bluuebunny/crossref_metadata_2025_split huggingface dataset:
Turnover of grass laminae and white clover leaves in mixed swards continuously grazed with steers at a high‐and low‐N fertilizer level
Authors: LAIDLAW A. S. , STEEN R. W. J. 
Published: April 2006

AbstractTurnover rates of grass laminae and clover leaf tissue were estimated over a range of intervals within three periods each year in the second to fourth years (1983‐85) of a trial involving swards continuously grazed by steers and receiving either 60 kg N ha‐1 in spring (60N) or 360 kg N ha−1 throughout the year (360N). Within the 60N swards initial stocking rates at turnout were low (60N LS) at 7‐2 steers ha−1 and high (60N HS) at 90 steers ha−1 in 1983, and in 1984 and 1985 corresponding rates were 10‐8 and 13‐5 ha−1. The 360N swards were initially stocked at turnout at 96 (360N LS) and 120 (360N HS) steers ha−1. Stocking rates were reduced by 33% in midsummer except for 60N in 1984 and 1985 when they were reduced by 50%.Meaned over 3 years, 360N HS had lower herbage mass than 60N LS. Tiller density in 360N was almost 50% higher than in 60N and clover growing point density was only one quarter that of 60N with the 60N LS having lower clover densities than 60N HS in 1985.Generally, leaf extension rate per tiller was higher in 360N than 60N and, when significant, 60N LS had higher senescence rates per tiller than 360N HS.Rate of increase in new clover lamina tissue per stolon was not affected by treatments, whereas in 1983 LS had higher senescence rates of clover laminae than HS. Petiole growth per stolon was higher in LS than HS in 1983 and 1984, the mean over these years for 360N HS being 77% that of 60N LS. Petiole senescence per stolon was lower in 360N HS than 60N LS only in 1983.When comparing 60N HS and 360N LS (representing similar levels of grazing intensity, having similar herbage mass) the gross growth of leaf material in the former was 75% of the latter, in contrast to 57% for net growth. Clover contributed 18% to the estimated growth of leaves compared to a mean of 7% in herbage mass. Taking inflorescence and pseudostem into account in 1984 and 1985,60N HS had 7% clover in standing herbage and 14% in net growth. Therefore, the contribution of clover to growth is considerably higher than its presence in herbage mass would suggest in continuously grazed swards. It is concluded that low‐N swards, owing to their lower tiller density and slower grass leaf extension rate, will be less efficiently grazed than swards at higher N levels at a given herbage mass, but the presence of clover will partly offset that disadvantage.
Effects of sward surface height on the performance of continuously stocked spring‐calving beef cows and their calves
Authors: WRIGHTand I. A. , WHYTE T. K. 
Published: April 2006

AbstractThe response of continuously stocked spring‐calving beef cows and calves to a range of sward surface heights was determined. Mean sward heights of 4‐5, 60, 70, 91 and 11‐0 cm (treatments A to E respectively) were maintained from mid‐May to mid‐August (Period 1) and treatments C, D and E continued until the end of September (Period 2), during which time mean sward heights were 5‐4, 7‐8 and 9‐2 cm respectively. Hereford x Friesian or White Shorthorn‐x Galloway cows with their Charolais‐cross calves were used, with 9, 6, 6, 5 and 9 cows on treatments A to E respectively. During Period 1 the mean live weight gains of cows were‐0‐52,‐005,0‐32,075 and 0 40 (s.e.d. 0167) kg d−1 on treatments A to E respectively and during Period 2.‐0‐31, 057 and 059 (s.e.d. 0153) kg d−1 for treatments C, D and E respectively with maximum cow liveweight gain at sward heights of 8 to 10 cm. Calf liveweight gains were 0 88,091, 098, 1 04 and 1‐06 (s.e.d. 0068) kg d−1 in Period 1 for treatments A to E respectively and 098, 1‐22 and 1 35 (s.e.d. 0067) kg d−1 in Period 2 for treatments C, D and E. The percentage of area infrequently grazed was generally less than 20% on treatments A to D, but on treatment E it was more than 40% for 6 weeks after turnout and thereafter remained between 20 and 40%. Maximum calf liveweight gain per hectare was achieved on the shorter swards, but maximum total liveweight gain of cows and calves per hectare occurred on treatment D. It is concluded that for maximum cow and calf performance on continuously stocked pastures, sward height should be maintained at no more than 8 cm in spring and early summer and then increased to 9 to 10 cm later in the grazing season.
The prediction of the in vivodigestibility of the diet of sheep and cattle grazing indigenous hill plant communities by in vitrodigestion, faecal nitrogen concentration or indigestible' acid‐detergent fibre
Authors: ARMSTRONG R. H. , COMMON T. G. , DAVIES G. J. 
Published: April 2006

