bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of fertilizer nitrogen rate, white clover variety and closeness of cutting on herbage productivity from perennial ryegrass/white clover swards
Authors: FRAME J. , BOYD A. G.
Published: April 2006

Four varieties of white clover (small‐leaved cv. Aberystwyth S184. medium‐leaved cv. Grasslands Huia and large‐leaved cvs Linda and Olwen) were sown at 3 kg ha‐1 together with 10 kg ha‐1 perennial ryegrass cv. Talbot. Herbage productivity was measured for three harvest years, 1979‐81, over four annual rates of fertilizer N (0,120,240 and 360 kg ha‐1) and two closeness of cutting treatments (80 and 40 mm from ground level). A simulated grazing regime of six cuts per year at 3‐ to 6‐week intervals was used.

Production of total herbage DM was increased by increasing N rate; mean annual DM production ranged from 783 1 ha‐1 with no N to 11701 ha‐1 at 360 kg ha‐1 N. Mean herbage response to N (kg DM per kg N applied) was 73,90 and 108 for the three successive N increments relative to no N. Mean white clover DM production was reduced from 4 14t ha‐1 with no N to 051 t ha‐1 at 360 kg ha‐1 N.

The large‐leaved clover varieties were more productive than the small‐ or medium‐leaved varieties at all N rates. Close cutting increased total herbage and white clover by a mean annual 16% and 31%. respectively. White clover varieties did not interact with either N rate or closeness of cutting.

It is concluded that repetitive N application over the growing season is incompatible with white clover persistence and production, even with large‐leaved clover varieties or with close cutting, two factors which improved clover performance in the experimental swards.
Slot‐seeding investigations. 5 The effects of simulated delayed emergence and propyzamide on the spread and growth of white clover in permanent pasture
Authors: WILLIAMS E.D. , HAYES M. J.
Published: April 2006

The effects of delayed emergence of white clover (cv. Grasslands Huia) seedlings, following slot‐seeding during spring and early summer 1983, were simulated by sowing seeds at intervals into slots cut in turves of permanent grassland in soil‐filled tanks or in the field. The resulting spread and growth of the species were assessed during the following 15–18 months. The effects of propyzamide, a grass‐suppressing herbicide (at 0·2 kg ha‐1), were also investigated in the field.

A delay of 10 or 18 days in the sowing of seeds in turves in the tanks reduced clover dry weight yield from 23 to 11 during 1983 and from 118 to 96 g (0·12 m)‐2 during 1984. Spread of stolons from the slots was also greatly delayed and effects persisted for at least a year. Increased clover growth on the earliest sown treatment more than compensated for a slightly smaller yield of grass.

In the field, yields of clover from late summer 1983 until spring 1984 closely reflected the order of emergence. Afterwards, differences were less clear‐cut but the cumulative yield of clover until August 1984 of the earliest‐sown treatment was twice that of a treatment sown 20 d later. Effects of delayed sowing in summer 1983 were more pronounced on stolons than on foliage growth when measured in September 1984, with significant reductions in many stolon attributes even with 8 d delay in sowing. Application of propyzamide in autumn 1983 increased clover yield during 1984 from 1·7 to 3·0 and total herbage yield from 7·1 to 8·6 t ha‐1.

The results demonstrated some of the benefits of rapid seedling emergence and of the use of a grass‐suppressing herbicide, but did not indicate any interaction between the two factors.
The invertebrate fauna of grassland and its influence on productivity. II. Factors affecting the abundance and composition of the fauna
Authors: CURRY J. p.
Published: April 2006

The main factors affecting the abundance and composition of the invertebrate fauna in grassland are reviewed. Old grasslands with species‐rich swards and complex structure support an abundant and diverse fauna compared with uniform leys with few species. Seasonal and successional changes in the sward are accompanied by equally marked changes in the invertebrate community. Climate and weather have a major influence, but their effects may be modified locally by the availability of shelter. Soil physical and chemical characteristics influence the soil fauna directly and the above ground fauna indirectly through the vegetation. Food quality as determined by physical and chemical plant characteristics strongly influences invertebrate growth, reproduction and mortality. The main biotic factors affecting abundance are natural enemies and disease; these, in combination with weather and food quality, are often the main agents in determining population density in natural communities.

