bluuebunny/crossref_metadata_2025 huggingface dataset:
The voluntary intake and in vivo digestibility of herbage harvested from indigenous hill plant communities
Authors: ARMSTRONG R. H. , COMMON T. G. , SMITH HELEN K.
Published: April 2006

Voluntary intake and in vivo digestibility of herbage harvested from five indigenous communities–Agrostis‐Festuca, Nardus and Molinia grasslands and Eriophorum vaginatum‐ and Trichophorum caespitosum‐dominated varieties of blanket bog–and also from sown Lolium perenne and Trifolium repens swards were measured over two years. First growths of each sward were harvested at three stages of maturity and stored at — 20°C before feeding. Voluntary intake was measured while feeding ad libitum to 15% excess of the intake on the previous day and digestibility when feeding at 80% of voluntary intake.

There was a common positive relationship (r2= 0·86***) between intake (adjusted for year of feeding, range 72·8–16·7 g organic matter (kg LW)0·75 d‐1) and organic matter digestibility (range 0·796–0·371), covering Lolium perenne and most of the indigenous communities. However, there were significant differences between the regressions of intake on the concentration of neutral detergent fibre for ryegrass and the indigenous communities, and also between the regressions for individual communities.

The results demonstrated the general value of organic matter digestibility as a predictor of intake potential, and the high digestibility and intake potential of immature vegetation from the grass and grass heath communities.
Effects of pesticides and fertilizer on invertebrate populations of grass and wheat plots in Kent in relation to productivity and yield
Authors: LINZELL BRIGITTE S. , MADGE D. S.
Published: April 2006

At a site in Kent, perennial ryegrass (Lolium perenne) variety S24 and Italian ryegrass (L. multiflorum) variety RVP, wheat varieties Armada and Norman, and the original mixed grass ley were grown in small plots during 1982–84. Two toxic pesticides (phorate and aldicarb) were applied to half the total number of plots three times each year to eliminate soil invertebrate populations. Fertilizer was also applied to most plots. The yields of the crops, grown with and without pesticide, and the effects of the fertilizer were compared. Grass herbage yield was measured on three occasions during the summers of 1983 and 1984. Wheat grain yields were also determined in 1983.

During the first year significant differences were not apparent in grass dry matter yield between pesticide‐treated and non‐treated plots, but significant differences were found in the second year. The perennial ryegrass was more susceptible to pest damage than the Italian ryegrass or the grass ley. Grass yields varied between cuts and in relation to variety and pesticide treatment, yields tending to be greater in untreated plots. Fertilizer treatment greatly increased grass dry matter yields, particularly with the Italian ryegrass. The effects of pesticide treatment on both wheat varieties varied although some yield enhancement was evident.

Invertebrate animal populations in pesticide and fertilizer‐treated plots were also assessed in autumn 1982, spring and autumn 1983 and spring 1984. In contrast to pesticide treatment, fertilizer treatment had little effect on soil invertebrate populations. Nematode populations were reduced at each sampling occasion by the pesticide treatment. Slug populations were initially unaffected but were subsequently reduced. Leatherjackets, by far the most abundant pest in both grass and wheat plots, were markedly affected by pesticides on all sampling occasions. Generally, fewer soil‐dwelling dipterous larvae were recovered in spring than in autumn. Stem‐boring dipterous larvae were virtually absent.
Effect of three clover varieties on growth, 15N uptake and fixation by ryegrass/white clover mixtures at three sites in Wales
Authors: GOODMAN P. J. , COLLISON M.
Published: April 2006

Grass and clover production and nitrogen cycling were compared in 1983 and 1984 at three sites: an upland peaty gley and upland and lowland brown earths. The clover varieties Olwen and S184 were compared in 1983 and S100 and S184 in 1984. Ammonium and nitrate sources of 15N were used to measure nitrogen recovery from fertilizer and soil, nitrogen fixation and nitrogen transfer from clover to grass. Acetylene reduction was measured once, in 1983, but isotope dilution was used in both years.

Olwen clover produced more dry matter and took up more 15N than S184. Olwen fixed more nitrogen than S184 over the whole season, as measured by 15N isotope dilution. Companion grass took up more soil nitrogen when growing with S184 than with Olwen. The clover variety S100, tested at the lowland site in 1984, caused no significant variations in dry matter accumulation or N fixation.

In the dry 1984 season, grass dry matter accumulation and 15N uptake were less than in 1983, and plants actually lost total nitrogen from their roots to the soil. Fixation rate varied more in 1984 than in 1983. Nitrogen transfer from clover to grass was detected by isotope ratio differences in 1983, and by total N differences in 1984.

Site differences were dominated by the greater dry matter accumulation of Olwen in the lowland in 1983, but in that year there was also increased dry matter accumulation and increased 15N fertilizer uptake, but less nitrogen fixed on the mineral upland site than on the peat soil.

Whether 15N was given as ammonium or nitrate made little difference in these experiments.
Effect of fertilizers on the yield and chemical composition of pure sown white clover and on soil nutrient status
Authors: EVANS D. R. , THOMAS T. A. , WILLIAMS T. A. , DAVIES W. ELLIS
Published: April 2006

The effects of three levels of potash, phosphate and lime fertilizers on the yield and mineral content of white clover (Trifolium repens) and on soil nutrient levels were studied in a field experiment over 7 years. The aim of the experiment was to define an optimum fertilizer programme for breeding nurseries and experimental fields.

