bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of different cultivars of clover on numbers of and leaf damage by, some invertebrate species
Authors: MOWAT D. J. , SHAKEEL M. A.
Published: April 2006

Invertebrate numbers were studied in two white clover cultivars trials, grown with perennial ryegrass Weevils (Sitona spp.), slugs, lucerne flea, leatherjackets and as were more common (at least at some life stage) in cultivars of lower cyanogenic potential. Damage to clover foliage by the first three species was also negatively related to cyanogenesis. The production of HCN ranged from 0.025 mg to about 1.8 mg g−1 fresh leaf. There was no evidence of any other factor influencing cultivar preference.

Cyanogenesis had most effect on numbers of weevil larvae and leatherjackets. The effect on weevil larvae was attributed partly to intercultivar differences in oviposition, but it was also suspected that larvae had fed on cyanogenic parts of the plant before reaching the root. Leatherjacket numbers developed inter‐cultivar differences during larval growth. In one case these differences were detectable by December. By March in the second experiment there were approximately three times as many leatherjackets at the low as at the high end of the cyanogenic range. Approximately four times as many Sitona larvae were found at the lower as at the higher end of the scale. There was some evidence that a higher clover content in the sward was attractive to ovipositing Tipula paludosa but not in recently harvested cultivars of high cyanogenic potential
A comparison of the herbage productivity of Bromus wildenowii cv. Grasslands Matua with four cultivars of Lolium perenne when grown in association with Trifolium repens
Authors: HOPKINS A. , MURRAY P. J. , PATEFIELD W. M.
Published: April 2006

In a small‐plot trial five grass varieties bromegrass cv. Grasslands Matua, perennial ryegrass CVS. Melle (diploid) and Bastion, Condesa and Meltra (tetraploid) were established as grass/white clover swards with white clover cv. Menna. Productivity was measured under 6‐weekIy cutting both without N fertilizer (No) and with 100 kg N ha−1 applied in spring (N100) Evaluation was made over 2 harvest years, 1986–87.

Total mean annual production of herbage dry matter (DM) in the first harvest year at No and No was 5·07 t ha−1 and 6·93 t ha−1 respectively. In year 2, corresponding values were 11·81 and 12·67 t ha−1. In year 1, Matua swards at No and N100 yielded 5·08 and 6·65 t DM ha−1 compared with 507 and 70 t DM ha−1 for the mean of the four ryegrass varieties. In year 2, corresponding values were 12·90 and 12·29 for Matua and 11·54 and 12·78 for the four ryegrasses. In year 1, the digestable organic matter in the dry matter (DOMD) of the Matua swards was lower than that of Melle, Bastion and Condesa at NO, particularly at the first cut. In year 2, differences in DOMD between treatments and varieties were not significant.

The proportion of white clover was found to be higher in the No than the N100 treatment, and also higher in year 2 in most treatments. For the No treatment Matua swards had the highest proportion of white clover in year 1 (32% compared with 24% for the mean of the ryegrass varieties) but the lowest proportion in year 2 (27% compared with 60% for the ryegrasses). For the No treatment in year 1 clover production was also 43% higher, on average, from the tetraploid treatments than with Melle as the companion grass; for this comparison in year 2 the differences were not significant.

It is concluded that Matua bromegrass/white clover swards receiving no N fertilizer may have a good potential under cutting management. However, the evidence from this trial is that in the second year the proportion of white clover is lower with Matua swards than with perennial ryegrass as the companion grass.
Problems of estimating tissue turnover in grass swards in the presence of grazing animals
Authors: GRANT SHEILA A. , ELSTON D. A. , BARTHRAM G. T.
Published: April 2006

Rates of leaf extension and senescence were measured over three‐day intervals on neighbouring sets of caged and uncaged tillers on several occasions during summer 1983, both when grazing animals were present and also when they were absent. The weather was dry and drought conditions developed as the season advanced.

Comparison of data from caged and uncaged tillers indicated that some consistent differences occurred. Loss of information through grazing (affecting 30% of uncaged, larger than average, tillers), contributed to the significantly reduced estimates of leaf extension of ungrazed, uncaged tillers compared with caged tillers. Senescence rates were higher in the open plot than under the cages; old leaves were grazed on only 8% of uncaged tillers so that data loss was less important as a cause of bias. In the drought conditions prevailing, it was thought that caging in the presence of grazing animals resulted in reduced moisture stress and contributed to the above results.

Comparisons of caged and uncaged tillers when grazing animals were absent were made to examine the environmental effects of caging and the slight difference in tiller marking procedure. No differences were found in leaf extension rates, though a trend towards higher senescence rates for the uncaged populations was evident. It was concluded that the criteria limiting the use of cages (a period of protection less than the average interval between both leaf appearance and repeated defoliation) should be extended to include a time limit set by the need to avoid bias associated with the environmental effects of caging and cessation of grazing. To define this time limit better in particular circumstances, the extent and direction of bias in the estimation of leaf extension and senescence rates as affected by period of caging, tiller handling procedures, sward and climatic conditions requires further investigation.