AbstractHerbage and faeces samples were retained from an intake and in vivodigestibility trial using material harvested at three different stages from five indigenous hill plant communities (those dominated by Agrostis‐Festuca., Nardus stricta., Molinia caerulea., Eriophorum vaginatum and Tri‐chophorum caespitosum) and from sown swards of ryegrass or white clover. Samples of the herbages and of their separate components, together with extrusa samples of the same herbages recovered from pen‐fed sheep and cattle oesophageal fistulates, were digested in vitrousing rumen liquor. Measurements were made also of faecal nitrogen concentration (FN) and of indigestible acid‐detergent fibre (IADF) using the samples from the original trial.The range of in vitrodisappearance values of the herbages (IVOMD; 0809‐0278) was slightly wider than those of in vivodigestibility (OMD; 0‐796‐0‐37I). Differences between OMD and IVOMD were greatest at low quality and relationships were best described by two separate linear regressions of OMD on IVOMD for (a) ryegrass, white clover, Agrostis‐Festucaand Nardus(RSD; 0 0185) and, (b) Molinia, Tricho‐phorumand Eriophorum(RSD; 00246). In vitrodisappearance values of extrusa were higher than those of herbages offered by 00503 and 00156 units for sheep and cattle respectively, partly because of greater levels of ensalivation, especially in the sheep. The relationships of OMD to IADF and to FN were poor, though inclusion of faeces output and fitting parallel lines for communities in the regression of OMD on FN reduced the RSD to 0020. We conclude that in vitrodigestion of samples of extrusa, using appropriate standards, is the best method of diet digestibility prediction for sheep and cattle grazing these communities.
The impact of grazing severity on perennial ryegrass/white clover swards stocked continuously with beef cattle
Authors: GIBB M. J. , BAKER R. D. , SAYER ANNA M. E. 
Published: April 2006

AbstractAn experiment was carried out to examine the changes in perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) populations in mixed swards, under different grazing severities over three successive grazing seasons. In year 1, three paddocks were erected on a sward with a low initial content of clover (block 1). Sward heights were measured using a rising‐plate meter, and were maintained at overall mean heights of 3·0, 5·5 or 7·0 cm by variable stocking with 8‐month‐old steers. In year 2, a further three paddocks were erected on an adjacent area with a high initial content of clover (block 2), and were maintained at the same three heights by similar management. Botanical analyses were carded out on samples collected at four times during the season. Maintaining swards at 5·5 or 7·0 cm led to a large proportion of the area being infrequently grazed. Block I paddocks had higher initial tiller densities, which increased as sward height was reduced, while block 2 paddocks, with their lower initial tiller density, showed little effect of sward height on tiller density. Initially, clover stolon growing‐point densities and stolon masses increased more rapidly in the taller swards. Later, however, large losses in the clover populations occurred on all paddocks during long wet winters and there was a general reversal in these trends for stolon growing‐point densities and stolon masses, 3·0>5·5>7·0. By year 3, swards with differing
Ingestive behaviour of beef cattle offered different forms of lucerne (Medicago sativa L.)†
Authors: DOUGHERTY C. T. , BRADLEY N. W. , CORNELIUS P. L. , LAURIAULT L. M. 
Published: April 2006

AbstractA change‐over design was used to establish the ingestive behaviour of twelve adult Angus cows (Bos taurus), live weight (LW) of 475 ± 18 kg, while grazing luceme (Medicago sativa L.) (T1), eating from a swath of freshly cut lucerne (T2), or eating wilted lucerne from a swath (T3). In the first experiment, the herbage dry matter (DM) allowance was 4‐7 kg h−1 and in T1 the available herbage DM mass (>5 cm) was 2892 kg ha−1. Herbage DM intake was 2.5, 1.6 and 2.0 kg h−1 (0.53,0.35 and 0.41 kg (100 kg LW)−1h−1) for T1, T2 and T3, respectively. Cattle grazed at 29 bites min−1 and ate the swathed lucerne at 6 bites min−1. Herbage DM intake per bite was 1‐2, 4‐9 and 6‐7 (2‐5,104 and 14‐4 mg(kg LW)−1)for T1, T2 and T3, respectively. The DM content of the luceme was 227, 263 and 309 g kg−1 for the same sequence. In a second experiment with luceme of available herbage DM mass of 5321 kg ha−1 and an allowance of 7‐ 3 kg h−1 cows grazed lucerne at 2‐9 kg h−1, ate freshly cut material at 21 kg h−1 and wilted herbage at 25 kg h−1 (0.61, 0.45 and 0.52 kg (100 kg LW)−1h−1), respectively. Leaf accounted for 80%, 68% and 54% of intake for T1, T2 and T3, respectively. Swathing lucerne reduced the diet selectivity by forcing cattle to take large bites that required many jaw movements to form a bolus that could be swallowed. It appeared that the mechanics of bolus formation determined ingestive behaviour of cattle eating swathed herbage.
Prevalence of Listeria species as related to chemical quality of farm‐ensiled grass
Authors: HUSU J. R. , SIVELÄ S. K. , RAURAMAA A. L. 
Published: April 2006

