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1.
Annual forage yields of intercrops of berseem clover (Trifolium alexandrinum L.) and oats (Avena sativa L.), as affected by timing of initial harvest and sowing rate of oats, were investigated. Berseem clover was intercropped with oats at 0, 30, 60, 90 and 240 plants m?2 of oats in 1999 and 2000 in Alberta, Canada. Cutting date treatments involved initial harvest at 10‐d intervals between 35 and 88 d after planting (DAP), and one or two subsequent harvests of regrowth. Total intercrop dry‐matter (DM) yield averaged 12·9–13·3 t ha?1 with proportions of 0·21–0·43 of berseem clover in the forage. Treatments with an initial cut at the silage stage of oats (76 DAP in 1999, 88 DAP in 2000, at about soft‐dough stage of oats) had greater yields of oats, lower yields of berseem clover, and lower proportions of berseem clover in total annual yields than treatments with an earlier initial cut. Total crude protein (CP) yield was greater with an initial cut at 65–66 DAP than with a silage‐stage initial cut. With an initial cut at 35 DAP (before stem elongation of oats) or after 65 DAP (after heading of oats), yield potential of oats was sometimes reduced compared with silage‐stage treatments, but this was balanced by a greater yield of berseem clover. The impact of harvest timing on total yield decreased as the proportion of berseem clover in the intercrops increased. With decreasing density of oats, DM yield of first‐cut intercrops and total DM yield of oats decreased, while regrowth and total DM yields of berseem clover increased. Intercrops with oats at 60 plants m?2 had equal or greater total DM and CP yields than intercrops with 240 plants m?2 of oats. For intercrops with oats at 60 plants m?2, with initial cuts at 65–66, 75–76, or 88 DAP, yields of regrowths were 0·30–0·35, 0·16–0·26 and 0·09 of the total yield respectively. Oats–berseem clover intercrops showed potential to manipulate the pattern of annual forage yield and to provide flexibility of harvest without reducing annual yields.  相似文献   

2.
The development of efficient forage management and utilization is facilitated by a knowledge of the changes in nutritive value and patterns of dry matter (DM) distribution within plants. The objectives of this experiment were to determine the patterns of DM accumulation and the change in nutritive value during maturation of crimson clover ( Trifolium incarnatum L.), a cool-season annual forage legume adapted to mild winter areas and acid soils. Crimson clover was established on a Dystric Eurocrept soil with pH 5·4 in Galicia, north-western Spain, during three consecutive years (1990–92). Shoot samples were taken at approximately biweekly intervals in the spring and summer after autumn sowing, and were separated into stems, leaves and seed pods. DM accumulation, crude protein (CP) and acid-detergent fibre (ADF) concentrations and in vitro organic matter digestibility (IVOMD) were determined for each plant part at each stage. Average annual DM production at initial flowering was 4·2 t ha–1, whereas the CP and ADF concentrations and IVOMD values were 134 g kg–1 DM, 302 g kg–1 DM and 0·720 respectively. The nutritive value declined with age, coinciding with a reduction in leaf:stem ratio (from 0·53 at the vegetative stage to 0·13 at the ripe seed stage). This decline was more rapid than that reported for other legumes, possibly because of the low leaf:stem ratio of crimson clover. However, as it is used in the Atlantic coastal areas of north-western Spain, where it is harvested around initial flowering, it can provide forage of good quality.  相似文献   