In the case of vegetative tillers, estimates of leaf extension rates can be made considerably more precise by using tiller size variables (pseudostem length, total green leaf length, leaf width) as covariates. A suggestion for the number of tillers to be measured per transect is given. However, no such increase in precision can be made for estimates of senescence rates.
Modifying growth patterns in nine grasses with mefluidide
Authors: HAGGAR R. J. , ISAAC S. P. , STANDELL C. J.
Published: April 2006

Mefluidide was applied at 150ga.i.ha−1 on one of three dates (7, 28 March or 18 April, 1984) to irrigated field plots of nine grasses. Spraying suppressed flowering in the primary growth of most species, especially when carried out in mid‐ April. However, spraying at this time proved too damaging to amounts of herbage harvested. Spraying in March reduced mean yields by about one‐third at the first harvest and increased mean yields at the second harvest. In addition, spraying at this time increased herbage quality, as indicated by higher N and lower fibre contents, at least at the first harvest. In general, the grasses most responsive to mefluidide were tall‐growing and/or early‐flowering species, e.g. Arrhenatherum elatius, Festuca rubra, Dactylis glomerata and Holcus lanatus; by comparison, Lolium perenne was relatively less affected by spraying. The findings indicate the potential of mefluidide for overcoming the normal decline in herbage quality associated with flowering, and for transferring growth from spring to midsummer, albeit at some cost to total annual production.
Effect of seed crop management on the potential seed yield of contrasting white clover varieties.
Authors: MARSHALL A. H. , HOLLINGTON P. A. , HIDES D. H.
Published: April 2006

Three contrasting white clover varieties, Olwen (large‐leaved), Menna (medium‐leaved) and S184 (small‐leaved) were sown with and without a grass companion in 30 cm drills. Two grazing and one mechanical spring defoliation managements were imposed. Counts of the total number of inflorescences and of the percentage in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Inflorescence numbers were greatest in cv. S184 and least in cv. Olwen and, in general, varieties produced both more inflorescences and a greater proportion of ripe inflorescences when grown under spring defoliation managements similar to those for which they were bred. Thus, cv. Olwen produced more ripe inflorescences, and a lower proportion of brown inflorescences (semi‐ripe), after mechanical defoliation while cv. Menna produced more ripe inflorescences following mechanical defoliation and rotational grazing. However, cv. S184 produced more ripe inflorescences under both grazing managements than under mechanical defoliation. Optimum harvest date was not affected by management or variety, total inflorescence number and maximum ripe inflorescences having reached a peak on 11 September. However, varieties differed in the proportion of ripe and brown (semi‐ripe) inflorescences on this date, with cv. Menna and cv. S184 containing a significantly higher proportion of brown inflorescences than cv. Olwen, The implications of these differences in inflorescence development, the proportions of inflorescences in the various ripeness categories and their contribution to seed yield are discussed in relation to the management of white clover seed crops and harvesting method under UK climatic conditions.
Water‐soluble carbohydrates in perennial ryegrass breeding
Authors: HUMPHREYS M. O.
Published: April 2006

Water‐soluble carbohydrate (WSC) contents of the early heading perennial ryegrass cultivar Aurora and five late heading cultivars were assessed in samples from spaced plants cut five times in 1982. Aurora had the highest overall WSC content. Majestic and Aberystwyth S23 had the lowest while Perma, Melle and Ba 9795 were intermediate. Samples from F1 and F2 spaced plants derived from crosses between Aurora and the five late heading cultivars were also analysed for WSC contents and heading dates were recorded. As expected, heading date behaved as a polygenic character controlled mainly by additive gene effects. However, WSC contents behaved in a more complex way with evidence of non‐additive gene effects comprising dominance, overdominance (heterosis) and epistasis. It was concluded that by crossing contrasting cultivars, significant improvements in WSC content could be achieved, which may be more stable than those obtained by within‐cultivar selection.
The effect of frequency and height of defoliation on the production and persistence of ‘Grasslands Matua’ prairie grass
Authors: BELL C. C. , RITCHIE I. M.
Published: April 2006

The performance of prairie grass (Bromus willdenowii Kunth) cv. Grasslands Matua was examined under mowing at five defoliation intervals (10, 20, 30, 40 and 50 d) and two defoliation heights (3 cm and 8 cm). Annual and seasonal production of both the total herbage and of Matua, and the proportion of Matua in the sward, increased with less frequent defoliation. To a lesser extent, increasing the height of defoliation increased dry matter yield. Matua tiller numbers were increased by less frequent defoliation and were greater under the 8 cm than the 3 cm defoliation height. To increase prairie grass production and persistence, rest intervals between grazings of 40 to 50 d are recommended, or alternatively, a management involving silage or hay cutting offers scope.
The effect of dry feed additives on the nutritive value of silage
Authors: MOSELEY G. , RAMANATHAN V.
Published: April 2006

Silages were prepared in late September from a mixed crop of perennial ryegrass and white clover with low dry matter and high nitrogen content. Six different treatments were used during ensiling; addition of either molassed sugar beet pulp or rolled barley, at 50 kg and 25 kg (t fresh grass)−1, formic acid at 51 t−1 and no additive (control).

All silages were well fermented with low levels of ammonia and pH. The addition of rolled barley or sugar beet pulp increased the dry matter content of the silages incrementally and appeared to assist the retention of nitrogen in the silage.

