bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mineral composition of red clover treated with growth regulators in early spring
Authors: NARASIMHALU P. , KUNELIUS H. T. 
Published: April 2006

AbstractThe effect of growth regulators on mineral composition of red clover (Trifolium pratense L.) was assessed in two growing seasons, daminozide {butanedioic acid [mono(2,2‐dimethylhydrazide)]} or mefluidide [N‐(2,4‐dimethyl‐5{[(trifluoro‐methyl)sulphonyl]amino} phenyl) acetamide]] was applied early (mid‐May) or late (late May) at low rate [daminozide, 4 kg active ingredient (a.i.) ha−1; or mefluidide, 0·13 kg a.i. ha−1] or twice the low rate (high rate) to an early‐flowering cultivar, Florex, and a late‐flowering cultivar, Altaswede; the controls were the untreated cultivars. Red clover was deficient in S, but all other minerals were present in sufficient amounts for productive cattle. The first cutting showed increases in P and Zn contents after an early application of daminozide, Cu was increased when the high rate of daminozide was applied early, and Ca, Cu, K and Mg were increased when mefluidide was applied early or at the high rate. There were no interactions between daminozide and cultivar in terms of minerals, but mefluidide treatment increased Mg in Altaswede only. Altaswede showed a narrower N/S ratio in the first cutting, and contained more P, K and Mg in both cuttings than did Florex. This study indicated that growth regulator application, particularly the early application of daininozide at the high rate, improved the mineral profile in red clover.
Effectiveness of cattle slurry as a sulphur source for grass cut for silage
Authors: LLOYD A. 
Published: April 2006

AbstractThree trials were carried out in separate years during 1987–89 to investigate the effectiveness of cattle slurry as a source of sulphur (S) for grass cut four times per year for silage. They were located on different areas of the same field in Dorset, UK, in an area known to be sulphur deficient for intensive grass production. Yields of dry matter and S off takes in response to sulphur in slurry were investigated and compared with those from gypsum treatments supplying 0–100 or 0–75kg S ha−1. Slurry was applied at two times of year, November or February, and at two rates, either alone or in combination with the two lowest rates of gypsum.Annual increases in yield from the slurry applied in February compared with the yield when no slurry was applied were significantly related (r2= 0·96) to the rate of slurry sulphur applied. For applications in November, the relationship was not significant. Sulphur in slurry increased annual dry‐matter yield with an average efficiency of 55% when compared with the sulphur in gypsum. The annual apparent recovery in the herbage of S from slurry was 21·8%, compared with 44·7% from the two lowest rates of gypsum.Cattle slurry, in these and other trials in southwest England, contained on average 0·35 kg S m−3 and, at rates currently applied in farming practice or likely to be applied in the future, would be insufficient to satisfy annual requirements for silage in sulphur‐deficient areas.
Cell wall composition and degradability of stem tissue from lucerne divergently selected for lignin and in vitro dry‐matter disappearance
Authors: JUNG H. G. , SMITH R. R. , ENDRES C. S. 
Published: April 2006

AbstractLucerne populations that had previously been divergently selected for acid detergent lignin (ADL) concentrations of whole herbage were additionally divergently selected for in vitro dry‐matter disappearance (IVDMD) of basal stems. Parental plants of the four selected populations were intercrossed and the half‐sib progeny evaluated in a replicated field trial in 1988 over two harvests. Cell wall composition of basal stems was determined for detergent fibre components and neutral sugars, uronic acids, Klason lignin and esterified and etherified phenolic acids of the total fibre fraction. Lignin polymer composition was measured by nitrobenzene oxidation. Degradability of cell wall polysaccharide components was determined by a 48‐h in vitro ruminal fermentation. Cell wall composition was changed by both selection criteria. Klason lignin proportion of the total fibre did not differ as a result of selection, whereas the ADL concentration of neutral detergent fibre was different among selection groups. The cell wall polysaccharides of lucerne basal stems shifted towards more cellulose (glucose residues) and less hemicellulose (xylose residues) with selection for either low ADL or high IVDMD. While degradability of the cell wall polysaccharides was correlated with various measures of lignin composition and concentration, the results were variable and inconclusive. Surprisingly, Kiason lignin and ADL were positively correlated with cell wall polysaccharide degradability, and esterified ferulic acid was negatively correlated with degradation of the cell wall. Selection for herbage ADL and basal stem IVDMD of lucerne did alter cell wall degradation, but the associated changes in cell wall lignification were not consistently correlated with cell wall degradability.
Effect of nitrogen fertilization on herbage production of tall fescue swards continuously grazed by sheep. 2. Consumption and efficiency of herbage utilization
Authors: MAZZANTI A. , LEMAIRE G. 
Published: April 2006

