bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling mineral nitrogen accumulation in grazed pasture: will more nitrogen leach from fertilized grass than unfertilized grass/clover?
Authors: HUTCHINGS N. J. , KRISTENSEN I. S. 
Published: April 2006

AbstractA model of herbage growth and nitrogen dynamics for grazed pasture was developed. Grazed herbage nitrogen is partitioned between animal growth, urine and faeces. After allowing for ammonia volatilization, the rate and area covered by urinary nitrogen is simulated. The fate of each day's urinary nitrogen deposition is followed separately through time. The mineral nitrogen remaining in the soil at the end of the growing season is assumed to be leached over winter. Leaching from fertilized grass only and unfertilized grass/clover pastures are compared at varying levels of dry matter (DM) production. Biological fixation is assumed to provide sufficient nitrogen to allow the grass/clover pasture to achieve the same seasonal distribution of production as the fertilized grass‐only pasture. There was a non‐linear increase in predicted leaching with increasing DM production owing to the aggregation of urinary nitrogen into urine patches. Leaching was lower from grass/clover than the grass‐only pasture and the difference increased with DM production. At levels of production common in the UK, the difference in leaching between the two pasture types was small and the spatial distribution of soil mineral nitrogen was uneven, so differences in leaching may be small and difficult to detect.
Peduncle characteristics, inflorescence survival and reproductive growth of white clover (Trifolium repens L.)
Authors: MARSHALL A. H. 
Published: April 2006

AbstractField experiments were carried out in four harvest years to compare the peduncle characteristics and reproductive growth of the small‐leaved white clover (Trifolium repens L.) cv. AberDale, selected for long and strong peduncles, with other varieties bred in the Institute of Grassland and Environmental Research (IGER). The peduncles of cv. AberDale were of larger diameter and had a greater fresh and dry weight than those of other varieties. There were also differences in structure as the peduncles of cv. AberDale had more pronounced ridges and furrows than those of cv, Menna.Inflorescences of cv. AberDale and other varieties were tagged when in full bloom throughout the flowering period in each of the four harvest years. Generally, more inflorescences of cv. AberDale remained intact until harvest, particularly from the early tagging dates. Although there were seasonal differences, at harvest in each of the 4 years, cv. AberDale had more inflorescences and seeds per floret and a greater potential seed yield than the other varieties.The basis of peduncle strength and effect on reproductive growth is discussed, and the implications for improving the seed yield potential of white clover varieties is considered.
The influence of autumn management and companion grass on the development of white clover over winter in mixed swards
Authors: PATTERSON J. D. , LAIDLAW A. S. , McBRIDE J. 
Published: April 2006

AbstractThree experiments designed to investigate different facets of autumn management on white clover stolon development are described. The effects of defoliation interval (2, 4, 6 and 8 weeks during 16 weeks from 27 July) were investigated. The shortest interval resulted in the shortest length of stolon material per unit area but cutting interval had no effect on growing point density nor on hardiness of stolon tips evaluated in October, December and January.Chemical grass suppressants were employed to reduce grass biomass during winter in two experiments to evaluate the influence of grass on white clover development. One experiment involved varying grass tiller density by spraying a perennial ryegrass/white clover sward in October with three rates of three chemical suppressants (Clout, Kerb and Checkmate). Although tiller and clover growing point density were inversely related in January, the overall relationship was not strong.Clout at l·5kg a.i. ha−1 was sprayed in October on one of two subplots in each of twelve grazed grass/white clover plots that had been maintained at 7 or 9 cm from July to October then grazed to 3–4 cm with sheep. Sward height had no effect on clover population density but the shorter sward had a greater mean node number per secondary stolon branch. By March, suppressing grass resulted in more than double the stolon population density, a higher proportion of plants with tertiary and quaternary branches, and on marked stolons, five times more branches and 60% higher dry matter (DM) produced during winter but with shorter petioles compared with clover in untreated plots.It is concluded that white clover has the capacity to branch during a mild winter and as stolon branch numbers can suffer a net loss as a result of the presence of the grass canopy, management that controls grass growth during winter should aid over‐wintering and improve persistence of white clover.
Effects of timing and intensity of defoliation on growth and development of white clover seedlings
Authors: HAYES M. J. , WILLIAMS E. D. 
Published: April 2006

