bluuebunny/crossref_metadata_2025 huggingface dataset:
Fertilizer requirements for maintenance of a perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) pasture growing on a humus iron podzol in N.E. Scotland
Authors: RANGELEY ANNE
Published: April 2006

Ryegrass/white clover pastures were reseeded on heather moor in north‐cast Scotland in 1978/79. By 1981, despite moderate fertilizer applications, the pastures had deteriorated and dry matter (DM) production was low. After preliminary soil and herbage analysis an omission trial was carried out in 1982/83 at two sites (A and B) to identify the factors which limited production.

At site A depressions in growth occurred in the absence of N, P and K. Perennial ryegrass was severely N deficient with concentrations in leaves of less than 22 g N kg−1 in spring and summer even after application of 120 kg N ha−1 annually. Rates of nitrogen fixation were high in spring but rapidly declined in June and July as the soil moisture tension increased. Application of N fertilizer also reduced the N2 fixation rate. Deficiencies of F and K occurred despite apparently high levels of extractable F in the soil. Uptake of these nutrients was inhibited in the dry soil during the summer. White clover was more susceptible to drought than perennial ryegrass, probably because it rooted at a shallower depth.

Growth at site B was limited by acidity and lack of N and K. The soil pH was 4 8 (s.d. = 0middot;75) at 1‐5 cm depth. Application of 2 5 t lime ha−1 in spring 1982 had not altered the pH by autumn 1983.

It was concluded that methods of incorporating lime into the soil, together with ways of increasing the rates of N2 fixation by white clover and transfer to grass, should be investigated further. Regular small applications of N and K may be necessary to sustain DM production at the level required by the farming system.
Effects of sowing date, placement of seed, vegetation suppression, slugs, and insects upon establishment of no‐till alfalfa in orchardgrass sod†
Authors: BYERS R. A. , TEMPLETON W. C.
Published: April 2006

Four treatments designed to affect some environmental factors during germination and establishment of alfalfa were: two sowing dates (March and May) to produce differences in temperature, light and soil moisture; two sowing methods (notill drill and hand sowing) for creating different degrees of soil‐seed contact; mowing and banded and broadcast sprays of glyphosate to produce varying degrees of plant competition; and methiocarb bait combined with carbofuran granules vs. no pesticide to establish different levels of invertebrate feeding.

Alfalfa dry matter (DM) production was affected very little by sowing date in two identical experiments. It was unaffacted by sowing method in experiment 1 (1983) but was significantly higher when alfalfa was sown with a drill in the second trial (1984). Highest alfalfa DM yields were achieved when competition was suppressed by broadcast spraying rather than bands, but details of effect differed in the two experiments.

Pesticide treatments yielded more alfalfa DM in the year of establishment. Slugs, Deroceras leave (Müller) and D. reticulatum (Müller), and the potato leafhopper, Empoasca fabae (Harris), were among the potential pest species controlled and may have been partly responsible for the observed effects.
Sward maintenance of Lolium multiflorum by slurry seeding
Authors: JONES E. L. , ROBERTS J. E.
Published: April 2006

A field investigation into the effect of slurry seeding on the dry‐matter yield and persistence of an Italian ryegrass sward was assessed over a 3‐year period (1984–86) under a regime of three cuts per season combined with sheep grazing in early spring and late autumn. Results showed that slurry plus seed treatments produced up to 30% more herbage dry matter and a significantly higher tiller density than where no slurry or seed were used. Slurry application with and without seed also reduced the proportion of weed grasses (mainly Poa spp.) in the sward. It is concluded that slurry seeding is a useful technique for extending the productive life of an Italian ryegrass sward.
Nitrogen concentrations in the cell wall and lignocellulose of smooth homegrass herbage*
Authors: SANDERSON M. A. , WEDIN W. F.
Published: April 2006

Applying nitrogen (N) fertilizer to grass generally increases N concentration in herbage. Not as well documented, however, are N fertilizer effects on concentrations of N in plant cell walls and lignocellulose. The objective four study was to ascertain how N fertilizer applied with or without a nitrification inhibitor would affect N concentrations in the cell wall (neutral‐detergent fibre (NDF)) and lignocellulose (acid‐detergent fibre (ADF)) of smooth bromegrass (Bromus inermis Leyss). Nitrogen fertilizer ((NH4)2SO4) was applied at 0, 125, or 230 kg N ha−1 in combination with 0, 2–5, or 50 kg ha−1 of nitrapyrin (2‐ chloro‐6‐(trichloromethyl) pyridine) to smooth bromegrass in April of 1985 and 1986. Herbage was harvested at 2, 4, 6 and 8 weeks after treatment. Freeze‐dried herbage samples were analysed for in vitro digestible dry matter (IVDDM), total N, and N in neutral‐ and acid‐detergent fibre (NDFN and ADFN, expressed as g kg−1 NDF and ADF, respectively). Nitrapyrin had no effect on IVDDM, total N, NDFN or ADFN, Nitrogen fertilizer increased concentrations of total N in herbage dry matter, and increased N concentrations in NDF and ADF. Most of the increase in total N concentration occurred in the neutral‐detergent soluble portion. When NDFN and ADFN concentrations were expressed on a total N basis (g k g−1 of total N), N fertilizer had no effect. Available fibre N (AFN; calculated as NDFN minus ADFN, each expressed as g kg−1 total N) was not affected by N fertilizer. The average AFN concentration was 93 g kg−1 total N. Nitrogen fertilizer did not affect herbage quality; however, age of herbage had marked effects on herbage quality.
The performance of high‐latitude grass varieties under Scottish conditions: seasonal distribution of dry‐matter production
Authors: HAY R. K. M.
Published: April 2006