AbstractThe effect of a reduced level of nitrogen fertilizer application upon the herbage consumption of a continuously grazed sward of tall fescue has been investigated during two successive years. Two contrasting cultivars were used and two levels of leaf area index were maintained on the swards in order to obtain a wide range of sward structure. The herbage growth, herbage senescence and herbage consumption were measured directly on labelled tillers. It was possible to estimate the different components of the defoliation process (frequency and intensity) at the level of individual tillers of each leaf category. The results show that the effect of reduction in N fertilizer on herbage consumption rate is proportionally more important than that on herbage growth rate. In consequence, the efficiency of herbage utilization in continuously grazed conditions is reduced when nitrogen nutrition becomes limiting for herbage growth. The data suggest that this phenomenon is not directly attributable to nitrogen deficiency but is an indirect effect owing to the reduction of the stocking density at the low N level, which leads to a lower frequency of defoliation of individual tillers.
The effects of management and plant variety on the composition, vertical structure and stock‐carrying capacity of Lolium perenne/Trifolium repens pastures
Authors: BARTHRAM G. T. , GRANT S. A. 
Published: April 2006

AbstractThe effects of sheep grazing, with or without a 7‐week rest period before ear emergence, on species balance in four perennial ryegrass/white clover swards were assessed.Swards of an early (Aurora) or a late (Melle) flowering ryegrass were grown with either a small‐leaved (Kent) or a medium‐leaved (Milkanova) clover.The clover lamina, expressed as a proportion of the total lamina mass, was greater with Kent than Milkanova. This proportion was not changed by resting the Aurora (earlier rest) swards, but was increased by resting the Melle (later rest) swards. A greater proportion of the clover lamina mass was near the top of the canopy in the Milkanova than in the Kent swards, and during the summer than in spring or autumn. The densities of clover growing points were greater in the Kent than the Milkanova swards and were increased by the late rest period. This effect persisted over the winter.Stocking density was higher on the Kent than the Milkanova swards. The effects of the two rest periods, and the variety combinations, on pasture composition are interpreted as being principally a result of the differences in temperature between the earlier and later rest periods and of the different relationships between temperature and the growth of ryegrass and clover. Varietal characteristics, such as the vertical distribution of laminae, were also shown to be important.
Rumen degradation and intestinal digestion of grass and clover at two maturity levels during the season in dairy cows
Authors: STEG A. , van STRAALEN W. M. , HINDLE V. A. , WENSINK W. A. , DOOPER F. M. H. , SCHILS R. L. M. 
Published: April 2006

