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1.
In silvopastoral (SP) systems, forage responses depend on the microenvironment in which the plants develop. Our objective was to evaluate canopy and tillering characteristics of shaded 'Marandu' palisadegrass [Brachiaria brizantha (Hochst A Rich) Stapf, syn. Urochloa brizantha] under continuous stocking in a SP system. Treatments were one full sun (FS) and three shaded systems (silvopasture, SP) corresponding to distances from tree groves: 7.5 m north (SP1), and 15 m (SP2) and 7.5 m south (SP3) studied during two rainy seasons (Year 1 and Year 2). The tree in the SP system was Eucalyptus urograndis (hybrid of Eucalyptus grandis W. Hill ex Maiden × Eucalyptus urophylla S. T. Blake). The photosynthetic active radiation was greater in FS (923 μmol m-2 s-1), followed by SP2 (811 μmol m-2 s-1), SP1 (727 μmol m-2 s-1) and SP3 (673 μmol m-2 s-1). Forage accumulation in FS was 15% greater than the mean of SP1, SP2 and SP3 (10,663 kg DM/ha). There was no difference in net accumulation of leaf, stem and dead material, averaging 3,302, 3,420 and 4,063 kg DM/ha respectively. Leaf accumulation and accumulation rate were greater in Year 2, and leaf accumulation rate was similar among treatments (19 kg DM ha−1 day−1). Leaf proportion increased 14% from Year 1 to Year 2. Specific leaf area was greater for treatments SP1 and SP3 (193 cm2/g). Tiller population density was similar across treatments in Year 1. Shaded palisadegrass maintains leaf productivity similar to FS under continuous stocking in an SP system.  相似文献   

2.
A two-year experiment assessed herbage production and above- and below-ground characteristics of a highly productive monoculture (‘BRS Zuri’ guineagrass [Panicum maximum Jacq.]) and two mixtures of three grasses (Mixture 1: ‘BRS Zuri’ guineagrass, ‘BRS Xaraés’ palisadegrass [Brachiaria brizantha Stapf.], and ‘Basilisk’ signalgrass [Brachiaria decumbens Stapf.]; Mixture 2: ‘BRS Quênia’ guineagrass [Panicum maximum Jacq.], ‘Marandu’ palisadegrass [Brachiaria brizantha Stapf.], and ‘BRS Paiaguás’ palisadegrass [Brachiaria brizantha Stapf.]), cultivated in the Brazilian tropical savanna. Mixtures 1 and 2 were subjected to two grazing intensities (removal of 40 or 60% of pre-grazing height) and ‘BRS Zuri’ guineagrass monoculture was defoliated to a single grazing intensity of 50%. Treatments were randomly assigned to fifteen 0.25-ha plots and managed under intermittent stocking by cattle. Herbage accumulation rate was similar among pastures and years (p > .1). The root mass in the tussocks did not differ (p > .1), with mean values ranging between 0.62 to 1.81 kg DM m−2. Root density in the tussock interspaces was greater in the mixtures (p < .001), regardless of seasons (p = .405) and years (p = .292). The mixtures were dominated by guineagrass (70%) and palisadegrass (30%) at the end of the experiment, with the population of ‘Basilisk’ and ‘BRS Paiaguás’ being completely suppressed throughout the experimental period. Mixing guineagrass and brachiariagrasses can be an alternative to the traditional pastoral systems in the tropics, as it does not compromise herbage production and presents a capacity to produce more roots than a very productive monoculture of ‘BRS Zuri’ guineagrass.  相似文献   