The seasonal patterns of dry‐matter (DM) production by swards of Norwegian grasses originating from high latitudes >61°N (Dactylis glomerata Hattfjelldal, Phleum pratense Engmo and Poa pratensis Leikra) were compared over 2 years (1986 and 1987) with those of grasses developed at lower latitudes, 52°N (Dactylis glomerata Cambria, Phleum pratense Motim and Lolium perenne Perma) at a lowland site in southwest Scotland (55.5°N, altitude 45 m). In each year, there was a significant enhancement of the DM production of the high‐latitude varieties of Dactylis glomerata, Phleum pratense and Poa pratensis at harvests during May and June, although the lower latitude grasses gave a higher proportion of annual production than the Norwegian grasses in April and from September onwards. These findings are compatible with the observed stimulation of DM production of high‐latitude grasses by daylength extension under controlled conditions. However, since the stimulation of DM production did not occur until the normal peak of production in May and June, it served to accentuate the skewed distribution of production in Scotland, rather than to improve production earlier in the season. Since the total annual DM production was significantly lower for the high‐latitude grasses in general at the lowland site, there does not appear to be a clear role for these grasses in UK agriculture.
Assessment of contrasting perennial ryegrasses, with and without white clover, under continuous sheep stocking in the uplands
Authors: DAVIES D. A. , FOTHERGILL M. , JONES D.
Published: April 2006

Potential lamb production from grass‐clover (75–80 kg N ha−1) swards was compared with that from grass‐only (160–200 kg N ha−1) swards from 1985 to 1987 at the Bronydd Mawr Research Centre in mid‐Wales. Separate pastures of three perennial ryegrass (Lolium perenne L.) varieties; Aurora (very early‐flowering diploid), Meltra (late‐flowering tetraploid) and Aberystwyth S23 (late‐flowering diploid), with and without Aberystwyth S184 small‐leaved white clover (Trifolium repens L.), were continuously stocked with Beulah Speckled Face ewes and their Suffolk cross lambs from spring (late April) until weaning in mid‐July. From late July the pastures were grazed with weaned lambs until early November.

Individual lamb liveweight gain was 8% more (P < 0·001) pre‐weaning on grass‐clover than on grass‐only swards and 30% more (p < 0·001) post‐weaning. Averaged over three years, mean stocking rate was 17% higher (p < 0·001) pre‐weaning and 29% higher (p < 0·001) post‐weaning on the grass‐only pastures. Even so, total lamb output (kg ha−1) was similar from the two sward types, although during the pre‐weaning period lamb production was 9% higher (P < 0·05) from grass‐only swards.

The results show the potential of grass‐clover (low N) swards to improve the efficiency of lamb production from grassland since better individual lamb growth rate compensated for the lower stock‐carrying capacity. That is, similar output was achieved with lower cost of fertilizer N input and with the lower costs associated with carrying fewer animals.
Slot‐seeding investigations 7. The effects of two grasssuppressants on the growth of white clover introduced into permanent pasture
Authors: STANDELL CHRISTINE J.
Published: April 2006

The benefits of reducing competition from the surrounding grass sward against slot‐seeded clover were measured in terms of white clover dry matter production following applications of two grass‐suppressing herbicides, propyzamide and carbetamide.

Clover was slot‐seeded in early June 1983 and herbicides were applied in September and October 1983. The later application was more damaging to the surrounding sward. Generally, the September spraying was more effective in encouraging white clover, especially from July of the following year. Only by September 1984 did the October applications result in higher clover yields than the September applications.

Propyzamide had the greater stimulatory effect on white clover production but it also damaged the grass more than carbetamide. Increasing the dose of each herbicide increased grass damage. However, with treatments applied in September, the loss was more than compensated for by an increase in clover and in total dry matter production at the end of the year.

The results suggest that either of these herbicides, but especially propyzamide, can be used to increase both total dry matter production from the sward and the contribution from slot‐seeded white clover.
Comparison of the fermentation quality and nutritive value of sulphuric and formic acid‐treated silages fed to beef cattle
Authors: KENNEDY S. J.
Published: April 2006

Five experiments were carried out in the years 1980‐1983 and 1986 to study the effect of treating grass at ensiling with sulphuric acid (850 g kg−1) and formic acid (850 g kg−1) additives alone, and in mixtures with or without formalin on the preservation of grass, in vivo digestibility in sheep, in‐silo loss, intake and performance of finishing cattle.

Primary growth grass was ensiled in experiments 1 (3–4 June 1980), 2 (12‐15 June 1981) and 3 (31 May‐2 June 1982), primary regrowth grass in experiment 4 (1‐2 August 1983) and secondary regrowth grass in experiment 5 (7‐10 October 1986). During the ensiling period within each experiment, approximately 60 t of unwilted, double‐chopped, additive‐treated or untreated grass was packed into covered concrete‐walled 60‐t capacity silos. The dry matter (DM) contents of the ensiled grass in experiments 1, 2 and 5 ranged from 155‐180 g kg−1 and were lower than those recorded in experiments 3 and 4 (214 g kg−1). With the exception of grass ensiled in experiment 2, where water‐soluble carbohydrate (WSC) contents were low, at 104 g kg−1 DM, grass in all other experiments contained relatively high WSC contents ranging from 140‐154 g kg−1 DM.