AbstractA comparison was made of the effect of season and maturity on the in situ ruminal breakdown and intestinal protein digestion in dairy cows between intensively N‐fertilized grass (whole sward) and moderately N‐fertilized ryegrass and clover from a mixed sward. From May to September 1990, eight consecutive cuts were made, representing alternate harvests of late and early swards. Limited effects of fertilizer‐N on chemical and ruminal degradation characteristics and intestinal digestion of grasses were observed. Clover had higher ash, crude protein (CP) and lignin and lower hemicellulose, cellulose and sugar contents than grass. Moreover, soluble fractions of organic matter (OM) and CP were higher, and rumen‐undegradable OM and CP fractions were lower. Soluble fractions of grasses and clover decreased and undegradable fractions increased during the season. More mature swards showed increased undegradable fractions. Degradation rates of OM and CP in clover were, respectively, higher than or similar to those of grass. Seasonal effects on degradation rates differed between grass and clover. Effectively rumendegradable (g kg−1 DM) carbohydrates and CP, escaped protein and intestinal digestion of escaped protein were higher in clover than in grasses. Inclusion of clover in swards may result in higher post‐rumen protein supply. Supplementation of clover‐based diets is suggested to compensate for an increased loss of N in the rumen.
The effect of grass plant size on basal frequency estimates
Authors: COOK J. W. , BRADY W. W. , ALDON E. F. 
Published: April 2006

AbstractFrequency data from different‐sized plots are generally accepted as being incomparable. However, how basal frequency data are influenced by plant basal diameter is not well known. Computer simulations were used to determine the influences of grass plant basal diameter on basal frequency data. Basal frequency, basal area and density were estimated with simulated 5 × 10 cm and 20 × 50 cm rectangular plots. Simulated plants had basal diameters ranging from 1.9 to 12.7 cm.Basal diameter had a significant effect on the relationship between frequency and both basal area and density. As differences in plant size increase, the effect on basal frequency becomes larger and the likelihood of an ecologically important influence also increases. Thus, frequency data should not be used to compare relative abundance of species, unless corrections are made for differences in plant basal diameter among species. Additionally, frequency data should not be used to monitor change in abundance of a species through time, unless mean plant basal diameter can be assumed to remain relatively constant.Basal frequency data could be used to ‘signal’ when change has occurred. Then, other sampling methods must be used to determine the nature and direction of change or relative species abundance. For frequency data, the simplicity of collection may be offset by difficulty in interpretation.
Aerobic deterioration of grass silage: the need to couple models and experiments
Authors: RUXTON G. D. , GIBSON G. J. 
Published: April 2006

AbstractA mathematical model of the aerobic stability of grass silage is presented. The model is shown to predict as well as more complex models previously published. Sensitivity analysis performed on model parameters suggests that current understanding of the temperature dependence of yeast growth needs to be advanced in order to produce more accurate models of deterioration. Inhibition of yeast growth by organic acids is identified as a critical process worthy of further investigation. We discuss how model validation experiments must identify different yeast species and track their growth separately. Such experiments should also attempt to minimize or measure heat losses.
A note on the behavioural strategies used by grazing animals to alter their intake rates
Authors: NEWMAN J. A. , PARSONS A. J. , PENNING P. D. 
Published: April 2006

AbstractA large, and often neglected, component of grazing intake is behavioural. Grazing animals may employ two strategies to increase their intake rates during grazing: increasing bite mass and decreasing handling time. These strategies are discussed in the context of fasted and non‐fasted sheep grazing white clover (Trifolium repens L. cv. Kent wild white) and perennial ryegrass (Lolium perenne L. cv. Parcour). It is concluded that within a forage species sheep have little flexibility for increasing their intake rates by altering their handling times but have some latitude for altering bite masses. Between forage species, differences in intake rates may be more strongly affected by the ‘species‐specific’ requirement for mastication than by differences in bite masses per se. Comparisons are also made with grazing strategies of cattle.
The effect of blending white clover varieties and their contribution to a mixed grass/clover sward under continuous sheep stocking
Authors: EVANS D. R. , WILLIAMS T. A. , JONES S. , EVANS S. A. 
Published: April 2006

