A comparison of Italian ryegrass (Lolium multiflorum), hybrid ryegrass (Lolium perenne × L. multiflorum) and timothy (Phleum pratense) under different systems of management

An Italian ryegrass (cv. RvP), a tetraploid hybrid ryegrass (Sabrina), and an early heading timothy (Scots), were compared under 3-cut silage plus aftermath, 5-cut early bite-hay-aftermath and 6-cut simulated grazing managements over 2 harvest years 1974–75. Annual nitrogen applications totalled 375 kg ha^?1 N for the silage and grazing systems and 325 kg ha^?1 for the early bite-hay-aftermath treatment. In 1974, the first harvest year, RvP and Sabrina outyielded Scots timothy. In the dry summer of 1975 the drought tolerance and persistency of Sabrina was superior to RvP, but both grasses gave low yields (approx. 10·0 ha^?1 DM under the conservation managements) and showed a marked fall in production compared with the first year, by RvP of 35% and by Sabrina of 25%. Scots timothy in the second year equalled the ryegrass in total DM yield under the hay management system. Over the 2 years RvP and Sabrina gave similar yields, which were 10% better than Scots timothy, under all managements. RvP and Sabrina are equally suitable for silage production, but second and third silage cuts of RvP require shorter regrowth periods than Sabrina for good quality herbage. Sabrina will also provide leafier grazing than RvP.     

Forage production by two Lotus species as influenced by companion grass species

A small-plot experiment was carried out with grass-lotus (Lotus spp.) swards on a lowland (185 m) clay-soil site in S-W England. Two species of lotus (Lotus corniculatus cv. Leo and L. pedunculatus, syn, L. uliginosus, cv. Maku) were each sown at 10 kg seed ha^?1 with lour grass species each at two grass-seed rates: Festuca pratensis at 6 or 3 kg ha^?1 and Phleum pratense, Agrostis capillaris and Poa pratensis at 4 or 2 kg ha^?1. Assessments were made over three harvest years (1992–94). during which no fertilizers were applied. Mean total herbage dry matter (DM) harvested from cv. Leo swards was 90 t ha^?1 in year 1, 8–9 t ha^?1 in year 2 and 4 0 t ha^?1 in year 3. and from cv. Maku swards 6–6 t ha^?1 in year 1. 8–9 t ha^?1 in year 2 and 3–9 t ha^?1 in year 3. Highest three-year mean total yields were with F. pratensis as the companion grass (7–4 t ha^?1 year^?1), followed by Phleum pratense (7–0 t ha^?1), A. capillaris (6–9 t ha^?1) and Poa pratensis (6–2 t ha^?1). The lower grass-seed rate resulted in a greater proportion of lotus in the total harvested DM in year I. The higher grass-seed rate resulted in higher yields from F. pratensis swards in year 1, but there were no significant effects for other species or in subsequent years. Lotus as a proportion of harvested DM declined from about 70% in year 1 to about 20% in year 3. The mean DM yield of lotus herbage in years 1, 2 and 3, respectively, was 5–5, 2–8 and 0–8 t ha^?1 from cv. Leo swards, and 4–0, 3–3 and 0–8 t ha^?1 from cv. Maku swards. Lotus herbage was of higher digestibility from cv. Leo [digestible organic matter (DOM) of 661 g kg^?1 of lotus DM] compared with cv. Maku (551 g kg^?1 DM). Mean N content of lotus herbage was 35 g N kg^?1 DM. Digestibility of companion grass herbage was highest for Phleum pratense (557 g kg^?1 DM) and lowest for A. capillaris (493 g kg^?1 DM). It is concluded that lotus may be an alternative legume to white clover for low-input, low-fertility situations. However, further research is needed to evaluate its performance on different sites and under different management regimes, particularly grazing, and to overcome the apparent problems of its persistence.     