Dry matter intakes of silages with 50 kg of barley or sugar beet pulp tonne−1 were similar to the control silage when fed to wether sheep but at 25 kg t−1, dry matter intake increased by 0·15 with barley and 0·04 with sugar beet pulp compared to the control. The digestibility of dry matter (DM) and organic matter (OM) were significantly higher than the control for silages treated with formic acid or high levels of barley and sugar beet pulp whereas neutral‐detergent fibre (NDF) digestibility did not appear to be significantly affected.

All treated silages had a significantly higher metabolizable energy (ME) content than the control, and additions of barley or sugar beet increased the ME content. The ME intakes of all treated silages were also significantly greater than those of the control, and the formic acid‐treated and low barley silages were the highest. This appeared to be associated with significantly higher energy digestibility and DM intake.

Addition of rolled barley during ensilage resulted in greater nitrogen intake, availability and retention compared to additions of sugar beet pulp. The higher retention with barley silages was associated with a significantly lower proportional loss of absorbed nitrogen in urine, which indicated a more efficient utilization of nitrogen.

These differences require further study to determine the mechanisms involved in the interactions between the energy source and herbage protein, both during fermentation and in the rumen.
A comparison of buffer and partial storage feeding of a straw/concentrate mixture to grazing dairy cows
Authors: ROBERTS D. J.
Published: April 2006

A straw/concentrate mixture was offered to set‐stocked dairy cows over a 24‐week period. The cows were offered grazed herbage only (G), or grazed herbage with a straw/concentrate supplement offered either for 45 min after each milking (B), or overnight (P). The overnight treatment involved housing the cows between afternoon and morning milking. The straw/concentrate mixture contained 0·33 long barley straw, 0·28 barley, 0·12 soya bean meal, 0·25 molaferm and 0·02 minerals. During the first 8 weeks of the experiment an average of 2·25 kg of concentrate were fed, and from weeks 9–24, 2·0 kg of concentrate were fed.

The feeding of the straw/concentrate mixture led to a decrease in estimated herbage dry matter (DM) intake, particularly for treatment P. Estimated total DM intakes were increased throughout the experiment by offering the straw/concentrate mixture. However, total metabolizable energy (ME) intakes were only increased in mid‐and late season.

Milk yield was higher in early season for treatment G; 28·1 kg d−1 compared to 26·8 kg d−1 and 25·5 kg d−1 for treatments B and P respectively. In late season the cows in treatment G had lower milk yields; 13·3 kg d−1 compared to 15·5 kg d−1 and 16·8 kg d−1 for treatments B and P respectively. Milk fat content was increased in early season in treatment P, and milk protein content tended to be reduced throughout the experiment for cows offered the straw/concentrate mixture overnight. Over the whole experiment there were no differences in yield of milk solids.
The effect of fertilizer sulphur on grass production for silage
Authors: KLESSA D. A. , FRAME J. , GOLIGHTLY R. D. , HARKESS R. D.
Published: April 2006

The effects of rate and pattern of fertilizer S application on herbage production from Perennial ryegrass‐dominant swards at six potentially S‐deficient sites in south‐west Scotland were measured under a silage cutting regime (3 cuts year‐1) with high fertilizer N application (300 kg ha−1 year‐1). Fertilizer S (as gypsum) was applied at annual rates from 0 to 48 kg ha−1 as single spring applications before the first cut or split before each of the three cuts. The residual effect of S in the year following its application was assessed at one site.

Applied S increased total DM production at four of the six sites. These increases were restricted to the second and/or third cuts and were generally in the range 10‐30% greater than where no S was applied. Timing of S application was not important in influencing annual DM yield. The residual effect of gypsum in the year following application was small.

The supply of available soil S is limiting herbage production in certain areas and soil types of south‐west Scotland. Areas of S deficiency are likely to increase in the future and need to be identified more precisely than they are at present.
Effect of changing grazing severity on the composition of perennial ryegrass/white clover swards stocked with beef cattle
Authors: GIBB M. J. , BAKER R. D.
Published: April 2006

During an experiment in which the height of mixed perennial ryegrass/while clover swards was maintained throughout the season at 3 or 7 cm (S and T, respectively), or were maintained al those heights until 30 June then changed (ST and TS), a limited study was made of the effects on the population densities and masses of the two species. During the earlier part of the season the short swards (S and ST) developed higher tiller and stolon growing point (sgp) densities, but with a reduced mass of ryegrass, principally of the pseudostem fraction, than the tail swards (T and TS). Thiere was little effect of sward height on the mass of clover. Whilst there was a general tendency for tiller and sgp densities to increase during the latter part of the season, tiller density increased greatly where sward height was reduced (TS) and both tiller and sgp densities were reduced where sward height was allowed to increase (ST). Changing sward height, whilst limiting the accumulation of dead grass material (TS), allowed grass leaf and dead masses to increase (ST), and adversely affected the increase in the clover component, principally of stolon material, in both ST and TS.
Application of a sequential sampling technique to DIY assessment of leatherjacket (Diptera: Tipulidae) populations in grassland
Authors: BLACKSHAW R. P.
Published: April 2006