AbstractThe effect of blending small‐ and medium‐leaved white clovers together in a mixture of varieties was examined under continuous sheep stocking over a period of three years. Four varieties were used, S184 and Gwenda, small‐leaved varieties suitable for intensive sheep grazing, together with medium leaved varieties Menna and Donna, which are mainly used in general purpose seed mixtures for medium term leys. The small‐leaved varieties were blended with Menna or Donna, sown with a commercial grass mixture and managed as near as possible to farm practice. Although the leaf size of Gwenda is only slightly greater than that of S184, blends based on these two small‐leaved varieties behaved differently. In spring of the first harvest year the yield of Gwenda and of the clover in mixtures containing Gwenda was 27% greater than the yield of the same mixtures which contained S184. As the season progressed this difference decreased. In terms of total annual yields and saving in fertilizer N, the benefits of including white clover in a seed mixture were more pronounced when Menna was mixed with S184 and Gwenda, rather than when Donna was used, although both varieties are in the medium‐leaf category. It was concluded that the slower establishment and the lower clover yield of S184, when compared with larger leaved varieties, can be overcome by blending with a variety that is slightly larger in leaf size, such as Menna, although the choice of variety may depend on sward management and its persistency under grazing.
Herbage intake and N excretion by sheep grazing monocultures or a mixture of grass and white clover
Authors: ORR R. J. , PENNING P. D. , PARSONS A. J. , CHAMPION R. A. 
Published: April 2006

AbstractIn 1988 and 1989, swards of grass (G0), while clover (C0) and grass/white clover (GC0) receiving no N fertilizer, and a grass sward supplied with 420 kg N ha−1 (G420), were grazed by non‐lactating sheep to maintain a sward surface height of 6 cm. Herbage organic matter (OM) intakes averaged between 1200 and 1700 g OM ewe−1 d−1. For treatments G0, C0, GC0 and G420 respectively, the ewes' live weight gain was 102, 112, 100 and 110 g d−1 and changes in body condition scores were +0·28, +0·52, +0·36 and +0·44 units season−1. However, the effect of treatment was not significant for either variable. There were similar levels of output of faecal N ewe−1 but significantly more urinary N ewe−1 was excreted on treatments C0 and G420, where the concentrations of N in herbage laminae were also higher. For example, in 1989, total daily N excreted was 39·7, 64·4, 44·0 and 63·3 g N ewe−1 for G0, C0, GC0 and G420 respectively. Taking into account the mean daily stocking rates, which were 19·4, 26·6, 27·2 and 36·5 ewe ha−1, the total faeces and urine returns over the season were 161, 358, 249 and 484 kg N ha−1 for each treatment respectively. The herbage OM intakes ewes−1 d−1 measured in September and October were similar for C0 and G420, and so the intake of herbage OM ha−1 d−1 was related to stocking rate, i. e. the estimated herbage intake ha−1 over the growing season for the white clover monoculture was 73% of that for N‐fertilized grass. Excretal nitrogen returns to the pasture from grazed mono‐cultures of clover were high, and similar to those from a grass sward receiving 420 kg fertilizer N ha−1. Consequently potential losses of N to the environment are high under these management systems.
Interactions between variety and the timing of conservation cuts on species balance in Lolium perenne‐Trifolium repens swards
Authors: BARTHRAM G. T. , GRANT S. A. 
Published: April 2006

AbstractThe effects of two periods of rest from grazing by sheep (either April‐May or May‐June) on the composition of swards of both an early‐flowering (Aurora) and a late‐flowering (Melle) perennial ryegrass variety grown with cither a small‐leaved (Kent) or a medium‐leaved (Milkanova) white clover variety are described. Compared with a continuously stocked treatment, the early rest period did not affect the mass of clover in the swards (expressed as a proportion of the total) but resulted in a subsequent decrease in its population density. The late rest period doubled clover mass in the swards at the time of cutting but did not affect the subsequent population density of clover. The magnitude of the change in mass during the late rest period depended on ryegrass variety, but not on clover variety. The adverse effect of the early rest period on the subsequent population density of clover was associated with the degree of shading experienced by clover laminae at the end of the rest period. Temperature may also have had an effect here as mean temperatures were cooler during the early rest period than during the late rest period. It is concluded that the effects of the two rest periods on the clover content of the swards were primarily due to timing, and less to inherent differences between ryegrass varieties.
Negative effects of winter‐ and spring‐applied cattle slurry on the yield of herbage at simulated early grazing and first‐cut silage
Authors: SMITH K. A. , JACKSON D. R. , UNWIN R. J. , BAILEY G. , HODGSON I. 
Published: April 2006