Management practices such as grazing, cutting, fertilizer application, burning, soil water control and pesticide use profoundly influence the sward and induce correspondingly great changes in the invertebrate community.
The effects of weather and nutrition on the yield of hay from Palace Leas meadow hay plots, at Cockle Park Experimental Farm, over the period from 1897 to 1980
Authors: COLEMAN S. Y. , SHIEL R. S. , EVANS D. A.
Published: April 2006

The yield of hay on the Palace Leas meadow hay plots has increased significantly with time on the higher yielding plots but has remained constant on the lower yielding plots. Yield on the higher yielding plots shows a relatively low fluctuation from year to year, and yields of plots treated with farmyard manure show high intercorrelations with each other, but lower correlations with the other plots. Yield is influenced by weather, but even the most successful climatic parameter– maximum soil moisture deficit—only accounts for 30% of the year on year variation in yield. There are highly significant autocorrelations between yields within each of the farmyard manure, treated plots indicating cyclic effects with periods of up to 6 years, but these are not related to the cyclic patterns of manure application.
The introduction of red or white clover into a perennial grass sward
Authors: CURLL M. L. , GLEESON A. C.
Published: April 2006

Sowing and post‐sowing management techniques were assessed for their effectiveness in introducing Trifolium repens and T. pratense into an established Phalaris aquatica sward in spring and autumn.

Percentage emergence, seedling survival, seedling weight and final clover content were greater with T. pratense than with T. repens. Surface sowing gave 10% emergence compared to 62% for tilled treatments. Rotary sowing gave superior emergence in autumn, while tined sowing gave superior emergence in spring. However, seedling survival and weight, and therefore final clover content, were generally greater with rotary sowing than with tined sowing.

The removal of competition from the resident grass by bandspraying with glyphosate prior to sowing, and repeated lenient defoliation postsowing, increased final seedling numbers by 19% and 46%, respectively, and their individual weight by 29% and 82%, respectively.

The results showed that direct sowing in spring or autumn can be used to restore successfully a substantial population of clover plants to an existing perennial grass sward. They also demonstrated the importance of management to manipulate the environment of the developing clover plant.
Effect of commercial inoculant and formic acid± formalin silage additives on silage fermentation and intake and on liveweight change of young cattle
Authors: HAIGH P. M. , APPLETONT M. , CLENCH S. F.
Published: April 2006

Data from six experiments conducted at two Agricultural Development and Advisory Service Experimental Husbandry Farms during 1980–83 were used to compare low dry matter (DM, 160 g kg‐1), low water soluble carbohydrate (WSC, 15 g kg‐1), non‐additive treated silage with silage treated with commercial inoculants or formic acid with or without added formalin (formic acid ± formalin). Formic acid ± formalin significantly decreased silage pH and ammonia‐N and significantly increased silage residual WSC compared with inoculant or untreated silage. Formic acid ± formalin significantly increased oven DM and significantly reduced DM loss during ensiling compared with untreated silage. Formic acid ± formalin treatment significantly increased both silage DM and total DM intake compared with untreated silage. Daily liveweight gains of cattle offered formic acid ± formalin were significantly higher than those given inoculant or untreated silage.

It is suggested from the results that formic acid ± formalin additives can be used successfully to prevent a clostridial fermentation developing when crops contain 15 g WSC kg‐1.
Grazing effects on shoot and root dynamics and above‐ and below‐ground non‐structural carbohydrate in Caucasian bluestem
Authors: CHRISTIANSEN S , SVEJCAR T.
Published: April 2006