3.
Berseem clover (Trifolium alexandrinum L.) was sown as an intercrop with oats (Avena sativa L.) at 0, 30, 60, 90 and 240 oats plants m?2 in May in 1999 and 2000 in Alberta, Canada. Forage yield and quality were measured at 10‐d intervals between 35 and 88 d after planting (DAP). Yield is defined as the biomass above 6 cm of the soil surface. The dry‐matter (DM) yield of berseem clover in sole crops increased by 5–10 g m?2 d?1 between 35 and 55 DAP and then increased by 21–28 g m?2 d?1 between 55 and 75 DAP. The DM yields of oats sown at 240 plants m?2 increased by 26–28 g m?2 d?1 over the whole period from 35 to 75 DAP. Oats were the dominant component in the intercrops, even at low densities of oats. Berseem clover grown with 60 oats plants m?2 received only 0·24 of the incident light when shading by oats peaked at 65 DAP. DM yields of berseem clover in intercrops with 60 oats plants m?2 averaged 0·14–0·32 of the yields of berseem clover sole crops. Between 35 and 88 DAP in 2000, the crude protein (CP) concentration of berseem clover sole crops declined linearly from 310 to 180 g kg?1 DM, and the CP concentration of oats exhibited a quadratic response, declining from 350 g kg?1 DM at tillering to 110 g kg?1 DM at the soft dough stage. The mean CP concentration of berseem clover in intercrops with 60 oats plants m?2 was 25 g kg?1 less than in berseem clover sole crops, indicating that competition by oats reduced the CP concentration of berseem clover. At later sampling dates, CP and DM yields of intercrops with oats at 60 plants m?2 equalled those with oats at 240 plants m?2. The addition of berseem clover to oats in intercrops at 60 oats plants m?2 reduced the neutral‐detergent fibre concentration by 30 g kg?1 DM compared with oats alone. Oats were very competitive as a companion crop for berseem clover. Adding berseem clover to oats increased forage quality and may provide for increased intake and digestibility of forage to support higher livestock productivity.  相似文献   

4.
Dorycnium hirsutum and D. rectum are perennial legumes which may have potential for use as pastures for the control of groundwater recharge in southern Australia. Little is known about the quality of the forage of Dorycnium species for grazing livestock or how these species respond to cutting. The effect of cutting height on plant survival, production of dry matter (DM), the proportion of leaf, edible stem (approximately <5 mm diameter) and woody stem in the DM and the nutritive value of the edible components was investigated. Biomass above five cutting‐height treatments (uncut, ground level, 5–8 cm, 10–15 cm and 15–30 cm above ground level) was removed at 8‐week intervals from plots of D. hirsutum and D. rectum from September 2002 to July 2003. In both species, plants subjected to lower cutting height treatments produced less DM above the height of the cut than those cut at higher heights. DM production declined over time in all treatments. Plants cut to ground level failed to regrow after the second harvest in D. hirsutum and the fourth harvest in D. rectum. Thus, these Dorycnium species were susceptible to high severity defoliations at 8‐week intervals. Negligible inedible woody stem was present in regrowth of both species after 8 weeks but D. hirsutum regrowth had a higher proportion of leaf (0·72) than D. rectum (0·56). Plants left uncut accumulated a large proportion of inedible woody stem in the DM (0·69 in both species) by July 2003, particularly at the base of the plant. Edible DM from regrowth of D. hirsutum and D. rectum had crude protein (CP) concentrations of 120 and 150 g kg?1 DM; dry matter digestibility (DMD) values of 0·45 and 0·58; organic matter digestibility (OMD) values of 0·50 and 0·64; neutral‐detergent fibre (NDF) concentrations of 370 and 290 g kg?1 DM; and acid‐detergent fibre (ADF) concentrations of 260 and 210 g kg?1 DM, respectively. Medicago sativa, grown under similar conditions, had higher digestibility values (0·63 DMD and 0·66 OMD) and similar CP concentrations to D. rectum (140 g kg?1 DM), but higher concentrations of NDF and ADF (410 and 290 g kg?1 DM). Leaf material from both Dorycnium species had a higher nutritive value than edible stems, with DMD and OMD values of leaf of D. rectum being 0·68 and 0·74 respectively. Uncut plants had a much lower nutritive value of edible DM than the regrowth from cut treatments; older material was also of a lower nutritive value. The relatively low nutritive value of even the young regrowth of Dorycnium species suggests that forage quality is a major limitation to its use. Forage of Dorycnium species could be used during periods when other sources of forage are in short supply but infrequent grazing it is likely to produce forage of a low nutritive value.  相似文献   