AbstractThe occurrence of Listeria spp. in pasture grass and grass silage made with various additives and preservation techniques is reported. Silage samples were collected three times (in November, February and May) from eighty dairy farms. The prevalence of Listeria spp. in pasture grass samples was 0.647 and in silage samples 0.227. Only two species, L. monocytogenes and L. innocua were observed. Listeria spp. Were isolated from the silage at least once at thirtynine farms (0.488), and L. monocytogenes at twenty‐seven farms (0.338). The occurrence of Listeria was highest among the silage samples collected in November (0.288). Silages preserved with acids had the lowest prevalence of Listeria (0.194). Silages preserved in tower silos were most often free of Listeria, only 0.056 being positive. The highest prevalence of the Listeria spp. (0.324) was detected in clamp silage. The results of chemical analyses of silage statistically reflect the frequency of Listeria.
Growth, colonization and productivity of two white clover cultivars strip‐seeded into an upland Festuca‐Agrostis sward
Authors: WILLIAMS E. D. , HAYES M. J. 
Published: April 2006

AbstractSmall plots of a Festuca‐Agrostis upland sward on a peaty gley podsol were strip‐seeded during late June 1986 with white clover cvs Aberystwyth S184 or Menna at 4 kg ha−1 and defoliated early (20 August) or late (3 September) and then frequently or infrequently (every 2 weeks or 4 weeks) until the end of September. All plots were defoliated in early November, at 3‐weekly intervals during the growing season in 1987 and then grazed rotationally during 1988.Satisfactory seedling establishment, representing 46% emergence, was achieved 5 weeks after sowing. The differential defoliation regimes had no persistent significant effects on clover development. S184 soon produced more leaves per seedling than Menna and a smaller proportion of its leaf number and weight were removed at each defoliation. Following large losses of leaves over the 1986–87 winter, SI84 had significantly more leaves per stolon than Menna; subsequently it also colonized the sward at a quicker rate. During 1987 amounts of herbage harvested (6.1 t ha−1) were similar with the two clover cultivars, with S184 contributing 47% and Menna 44% of this respectively. SI84 made a larger contribution to yield during May and June but Menna was more productive during September and October. During 1988 clover populations were maintained with rotational grazing without additional fertilizer inputs.The results show that, despite initial soil and climatic contraints, both small and medium‐leaved clovers can be strip‐seeded into upland swards with large subsequent benefits to yield and herbage quality. However, they also indicate the need for further experiments to determine the influence of sward morphology and defoliation regime on stolon branching rates and accumulation of growing points which, in turn, govern sward colonization.
Productivity of prairie grass (Bromus willdenowii Kunth) affected by sowing date and the head smut fungus (Ustilago bullata Berk.)
Authors: FALLOON R. E. , ROLSTON M. P. 
Published: April 2006

AbstractEffects of sowing date, fungicide seed treatments, and the head smut fungus Ustilago bullata Berk, on establishment, herbage, and seed production of prairie grass cv. Grasslands Matua (Bromus willdenowii Kunth) were measured in autumn‐ and spring‐sown field trials in New Zealand.Autumn seedling establishment from thiram‐treated seed relative to untreated seed was increased by 27% from the earliest sowing (early March), and by 65% from the latest sowing 8 weeks later. Infestation of seed with ustilospores of U. bullata reduced seedling establishment at all but the latest autumn sowing. Fungicide seed treatments had little effect on spring seedling establishment, but V. bullata infestation of seed reduced establishment compared with healthy seed, particularly after late sowings (early November).Herbage production was greater from early than from late sowings in both autumn and spring, and was less in plants grown from U. bullata infested seed than in plants from healthy seed. Enhanced autumn establishment from thiram‐treated seed led to improved herbage production when plants were young, but this effect disappeared about 18 weeks after late autumn sowing. Overall herbage production from spring sowing was more than twice that from autumn sowing.A 6‐week delay in autumn sowing led to a 58% reduction in seed production the following summer.Early autumn and spring sowings, together with adequate control of seedling diseases, are likely to give optimum herbage and seed production from prairie grass.
Short‐term effects of nitrogen on the growth and nitrogen nutrition of small swards of white clover and perennial ryegrass in spring
Authors: DAVIDSON I. A. , AFRC M. J. ROBSON 
Published: April 2006

