomic bacterial community profiles were dominated by Lactobacillales after fermentation, with a notable increase in Bacillus spp. as a result of aerobic exposure. It is interesting to observe that condensed tannins decreased bacterial diversity during both ensiling and aerobic exposure but increased fungal diversity during aerobic exposure only. The present study indicates that the effects of condensed tannins on microbial communities lead to reduced lactic acid and total volatile fatty acid production, proteolysis, and mycotoxin concentration in the terminal silage and improved aerobic stability. Condensed tannins could be used as an additive to control unfavorable microbial development and maybe enhanced feed safety.

Filíocht Nua: New Poetry

Filíocht Nua:New Poetry Noel Monahan child and lamb I found an early lamb in Tully's fieldCaught in a briary ditch and I rescued him,Carried him home bouncing and bleating.A robin in the bushes took note, the other sheep stared.Back in the kitchen I tied his feet with twine,Placed him in a cardboard box before the cooker.My mother loved him. She was going on aboutHis loaf white fleece, his angel eyes . . . but he doesn't belong here. You stole a lamb from our neighbours, my father said.Because my father was the greatest man then,I agreed to return the lamb the next morning.Sadly, I watched him drift away with his motherThrough a gap into the next field. Then I turned awayTo think of something else to do that day. [End Page 57] where the wind sleeps Something will come to you in your dreams thatWill help you find your way in abandoned places.Here the wind sleeps with nettles and briarsIn half-empty walls and the owl hatchesHer chicks in the belfry. Here an apparitionOf monks in off-white habits sleepwalkHolding empty skulls in their hands and listeningTo the slow noise of old ways dying.Each in his solitude finds dereliction,Prayer that does not rest on words but livesIn darkness and out of the depths of nightHeaven falls like snow on a linen altar,Two candles burn, carnations as white asChildren's teeth are little nails of glory and grief. [End Page 58] aphrodite in the snow I awaken to the surprise of seeing youStretched naked outside my window,Your ivy hair full of snowflakes,Earrings of frozen ice, blizzard of pearl powderFor your face. Fresh snow begins to blowAcross your navel, curves about your pubic bones,Lodges between your thighs. I know you drifted here.The wind shaped your limbs, your snow white girdleAnd now the wind of forty voices sings:Spem In Alium in the snow,Choral whispers of hope in the singing bowl of winter.A car passes with head-lights on, someone is scraping a drivewayAnd I'm not sure whether I'm looking at the evening or morning star. [End Page 59] famine times A stooped croneLeans on a stick,Her face a famine, withered breasts,Foul breath, sunken eyes. She kisses the clayThe hunger-worm wrigglesFrom drill to furrow,Blight clouds gather. She knows what little remains,Begs God for favours,Prayer makes her tired, [End Page 60] prairie mother She continues to survive out here in the Midwest,Sheltering in the cornstalks of the prairies.Unknowingly, her heart throbs within usTo remind us of who she once was and whereShe is going. She hides in tangled rootsWhen fire strikes. She's the rain afterThe long dry spell, the coneflowers,The purple prairie clover . . . She's a tree-houseTo draw us back to childhood, a prairie windTo brush the old man's whiskers,By night she sleeps with the bees and starsIn the honey hive moon. She's a memoryThat lives in our forgetfulness.Clay holds her soul. [End Page 61] god man We buried our deadPerformed rituals.The gods worried usAs much as they cheered us. When the gods needed food We fed them our children. When the gods needed shelter We built stone circles, temples . . .Later on, we abandoned the caves,Dropped our flint knives and spears on the floorDaubed and wattled our homesSettled for a plough,Bred black headed cattle,White cows with bracelets, necklaces . . . We complained about all the work, Argued and fought, Small-talked about a girl, Found face down in a bog.Many blamed the old gods.Time on our handsWe turned our backs on themAnd found a New One. [End Page 62] pull down the house Break down the doors and windowsLet the jackdaws fly out from the chimneys,The mice leave their nestsUnder the floorboards. Tear the wallpaperIn the bedrooms, pluck the weeds from the gutters,Knock all...