The use of brine in plastic pipes inserted into the ground is now an established technique for sampling leatherjackets in grassland. Three sequential sampling plans were compared with a standard twelve‐pipe sample for the probability of a recommendation to spray and the number of sample units necessary before a decision over a range of population densities. Data derived from field studies showed a good fit with the expected outcomes. All four plan models were applied to leatherjacket distribution data from Northern Ireland, This shows the number of samples required before a decision was reduced with sequential sampling and that the use of single sequential samples would increase the risk of error. The results are discussed in the context of the physical limitations of the brine sampling procedure and it is concluded that a sequential scheme based upon groups of four pipes would reduce average sampling time by 36% without increasing error.
Effect of herbage water‐soluble carbohydrate content and weather conditions at ensilage on the fermentation of grass silages made on commercial farms
Authors: HAIGH P. M.
Published: April 2006

A total of 1009 samples of silage made in bunker silos on commercial farms between 1972 and 1978 was analysed to investigate the effect of herbage water‐soluble carbohydrate content (WSC) and weather conditions at ensilage on fermentation as measured by ammonia‐N concentration and pH of first‐cut grass silages.

Silage dry matter (DM) content had the major effect on fermentation. Factors influencing silage DM were rainfall and hours of sunshine during silage making, and DM content of the grass cut. WSC content of herbage ensiled also had a significant effect on subsequent fermentation. The major influences on herbage WSC were hours of sunshine and rainfall during the growing season.

The effect of chemical additives, albeit at poorly defined and often inadequate rates, was small in comparison to that of silage DM.

The minimum DM necessary to produce well‐fermented silage without additive was approximately 260 g kg−1. Use of formic acid significantly reduced this requirement to 240 g kg−1and to 252 g kg−1for sulphuric add + formalin. The results indicate that the minimum herbage WSC necessary to prevent a clostridial fermentation developing in silage with a DM content of 230 g kg−1is approximately 37 g kg−1without additive and 30 g kg−1with formic acid.

It is concluded that on commercial farms, weather conditions i.e. amount of rainfall and sunshine prior to and at ensilage, have a greater effect on subsequent silage fermentation than additive use.
Nutritive quality of little bluestem clones selected for phenotypic variability
Authors: KARN J. F. , TOBER D. A.
Published: April 2006

Little bluestem (Schizachyrium scoparium (Michaux) Nash), a perennial bunchgrass, is a potentially valuable species for use in restoring ground cover in shallow range sites that are subject to drought. However, there are no data on the nutritive quality of the diverse phenotypes of little bluestem found in the north central USA and south central Canada, and there are no cultivars of little bluestem that are adapted to these areas. The objectives of this study were to measure the nutritive quality of little bluestem clones sampled on different dates and to determine whether clones differed sufficiently to facilitate selection efforts to improve forage quality. Whole plant samples of little bluestem were clipped on 8 August and 8 September 1983 and 5 July and 6 August 1984 from a field nursery at Mandan, North Dakota, containing plants originating from Minnesota and North and South Dakota in the USA. Significant differences between sampling dates were found each year for in vitro digestible organic matter (IVDOM), crude protein, lignin, calcium, phosphorus (P) and potassium (K). In order to minimize the effects of maturity on chemical composition, data were statistically evaluated for clonal differences, using only the August sampling dates. Clones were further separated into north and southeast groups according to stage of maturity and latitude and moisture conditions where the clones originated. Clones were significantly different with respect to IVDOM and P in both the north and southeast groups for the August 1983–1984 data. IVDOM and P among clones averaged over years for the August sampling date ranged from 374to 521 g kg−1 and from O‐9to l‐6g kg−1, respectively, for the north group and from 456 to 538 g kg−1 and from 1–2 to 2–0 g kg−1, respectively, for the southeast group. The range in IVDOM and P suggests that selection to improve little bluestem quality components, especially later in the season, may be warranted. However, it is important that these results be corroborated under conditions where the effects of maturity are further diminished.
Comparison between isotope dilution and acetylene reduction methods to estimate N2 fixation rate of white clover in grass/clover swards
Authors: LAIDLAW A. S. , CHRISTIE P. , WITHERS J. A.
Published: April 2006

In two field experiments acetylene (C2H2) reduction by white clover in mixed swards was compared to N2‐fixed measured by 15N dilution. In both experiments, samples for C2H2 reduction were 7.5 cm diameter turves taken from plots within which microplots of 24 cm diameter were delimited and to which 15N was applied as ammonium sulphate (15NH4)2SO4). C2H2 reduction was assayed every 6–7 d. The rate of C2H2 reduction per unit length of stolon was applied to the estimated stolon length within the appropriate microplot at the time of assay, and the amount of C2H2 that would have been reduced within the microplot was estimated by integration.

In experiment 1, turves taken from grass/clover swards to which 0, 1·5, 3·0, 4·5 or 6·0 g N m−2 had been applied were incubated in sealed chambers (10% C2H2, 90% air). The mean ratio of C2H2 reduced to N2 fixed during 5 weeks was 0.74:1. Application of N fertilizer lowered the proportion of assimilated N derived from N2 fixation from 95% in unfertilized swards to 83% in those receiving 6 g N m−2 (60 kg N ha−1). In experiment 2, clover roots and stolons from plots that previously had been grazed were dissected from turves and incubated in a stream of C2H2 and air (i.e. the open system). The maximum rate of ethylene (C2H4) produced during the first 12 min was taken as a measure of true nitrogenase activity. The relationship between C2H2 reduced and N2 fixed was significant (r=0.80**). The mole ratio was 0.55:1 for the 6 weeks duration of the experiment, the low ratio possibly being due to disturbance of the nodules adversely affecting acetylene reduction. Mole ratios from both experiments were well short of the theoretical 4·3:1. Using the open system does not, therefore, overcome the shortcomings of the acetylene reduction technique for measuring N2 fixation of white clover in mixed swards.
Competition between white clover (Trifolium repens L.) and subterranean clover (Trifolium subterraneum L.) in binary mixtures in the field
Authors: HILL M. J. , GLEESON A. C.
Published: April 2006

