bluuebunny/crossref_metadata_2025 huggingface dataset:
THE INFLUENCE OF PHOSPHATE AND LIME ON THE GROWTH AND N FIXATION OF LOTUS ULIGINOSUS AND TRIFOLIUM REPENS UNDER GREENHOUSE CONDITIONS
Authors: Gibson, P. Hayes D. I. , Laidlaw A. S.
Published: April 2006

Shoot dry weight, leaf area, leaf lamina dry weight and N‐fixation of L. uliginosus cv. Grasslands 4705 were compared with those of T. repens S184 over a 90‐day period frotn sowing, in pots in a greenhouse. Three P and three pH levels were imposed and there were three destructive harvests at 30‐day intervals. N‐fixation was estimated by the acetylene reduction technique prior to the last harvest. L. uliginosus had higjier means than T. repens for all characters measured under all treatments at all harvests. Large increases in shoot weight and leaf area were associated with addition of P, particularly with the first increment of P to L. uliginosus. High P reduced the contribution of lamina to total shoot weight in T. repens more than in L. uliginosus at the second harvest. Raising pH increased shoot weight and leaf area in both species.

N‐fixation was low in both species at low pH and low P. This was increased by addition of P, a smaller quantity being necessary for the same response in L. uliginosus compared with T. repens. At the higher P levels, the high pH gave rise to lower N‐fixation than at the medium pH.

Results are discussed in relation to field trials of other workers and the possible suitability of L. uliginosus for low fertility upland conditions.
THE CONSUMPTION OF PERENNIAL RYEGRASS AND RED CLOVER BY GRAZING LAMBS
Authors: Hodgson J.
Published: April 2006

Groups of six‐month old lambs, which were either experienced or inexperienced grazers, strip‐grazed swards of S24 perennial ryegrass or Hungaropoly tetraploid red clover, at daily herbage allowances of 20 or 40 g OM/kg LW, in late August and September. The swards were similar in N content, but the weight of standing crop, and its digestibility, were higher on grass than on clover. Estimates of herbage intake were made in two successive periods of 19 days. Intake (g OM/kg LW) was lower at low than at high allowance (by 22% and 28% in periods I and II). and experienced grazers ate more than inexperienced animals (by 27% and 22%). Intakes on clover were 28% higher than on grass in Period I, but in Period II the difference was not significant.
THE EFFECT OF NITROGEN APPLICATION AND AUTUMN MANAGEMENT ON AUTUMN GROWTH, WINTER ‘BURN’ AND SPRING GROWTH OF LOLIUM PERENNE L. AT ABERYSTWYTH, EDINBURGH AND CAMBRIDGE.
Authors: Charles A. H. , England F. , Thomson A. J.
Published: April 2006

A trial was carried out to find management practices which would permit the best discrimination for winter performance of erennial ryegrass cultivars. Due to the mild winter experienced only a few of the plants were killed outright. The cultivars were therefore assessed for percentage of green herbage and for spring growth.

There were four sites: an upland and lowland site at Aberystwyth and one site each at Edinburgh and Cambridge. At all sites two N rates (totals of 125 or 550 kg/ha in the first year after sowing) and 5 autumn cutting treatments were used to give differences in the amounts of herbage remaining at the onset of winter. The last dates of defoliation in the autumn were: C1 end of August; C2 end of September; C3 end of October; C4 mid‐November; C5 was cut on all these dates. Four cultivars (Grasslands Ruanui, S321, Premo and Argo) which differed in their autumn growth potential, frost susceptibility and degree of winter dormancy were grown.

The autumn yield of S321 was, in general, higher than that of the other cultivars but there were interactions with N, management and location. The data on percentage of herbage remaining green in February illustrated differences due to the siting of the trial. In the conditions prevailing the two Aberystwyth sites facilitated greater discrimination between cultivars than those at Edinburgh and Cambridge.

In three of the four sites the management which produced most winter ‘burn’(including both that due to natural senescence and that due to winter damage) involved accumulation of herbage in the autumn but there were considerable sites × managements interactions. For example at Cambridge management produced no significant effect whereas at the Aberystwyth lowland site frequent defoliation in the autumn had more effect than allowing herbage to remain uncut after the end of August. High N significantly decreased the percentage of green herbage only at the two Aberystwyth sites.

Over five‐fold differences in spring yield were obtained, the heaviest yields being recorded at Edinburgh and Cambridge. However, there were large interactions between environments and cultivars; for example the higher N rate reduced spring yield at Aberystwyth but increased spring yield at Edinburgh and Cambridge. Premo and S321 had similar yields in spring at the Aberystwyth lowland and Cambridge sites but Premo was higher yielding than S321 at the Aberystwyth upland site and at Edinburgh.