Herbage and nitrogen yields,fixation and transfer by white clover to companion grasses in grazed swards under different rates of nitrogen fertilization

In grass–legume swards, biologically fixed nitrogen (N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to companion grasses under intensive grazing at a site with high soil‐N status. During a 3‐year period (2011–2013), swards of perennial ryegrass and of perennial ryegrass–white clover, receiving up to 240 kg N ha^?1 year^?1, were compared using isotope dilution and N‐difference methods. The presence of white clover increased herbage and N yields by 12–44% and 26–72%, respectively. Applications of N fertilizer reduced sward white clover content, but the effect was less at below 120 kg N ha^?1. The proportion of N derived from the atmospheric N fixation was 25–70%. Nitrogen fixation ranged from 25 to 142 kg N ha^?1 measured using the isotope dilution method in 2012 and from 52 to 291 kg N ha^?1 using the N‐difference method across all years. Fertilizer N application reduced the percentage and yield of fixed N. Transfer of N from white clover to grass was not confirmed, but there was an increased N content in grass and soil‐N levels. Under intensive grazing, the maximum applied N rate that optimized herbage and N yields with minimal effect on white clover content and fixation rates was 60–120 kg N ha^?1.     

The influence of date of sowing and seed rate on the production of pure-sown red clover

Hungaropoly tetraploid broad red clover was sown at seed rates of 6, 12 or 18 kg ha^-1 on six dates from April to September 1971. Three crops were harvested in 1972 and one in June 1973. In 1972, total herbage dry matter yields ranged from 5.22 to 12.22 t ha^-1 and red clover dry matter yields from 3.61 to 11.92 t ha^-1 when meaned over all seed rates. April to July sowing dates gave significantly higher yields than later sowings. In general, August and September sowings gave the lowest red clover contents in a range from 63.2 to 96.5%, the highest digestibilities within a range 61.9 to 65.0% and the lowest crude protein contents in a range 15.5 to 17.3%. The influence of seed rate was less marked than sowing date. Mean annual yields of total herbage dry matter increased from 9.88 to 10.85 t ha^?1 as seed rate was increased from 6 to 18 kg ha^?1. Red clover dry matter yields and contents of red clover and crude protein in the total herbage also followed this trend. The sowing date effects on total herbage yield and content of red clover did not persist into the second harvest year but the seed rate effects were still noticeable. Plant numbers in spring the first harvest year and hence percentage survival from sowing were depressed by late sowing; plant numbers rose but percentage survival declined as seed rate was increased. The seed rate effects on plant population persisted until spring of the second harvest year but sowing date effects did not. Better stands of red clover were obtained from sowings made between April and June, when a seed rate of 12 kg ha^?1 was adequate. The adverse effects of late sowing cannot be fully compensated by raising seed rates of clover. There was a significant interaction between seed rate and date of sowing. For April-May sowings, seed rate was not critical. Thereafter, a linear effect of seed rate on yield was discernible.     

The response of a perennial ryegrass (Lolium perenne L.) seed crop to nitrogen fertilizer application in the absence of moisture stress

Responses of perennial ryegrass (Lolium perenne L.) to nitrogen (N) fertilizer application rates and timings vary widely, because water is often limiting. Yield response to N fertilizer application during autumn, late‐winter and spring, and the associated efficiency of use of these inputs, was assessed under conditions of non‐limiting soil moisture during two, one‐year lysimeter studies in Canterbury, New Zealand. There were significant (P < 0·05) increases in seed and herbage yields with increasing N fertilizer application. Seed yields differed with year; greatest yields were 300 g m^?2 in 1996 and 450 g m^?2 in 1997. Seed head numbers (r²=0·77), seeds head^?1 (r²=0·92) and herbage yield (r²=0·92) were the major determinants of seed yield in both years. Irrigation required to maintain the soil between 70% and 90% of field capacity was directly related (r²=0·94 and 0·99 in 1996 and 1997 respectively) to increases in herbage yield. Seed yield, seed quality (thousand seed weight and percentage of seed > 1·85 mg), efficiency of water use, efficiency of N fertilizer use and apparent N fertilizer recovery were greatest when N fertilizer was applied at a rate of 50 kg N ha^?1, 50 or 100 kg N ha^?1 and 150 kg N ha^?1 in autumn, late‐winter and spring respectively; further increases in spring N fertilizer stimulated vegetative growth, but not seed yield. As a management strategy, applying N fertilizer to match the N requirements of the crop during the reproductive stage of growth will result in high yields of high quality seed while minimizing environmental impact.     