Fecal microbiota of lambs fed purple prairie clover (Dalea purpurea Vent.) and alfalfa (Medicago sativa).

The present study assessed the effect of purple prairie clover (PPC) and PPC condensed tannins (CT) on the fecal microbiota of lambs using high-throughput 16S rRNA gene pyrosequencing. A total of 18 individual lambs were randomly divided into three groups and fed either green chop alfalfa (Alf), a 40:60 (DM basis; Mix) mixture of Alf and PPC, or Mix supplemented with polyethylene glycol (Mix-P) for 18days. Fecal samples were collected on days 13 through 18 using digital rectal retrieval. The DNA of fecal samples was extracted and the microbial 16S rRNA gene amplicons were sequenced using 454 pyrosequencing. Regardless of diet, the bacterial community was dominated by Firmicutes and Bacteroidetes with many sequences unclassified at the genus level. Forage type and CT had no effect on the fecal microbial composition at the phylum level or on α-diversity. Compared to the Alf diet, the Mix diet reduced the relative abundance of Akkermansia (P=0.03) and Asteroleplasma (P=0.05). Fecal microbial populations in Alf and Mix-P clustered separately from each other when assessed using unweighted UniFrac (P<0.05). These results indicate that PPC CT up to 36g/kg DM in the diet had no major effect on fecal microbial flora at the phyla level and exerted only minor effects on the genera composition of fecal microbiota in lambs.

Apparent Seed Digestibility and Germination of Seeds After Passage Through the Digestive System of Northern Bobwhite (Colinus virginianus)

Limited information is available regarding the digestibility or germination of seeds after passage through the digestive system of northern bobwhites (Colinus virginianus), especially of plants associated with the sand sagebrush (Artemisia filifolia)–mixed prairie community. Thus, our objectives were to determine the apparent digestibility of seeds of 45 plant species associated with the sand sagebrush–mixed prairie community and the germination of seeds before and after passage through the digestion system of bobwhites. Seeds of 12 of 45 species fed to bobwhites were found to pass through the digestive system intact. The apparent seed digestion pattern of the 12 plant species with incomplete digestion of seeds was legumes > forbs > grasses > shrubs. At the end of a 7-d germination period, the digestion of seeds by bobwhites reduced seed germination of alkali sacaton (Sporobolus airoides), black-eyed Susan (Rudbeckia hirta), and western yarrow (Achillea millefolium var. occidentalis) but increased the germination of white prairie clover (Dalea candida) seeds (P ≤ 0.05). However, the germination percentage of predigestion seeds of white prairie clover exceeded that of postdigestion seeds (P < 0.05) by the end of a 21-d germination period. Averaged across species, the 21-d seed germination of postdigestion seeds was lower than predigestion seeds (P < 0.05). Viable seeds found in feces are disseminated by quail onto the landscape. Plant species that have been lost from overgrazing or the application of herbicides might be reintroduced onto landscapes through dissemination by bobwhites via food plots, feeding stations, or both if the seeds are deposited onto a suitable germination substrate with suitable seed germination conditions.

286 Structural composition and protein precipitation capacity of condensed tannins from purple prairie clover (Dalea purpurea Vent.)

286 Structural composition and protein precipitation capacity of condensed tannins from purple prairie clover (Dalea purpurea Vent.)

284 Characterization of condensed tannins from freeze-dried, silage, or hay purple prairie clover (Dalea purpurea Vent.): Structure composition, protein precipitation, and anti-Escherichia coli properties

284 Characterization of condensed tannins from freeze-dried, silage, or hay purple prairie clover (Dalea purpurea Vent.): Structure composition, protein precipitation, and anti-Escherichia coli properties

616 Effect of conservation method on in vitro ruminal fermentation of purple prairie clover (Dalea purpurea Vent.) in batch culture

616 Effect of conservation method on in vitro ruminal fermentation of purple prairie clover (Dalea purpurea Vent.) in batch culture

283 Effects of condensed tannins on bacterial and fungal core microbiomes involved in the ensiling and aerobic spoilage of purple prairie clover (Dalea purpurea Vent.) silage