5.
Six annual legumes were evaluated as components of cereal-grass-legume intercrops in two experiments at two sites differing in elevation by 789 m. Barley (Hordeum vulgare L.) and Westerwolds rye-grass (Lolium multiflorum Lam.) were seeded on all intercrop plots. Dry-matter (DM) yield, crude protein (CP) and organic matter digestibility (OMD) were measured. DM yield and N content were used to estimate legume N fixation. Experiment 1 was conducted at both sites. At the lower site, Persian clover (Trifolium resupinatum L.) and annual alfalfa (Medicago sativa L.) accounted for 70% of the DM yield in harvest 1 (July), increased CP and OMD, but did not affect intercrop yield. They increased harvest 2 (August/September) intercrop yield by 263% and CP concentration by 65 g kg?1 DM. They increased harvest 3 (October) yield by 275% and CP concentration by 78 g kg?1 DM. Inclusion of striate lespedeza (Lespedeza striata) did not affect intercrop yield or quality. Annual legumes failed to establish at the higher elevation site and therefore had no effect on DM yield or forage quality. In Experiment 2, in which the performance of Westerwolds ryegrass was also compared with that of Italian ryegrass, and conducted at the lower site only, Persian clover and berseem clover (T. alexandrinum L.) increased CP of all three of the year's harvests. These two species contributed 29% of the DM yield in the first harvest (July) but did not affect total intercrop yield. They increased harvest 2 (August) yield by 313%. Persian clover increased harvest 3 (October) yield by 318% and berseem clover increased harvest 3 yield by 405%. Barrel medic (Medicago truncatula) and snail medic (M. scutellata) contributed 29% of harvest 1 yield, and increased both DM yield and CP content. Medics did not regrow. Aubade Westerwolds ryegrass contributed a greater percentage of the DM yield than did Maris Ledger Italian ryegrass at harvests 1 and 2. Ryegrass type did not affect total DM yield but did affect forage quality; intercrops containing the Italian ryegrass had higher CP at harvest 2 and higher OMD at harvest 3 than those containing the Westerwolds ryegrass. Over both experiments, at the lower elevation site, stands with Persian clover, berseem clover or alfalfa produced 80% of the yield of barley-ryegrass receiving 250 kg N ha?1, and 165% of the yield of unfertilized barley-ryegrass. Berseem and Persian clover fixed about the same amount of N over the growing season; 188 kg N ha?1 in Experiment 1 and 134 kg N ha?1 in Experiment 2.  相似文献   

6.
Forage crops in Mediterranean environments are characterized by variable seed and forage production. Knowledge of the effects of agronomic factors on annual clovers grown in pure stand and in association with grasses is essential for their effective exploitation of the available environmental resources. Herbage and seed production were evaluated in southern Italy in an experiment with winter annual forage crops during the years 1992–95. Clovers (Trifolium alexandrinum L., berseem; T. incarnatum L., crimson; T. resupinatum L., Persian; and T. squarrosum L., squarrosum) and graminaceous forage crops (Hordeum vulgare L., barley; and Lolium multiflorum Lam., Italian ryegrass) were used to examine the agronomic effects of irrigation and harvest management. The clovers were evaluated in pure stand and in mixture, whereas the graminaceous species were evaluated only in mixtures. The mixtures were sown in alternating, equally spaced rows. The parameters evaluated were forage dry-matter yield, seed yield and its components. The results showed wide differences in forage production between clovers in pure stands and in binary mixtures. Mean dry-matter production from forage harvest of pure stands of irrigated clovers taken when 10–15% of the stems were flowering yielded 4·36 t ha–1, that is 0·67 and 0·55 of that of irrigated mixtures of clovers with either Italian ryegrass or barley, respectively, harvested when 10–20% of the graminaceous components were at the heading stage. The forage yield of non-irrigated pure stands of clovers was 0·60 of that of irrigated plots, whereas non-irrigated mixtures yielded 0·82 and 0·86 of that the irrigated treatments for Italian ryegrass or barley mixtures. The mean seed yield of non-irrigated pure stands of the clovers was 0·51 of that of irrigated stands, which yielded 451 kg ha?1. Persian clover gave the highest seed yields (732 kg ha?1 under irrigation). These higher yields were related to a higher number of fructiferous organs per stem in Persian clover. When a forage harvest had previously been taken on irrigated clover plots, the subsequent mean seed yields were greatly reduced to 0·76 for berseem and 0·21 for Persian clover and were almost negligible for crimson and squarrosum clover. When irrigated and grown in mixtures with Italian ryegrass, only berseem produced a worthwhile yield of 0·36 compared with that of pure clover taken for seed without a forage harvest; mixtures with barley gave yields of 0·71, 1·07 and 0·20 for berseem, crimson and Persian clovers, respectively, compared with seed yield from uncut pure clover.  相似文献   