3.
This is the first report on the effect of light intensity and plant growth‐promoting rhizobacteria (PGPR) on the growth of a tropical forage grass, being a relevant study to improve pasture management in conventional farming and integrated crop‐livestock‐forestry systems. In this study, our aim was to evaluate the effects of light intensity and Burkholderia pyrrocinia and Pseudomonas fluorescens inoculation on Brachiaria brizantha cv. BRS Piatã growth, and phenotypic plasticity to shade. The experiment was conducted in a semi‐controlled environment. Seedlings of B. brizantha were allocated to full sun and shade. P. fluorescens and B. pyrrocinia were inoculated individually or co‐inoculated by soil drench, 14 days after seedling emergence. We evaluated morphogenesis, structural and growth parameters. Irrespective of the light regime, co‐inoculated plants had greater leaf area and SPAD index (chlorophyll content). Increase in total biomass production in co‐inoculated plants was over 100% and 300%, under full sun and shade respectively. Co‐inoculated P. fluorescens and B. pyrrocinia increased shade tolerance in B. brizantha, improving plant performance. Co‐inoculation promoted growth in B. brizantha under both sun and shade, indicating its potential as a bio‐fertilizer in conventional and integrated systems, especially in silvopastoral systems, where light availability to pasture growth may be limited.  相似文献   

4.
The use of forage legumes to contribute biologically fixed nitrogen (N) to pastures is an alternative to increase beef cattle production in tropical regions. The objective was to compare the impact of the introduction of a legume with that of N fertilizer application on forage and animal production in Brachiaria pastures. This two-year study assessed three pasture treatments: (1) mixed Marandu palisadegrass (Brachiaria brizantha [syn. Urochloa brizantha] cv. Marandu) and the legume “ovalifolium” (Desmodium ovalifolium) cv. Itabela (Mixed), (2) Marandu palisadegrass pastures with 150 kg N ha−1 (Fertilized), and (3) Marandu palisadegrass without N fertilizer (Unfertilized). Rotational stocking with a variable stocking rate was used with a target herbage allowance of 1.0 kg forage kg body weight−1. The pre-grazing green herbage mass was similar for Fertilized and Mixed pastures, with 54% and 63% more mass than Unfertilized pasture, respectively (p < .001). Cattle that grazed the fertilized pasture had the greatest average daily gain (ADG; p = .017). The stocking rate and liveweight gain per area were greatest for the Fertilized and Mixed pastures (p < .001 and p < .001, respectively). No differences between treatments were found for DM forage intake (p = .555). Organic matter digestibility was lowest (p < .001) for the Mixed pasture. The inclusion of the ovalifolium legume in the Marandu pasture had the same impact on beef cattle production as annual fertilization with 150 kg N ha−1. The potential and environmental benefits of ovalifolium are discussed.  相似文献   

5.
Efficient estimation of soil organic carbon (SOC) is vital for understanding and monitoring the effect of perennial fodder crops in conserving SOC. In subtropical regions, there is limited information on SOC accumulation and its allocation into different pools under long‐term grasses and legumes. Therefore, we investigated the dynamics of SOC in a 20‐year‐old field trial with seven perennial grass species and a legume in a Typic Paleudalf soil under subtropical climate in north‐east India by analysing oxidizable organic C (Coc) and its fractions of very labile (CVL), labile (CL), less labile (CLL) and non‐labile (CNL), microbial biomass C (Cmic) and mineralizable C (Cmin). Growing perennial fodder crops increased SOC in the 0–0.60 m soil depth from 19.9%–39.6% compared with the conventional cultivation with maize (Zea mays). The relative efficacy of the fodder species to SOC accumulation was Setaria sphacelata = Brachieria rosenesis > Panicum maximum cv. Makunia = Arachis pintoi > Panicum maximum cv. Hamil > Paspalam conjugalum = Pennisetum purpureum > Thysanolaena maxima. Among the analysed fractions, CVL, CL, CLL and Cmic were influenced most by the fodder crops and the active pools (CVL+CL) constituted 71.6% of the SOC. The results indicate that under the tested subtropical climate, soil under perennial grasses and legumes conserves organic C and that most of the SOC is in labile pools of short residence time.  相似文献   