283 Effects of condensed tannins on bacterial and fungal core microbiomes involved in the ensiling and aerobic spoilage of purple prairie clover (Dalea purpurea Vent.) silage

Effect of purple prairie clover (Dalea purpurea Vent.) hay and its condensed tannins on growth performance, wool growth, nutrient digestibility, blood metabolites and ruminal fermentation in lambs fed total mixed rations

This study evaluated the effects of purple prairie clover (PPC, Dalea purpurea Vent.) hay and its condensed tannins (CT) on feed intake, growth performance, wool growth, nutrient digestibility, blood metabolites and rumen fermentation in lambs fed diets containing PPC and alfalfa hay. Alfalfa and PPC were harvested at similar growth stage, sun-cured to <12% moisture, and stored in a shed for 120 d. Thirty six individually fed lambs were randomly allocated into three groups and fed total mixed ration containing 40% (dry matter (DM) basis) of a pelleted barley grain based concentrate and 60% of alfalfa hay (AH), or 60% PPC hay (PH) or PH supplemented with polyethylene glycol (PH-p) for 77 d. Lambs were fed once daily and weighed bi-weekly. Faeces samples were collected in the 5th wk for 5 d to determine nutrients digestibility using acid insoluble ash as a marker. Lambs were slaughtered at the end of experiment to evaluate the carcass characteristics. Wool yield and quality were measured using a 10cm dye band applied on d 0 and harvested on d 75. Blood samples were collected to analyze serum metabolites and antioxidant enzymes, and rumen fluid was sampled to analyze rumen fermentation products. Lambs fed PH had lower (P<0.01) DM intake than AH or PH-p. Growth performance, wool growth parameters and carcass characteristics did not differ among diets. Lambs fed PH-p had greater (P<0.05–0.001) DM, organic matter (OM), crude protein (CP), neutral detergent fibre (aNDF) and acid detergent fibre (ADF) digestibility than those fed AH, and greater (P<0.05–0.001) CP, aNDF and ADF digestibility than those fed PH diet. Lambs fed PH exhibited greater apparent total tract digestibility of DM (P<0.05) and OM (P<0.05) and tended (P=0.059) to have greater CP digestibility compared to those fed AH. Lambs consuming PH diet had lower (P<0.05) blood urea nitrogen and creatinine than AH and lower (P<0.05) blood glucose and urea than PH-p, but greater (P<0.01) total antioxidant capacity and catalase activity than AH diet. Lambs fed PPC CT had lower (P<0.05) concentrations of ammonia, total VFA, propionate, iso-butyrate, iso-valerate and protozoa. It was concluded that PPC hay had greater nutritive value to alfalfa hay owing to its greater DM, OM and protein digestibility, but did not improve lamb growth.

1565 Effect of purple prairie clover (Dalea purpurea Vent.) and its condensed tannins on nutrient intake, digestibility, and growth performance of lambs

1565 Effect of purple prairie clover (Dalea purpurea Vent.) and its condensed tannins on nutrient intake, digestibility, and growth performance of lambs

1564 Effects of condensed tannins on the ensiling and aerobic stability of purple prairie clover (Dalea purpurea Vent.) silage

1564 Effects of condensed tannins on the ensiling and aerobic stability of purple prairie clover (Dalea purpurea Vent.) silage

Effects of conservation method on condensed tannin content, ruminal degradation, and in vitro intestinal digestion of purple prairie clover (Dalea purpureaVent.)

In situ and in vitro experiments were conducted to evaluate the effect of forage conservation method on the chemical composition, ruminal degradation, and intestinal digestion of purple prairie clover (PPC), which was conserved as freeze-dried forage (FD), silage (SIL), or hay (Hay). In situ dry matter (DM), neutral detergent fiber (NDF), and crude protein (CP) degradabilities were determined by incubating the forages in three rumen-cannulated heifers for 0, 1, 2, 4, 8, 24, 48, and 72 h. Intestinal DM and CP digestions were estimated by incubating 12 h ruminal in situ residues in a modified three-step in vitro procedure. Ensiling decreased (P &lt; 0.001) extractable condensed tannins (CT) but increased (P &lt; 0.001) protein- and fiber-bound CT compared with FD and Hay. The ruminal disappearance of CP at 8 and 24 h was affected by conservation method (P &lt; 0.001), ranked as SIL &gt; FD &gt; Hay. The effective degradability of DM was lower (P &lt; 0.001) for Hay than for FD and SIL. Ensiling lowered (P &lt; 0.001) whereas haymaking increased (P &lt; 0.001) intestinal digestion of CP compared with the fresh PPC. There were no differences in intestinal DM digestion among the three conserved forages. The results suggest that PPC conserved as Hay may conserve the biological activity of CT via preserving extractable CT more than as SIL, thus having the potential to improve protein utilization in ruminants.