The large environmental effects and their interactions with cultivars illustrate the difficulties of cultivar assessment and the dangers inherent in national recommendations for grass cultivars.
Effect of concentrate, dried grass and dried white clover ratios on intake, digestibility and liveweight gain by early‐weaned lambs
Authors: MARSH R. , Chestnutt D. M. B.
Published: April 2006

Early‐weaned lambs were offered rations of conventional concentrate, dried grass and dried white clover pellets ad libitum for 52 days. In vivo OM digestibility coefficients of concentrate, grass and clover were 80.0, 53.4 and 66.6% respectively. Dry matter intake of dried grass was similar to that of concentrates but supported significantly lower (P < 0.001) daily gains (0.18 kg). Supplementation of dried grass with an equal proportion of dried clover significantly increased (P <0.05) DM and DOM intake and daily gains. Daily gains by lambs offered the 1:1 grass:clover diet (0.29 kg) were similar to gains by lambs offered either dried clover (0.30 kg) or concentrates (0.30 kg).
Digestion in the stomach and intestines of sheep receiving diets of red clover silage with various supplements
Authors: THOMAS P. C. , CHAMBERLAIN D. G. , ALWASH A. H.
Published: April 2006

Three castrated male sheep fitted with rumen and duodenal re‐entrant cannulae were used in a 3×3 Latin Square experiment to investigate the digestion of three diets of red clover silage with supplementary concentrates containing barley or barley and groundnut meal or barley and urea. The supplements were designed to be isocaloric and the groundnut meal and barley‐urea mixtures to be isonitrogenous.

There were no significant (P >0.05) differences between treatments in the digestibility of organic matter (mean value 71.2%) or in the percentage of dietary organic matter digested in the stomach (mean value 53.6%) and diiferences between treatments in the concentrations of total and individual short‐chain fatty acids in the rumen were small. The nitrogen intake for the barley treatment was 19.41 g/d and that for the groundnut meal and barley‐urea treatments were 23.36 g/d and 23.05 g/d respectively. Corresponding figures for the duodenal flows of nitrogen were 21.97 g/d, 21.48 g/d and 21.14 g/d and for the faecal losses of nitrogen were 7.09 g/d, 6.98 g/d and 6.92 g/d. As a consequence, although the diets supplied quite different amounts of digestible crude protein they supplied similar amounts of crude protein digested in the intestines.
The size of the root system of tetraploid red clover and its relation to the chemical composition of the herbage produced
Authors: CHLOUPEK O.
Published: April 2006

The size of the root system was measured by means of electrical capacitance in relation to the soil in field experiments with three varieties of tetraploid red clover over a period of 3 years. The root system was greatest in the first year, smaller in the second year and least in the third year. The plants that gave an above‐average yield in any cut always had above average‐sized root systems in the preceding period, but usually after cutting, the size of their root systems decreased, an effect which was accentuated by plants drying out. The plants that dried out during the experimental period always had below average‐sized root systems in preceding periods. It was found in four cuts that the herbage dry matter of the plants with larger roots contained a smaller proportion of nitrogenous materials and ash, and more fibre, but the yield of all measured nutrients and elements increased. The ash of the herbage DM of these plants contained more potassium, calcium and magnesium. The quantity of mineral materials absorbed per unit of size of root systems was higher in the plants with larger root systems.
The effect of delayed autumn harvest on the survival of varieties of perennial ryegrass
Authors: HUNT I. V. , FRAME J. , HARKESS R. D.
Published: April 2006

The reactions of five early and five late varieties of perennial ryegrass to stimulation of bulky autumn growth and deferment of harvesting were compared in terms of spring growth and subsequent recovery during three winters.

Winterkill was marked in 1971–72, particularly when harvesting was deferred to late November, in early varieties S24 and Presto Pajbjerg and in the late variety S23. Least affected among early varieties were Premo and Barvestra (tetraploid) and among late varieties, Perma and Barpastra (tetraploid). All varieties showed rapid recovery.

The results are discussed in terms of the significance of winterkill, and the effects of age of sward, variety susceptibility and deferment of autumn defoliation. It is concluded that the form of winterkill which occurs in the west of Scotland can have serious consequences to farm productivity in severe winters. Autumn growth left standing into November can also lead to winterkill.

Under good management, varietal differences are unimportant. In a severe winter, no varieties of perennial ryegrass are reliable.
Effect of nitrogenous fertilizer on production per animal and per unit area by beef cattle offered similar daily allowances of herbage
Authors: MARSH R.
Published: April 2006

An experiment repeated in 3 consecutive years in which 0, 200, 400 and 600 kg ha−1 fertilizer N was applied annually is described. Cattle on all treatments were offered the same constant daily amount of 2.0 kg herbage DM per 100 kg liveweight above a 3.4 cm height of defoliation. Digestible OM intakes and daily rates of gain were in general not significantly different between treatments. Area required to support these intakes and gains however differed significantly between treatments (P < 0.001) and resulted in high outputs of liveweight gain per hectare on all treatments when compared with other published studies. These outputs together with other actual and theoretical outputs were used to predict optimum fertilizer N applications for grazing beef cattle and the predictions discussed in relation to commercial practice.
The effect of method of treatment with petroleum ether on the drying rate of grass leaves measured in the laboratory
Authors: HARRIS C. E.
Published: April 2006

Excised S24 perennial ryegrass leaves were dried in controlled and measured conditions of temperature (28°C), relative humidity (22%) and airspeed (40 cm s−1), without treatment or after treatment with petroleum ether (4O–60°C boiling point) applied in various ways. Subsequent increase in the drying rate of the leaves varied greatly with method of application of petroleum ether, and the results indicate that the modification of the waxes on the leaf surfaces, which results in reduced cuticular resistance to water loss, requires the presence of liquid petroleum ether on the leaf surface. This effect increases with temperature, and the increase is due to the enhanced activity of the petroleum ether in dissolving waxes, rather than to direct thermal effect on tissue resistance. The practical implications of employing such a technique are discussed.
The effect of an additive containing non‐protein nitrogen on some fermentation characteristics of maize silage
Authors: PHIPPS R. H. , FULFORD ROSEMARY J.
Published: April 2006

A non‐protein nitrogen additive containing ammonia, molasses and minerals was applied to precision‐chopped forage maize to raise the crude protein content of the ensiled crop from approximately 8% to 10, 14 or 16%.