AbstractThe effects of different defoliation regimes on the growth and development of three contrasting white clover cultivars (S184, Menna and Alice) were assessed in three experiments in the glasshouse. Experiment 1, with clover growing on its own, investigated the effects of three times of onset × two intensities of defoliation. In Experiment 2, clover was grown with grass and there were two times of onset × two heights × two frequencies of defoliation. Experiment 3, also with grass, investigated the effects of changing defoliation frequency at different intervals from sowing.All clover cultivars responded similarly to the various treatments and there were no interactions between time of onset and subsequent defoliation regimes in Experiments 1 and 2. Without competition from grass (Experiment 1), defoliating early at the three leaf‐stage of clover decreased the number of growing points by 32% and stolon weights and lengths by 50% compared with delaying defoliation until the nine leaf‐stage. Maintaining one compared with two leaves per growing point had similar effects. Over 17 weeks undefoliated seedlings produced ten times more stolon than early defoliated or intensively defoliated seedlings. In competition with grass (Experiment 2) delaying defoliation significantly decreased all aspects of stolon growth. Seedlings growing in swards defoliated frequently and closely had most growing points whereas those defoliated infrequently had least. Stolon lengths and weights were larger for seedlings growing in swards defoliated frequently than for those defoliated infrequently at both heights of cutting. Mean weight of stolon per unit length was greater when swards were defoliated at 6 cm than at 2 cm height. Changing defoliation from every 2 weeks to every week (Experiment 3) decreased stolon growth slightly when the change was made early but increased it when the change was made late, although similar amounts of stolon were produced by seedlings continuously defoliated throughout every week and every 2 weeks.The results are discussed in relation to the seedlings' leaf complements and growth habit; the over‐riding influence of grass competition is highlighted. The possibility of devising optimal defoliation strategies and the need to test these in the field are also outlined.
Productivity of Lotus corniculatus L. (bird's‐foot trefoil) in the UK when grown under low‐input conditions as spaced plants, monoculture swards or mixed swards
Authors: BULLARD M. J. , CRAWFORD T. J. 
Published: April 2006

AbstractThe dry‐matter productivity of the forage legume Lotus corniculatus (bird's‐foot trefoil) was assessed under low‐input conditions at three sites in the north of England. An initial study in 1989 and 1990 compared fourteen accessions of L corniculatus with Trifolium repens and T. pratense grown as spaced plants at two sites with contrasting soil conditions. One site represented good agricultural land, the other poor‐quality, marginal land. Yields of all species and accessions were significantly lower on the marginal site. Seasonal yields (averaged over sites) of L corniculatus cultivars averaged 52 g plant−1 and 170 g plant−1 in 1989 and 1990 respectively. General trends over both seasons were that T. repens and T. pratense yields were high but some L. corniculatus cultivars (Empire, Franco, Leo) and naturalized UK ‘aliens’ were similar to at least one Trifolium in each year. Yields from L. corniculatus ecotypes from the UK and Norway were very low in comparison with the cultivars. A largerscale study of eighteen L corniculatus, two L uliginosus, three T. repens and two T. pratense accessions was undertaken on an upland, calcareous site in 1990. Legumes were assessed in 2 m × 2 m swards as either monoculture or grass/legume mixture. Establishment and productivity of L uliginosus and T. pratense accessions were poor, with seasonal yields no greater that 50gm−2 year−1. When grown as a monoculture, L corniculatus yields were superior to both Trifolium spp., and averaged 1080 gm−2. In mixed swards, L. corniculatus constituted a higher proportion of the total dry matter yield (26% and 62% at first and second cuts, respectively) than the other legume species. It is concluded from these studies that L corniculatus is suited to marginal or free‐draining calcareous soils under low‐input conditions, and consequently has more potential for use in the UK than has previously been reported.
Leaf appearance and senescence patterns of some pasture species
Authors: CALVIERE I. , DURU M. 
Published: April 2006