A new species of Dalea (Fabaceae, Faboideae) from Jalisco, México

In this paper we describe and illustrate Dalea jaliscana as a new species from Jalisco, Mexico, morphologically related to Dalea sericea.

Seed Dormancy Mechanisms in Basalt Milkvetch and Western Prairie Clover

A greater diversity of native legumes and forbs is desirable for rangeland restoration practice in the Intermountain Region of the western United States. But for such diversity to materialize in the seed marketplace and to be effective in restoration practice, seeds that germinate reliably in seed fields and on restoration sites are needed. We measured germination response of two native legumes, basalt milkvetch (Astragalus filipes Torr. ex A. Gray) and western prairie clover (Dalea ornata [Douglas] Eaton & Wright), after eight germination treatments. Treatments were a factorial combination of 1) seed scarification with sandpaper (or unscarified), 2) a substrate of moist sand (or blotter paper), and 3) a 3-wk prechill at 5° (or nonprechilled). Cumulative germination increased linearly throughout the 10-wk course of the experiment for all treatment combinations in both species. Scarification increased germination of western prairie clover, but prechilling and substrate had no effect. In contrast, prechilling, scarification, and a sand substrate all increased germination of basalt milkvetch. Hence, for this species the prechilled/scarified/sand treatment combination displayed the numerically highest germination for all 10 wk (30−43%), and the nonprechilled/unscarified/blotter paper treatment combination always germinated lowest (1−3%). Results were consistent with physical dormancy (hard-seededness) limiting germination of western prairie clover and combinational dormancy (i.e., co-occurrence of physical and physiological dormancy) limiting germination of basalt milkvetch. Of the two species, we have found basalt milkvetch to be the more difficult to establish from seed. By prechilling acid-scarified seed in moist sand, basalt milkvetch was successfully established in two field trials seeded in mid-April. Nonprechilled mechanically (sandpaper) scarified seed germinated as high as prechilled acid-scarified seed. By scarifying and prechilling basalt milkvetch seed to address physical and physiological dormancy mechanisms, respectively, this seed-treatment protocol may be “scaled up” to produce large quantities of germinable seed.

The effects of temperature and scarification on seed germination of three Dalea species

Schellenberg, M. P. and Biligetu, B. 2015. The effects of temperature and scarification on seed germination of three Dalea species. Can. J. Plant Sci. 95: 1117–1120. Ecological varieties of North American native plants are used for reclamation or rangeland seeding in Canada. The objectives of the study were to determine the optimum temperature for seed germination and to evaluate the effect of seed scarification on germination of ecological varieties of purple prairie clover [Dalea purpureum (Vent) Rydb.], white prairie clover [Dalea candida (Michx.) Willd.], and a wild collection of hairy prairie clover [Dalea villosa (Nutt.) Spreng var. villosa]. Germination was studied in growth chambers with constant temperatures of 5, 10, 20, and 30°C for 28 d using a randomized complete block design (RCBD). An additional germination experiment was conducted at 20°C after seed scarification. Based on days to initiate first germination and final germination, the optimum temperature for germination was 20°C for the three species. Final germination was the highest for purple prairie clover (51%), intermediate for white prairie clover (27%), and lowest for hairy prairie clover (5%). Seed scarification increased final germination by around 20% for all three species.