White clover, (cv. Haifa) and subterranean clover (cv. Seaton Park) were grown in binary replacement series mixtures in the field at proportions of 100:0, 90:10, 50:50. 10:90 and 0:100, and cut every four weeks over three growing seasons from 1985 to 1987 at Scone, New South Wales (NSW) (32°S).

Relatively low plant densities minimized competition in 1985, but in subsequent seasons Haifa and Seaton Park competed vigorously for the same resource;.; usually having relative crowding coefficients greater than 1.0, and relative yield totals greater than 1.0 in spring of 1986 and 1987, and autumn 1987. This over‐yielding appeared to be due to some complementarity of leaf morphology and canopy architecture.

Haifa severely depressed seed production of Seaton Park in mixtures. Haifa regenerated as an annual in 1986, but as a perennial, from surviving stolons, in 1987 owing to lower maximum temperatures and better rainfall distribution in late summer and autumn of 1987.

It is concluded that white clover can survive severe competition from subterranean clover as a seedling, and if moisture allows, may severely depress seed production from subterranean clover, regardless of whether plants are annual or perennial in origin. Spatial separation may minimize competition in average years but competition effects may be severe in seasons with sufficient summer rainfall for perennation of white clover, and seasonal autumn rainfall for germination of subterranean clover.
The effects of grazing with and without excretal returns on the accumulation of nitrogen by ryegrass in a continuously grazed upland sward
Authors: THOMAS R. J. , LOGAN K. A. B. , IRONSIDE A. D. , BOLTON G. R.
Published: April 2006

Rates of N accumulation were studied on sheep grazed grass swards maintained at a constant height of 5 cm for two growing seasons (1985 and 1986) and receiving no N fertilizer using a tiller tissue turnover technique. Grazing with normal excretal returns resulted in an 85‐105% increase in the estimated rates of N accumulation by laminae compared with similarly grazed swards where excretal returns were prevented. Generally, increases in tiller numbers in plots receiving excreta were mainly responsible for the increased rates of N accumulation, rather than increased rates of N accumulation per tiller. Rates of N remobilization from laminae and senescence (flux of N to standing‐dead litter pool) per tiller, and rates of leaf extension and leaf appearance/disappearance were unaffected by excretal returns, in urine patches increased tiller numbers and increased rates of accumulation per tiller both resulted in greater estimates of N accumulation compared with tillers not visibly affected by excreta. However, at any one time only about 11% of the plot area was affected by excreta and increases in N accumulation in excreta patches could not account for the overall plot increases in rates of N accumulation.

The increased tillering in plots receiving excreta may have increased exploitation of the soil N. With an average stocking rate of 15 sheep ha−1, soil nitrate‐N, but not total N (Kjeldahl) nor bulk density, was increased during the winter of the second year as a result of excretal returns.
The effect of cutting systems on the yield of herbage from a small‐plot experiment
Authors: BINNIE R. C. , CHESTNUTT D. M. B.
Published: April 2006

Plots of an established perennial ryegrass sward (cv. Talbot) fertilized with 100 or 300 kg N ha−1 were harvested with one of three plot mowers; an Agria with 38‐mm finger spacing and an Allen Mayfield with 38‐mm finger spacing or 78‐mm finger spacing. The choice of mower was arranged factorially with four post‐harvest treatments: no post treatment; a second (cleaning) cut using the same mower and cutting in the same direction as the first (sampling) cut; a cleaning cut using the same mower, but in the opposite direction to the sampling cut; and a cleaning cut using a rotary mower. Sward productivity as organic matter (OM) was measured over four harvests at 6‐ to 7‐week intervals. The Agria mower resulted in 12·3 and 15‐9% more OM yield than the Allen Mayfield fitted either with knife‐bars at a similar spacing, or with wider‐spaced fingers, respectively. Yield of OM in the subsequent cut was reduced when a cleaning cut was taken; particularly when it was taken in the opposite direction to the sampling cut or when using a rotary mower.
An ultrasonic rangefinder for measuring the undisturbed surface height of continuously grazed grass swards
Authors: HUTCHINGS N. J. , PHILLIPS A. H. , DOBSON RUTH C.
Published: April 2006

An ultrasonic rangefinder (sonic sward stick) was developed for rapidly measuring and recording the undisturbed surface height of swards. HFRO and ultrasonic sward stick measurements of undisturbed sward height over continuously grazed pasture were closely related. The measurements obtained with both instruments were related to the sward mass; the distribution of that mass between leaf, stem and dead material had little effect.
Inorganic phosphorus and DNA concentrations in the leaf tissue of some forage species
Authors: HART A. L. , COLLIER W. A.
Published: April 2006