In experiments 1, 3 and 4 all silages were well‐preserved. However, in experiment 2 the 450 g kg−1 sulphuric acid‐treated and formic acid‐treated silages displayed significantly lower pH, buffering capacity (Bc) and ammonia nitrogen contents than the untreated silage. In experiment 5, the sulphuric acid‐treated and formic acid‐treated silages displayed significantly lower pH, Bc, ammonia nitrogen, butyrate and volatile fatty acid (VFA) contents than the untreated silage.

Each of the silages was offered daily with various levels of a supplementary concentrate for approximately 70‐d periods to twelve animals of mixed breed in experiments 1, 3, 4 and 5 and to fifteen animals in experiment 2. All animals weighed between 380‐470 kg at the start of the experiments.

In experiments 1, 2 and 3 there were no significant differences between silages for any of the intake or animal performance parameters. In experiment 4, cattle fed the formic acid‐treated silage displayed significantly higher silage DM intakes and daily liveweight gains than those fed the sulphuric acid‐treated and untreated silages; in experiment 5, cattle fed the formic acid‐treated silage displayed significantly higher silage DM intakes than those fed the untreated silage. It was concluded that formic acid was a more effective silage additive than sulphuric acid.

Increasing the level of supplementation significantly decreased silage DM intakes in cattle in experiments 3 and 4, and significantly increased daily liveweight gains and daily carcass in cattle in experiments 1, 3 and 4.
Sward canopy structure and the bite dimensions and bite weight of grazing sheep
Authors: BURLISON A. J. , HODGSON J. , ILLIUS A. W.
Published: April 2006

Seventeen grass or oats swards, displaying a wide and largely independent variation in surface height and bulk density, were produced using different seed rates at sowing and different cutting or grazing pre‐treatments. Four sheep confined in cages were allowed to take twenty bites from small patches of each sward, and measurements of bite weight and the physical dimensions of the average bite in the sward (bite depth, area and volume) were related to a range of sward structural characteristics.

Mean bite weight per sward ranged from 40 to 330 mg dry matter (DM). It was positively related to surface height (range 6–55 cm), which acted primarily upon bite depth and hence bite volume, and to the bulk density of the grazed stratum (range 0·1–2·0 mg DM cm −3) which influenced bite weight directly. The effects of surface height and grazed stratum bulk density were independent and additive, resulting in a planar response surface.

The influence of sward variables on bite area was less clear than on bite depth, but within a given grass species the effect of surface height appeared to be positive and that of the population density of grazed leaves and stems negative. These findings are considered in relation to a theory concerning grazing mechanics.

The merits of the grazing cage technique are discussed and suggestions made for further work.
Assessment of contrasting perennial ryegrasses, with and without white clover, under continuous sheep stocking in the uplands. 3. Herbage production, quality and intake
Authors: DAVIES D. A. , FOTHERGILL M. , JONES D.
Published: April 2006

Herbage characteristics were monitored over 3 years (1985–1987) in three perennial ryegrass (Lolium perenne L.) varieties as grass/only (200 kg N ha−1) and grass/clover (Trifolium repens L.) (75 kg N ha−1) swards when continuously stocked with sheep. Although mean total annual herbage production was similar from the grass varieties, growth of Aurora, a very early‐flowering variety, was higher than that of Aberystwyth S23 and Meltra (tetraploid) late‐flowering types in spring. Herbage production from grass‐only swards was 15% higher than from grass/clover swards.

In vitro organic matter digestibility (OMD) of Aurora and Meltra was 34 g kg −1 and 26 g kg −1 higher (P < 0·01) than that of S23. Averaged over varieties, the OMD of grass/clover was 25 g kg −1 higher (P < 0·05) than grass‐only during the post‐weaning period. Individual lamb digestible organic matter intake (DOMI) was 22% higher (P < 0·05) on grass/clover than on grass‐only during this period. Water‐soluble carbohydrates content of Aurora was 42% higher (P < 0·001) than that of both Meltra and S23.

Herbage characteristics were related to lamb performance reported previously. Lamb production was positively correlated with DOMI. However, the magnitude of differences in lamb performance between treatments was much greater than the extent of differences detected in herbage characteristics.
The effect of rate and timing of phosphate fertilizer on the yield and phosphate off take of grass grown for silage at moderate to high levels of soil phosphorus
Authors: PAYNTER R. M. , DAMPNEY P. M. R.
Published: April 2006

A series of twenty‐one trials was undertaken during 1985–1988 to investigate the effect on lowland silage crops of 0, 40 or 80 kg ha−1 phosphate (P2O5) fertilizer applied as triple superphosphate (46% P2O5) in the autumn, spring or as a split application (spring and after first cut). All sites had moderate to high sodium bicarbonate‐extractable soil phosphorus contents (18–34 mg P 1−1 in air‐dried soil).

