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1.
The rates of drying of herbage, cut from perennial ryegrass (Lolium perenne L.) – dominant swards and subjected to different treatments, were investigated under field conditions by changes in weight of herbage in wire mesh trays in 1995 and 1996. A series of replicated factorial experiments studied the effects, in different combinations, of intensity of conditioning achieved by passing the cut herbage through a laboratory‐scale macerator zero (0C), once (1C), three (3C) or six (6C) times; weight of herbage per unit area equivalent to 450, 675 and 900 g dry matter (DM) m?2. In one experiment, pressing the herbage to form a mat was incorporated into the experimental design. A further experiment investigated the effect of varying the proportion of conditioned herbage in the herbage mass from 0·00, 0·25, 0·50, 0·75 and 1·00 on drying rate. On each occasion the trays plus herbage were weighed at hourly intervals over an ≈6‐h period and the DM content of the herbage estimated from the change in weight. On all occasions, conditioning and weight of herbage per unit area significantly (P < 0·001) influenced herbage drying rate. Lowering the weight per unit area of both unconditioned and conditioned herbage increased the rate of moisture loss. Unconditioned herbage at the equivalent of a herbage mass of 450 g DM m?2 had a total moisture loss that was on average 1·5–1·8 times greater than unconditioned herbage at the equivalent of a herbage mass of 900 g DM m?2. Similarly, conditioned herbage at the equivalent of a herbage mass of 450 g DM m?2 had a total moisture loss that was 1·8–2·3 times greater than unconditioned herbage at the equivalent of a herbage mass of 900 g DM m?2. Increasing the level of conditioning produced a non‐linear response in rate of moisture loss, consequently 3 passes through the macerator produced >0·95 of the total moisture loss that was produced by 6 passes through the macerator. Increasing the proportion of conditioned herbage in the herbage mass increased rate of moisture loss and consequently final DM content (P < 0·001) although there was little effect from increasing the proportion of conditioned herbage above 0·75. The effects of conditioning and weight of herbage per unit area treatments on total nitrogen , water‐soluble carbohydrate and acid‐detergent fibre concentration of the herbage were small.  相似文献   

2.
The aims of this study were to examine the effect of three grazing treatments (year‐round stocking rates of 0·8 ewes ha?1, 0·5 ewes ha?1 and 0·5 ewes ha?1 plus grazing cattle in summer), imposed for 4 years, on the herbage mass and surface height of a Nardus stricta‐dominated grassland in western Scotland and to obtain estimates of annual productivity of this grassland. Nardus stricta‐dominated grassland comprised proportionately 0·20 of the grazing area. Stocking rate of sheep had no significant effect on the herbage mass of the grassland in the first 2 years of the experiment, although mean summer pasture heights were significantly higher under the lower stocking rate of sheep. The pasture on the treatment with cattle grazing in summer had a significantly lower herbage mass and lower surface height than the two sheep‐only grazing treatments. Year‐to‐year variation in the herbage mass and surface height of herbage in summer was greater than the effect of treatments. Despite changes in surface height, the structural diversity of the grasslands was not increased by the treatments. The annual production of vascular plant material ranged from 417 g DM m?2 in 1994 to 628 g DM m?2 in 1996.  相似文献   

3.
This study investigated the effect of ewe prolificacy potential (PP; predicted number of lambs born ewe?1 year?1), stocking rate (SR; ewes/ha) and their interaction on herbage dry matter (DM) production, utilization, quality and sward morphology within a temperate grass‐based lamb production system. The study had a 2 × 3 factorial design, consisting of two ewe PP as dictated by sire breed (180 medium prolificacy potential (MP—Suffolk crossbred) and 180 high prolificacy potential ewes (HP—Belclare crossbred)) and three SR: low (LSR; 10 ewes/ha), medium (MSR; 12 ewes/ha) and high (HSR: 14 ewes/ha). Each treatment was managed in a rotational grazing system, with LSR, MSR and HSR treatments grazing to target post‐grazing sward heights (PGSH) of 4.55, 4.15 and 3.75 cm respectively. Herbage DM production (above target PGSH) and utilization were highest at the HSR, intermediate at the MSR and lowest at the LSR (p < .001). Ewe PP had no effect on herbage DM production, utilization, quality or sward morphology (p > .05). The proportion of leaf in the sward (above target PGSH) was 4% greater in MSR and HSR compared with LSR (p < .05). In conclusion, findings demonstrate the potential to support increased ewe PP through the selection of ewe genotypes of a genetically higher PP and lower mature live weight and increased SR within a temperate grass‐based lamb production system.  相似文献   