7.
Abstract Cerastium holosteoides is a short‐lived plant often found in small proportions on dry and mesotropic semi‐natural, species‐rich grassland communities. To obtain more information about its nutritive value, two experiments on Arrhenatheretum elatioris grassland were carried out to examine the effect of harvest date on in vitro organic matter digestibility (IVOMD), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), acid‐detergent lignin (ADL), estimated net energy for lactation (NEL) and crude protein (CP) concentrations of C. holosteoides, and selection of this plant by dairy cows grazing on semi‐natural grassland. C. holosteoides starts flowering in spring and continuously develops new flowers on new branches throughout the summer. Harvests were made in relation to particular growth stages of Dactylis glomerata present in the sward: (A) tillering; (B) stem elongation; (C) ear emergence; (D) flowering; and (E) ripening. Chemical composition and nutritive value were evaluated in 1998 and 1999. With advancing maturity, IVOMD of C. holosteoides decreased from 0·771 at growth stage A to 0·485 at growth stage E. At the same time, CP concentration decreased from 153 to 69 g kg?1 dry matter (DM) and estimated NEL concentration from 6·00 to 4·07 MJ kg?1 DM. With advancing maturity, there was a significant increase in NDF, ADF and ADL concentrations. In the summer harvest season, C. holosteoides contained significantly higher NDF, ADF and ADL concentrations, lower NEL concentration and had a lower IVOMD value than in the spring. Differences between years were also found for IVOMD and for NDF, ADF, ADL and NEL concentrations. In a grazing experiment in the year 1999, at growth stage B, Simmental cows grazed an A. elatioris sward in which the main species was D. glomerata (0·092), and the proportion of C. holosteoides was 0·034. C. holosteoides was, on average, grazed by cows to the same relative extent as other species in the sward.  相似文献   

8.
Monocultures of thirteen perennial C3 grass species that co‐occur in temperate semi‐natural grassland communities in Europe were compared in a factorial field design of two levels of N supply and two levels of cutting frequency. Above‐ground yield of dry matter (DM), crude protein (CP) concentration and pepsin‐cellulase DM digestibility of herbage were measured in two successive years. Species was the largest source of variability in yield of DM and DM digestibility of herbage, while CP concentration of herbage responded more to management factors. The highest mean DM yields and values of DM digestibility of herbage were achieved in spring for Festuca arundinacea and in autumn for Phleum pratense. Poa trivialis and Festuca rubra had the lowest DM yield and DM digestibility values, respectively, regardless of seasons and treatments. For all species CP concentration in herbage increased in response to an increase in cutting frequency and N supply by an average of 46 and 34 g kg?1 DM respectively. Differences between years and seasons indicated the importance of plant phenology on nutritional variables and the influence of environmental factors on species performance. Species ranking was compared according to their annual digestible DM and CP yields. The results show that some grasses have a nutritive value which is comparable to that of forages selected for high yields.  相似文献   