The dry matter content, total nitrogen, water‐insoluble nitrogen, and water‐soluble nitrogen concentrations were measured at ensiling and 2 and 8 weeks later. The pH and lactic, acetic, propionic and butyric acid contents of the resultant silage were determined 2 and 8 weeks after ensiling.

The levels of crude protein achieved were 10.8, 11.5 and 14.2%, which are equivalent to recoveries in the silages of 108, 82 and 89% of the applied nitrogen. After 8 weeks the water‐insoluble nitrogen content of the treated silages had increased while the water‐soluble nitrogen content had decreased. The increase in water‐insoluble nitrogen may have been due to either decreased proteolysis or increased levels of microbial protein.

There was a significant increase of 0.6 units in the pH of the silage when comparing the control to the highest rate of additive application. The additive increased the levels of lactic and acetic acid in the maize silage.
The intake of maize silage by self‐fed heifers allowed restricted access
Authors: LEAVER J. D. , YARROW N. H.
Published: April 2006

The intake of maize silage by self‐fed heifers was measured where access to the silage was limited either by reducing the width of the feed face or by restricting the time allowed for feeding. In the first experiment twenty heifers were allowed 0.4 or 0.2 m feed face per head for 7 h daily. In the second experiment fourteen heifers were allowed 0.5 m feed face per head for 5 or 3 h daily. Intake was measured either by estimating faecal output by the chromic oxide technique and then using the in vitro estimate of silage digestibility to calculate individual intakes, or by using the results of eight individually fed heifers to provide a direct relationship between the chromic oxide concentration of the faeces and total intake, and using this to predict the intake of the self‐fed heifers from the concentration of chromic oxide in their faeces. The latter method was found to be the most satisfactory because it took into account the effect of level of feeding on the digestibility of maize silage. Restriction of access to the silage by limiting feed face width (Experiment 1) and time (Experiment 2) significantly reduced intakes by 4 and 7% respectively. In both experiments feeding time was significantly reduced by restriction, but this was partially compensated for by a significant increase in rate of eating.
The effect of urea on the voluntary intake by calves of silages preserved with formaldehyde and formic acid
Authors: LONSDALE C. R. , THOMAS C. , HAINES M. J.
Published: April 2006

Perennial ryegrass cv. S23 was preserved by fermentation (C), or with the addition of 8.7 1 formalin (35% w/w formaldehyde) per t fresh herbage (F) or of 9.0 1 equal mixture (by vol.) of formalin and formic acid (85% w/w solution) per t fresh herbage (FF). These three silages comprised the treatments in a three‐period, crossover design in which urea (u) was given at the rate of 20 g per kg dietary DM to half the animals. Twelve calves were allocated to the treatment sequences when they were approximately 12 weeks of age from within groups which had previously received diets with or without urea.

Calves ate significantly (P< 0.001) less of silages F or FF than of silage C when each was offered alone, but when urea was given, intakes of silages F and FF were significantly (P < 0.001) increased such that the intakes of all three silages with urea were similar (23.6, 19.6, 19.3, 24.2, 24.2, 24.7 ± 0.51 g DM per kg LW for C, F, FF, Cu, Fu and FFu, respectively). Significantly (P<0.01) more of the DM in silage C was digested than in F or FF and the addition of urea significantly (P<0.05) increased the digestibility of DM from silage FF only (73.8, 71.3, 69.8, 74.6, 70.7, 72.5 ± 0.72% for C, F, FF, Cu, Fu and FFu, respectively). When the silages were given alone, calves spent longer eating and ruminating per kg DM ingested with F or FF than with C. The time spent on F and FF was significantly (P<0.01) reduced by the addition of urea (303, 388, 411, 297, 299, 290 ± 18.9 min per kg DM ingested for C, F, FF, Cu and Fu and FFu, respectively).

The results presented suggest that urea partially alleviated the reduction in voluntary intake by calves given herbage preserved using formalin, but the mode of action was not clear.
A comparison of Italian ryegrass (Lolium multiflorum), hybrid ryegrass (Lolium perenne × L. multiflorum) and timothy (Phleum pratense) under different systems of management
Authors: SWIFT G.
Published: April 2006

An Italian ryegrass (cv. RvP), a tetraploid hybrid ryegrass (Sabrina), and an early heading timothy (Scots), were compared under 3‐cut silage plus aftermath, 5‐cut early bite‐hay‐aftermath and 6‐cut simulated grazing managements over 2 harvest years 1974–75. Annual nitrogen applications totalled 375 kg ha−1 N for the silage and grazing systems and 325 kg ha−1 for the early bite‐hay‐aftermath treatment.