The objective of this study was to characterize changes in morphology and shoot/root total nonstructural carbohydrate (TNC) relationships in Caucasian bluestem (Bothriochloa caucasica) under grazing. Pastures were continuously grazed by steers weighing about 225 kg from mid‐May to late September of 1983 and 1984. Heavily grazed (H) swards produced more tillers m−1 than lightly grazed (L) swards. Number of tillers declined in both treatments during the midsummer drought period; however, the reduction was much less in H than in L swards. Above normal precipitation in August 1983 allowed number of tillers to rapidly recover (by approximately 4000 and 8000 m−1 for L and H treatments, respectively) reaching 10 700 and 17 800 tillers m−1 respectively, in late September. After 2 years of grazing, H swards initiated twice as many roots on an area basis; however, ability to penetrate soil to lower depths may have been reduced. Heavily grazed Caucasian bluestem had lower concentrations of total non‐structural carbohydrate (TNC) in shoots (P < 0.04) in both years, but had higher (28% at the end of 1984) TNC concentration in roots compared to lightly grazed (P= 001) plants. Greater root mass was found in lightly grazed swards; therefore, we suggest that root growth and TNC concentration tend to be inversely related. Total amount of TNC was higher in L swards, but during the course of the study total above and below‐ground TNC in H swards remained stable. Total above‐ground TNC pools are subject to short‐term variation and dilution from senescent herbage, thus TNC pools in individual plant parts may be a better indication of plant response.
Effects of fertilizer application to grasslands in Greece
Authors: PAPANASTASIS V. P. , KOUKOULAKIS P. H.
Published: April 2006

Grasslands in Greece are composed of a large variety of plant species, but they have relatively low productivity due to their misuse by domestic animals for thousands of years, and also to soil and climatic factors. Fertilizer application can improve productivity by affecting herbage yield, botanical composition, earliness of spring growth and quality. The application of N and P generally alters species composition and increases dry matter and crude protein yields, while the addition of K is often not effective. Also, NP fertilizer increases the in vitro digestibility while N often decreases P, Ca, Mg and Zn contents of herbage. It appears that Greek grasslands cannot utilize as much N as their temperate counterparts and that their soils are usually deficient in P. This indicates that NP fertilizer is necessary to secure increased yields with P being important in achieving a balanced grass‐legume composition in the plant cover.
1986 survey of upland grassland in England and Wales: changes in age structure and botanical composition since 1970–72 in relation to grassland management and physical features
Authors: HOPKINS A. , WAINWRIGHT JOANNE , MURRAY P. J. , BOWLING P. J. , WEBB MORAG
Published: April 2006

A sample of 10000 ha of grassland in seven upland districts originally surveyed in 1970–72 was re‐surveyed in 1986. Forty percent of the area was above 240 m elevation, 38% had gradients above 81/2°, 29% had poor or bad drainage and 54% was classified as having difficult or severe limitations to management. Twelve percent had been reseeded within the previous 5 years and 39% within 20 years; 6% was classified as arable grassland (in rotation with crops). Thirty‐four percent was usually mown, two‐thirds of it for silage. In most years 72% of grassland received fertilizer N (average application 123 kg N ha−1) and 35% received organic manure; nearly 20% received neither. Older swards tended to receive lower rates of fertilizer N than reseeds, hay fields and grazed fields less than silage fields, and fields on beef/sheep farms less than those on dairy farms. The proportion of sown species in swards averaged 35%, of which Lolium perenne accounted for 23%. A good contribution of Trifolium repens was recorded in 15% of the grassland. Herb species were recorded in 30% of the grassland, mostly in situations with low fertilizer N under hay or grazing. Agrostis spp., Poa spp., Holcus lanatus and Festuca rubra were the main unsown grasses. The average contribution of L. perenne had increased since 1970–72; it was also present in two‐thirds of the area from which it was absent in 1970–72, whilst the contribution of T. repens had decreased. The incidence of Cirsium arvense and Ranunculus spp. had also decreased, whilst that of Pteridium aquilinum had increased.
The utilization of N fertilizer, applied to perennial ryegrass/white clover pasture growing on a humus iron podzol in N.E. Scotland
Authors: RANGELEY ANNE
Published: April 2006