4.
Demand for livestock food products is projected to increase dramatically through to 2050. Increased livestock production capacity on marginal lands will be critical to meeting this demand. A 5‐year research effort was undertaken to evaluate lamb and sward productivity within open and hardwood silvopasture (SP) systems in Appalachia, USA. Grazing began in mid to late April each year, with the grazing season averaging 141 d. Grazing system treatments during 2002 and 2003 grazing seasons were as follows: 100% open pasture (OP), 67% OP and 33% SP, and 67% OP and 33% SP with delayed SP grazing initiation (OSD). In 2004, a 100% SP (SP) system was added. Animals were rotationally stocked through either 6 (2002–2004) or 7 (2005–2006) paddocks. Open pasture produced greater (P < 0·001) grazing season herbage yield, while all systems generated similar animal performance. Based on summer solstice, herbage production in spring was greater (P < 0·001) than summer, except in 2003. Total non‐structural carbohydrate (TNC) content was greater (P < 0·05) in spring than in summer, except in 2004. Animal performance was superior in spring versus summer (P < 0·001). Animal plasma urea nitrogen (PUN) was lower (P < 0·05) for OP in 2003. When PUN was correlated with nutritive value indicators, the ratio of TNC to crude protein (CP) had the strongest correlation. The strong correlation indicates the need for synchronized ruminal energy and CP availability. Development of silvopasture from existing woodlots has potential to improve whole farm productivity on marginal lands.  相似文献   

5.
The redistribution of herbage production during the growing season to synchronize herbage supply with feed demand by livestock by altering the application pattern of a range of nitrogen (N) fertilizer rates was studied. Application rates of N were 50, 150 and 250 kg N ha?1 per annum and patterns were with 0·60 of N fertilizer applied before June (treatment RN) and with only 0·20 of N fertilizer before June (treatment IN). Treatments were imposed in a cutting (simulated grazing) experiment (Experiment 1), which was conducted for 2 years and a grazing experiment (Experiment 2) which was conducted for 3 years. In both experiments, herbage production was reduced in April and May and increased in the June–October period on treatment IN relative to RN, but annual herbage production was not significantly affected except in the third year of Experiment 2, when treatment RN had significantly (P < 0·05) higher herbage production than treatment IN. Crude protein (CP) concentration of herbage was lower in April and May on treatment IN than treatment RN. However, CP concentration of herbage was rarely below 150 g kg?1 DM and so it is unlikely that livestock productivity would be compromised. On treatment IN, concentrations of CP in herbage were higher in the late summer than on treatment RN, which may increase livestock productivity during July and August when livestock productivity is often lower. Altering the strategy of application of N fertilizer did not affect in vitro dry matter digestibility of herbage.  相似文献   