9.
Excellent winter hardiness, persistence and nutritive value of both kura clover (Trifolium ambiguum M. Bieb.) and reed canarygrass (Phalaris arundinacea L.) suggest that intercropping these species could substitute for lucerne (Medicago sativa L.). The dry matter (DM) yield and nutritive value of herbage, and silage characteristics of kura clover‐reed canarygrass (KC‐RCG) herbage, were compared to those of lucerne over two growth cycles near Arlington, WI, USA. First and second growths of lucerne and KC‐RCG herbage were sampled four times at 1‐week intervals and ensiled for 100 d. Yield of DM of the KC‐RCG was 0·23–0·57 greater than that of lucerne on sampling dates in the first growth cycle, with no differences in DM yield in the second growth cycle. The pH of lucerne silage was lower than that of KC‐RCG silage in the first growth, and the opposite occurred in second growth, which was attributed to maturity differences and the proportion of kura clover in the mixture. Lactate concentration was lower in KC‐RCG than lucerne silages in both growth cycles. The lucerne and KC‐RCG silages had similar in vitro DM digestibility except for the final sampling date in the first growth cycle when neutral‐detergent fibre concentration of KC‐RCG herbage exceeded 550 g kg?1 DM. Crude protein concentration was greater in lucerne silage than in KC‐RCG silage in both growth cycles. Overall, differences in nutritive value and silage fermentation between the two herbages were minimal across growth cycles. These results suggest that a KC‐RCG sward is a viable alternative to lucerne in northern environments of the USA where lucerne production may be limited by winter injury or edaphic factors.  相似文献   

10.
Persistence of white clover (Trifolium repens) in mixtures was studied in a long-term experiment. Mixtures of two cultivars of perennial ryegrass (Lolium perenne) with contrasting growth habits and three white clover cultivars differing in leaf size were sown in 1991 and evaluated at two cutting frequencies. During 1995 and 1996 mixtures with large-leaved white clover cv. Alice had the highest dry-matter (DM) content, clover and N yield, and the highest white clover content, and mixtures with medium-leaved Retor the lowest, whereas mixtures with small-leaved Gwenda yielded most grass DM. In 1995 averaged over cutting treatments and mixtures, the mixtures yielded 11·8 t DM ha?1 with a white clover content of 0·6; the apparent N fixation was 393 kg N ha?1. In 1996 these values declined to 8·5 t DM ha?1, 0·48 white clover and 236 kg N ha?1. There was no significant effect of cutting frequency on DM yield or white clover content, whereas the effects of grass cultivar were not consistent. In spring there was a peak in the DM production of the mixtures, coinciding with a peak in production of the grass component. However, in summer and autumn the seasonal pattern of DM production of the mixtures was similar to that of the white clover component. Both cultivars of perennial ryegrass showed the same seasonal response, but the seasonal growth pattern of white clover differed slightly between clover cultivars and cutting treatments. In later years only one cutting frequency was imposed, and no yield measurements were taken. White clover was judged to have performed well during 1997; the clover content in September was very high (0·76), whereas in October 1998 it was 0·45. Mixtures with Alice contained most white clover. Despite fluctuations in white clover content during 1991–98, all clover cultivars had persisted 7 years after sowing, irrespective of companion grass cultivar, at both cutting treatments.  相似文献   

11.
Silvopastoral systems in the Appalachian region of the USA could increase the carrying capacity of livestock and contribute to a reliable supply of high‐quality herbage. In 2000, 2001 and 2002, the influence of solar radiation [0·20, 0·50 or 0·80 of maximum solar radiation (MSR); treatments 20‐, 50‐ and 80‐MSR respectively] on the productivity and nutritive value of a mixture of sown grasses and legumes established under a mature stand of conifers was investigated. Yields of dry matter (DM), crude protein (CP), total non‐structural carbohydrates (TNC) and total digestible nutrients (TDN) were greater for the 80‐MSR treatment except in 2000 when DM yield did not differ. As a proportion of the sward, introduced species (Dactylis glomerata L., Trifolium repens L., and Lolium perenne L.) increased over time for the MSR‐80 treatment, corresponding with a decrease in the proportion of bare area and of non‐introduced species. CP concentration of herbage was 207 g kg?1 DM or greater across treatments and years with higher concentrations on the 20‐ and 50‐MSR treatments. Herbage from the 80‐MSR treatment had a greater concentration of TNC than that of the 20‐ and 50‐MSR treatments. Estimated concentration of TDN was similar for all treatments in 2000 and greater for the 80‐MSR treatment than the other two treatments in 2001 and 2002. High CP concentrations in herbage, as a result of appropriate thinning of trees in an Appalachian silvopastoral systems, could be utilized as a protein supplement to herbage with low CP and higher fibre concentrations.  相似文献   