Ryegrass, some white clover cultivars (Grasslands Huia, Trifo, Barbian and Luclair) and lotus were grown in the presence of mineral nitrogen and at a range of phosphorus (P) supply. Ryegrass had the highest leaf inorganic P concentrations on a dry weight basis, and lotus the lowest. In the clovers and lotus shoot yield was correlated with inorganic P concentration; it was not correlated in ryegrass, although this was possibly a result of the stage of development of ryegrass when it was harvested. Ryegrass was always more efficient than the legumes in acquiring P and growing rapidly. When inorganic P concentration was expressed on the basis of DNA, lotus had concentrations intermediate between that of ryegrass and the clovers, i.e. lotus had at least as much inorganic P per unit of DNA as white clover. It is suggested that although lotus is more efficient than white clover in terms of the concentration of inorganic P on a dry weight basis, the amount of inorganic P required per ‘module of metabolism’ (or cell), is similar. Lotus also has larger cells than white clover and the relatively greater efficiency of lotus may lie at least partly in its ability to achieve an equivalent leaf area or weight with fewer cells, i.e. cytology contributes to efficiency.
Spatial analysis of forage parameters using geographic information system and image‐analysis techniques
Authors: SMITH S. M. , SCHREIER H. E. , BROWN S.
Published: April 2006

In efficient agricultural systems high production and high quality is expected throughout the year, but spatial and seasonal variation of biophysical variables can have a significant impact on the yield and quality of production. The yield and quality component of a forage field was monitored using statistical and Geographical Information System (GIS) techniques. The display of yield and forage quality in a spatial context proved to be very useful to the farmer since it allowed him to determine where in the field he obtained the best and worst production and whether such performance was consistent over the entire growing season. GIS is considered a new management tool that allows the spatial evaluation and presentation of production information in a new and innovative manner. Examples are provided to assist farmers in production accounting, to determine cause and effect relationships between management and production, to forecast production and to modify management to account for differences within the field.
Supplementary forage for grazing sheep. 1. Effects on lactating ewes and lambs
Authors: MARTIN J. H. , PHILLIPS C. J. C. , ALCOCK M. B.
Published: April 2006

In two experiments, ewes in weeks 1–20 of lactation received either pasture only or pasture plus ad libitum conserved forage. Herbage height was maintained at 3·3–3·4 cm on both treatments by manipulation of stocking rate in the 24 plots (twelve per treatment) used for the experiment with additional ewes and lambs. In experiment 1, silage, which was of lower metabolizable energy (ME) and crude protein (CP) contents than the grazed herbage, was consumed at an average of 375 g dry matter (DM) ewe−1 d−1. In experiment 2 a strawmix, containing (g kg −1 freshweight) 480 g barley straw, 300 g concentrate and 220 g molasses, again with a lower ME and CP content than the grazed herbage, was consumed at an average of 165 g DM ewe −1 d −1. In both experiments ewes not receiving forage lost weight whereas those with forage gained weight and tended to have increased body condition scores. Offering silage or strawmix did not affect lamb liveweight gain or stocking rate.
The effects of sodium chloride application to pasture, or its direct supplementation, on dairy cow production and grazing preference
Authors: CHIY C. P. , PHILLIPS C. J. C.
Published: April 2006

The experiment aimed to examine the effects of sodium chloride (NaCl) application to pasture on dairy cow production, distinguishing the effects of Na supply on pasture production from the direct effects on animal production, and also to examine the preference of dairy cows for sodium‐fertilized pasture. Twenty‐four dairy cows were grazed in six treatment areas with three fertilizer levels—all (A), one‐half (H) or none (N) of the area fertilized with 50 kg NaCl ha−1, and with or without 50 g cow−1 day−1 NaCl supplementation (+, −) offered in concentrate feed. The experiment was a changeover design with four 3‐week periods. NaCl fertilization increased herbage growth rate and Na, Cl and calcium (Ca) contents and reduced K content. Milk yield and liveweight gain were increased by NaCl application to pasture but not by direct supplementation. Milk fat content was increased with increasing Na concentration in the diet. Grazing time was increased by NaCl application to pasture, but only cows not receiving direct NaCl supplementation preferred NaCl‐fertilized pasture. Ruminating time was increased both by NaCl application to pasture and by direct supplementation. It is concluded that in the warm, dry conditions of this experiment, increasing Na supply to natrophilic herbage increased both pasture and animal production, and that within the range 3–8 g Na kg−1 dietary DM, increasing Na supply to the cow increased milk fat content.
The effect of adding surface water to herbage on its digestion by ruminants
Authors: PHILLIPS C. J. C. , MARGERISON J. K. , AZAZI S. , CHAMBERLAIN A. G. , OMED H.
Published: April 2006

In two experiments the effects of adding surface water to herbage on its digestion by ruminants were examined. In experiment 1, with sheep, adding water to silage reduced DM intake and the diet DM digestibility. Offering a high DM alternative forage, hay, increased DM digestibility with the wetted silage, but tended to decrease it with the dry silage. More hay was eaten with the wetted than dry silage. In experiment 2, with steers, adding water to fresh herbage reduced DM intake but had no effect on rumen pH or ammonia levels. Adding water to the herbage reduced the rate of DM disappearance from nylon bags placed in the rumen and the proportion of rumen liquor particles of low specific gravity. The proportion of very short and very long particles in the rumen liquor was also reduced by adding water to the herbage.
The effect of heat‐treatment and gamma radiation on the composition of unwilted and wilted lucerne silages
Authors: CHARMLEY E. , VEIRA D. M.
Published: April 2006