Potash was the main factor limiting production: clover yield was negligible after 2 years where no potassium was applied. Phosphate increased yields after the third year, while liming had no significant effect on clover yield.

The soil potassium status improved with the repeated application of potash over the 7–year period, but no consistent pattern was discernible for the phosphate treatments. There was a slight increase in soil pH with liming.

Application of phosphate increased the phosphorous content of herbage, but had no effect on other plant constituents for the first 2 years. Subsequent applications increased the calcium and sodium contents. Potash reduced the content of all constituents other than potassium as the treatment levels increased. Lime had little effect on plant constituents other than calcium.
Coefficients for the dry‐weight rank method of botanical analysis of pasture
Authors: SCOTT D.
Published: April 2006

The coefficients of the dry‐weight‐rank (DWR) method ('t Mannetje & Haydock, 1963) can be predicted from the general occurrence of the geometric series relationship between abundance and rank of species in a pasture using either an estimate of the percentage contribution of the first ranked species, or from the ratio of the contribution of two species.
Lime and major nutrient fertilizers required to establish a perennial ryegrass/white clover pasture on a non‐calcareous gley in the Scottish uplands
Authors: RANGELEY ANNE , BOLTON R.
Published: April 2006

A field experiment with mixed swards of perennial ryegrass and while clover carded out in 1982–83 using small cut plots is described. With perennial ryegrass, lime slightly decreased annual dry matter (DM) production in 1982 (the sowing year) but increased it in 1983 (the first harvest year) by about 1 t ha‐1. Applications of N and P produced small increases in DM in 1982 and greater increases in 1983. In the latter season annual DM production varied from an average of 3·5 to about 10 t ha‐1 with 0 or 480 kg N ha‐1 applied in three equal‐sized dressings throughout the growing season. Application of 40 kg P ha‐1 in 1982 increased DM production by about 2·5 t ha‐1 in 1983 but higher rates had little effect. Fifteen mg extractable P kg‐1 soil seemed sufficient to support levels of production normally expected from ryegrass pastures in upland Scotland, Applications of K did not affect DM production. N increased tiller weight and sward height of ryegrass; lime and P tended to increase tiller weight but this effect was not statistically significant. Leaf appearance and tiller number were not affected by treatments.

The white clover content of the pasture was decreased 10‐fold by application of N and increased by lime and P (1·45 and 1·46‐fold. respectively). The DM response to P was most apparent in limed soil and was also affected by the siting of the plots in the experimental area. Effects of lime and P on growth of white clover were to increase the number of stolon growing points and root nodule numbers per unit area.

The results emphasize the importance of lime and P fertilizer for establishment and growth of pasture in this soil and the differences between white clover and ryegrass in their responses to these.
Effect of stocking rate in early season on dairy cow performance and sward characteristics
Authors: BAKER ANNE‐MARIE C. , LEAVER J. D.
Published: April 2006

A comparison was made of stocking rates of 4·7, 5·6 and 6·4 cows ha‐1 during the first 7 weeks (period 1) of the grazing season. Each group of British Friesian cows was continuously stocked on a day and a night field. In the subsequent periods 2 and 3 (each lasting 7 weeks) the three groups were maintained at the same stocking rate within periods (4·2 and 31 cows ha‐1, respectively). The differential stocking rates were achieved by the addition and removal of cows.

The stocking rates applied in period I had no significant effects on milk yield, milk composition, liveweight change or condition score, in any period. Milk production ha‐1 over the three periods totalled 12390,13 978 and 14986 kg, and the estimated utilized metabolizable energy totalled 773, 81·5 and 86·6 GJ ha‐1 for low, medium and high stocking rates, respectively.

Increased stocking rate in period I was associated with a decrease in sward height in periods 1 and 2. This led to an increase in herbage metabolizable energy, and crude protein contents, and to an increase in tiller population density. The lowest stocking rate gave greater live individual tiller weights throughout the experiment and a longer interval between defoliation of individual tillers in period 1.

The results indicate that high stocking rates in the spring are not necessarily detrimental to overall summer performance of spring calving dairy cows. However, high stocking rates in the early season ensure a high level of herbage utilization and milk output ha‐1 in that period. Although this practice leads to a reduced sward height in mid season, the sward has less rejected area, a higher tiller population density and a higher digestibility than swards stocked at a lower level.
Growth of white clover in eight grass species and the effects of propyzamide, a grass‐suppressing herbicide
Authors: WILLIAMS E. D. , HAYES M. J.
Published: April 2006

Seedlings of white clover (cv. Grasslands Huia) were introduced as spaced plants into 3‐year‐old monoculture plots of eight grass species (Agrostis capillaris, Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus, Lolium perenne, Phleum pratense and Poa pratensis) during June 1984. In mid‐April 1985 plots were split for application of propyzamide at the following concentrations: 0, 0·2, 0·4, 0·6 kg a.i. ha‐1.