In 1974, the first harvest year, RvP and Sabrina outyielded Scots timothy. In the dry summer of 1975 the drought tolerance and persistency of Sabrina was superior to RvP, but both grasses gave low yields (approx. 10·0 ha−1 DM under the conservation managements) and showed a marked fall in production compared with the first year, by RvP of 35% and by Sabrina of 25%. Scots timothy in the second year equalled the ryegrass in total DM yield under the hay management system. Over the 2 years RvP and Sabrina gave similar yields, which were 10% better than Scots timothy, under all managements.

RvP and Sabrina are equally suitable for silage production, but second and third silage cuts of RvP require shorter regrowth periods than Sabrina for good quality herbage. Sabrina will also provide leafier grazing than RvP.
The effects of dalapon and stocking rate on the species composition and animal productivity of a sown sward
Authors: HAGGAR R. J. , ELLIOTT J. G.
Published: April 2006

Dalapon (2.8 kg ha×1) was applied in July, either annually or biennially, to a sown sward that contained about 50%Lolium perenne measured on a ground cover basis. The sward was grazed with young beef animals at three stocking rates throughout the 4 years of the experiment.

In unsprayed plots, the proportion of L. perenne declined to less than 20% (30, 14 and 16% on high, medium and low stocking rates respectively). Lolium perenne was replaced largely by Holcus lanatus and Poa spp. Annual applications of dalapon checked the decline in L. perenne. After 4 years of annual treatment with dalapon, 44%L. perenne was present on heavily stocked plots, 41% on medium stocked plots and 26% on lightly stocked plots. Biennial applications of dalapon had slightly less effect on the proportion of L. perenne. The proportion of Trifolium repens in the sward was affected by dalapon and stocking rate in much the same way as that of L. perenne.

Monthly cattle weights showed that dalapon caused a slight check to individual animal performance in the month after spraying, but total liveweight gain per unit area was not significantly affected. Increasing stocking rates were inversely related to performance per animal and directly related to output per unit area. Dalapon × stocking rate interactions were generally non‐significant. There was a slight tendency for higher animal gains to be associated with higher proportions of L. perenne, but this only held for the first half of the growing season. Mean maximum liveweight gain of about 1000 kg ha−1 was achieved in 1974, by which time the proportion of Holcus lanatus had risen to a mean value of nearly 40%. The value of indigenous grasses for summer beef production is discussed.
The performance of beef animals on a permanent pasture*
Authors: ELLIOTT J. G. , DALE R. J. , BARNES F.
Published: April 2006

Between 1967 and 1975, 416 beef animals were grazed rotationally on an indigenous pasture (11.65 ha) containing Festuca rubra, Holcus lanatus, Poa trivialis and Agrostis spp. and dicotyledonous plants, but little Lolium perenne or Trifolium repens. Part of the land received fertilizer nitrogen at rates varying between 120 and 200 kg h−1 each year and part did not; some of the land was grazed only and some was cut and then grazed.

The winter gains of the animals (approx. 45 kg) were more variable and less than the summer gains (approx. 155 kg). Summer gain was inversely correlated with winter gain. An increase in initial weight of animals purchased from 1973 onwards did not increase either winter or summer gain. Friesians gained more than Hereford‐cross animals during the winter, but there was no difference in summer gain.

During 9 years the average animal weight per grazed ha in April was increased from 1260 to 2122 kg. The mean total gain on 1165 ha of grass was 6486 kg per annum in the first 3 years and 7266 kg per annum in the last 3 years. The average annual production was 590 kg live‐weight gain and 1.01 t hay or 2.33 t silage per ha. The output of fertilized grass in 1975 was calculated as 842 Livestock Unit Grazing Days (LUGD) per ha and that from unfertilized grass as 360 LUGD per ha. The overall output of utilized metabolizable energy in 1975 was 59–7 GJ h−1, with 69.3 GJ h−1 from fertilized grass and 29.8 GJ h−1 from unfertilized grass.
Predicting fertilizer interception by swards
Authors: HOULT E. H. , McGARITY J. W.
Published: April 2006

A method for determining the extent of fertilizer interception by plants is described. Regression models were developed from the data collected. Dry matter was found to be a convenient and satisfactory pasture parameter to use for the prediction of fertilizer interception.
The effect of grazing interval on the composition and productivity of a perennial ryegrass‐white clover sward
Authors: BETTS J. E. , NEWTON J. E. , WILDE RENÉE
Published: April 2006

A ryegrass‐white clover sward was grazed by Welsh Mountain ewes with single lambs at a stocking rate of nineteen ewes per ha from April until October. Rotational grazing was practised and the treatments compared were rest periods of 3, 4 or 5 weeks.

The percentage of ground covered by clover was estimated visually and quadrats were also cut to ground level to estimate the amount of clover dry matter present. A good correlation was obtained between these two estimates. Although the sward contained about 20% clover on visual assessment, the dry matter contribution was small.

The amount of clover increased slightly over the season on all treatments, but the different rest periods of 21, 28 and 35 d made no significant difference to the amount of clover present.

The growth rate of the lambs was also not significantly different between treatments.
Herbage growth, white clover content and lamb production on grazed ryegrass‐white clover swards
Authors: MARSH R. , LAIDLAW A. S.
Published: April 2006

Two contrasting Gremie perennial ryegrass and Blanca white clover seeds mixtures were established. Each sward type was either continuously or rotationally (four paddocks) grazed at two stocking rates by lambs of 26–28 kg initial mean live weight in two 12‐week experiments. Dry matter production, assessed by the cage method, was lower on the high‐clover sward during the first experiment but overall was similar between seeds mixtures. Clover content, and differences between sward types, declined with time and was lowered by continuous grazing in both experiments and by the higher stocking rate in the first experiment.