Three unwilted and three wilted silages were prepared from lucerne. Unwilted and wilted material was ensiled either without treatment (UWC and WC), after gamma irradiation (UWI and WI), or following heat‐treatment and inoculation with Lactobacillus plantarum (UWH and WH). Gamma radiation was from a cobalt 60 source. The UWH material was heat‐treated using steam, and WH material was treated with dry heat. At ensiling, irradiated material was considered to be sterile, and heat‐treated material had lost 80% of its original protease activity. Fifteen 1‐litre silos were prepared for each treatment (90 in total), and three from each treatment were opened after 1, 4, 14, 70 or 200 d ensiling. In irradiated silages, there was no accumulation of organic acids, but water soluble carbohydrate (WSC) concentration was almost double (116 g kg‐1dry matter) that at ensiling. This indicated extensive liberation of WSC from more complex carbohydrates during ensiling. The extent of silage fermentation in heated silages was similar to control silages. The WH silage had a higher proportion of the organic acids as lactic acid relative to the other treatments, possibly as a result of inoculation with L. plantarum. Proteolysis was unaffected by irradiation. However, heat‐treatment markedly reduced the extent of proteolysis, particularly in the first four days post‐ensiling. Deamination appeared to be related to the type of microbial fermentation rather than to the extent of proteolysis.
Interactions between pesticide treatment, cutting frequency and rate of N fertilizer on white clover grown in mixture with perennial ryegrass
Authors: LEWIS G. C.
Published: April 2006

The effects of a combined pesticide and fungicide (P + F) treatment on the proportion of white clover in an established perennial ryegrass/white clover sward were assessed on six occasions during 1988 and 1989, under two cutting frequencies (2‐ or 6‐week intervals) and with or without N fertilizer (120 kg ha‐1 per annum). In 1988 P + F treatment significantly increased the proportion of clover in August and October, with an increase at the latter harvest being much greater where N was also applied. There was no significant interaction between P + F treatment and cutting frequency, although less frequent cutting increased significantly the proportion of clover in October where N was not applied.

In 1989, drought prevented the proportion of clover from exceeding 1% throughout, regardless of management factors. P + F treatment significantly increased the proportion of clover in August, and significantly reduced populations of slugs, foliar‐feeding insects (mainly Collembola; Sminthuridae) and the area of clover leaf damaged by pests. No marked effect of P + F treatment on populations of plant parasitic nematodes was detected. No appreciable incidence of fungal diseases was observed in either year.
Herbage productivity of prairie grass, reed canary‐grass and phalaris
Authors: FRAME J. , MORRISON M. W.
Published: April 2006

The herbage production and quality of swards of three grass species, prairie grass (Bromus willdenowii Kunth), reed canary‐grass (Phalaris arundinacea L.) and phalaris (Phalaris tuberosa L.) were compared with perennial ryegrass (Lolium perenne L.) and hybrid ryegrass (L. perenne L. ×L. muitiflorum Lam.) under 6–cut (experiment 1) and 4–cut (experiment 2) regimes over 3 years at Ayr; annually, 360 kg ha‐1 fertilizer N were applied. At Edinburgh prairie grass was compared with Italian ryegrass (L. multiflorum Lam.), timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.) under an annual 4–cut regime for 3 years (experiment 3); fertilizer N application totalled 350 kg ha‐1 annually.

Prairie grass gave the highest annual dry matter (DM) production at Ayr, averaging 11·99 t ha‐1 in experiment 1 and 15·62 t ha‐1 in experiment 2. Reed canary‐grass was much less productive whilst phalaris did not persist after harvest year 1. On average, prairie grass gave 8–10% more DM than the three ryegrasses in the 6‐cut system but its advantage was much less under the 4‐cut regime. In experiment 3, the DM production of prairie grass and Italian ryegrass were similar in year 1, but following winter damage prairie grass gave the lowest production in subsequent harvest years.

Prairie grass had digestibility (OMD) values lower than the ryegrass but higher than reed canary‐grass, timothy and cocksfoot. The water soluble carbohydrate (WSC) concentrations in prairie grass were markedly higher than in timothy and cocksfoot but lower than those in Italian ryegrass. Prairie grass had relatively low P and Mg concentrations. Reed canary‐grass had relatively low OMD and Ca, but high N, P, K and Mg contents.

It is concluded that prairie grass may have potential in the UK as a special‐purpose species for conservation management but mainly in the milder climatic areas. The Phalaris species evaluated had disappointing agronomic potential.
Net production of herbage from a continuously stocked Lolium perenne‐dominated sward in late autumn
Authors: GUNN R. G. , SMITH W. F. , AGNEW R. D. M. , SMITH A. D. M. , SIM D. A.
Published: April 2006