6.
The effects of allowance of extended (deferred) grazed herbage (AEGH) and herbage allocation management (HAM) were studied in ewe lambs (248) and late‐gestation ewes (152), respectively, on commercial farms in south‐east Ireland in 2005–06. In Experiment 1, which consisted of four treatments, the effects of AEGH (0·75, 1·25 and 1·75 kg DM per head daily) and concentrate supplementation (0·5 kg per head daily with the 0·75 kg DM herbage allowance) on lamb performance during the extended grazing (16 December to 3 March) and subsequent grazing (4 March to 11 August) seasons were evaluated. Increasing AEGH increased herbage intake linearly (P < 0·001) and live weight (P < 0·001) at the end of extended grazing and the subsequent grazing season. In Experiment 2, single‐ and twin‐bearing ewes were allocated to either a conventional (single‐ and twin‐bearing ewes grazed separately) or leader–follower system (twin‐ and single‐bearing ewes, as leaders and followers respectively) of HAM from 30 January to 24 March. The same quantities of herbage were offered daily for each system. System of HAM affected ewe condition score at lambing but did not alter (P > 0·05) subsequent lamb birth or weaning weights. It is concluded that increasing AEGH to ewe lambs increased liveweight gain during extended grazing and resulted in heavier animals in mid August of the subsequent grazing season. For ewe lambs each 1 kg concentrate DM had the same feed value as 2·4 kg DM AEGH. Use of a leader–follower system for ewes in late pregnancy did not alter lamb birth weight or subsequent performance.  相似文献   

7.
The benefits of white clover (Trifolium repens L.) in pastures are widely recognized. However, white clover is perceived as being unreliable due to its typically low content and spatial and temporal variability in mixed (grass‐legume) pastures. One solution to increase the clover proportion and quality of herbage available to grazing animals may be to spatially separate clover from grass within the same field. In a field experiment, perennial ryegrass (Lolium perenne L.) and white clover were sown as a mixture and compared with alternating strips of ryegrass and clover (at 1·5 and 3 m widths), or in adjacent monocultures (strips of 18 m width within a 36‐m‐wide field). Pastures were stocked by ewes and lambs for three 10‐month grazing periods. Over the 3 years of the experiment, spatial separation of grass and clover, compared with a grass–clover mixture, increased clover herbage production, although its proportion in the sward declined through time (0·49–0·54 vs 0·34 in the mixture in the first year, 0·28–0·33 vs 0·15 in the second year and 0·03–0·18 vs 0·01 in the third year). Total herbage production in the growing season in the spatially separated treatments decreased from 11384 kg DM ha?1 in the first year to 8150 kg DM ha?1 in the third year. Crude protein concentration of clover and grass components in the 18‐m adjacent monoculture treatment was greater than the mixture treatment for both clover (310 vs 280 g kg?1 DM) and grass (200 vs 180 g kg?1 DM). There was no clear benefit in liveweight gain beyond the first year in response to spatially separating grass and clover into monocultures within the same field.  相似文献   

8.
Growth of grass herbage in Ireland is highly seasonal with little or no net growth from November to February. As a result, feed demand exceeds grass supply during late autumn, winter and early spring. At low stocking rates [≤2 livestock units (LU) ha?1], there is potential to defer some of the herbage grown in autumn to support winter grazing. This study examined the effects of four autumn‐closing dates and four winter‐grazing dates in successive years on the accumulation of herbage mass and on tiller density in winter and subsequent herbage production at two sites in Ireland, one in the south and one in the north‐east. Closing swards from grazing in early and mid‐September (north‐east and south of Ireland respectively) provided swards with >2 t DM ha?1 and a proportion of green leaf >0·65–0·70 of the herbage mass above 4 cm, with a crude protein (CP) concentration of >230 g kg?1 DM and dry matter digestibility (DMD) of >0·700. The effects of autumn‐closing date and winter‐grazing date on herbage production in the subsequent year varied between the two sites. There was no significant effect of autumn‐closing date in the north‐eastern site whereas in the south earlier autumn closing reduced the herbage mass in late March by up to 0·34 t DM ha?1 and delaying winter grazing reduced the herbage mass in late March by up to 0·85 t DM ha?1. The effects of later grazing dates in winter on herbage mass continued into the summer at the southern site, reducing the herbage mass for the period from late March to July by up to 2 t DM ha?1. The effects of imposing treatments in successive years did not follow a consistent pattern and year‐to‐year variation was most likely linked to meteorological conditions.  相似文献   