Germination and Seedling Emergence of Three Semiarid Western North American Legumes

Few seed sources of North American forbs are available for revegetation/restoration of degraded western rangelands adapted to annual precipitation zones less than 300 mm, and those that are available are mainly wildland collected. The amount of time and resources necessary to make wildland collections in quantity results in high seed prices and variable seed quality, such that forbs have been under-represented in rangeland seeding mixes. We have previously identified western prairie clover (Dalea ornata Douglas ex Hook.), Searls’ prairie clover (Dalea searlsiae A. Gray), and basalt milkvetch (Astragalus filipes Torr. ex A. Gray) as native species adapted to low precipitation zones in the western United States for which field-grown seed production would potentially reduce seed costs and increase availability. A series of glasshouse experiments were conducted to determine the effects of scarification, planting depth, and soil composition on germination and seedling emergence of these species. All three species produce hard seeds, and scarification was necessary to increase germination and seedling emergence. Compared with a 6-mm planting depth, a planting depth of 19 mm retarded the rate of emergence for all species but only reduced the total seedling emergence for basalt milkvetch. With seed scarification in sandy soils, prairie clover seedling emergence exceeded 80% while basalt milkvetch was less than 10%. With seed scarification in soils with higher clay content, prairie clover total seedling emergence reduced to 58–70% while basalt milkvetch increased to approximately 30%. Along with enhancing stand establishment in seed production fields, these data will assist land managers in planning for optimal establishment of these species in rangeland revegetation/restoration projects.

Purple Prairie Clover (Dalea purpurea Vent) Reduces Fecal Shedding of Escherichia coli in Pastured Cattle

A 3-year (2009 to 2011) grazing study was conducted to assess the effects of purple prairie clover (PPC; Dalea purpurea Vent) on fecal shedding of total Escherichia coli in cattle. Three pasture types were used in the experiment: bromegrass (Check), mixed cool season grasses with PPC (Simple), and mixed cool and warm grasses with PPC (Complex). Pastures were rotationally grazed during a summer and fall grazing period. PPC was grazed in summer at the vegetative or early flower stage and at the flower or early seed stage during the fall. Fecal samples were collected for enumeration of E. coli and chemical analyses. Forage samples were collected throughout grazing for analysis. Condensed tannins (CT) were only detected in Simple and Complex pastures that contained PPC, with higher concentrations found in the fall than in the summer. Fecal counts of E. coli in cattle grazing Simple and Complex pastures linearly decreased (P < 0.05) over summer to fall in all 3 years, an outcome not observed in cattle grazing the Check pasture. Across the three grazing seasons, fecal E. coli was lower (P < 0.05) in cattle grazing Simple and Complex pastures than in those grazing the Check pasture during the fall. During the fall, feces collected from cattle grazing the Check pasture had higher (P < 0.05) values for pH, N, NH3-N, total volatile fatty acids, and branched-chain volatile fatty acids, but a lower (P < 0.05) acetate:propionate ratio than feces collected from cattle grazing Simple or Complex pastures. In a second experiment, two strains of E. coli were cultured in M9 medium containing 25 to 200 μg/ml of PPC CT. Growth of E. coli was linearly (P < 0.01) reduced by increasing levels of PPC CT. Scanning electron micrographs showed electron-dense filamentous material associated with the outer membrane of E. coli cells exposed to CT. Incorporation of PPC into forage reduced the fecal shedding of E. coli from grazing cattle, likely due to the anti-E. coli properties of PPC CT.

Effects of purple prairie clover (Dalea purpurea Vent.) on feed intake, nutrient digestibility and faecal shedding of Escherichia coli O157:H7 in lambs