Significant yield responses were obtained at eight of the forty‐two individual cuts (two cuts per site). When meaned over all sites, spring or autumn applied phosphate increased dry matter yield at both first and second cut (mean total increase 0·32 t ha−1), though the effect was significant only at the highest phosphate rate. The time of phosphate application had no overall effect on yield. Herbage P concentration and phosphate off take were significantly increased at both cuts by both rates of phosphate. Generally, the most recent application had a significantly greater effect than other timings. These findings indicate that DM yield responses to freshly available phosphate can occur on soils of moderate P status.
Supplementary forage for grazing sheep. 2. Effects on weaned lambs
Authors: MARTIN J. H. , PHILLIPS C. J. C. , ALCOCK M. B.
Published: April 2006

In two experiments weaned entire ram lambs were offered either pasture alone or pasture plus ad libitum conserved forage for 7–12 weeks during the finishing period. Herbage height was maintained at 3·2 cm on both treatments by manipulation of stocking rate in the twenty‐four plots (twelve per treatment) used for the experiment. In experiment 1 silage, which was of lower metabolizable energy (ME) and crude protein (CP) content than the grazed herbage, was consumed at an average of 194 g DM head−1 d−1, providing approximately 40% of total DM intake requirements. In experiment 2 a strawmix, containing (g k g −1 freshweight) 450 g barley straw, 300 g concentrate and 250 g molasses and again with a lower ME and CP content than the grazed herbage, was consumed at an average of 57 g DM head−1 d−1, providing approximately 11% of total DM intake requirements. In both experiments stocking rate was increased by 20–25% by providing forage, but lamb growth rate was not affected.
Differences in lamina wettability in some permanent pasture grass species and two Lolium perenne cultivars
Authors: TALLOWIN J. R. B. , TYSON C. M. , BROOKMAN S. K. E.
Published: April 2006

Lamina wettability, assessed using water droplet contact‐angle and surface water‐retention measurements on excised leaves, was examined in Lolium perenne cv. Melle, cv. Condesa and an indigenous population from an old pasture, Holcus lanatus, Poa trivialis and Agrostis stolonifera. The species fell into two significantly distinct categories, those with unwettable laminae, namely H. lanatus and A. stolonifera, and those with highly wettable laminae, P. trivialis and the three L. perenne populations. There was no significant difference between the L. perenne populations, which had the most wettable laminae overall. The possible implication of these differences in lamina wettability on animal production is discussed.
Wheel‐induced soil compaction effects on ryegrass production and nitrogen uptake
Authors: DOUGLAS J. T. , CRAWFORD C. E.
Published: April 2006

Soil and crop responses to zero, small and large tyre/soil contact stresses applied by tractors were studied on a newly reseeded ryegrass sward during 1987 and 1988. The compactive efforts, applied during winter or at the time of spring fertilizer application or at first harvest, were sufficient to increase significantly bulk density in the topsoil layer compared with that in a zero traffic control treatment. The largest increases in soil bulk density occurred after spring‐time traffic in the first year (1987) of the experiment. In both years, the resulting soil conditions after heavy compaction were relatively unconducive to primary grass growth and first cut yields; the soil was wetter (less well aerated), of greater strength and colder in the early spring, and warmer in the late spring than the soil in the zero and more lightly compacted treatments. During a relatively wet summer (1987) there were significant benefits to second and third cut yields from minimizing compaction; in the relatively dry summer of 1988 there were no compaction effects at second cut. In both years, impaired uptake of nitrogen was related closely to increased amount of traffic and soil density.
Degradation of nitrogenous compounds in conserved forages in the rumen of dairy cows
Authors: TAMMINGA S. , KETELAAR R. , van VUUREN A. M.
Published: April 2006

Degradation in the rumen of dairy cows of nitrogenous compounds in 35 grass silages and 12 grass hays was studied by means of the nylon bag incubation technique. Silages varied in dry matter content, crude protein content and date of harvesting; hays varied mainly in crude protein content. Measurements in both forages were washable (W), degradable (D) and undegradable fraction (U) and rate of degradation (ks) of D. W and U were measured as the residue after washing without incubating (W) or after 336 h in the rumen (U). N escape (E) was calculated from these data, assuming a ruminal passage rate of 4·5% per hour.

E (N escape from the rumen) in hays was substantially higher than in silages, mainly because a large proportion of N compounds in silage became soluble during the ensiling process. Of the total variation in E, around 80% could be explained in both forages. In silage, E was positively influenced by dry matter content, negatively by crude protein content and positively by the number of days elapsed since 1 April. This effect of day of harvesting was mainly through an increase of U and may not be beneficial to the animal. In hays crude protein content was the major factor explaining variation in E.
Barley/pea mixtures as cover crops for grass re‐seeds
Authors: GILLILAND T. J. , JOHNSTON J.
Published: April 2006

Substantial annual fluctuations in the performance of arable silage mixtures, comprising Minerva forage pea and Goldmarker barley, were observed from ten annual sowings between 1977 and 1986, Total dry matter (DM) yield varied between 2·5 and 11·5 t ha−1. Dry matter content also ranged widely from 10·3% to 20·0% and there was a large variation in the proportion of peas in the DM (0·44 to 0·90). Almost 80% of this yield variation was due to the fluctuation in pea performance and over 60% of all yield variation was related to the variation in sunshine hours and air temperature.

In 1983 and 1984 differences in seed rate of between 20 and 140 kg ha−1 of Minerva and 80 and 160 kg ha−1 of Goldmarker influenced the forage composition at harvest, with the pea component capable of outgrowing and suppressing the other species when sown at over 80 kg ha−1. Very high yields of peas were associated with increasing stress on the undersown grass re‐seed and were considered undesirable.