AbstractFive pasture species, very different in their morphological organization (four dicotyledons: Plantago lanceolata, Sanguisorba minor, Ranunculus repens, Taraxacum officinalis and one grass: Dactylis glomerata), were grown as spaced plants in pots, thus excluding competition for light, to study the proportion of senescent leaves. In May, after a 6 month period, the proportion of partially or totally senescent leaves varied from 20% to 80%. Four plant characteristics were important: leaf appearance and senescence rates, leaf lifespan and date and type of flowering. Plantago lanceolata had the longest lived foliage and the smallest proportion of senescent leaves. In contrast, Taraxacum officinalis had the most rapid leaf turnover and Dactylis glomerata had the slowest rate of leaf appearance. Sanguisorba minor and Ranunculus repens were almost identical, with intermediate leaf characteristics in all respects. These results illustrate the fact that the four characteristics studied, and not simply the species' phenology, must be taken into account in order to compare growth between species. The likelihood of these characteristics remaining the same when species are in dense sward is considered.
Effects of grazing by sheep or goats on sward composition in ryegrass/white clover pasture and on subsequent performance of weaned lambs
Authors: del POZO M. , WRIGHT I. A. , WHYTE T. K. , COLGROVE P. M. 
Published: April 2006

AbstractAn experiment was conducted to assess the effects of grazing a perennial ryegrass (Lolium perenne)/ white clover (Trifolium repens) sward by sheep or goats on sward composition and structure and on subsequent diet selection, herbage intake and liveweight gain by weaned lambs. From mid‐May to late July (phase 1), ewes with twin lambs or yearling Scottish Cashmere goats grazed continuously swards maintained at 4‐ or 8‐cm sward surface height. From mid‐August to the end of September (phase 2), weaned lambs continuously grazed the same swards maintained at 4 cm (treatment 4–4) or at 8 cm (treatment 8–8) or which had been allowed to increase from 4 cm to 8 cm (treatment 4–8). By the end of phase 1, swards grazed by goats had higher proportions of white clover in the whole sward (0.377 vs. 0.181; s.e.d 0.0382; P< 0.001) than those grazed by sheep, irrespective of sward height treatment. This resulted in phase 2 in a higher proportion of white clover selected (P<0.001), higher herbage intakes (P < 0.001) and higher liveweight gains (P < 0.001) by weaned lambs grazing swards previously grazed by goats compared with those previously grazed by sheep. There were higher proportions of clover present in the swards from treatment 4–8 at the beginning of phase 2 compared with the other sward height treatments and consequently weaned lambs had, on this treatment, a higher proportion of clover in their diet (P<0.001), higher herbage intakes (P<0001) and higher liveweight gains (P <0.001). It is concluded that goats can be integrated into sequential grazing systems with sheep on grass/clover swards and this can result in an increase in the proportion of clover in swards and increased sheep performance.
Effects of applying a bacterial inoculant to silage immediately before feeding on silage intake, digestibility, degradability and rumen volatile fatty acid concentrations in growing beef cattle
Authors: KEADY T. W. J. , STEEN R. W. J. 
Published: April 2006

AbstractIn an experiment, involving twelve male cattle (initially 235 kg live weight), the effects of applying lactic acid bacteria [Lactobacillus plantarum; 109 colony‐forming units (g fresh silage)−1] to grass silage, immediately prior to that silage being fed, on dry‐matter (DM) intake of the silage, degradability of nitrogen (N) and fibre in the rumen, total tract digestibility and composition of rumen fluid in the animals were examined. A grass silage, which had been made from the primary growth of a predominantly perennial ryegrass sward, was offered as the sole diet. The inoculant was applied to the silage at the rate of 2 g of freeze‐dried powder reconstituted in 12 ml of water (kg fresh silage)−1 immediately prior to that silage being fed and an equivalent amount of water was applied to the silage in the control treatment. The two diets were compared in a change‐over design. The silage was well preserved, having a pH and concentrations of ammonia N and butyrate of 3.72, 74 g (kg total N)−1 and 0.11 g (kg DM)−1 respectively. Application of the inoculant significantly increased true protein, acid‐insoluble N and water‐soluble carbohydrate concentrations (P < 0.001) in the diet. Silage DM intake was not significantly increased (P= 0.072) by this of inoculant treatment, which had no significant effect (P > 0.05) on rumen degradability or total tract digestibility of DM, N, neutral detergent fibre or modified acid detergent fibre. Rumen pH, ammonia concentration or the molar proportions of volatile fatty acids were not altered (P>0.05) by inoculant treatment. It is concluded that application of the inoculant to the silage prior to silage being fed did not significantly affect silage DM intake, total tract digestibility, or degradability or fermentation in the rumen of cattle offered grass silage as the sole diet. It is also concluded that the results of this experiment provide no evidence that the mode of action of L plantarum, applied as an additive to grass at ensiling in previous studies, is through ‘direct’ effects in the rumen.
An evaluation of the effects of rate of nitrogen fertilization of grassland on silage fermentation, in‐silo losses, effluent production and aerobic stability
Authors: KEADY T. W. J. , O'KIELY P. 
Published: April 2006