AbstractSmall swards of white clover and perennial ryegrass were established in Perlite in a heated glasshouse, as either monocultures or mixtures of equal plant numbers. On 26th March, 1984 the swards were moved outside and their growth studied over the period to 29th May. All swards received a basal level of nitrate N to simulate soil mineralization and two‐thirds received additionally the equivalent of 80 kg N ha−1. Over the experimental period (26th March‐29th May) clover maintained its proportion of total mixture dry weight In swards given ‘fertilizer’‐N and increased its proportion in those given only ‘basal’ N, However, clover declined as a percentage of total mixture dry weight during the first period of the experiment when total leaf area index (LAI) and ambient temperatures were low, and increased its percentage later when temperature and LAI had risen. Changes in tiller and stolon growing point numbers were not good indicators of changes in dry weight. Relative yields and relative replacement rates also were not good indicators of relative performance in mixture. Where ‘fertilizer’‐N was applied, clover derived less of its nitrogen from that source than grass although their uptakes per unit shoot dry weight were similar.
Effect of fertilizer nitrogen source and cattle slurry on herbage production and nitrogen utilization
Authors: LONG F. N. J. , GRACEY H. L 
Published: April 2006

AbstractA field plot experiment was carried out on an established grassland sward from 1983–88 inclusive to examine the effects of time of application, chemical form of nitrogen (N) and cattle slurry dry matter (DM) content on yield and efficiency of N use. Four forms of fertilizer N (a semi‐organic fertilizer, a combined 2.1:1 (w/w) semi‐organic/calcium ammonium nitrate (CAN) fertilizer, CAN and urea, each supplying 300 kg N ha−1 year−1, were applied with or without unseparated or separated cattle slurry at 93 and 73 g kg−1 DM respectively, both supplying approximately 150 kg N ha−1 year−1. All fertilizers and slurries were applied in three equal dressings (February/March, May/June and July/August). The efficiency of use of fertilizer and slurry N was evaluated by measuring DM yield, N uptake and apparent recovery of N in herbage at all harvests during each growing season.Fertilizer N application significantly increased (P<0.001) the mean yields of herbage at each harvest in all years. The form of fertilizer N had no significant effect (P>0.05) on first harvest and total herbage yields, nor on N uptakes by herbage at the first harvest in any year. The performance of urea and of CAN was more variable at the second and third harvests relative to that of the semi‐organic or combined 2.2:1 (w/w) semi‐organic/CAN sources which had similar efficiencies of N use. Lower DM production was associated with reduced uptake of N. Values for mean overall apparent recovery of N ranged from 57.9 ± 2.67% for the semi‐organic fertilizer to 50.2±3.05% for CAN.Unseparated cattle slurry and separated cattle slurry produced similar herbage yields and N responses that were lower and more variable than with fertilizer N. The overall mean apparent recovery of N from unseparated cattle slurry was 25.5 ± 5.03% compared to 5.0 ± 4.74% for separated cattle slurry. Efficiency of N use was highest with spring applications and least with mid‐season applications. Recoveries ranged from −29% for separated cattle slurry applied in June 1984 to 56% for unseparated and separated cattle slurry applied in February 1988 and June 1987 respectively. No interactions were recorded between cattle slurry and fertilizer N in terms of DM production or N uptake by herbage.The results of this study support the use of a fertilizer N source, selected on a least‐cost basis, in combination with slurry to promote spring herbage production. For subsequent production, N should be supplied in fertilizer form only. The use of urea is risky under low rainfall conditions. Mechanical separation did not improve the efficiency of use of slurry N.
Effects of an established sward of Lolium perenne L. on the growth and development of Rumex obtusifolius L. seedlings
Authors: JEANGROS B. , NÖSBERGER J. 
Published: April 2006