12.
In a field experiment, the effects of different management treatments on the botanical development and productivity of a previously species‐poor, intensively managed, lowland permanent grass sward were investigated over a 4‐year period. Fertilizer inputs were stopped and nine main treatments, based on three pre‐sowing and three post‐sowing cutting regimes, were applied. Half of each treatment plot was oversown with a mixture of forb (wildflower) species and half left unsown. The aims were: (1) to investigate the effect of cutting regimes on the establishment of introduced forb species, (2) to assess the development and dry‐matter (DM) yield potential of these introduced species, and (3) to compare the DM yield and forage quality of swards with and without introduced species. Seedling establishment was recorded until the end of the second year. From the third year onwards, a common twice‐yearly cutting regime was imposed on all treatments, and the development of the introduced species was recorded. The DM yield of the nine oversown sub‐treatments was compared with the sub‐treatments not oversown. Frequent cutting after oversowing resulted in the greatest number of established plants and three times greater harvested DM yield of introduced species, compared with infrequent cutting. Plantago lanceolata and Trifolium pratense were the best performing introduced species. By years 3 and 4, there was proportionately 0·15 and 0·23, respectively, additional herbage DM yield harvested from the oversown treatments compared with unsown treatments, and up to 0·60 more in some treatments. The introduction of forbs increased the crude protein concentration, but decreased the digestibility of the forage.  相似文献   

13.
The effect of defoliation interval on growth patterns of contrasting perennial ryegrass (Lolium perenne)–white clover (Trifolium repens) mixtures was studied. The dynamics of increase in leaf area, light interception and dry-matter (DM) production were measured within successive regrowth periods. No N fertilizer was applied. During 1995 six mixtures were cut eight (F1) or six times (F2) at a stubble height of 5 cm. The stubble composition was stable throughout the growing season: after harvest about 50 g DM m?2 (with a white clover proportion of 0·52) was present with a leaf area index (LAI) of 0·5 (0·38 white clover). The percentage of intercepted radiation after cutting was 20–30% and increased during 3 weeks to about 95%. The relative growth rate of leaf area and DM was higher for white clover than for perennial ryegrass, with the proportion of clover in the LAI and DM increasing during each regrowth period. Mixtures with large-leaved white clover cv. Alice had a lower initial clover content after harvest, but a more rapid increase in clover LAI and DM than mixtures with the smaller leaved cvs Gwenda or Retor. Alice had the highest total and clover LAI and DM at harvest. Cutting frequency affected the change in white clover–perennial ryegrass ratio during regrowth. This was significantly higher in mixtures with Alice than in mixtures with Gwenda, but only under less frequent cutting (F2). In spring there was a mean white clover proportion of about 0·55 in the LAI and 0·45 in the total harvested DM. In summer the white clover proportion in the LAI and DM increased to 0·70–0·75. There was a decline during autumn, especially in F2 and in the mixtures with the small-leaved white clover cv. Gwenda and the medium-leaved cv. Retor. In contrast, grass DM and LAI declined from spring to summer. The decline in clover LAI in autumn was similar in Alice and Gwenda at frequent cutting (F1), but stronger in Gwenda in F2. Retor had the lowest clover specific leaf area (SLA). The SLA values of Alice and Gwenda were similar, SLA being similar between cutting treatments. No differences were found for leaf weight ratio (LWR) among the three white clover cultivars or between the grass cultivars, and LWR was not affected by cutting treatment. Defoliation interval had limited effects on the growth pattern and leaf characteristics of perennial ryegrass–white clover mixtures.  相似文献   

14.
The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4–7 years of treatment imposition. Both experiments had a split‐plot design with four replicates. In Experiment 1 the three main‐plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub‐plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N1PK) and application of PK plus N applied to each of two, three or four cuts (Nc PK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four‐cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut.  相似文献   