The effects on ewes and lambs of grazing pasture containing differing levels of nitrate-nitrogen

Perennial ryegrass (Lolium perenne) swards were given annual applications in six equal instalments at 21-day intervals of either 100, 400 or 700 kg ha^?1 N in 1973 and 1974. Ewes with twin lambs were rotationally grazed on these areas. The nitrate-N content of the grass was measured immediately before grazing. Blood samples were taken at regular intervals from the ewes and lambs to estimate blood methaemoglobin and certain plasma mineral concentrations. A maximum nitrate-N concentration of of 0.67% in the herbage dry matter was recorded but no adverse effect of N fertilizer was found in terms of the blood constituents or growth of the sheep, or in the carcase quality of the lambs.     

Nitrogen concentrations in the cell wall and lignocellulose of smooth homegrass herbage*

Applying nitrogen (N) fertilizer to grass generally increases N concentration in herbage. Not as well documented, however, are N fertilizer effects on concentrations of N in plant cell walls and lignocellulose. The objective four study was to ascertain how N fertilizer applied with or without a nitrification inhibitor would affect N concentrations in the cell wall (neutral-detergent fibre (NDF)) and lignocellulose (acid-detergent fibre (ADF)) of smooth bromegrass (Bromus inermis Leyss). Nitrogen fertilizer ((NH₄)₂SO₄) was applied at 0, 125, or 230 kg N ha^?1 in combination with 0, 2–5, or 50 kg ha^?1 of nitrapyrin (2- chloro-6-(trichloromethyl) pyridine) to smooth bromegrass in April of 1985 and 1986. Herbage was harvested at 2, 4, 6 and 8 weeks after treatment. Freeze-dried herbage samples were analysed for in vitro digestible dry matter (IVDDM), total N, and N in neutral- and acid-detergent fibre (NDFN and ADFN, expressed as g kg^?1 NDF and ADF, respectively). Nitrapyrin had no effect on IVDDM, total N, NDFN or ADFN, Nitrogen fertilizer increased concentrations of total N in herbage dry matter, and increased N concentrations in NDF and ADF. Most of the increase in total N concentration occurred in the neutral-detergent soluble portion. When NDFN and ADFN concentrations were expressed on a total N basis (g k g^?1 of total N), N fertilizer had no effect. Available fibre N (AFN; calculated as NDFN minus ADFN, each expressed as g kg^?1 total N) was not affected by N fertilizer. The average AFN concentration was 93 g kg^?1 total N. Nitrogen fertilizer did not affect herbage quality; however, age of herbage had marked effects on herbage quality.     

The effect of initial spring grazing date and subsequent stocking rate on the grazing management, grass dry matter intake and milk production of dairy cows in summer

The objective of this study was to investigate the effects of an early (February; F) or delayed (April; A) primary spring grazing date and two stocking rates, high (H) and medium (M), on the grazing management, dry matter (DM) intake of grass herbage and milk production of spring‐calving dairy cows grazing a perennial ryegrass sward in the subsequent summer. Sixty‐four Holstein‐Friesian dairy cows (mean of 58 d in milk) were assigned to one of four grazing treatments (n = 16) which were imposed from 12 April to 3 July 2004. Cows on the early spring‐grazing treatment were grazed at 5·5 cows ha^?1 (treatment FH) and 4·5 cows ha^?1 (treatment FM) while cows on the late‐grazing treatment were grazed at 6·4 cows ha^?1 (treatment AH) and 5·5 cows ha^?1 (treatment AM). The organic matter digestibility and crude protein concentration of the grass herbage were higher on the early‐grazing treatment than on the late‐grazing treatment. The cows on the FM treatment had significantly (P < 0·001) higher milk (24·5 kg), solids‐corrected milk (22·5 kg), fat (P < 0·01, 918 g) and protein (831 g) yields than the other three treatments. Cows on the FM treatment had a higher (P < 0·001) DM intake of grass herbage by 2·3 kg DM per cow per day than cows on the AH treatment, which had a DM intake significantly lower than all other treatments (15·2 kg DM per cow per day). The results of the present study showed that grazing in early spring has a positive effect on herbage quality in subsequent grazing rotations. The study also concluded that early spring‐grazed swards stocked at a medium stocking rate (4·5 cows ha^?1; FM) resulted in the highest DM intake of grass herbage and milk production.     