Preliminary studies were carried out on the effect of stocking rate during late autumn on a continuously stocked Lolium perenne‐dominated sward at an upland site in central Scotland. Measurements were made of L. perenne tiller population density on 29 September and 2 November and of L. perenne net production, mean sward height and total herbage mass in early and late October and early and late November. Stocking rates were 12 ewes per ha during October and 8 and 16 ewes per ha during November. Sward height and herbage mass declined with time and more rapidly at the higher stocking rate. L. perenne growth per tiller and per unit area was influenced by time but not by stocking rate and was closely related to the 5·5°C soil temperature at 10 cm depth. Tiller senescence was greatly reduced at the higher stocking rate and/or the consequentially lower sward height and herbage mass. Tiller net production was therefore sustained at a positive level on the higher stocked sward throughout November while on the lower stocked sward it fell below zero early in November.
The reduction of frit fly oviposition on seedling ryegrass by the presence of oats
Authors: MOWAT D. J. , JESS S.
Published: April 2006

Seedling ryegrass and oat plants in various proportions were exposed to oviposition by frit fly in the laboratory. The growth stage of the ryegrass ranged from single‐leaved (unattractive as oviposition sites) to three‐leaved (almost immune to serious damage). Oat plants attracted most oviposition and their inclusion usually reduced oviposition on ryegrass, by up to 90%. Where the frit fly population density was so high that potential oviposition exceeded the availability of oviposition sites, inclusion of oats did not reduce the number of eggs laid on ryegrass.

This approach does not, therefore, show promise of a reliable control method against severe primary attack in the field, but is potentially useful over an important range of population densities at which further control measures might otherwise be required. The inclusion of oats would also provide an early warning of damage.
Growth performance, appetite and plasma ammonia concentrations in heifers fed inoculated lucerne prior to ensilage, then supplemented with sodium bicarbonate
Authors: PHILLIP L. E. , UNDERHILL L. , GARINO H.
Published: April 2006

A study was conducted to explore the possibility of a synergistic effect of an inoculum of lactic acid bacteria and sodium bicarbonate in improving the nutritive value of lucerne silage. Twenty Holstein heifers (live weight 183 ± 9·4 kg) were assigned to four dietary treatments consisting of: lucerne uninoculated or inoculated prior to ensilage and then either unsupplemented or supplemented with NaHCO3 (40 g kg−1 dry matter (DM)). The lucerne silage contained 320 g kg−1 DM and constituted 600 kg−1 diet DM. The animals were fed once daily for 90 d and samples of jugular blood were analysed for plasma ammonia and indices of blood acid‐base status. Inoculation of Lucerne reduced (P<0·01) silage pH but had no other effect on silage composition. In the absence of NaHCO3, liveweight gain and organic matter intake were improved by inoculating lucerne prior to ensilage; however, in the presence of NaHCO3, inoculation reduced growth rate but had no major effect on intake. Dietary treatment did not (P>0·05) affect the concentration of plasma ammonia or measures bf blood acid‐base status. The results suggest that NaHCO3 may have nullifled any potential benefit of inoculating lucerne silage to improve its nutritive value for heifers.
Decision rules for controlling the sward height of continuously grazed experimental pastures
Authors: HUTCHINGS N. J. , BOLTON G. R. , BARTHRAM G. T.
Published: April 2006

Two contrasting decision rules for adjusting stock density to control the sward height of continuously grazed grass swards were tested and developed. One rule calculated the adjustment as a percentage of the existing stock density (Percentage Rule); the other related the adjustment to estimates of the bulk density of the grazed horizon and individual animal intake (Absolute Rule). Both decision rules related the adjustments to the change in sward height over the previous week and to the deviation from the target value. The decision rules were tested by continuously grazing lactating ewes and then dry ewes after weaning with a target sward height of 4 cm on 0·33‐ha plots with stock density adjusted by varying animal numbers. The Percentage Rule failed to increase the stock density sufficiently rapidly when grass growth was accelerating, leading to increasing deviation in sward height from a 4 cm target value. The Absolute Rule succeeded in controlling sward height once the bulk density term had been correctly adjusted. Pre‐emptive adjustment of stock density in anticipation of a change in grass growth rate marginally improved the control that was achieved by the Absolute Rule.
Effects of sward height and bulk density on bite dimensions of cattle grazing homogeneous swards
Authors: LACA E. A. , UNGAR E. D. , SELIGMAN N. , DEMMENT M. W.
Published: April 2006

Effects of sward height and density on the dimensions and weights of bites taken by cattle were examined. In one experiment, swards of dallisgrass lamina were constructed by hand in a factorial combination of four heights (80, 150, 180 and 300 mm) and three densities (c. 700, 1500 and 2700 g m−3). In the other, swards of lucerne were constructed in a factorial combination of three heights (70, 150 and 250 mm) and three densities (1500, 2800 and 5900 g m−3). Treatments were replicated on three steers of 750 kg average weight. The first six bites taken from the sward were monitored, and functional relationships between sward characteristics and bite dimensions derived. Results from both experiments were similar. Average bite area was not constant as often assumed, but decreased linearly with density and increased quadratically with height, with slope negatively affected by density and height. In tail swards, bite area reached a plateau of c. 170 cm2, determined by the sweep of the tongue. In contrast with the widely used model, bite depth increased linearly with height, with slope negatively affected by density. Response of bite dimensions was explained by the mechanics of the interaction between tongue and jaw movements, and sward structure. Bite weight varied less than bite dimensions, because of compensatory effects between bite area, bite depth and density. Animals obtained heavier bites in tall sparse swards than on short dense ones of equal mass/area. Even in homogeneous swards, both density and height are necessary to predict bite weight.