6.
Theories suggest that incorporating alfalfa (Medicago sativa L.; Alf) or birdsfoot trefoil (Lotus corniculatus L.; BFT) into endophyte‐infected tall fescue (Festuca arundinaceas Schreb.; E+TF) pasturelands may improve livestock production. We investigated how planting configuration might influence plant secondary metabolites (PSM) and nitrogen concentration in these forages. Total nitrogen (N), in addition to condensed tannins (CT), saponins and ergovaline (EV), was compared in BFT, Alf and E+TF, respectively, when forages grew in monocultures and all possible two‐way “mixtures” using a block design with repeated measures in three blocks. Ergovaline (p < .01) and N (p < .001) concentrations in E+TF were greater when growing adjacent to legumes than when growing in monoculture, and N and EV concentrations in E+TF were positively correlated (r = .51; p = .001). No differences in saponins or CT were found when Alf or BFT grew in monoculture or in two‐way mixtures (p > .10). We conducted an in vitro trial to determine whether CT or saponins isolated from BFT and Alf, respectively, would bind to EV in water. Ergovaline bound to saponins to a greater extent (39%; SE = 0.25) than CT (5.1%; SE = 5.13; p < .05). Because EV was lower in E+TF monocultures than in E+TF–legume mixtures, and because CT and saponins may form complexes with EV which may alleviate fescue toxicosis, animals may benefit from systems which allow them to graze monoculture patches of E+TF and Alf or BFT rather than grass–legume mixtures.  相似文献   

7.
We aimed to evaluate the effect of soya bean oil (SBO) supplementation with different forages on in vitro gas production kinetics, methane (CH4) emissions and potentially digestible neutral detergent fibre (pdNDF) digestibility (IVpdNDFD). Samples of whole‐crop maize silage (MS; Zea mays), sugarcane (SC; Saccharum sp.), perennial ryegrass (RG; Lolium perenne), guinea grass (GG; Panicum maximum) and palisadegrass (PG; Brachiaria brizantha) were incubated with three concentrations of SBO (0, 30 and 60 g/kg of dry matter). The interaction between forage species and SBO inclusion affected molar proportion of acetate, acetate‐to‐propionate ratio, asymptotic gas and IVpdNDFD. Acetate‐to‐propionate ratio numerically decreased from 3.56 to 3.44 and 3.77 to 3.56 for MS and SC respectively. Soya bean oil inclusion at 60 g/kg DM decreased 21.2% and 12.9% of IVpdNDFD for MS and SC respectively. Soya bean oil increase did not affect IVpdNDFD for RG, GG and PG. Soya bean oil inclusion decreased quadratically the asymptotic gas (294–265 ml/g OM) for MS and increased linearly (275–283 ml/g OM) for GG. Lower and greater CH4 production was observed for RG and SC respectively. Methane production decreased quadratically by SBO increase. Soya bean oil inclusion linearly decreased CH4 concentration in total gas at 48 hr of incubation from 133 to 128 ml/L. In conclusion, MS and SC are more sensitive to adverse effects of SBO supplementation from 30 to 60 g/kg DM on rumen fermentation when compared to RG, GG and PG.  相似文献   

8.
Chestnut (Castanea sativa) shell and eucalyptus (Eucalyptus globulus) bark, waste products of the food and wood industries, respectively, were analysed as potential sources of antioxidant compounds. The extraction yield, the antioxidant activity and total phenols content of the extracts were greater in chestnut shell than in eucalyptus bark for most of the extraction conditions essayed. Extraction of chestnut shell with a 2.5% Na2SO3 aqueous solution led to the highest extraction yield, 25.6%, total phenols, 13.4 g gallic acid equivalent/100 g oven-dried shell, and FRAP antioxidant activity, 80.7 mmol ascorbic acid equivalent/100 g oven-dried shell. Extraction with methanol:water (50:50, v/v) provided the best results for eucalyptus bark. The antioxidant activity and the total phenols content of the extracts had a positive linear correlation. FTIR spectroscopy confirmed the higher content of phenolic compounds in chestnut shell extracts compared to eucalyptus bark extracts. Chestnut shell extracts were characterized by the presence of high molecular weight species whereas lower molecular weight species were predominant in eucalyptus bark extracts.  相似文献   