It was concluded that sowing rates of between 120 and 160 kg ha−1 for barley and a maximum of 60 kg ha−1 for peas would, in most years, provide the best compromise between attaining good arable silage yields and avoiding excessive dangers of damage of undersown grass re‐seeds.
An integrated methodology for studying short‐term grazing behaviour of cattle
Authors: LACA E. A. , UNGAR E. D. , SELIGMAN N. G. , RAMEY M. R. , DEMMENT M. W.
Published: April 2006

Grazing studies are hampered by difficulty in controlling the characteristics of that part of the sward encountered by animals. A methodology was developed to study the effects of sward height, density and spatial arrangement on bite dimensions, bite weight and instantaneous intake rate by cattle. Hand‐constructed swards (HCS) consisted of tillers threaded through wooden modules and attached to a base board. The microphone of a cordless transmitter was attached to the forehead of steers before swards were grazed. HCS were bolted onto a force plate which recorded the forces exerted during grazing. Grazing sessions were videotaped. Height and density of swards were successfully controlled by hand‐construction. Bite weight was determined more accurately by dry matter (DM) disappearance than by the reduction of fresh weight corrected for moisture loss and herbage DM content. Bite area and bite depth were precisely measured by counting and measuring the residual height of grazed plant parts. Bites and chews were identified and counted from the soundtrack of video tapes. Visual count of chews was inaccurate because animals can prehend new herbage and chew herbage previously gathered with the same jaw movement. Many jaw movements involve only manipulation of herbage without biting or chewing. Bite dimensions result from the physical interaction of relatively fixed motor patterns, such as tongue sweeps, with vegetation structure. Thus, bite dimensions measured by this technique are relevant to field situations.
The role of the legume in the nitrogen cycle of productive and sustainable pastures
Authors: THOMAS R. J.
Published: April 2006

The role of the legume in the nitrogen (N) cycle was examined in grazed pastures receiving no N fertilizer of both temperate and tropical regions by simulating the fluxes of N through different processes of the cycle. The amounts of legume‐fixed N required to balance the cycle without invoking a drain on soil organic N reserves (i.e. no net N mineralization) was estimated to vary from 38 to 53% of the above‐ground herbage N or from 20 to 31% on a dry matter (DM) basis for tropical pasture systems with a range of pasture utilization of 10–40%. At higher pasture utilization levels of 50‐70%, more typical of intensively grazed temperate pastures, the N input requirement in the absence of fertilizer N would be 57‐67% of the aboveground herbage N or 35‐45% DM. An examination of the role of each contributory process of recycling (viz. excreta returns, internal cycling or remobilization from senescing tissues, litter decomposition) suggests that variations in the amounts of internally cycled N would have the greatest impact on the requirement for biologically fixed N at low levels of pasture utilization (10‐40%), while at high pasture utilization levels of 70%, variations in the recovery of excreta‐N would have a major effect on the requirement for fixed‐N to balance the cycle.

The amounts of biologically fixed N required to sustain a range of herbage DM yields of 3‐22 t DM ha −1 yr−1 would range from 15 to 158 kg N ha−1 yr−1 for tropical pastures. For intensively managed temperate pastures producing 6‐15 t DM ha−1 yr−1 with a N content of 3·5%, a range of fixation of 120‐352 kg N ha−1 yr−1 is required. These simulations indicate how legume contents of 20‐45% of herbage DM could contribute to productive and sustainable (in terms of N) pasture systems of both temperate and tropical regions
The potential transmission of clover rot, Sclerotinia trifoliorum Erikss., by slugs
Authors: SHAKEEL M. A. , MOWAT D. J.
Published: April 2006

Slugs of three species, Deroceras reticulatum, Arion fasciatus and A. subfuscus, which had fed on sclerotia or apothecia of Sclerotinia trifoliorum, transmitted the disease to water agar plates. In the case of Arion spp., transfer of excreta also produced infection.

After feeding on apothecia D. reticulatum transmitted the disease to white clover plants, although the direct transfer of apothecia produced higher levels of infection. The visible symptoms of the disease were reduced when slugs were allowed to remain on the plants, apparently owing to a feeding preference of D. reticulatum for diseased leaf tissue.
The effects of temperature on digestibility of timothy (Phleum pratense L.), tested in growth chambers
Authors: THORVALDSSON G.
Published: April 2006

Plants were grown in pots outdoors and placed in four growth chambers at different temperatures (day temperatures 9, 13, 17 and 21°C) and at three different phenological stages. They were then harvested at weekly intervals for up to 6 weeks. Pots left outdoors were harvested at the same time.

Digestibility was nearly constant during the 6 weeks at the lowest temperature. The rate of decline in digestibility per day, calculated from that portion of the data which was assumed to be best for such estimation, was 0·060±0·008 per cent units for each degree increase in temperature.

The results indicate that the temperature effect on decline in digestibility is the same for early as for late growth stages.
Evaluation of white clover varieties under grazing and their role in farm systems
Authors: EVANS D. R. , WILLIAMS T. A. , EVANS S. A.
Published: April 2006

Four experiments were established in 1981–84 to investigate the effect of defoliation treatments on white clover varieties when grown with S23 perennial ryegrass. Treatments included a cutting only regime, as used in National List trials, and grazing systems simulating as near as possible those used on farms.

Differential effects of cutting and continuous sheep stocking on white clover varieties, together with significant variety × defoliation interactions, illustrated the importance of the grazing animal in the evaluation of white clover. Differential effects of cattle and sheep grazing were also evident. Cattle grazing was less detrimental to white clover than was sheep grazing, i.e. cattle were not selective, and less stolon was removed. In general, with both cattle and sheep grazing the larger the clover leaf size the greater the loss in stolons, which in turn decreased persistency. The results illustrate how alternating cutting, sheep grazing and cattle grazing managements can be used to maintain optimum clover/grass balance.