Seeding cool-season grasses into unimproved warm-season pasture in the southern Great Plains of the United States

Limited availability of herbage during the cool season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six cool‐season grasses were individually sown into clean‐tilled ground, no‐till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no‐till over‐sown into dormant unimproved warm‐season pastures. The dry matter (DM) yields of mixtures of cool and warm‐season herbage species were measured to test their potential for increasing cool‐season herbage production in a low‐input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year‐round DM yields than undisturbed warm‐season pasture with all establishment methods. When cool‐season grass was no‐till seeded into existing warm‐season pasture, there was on average a 0·61 kg DM increase in year‐round herbage production for each 1·0 kg DM of cool‐season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean‐tilled ground, required 700 or 1400 kg DM ha^?1, respectively, of cool‐season production before the year‐round DM yield of each species equalled that of undisturbed warm‐season pasture. Productive pastures of perennial cool‐season grasses were not sustained beyond two growing seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of cool‐season perennial grasses for over‐seeding unimproved warm‐season pasture in the southern Great Plains.     

Response of Stipa bungeana and Pennisetum flaccidum to urine of sheep in steppe grassland of north‐western China

Urine [12·3 g nitrogen (N) L^?1], collected from native Tan sheep in rangeland of the Loess Plateau in north‐western China, was applied to vegetation patches dominated by Stipa bungeana (C₃ grass) or Pennisetum flaccidum, (C₄ grass) at either 0, 1·0, 2·0 or 4·0 L urine m^?2 in early‐, mid‐, or late‐growing season, and herbage mass and tiller number per sample recorded, allowing calculation of the respective contributions of increases in tiller weight and tiller density to the response from N in urine. Such records were made three times in the growing season of application of urine, and at the end of the following growing season. Responses to urine were of the order of 1 and 5 kg herbage DM kg^?1 N applied for S. bungeana and P. flaccidum, respectively. Except for early‐season application, responses of S. bungeana were mainly expressed in the season following urine application whereas responses of P. flaccidum tended to be expressed within the year of urine application, although with a residual response in the following year. The general pattern was for a tiller density‐mediated response in the period immediately after application, followed later by a tiller weight‐mediated response. Taken together with other recent research, S. bungeana can be considered a stress‐tolerating species with a limited response to N application and P. flaccidum an opportunist species able to capitalize on increased N supply.     

Effect of herbage mass per unit area and conditioning treatment on herbage drying rate

The rates of drying of herbage, cut from perennial ryegrass (Lolium perenne L.) – dominant swards and subjected to different treatments, were investigated under field conditions by changes in weight of herbage in wire mesh trays in 1995 and 1996. A series of replicated factorial experiments studied the effects, in different combinations, of intensity of conditioning achieved by passing the cut herbage through a laboratory‐scale macerator zero (0C), once (1C), three (3C) or six (6C) times; weight of herbage per unit area equivalent to 450, 675 and 900 g dry matter (DM) m^?2. In one experiment, pressing the herbage to form a mat was incorporated into the experimental design. A further experiment investigated the effect of varying the proportion of conditioned herbage in the herbage mass from 0·00, 0·25, 0·50, 0·75 and 1·00 on drying rate. On each occasion the trays plus herbage were weighed at hourly intervals over an ≈6‐h period and the DM content of the herbage estimated from the change in weight. On all occasions, conditioning and weight of herbage per unit area significantly (P < 0·001) influenced herbage drying rate. Lowering the weight per unit area of both unconditioned and conditioned herbage increased the rate of moisture loss. Unconditioned herbage at the equivalent of a herbage mass of 450 g DM m^?2 had a total moisture loss that was on average 1·5–1·8 times greater than unconditioned herbage at the equivalent of a herbage mass of 900 g DM m^?2. Similarly, conditioned herbage at the equivalent of a herbage mass of 450 g DM m^?2 had a total moisture loss that was 1·8–2·3 times greater than unconditioned herbage at the equivalent of a herbage mass of 900 g DM m^?2. Increasing the level of conditioning produced a non‐linear response in rate of moisture loss, consequently 3 passes through the macerator produced >0·95 of the total moisture loss that was produced by 6 passes through the macerator. Increasing the proportion of conditioned herbage in the herbage mass increased rate of moisture loss and consequently final DM content (P < 0·001) although there was little effect from increasing the proportion of conditioned herbage above 0·75. The effects of conditioning and weight of herbage per unit area treatments on total nitrogen , water‐soluble carbohydrate and acid‐detergent fibre concentration of the herbage were small.     