9.
The use of imaging spectroscopy to predict the herbage mass of dry matter (DM), DM content of herbage and crude fibre, ash, total sugars and mineral (N, P, K, S, Ca, Mg, Mn, Zn and Fe) concentrations was evaluated. The experimental system used measured reflectance between 404 and 1650 nm at high spatial (0·28–1·45 mm2) and spectral resolution. Data from two experiments with Lolium perenne L. mini‐swards were used where the degree of sward damage or N‐fertilizer application varied. Regression models were calibrated and validated and the potential reduction in prediction error with multiple observations was estimated. The mean prediction errors for DM mass, DM content and N, total sugars, ash and crude fibre concentrations were 235–268 kg ha?1, 9·6–16·8 g kg?1, 2·4–3·4 g kg DM?1, 16·2–27·7 g kg DM?1, 5·8–6·5 g kg DM?1 and 8·4–10·4 g kg DM?1 respectively. The predictions for concentrations of P, K, S and Mg allowed identification of deficiency levels, in contrast to the concentrations of Na, Zn, Mn and Ca which could not be predicted with adequate precision. Prediction errors of DM mass may be maximally reduced to 95–142 kg ha?1 with 25 replicate measurements per field. It is concluded that imaging spectroscopy can provide an accurate means for assessment of DM mass of standing grass herbage. Predictions of macronutrient content and feeding value were satisfactory. The methodology requires further evaluation under field conditions.  相似文献   

10.
The provision of grass for early spring grazing in Ireland is critical for spring calving grass‐based milk production systems. This experiment investigated the effect of a range of autumn closing dates (CD), on herbage mass (kg DM ha?1), leaf area index (LAI) and tiller density (m?2) during winter and early spring. Thirty‐six grazing paddocks, closed from 23 September to 1 December 2007, were grouped to create five mean CD treatments – 29 September, 13 October, 27 October, 10 November, 24 November. Herbage mass, tiller density and LAI were measured every 3 weeks from 28 November 2007 to 20 February 2008; additionally, herbage mass was measured prior to initial spring grazing and tiller density was measured intermittently until September 2008. Delaying CD until November significantly (P < 0·05) reduced herbage mass (by approximately 500 kg DM ha?1) and LAI (by approximately 0·86 units) in mid‐February. On average, 35% of herbage mass present on swards on 20 February was grown between 28 November and 30 January. LAI was positively correlated with herbage mass (R2 = 0·78). Herbage mass increased by approximately 1000 kg DM ha?1 as spring grazing was delayed from February to April. Tiller density increased from November to February, although it did fluctuate, and it was greatest in April (9930 m?2). This experiment concludes that in the south of Ireland adequate herbage mass for grazing in early spring can be achieved by delaying closing to early mid‐October; swards required for grazing after mid‐March can be closed during November.  相似文献   

11.
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   

12.
Warm‐season pasture residue may create problems for no‐till overseeding with cool‐season grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above‐surface residues of warm‐season pasture averaging 1·62, 2·48 or 3·36 t DM ha?1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no‐till drilling into dormant warm‐season pasture. On average, no‐till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool‐season grass production was increased by 0·16 when no‐till drilled, but combined yearly total herbage production of cool‐ and warm‐season grasses was increased by 0·07 when cool‐season grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of cool‐season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over‐winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm‐season pasture residue in autumn.  相似文献   