Successful clover/grass swards depend on the retention of clover, yet avoiding clover dominance. The difference in N transfer between clover varieties, especially those within the same leaf category, and the extra grass produced without fertilizer N, emphasized the importance of varietal choice. Breeding programmes have been concerned with the selection of larger‐leaved, long‐petioled varieties for growing in competition with grass in the presence of fertilizer N. However, the present results showed that, under continuous sheep stocking, increase in leaf size does not increase clover yield or persistency.

The results presented emphasize the importance of the grazing animal in the evaluation of white clover varieties and indicate that yield of clover dry matter should not be the major criterion for selection of varieties for farm systems.
Anatomical structure and digestibility of reed canarygrass cultivars and hybrid ryegrass
Authors: GRABBER J. H. , ALLINSON D. W.
Published: April 2006

Anatomical structure and fibre chemistry influence the digestibility of forage grasses. The objective of this study was to evaluate the anatomical structure, digestibility, and fibre composition of leaf blades from a high alkaloid and two low alkaloid cultivars of reed canarygrass (Phalaris arundinacea, L.) and one cultivar of tetraploid hybrid ryegrass (Lolium hybridum, Hausskn.). Cultivars were grown in a greenhouse in a randomized complete block design with four replications. Leaf blades were either cut into 10‐mm sections or dried and milled to disrupt anatomical structure.

Reed canarygrass had smaller cells and airspaces and slower tissue digestion than ryegrass. The in vitro disappearance of ryegrass sections in buffered rumen fluid was 60% greater (P<0·01) than that of reed canarygrass after 6, 12 and 24 h of digestion. By contrast, the in vitro disappearance of milled ryegrass was similar to or less (P<0·05) than that of reed canarygrass. In vitro dry matter digestibility and fibre composition of the grasses were similar except for acid detergent fibre, which was greater (P<0·01) in ryegrass than in reed canarygrass. Reed canarygrass cultivars were similar in anatomical structure, digestibility, and fibre composition. It was concluded that the digestion of reed canarygrass, relative to ryegrass, was reduced by the compact arrangement of tissues and that alkaloid content did not influence the digestion of reed canarygrass cultivars.
Causes of low seed set in white clover (Trifolium repens L.)
Authors: PASUMARTY S. V. , MATSUMURA T. , HIGUCHI S. , YAMADA T.
Published: April 2006

A field experiment was conducted to clarify the factors responsible for poor seed set in four white clover (Trifolium repens L.) cultivars. Although the mean number of ovules per floret was 5·18–5·29, the average number of seeds per floret was found to be only 1·23‐1·82. A stainclearing technique was used to examine the cytoplasmic state of the embryo sac in intact, unfertilized, mature ovules and it was found that 28–33% of ovules per carpel were sterile. The abortion rate of fertilized ovules and immature seeds (7 days after pollination) ranged between 32 and 34%. Beyond this period, it was observed that only a very small proportion of the total seeds were lost. The observation of high pollen fertility and a high pollen load strongly suggests that poor pollination does not account for the reduced number of seeds per floret. A ‘nutrient competition’ hypothesis was proposed for high ovule sterility and post‐fertilization abortion of developing seeds.
A comparison of diploid and tetraploid perennial ryegrass and tetraploid ryegrass/white clover swards under continuous sheep stocking at controlled sward heights. 2. Animal production
Authors: VIPOND J. E. , SWIFT G. , McCLELLAND T. H. , FITZSIMONS J. , MILNE J. A. , HUNTER E. A.
Published: April 2006

Performance of continuously stocked Mule ewes nursing Suffolk‐cross twin lambs over three grazing seasons, between April and August, was compared on swards of N‐fertilized diploid perennial ryegrass (D), tetraploid perennial ryegrass (T) and tetraploid perennial ryegrass with white clover (TC), the latter receiving no fertilizer N. Sward height was maintained by variable stocking rate close to a target of 4–6 cm (constant treatment) from turnout and compared in July and August with a rising sward height treatment (target 6–8 cm).

Lambs on TC swards had significantly higher (P <0·001) liveweight gains compared with lambs on T swards by 41 gd‐1 in April–June and by 68gd‐1 in July‐August. Live weight and body condition score of ewes in August were significantly higher (P<0·001) on TC compared with T swards, by 11·3 kg and 0·75 respectively. Rising sward heights in July–August increased live‐weight gain of lambs compared with constant sward heights by 102, 39 and 54gd‐1 in consecutive years, associated with sward height increases of 0·9, 0·5 and 0·6cm respectively. Rising sward height increased ewe live weight and body condition score by 5·1 kg and 0·3 respectively, compared with results from constant sward heights. Effects of sward height and sward type were additive.