Performance of white clover/perennial ryegrass mixtures under cutting

Clover persistence in mixtures of two varieties of perennial ryegrass (Lolium perenne) with contrasting growth habits and three white clover (Trifolium repens) varieties differing in leaf sizes was evaluated at two cutting frequencies. An experiment was sown in 1991 on a clay soil. The plots received no nitrogen fertilizer. In 1992, 1993 and 1994, mixtures containing the large-leaved clover cv. Alice yielded significantly more herbage dry matter (DM) and had a higher clover content than mixtures containing cvs Gwenda and Retor. Companion grass variety did not consistently affect yield or botanical composition. Cutting at 2 t DM ha^?1 resulted in slightly higher total annual yields than cutting at 1.2 t DM ha^?1, but did not affect clover content. In 1992 the mixtures yielded, depending on cutting frequency and variety, 10·6–14·6 t DM ha^?1 and 446–599 kg ha^?1 N, whereas grass monocultures yielded only 1·2–2·0 t DM ha^?1 and 25–46 kg ha^?1 N. From 1992 to 1994 the annual mean total herbage yield of DM in the mixtures declined from 12·2 to 10·5 to 8·7 t ha^?1, the white clover yield declined from 8·7 to 6·5 to 4·1 t ha^?1 and the average clover content during the growing season declined from 71% to 61% to 46%, whereas the grass yield increased from 3·4 to 4·0 to 4·5 t ha^?1. The N yield decreased from 507 to 406 to 265 kg N ha^?1 and the apparent N fixation from 470 to 380 to 238 kg N ha^?1. Nitrate leaching losses during the winters of 1992–93 and 1994–95 were highest under mixtures with cv. Alice, but did not exceed 10 kg N ha^?1. The in vitro digestible organic matter (IVDOM) was generally higher in clover than in grass, particularly in the summer months. No differences in IVDOM were found among clover or grass varieties. The experiment will be continued to study clover persistence and the mechanisms that affect the grass/clover balance.     

The effects of defoliating grass in winter or spring on herbage yields and ensilage characteristics

Under Irish conditions, the digestibility in May of grass managed for silage production is sometimes lower than expected. In each of two successive years, replicate field plots were established to examine the effects of three defoliation heights (uncut or cut to a stubble height of 10 or 5 cm) applied in winter and/or spring on herbage yields harvested in May and again in July, and on chemical composition and conservation characteristics associated with first‐cut silage. Swards that were not defoliated in December or March had a dry‐matter (DM) yield and in vitro DM digestibility (DMD) in mid‐May of 6597 kg ha^?1 and 736 g kg^?1, respectively, in Year 1, and corresponding values of 7338 kg ha^?1 and 771 g kg^?1 in Year 2. Defoliating swards to 5 cm in December reduced (P < 0·001) May DM yields compared to swards that were not defoliated in both December and March, while herbage DMD in May increased (P < 0·001) when defoliated in December or March. There were no clear effects of defoliation height or its timing on herbage ensilability or resultant conservation efficiency characteristics. The effects of defoliation on July yield were the reverse of those observed for May, while the total yield of the December and March defoliations plus the two silage harvests increased as defoliation height was lowered in Year 2 only. It is concluded that defoliation in winter and/or spring can increase herbage digestibility but will likely reduce DM yields in May.     

Negative effects of winter- and spring-applied cattle slurry on the yield of herbage at simulated early grazing and first-cut silage

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

Effect of fertilizer nitrogen source and cattle slurry on herbage production and nitrogen utilization