Animal performance was related to intake and both were increased by lowering stocking rate, increasing clover content and adopting a continuous grazing system. The results are discussed in relation to the experimental methods used and to other published findings.
Nitrogen and Italian ryegrass.
Authors: WILMAN D. , DALY M.
Published: April 2006

The regrowth of Italian ryegrass was studied at weekly intervals from 2 to 14 weeks after a cut in late April when 140 kg ha‐1 N was applied. Reduction in digestibility with delay in date of harvest was due to both an increase in the proportion of cell wall and a reduction in the digestibility of the cell wall, particularly the former from week 2 to about week 5 and particularly the latter after week 5. The reduction in the digestibility of the cell wall was about equally attributable to reduction in digestibility of cellulose and to reduction in digestibility of hemicellulose. The proportion of lignin in cell wall was highly correlated with both digestibility of cellulose and digestibility of hemicellulose. The proportion of digestible cell wall in dry matter was not as constant as has sometimes been noted, increasing by about 5 percentage units from week 2 to week 5 and decreasing by about 10 percentage units from week 5 to week 13. During the latter period the decline in digestible cell wall in dry matter accounted for nearly half the decline in true digestibility of dry matter. The ratio of cellulose:hemicellulose averaged 1:0.89 and hemicellulose was more digestible than cellulose. Rate of increase in yield of cell contents appeared to diminish from about the third week of regrowth onwards, whereas the rate of increase in yield of dry matter did not begin to diminish until about the seventh week. In vitro dry matter digestibility was not increased by adding extra N to the digestion tubes, even with samples containing only 1% N in dry matter.
Water, mineral and energy fluctuations in decomposing cattle dung pats
Authors: UNDERHAY V. H. S. , DICKINSON C. H.
Published: April 2006

Moisture and mineral concentrations and calorific values of cattle dung pats were studied under field conditions. The rate of moisture loss from dung pats varied according to the season but the dung was rarely re‐wetted by rainfall. Soluble mineral ions were only leached from pats by prolonged rainfall. Magnesium was particularly resistant to leaching. In the summer months about 15% of the organic matter in the dung was lost over 2 months. The calorific value of the dung decreased by 18% in the same period. The loss of organic matter resulted in a concentration effect in calcium, iron, magnesium and nitrogen.
Pre‐harvest desiccation of crops for conservation. 1. Effect of steam and formic acid on the moisture concentration of lucerne, ryegrass and tall fescue before and after cutting
Authors: TETLOW R. M. , FENLON J. S.
Published: April 2006

Five experiments were conducted to determine the effect of pre‐harvest treatment with steam or formic acid on the moisture concentration (MC) in crops of lucerne, two varieties of perennial ryegrass, tall fescue and Italian ryegrass. In each experiment, plots were treated with a mixture of hot gases and steam (S) or sprayed with an aqueous solution of formic acid (F). In the tall fescue experiment the F treatment was applied to the cut swath but in all other instances the F and S treatments were applied to the swards before cutting and the MC changes after treatment compared with those in untreated cut swaths (W 1). Twenty‐four hours after initial treatment all S plots, and those F plots other than tall fescue, were cut and the subsequent water loss compared with that from (i) untreated material cut at the same time (W 2) and (ii) the W 1 plots cut the previous day.

In all five experiments the change in the MC of the S plots was similar to that of the W 1 plots both before and after cutting. The reduction in the MC of the F plots before cutting was less than that of the S and W 1 plots, and in three of the five experiments water loss from cut F plots was apparently restricted in comparison with that from untreated cut material (W2).

Neither desiccant treatment showed great promise as a pre‐treatment to cutting for hay making although formic acid may have limited value when a crop is to be harvested directly for silage or artificial dehydration.

In an appendix, the efficacy of using accumulated vapour pressure deficit as a basis for comparing the water loss from the untreated cut crops drying under different conditions is demonstrated.
A. low‐cost, communal grazing design for preliminary evaluation of grazing systems
Authors: MICHALK D. L. , McFARLANE J. D.
Published: April 2006

A field design using a decagonal geometric shape is described which enables twenty small plots, each 0.08 ha in size, to be evaluated under communal grazing condilions. The decagonal design was compared with a conventional design using botanical composition and plant density as discriminating parameters. The results showed that communal grazing in the decagonal design gave similar botanical composition and plant density as the conventional design. Since less materials per treatment were used in the decagonal design, it offers a means of minimizing costs in preliminary screening experiments. However, since animal production cannot be monitored under communal grazing the most successful treatments would have to be further evaluated using the conventional approach.
The validity of in vitro techniques using rumen fluid or cellulase for predicting changes in the dry matter digestibility of grasses caused by fertilizer calcium, sulphur, phosphorus and nitrogen
Authors: REES M. C. , MINSON D. J.
Published: April 2006