AbstractA factorial experiment was carried out to evaluate the effects of level of nitrogen (N) application to grassland and subsequent treatment of the herbage at ensiling with formic acid on the rate of silage fermentation, dry‐matter (DM) recovery, aerobic stability and effluent production. Herbage from the primary regrowth of predominantly perennial ryegrass swards received either 72 (LN), 126 (MN) or 180 (HN) kg N ha−1. The herbages were harvested and yield estimated after a 50‐day regrowth interval. After storage for 24 h in polythene bags, the herbages were ensiled, unwilled, in laboratory silos (6 kg capacity) either untreated (UT) or treated with formic acid (F) at 3 ml (kg herbage)−1. Three silos per treatment were opened and sampled on days 1, 3, 6, 15, 50 and 105 after ensiling. The mean herbage yields for the LN, MN and HN swards were 5.2, 6.3 and 6.2 (s.e. = 0.27) t DM ha−1 and there was no carryover effect of nitrogen treatment on the yield of a subsequent 22‐day regrowth harvested on 2 September. As level of fertilizer N application increased, concentrations in the herbage at mowing of crude protein, nitrate and ash increased, DM decreased and water‐soluble carbohydrate and in vitro DM digestibility remained unchanged. Increasing the rate of N fertilizer to the sward resulted in higher silage pH (P< 0.001) and ammonia N concentrations (P <0.001) at each time of sampling. Increasing the rate of fertilizer N increased effluent output (P < 0.001) and DM recovery (P < 0.001). Aerobic stability was improved (P <0.001) by use of high rates of N fertilizer application. Formic acid treatment restricted fermentation and increased effluent output (P <0.001) but had no effect (P > 0.05) on DM recovery. It is concluded that the rate and extent of pH decline was reduced with increasing N application, associated with increased buffering capacity and decreased DM concentrations of the herbage at ensiling. However, increasing the level of N fertilizer applied increased DM recovery and effluent output, and improved aerobic stability of the resulting silages.
Yield and quality of winter and spring triticales for forage and grain
Authors: ROYO C. , PARES D. 
Published: April 2006

AbstractIn field experiments conducted over 2 years in Mediterranean conditions, five winter and five spring triticales were evaluated for forage and grain production in the same cropping season. The experiments had two treatments, namely harvesting for grain only, and dual‐purpose forage and grain production. In the latter treatment, forage was cut when the first node was detectable (Zadoks' stage 31), without removing the apical meristems. Grain was harvested when ripe (Zadoks' stage 92) in both cut and uncut plots.Environmental conditions affected grain production and protein content more than forage yield and quality. Winter triticales yielded about 43% more forage than spring types, but after forage removal the spring types yielded about 36% more grain than winter triticales.Reductions in grain yield after clipping were more pronounced in winter (32%) than in spring (19%) types. Forage crude protein content was significantly higher in the spring types studied (24.6%) than in the winter types (23.5%), the opposite being true for fibre content (20.7 and 21.6% respectively). Grain crude protein content did not differ between grain and dual‐purpose treatments, but was higher in the spring triticales (12.8%) than in the winter types (11.9%). There was more variability for the measured traits within the winter triticales studied than within the spring types.
The effect of a high‐magnesium perennial ryegrass variety on the magnesium status of sheep
Authors: BINNIE R. C. , JOHNSTON D. T. , CHESTNUTT D. M. B. 
Published: April 2006