AbstractSeedlings of Rumex obtusifolius L. were grown in gaps (11 cm diameter) in an established sward at Lolium perenne L., Root competition from the surrounding sward was controlled by PVC tubes and shoot competition was controlled by cutting the sward frequently. All combinations, with and without root competition and with and without shoot competition, were used.Plants received either 40 or 80 kg N ha−1 month−1 and 0 or 300 kg K2O ha−1 and were harvested 39 d after emergence; a second harvest was made 12 d later, after shading to 20% of full sunlight.The shoot dry weight per plant of R. obtusifolius was much more affected by root competition than by shoot competition, especially at low nitrogen applications. Potassium supply had no effect.More dry matter was allocated to the leaf petioles under shaded conditions and the specific leaf area was greater. This morphological plasticity enabled R. obtusifolius to grow well under shading and to be affected only slightly by shoot competition from L. perenne.The results suggest that competition for nitrogen was the main factor limiting the initial grown of R. obtusifolius in a ryegrass sward and that the morphological characteristics of R. obtusifolius make it less susceptible to competition for light in the early stages of its development.
White clover seed production from mixed swards: effect of sheep grazing on stolon density and on seed yield components of two contrasting white clover varieties
Authors: MARSHALL A. , HIDES D. H. 
Published: April 2006

AbstractA trial was carried out over two harvest years to assess the effect of sheep grazing and closing date on stolon density and seed yield components of two contrasting white clover varieties and to determine the potential for producing clover seed from mixed swards in an integrated livestock/seed production system.Overall, the small‐leaved cv. S184 had a higher stolon density at closing and harvest than the large‐leaved cv. Olwen, but only significantly so in 1987. Stolon density at closing was generally increased by delaying closing. Varieties also differed in their response to closing date. Stolon density of cv. S184 in both harvest years, generally increased with later closing whilst cv. Olwen was less influenced by closing date and at all dates in 1987, and all but one date in 1986 was not significantly different from the ungrazed treatment.Delay of closing significantly increased stolon density at harvest on all closing dates in 1987 but had no effect in 1986. Varieties responded similarly to a delay in closing but the magnitude of increase of cv. Olwen was less than that of cv. S184.The seed yield components of both cv. S184 and cv. Olwen were influenced by closing date, but the effect differed between years. Although there was some initial increase in inflorescence production, delaying closing after inflorescence buds appeared on the stolon reduced inflorescence number of cv. Olwen in both years but reduced inflorescence number in cv. S184 in 1986 only. However, inflorescence size, seed yield per inflorescence and the proportion of ripe inflorescences at harvest was reduced in both years. Cultivar S184 produced more inflorescences than cv. Olwen in both years and in both years tolerated later closing than cv. Olwen.The effect of sheep grazing and closing date is discussed in relation to stolon removal and the suitability of particular leaf types for this system of seed production.
Herbage productivity of a range of grass species in association with white clover
Authors: FRAME J. 
Published: April 2006

AbstractRed fescue (Festuca rubra L.) cvs Reptans, Dawson and Ruby, perennial ryegrass (Lolium perenne L.) cvs Perma and Sprinter, crested dogstail (Cynosurus cristatus L.) cv. Southlands, smooth meadow‐grass (Poa pratensis L.) cvs Parade and Arena, Yorkshire fog (Holcus lanatus L.) commercial types I and II, creeping bent (Agrostis stolonifera L.) cv. Penncross and rough meadow‐grass (Poa trivialis L.) cvs Omega Øtofte, Dasas and Sabre were each sown with white clover (Trifolium repens L.) cv. Donna and the productivity of the fourteen mixtures assessed under simulated grazing (six harvests per year) for 3 years. A single fertilizer‐N rate (50 kg ha−1) in early spring was applied to all treatments each year.Over the 3 years, mean annual dry matter (DM) production of the swards ranged from 5·25 t ha−1 (creeping bent) to 8·71 t ha−1 (red fescue cv. Reptans), with the species ranking order of: red fescue > perennial ryegrass > crested dogstail > smooth meadow‐grass > Yorkshire fog > creeping bent. Rough meadow‐grass only persisted over the first harvest year. Mean annual organic matter digestibility (OMD) values of the swards ranged from 0·712 (creeping bent) to 0·782 (ryegrass cv. Sprinter). Mixtures with the lowest proportion of grass (crested dogstail and smooth meadow‐grass) generally gave the highest proportions of white clover. The creeping bent mixture had exceptionally low production of both components.Red fescue, crested dogstail and smooth meadow‐grass showed compatibility with clover and, therefore, have potential for use in grass/clover swards. Yorkshire fog had lower compatability with clover. Some breeding effort to improve selected characteristics of promising species, e.g. improvement of low OMD in red fescue, seems warranted.