9.
New hybrid grass cultivars may enhance animal performance in forage-livestock systems if they possess traits that address edaphoclimatic challenges and pest susceptibility. The objective was to assess herbage accumulation, plant-part composition, nutritive value, and animal performance of ‘Ipyporã’ [Brachiaria ruziziensis Germ. & Evrard × B. brizantha (Hochst. ex A. Rich.) Stapf] and ‘Mulato II’ (B. ruziziensis × B. brizantha × B. decumbens Stapf) hybrids in the Brazilian Amazon biome. From May 2016 to May 2018, pastures were maintained under continuous stocking with variable stocking rates to maintain canopy height at 30-cm. Herbage accumulation (HA) was greater in Mulato II (17,370 kg dry matter [DM] ha−1 year−1) than Ipyporã pastures (14,930 kg DM ha−1 year−1) across the years. In Year 1, Mulato II had greater stocking rate (1685 vs. 1215 kg body weight [BW] ha−1) and greater gain ha−1 (1130 vs. 850 kg) than Ipyporã. However, in Year 2, both cultivars had similar plant and animal responses. The Year 1 ADG was similar among cultivars or seasons but in Year 2, rainy seasons had 21 and 77% greater ADG than dry seasons for Mulato II and Ipyporã, respectively. Both cultivars can contribute to the diversification of pasture-based livestock systems in humid tropical regions. Mulato II presented superior performance when soil moisture and fertility were not limiting (i.e., Year 1). However, both cultivars provide similar plant and animal responses in Year 2, offering viable alternatives for the diversification of pasture-based livestock systems in the Amazon Biome.  相似文献   

10.
In the moist mid‐latitudes of eastern Australia, soil water dynamics, herbage production and water use efficiency (WUE) were monitored during 2006–2008, for five perennial pastures: digit grass (Digitaria eriantha), Rhodes grass (Chloris gayana), forest bluegrass (Bothriochloa bladhii), native grass (Bothriochloa macra and Rytidosperma bipartita dominant), lucerne (Medicago sativa); and two forage crops: oat (Avena fatua) and sorghum (Sorghum bicolor). Ground cover formed more quickly in Rhodes grass and lucerne (>70% ground cover in 120 and 175 days after sowing [DAS] respectively) than in forest bluegrass and digit grass (245 and 365 DAS respectively). Values of maximum extractable water (MEW) for Rhodes grass and lucerne were similar (180–242 mm), while values for digit grass and forest bluegrass (129–175 mm) were equal to or greater than those for native grass, and two annual forage crops (77–144 mm). Lucerne expressed the maximum root depth (1.46 m), while values for the tropical grasses (0.96–1.39 m) were greater than native grasses and forage crops (0.87–0.96 m). Native grasses (6.5–12 t DM/ha) had the lowest herbage production, which resulted in values of WUE that were significantly less than most other treatments (16–21 vs. 23–43 kg DM ha?1 mm?1). Digit grass (33–34 kg DM ha?1 mm?1) had higher WUE compared with the other tropical grasses (20–27 kg DM ha?1 mm?1). The data collected here suggest that a forage system comprising digit grass, lucerne and forage oat would provide high production and WUE in this environment.  相似文献   

11.
Livestock production is the main source of livelihood in the arid and semi‐arid lands in Africa. However, desertification characterized by vegetation degradation and soil erosion is a major threat to the sustainability of land‐based production systems. Native rangeland forage species Cenchrus ciliaris L. (Buffel grass/African foxtail grass), Eragrostis superba Peyr. (Maasai love grass) and Enteropogon macrostachyus (Hochst. Ex A. Rich.) Monro ex Benth. (Bush rye grass) have been used to combat desertification. The objectives of the study were to identify the best‐suited native grass species to combat desertification in a semi‐arid environment in Kenya and to identify the preferred grass species among the agropastoralists in the area. Percentage basal cover, plant densities and frequencies of the three grasses in pure stands and mixtures were estimated. Grass species preferences were through household survey and focus group discussion. Results showed a significant difference (P < 0·05) in plant densities and cover estimates: E. macrostachyus was ranked first; C. ciliaris and E. superba were ranked second and third respectively. The agropastoral farmers, however, preferred E. superba followed by C. ciliaris and E. macrostachyus, a reverse trend. These results suggest that the choice of grass species to combat desertification is influenced more by its contribution as a source of forage for livestock than its contribution for rehabilitation purposes.  相似文献   