15.
In vitro ruminal fermentation techniques rely on the availability of fistulated ruminants for rumen fluid (RF), a major constraint for resource‐poor institutions. An alternative would be to use faecal microbes. This study was therefore designed to compare the potency of fresh bovine faeces against RF as sources of microbial inocula for fermenting six contrasting tropical forages using the Tilley and Terry (Journal of British Grassland Society, 18 , 104–111) technique. Faecal inocula were prepared at concentrations of 250 g (Faec250), 300 g (Faec300), 350 g (Faec350), 400 g (Faec400) and 450 g (Faec450) fresh cow faeces per litre bicarbonate buffer. In vitro organic matter digestibility (IVOMD) increased with increasing concentration of faeces at 12‐, 24‐ and 48‐h incubation intervals. All faecal inocula except Faec450 had lower potency when compared with RF at all incubation intervals. Digestibility of forage substrates with Faec450 (533 ± 23 g kg?1 DM IVOMD) was comparable to RF (566 ± 5 g kg?1 DM IVOMD) after 48‐h incubation. Faec450 showed greater potency on more fibrous and low‐protein substrates than RF. The coefficient of determination of the regression models for predicting 12‐, 24‐ and 48‐h RF IVOMD from Faec450 were 0·914, 0·75 and 0·756 respectively. It was concluded that inocula prepared from 450 g cow faeces demonstrated great potential as a substitute and predictor for RF in 48‐h IVOMD assays of tropical forages.  相似文献   

16.
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   

17.
The addition of cool‐season, tall fescue [Lolium arundinaceum (Schreb.) Darbysh.], to warm‐season, bermudagrass [Cynodon dactylon (L.) Pers.], pastures can improve forage productivity and nutritive value. Effects of four binary mixtures consisting of cv. Flecha (incompletely summer dormant) and cv. Jesup (summer active) tall fescue overseeded into established stands of cv. Russell and cv. Tifton 44 bermudagrass and three seasonal N treatments were evaluated on dry‐matter (DM) yield, crude protein (CP), in vitro true digestible DM (IVTDDM), acid detergent fibre (ADF) and neutral detergent fibre (NDF). Nitrogen‐timing treatments were 168 kg N ha?1 (as ammonium nitrate) split into three applications per season with an additional 8·6 t ha?1 of broiler litter (as‐is moisture basis) split into two applications varied to favour either tall fescue (in October and January), bermudagrass (in March and May) or both grasses (in January and March). Treatment effects were determined in samples of mixed herbage harvested in April, May, July, August and September of 2009 and 2010. Regardless of bermudagrass cultivar, herbage DM yield was greater (P < 0·05) in Flecha–bermudagrass than Jesup–bermudagrass in July of both years and in August 2010. Nutritive value generally was greatest in Jesup–Tifton 44, based on high CP and IVTDDM, and low ADF and NDF. Averaged across mixtures, avoiding fertilizer N and litter applications beyond April increased (P < 0·01) DM yield in April and May and IVTDDM in July (603 vs. 629 g kg?1; 2‐year average) and August (618 vs. 660 g kg?1) compared with applications in January–July. The timing of N and broiler litter applications on tall fescue–bermudagrass to favour growth of tall fescue appeared to increase fescue cover during the cool season and nutritive value of the mixed herbage during the warm season.  相似文献   

18.
Kudzu [Pueraria lobata (Willd.) Ohwi.], a vigorous, perennial warm‐season legume, grows widely throughout the south‐eastern United States, predominantly as a volunteer species. It is tolerant of drought and acidic, infertile soils and may have potential as a low‐input forage for livestock. A field experiment was undertaken to determine the effects of cutting date and frequency on yield and nutritive value of kudzu (20‐year‐old stand with no fertilizer or lime inputs) in central Georgia. The cutting treatments included an uncut control, and plots cut once (September), twice (July and September), and three times (June, July, and September) during the 1994 growing season. Dry matter (DM) production and forage quality were determined for total herbage, leaf and stem tissues from quadrat samples taken on all plots in June, July, September, and November (after a killing frost) in 1994, and in June, 1995. Total herbage and leaf DM production was highest for the three‐harvest system and lowest in the no‐cut control plots in 1994, but these results were reversed in the harvest made in 1995. Total herbage production and crude protein concentrations were similar in kudzu cut in the initial summer harvest (either June, July, or September) during the first year. Whole plant and stem in vitro dry matter digestibility (IVDMD) in these samples declined throughout the growing season, while leaf IVDMD was unchanged until the first frost. Kudzu has the potential to be a low‐input forage for livestock, particularly as supplemental drought feed, or as a protein bank for summer or autumn grazing.  相似文献   