This study was conducted to assess the effects of purple prairie clover (PPC, Dalea purpurea Vent.) on feed intake, nutrient digestibility, faecal shedding of Escherichia coli O157:H7 and blood metabolites of lambs. A total of 18 lambs were divided into three groups and housed in individual pens and fed green chop (1) alfalfa (Alf), (2) a mixture of Alf and PPC in a ratio of 40:60 (DM basis; Mix) and (3) Mix supplemented with polyethylene glycol (Mix-P) for 45 d. A 333 g/L polyethylene glycol (PEG) solution applied at the rate of 250 mL/kg DM of Mix diet was included in the third treatment to neutralize the biological activity of condensed tannins (CT) in PPC. Total tract digestibility of the diets was determined using acid-insoluble ash (AIA) as an indigestible marker. Blood samples were collected to measure serum metabolites and to estimate the activity of antioxidant enzymes. All lambs were orally inoculated with a five strain mixture of E. coli O157:H7 after determination of diet digestibility and faecal samples were enumerated for E. coli O157:H7 after 1, 2, 3, 4, 7, 14, 21 and 28 d of inoculation. Feed intake did not differ among lambs fed the three diets. Organic matter digestibility (P < 0.05) and protein digestibility (P < 0.01) of Mix were lower than that of Alf. However, the three diets had similar neutral detergent fibre digestibility. Lambs fed Mix had lower levels (P < 0.05) of serum creatinine and urea nitrogen than Alf, but both Mix and Mix-P had higher (P < 0.05) levels of serum phosphorus. Mix fed lambs had greater (P < 0.05) serum total antioxidant capacity but lower (P < 0.05) serum superoxide dismutase activity than lambs fed Alf. After inoculation, lambs fed Mix shed less E. coli O157:H7 than lambs fed Alf between d 1 and d 7 (P < 0.05–0.006), and lambs fed Mix-P between d 1 and d 3 (P < 0.05–0.012). Lambs fed Alf shed more E. coli O157:H7 than lambs fed Mix (P < 0.001) or Mix-P (P < 0.01) over the 28-d post-challenge period. Incoportaion of PPC in lamb diets at 60% of DM reduced faecal shedding in lambs challenged with E. coli O157:H7 as compared to Alf. The fact that shedding of E. coli O157:H7 was also reduced with Mix-P suggests that the anti-E. coli O157:H7 response of PPC is not solely due to CT.

Condensed tannins concentration of selected prairie legume forages as affected by phenological stages during two consecutive growth seasons in western Canada

Li, Y., Iwaasa, A. D., Wang, Y., Jin, L., Han, G. and Zhao, M. 2014. Condensed tannins concentration of selected prairie legume forages as affected by phenological stages during two consecutive growth seasons in western Canada. Can. J. Plant Sci. 94: 817–826. Studies have shown that condensed tannins (CT) at appropriate concentrations improve nutrient digestion in animals and influence ecosystem processes. However, knowledge of CT concentration in different phenological stages and different plant parts of non-conventional legumes growing in the western Canadian prairies is lacking for feed and grazing management. The research objectives were to determine the level and distribution of total CT (TCT), extractable CT (ECT) and protein-bound (PCT) or fiber-bound CT (FCT) concentrations in the whole plant of legume forages at different phenological (vegetative, flowering, seed maturity) stages and plant parts (leaves, stems, inflorescences and inflorescences+seedpods) using the Butanol-HCl procedure. Whole plant samples of purple prairie clover (Dalea purpurea Vent.), white prairie clover (D. candida Michx. ex Willd), sainfoin (Onobrychis viciifolia Scop.) and Canadian milkvetch (Astragalus canadensis L.) were collected in the 2011 and 2012 growing seasons from replicated small trial plots at vegetative, flowering and seed maturity stages. Species, phenological stages and their interactions all significantly affect the TCT, ECT, PCT and FCT concentrations in whole plant and plant parts (P&lt;0.001). Concentrations of ECT and TCT increased for all species as they matured from vegetative to seed maturity, except for sainfoin where the vegetative stage had the highest ECT and TCT levels. The highest mean ECT and TCT concentrations for purple prairie clover and white prairie clover were found in the inflorescences part at flowering stage, while sainfoin had the highest ECT and TCT concentrations in the leaves at vegetative stage. There was little variation for PCT among different phenological stages in whole plant for species except for purple prairie clover and white prairie clover which had higher (P&lt;0.05) PCT at seed maturity than at flowering stage. Only trace amounts of FCT were detected from either whole plant or different fractions of all plant species, except Canadian milkvetch. Condensed tannins were not observed in Canadian milkvetch except for trace amounts in the seed coat at seed maturity stage. The results demonstrate that legumes differ in their condensed tannin content which could potentially be used in pasture management.