During 1984 differences between clover seedling growth in the different grass species became apparent within 2 weeks; growth was greatest in F. rubra, P. pratensis and H. lanatus and smallest in D. glomerata, L. perenne and P. pratense. During 1985, when more N fertilizer was given, H. lanatus and D. glomerata, were equally competitive and clover contributed only 16–18% of the total herbage yield of 10·4 t ha‐1 in them, compared with 33–50% of yields ranging from 9·6 to 119 t ha‐1 in the other six species. Propyzamide decreased grass growth in mid‐season by more than 50% but there was little overall persistent benefit to clover yield, except for A. stolonifera and P. pratense with 0·4 and 0·6 kg ha‐1 treatments. Dactylis glomerata and perenne were least and H. lanatus, F. rubra and P. pratensis most suppressed by the herbicide.

Possible reasons for the overall large clover contribution from a very sparse seedling population and the relatively small effects of propyzamide are discussed as well as future work required to improve the predictability of effects of grass suppression.
The influence of forage quality and concentrate level on dry matter intake and milk production of British Friesian heifers
Authors: PHIPPS R. H. , WELLER R. F. , BINES J. A.
Published: April 2006

Thirty‐six British Friesian heifers were divided into two groups during weeks 3‐26 of lactation and received ad libitum either good (G) or average (A) quality grass silage. The in vitro digestible organic matter in the DM was 680 and 600 g kg‐1 for silages G and A, respectively. In addition, the heifers in each group were offered concentrate at either a low (4.3 kg DM d‐1), medium (64 kg DM d‐1) or high (8.4 kg DM d‐1) level. The concentrate contained 180 g (kg DM)‐1 of crude protein and had a calculated metabolizable energy concentration of 12.9 MJ (kg DM)‐1.

Increasing concentrate level significantly increased milk yield (P < 0.01), milk protein concentration (P < 0.05), and yield of both milk protein depressed milk fat concentration (P < 0.001) and silage intake (P < 0.001).

Although the overall effect of silage quality on milk yield was not significant, the milk yields for silage G at each concentrate level were higher, significantly so for low level, than the corresponding values for silage A. An improvement in silage quality did not affect milk fat concentration but significantly increased the concentration of milk protein (P < 005) and yields of both milk fat (P < 005) and protein (P < 0001). The response of silage DM intake to improved silage quality was 0 06 kg DM per 10 g rise in vitro DOMD value. Each additional kg concentrate DM depressed intake of silages G and A by 0‐63 and 0‐27 kg DM, respectively. Substitution rate was also significantly related to stage of lactation.

With both silages, the digestibility coefficients determined in vivo for acid detergent fibre (ADF) decreased significantly (P < 0.001) when concentrate level was increased from low to high. Differences for DM, OM and total N digestibility coefficients between treatments were not established as significant at the 5% level.

Estimates of mean efficiency of utilization of ME for lactation, made on a weekly basis, were 049 and 052 for the heifers given silages G and A. respectively, and 048, 052 and 052 for those given the low, medium and high levels of concentrate. Energy balances were calculated on a mean weekly basis.
The effect of cutting and grazing managements on dry matter yield of white clover varieties (Trifolium repens) when grown with S23 perennial ryegrass
Authors: EVANS D. R. , WILLIAMS T. A.
Published: April 2006

The effects of three defoliation treatments upon the performance of eight white clover varieties when grown with S23 perennial ryegrass were investigated. These treatments included a cutting only regime as used in National List trials and rotational and continuous sheep grazing.

There were significant (P<0·001) differences between treatments, and the ranking of clover varieties also differed between the three treatments. The significance of this finding is discussed in relation to the evaluation of breeding material and varieties prior to recommendation to farmers.

Clover yields were less under grazing than cutting. This was due mainly to the selective grazing and removal of stolon material which occurred in the former treatments. Differences in the grass/clover balance resulting from the three treatments are discussed in relation to the degree of protection afforded to the clover stolons by the grass component.
Silage intake and milk production in cows given barley supplements of reduced ruminal degradability
Authors: KASSEM M. M. , THOMAS P. C. , CHAMBERLAIN D. G. , ROBERTSON S.
Published: April 2006

Three change‐over experiments were conducted to determine the effect on ad libitum silage intake and milk production in dairy cows of treatment of barley supplements with an acid‐formaldehyde reagent designed to reduce the rate of starch and protein digestion in the rumen. In Experiment 1 there were six dietary treatments consisting of silage with supplements of 4·0,6·5 and 9·0 kg d‐1 of barley given untreated or treated with formaldehyde reagent (8·1 t‐1). In Experiment 2 there were four dietary treatments consisting of silage with supplements of barley (7·0 kg d‐1) or barley and fishmeal (6·0 kg d‐1 plus 1·0 kg d‐1), with the barley untreated or treated with formaldehyde reagent (15·1t‐1). In Experiment 3 there were four dietary treatments consisting of silage given alone or with supplements of barley (9·0 kg d‐1). Treated barley (15·1 t‐1, 9·0 kg d‐1) and barley plus sodium bicarbonate (9·0 kg d‐1 plus 25·0 g d‐1).