19.
Agronomic data on most broad‐leaved species of grasslands are scarce. The aim of this study was to obtain novel information on herbage DM yield and forage quality for several forb species, and on species differences and seasonal patterns across harvests and in successive years. Four non‐leguminous forbs [salad burnet (Sanguisorba minor), caraway (Carum carvi), chicory (Cichorium intybus) and ribwort plantain (Plantago lanceolata)] and three leguminous forbs [yellow sweet clover (Melilotus officinalis), lucerne (Medicago sativa) and birdsfoot trefoil (Lotus corniculatus)] and a perennial ryegrass–white clover mixture were investigated in a small‐plot cutting trial in Denmark during 2009 and 2010. Plots were harvested four times per year. On average, annual herbage yield was highest for lucerne (15·4 t DM) and grass–white clover (12·5 t DM ha?1), and lowest for salad burnet (4·6 t DM ha?1) and yellow sweet clover (3·9 t DM ha?1). Ribwort plantain and lucerne had the highest concentrations of acid detergent fibre (339 and 321 g kg?1 DM respectively) and lignin (78 and 67 g kg?1 DM respectively); contents in other species were similar to grass–white clover (275 and 49 g kg?1 DM respectively). No common feature was found within the functional groups of non‐leguminous forbs and leguminous forbs, other than higher crude protein contents (198–206 g kg?1 DM) in the legumes. DM yield and fibre content were lowest in October. Digestibility declined with higher temperature and increasing fibre content. Results are discussed in terms of the potential of forbs to contribute to forage resources in farming practice.  相似文献   

20.
Six red clover cultivars, three diploid—Essex, Sabtoron and Violetta—and three tetraploid— Teroba, Red Head and Hungaropoly—were sown alone and with each of three companion grasses—timothy (S48), tall fescue (S170) and perennial ryegrass (S24). The productivity and persistency of the red clover cultivars were compared over 4 years. Dry matter (DM) yield, DM digestibility and the crude protein (CP) concentration were assessed and botanical analyses conducted on herbage samples from each treatment at each of three harvests per annum. Annual fertilizer application consisted of 165 kg P and 312 kg K ha-1. Comparing clover cultivars alone Essex was significantly less productive and less persistent than the other five cultivars. Yield and persistency of the five other cultivars did not differ markedly within years with the exception that the diploids were significantly less productive than the tetraploids in the fourth year. Over all 4 years mean annual total DM and clover DM yields of the five cultivars were between 12·2 and 13·2 t ha-1 and between 9·2 (79·2% of total DM yield) and 10·2 (83·2%) t ha-1 respectively, and differences were not significant. Up to the end of the third year there was little or no advantage gained by the inclusion of a companion grass, annual total DM yields being between 11·2 and 14·2 t ha-1 for clover alone and between 10·2 and 14·2 t ha-1 for clover-grass mixtures. In the fourth year there was an overall tendency for the yield of the clover alone to be lower, between 7·2 and 12·2 t ha-1, than that of the clover-grass mixture, between 8·2 and 13·2 t ha-1, and this was more pronounced with the diploid than with the tetraploid clover cultivars. Sown with companion grasses, Essex and Hungaropoly were lower in yield and in contribution than the other cultivars over the 4 years. The influence of the companion grass on total dry matter yield showed that the contribution of timothy was low relative to that made by tall fescue and perennial ryegrass. Perennial ryegrass made the most varied contribution from year to year. Tall fescue was the most consistent contributor with all clover cultivars and at the end of 4 years both yield and clover-grass balance had not changed materially. No pronounced differences in DM digestibility were evident between treatments. Crude protein concentration of the pure clover was similar to that of the clover-timothy treatments and both would appear to be superior to either the clover-perennial ryegrass or clover-tall fescue mixtures. It is considered that red clover dominant swards are suitable for use under a cutting regime and can provide high yields of DM at a low cost for up to 4 years. Such swards are self-sufficient in N and in addition soil N accumulation can be exploited in the production of succeeding crops.  相似文献   

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