Sixty‐four samples were used to measure the accuracy of in vitro techniques using rumen fluid‐pepsin or pepsin‐cellulase for predicting digestibility of grasses grown with different levels of fertilizer calcium(Ca), sulphur(S), phosphorus (P) and nitrogen (N). In each case, fertilizers changed in vivo dry matter digestibility (DMD) and the in vitro techniques accurately predicted the changes in in vivo DMD caused by fertilizer Ca, P and N. The in vitro techniques gave biased estimates of in vivo DMD in studies with fertilizer S. This bias was caused by a decrease in the digestive efficiency of the sheep when fed the unfertilized feed. It was concluded that biased estimates of DMD may be associated with low fertilizer levels and these cannot be eliminated by improving the in vitro techniques and would also apply to estimates of DMD based on chemical analysis of the feed.
Variations in composition of pasture herbage
Authors: THOMPSON J. K. , WARREN R. W.
Published: April 2006

Changes in the chemical composition of pasture samples from five dairy farms were observed over a 2‐year period. Many of the minerals were at their lowest concentration in samples taken in the spring and early summer. At these times the concentrations of P, Mg and Na were often less than sufficient to meet the calculated requirements of the dairy cow fed on pasture alone. Cu and Co concentrations in the herbage were also generally low relative to the needs of the dairy cow.
Survivor populations of S23 perennial ryegrass from zero‐grazed and set‐stocked swards
Authors: PIKE A. , McNEILLY T. , PUTWAIN P. D.
Published: April 2006

Perennial ryegrass tillers were collected from intensively used set‐stocked and zero‐grazed leys and from an old permanent pasture, grown on and compared at 30 cm spacing. All swards except the permanent pasture had been sown with cv. S23 and were of known age, ranging from 6 months to 11 years from sowing.

Each genotype was scored for date of inflorescence emergence, and subsequently in vitro dry matter digestibility (DMD), D‐value of green leaf and the ratio of leaf dry weight: stem dry weight were determined.

Both DMD and D‐value declined significantly in green leaf samples of populations from the older zero‐grazed swards but no significant changes were detected in populations from set‐stocked swards. In set‐stocked populations there was a shift towards later flowering.

In zero‐grazed populations there was a consistent increase in the amount of leaf relative to stem with the age of the sward from which the plants were sampled. The survivor plants were more prostrate and leafier and it is suggested that under zero grazing, where cutting was to a uniform height, plants of this form were less severely defoliated and thus at a selective advantage.
The effects of asulam, frond cutting and ground mineral phosphate on the yields of swards dominated by bracken [Pteridium aquilinum (L.) Kuhn]
Authors: WILLIAMS GARETH , FRASER DOUGLAS
Published: April 2006

Two methods were adopted of measuring sward output, following the prevention of bracken frond growth, with differing results. Accumulated growth estimation, corresponding to production under a system of open‐range grazing, showed that asulam used for frond control had no effect on herbage yield in the year of application and large increases were observed in succeeding years compared with untreated control plots. In measuring production by sward regrowth after cutting, corresponding to intensive pasture utilization systems, asulam reduced yields in the year of treatment and increases were not observed until 2 years later. The inhibition of growth could be overcome by applying ground mineral phosphate at rates of 300 or 500 kg ha‐1 before spraying but the 500 kg ha‐1 rate showed no advantage over 300 kg ha‐1. Applications of ground mineral phosphate after spraying had no effect on sward output.

It is concluded that indigenous pasture plants in bracken‐infested areas of western Scotland cease growth by mid July unless subjected to major earlier defoliation or severe soil moisture deficits and the removal of the frond canopy does not change this pattern significantly. Obtaining the full benefit of bracken clearance depends on making use of the resulting production of extra herbage and limiting as far as possible frond regrowth in treated areas.
Photosynthesis, respiration and nitrogen fixation in white clover
Authors: HAYSTEAD A. , KING J. , LAMB W. I. C.
Published: April 2006

An apparatus in which shoot and root CO2 exchange and acetylene reduction can be simultaneously measured in specific white cloverrhizobium associations is described. In mature stolonating clover there was a fairly constant ratio between net photosynthesis, root respiration and acetylene reduction. Of the net carbon fixed daily (12 h light of 80 W m‐2, 400–700 nm; day/night temperature 15°C) 12% was lost during the dark period by the shoot and 17% by the nodulated root. Changes in the rate of acetylene reduction by nodulated root systems occurred more slowly than those in rates of root respiration in response to reduced irradiance. In 21·5 h continuous darkness the rate of acetylene reduction remained constant. Responses to increased irradiance were more immediate in both root respiration and acetylene reduction. In plants maintained at 15°C in a 12‐h, 80‐W m‐2 photoperiod there was no significant diurnal variation in acetylene reduction or root respiration. Acetylene depressed root respiration by 20%. Assuming the energy requirement of the nitrogenase system to be the same when reducing acetylene and N the depression can be used as an indication of the energy requirement of fixed N assimilation, metabolism and export in the nodulated root. Of the net carbon fixed daily 3·4% was utilized in this way in plants growing in a 12‐h photoperiod (80 W m‐2, 400–700 nm) at 15°C.
The relationship between the rate of fertilizer nitrogen applied to grassland and milk production; an analysis of recorded farm data
Authors: HAWKINS S. W. , ROSE P. H.
Published: April 2006