Treatment of the barley supplement with formaldehyde reagent had no effect on silage intake or milk production in Experiment 1 where the rate of application of the reagent was low and the basal silage‐barley diet was limiting in rumendegradable nitrogen. However, in Experiments 2 and 3 treated barley supplements were associated with improvements in silage intake and milk production. As compared with corresponding control diets containing untreated barley, increases in silage intake ranged from 0 to 0·16 of the control value, whilst associated increases in the yields of milk, milk fat, milk protein and lactose were 0·077–0·089, 0·016–0·026, 0·092–0·118 and 0·080–0·092 of the control value. These responses are discussed in relation to the increases in silage intake and milk production observed with fishmeal supplementation of the diet in Experiment 2 and inclusion of sodium bicarbonate in Experiment 3.
The effect of herbage surface water and the provision of supplementary forage on the intake and feeding behaviour of cattle
Authors: BUTRIS G.Y. , PHILLIPS C.J.C.
Published: April 2006

High rainfall and the corresponding low herbage DM content has been shown to adversely affect cattle intakes and production. This could arise from physical restrictions on intake or digestion rate, or other behavioural limitations such as reduced palatability. A knowledge of the reason for the intake reduction would assist in determining the optimum supplement to feed. Eight steers were offered four diets in a changeover design. The diets were: A, cut herbage; B, cut herbage with added surface water; C, as B but with a low dry matter (DM) forage supplement (silage); and D, as B but with a high DM forage supplement (hay). The addition of surface water to herbage reduced DM intake and feeding time but had no effect on biting rate or rate of intake. Neither hay nor silage was eaten in sufficient quantities to restore DM intake, even though the silage was of similar nutrient composition to the herbage.
The effect of nitrogen in spring on shoot number and leaf area of white clover in mixtures
Authors: DENNIS W. D. , WOLEDGE JANE
Published: April 2006

Swards of perennial ryegrass/white clover were cut to 3 cm in March and allowed to regrow for approximately thirteen weeks. Half the swards received nitrogenous fertilizer at the time of cutting (+N treatment) while the other half received none (—N treatment).

About four weeks after the application of treatments, the number of clover shoots in the — N treatment was significantly higher than that in the +N; at this stage total leaf area index on both treatments was low, but significantly greater in the + N. After 30 days, more light was reaching ground level in the — N treatments, and about 40 days after cutting there was between 17 and 50% more clover in the — N treatment than the +N.

It is suggested that the inhibition of stolon branching with a consequent restriction in the rate of increase of clover leaf area is a major factor in the adverse effect of N fertilizer on clover.
The effect of strategic nitrogen application and defoliation systems on the productivity of a perennial ryegrass/white clover sward
Authors: FRAME J. , PATERSON D. J.
Published: April 2006

The productivity of a mixed sward comprising perennial ryegrass cv. Fantoom and white clover cv. Aran was measured under eight defoliation management systems and two fertilizer N rates (0 and 75 kg ha‐1) applied in spring. The defoliations involved a basic six‐harvest simulated grazing system together with the interposition of silage cuts once or twice at varying times during the growing season; evaluation was made over three harvest years, 1983‐85.

Mean annual production of total herbage DM over the three years was 8.351 tha‐1 without N and 9.49 tha‐1 with 75 kg N ha‐1, a mean response of 15.2 kg DM per kg applied N. The responses for individual treatments occurred mainly at the first cuts, whether for simulated grazing (a mean of 12 9 kg DM) or for silage (a mean of 259 kg DM); however, this influence of spring N was not sustained at other cuts over the season. Mean annual white clover DM production was 4.19 t ha‐1 with no N and 3.32 t ha‐1 with 75 kg ha‐1 N, but the reduction due to N was not significant in any year. The mean amount of clover stolon DM present post harvest over all management systems was 1.33 t ha‐1 with no N and 1.03 t ha‐1 with 75 kg ha‐1 N.

Mean annual DM production of total herbage from the six‐harvest system was 8.11 t ha‐1 Compared with 8 88 t ha‐1 (a 9% increase) from the systems with one silage cut and 9.241 ha‐1 (a 14% increase) from the systems with two silage cuts. Corresponding white clover DM production was 4.02, 3 87 and 3 53 t ha‐1, respectively, and mean stolon DM amounts post harvest, 1 12,1.15 and 1‐23 t ha‐1, respectively.

It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. Spring N application did not greatly reduce white clover production in this experiment where white clover was at higher levels than are likely in farming practice and the swards were not grazed. More knowledge of spring N rates, and indeed of N application rates generally, would be advantageous in future assessment of silage cutting systems.
Redistribution of nitrogen and phosphorus on Palace Leas meadow hay plots as a result of aftermath grazing
Authors: SHIEL R. S. , BATTEN J. C.
Published: April 2006

Aftermath grass growth on Palace Leas meadow hay plots at Cockle Park Experimental Farm, Northumberland, is well correlated with hay yield, but there is variation in grazing intensity and dunging pattern between plots leading to a redistribution of nutrients. Plots which are low in nutrients, as a result of treatments applied since 1897, receive inputs from the surrounding plots but these have not prevented the development of large differences in flora, hay yield and soil properties between plots. Variation in grazing intensity between plots may have contributed to an increase in soil organic matter content on some of the more acid plots.
Productivity and persistence of prairie grass (Bromus willdenowii Kunth)
Authors: FALLOON R. E. , HUME D. E.
Published: April 2006