12.
Jacobaea aquatica (=Senecio aquaticus, Asteraceae), marsh ragwort, grows regionally in low management intensity wet grasslands in various European countries. The plant can be regarded as a noxious weed as it contains pyrrolizidine alkaloids (PAs), which cause health problems in livestock. In the Waldviertel region of Northern Austria, marsh ragwort has established dense populations as the fertilizing and production intensity of the meadows changed during the last decades. Ragwort biomass production and alkaloid concentration in J. aquatica were recorded during three consecutive years at three sites to study the effects of two treatments: cutting twice a year either early in June plus September, or in July plus August, respectively. Six PAs (Z‐erucifoline > senecionine > integerrimine > seneciphylline > acetyl‐erucifoline and acetyl‐seneciphylline) were evaluated. The alkaloid contents were highest in July and August when 600–1,400 mg/kg dry matter (DM) total PAs occurred in most ragwort samples. Consequently, the forage can easily be contaminated with 40–80 mg/kg DM of PAs and may present a health risk for domestic animals and also affect human health as these alkaloids are transferred into milk.  相似文献   

13.
A well‐established canopy is crucial for a stable mixed grass–legume forage pasture. The aim of this study was to assess a defoliation intensity that can ensure the establishment of mixed pasture of brachiaria grass (Brachiaria brizantha) intercropped with forage peanut (Arachis pintoi). The treatments comprised four canopy heights: 10, 20, 30 and 40 cm, maintained throughout the first 3 years of pasture establishment. Canopy structure, morphogenetic and structural characteristics were measured. A block design was used with four replicates, and seasons of the year were considered using repeated measurements over time. Light interception during the experimental period was 86.3%, 95.9%, 97.6%, and 99.1% for 10, 20, 30 and 40 cm of defoliation respectively (p < .001). Competition for light in taller canopies (at 30 and 40 cm) caused etiolation of forage peanut (greater internode, petiolate and stolon lengths). This response promoted its upward growth, leading to a lower stolon density compared with 10 and 20 cm. The treatment at 10 cm displayed a predominance of forage peanut (up to 0.614), potentially compromising community stability. Overall, the 20 cm canopy height showed a desired botanical composition (from 0.20 to 0.45 of legume in forage mass) and thus was considered an ideal defoliation intensity for establishment of mixed canopies of brachiaria grass and forage peanut.  相似文献   

14.
The common forage grass Lolium perenne has evolved with the systemic fungal endophyte Epichloë festucae var. lolii. The endophyte provides herbivore resistance to the grass due to defensive alkaloids, some of which are toxic to grazing livestock. In this field study, we determine whether distribution of the endophyte‐grass association changes along a land‐use intensity gradient on 87 managed grasslands in three German regions. Endophyte infections were detected in 66% of the studied sites and infection rates within infected sites ranged from 1% to 95%. Alkaloid concentrations of lolitrem B (vertebrate toxin) exceeded the toxicity thresholds in 50 (14%) of 351 infected plants and of peramine (invertebrate deterrent/toxin) in 12 (3%) of 351 plants. Infection rates and alkaloid concentrations were not significantly affected by land‐use intensity and region, but alkaloid concentrations were higher in summer compared to spring. We conclude that risks for livestock intoxication are currently low, as (i) average alkaloid concentrations per grassland were always below toxicity thresholds and as (ii) none of the grasslands was dominated by L. perenne. We suggest avoidance of grass monocultures in Europe to keep intoxication risks for livestock low; we also recommend regular examination of seeds and grasslands, as seed producers might accidentally distribute infected seeds, and as climate warming might further enhance the distribution of Epichloë endophytes in European grasslands.  相似文献   