The milk yields obtained from 845 herd‐years within the ICI Recorded Farms Scheme have been correlated, by multiple regression analysis, with the N fertilizer supplied to the grassland, the quantities of concentrates fed and the stocking rates. The large quantity of data gave highly significant correlations which indicated that, over the whole period, the supply of an extra 1 kg N from fertilizer was associated with an average extra yield of 9·9 1 milk. 4·9 1 were associated with the extra N independently of any simultaneous changes in either stocking rate or concentrate feeding, and 4‐5 1 were ascribable to a simultaneous increase in stocking rate. There was a substantial variation in the ‘milk yield per kg N’ response from year to year, but the average value over 6 years agreed closely with that observed in the period 1949–52.
The effect of drying techniques on formononetin concentration in red clover
Authors: JONES R.
Published: April 2006

Oven‐drying at 60°, 80° or 105°C was compared with microwave and freeze‐drying as a method of preparing samples for the estimation of formononetin, the major oestrogenic factor in red clover. There was no significant difference in the formononetin concentration of clover samples either oven‐dried at 60°C or freeze‐dried. The formononetin concentration was reduced by drying at higher temperatures and by microwave‐drying but was not affected by wilting for up to 8 h after harvesting. The routine determination of formononetin in ten varieties of red clover showed no significant differences between samples cold stored at – 18°C prior to oven‐drying at 60°C and samples freeze‐dried.
Effects of rates and times of application of starter dressings of nitrogen fertilizer to surface sown perennial ryegrass‐white clover on hill peat
Authors: HAYSTEAD A. , MARRIOTT CAROL
Published: April 2006

The effects on clover and grass growth of five levels of ammonium nitrogen (NH4‐N) applied before sowing, at sowing and after nodule initiation have been investigated. A pot experiment in which S184 white clover was grown in a peat soil showed that NH4‐N up to 688 mg N per pot (approx. equivalent to a field rate of 120 kg ha‐1 N) applied before sowing and at sowing did not affect clover growth. N‐fixing activity (C2H2‐reduction), on the other hand, was reduced progressively up to the highest level (688 mg N per pot). Application after nodule initiation increased growth relative to the zero‐N treatment at all levels of application. Maximum growth and N fixation occurred at 516 mg N per pot where the DM yield was 70% higher than in the absence of added N. A field trial in which S184 clover and S24 perennial ryegrass were surface sown on to a peat soil showed an increase in grass and clover growth in the first year in response to 120 kg ha‐1 N applied at sowing. Grass growth alone was increased at 120 kg ha ‐1 N applied 40 d before sowing. Lower rates of application before sowing and at sowing did not affect clover or grass growth. The effect of the delayed application of NH4‐N on legume growth was less marked than that in the pot experiment, 90 kg ha‐1 N stimulating clover growth by 40% in the first year. The effect was however different from that in the pot experiment, in that, whilst 30kg ha‐1 N increased N fixation relative to the zero‐N treatment, plants exposed to higher levels showed a depression in N‐fixing capacity. N‐fixation was correlated with nodule numbers in the delayed NH4‐N application, the closest correlation being with the number of multilobed nodules which was highest at 30 kg ha‐1 N and lowest at 120 kg ha‐1 N.

It is suggested that circumstances exist when the use of a relatively low starter N dressing (20–60 kg ha‐1 N) at sowing would not increase clover or grass growth in the early stages of the establishment of a hill reseed. Under such circumstances higher rates of application (100 kg ha ‐1 N), preferably delayed until the seedlings are in a position to take up the nitrogen rapidly, would have the greatest effect.
The effect of daily herbage allowance and sward characteristics upon the ingestive behaviour and herbage intake of calves under strip‐grazing management
Authors: JAMIESON W. S. , HODGSON J.
Published: April 2006

Measurements of herbage intake and ingestive behaviour were made on British Friesian calves 4–9 months old, which were strip‐grazed on swards of S24 perennial ryegrass at three (Experiment A) or four (Experiment B) levels of daily herbage allowance in three (A) or four (B) 12‐d periods. Herbage intake declined by approx. 18% as daily herbage allowance was reduced from 90 to 30 g DM per kg LW in both experiments, but the relationship between intake and allowance was not consistent between periods.

Bite size and rate of biting were greater in calves on low than on high allowances after entry to a new strip of herbage but the positions were reversed towards the end of grazing. Reduced herbage intakes at low allowance resulted from reductions of approx. equal magnitude in bite size, rate of biting and grazing time, though not all of these effects were significant. It is suggested that these responses result from the increasing difficulty of prehending and ingesting herbage as swards are grazed down. The calves at low herbage allowances did not increase grazing time, probably because their behaviour was conditioned by anticipation of a new allowance of herbage.

Bite size and daily herbage intake were greater on a spring sward than on an autumn sward, but within experiments herbage intake was not consistently related to any of the sward characteristics measured.
Silage and milk production: comparisons between grass silage of three different chop lengths
Authors: CASTLE M. E. , RETTER W. C. , WATSON J. N.
Published: April 2006

Three grass silages of different chop lengths made from a uniform sward of S23 perennial ryegrass were compared in four experiments including a feeding experiment with twelve lactating cows, an eating behaviour study, a rate of passage investigation and a selection trial. The silages had median chop lengths of 9·4, 17·4 and 72·0 mm, termed short, medium and long, with pH values of 3·93, 3·94 and 4·17 and D‐values of 65·9, 65·2 and 64·4 respectively.

The daily intakes of silage DM and the daily milk yields increased as silage chop length decreased. The milk yield response to shorter chopping was significant with a supplement of groundnut but not significant with a supplement of sugar‐beet pulp. Chop length had small and generally non‐significant effects on milk composition.