A field trial measured effects of the head smut fungus Ustilago bullata Berk, on forage productivity of prairie grass (Bromus willdenowii Kunth). Simulated swards containing different proportions of U. bullata infected and non infected plants were established in the autumn, and sward and plant parameters were measured over the following 15 months. Total herbage produced from swards containing only non‐infected plants was 27.3 t ha−1, while that from totally infected swards was 14.6 t ha−1. Infected plants produced fewer and lighter tillers than non‐infected plants when both were growing together in swards. Almost all the U. bullata infected plants died during an epidemic of bacterial wilt disease (caused by Xanthomonas campestris pv. graminis (Egli, Goto and Schmidt) Dye), while most of the‘non‐infected plants survived. The deleterious effects of U. bullata on individual plant productivity affected sward productivity only when the proportion of infected plants in swards was greater than 50%. Plants not infected with U. bullata compensated for low productivity and death of infected plants by producing large numbers of tillers.
Water use and water‐use efficiency of perennial ryegrass swards as affected by the height and frequency of cutting and seed rate
Authors: COX RUTH , PARR T. W. , PLANT R. A.
Published: April 2006

The effects of cutting height (20 and 44 mm), frequency (once every 2 weeks April‐September inclusive and twice a year) and seed rate (250 and 20 kg ha‐1) on the water use and herbage yield of perennial ryegrass swards, for 3 years after sowing, were compared.

Frequent cutting and a low cutting height reduced water use in the first year only. In later years infrequent cutting led to higher yields and higher water‐use efficiencies, but did not affect total water use or the shape of the soil water profile. Seed rate influenced sward composition and the pattern of water use, but not total water use. The swards from the low seed rate had a lower stubble biomass and tiller density, and extracted relatively more water at depths of 75 and 85 cm and less at depths of 15 and 35 cm, than the swards derived from the high seed rate.

The ratio of actual: potential evapotranspiration was reduced as the soil water deficit increased and was lowest in the summer after a dry spring. Cutting height and frequency during summer were shown not to be effective methods of either conserving water or manipulating the effective rooting depth of an established sward.
A comparison of nitrogen fertilizers for spring and summer grass production
Authors: SWIFT G. , CLELAND A. T. , FRANKLIN M. F.
Published: April 2006

Three experiments were carried out in 1983‐85 to compare split dressings of ammonium nitrate and urea with a single injection of aqueous ammonia for seasonal and total annual dry matter (DM) production. Total annual fertilizer nitrogen (N) applied was 360 kg ha1 for a six‐cut management. The solid fertilizers were applied in spring at different dates for the first cut and then after cuts 1 —4in the pattern 90,90,60,60,60 kg N ha1. A winter injection of aqueous ammonia in the first year was replaced thereafter by early and late spring injections, the latter at 300 kg N ha1 with 60 kg N ha 1 as ammonium nitrate. Injection was to a depth of 100 mm at 30 cm spacing using a commercial applicator. The experiments were carried out on farms in a low rainfall area; the soils were sandy loams.

Urea gave 3% less total DM production than ammonium nitrate (0middot;32±0middot;153 t ha‐1) and produced on average 7% less DM in the spring, and 12% less in dry conditions in early autumn of 1984. Lower production was associated with reduced uptake of N, which occurred at most cuts. From these experiments it is concluded that urea can be a suitable alternative to ammonium nitrate, and when used in spring must be about 20% cheaper per kg N. The performance of aqueous ammonia was variable. In the dry summer of 1984, when applied in early April with 60 kg N ha‐1 as ammonium nitrate it equalled the ammonium nitrate treatment in both spring and total production and was better (P< 0 −05) in early autumn. In the same year, an early March injection was inferior (P < 0 05) in total DM production to ammonium nitrate. This early injection was also lower, but not significantly (P>005) in 1985, mainly because of lower spring production. A delayed, mid‐April injection, plus ammonium nitrate, in 1985, gave even less spring growth and lower total production. A January injection, in 1983, showed poor persistency and is not recommended for sandy loam soils.
Particle size reduction of the leaves of a tropical and a temperate grass by cattle
Authors: WILSON J. R. , AKIN D. E. , McLEOD M. N. , MINSON D. J.
Published: April 2006

To investigate links between the anatomy of grass leaves and their resistance to breakdown in the rumen, leaf blades of the tropical grass, green panic (Panicum maximum var, trichoglume), and the temperate grass, Italian ryegrass (Lolium multiflorum), were chopped into 50 mm lengths and fed fresh to cattle. Particle size reduction of the chewed feed was studied immediately after eating and after digestion in nylon bags in the rumen for 6, 12, 24, 48, 96 h and 3 weeks. The lengths of fibre elements, separated into groups of different diameters, were measured on samples digested for 96 h. The process of tissue breakdown was studied using light and electron microscopy.

Green panic leaves had twice the cross‐sectional area of thick‐walled tissues, a higher vascular bundle frequency per unit leaf width, and less, but more densely packed mesophyll, than did the ryegrass leaves. Despite the contribution of these characteristics to greater leaf rigidity, green panic was broken down to a greater degree by chewing than was ryegrass.

During digestion, width reduction of the chewed leaf particles was faster in ryegrass than in green panic because of two anatomical features: (i) the straight‐walled intercostal cells of the epidermis in ryegrass were easily separated allowing the epidermis to split, whereas the sinuous walls in green panic were resistant to splitting, and (ii) the epidermis of ryegrass was linked to the vascular bundles by thin‐walled mesophyll cells and was shed when these were digested, whereas in green panic the linkage was via thick‐walled bundle sheath cells causing the epidermis to remain attached for much longer. Ryegrass leaf was reduced to isolated fibres within 24 h digestion; this process took >48 h in green panic. These fibres all had a high resistance to length reduction by digestion irrespective of their anatomical or species origin. Even after 3 weeks in the rumen there was little digestive disruption to the longitudinal walls of these fibres.