AbstractAn early‐heading variety of perennial ryegrass (Ramore) bred for high magnesium (Mg) content was compared with an early control variety (Frances) for its ability to increase Mg intake, Mg utilization and blood Mg concentration in sheep, and so reduce the incidence of hypomagnesaemic tetany. Swards of the two varieties were established and each was grazed by ewes suckling twin lambs from turn‐out to weaning and thereafter by dry ewes. In early and late season herbage from a proportion of each sward was cut daily and fed fresh to ewes housed indoors in metabolism crates.Under grazing conditions herbage from Ramore swards had, over the 1992 and 1993 grazing seasons, a higher Mg concentration than Frances (2.35 g kg−1 vs. 2.18 g kg−1; s.e.m. 0.019, P< 0.001). During the spring period there was a higher (P 0.001, s.e.m. 0.0074) Mg concentration in the blood of ewes grazing Ramore (0.854 m mol 1−l) swards compared with those grazing Frances (0.793 m mol 1 −1) whereas during the autumn period blood Mg concentrations were higher in ewes grazing Frances. Ewe and lamb liveweight gains, recorded in 1992 only, were higher on Ramore swards than on Frances swards, although the difference was not significant.Indoor feeding studies showed that Mg intake was significantly higher (P< 0.001, s.e.m. 0.026) in ewes offered Ramore (1.98 g d−1) herbage compared with those offered Frances (1.74 g d−1) herbage with no significant difference in dry‐matter intake between the two varieties. Apparent availability and retention of Mg were higher for animals fed Ramore during the spring feeding periods than those fed Frances, but during the autumn feeding periods the reverse was true. Under indoor feeding conditions, variety had no significant effect on blood Mg concentrations.It was concluded that under grazing conditions a high Mg variety could provide an effective means of reducing the incidence of hypomagnesaemic tetany.
Effects of continuous sheep stocking and strategic rest periods on the sward characteristics of binary perennial grass/white clover associations
Authors: GOODING R. F. , FRAME J. 
Published: April 2006

AbstractFive binary perennial grass/white clover (Trifolium repens, cv. Menna) mixtures were evaluated over a 3‐year period under continuous sheep stocking together with the imposition of a rest period for either an early or a late conservation cut; the experiment with plot sizes of 0·16 ha was replicated three times. The grass species and cultivars used were Merlinda tetraploid and Magella diploid perennial ryegrass (Lolium perenne), Prairial cocksfoot (Dactylis glomerata), Rossa meadow fescue (Festuca pratensis) and Goliath timothy (Phleum pratense). The greatest total lengths of white clover stolon developed in the meadow fescue (171·6 m m−2) and timothy (151·9 m m−2) associations compared with those in tetraploid perennial ryegrass (98·6 m m−2), diploid perennial ryegrass (91·9 m m−2) and cocksfoot (74·6 m m−2) (s.e.d. 16·4, P < 0·001). On average, the proportion of white clover stolon that was buried was between 0·86 and 0·89 and this was more abundant in late than early season. Whereas timothy persisted, the persistence of meadow fescue was low under any of the managements tested and this was markedly reduced by the third grazing season. In the diploid perennial ryegrass sward, a late June to early August rest period for conservation enhanced white clover stolon length. An early April to late May rest period greatly reduced total white clover stolon length in both diploid perennial ryegrass and tetraploid perennial ryegrass associations (diploid perennial ryegrass‐unrested 89 m m−2, early rest 56·1 m m−2, late rest 130·7 m m−2; tetraploid perennial ryegrass ‐ unrested 125·1 m m−2, early rest 71 m m−2, late rest 99·7 m m−2; s.e.d. 19·19, P < 0·001). The numbers of white clover stolon growing points per unit stolon length were greatest when the sward was rested during late June to early August −55·9 m−1 stolon length compared with 45·7 m−1 for an April to late May rest and 46 m−1 in the absence of a rest (s.e.d. 2·59, P < 0·001). Likewise, the percentage of stolon above ground was greatest with the late June to early August rest −15·78% compared with 10·61% for the April to late May rest and 7·69% for no rest (s.e.d. 1·569, P < 0·001). The complementary percentages of buried stolon indicate the important role this fraction has and the need to study stolon behaviour in grazing studies generally. It is concluded that, in relation to perennial ryegrass as a companion grass, meadow fescue and timothy allow better white clover development and cocksfoot less. However, other attributes have to be considered, for example the poor persistence of meadow fescue and the slower regrowth of timothy, both of which allow the invasion of weed grasses, or the lower acceptability of cocksfoot to livestock. The timing of the rest period before the conservation cut can influence white clover development considerably, but the effects differed with different companion grasses.