A field plot experiment was carried out on an established grassland sward from 1983–88 inclusive to examine the effects of time of application, chemical form of nitrogen (N) and cattle slurry dry matter (DM) content on yield and efficiency of N use. Four forms of fertilizer N (a semi-organic fertilizer, a combined 2.1:1 (w/w) semi-organic/calcium ammonium nitrate (CAN) fertilizer, CAN and urea, each supplying 300 kg N ha^?1 year^?1, were applied with or without unseparated or separated cattle slurry at 93 and 73 g kg^?1 DM respectively, both supplying approximately 150 kg N ha^?1 year^?1. All fertilizers and slurries were applied in three equal dressings (February/March, May/June and July/August). The efficiency of use of fertilizer and slurry N was evaluated by measuring DM yield, N uptake and apparent recovery of N in herbage at all harvests during each growing season. Fertilizer N application significantly increased (P<0.001) the mean yields of herbage at each harvest in all years. The form of fertilizer N had no significant effect (P>0.05) on first harvest and total herbage yields, nor on N uptakes by herbage at the first harvest in any year. The performance of urea and of CAN was more variable at the second and third harvests relative to that of the semi-organic or combined 2.2:1 (w/w) semi-organic/CAN sources which had similar efficiencies of N use. Lower DM production was associated with reduced uptake of N. Values for mean overall apparent recovery of N ranged from 57.9 ± 2.67% for the semi-organic fertilizer to 50.2±3.05% for CAN. Unseparated cattle slurry and separated cattle slurry produced similar herbage yields and N responses that were lower and more variable than with fertilizer N. The overall mean apparent recovery of N from unseparated cattle slurry was 25.5 ± 5.03% compared to 5.0 ± 4.74% for separated cattle slurry. Efficiency of N use was highest with spring applications and least with mid-season applications. Recoveries ranged from ?29% for separated cattle slurry applied in June 1984 to 56% for unseparated and separated cattle slurry applied in February 1988 and June 1987 respectively. No interactions were recorded between cattle slurry and fertilizer N in terms of DM production or N uptake by herbage. The results of this study support the use of a fertilizer N source, selected on a least-cost basis, in combination with slurry to promote spring herbage production. For subsequent production, N should be supplied in fertilizer form only. The use of urea is risky under low rainfall conditions. Mechanical separation did not improve the efficiency of use of slurry N.     

Relationship of bite mass of cattle to sward structure of four temperate grasses in short‐term grazing sessions

The effect of sward structure of four temperate grass species on the bite mass of cattle was evaluated. Micro‐swards (79 cm × 47 cm; approximately the area of a feeding station) of orchardgrass (Dactylis glomerata L.), quackgrass [Elymus repens (L.) Gould], meadow fescue [Schedonorus pratensis (Huds.) P. Beauv] and reed canarygrass (Phalaris arundinacea L.) were offered to Holstein dairy cows in short‐term grazing sessions in 2006 and 2007 using a 4 × 4 Latin square design. Cows were allowed to take fifty bites in each session. Bite mass was calculated by dividing the adjusted change in weight of the micro‐sward by the number of bites. Sward surface height, bulk density and distribution of herbage dry matter (DM) in the canopy were measured pre‐ and post‐grazing. Sward structure differed among the grass species within years but bite mass (on a fresh or DM basis) was not affected. Higher surface heights and bulk densities in 2006 compared with 2007 (averaged across grass species) resulted in greater bite masses of DM in 2006. Values were 25·7 cm vs. 17·0 cm for surface height; 1219 g m^?3 vs. 926 g m^?3 for bulk density; and 1·05 g DM bite^?1 vs. 0·50 g DM bite^?1 for 2006 and 2007 respectively. Within the context of this study, differences between years in bite mass, associated with greater changes in sward structure, were more important than differences among grass species.     

Dietary cation–anion difference and cadmium concentration in grasses fertilized with chloride

High dietary cation–anion difference (DCAD) of grass herbage increases the occurrence of hypocalcaemia of dairy cows. Application of chloride fertilizer reduces DCAD of herbage but it could increase cadmium concentration in herbage. This study includes an experiment conducted in Australia and in Canada. A glasshouse experiment in Australia evaluated the effect of four rates of chloride application (0–240 kg ha^?1) on values of herbage DCAD and cadmium concentration of above‐ground plant material of timothy (Phleum pratense L.) and phalaris (Phalaris aquatica L.), harvested 6 weeks after sowing and grown on two soils that had received cadmium either as a contaminant in superphosphate (soil + Super) or in sewage biosolids (soil + Bio) along with respective control soils (soil 0 Super and soil 0 Bio). Application of chloride fertilizer decreased values of herbage DCAD by 349 mmol_c kg^?1 dry matter (DM). Herbage DCAD values were highest on the 0 Bio soil (739 mmol_c kg^?1 DM) and were not different among the three other soils. Species did not differ in herbage DCAD values. Cadmium concentration in the above‐ground plant material was highest on the +Bio soil treatment (1·67 mg kg^?1 DM) and was lower for the three other soil treatments. Above‐ground plant material of phalaris had a higher cadmium concentration than that of timothy. Application of chloride fertilizer did not affect cadmium concentration in above‐ground plant material, despite the high cadmium content of the soil on the +Bio treatment. The field experiment in Canada evaluated the effect of four rates of chloride application (0–144 kg ha^?1) on cadmium concentration of a timothy‐based grass sward grown on four sites with soils of different potassium content. Application of chloride fertilizer increased cadmium concentration of herbage at two of the four sites but the maximum increase in cadmium concentration was only 0·025 mg kg^?1 DM. Chloride fertilizer can be applied to decrease forage DCAD with minimal risk of increasing Cd in the food chain.     