15.
In the Southeastern United States, native warm‐season grasses (NWSG) are not harvested during autumn to rebuild root reserves, resulting in de facto stockpiled winter forage. Senesced NWSG forage is considered nutritionally inadequate by temperate livestock managers, but comparable forage is regularly utilized in rangeland systems. This experiment compared the forage characteristics of two NWSG pastures: switchgrass [Panicum virgatum L. (SG)] and a two species mixture of big bluestem/indiangrass [Andropogon gerardii Vitman/Sorghastrum nutans L. (BBIG)] to tall fescue [Festuca arundinacea Schreb. (TF)]. During two winter periods (January‐April), monthly samples were collected and measured for dry‐matter herbage mass (HM), crude protein (CP), in‐vitro true dry‐matter digestibility (48 hr; IVTDMD), neutral detergent fibre (NDF), NDF digestibility (dNDF) and lignin. Across sampling dates, TF provided adequate forage for low‐input animal maintenance (90.3 CP g/kg; 488 g IVTDMD/kg; 4,040 kg DM/ha), while SG had lowest nutritive values and greatest DM (21.0 g CP/kg; 366 g IVTDMD/kg; 7,670 kg DM/ha). Samples of BBIG had results intermediate to SG and TF (32.1 g CP/kg; 410 g IVTDMD/kg; 5,160 kg DM/ha). Leaf sub‐samples of NWSG indicated greater forage nutritive value compared to whole plant samples (e.g., SG: 65 vs 27 g CP/kg respectively). This indicates that selective grazing could allow superior outcomes to those expected from whole plant NWSG nutritive values. Although consistently nutritionally inferior to TF, further research could reveal strategies to make stockpiled NWSG economically useful to livestock managers.  相似文献   

16.
The use of stylosanthes in mixed grass-legume pastures may minimize the decline in forage quality and quantity that occurs in monoculture grass pastures, even though the availability of commercial cultivars in Brazil is still limited. The objective of the study was to evaluate the liveweight (LW) gain of young Nellore bulls in a mixed pasture of Brachiaria brizantha (cv. Paiaguás) with the latest release Stylosanthes guianensis cv. Bela. The study was conducted in Planaltina, FD, Brazil, from September to August in two consecutive years, right after seeding. The experimental design was a randomized complete block design with two treatments (mixed or monoculture Paiaguás pastures) and three replicates. The average daily gain (ADG) was on average greater in mixed pastures (0.436 vs. 0.350 kg head−1 day−1 in mixed and grass pastures respectively), particularly in the dry period (0.344 vs. 0.183 kg head−1 day−1). The benefit of mixed over monoculture grass pastures throughout the year was 22 kg LW/head and 55 kg LW/ha. The presence of stylosanthes increased the crude protein (CP) concentration in mixed pastures (120 g/kg) when compared to monoculture grass pastures (109 g/kg), probably influencing the ADG of bulls. The increase of liveweight gain, predominantly in the dry season, makes the high-protein stylosanthes cv. Bela an alternative to buffer the seasonal deficit of forage quality in newly seeded grass pastures.  相似文献   

17.
The short life span, irregular forage production and susceptibility to weed colonization of cool‐season grass–legume pastures are serious problems in grazing dairy systems in warm‐temperate regions. The inclusion of warm‐season species has the potential to mitigate these problems. In this study, we evaluated the effect of the inclusion of two warm‐season grasses with different growth habits on seasonal forage biomass, soil cover and weed colonization. Three different pasture mixtures were evaluated under grazing: conventional pasture (CP) [tall fescue (Festuca arundinacea), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus)], CP with Paspalum dilatatum and CP with Paspalum notatum (CP + Pn). Forage biomass and soil cover were sampled thirteen times during a 3‐year trial, and sampling times were grouped by season for the analyses. The mixtures with Paspalum showed higher soil cover in the autumn, while in the winter CP had higher soil cover than CP + Pn. Competition with tall fescue was similar between mixtures with Paspalum, when considering biomass, but it was higher in CP + Pn when considering soil cover. The inclusion of P. notatum increased biomass during the autumn but decreased the mixture performance during winter by reducing tall fescue soil cover. The addition of a warm‐season grass species with a moderate competing ability like P. dilatatum is likely to avoid a negative impact on the cool‐season component of the pasture.  相似文献   