T swards had a significantly (P<0·01) 16% greater overall lamb output than the D swards due mainly to a 10% higher achieved stocking rate. Stocking rates of ewes on TC vs T swards were 40, 13 and 12% lower in April‐August in successive years. The higher liveweight gain of lambs on the TC swards resulted in lamb outputs of 76, 105 and 101% of the T swards in successive years, showing that grass/clover swards containing over 20% clover could produce similar lamb output ha‐1 to grass swards given 150–180 kg N ha‐1.
Plant interference and chemical toxins in upland pastures
Authors: NORRINGTON‐DAVIES J. , BUCKERIDGE D. J.
Published: April 2006

Supernatants derived from desiccated plant material gathered from Agrostis/Festuca vegetation had an inhibitory effect on the germination and early development of seedlings of Trifolium repens cv. S184. Two compounds, o‐hydroxyphenylpropionic acid and benzoic acid, were identified chromatographically and their structures confirmed by mass spectrometry. Commercial preparations of the two compounds were effective inhibitors at a concentration of 10−2 and 10−3m respectively when T. repens was used as the phytometer species. Benzoic acid lost its inhibitory effect when the pH of the two solutions was adjusted to pH 5·5. The roots of seedlings of white clover were severely distorted by o‐hydroxyphenylpropionic add at 10−3m. It is likely that phenolic acids, produced from the surface trash created by slot seeding procedures, interfere with the establishment of white clover in upland pastures.
Effects of inoculant treatment on silage fermentation, digestibility and intake by growing cattle
Authors: KEADY T. W. J. , STEEN R. W. J. , KILPATRICK D. J. , MAYNE C. S.
Published: April 2006

A changeover design experiment involving thirty‐six 3‐month‐old Friesian male calves (mean initial live weight 127 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum (Ecosyl, ICI) as a silage additive. On 25–31 August 1988, nine silages were harvested using double‐chop forage harvesters from the second regrowth of three swards, namely permanent pasture which had received 100 kg N ha−1 and perennial ryegrass which had received either 100 or 150 kg N ha−1. Herbages (mean DM and WSC concentrations 144 and 11·2 g kg−1 respectively) from each sward were treated with either no additive, formic acid (2·4 1 t−1) or the inoculant (3·3·1 t−1) and were ensiled in 126 silos of 0·8 t capacity. The only effects of the inoculant on chemical composition of the silages were a decrease in modified acid detergent fibre and an increase in endotoxin and crude and true protein concentrations. Silages were offered ad libitum and supplemented with 1·0 kg of concentrates per head daily for three periods each of 3 weeks in a partially balanced changeover design experiment. Digestibilities of the total diets were determined at the end of the experiment. For the untreated, formic acid‐treated and inoculant‐treated silages, silage dry matter intakes were respectively 3·58, 3·66 and 3·67 (s.e. 0·044) kg d−1, estimated metabolizable energy (ME) intakes were 46·1, 46·7 and 47·1 (s.e. 0·44) MJ d−1, energy digestibilities were 0·727, 0·727 and 0·738 (s.e. 0·0046) and organic matter digestibilities were 0·770, 0·771 and 0·788 (s.e. 0·0042). Rumen degradabilities of the silages were determined using two rumen‐fistulated cows. Mean dry matter and nitrogen degradabilities for the control, formic acid‐treated and inoculant‐treated silages, assuming an outflow rate of 0·05 h−1, were 10·508, 0·49, 0·491 and 0·702, 0·676 and 0·729. It is concluded that the inoculant significantly increased the digestibility of the silages but did not affect dry matter or ME intake.
Managing grass/clover swards to produce differing clover proportions
Authors: YARROW N. H. , PENNING P. D.
Published: April 2006

Management treatments were applied to an established ryegrass/white clover sward with the aim of producing differences in clover content. The treatments were: mowing (M) with no fertilizer N (intended to give high clover), grazing by cattle (C) with no fertilizer N (medium clover) and grazing by sheep (S) with 300 kg N ha−1 applied (low clover). Following treatments significant differences (P < 0.001) were observed, with M, C and S containing respectively. 237, 81 and 3 kg DM ha−1 of live clover. Treatment M swards had fewer ryegrass tillers but greater numbers of clover growing points than did treatment S, with values being intermediate on treatment C. Following overwintering most of the differences in the clover component between treatments C and M were lost, but those on treatment S still persisted. Management can be used to manipulate the botanical composition of ryegrass/white clover swards, but these changes may be only transient.
Leaf number as a criterion for determining defoliation time for Lolium perenne: 2. Effect of defoliation frequency and height
Authors: FULKERSON W.J. , SLACK K.
Published: April 2006

The object of this study was to determine the importance of frequency and height of defoliation on regrowth potential of Lolium perenne. Defoliation interval was based on stage of the regrowth cycle, as indicated by leaves per tiller.

Simulated swards of Lolium perenne cv Yatsyn were grown as individual plants in a glasshouse kept at a day/night temperature of 25°C/15°C.

Treatments imposed were defoliation at 2, 5 or 12 cm residual height, and low and high water soluble carbohydrate (WSC) level obtained by varying defoliation interval, i.e. defoliating at the 1‐leaf or 3‐leaf stage of the regrowth cycle. Regrowth after frequent short defoliations was only 65% of the less frequently defoliated plants taken over the full regrowth cycle. This was associated with a lower stubble WSC content (2·15 vs 17·5% in stubble) and a twenty‐seven‐fold difference in the amount of WSC in the stubble per plant. This difference in total WSC was a combined effect of more and heavier tillers and higher WSC content in stubble of plants defoliated less frequently at the end of the regrowth cycle. The regrowth of plants with WSC levels depleted by frequent defoliation when defoliated at 2 cm was significantly below that of those defoliated at 5 and 12 cm.