Effect of a stay-green locus on the dry-matter yield, nitrogen yield and shoot density of perennial ryegrass

A rare stay‐green allele transferred from meadow fescue (Festuca pratensis L.) to perennial ryegrass (Lolium perenne L.) has improved both the colour of turf and the nutritive value of herbage. In this study its effect on shoot density and forage yield was assessed. Equivalent populations of perennial ryegrass were constructed with and without the stay‐green allele, following eight generations of backcrossing to perennial ryegrass. The stay‐green population, the normal population and the cv. AberStar were compared over two harvest years (2005 and 2006) in a field experiment with six application rates of N fertilizer (100, 200, 300, 400, 500 and 600 kg ha^?1 annually). There were no significant interactions between level of N fertilizer and population in any of the traits measured. The mean annual dry‐matter (DM) yield over all populations and fertilizer levels was 6·45 t ha^?1 lower in the second harvest year. Mean annual DM yields over all fertilizer levels of the normal population were higher than, or equal to, AberStar while those of the stay‐green population were significantly (proportionately 0·10–0·13) lower than the normal population. In 2005, the mean total yield of N in the herbage of the stay‐green population was 0·09 lower than that of the normal population and the mean concentration of N over all harvests was 1·5 g kg^?1 DM higher. The shoot density of the stay‐green population after the last harvest in November 2006 was 0·18 lower than that of the normal population (3689 and 4478 shoots m^?2 respectively).     

Manipulation of herbage production by altering the pattern of applying nitrogen fertilizer

The redistribution of herbage production during the growing season to synchronize herbage supply with feed demand by livestock by altering the application pattern of a range of nitrogen (N) fertilizer rates was studied. Application rates of N were 50, 150 and 250 kg N ha^?1 per annum and patterns were with 0·60 of N fertilizer applied before June (treatment RN) and with only 0·20 of N fertilizer before June (treatment IN). Treatments were imposed in a cutting (simulated grazing) experiment (Experiment 1), which was conducted for 2 years and a grazing experiment (Experiment 2) which was conducted for 3 years. In both experiments, herbage production was reduced in April and May and increased in the June–October period on treatment IN relative to RN, but annual herbage production was not significantly affected except in the third year of Experiment 2, when treatment RN had significantly (P < 0·05) higher herbage production than treatment IN. Crude protein (CP) concentration of herbage was lower in April and May on treatment IN than treatment RN. However, CP concentration of herbage was rarely below 150 g kg^?1 DM and so it is unlikely that livestock productivity would be compromised. On treatment IN, concentrations of CP in herbage were higher in the late summer than on treatment RN, which may increase livestock productivity during July and August when livestock productivity is often lower. Altering the strategy of application of N fertilizer did not affect in vitro dry matter digestibility of herbage.     

Seasonal productivity and nutritive value of temperate grasses found in semi-natural pastures in Europe: responses to cutting frequency and N supply

Monocultures of thirteen perennial C₃ grass species that co‐occur in temperate semi‐natural grassland communities in Europe were compared in a factorial field design of two levels of N supply and two levels of cutting frequency. Above‐ground yield of dry matter (DM), crude protein (CP) concentration and pepsin‐cellulase DM digestibility of herbage were measured in two successive years. Species was the largest source of variability in yield of DM and DM digestibility of herbage, while CP concentration of herbage responded more to management factors. The highest mean DM yields and values of DM digestibility of herbage were achieved in spring for Festuca arundinacea and in autumn for Phleum pratense. Poa trivialis and Festuca rubra had the lowest DM yield and DM digestibility values, respectively, regardless of seasons and treatments. For all species CP concentration in herbage increased in response to an increase in cutting frequency and N supply by an average of 46 and 34 g kg^?1 DM respectively. Differences between years and seasons indicated the importance of plant phenology on nutritional variables and the influence of environmental factors on species performance. Species ranking was compared according to their annual digestible DM and CP yields. The results show that some grasses have a nutritive value which is comparable to that of forages selected for high yields.