13.
Sloping fields on soils of shallow depth to tillage are commonly left uncultivated in many parts of the world. This study was conducted to compare the effects on morphological traits, dry‐matter (DM) yield, legume ratio (LR), crude protein content (CP), crude protein yield (CP yield) and mineral concentrations (N, P, K, S, Ca, Cu, Fe, Mg, Mn, Na, B and Zn) of Hungarian vetch (Vicia pannonica Crantz.) and barley (Hordeum vulgare L.) grown in intercropping mixtures in response to three rates of organic solid cattle manure application (M0: 0, M1: 10, M2: 20 t ha?1). Experimentation was conducted on soils of two different soil depths [shallow (8–12 cm; low‐medium erosion risk) and normal soil depth (18–22 cm; no erosion risk)] on a sloping field in the 2006–2007 and 2007–2008 growing seasons at Gumushane, Turkey. Herbage harvested on the shallow depth area had 22–73% less DM yield, 14–72% less CP yield, 6–9% greater CP content and generally higher minerals contents than herbage from the normal soil depth area. Cattle manure applications increased DM yield by about 23%, increased CP content and CP yield, and also increased the contents of most minerals in herbage of the intercropping mixtures, relative to the control, averaged over the two soil depths. It is suggested that, for areas with shallow soil depths that are prone to erosion, plant cover should be used for forage production, and that fertilization with solid cattle manure at 20 t ha?1 can support production of quality forage of acceptable DM yield.  相似文献   

14.
Five pastures in an Mediterranean environment in southern Italy were fertilized for 6 years (1993–1998) with nitrogen (N) fertilizer, phosphorus (P) fertilizer and two levels low (L) and high (H) of combined nitrogen and phosphorus fertilizer (N‐P), and compared with a no‐fertilizer control treatment, and the effects on soil variables, dry matter (DM) yield of herbage and floristic composition of the pastures measured. From 1998–2002, half of each plot was fertilized with the same treatments (continued treatment) while the other half received no fertilizer (discontinued treatment). In the year 2001–2002, the plots on the discontinued fertilizer treatments and the plots on the control treatment were used to evaluate the residual effects of the fertilizer treatments. The P and N‐P fertilizer continued and discontinued treatments, in comparison to the control treatment, had a higher content of available P2O5 in the soil while under the N fertilizer treatment it decreased. The N and P fertilizer treatments and the residual effects of these treatments led to higher DM yields and proportions of Gramineae and Leguminosae, respectively, compared to the control treatment. Furthermore, differences in the nutritive value of the herbage and floristic composition were observed between the N‐P fertilizer treatments and the control treatment. The residual effect of the N, P and N‐P fertilizer treatments increased DM yield proportionately by 0.063, 0.385 and 0.404, respectively, and reduced the crude protein content of the herbage. The residual effects of the fertilizer treatments on milk forage units (MFU) were 261 for N, 1107 for P and 1003 MFU ha?1 for N–P fertilizer treatments. Among fertilizers, the residual effect of the N‐P fertilizer treatment promoted an increase in DM yield but produced little variation in floristic composition of the pasture. In general, the fertilizer treatments increased DM yield and nutritive value of herbage and reduced floristic composition in pastures on these Mediterranean sites.  相似文献   

15.
Abstract A glasshouse study was undertaken to determine the physiological and morphological changes in cocksfoot (Dactylis glomerata L.) during regrowth after defoliation. Individual plants were arranged in a mini‐sward in a randomized complete block design. Treatments involved harvesting each time one new leaf had expanded (one‐leaf stage), up to the six‐leaf stage, with the plants separated into leaf, stubble (tiller bases) and roots. Stubble and root water‐soluble carbohydrate (WSC), stubble and leaf dry matter (DM), tiller number per plant and leaf quality (crude protein (CP), estimated metabolizable energy (ME) and mineral content) were measured to develop optimal defoliation management of cocksfoot‐based pastures. WSC concentration in stubble and roots was highest at the five‐ and six‐leaf stages. Mean WSC concentration (g kg?1 DM) was greater in stubble than roots (32·7 ± 5·9 vs. 9·4 ± 1·5 respectively). There was a strong positive linear relationship between plant WSC concentration and leaf DM, root DM and tillers per plant after defoliation (Adj R2 = 0·72, 0·88 and 0·95 respectively). Root DM plant?1 and tiller DM tiller?1 decreased immediately following defoliation and remained low until the three‐leaf stage, then increased from the four‐leaf stage. Tillers per plant remained stable until the four‐leaf stage, after which they increased (from 9·9 ± 0·5 to 15·7 ± 1·0 tillers plant?1). Estimated metabolizable energy concentration (MJ kg?1 DM) was significantly lower at the six‐leaf stage (11·01 ± 0·06) than at any previous leaf regrowth stage, whereas CP concentration (g kg?1 DM) decreased with regrowth to the six‐leaf stage. Both the levels of ME and CP concentrations were indicative of a high quality forage throughout regrowth (11·37 ± 0·04 and 279 ± 8·0 for ME and CP respectively). Results from this study give a basis for determining appropriate criteria for grazing cocksfoot‐based pastures. The optimal defoliation interval for cocksfoot appears to be between the four‐ and five‐leaf stages of regrowth. Delaying defoliation to the four‐leaf stage allows time for replenishment of WSC reserves, resumption of root growth and an increase in tillering, and is before herbage is lost and quality falls due to onset of leaf senescence.  相似文献   