AbstractExperiments were earned out on seven UK sites during 1985–1988 to evaluate the importance of negative effects (smoethering and scorch) of winter and spring‐applied cattle slurry on grass yield, assessed at the time of early grazing or first‐cut silage. Slurry application has both positive and negative effects on herbage growth. Positive effects, usually associated with herbage yield increases, derive from the nutrient value of the slurry. Negative effects, often resulting in herbage yield decreases, are caused by smothering and/or scorch. The net effect on herbage depends on the balance between these positive and negative effects. These experiments were designed to isolate the negative effects of slurry whilst attempting to minimize the positive effects. Yield reductions of up to 20% for early grazing and 5% for first‐cut silage were recorded, following applications of cattle slurry in February and March. Earlier applications smaller yield reductions. The threshold for the occurrence of yield reduction was estimated at 3–4 t ha−1 of slurry solids applied, at 6% solids content. In practice this would mean an application of 50–65 m3 ha−1 at 6% dry matter, which would supply 150–200 kg ha−1 total nitrogen, based on typical slurry analyses. Within the limits of application rates tested in these experiments, yield depression tended to increase with increasing rate of slurry applied above this threshold. Although the results suggest that the effects are more likely to occur following spring applications of slurry, earlier (autumn or winter) applications would increase the risk of losses of slurry nitrogen by leaching and denitrification. These results, therefore, confirm current advice in the UK that, where possible, cattle slurry is best applied to grassland in early spring according to the fertilizer needs of the crop. High rates of application should be avoided after early March for cutting areas and, more especially, for early grazing.
Animal production evaluation of herbage varieties.
Authors: DAVIES D. A. , FOTHERGILL M. , DANIEL G. J. , MORGAN C. T. 
Published: April 2006

AbstractPerennial ryegrass/white clover (Lolium perennel Trifolium repens) pastures of three white clover varieties were compared at UK lowland (Plas Gogerddan, PG) and upland (Bronydd Mawr, BM) sites over three harvest years (1989–91) under continuous variable stocking (ewes and lambs until weaning and lambs thereafter). Mean annual lamb output from small‐leaved S 184 (1179 kg ha−1) was 29% greater than that from prostrate small‐leaved AberEndura at PG with medium‐leaved Huia also giving 19% more output than AberEndura. At BM, output from S 184 (863 kg ha−1) was 19 and 14% greater than that from AberEndura and Huia respectively. The differences in lamb output between the small‐leaved varieties owed to a combined effect of higher individual lamb growth rates and greater stock‐carrying capacity, both of which were more pronounced in the post‐weaning period. The higher output from S 184 relative to Huia at BM was attributed to higher stocking rate, particularly after weaning. Clover productivity and persistence were also studied under three cutting‐only managements at PG. Performance under a treatment cut at 2–3 cm every 10 d (T1), which is synonymous with assessment of persistence in UK National List testing, was poor with clover growing point number of only 498 m−2 compared with 4906 m−2 on the grazed sward in autumn 1991. Although productivity and clover content under T3 (cut at 3–4 cm every 42 d — similar to National List yield regime) gave the same varietal ranking as lamb production, there was an under‐estimation of the small‐leaved varieties, particularly AberEndura, relative to Huia. An intermediate treatment (T2), cut at 3–4 cm every 21 d, also over‐estimated the performance of the medium‐leaved variety. Herbage data from ground level sampling every 21 d using exclosure cages on the grazed swards were also poorly related to lamb performance. These results highlight the effect of clover variety on lamb production, which appeared to be independent of leaf size, and also confirm the existing problems associated with assessment of white clover varieties using a cutting regime.