Eating and ruminating times expressed as min per kg DM decreased as silage chop length decreased but the retention time of the silage residues in the entire digestive tract was not significantly affected by chop length. When offered simultaneously, the intakes of the individual silages were 52·2, 31·9 and 15·9% of the total DM intake for the short, medium and long treatments respectively.

Although silage with a chop length of 9 mm had nutritional advantages over longer silages, it is concluded that the mechanical and economic aspects of silage making must be considered fully when defining optimum chop length.
Concentrate supplementation, and the herbage intake and milk production of heifers grazing Cenchrus ciliaris
Authors: COMBELLAS J. , BAKER R. D. , HODGSON J.
Published: April 2006

Friesian heifers grazing Cenchrus ciliaris cv. Biloela were supplemented with 0, 3 or 6 kg concentrates daily during weeks 10–34 (±1·7) of lactation during either the rainy or the dry season. The overall responses to concentrate were identical between seasons at 0·27 kg extra milk and solids corrected milk per kg. Supplementation increased total feed intake and modified the grazing behaviour of cows. For each kg concentrate organic matter eaten, herbage organic matter intake was reduced by 0·64 and 0·42 kg in the rainy and dry seasons respectively and the time spent grazing by 11 min. Higher intakes in the dry season were the result of an increased rate of biting and were reflected in liveweight change but not milk yield.
Effect of time of spraying of glyphosate on the vegetation of an upland deep peat soil
Authors: WILLIAMS GARETH H.
Published: April 2006

The vegetation of an upland deep peat soil consisting mainly of Festuca rubra, Holcus mollis, Molinia caerulea, Juncus acutiflorus and Potentilla erecta was sprayed with 1·5 kg a.i. per ha glyphosate applied to separate plots at monthly intervals from April to August. In July of the following year, April and May applications showed no effect on sward composition while June, July and August treatments resulted in increasing proportions of mosses and bare ground. August spraying gave almost complete control of the indigenous species with the exception of F. rubra and mosses. The results are discussed in relation to the establishment of improved pastures in upland areas by surface seeding.
The effects of cereal supplementation of grass and maize silages
Authors: VADIVELOO J. , HOLMES W.
Published: April 2006

Grass and maize silages were fed alone and with two levels of a barley supplement to Friesian steers of about 300 kg liveweight. The organic matter (OM) intakes of grass and maize silage were similar although the OM digestibilities of the silages were 0·722 and 0·649 respectively. For both silages, barley supplementation increased total OM intake and total digestible OM intake by 0·46·0·08 and 0·37·0·06 g per g OM of supplement respectively. Liveweight gains on grass and maize silage diets were 1·38 and 1·20 kg d‐1 respectively, but the differences were not significant (P> 0·05).
Changes in dry matter yield associated with selection for canopy characters in ryegrass
Authors: RHODES I. , MEE S. S.
Published: April 2006

Studies have been carried out to measure the response to selection for canopy characters, as measured on young spaced plants, and the associated changes in sward yield in Lolium. In addition certain of the selection lines were compared with and found to be more productive than several existing bred varieties, indicating the considerable scope for improvement of dry matter yield through breeding.

The canopy characters which were associated with high yield are compared with those which confer high yielding ability on a spaced plant and an individual in a community. The plant breeding implications of the results are briefly discussed.
The response of Lotus uliginosus L. grown on hill soils to inoculation with Rhizobium
Authors: GWYNNE D. C. , BECKETT ROSEMARY E.
Published: April 2006

The response of marsh birdsfoot trefoil (Lotus uliginosus) to inoculation with appropriate Rhizobium spp. was compared over 2 years. Inoculated and uninoculated seed was sown at 5 kg ha‐1 on three soil types, brown earth, peaty podsol and deep peat. Perennial ryegrass cv. Perma was sown at 20 kg ha‐1 as a companion species. Plots received either no N or a light starter dressing of 30 kg ha‐1 N. Significant benefits from inoculation were recorded for Lotus germination and nodulation, Lotus and non‐Lotus herbage DM harvested and Lotus cover on the deep peat, and to a lesser extent on the other soil‐types. Due to particularly uneven early establishment, work on the peaty‐podsol site was discontinued at an early stage. There was a trend towards depression of Lotus where N had been applied to inoculated plots.
The effect of insecticide treatment on the establishment and growth of Italian ryegrass under different sowing conditions
Authors: HENDERSON I. F. , CLEMENTS R. O.
Published: April 2006

Italian ryegrass, Lolium multiflorum Lam., cv. RvP., was broadcast in spring on to fine and coarse seedbeds at seed rates of either 2 or 20 kg ha‐1. Each of the four combinations of sowing condition was either left untreated or treated with fungicide or insecticide. The establishment of the sown species and of weeds under each regime was measured and their relative contribution to dry matter assessed in four cuts during the sowing year. Seed rate affected weed invasion and yield more than seedbed condition. Insecticide treatment increased the establishment and yield of ryegrass and its contribution to total herbage yield under all four sowing conditions. The fungicide treatment had no effect. The improvements caused by insecticide treatment were associated with a reduction in the level of infestation by shoot flies, Oscinella spp. (Diptera: Chloropidae): the effect of a single treatment in April was still detectable in October.