16.
This study investigated the effects of levels of supplementation with maize grain and herbage allowance (HA) on grass herbage and maize intake, animal performance and grazing behaviour in two replicated grazing experiments with Angus beef cattle in Argentina. In Experiment 1, the response to increasing HA (2·5, 5·0 and 7·5 kg DM herbage 100 kg?1 live weight (LW) d?1 with and without 0·5 kg DM maize grain 100 kg?1 LW d?1) was investigated. In Experiment 2, the responses to level of maize grain offered (0, 0·5 and 1·0 kg DM maize grain 100 kg?1 LW d?1) at an HA of 2·5 kg DM herbage 100 kg?1 LW d?1 and an HA of 5·0 kg 100 kg?1 LW d?1 without maize grain were assessed. In Experiment 2, soyabean meal was added to control the crude protein concentration in the diet. Two methods were used for intake estimations: pre‐ and post‐feeding herbage mass difference, and the use of the n‐alkane and 13C technique. The latter predicted most accurately the metabolizable energy requirements calculated from live weights and liveweight gain of beef cattle attained in each treatment in both experiments. Increasing HA significantly increased herbage intake and liveweight gain (P < 0·01), and general quadratic relationships between these variables could be fitted across experiments despite differences in animal and pasture characteristics. Increasing the amount of maize grain offered significantly reduced herbage intake and grazing time, but increased liveweight gain and digestibility of the diet. Substitution rate increased with increasing HA in Experiment 1 but was not affected by level of maize supplementation in Experiment 2. These relationships will aid the development of grazing management models for Argentinean conditions.  相似文献   

17.
A perennial ryegrass (Lolium perenne L.)‐dominated sward on a well‐drained soil (Experiment 1) and a creeping bent (Agrostis stolonifera L.)‐dominated sward on a poorly drained soil (Experiment 2) were subjected to four treading treatments: control (C, no damage), light damage (L), moderate damage (M) or severe damage (S) to quantify the effects on herbage dry‐matter (DM) production and tiller density. In Experiment 1, treading damage was imposed in spring. In Experiment 2, one‐third of the site was damaged in autumn, one‐third in spring and one‐third in both spring and autumn. Both sites were rotationally grazed after treading treatments. Pre‐grazing herbage mass was measured eight times in Experiment 1 and seven times in Experiment 2 on each plot, and tiller density was assessed four times in each experiment. In Experiment 1, pre‐grazing herbage mass was reduced by 30% in S plots at the first harvest after damage, but cumulative pre‐grazing herbage DM production was not different between treatments (12·7 t DM ha?1). In Experiment 2, annual cumulative pre‐grazing herbage mass was reduced by between 14 and 49%, depending on intensity of treading damage event and season when damage occurred. Tiller density was not affected by treatment in either experiment. A perennial ryegrass‐dominated sward on a well‐drained soil was resilient to heavy treading damage. A creeping bent‐dominated sward on poorly drained soil requires a more careful grazing management approach to avoid major losses in cumulative pre‐grazing herbage mass production during wet weather grazing events.  相似文献   