18.
Mixed grass/legume pastures are an alternative to grass monocultures for increased beef cattle production in tropical climates. The objective of this study was to evaluate the productivity of beef cattle grazing either a mixed pasture of Brachiaria brizantha cv. Marandu grass and Arachis pintoi (forage peanut) cv. Belomonte or a Marandu monoculture, under rotational stocking. Five trials were conducted over a period of nine years in north-eastern Brazil where the sward structure (forage, grass and legume mass) and animal performance were compared for a mixed Marandu grass/forage peanut pasture, and a Marandu grass monoculture with 120 kg N ha−1 y−1. Stocking rate was adjusted to maintain forage allowance at 4% body weight/day. A block design was used with four replicates, and warm and cool seasons within each trial were considered, using repeated measurements over time. In the warm season, the forage mass in the mixed pastures was 17% greater than in the monoculture (p = .049), and the stocking rate, average daily gain and liveweight gain per ha were 16.4%, 20.0% and 28.7% greater (p = .004, p < .001 and p < .001 respectively). The average daily gain showed a positive linear relationship with the legume proportion in the sward (p < .001). The mixed forage peanut/Marandu pasture sustained significantly greater beef cattle production (789 kg ha−1 y−1) compared to the N-fertilized grass monoculture (655 kg ha−1 y−1). Appropriately managed, mixed pastures of forage peanut/Brachiaria pastures are sustainable and have high potential for use in the humid tropics.  相似文献   

19.
In this study, the influence of press cycle time and resin content (RC) on some of the physical and mechanical properties of single-layer particleboard manufactured from the low-quality raw materials were determined. Eucalyptus (Eucalyptus camaldulensis), mesquite (Prosopis juliflora), saltcedar (Tamarix stricta) and date palm (Phoenix dactylifera) wood, which is underutilized invasive species in southern parts of Iran, were used as alternative raw materials for particleboard manufacturing. Variable factors were as resin content (9, 10 and 11%) and press time (PT) (4, 5 and 6 min). Other parameters such as type of resin (UF), hardener content (2%), type of hardener (NH4Cl), press-closing time (4.5 mm/s), board density (0.75 g/cm3), press pressure (30 kg/m2) and press temperature (160 °C) were held constant. The experimental panels were tested for their mechanical strength including modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) and physical stability properties (thickness swelling) according to the procedures defined by European Union (EN) Standard. Overall results showed that most panels made from above-mentioned materials exceed the EN Standards for IB, MOE and MOR. The mechanical properties of particleboard were improved as the resin content increased from 9 to 11%. The results indicated that the polymerization of resin and wood is better at 11% resin content and 5 min of press time. However, thickness-swelling (TS) values were higher (poor) than requirements. Panels made of mesquite, saltcedar and date palm with a resin content of 11% and pressed for 5 min is adequate for general uses while eucalyptus with a resin content of 11% and pressed for 6 min is suitable for interior decoration.  相似文献   

20.
Eleven laboratory‐scale trials were undertaken in different years where ryegrass (Lolium perenne L.) or lucerne (Medicago sativa L.) were ensiled with different concentrations of tannin extracts (quebracho, Schinopsis balansae Engl., mimosa, Acacia mearnsii DE WILD.), and the effects on protein degradation were assessed. The dry‐matter (DM) content in grass silages ranged between 186 and 469 g/kg and in lucerne silages between 187 and 503 g/kg. Tannin extract, either quebracho or mimosa, was applied at 0–30 g/kg forage DM. Commercial additives such as Lactobacillus plantarum, formic acid or hexamine + NaNO2 were applied in two of the grass trials and in six of the lucerne trials. Eight of the trials incorporated a maximum ensiling duration of 90 or 180 days in addition to replicates which were opened and evaluated at earlier stages. All trials included silages which were assessed after at least 49 days of anaerobic storage. The crude protein (CP) fraction A (non‐protein nitrogen, NPN) as proportion of total CP, served as the main indicator for proteolysis. In ryegrass, in general, the level of proteolysis was lower than in lucerne. A correlation of DM content in silages and degree of proteolysis was only evident for ryegrass. In both forages, the degradation of true protein slowed considerably after 24 days of ensiling. True protein was conserved most with the highest level of tannin extract addition. However, in lucerne, the combination of formate with lactobacilli was equally effective up to 330 g DM/kg, and deamination was further inhibited by formic acid compared to tannin extracts.  相似文献   

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