The results indicate the desirability of defoliating plants at the 3‐leaf stage of the regrowth cycle. This not only allows the full regrowth potential to be expressed in that growth cycle, but also in the next cycle, by allowing the replenishment of WSC reserves and optimizing tiller status. The potential to regrow appears then to be based more on the total amount of WSC than the proportion of WSC in stubble.
The effect of light intensity after anthesis on dry matter distribution and seed yield of Lolium perenne L.
Authors: WARRINGA J. W. , MARINISSEN M. J.
Published: April 2006

The effect of light intensity after onset of anthesis on dry matter distribution, water soluble carbohydrate (WSC) concentration and seed filling in Lolium perenne was investigated in a pot experiment. Spaced plants of five clones were brought to flowering and exposed to four light intensities (24%, 57%, 100%, 115% of natural light) from 7 days after onset of anthesis onwards. The two oldest flowering tillers (i.e. the main and the first tiller) were separated from the rest of the plant and dissected after a seed‐filling period of 450°Cd (temperature sum counting from 7 days after onset of anthesis). Their stem dry weight and WSC concentration were reduced at the lowest light intensity. WSC amount was more reduced in the first, younger, tiller. Seed yield per ear of the main tiller was reduced by 14% because seed set and average seed weight were lower at the 24% light intensity. Seed yield and seed number per ear of the first tiller were lowered by 21% and 17%, respectively, at the 24% light intensity, but average seed weight was not. The relative contribution of the seeds to total tiller weight was about 20% and was similar for both tillers and all light intensities. WSC concentration and WSC amount in the stem + rachis were reduced only at 24% light in the main tiller and at 24% and 57% light in the first tiller. It is inferred that seed yield was not limited by assimilate availability, but by the ability of the seeds to utilize fully the abundantly available reserves in the stem. The tiller can support seed yield under a wide range of tight intensities.
The effects of ensiling on dry‐matter intake and milk production by lactating dairy cattle given forage as the sole feed
Authors: KEADY T. W. J. , MURPHY J. J. , HARRINGTON D.
Published: April 2006

An experiment involving forty‐five British Friesian cows in mid‐late lactation was carried out to evaluate the effects of ensiling on herbage digestibility, dry‐matter intake and milk production. The herbage from the primary growth of a predominantly perennial ryegrass sward that had received 123 kg N ha−1 was zero grazed (ZG) from 27 April to 24 May 1992. Before going onto the experimental diets all animals were offered a common silage as the sole diet and dry‐matter intakes and milk yields were recorded. The herbage was mown, picked‐up with a precision‐chop harvester and offered as the sole diet, twice daily, 10 fifteen cows that were on average 176 days into lactation. On May 20 herbage from the same sward was harvested identically to the ZG herbage and ensiled, alternative loads being untreated (UT) or treated with formic acid (2.4 l−1) (FA). For silages UT and FA respectively, pH values were 3.94 and 3.92 and ammonia nitrogen concentrations were 95 and 75 [g(kg total N−1)]. Forty‐two days after ensiling, the silages were fed twice daily as the sole diet to thirty cows which were on average 166 days into lactation. The feeding interval was 28 days and the last 7 days was the main recording period for each treatment. For diets ZG, UT and FA, dry‐matter intakes (DMI) (kg d−1), milk yields (kg d−1), fat plus protein yields (kg d−1). milk fat concentration (g kg−1), milk protein concentration (g kg−1)and fat plus protein yields [kg (kg DMI)−1] were 12.70, 11.51 and 12.07 (Av s.e.d. = 0.458); 12.79, 10.01 and 10.18 (Av s.e.d. = 0.346); 0.900, 0.649 and 0.682 (Av s.e.d. = 0.026); 39.8, 33.7 and 36.7 (Av s.e.d. = 0.174); 32.9, 29.9 and 30.0 (Av s.e.d. = 0.83); 0.073, 0.055 and 0.055 (Av s.e.d. = 0.003). UT treatment significantly increased dry matter (DM), organic matter (OM). energy and crude fibre digestibilities and the digestible OM concentration. UT and FA compared with ZG altered rumen fermentation patterns, significantly decreasing butyrate and increasing valerate concentrations. FA treatment significantly decreased the non‐glucogenic ratio. It is concluded that ensiling using formic acid had no effect on forage DMI relative to the parent fresh herbage. Ensiling either untreated or with formic acid significantly decreased milk yield and milk fat plus protein yield, resulting in a lower efficiency of conversion of DMI to milk fat plus protein.
A new technique to describe canopy characteristics of grass swards with spatial distribution, dry‐matter digestibility and dry weight of small‐size canopy components
Authors: HIRATA M.
Published: April 2006

A new technique describing canopy characteristics of grass swards was developed In this technique, the sward canopy is regarded as a set of canopy components which are 2‐cm‐long segments of leaves and stems, and the spatial distribution, dry‐matter digestibility (DMD) and dry weight of the components are estimated. The technique was applied to a canopy of a bahia grass (Paspalum notatum Flügge) pasture in spring, summer and autumn. The spatial distribution in terms of the quantity and quality of components within the canopy can be described as can the dry weights of material in different DMD classes. From these descriptions, some important canopy characteristics were highlighted that cannot be identified with other techniques. They were the variation in DMD within a canopy, the possible difficulty for animals in discriminating between the components within a prehension bite, and the reduction in summer in the proportion of highly digestible components. Because of the way in which the canopy characteristics were described and the importance of the canopy characteristics highlighted, the technique is considered to be of potential value for describing canopy characteristics in relation to sward‐animal interactions during grazing.