18.
The objective of this study was to examine the effect of herbage mass and daily herbage allowance (DHA) on sward characteristics and animal performance, dry‐matter intake, rumen pH and volatile fatty acid production of unsupplemented spring‐calving dairy cows throughout the main grazing season. Sixty‐eight Holstein‐Friesian dairy cows were randomly assigned across four treatments (n = 17) in a 2 × 2 factorial design. Two swards were created with different levels of pre‐grazing herbage mass [allocated above 4 cm (>4 cm); 1700 kg DM ha?1 (medium; M) or 2200 kg DM ha?1 (high; H)] and two levels of DHA (>4 cm; 16 or 20 kg DM per cow d?1). An additional eight lactating ruminally cannulated Holstein–Friesian dairy cows were randomly assigned to each treatment in a replicated 4 × 4 Latin square design. Sward and animal measurements were collected across four periods each of 1 week duration in April and May (PI) and July and August (PII). Maintaining the medium‐mass sward across the season improved the nutritive value of the sward in the latter part of the grazing season compared with high‐mass swards, thus resulting in increased animal intakes and milk production throughout PII. The higher organic matter digestibility of the medium‐compared with high‐masses during PII indicates that grazing severity and herbage mass in the spring to mid‐summer period will determine sward quality parameters in the late summer period.  相似文献   

19.
In Appalachian USA, silvopasture offers promise of increased farm productivity. A synchronized, temporal understanding of open pasture (OP) and silvopasture (SP) nutritive characteristics is essential for grazing system development. We examined pasture‐type nutritive‐value relationships when herbage was harvested based on morphological maturity rather than calendar date. Neutral detergent fibre and acid detergent fibre (ADF and NDF) content were greater in silvopasture, while organic matter (OM) was lower (P < 0·05). Digestibility of SP herbage dry matter (DM) and OM tended (P = 0·10) to be lower (418 vs. 471 and 437 vs. 491 g kg?1 respectively). Neutral detergent fibre digestibility was greater (P < 0·05) for OP than SP forage (538 vs. 480 g kg?1), and ADF tended to be greater (P = 0·10; 551 vs. 501). Open‐pasture forage fermentation effluent exhibited slightly higher microbial richness and Shannon diversity than SP. However, overall community composition of both bacteria and archaea did not differ between pasture types or sampling times. Pasture types show proximate analyses differences generally favourable to OP, although both have similar overall nutritive value. In addition, the SP sward exhibited a 4‐ to 6‐days delay in reaching equivalent maturity. Conversion of farm woodlots to SP would increase overall herbage production and improve pasture management flexibility.  相似文献   

20.
The effects on the performance of dairy cows offered kale, swedes, and perennial ryegrass in situ and perennial ryegrass silage fed indoors to dairy cows pre‐partum during winter in Ireland was examined. Eighty‐eight spring‐calving dairy cows were randomly assigned to one of four offered treatments; (i) 8 kg of dry matter (DM) of kale leaf and stem + 4 kg DM of perennial ryegrass silage (treatment K), (ii) 8 kg DM of the root and leaf of swedes + 4 kg DM of perennial ryegrass silage (treatment S), (iii) 12 kg DM of perennial ryegrass herbage (treatment G) offered in situ and (iv) perennial ryegrass silage offered ad libitum indoors (treatment ID). Cows on treatments K, S and ID had a greater (P < 0·001) increase in body condition score (0·20, 0·14 and 0·50 units respectively) pre‐partum than cows on treatment G which lost 0·22 units. Pre‐partum treatment had no effect on variables of milk production in the following lactation. In the first 100 d of lactation, cows on treatment G pre‐partum had a lower milk fat concentration (35·6 g kg?1) compared with cows on treatments S and ID (38·3 and 39·3 g kg?1 respectively). There was no effect of treatment on the intervals between parturition and first insemination (mean 74·6 d) and conception (mean 96·1 d). The results suggest that offering kale and swedes to dairy cows pre‐partum resulted in a similar lactation performance to dairy cows grazing a perennial ryegrass sward or offered perennial ryegrass silage indoors.  相似文献   

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