The isolated vascular fibres of ryegrass were smooth‐surfaced in contrast to those of green panic which were rough owing to attached undigested bundle sheath cells and jagged, broken sections of epidermis; this could influence ease of separation of particles from the digesta mass and flow from the rumen.

Anatomical differences between these grasses were, therefore, important in the rate of width reduction of leaf particles during digestion and for the characteristics of the isolated fibre, but not for length reduction of particles during digestion
Chemical Composition, in vitro digestibility and in vitro VTA concentrations of New Mexico native forages
Authors: HOLECHEK J. L. , ESTELL R. E. , GALYEAN M. L. , RICHARDS W.
Published: April 2006

Comparative chemical composition, in vitro digestibility, and in vitro volatile fatty acid (VFA) concentration and molar proportions of current year's growth of twelve important native New Mexico forage species were evaluated. Volatile fatty acid data were collected on forage samples subjected to 12‐h in vitro digestion using two different inoculum sources. Forbs and shrubs had higher (P<0·05) total nitrogen and total available‐ nitrogen concentrations than grasses; however available nitrogen as a percentage of total nitrogen did not differ (P>0·05) among grasses forbs and shrubs. in vitro organic matter digestibility (IVOMD) was higher (PKOOS) for forbs and shrubs than grasses for all incubation periods (24, 48, 72 hours). Lucerne hay and prairie grass hay inocula gave similar IVOMD results. Based on 24‐h IVOMD divided by 72‐h IVOMD, forbs were digested more rapidly than grasses (P<0·05). Total VFA concentration and molar proportion differences among grasses, forbs and shrubs were small
Yield of white clover populations in mixture with contrasting perennial ryegrasses
Authors: COLLINS ROSEMARY P. , RHODES IAN
Published: April 2006

A field experiment was established in May 1986 in which four white‐clover populations originating in Switzerland, and a bred variety, Menna, were grown in binary mixtures with their ‘co‐existing’ perennial ryegrasses and three other bred ryegrasses— Aurora, Talbot and Melle. The productivity of both components of the mixtures was measured by cutting samples in October 1986 (after establishment) and on five occasions during the growing season in 1987, Substantial differences were observed between clover yields in different mixtures, and the yield ranking of clover was found to vary with companion grass. It was concluded that the interaction between grass and clover populations originated at an early stage in sward development, being evident in both the 1986 establishment cut and the spring cut of the following year. The implications of these results for the formulation of breeding objectives and the evaluation of breeding material are briefly discussed.
The effect of some invertebrate species on persistence of white clover in ryegrass swards
Authors: MOWAT D. J. , SHAKEEL M. A.
Published: April 2006

In two experiments in established swards of perennial ryegrass and white clover, plots were treated with pesticides to control slugs, leather‐jackets, weevil larvae and lucerne flea as selectively as possible. Other plots were treated to control ail of these pests.

Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather‐jackets. Other effects on non‐target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.

At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3‐year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha−1 in the final year. At the other site, where the clover content was low (ultimately 01.1–6%), leather‐jacket populations reached 2.1 m ha−1 and slug numbers were also relatively high. Control of these species contributed most to the relative increase in clover content and yield.
Nitrogen in the detergent fibre fractions of temperate legumes and grasses†
Authors: SANDERSON M. A. , WEDIN W. F.
Published: April 2006

Data are few on concentrations of nitrogen (N) in the cell wall and lignocellulose (neutral‐ and acid‐detergent fibre (NDF and ADF), respectively) of herbage. Herbage N can be partitioned into neutral‐ and acid‐detergent soluble and insoluble N to crudely estimate rapidly degradable (N soluble in neutral detergent), slowly degradable (neutral‐detergent fibre N (NDFN) minus acid‐detergent fibre N (ADFN), herein termed available fibre N (AFN)), and indigestible N (ADFN) in the rumen. Our objective was to examine the effects of herbage species, maturity stage, and plant part on N in the NDF and ADF of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and smooth bromegrass (Bromus inermis Leyss.). Herbage was harvested at four 2‐week intervals during spring of 1984 and 1985. Leaves, stems and total herbage were analysed for total N, and N in NDF and ADF. Concentrations of N in ADF in leaves, stems, and total herbage of lucerne and clover were twice that of grass ADF. This may be due to greater lignin concentrations generally reported in legumes. Concentrations of NDFN in leaves of lucerne, clover, timothy, and bromegrass were 9–8, 26.4, 8.6, and 6.4 g kg−1 of NDF, respectively, averaged over harvests and years, whereas stem concentrations were 4.2, 4.6, 32, and 2.4 g kg−1 of NDF, respectively. Leaf concentrations of ADFN in lucerne, clover, timothy, and bromegrass were 4.6, 5.3, 20, and 1.6 g kg−1 of ADF, respectively, averaged over harvests and years, whereas stem concentrations were 3.4, 33, 14, and 14 g kg‐’of ADF, respectively. As a proportion of the total N, NDFN and ADFN increased with plant maturity in leaves, stems, and herbage. In stems, 49% of NDFN was ADFN, whereas in leaves only 21% of the NDFN was ADFN. The larger portion of ADFN in stems probably reflects the larger proportion of lignified xylem and other structural tissues, which have a greater proportion of lignified secondary cell walls, whereas the greater proportion of NDFN in leaves may mirror the greater amount of mesophyll cells with primary cell walls. More than 80% of the total N in leaves, stems, and herbage was in the cell solubles, which may be rapidly ruminally degradable.
A correction for the influence of changes in lamina weight per unit length in grasses on measurements of the weight of lamina removed by grazing
Authors: Tallowin J. R. B. , TCACENCO F. , PATEFIELD M. , BROOKMAN S. K. E.
Published: April 2006

Changes in the weight per unit length along the first and second fully‐expanded laminae of Lolium perenne, Agrostis stolonifera, Holcus lanatus and Poa trivialis were experienced in tillers harvested in April and June 1987 from a permanent pasture under contrasting nitrogen treatments. Schematic models representing the weight distribution along the laminae of the different species are presented. From these models, predictions of the weight of any given proportion of the lamina length have been calculated. The weight of segments of lamina have been estimated, using the appropriate lamina model for a species, and these estimates provided consistently greater precision than estimates of lamina weight when no correction for lamina shape was considered, the length of a segment of lamina simply being multiplied by the mean overall weight per unit length of the lamina.
A further study on the evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage
Authors: GORDON F. J.
Published: April 2006

An experiment is described in which three silages were prepared from herbage treated with either a bacterial inoculant (Ecosyl, Imperial Chemical Industries plc) at 2‐71 t−1, formic acid (850 g kg−1, Add‐F, BP Chemicals International Ltd.) at 2‐21 t−1, or no additive (control). The herbage (second regrowth from perennial ryegrass swards), was ensiled unwilted, and had mean dry matter (DM) and water‐soluble carbohydrate concentrations at ensiling of 186 and 34‐1 g kg−1 respectively. The resulting silages were all well preserved and had only minor chemical differences.

Thirty lactating British Friesian cows were subjected to a 21 d standardization period and were then offered the three silages for 21 d in a randomized‐block design experiment. The animals were stalled individually, offered the silages ad libitum and in addition received 5 kg d−1 of a supplement containing 198 g crude protein kg DM−1. The mean silage DM intake, milk yields and milk fat concentrations during the final 7 d on treatment were 8‐44, 8‐62 and 887 kg d−1; 238, 230 and 25‐1 kg d−1; and 368, 400 and 366 g kg−1 for the control, formic acid‐ and inoculant‐treated silages respectively.

Following the feeding trial, six cows per treatment were subdivided to provide three animals which were offered silage alone, and three offered silage plus 5 kg d‐’supplement. Rumen samples taken after 21 d on these treatments indicated no effect of the inoculant on ruman volatile fatty acid proportions, whereas the use of formic acid resulted in increases in both acetate and butyrate concentrations.

The results from this study support that of the earlier work that this particular inoculant, when used at ensiling, can considerably improve animal performance over that achieved with both untreated and formic acid‐treated silages.
Dry matter yield and nutritive value of four summer annual crops in north‐west Spain (Galicia)
Authors: LLOVERAS JAIME
Published: April 2006

Forage production based on summer annual crops is a common agricultural practice in many areas of the world where the growing season is favourable.

0An investigation was conducted over 3 years to compare the dry matter (DM) yield and quality of four annual crops; maize (Zea mays L.), sunflower (Helianthus annus L.), sudangrass (Sorghum bicolor L. Moensch) and sorghum (Sorghum bicolor L. Moensch) x sudangrass; in two rainfed locations with different summer temperatures in north‐west Spain (Galicia). The crops were compared at three harvest dates; first weeks of August and September and, except for sunflower, at a later silage stage.

The comparative forage yields of each crop varied depending on location and harvesting date, reflecting their suitability for the climate of the location.

At Mabegondo, with relatively mild summer temperatures (16.5 °C), maize throughout summer and sunflower until September produced higher DM yields than sudangrass and sorghum × sundangrass. At this location the silage DM yields for maize, sorghum × sudangrass and sundangrass were respectively 15.2, 9.92 and 7.79 t ha−1. At Puebla de Brollón, where the average temperature from June to September was about 2 °C higher than at Mabegondo, the DM production of the sudan‐type crops were similar to maize, while sunflower was significantly lower at the September harvest. The silage DM yields were: maize 14.07 t ha−1 sorghum x sudangrass, 14.05 t ha−1, sudangrass 12–26 t ha−1.

The in vitro dry matter digestibility (IVDMD) of maize was always higher than that of the other crops, with an average value of 700 g kg−1.

It is concluded that, in north‐west Spain, maize is the most suitable summer crop for maximum yield of good quality forage from the first week of August through to the normal silage stage in October.
Effects of spring defoliation and fertilizer nitrogen on the growth of white clover in ryegrass/clover swards
Authors: DAVIES ALISON , EVANS M. ELEANOR
Published: April 2006

An examination was made of the effects of different spring treatments on the growth of white clover in a ryegrass/white clover sward. Plots were either cut once (in February, March or April) or twice (in February and April) or left uncut. Nitrogen was applied to half of the plots in each instance. The clover was sampled at intervals of approximately 3 weeks from February to June to determine numbers of leaves and growing points and weights of plant parts. Rates of leaf appearance were also observed and estimates were made of total herbage mass from ground‐level cuts.

Percentages of white clover in the herbage were higher in unfertilized than in fertilized plots and in defoliated than in undefoliated plots. The percentage increases that followed defoliation were usually maintained into later regrowth, showing that clover content was not automatically reduced as herbage mass increased. Increases in growing points were recorded after the beginning of April in defoliated unfertilized plots but not in undefoliated fertilized plots or in plots fertilized and defoliated twice during the spring period, in which numbers fell substantially.

Inverse relationships were found between rates of leaf appearance, or the number of green leaves retained per stolon, and herbage mass, whereas heights of clover and grass leaves and the percentage of dry matter allocated to petiole rather than leaf in the clover increased with increasing herbage mass.

We suggest that the observed differences between spring treatments in clover percentage result primarily from their differential effects on the formation and death of tillers and growing points in the early stages of regrowth.
Growth of prairie grass (Bromus willdenowii Kunth) and Westerwolds ryegrass (Lolium multiflorum Lam.) at Wageningen, The Netherlands
Authors: HUME D. E.
Published: April 2006

Herbage quality, yields, tiller and plant populations of ‘Grasslands Matua’ prairie grass and ‘Caramba’ tetraploid Westerwolds ryegrass were investigated in a 2‐year field trial on a sandy soil. Plots were either harvested frequently (five to six cuts per year) or infrequently (four cuts). During the first year, herbage was separated into leaf, vegetative and reproductive pseudostem, and analysed separately.

With very mild winters and adequate water supply, swards had good persistence and production for 2 years. Total yield in the first year (10.5 t DM ha−1) was similar for both species. Yields in the second year were (t DM ha−1) 13.4 and 18 for Matua and 11.1 and 13 for Caramba under frequent and infrequent cutting respectively. Leaf contributed 58% to yields and reproductive pseudostem 35%. Infrequently cut plots had: 23% higher dry matter yields, primarily due to higher yields of reproductive pseudostem; higher yields of most chemical components and higher contents of water‐soluble carbohydrates and cell walls; lower digestibility and nitrogen content. Cell wall content was consistently higher in Matua but otherwise herbage quality was similar for the two species. It is suggested that prairie grass should be considered as a replacement for spring‐sown Westerwolds ryegrass on sandy soils in The Netherlands.
Herbage production and nitrogen recovery from slurry injection and fertilizer nitrogen application
Authors: LONG F. N. J. , GRACEY H. I.
Published: April 2006

An experiment was carried out during 1986 and 1987 to examine the effects of mid‐season slurry injection and fertilizer‐nitrogen (N) application on herbage dry matter (DM) yield and N recovery. Cattle and pig slurry were injected at 56 and 112 m3 ha−1 into an established sward. Five rates of fertilizer‐N, as calcium ammonium nitrate, ranging from 0 to 120 kg ha−1 in 30‐kg increments, were superimposed on these treatments, and in both years DM yield was measured in one cut after 70 d regrowth. Slurry treatments increased herbage DM yields significantly (P < 0‐001). The efficiency of slurry total N compared with calcium ammonium nitrate‐N averaged 53% in 1986 and 86% in 1987. The mean apparent recovery of slurry total N in herbage was 55% in 1986 and 40% in 1987. Fertilizer‐N application increased (P < 0.001) the mean yields of herbage in both years but when combined with some of the slurry treatments, DM yields over the five N‐levels did not differ significantly, giving rise to interactions in 1986 (P < 0‐001) and 1987 (P < 001). It is concluded that mid‐season injection of slurry can be an effective means of utilizing slurry‐N in terms of herbage DM production and consequent N use.
The effect of nitrogen in cattle slurry and mineral fertilizers on nitrogen fixation by white clover
Authors: NESHEIM L. , BOLLER B. C. , LEHMANN J. , WALTHER U.
Published: April 2006

The influence of N in slurry or in mineral fertilizers on herbage yield and nitrogen fixation by white clover grown in mixed swards was investigated. Two levels of N in cattle slurry were compared with a range of mineral N fertilization. The percentage of N derived from symbiosis (% Nsym) was measured by the 15N‐isotope dilution method. The measurements were made in spring 1987 in two 4‐year‐old field trials, and included two out of five harvests.

The % Nsym was approximately 90% without N fertilization. It decreased in response to both mineral N and N in slurry but did not fall below 63%. The sum of two harvests revealed that 51·2 kg N ha−1 were fixed in the absence of N fertilization. With 75 kg mineral N ha−1 or 50 m3 cattle slurry ha−1, the yield of fixed N decreased to 17·2 and 24·9 kg ha−1, respectively. When compared on the basis of the fertilizer effect on dry matter yield and N concentration of perennial ryegrass, the decrease in yield of N fixed due to treatment with cattle slurry was less than that due to mineral N fertilizer. This was owing to the smaller extent of the depression in the proportion of white clover in the sward when the same amount of N was applied in cattle slurry, as compared with mineral fertilizer, although % Nsym responded similarly to both types of N fertilization.