Applications of N fertilizer (0.40, 80, 120 and 240 kg N ha−1 year−1 in dressings of 40 or 80 kg N ha−1) were made to a perennial ryegrass/white clover (Lolium perenne L. Trifolium repens L.) pasture growing on a humus iron podzol reclaimed from heather (Calluna vulgaris L.) moor in 1982 and 1983. Where no N was applied, estimates of Ni fixation and mineralization were almost equal, being approximately 50 kg N ha−1 year−1 from each source. Apparent efficiencies of fertilizer use were generally low; for each dressing they ranged between –0·7 and 25·5 kg dry matter (DM)kgN−1. Also, responses to N fertilizer were affected by previous dressings. The net N recovery in harvested herbage from application of 120 kg N ha−1 year−1 was 30 kg N ha−1 year−1.
Photosynthetic potential of ryegrass pastures when released from continuous stocking management
Authors: KING J. , SIM E. M. , BARTHRAM G. T. , GRANT S. A. , TORVELL L.
Published: April 2006

The relationship between the rate of canopy gross photosynthesis and LAI was investigated for ryegrass swards released from grazing after a period of continuous stocking to maintain the pasture at LAI 2–3. The regrowing swards were allowed to increase to about LAI 5 over a period of about 2 weeks while the rate of photosynthesis was measured and compared with that for continuously stocked swards maintained at LAI values between 2 and 6. Gross photosynthesis was found to increase more rapidly than LAI on the regrowing swards than on the steady‐state control pastures. However, this response appeared to be influenced by seasonal factors. The potential increase in net COi uptake was estimated to range from 0 to 22%. The response was attributed to an increasing proportion of young photosynthetically‐efficient leaves near the top of the canopy, modified by seasonal changes in the rate of tillering. The agronomic implications of the results are iscussed.
Seasonal variation in white clover content and nitrogen fixing (acetylene reducing) activity in a cut upland sward
Authors: MARRIOTT C. A.
Published: April 2006

The seasonal variation in herbage mass and nitrogen fixing (acetylene reducing) activity of white clover in an upland sward, cut weekly to 3·5 cm from mid‐May until mid‐October, was measured. Acetylene reducing activity (ARA) was measured over a 24‐h period at 3‐weekiy intervals starting on 3 March 1983. Clover leaf and Stalon biomass was measured by harvest of the assay truces, and from mid‐May quadrat euts to 3·5 cm above the soil surface provided estimates of herbage accumulation.

Little A RA was detected in March, but activity increased substantially after 10 cm soil temperatures reached > 3°C, and peak activity per unit of clover leaf dry weight occurred in June and July; standing clover leaf dry matter increased during the season to a maximum of 60·5 g m−1 in June. Acetylene reducing activity was positively correlated with the number of rooted nodes, and Stalon and leaf dry weights in early spring. Thereafter, except during a period of summer drought, ARA was positively correlated with the amount of clover leaf material.

Clover population density increased during the season and maximum growing point numbers (5540 m−1) occurred in September; maximum leaf number per unit area (12 984 m−1) was found in October, prior to the final cutting of the site.

Results suggest that higher levels of nitrogen fixation in upland swards should be obtained if sward management regimes, which encourage a high clover leaf area, are adopted.
Digestibility of energy and gross energy intake in fresh pastures
Authors: OSORO K. , CEBRIAN MERCEDES
Published: April 2006

Several experiments were performed in spring summer over the period 1982–85 to study the relationships between digestibility of energy (DE), gross energy intake (GEI), acid detergent fibre (ADF) and dry matter (DM) content in pasture.

Wether sheep in metabolism pens and fed ad libitum with daily‐cut fresh pasture were used. Two plots with different botanical composition were used to provide herbage; one dominated by Lolium perenne and the other by Holcus lanatus. A high correlation (r= ‐0·91) was observed between DE and ADF. The prediction used a second‐order degree polynomial.

Gross energy intake and digestibility of energy were scarcely correlated (r= 0·50) when all cases as a whole were considered. Higher correlations between GEI and DE (r= 0·69) were obtained when only data from pastures where Holcus lanatus prevailed were considered, and still higher (r= 0·91) in those pastures dominated by sown species with DE values lower than 70%.

Herbage DM content had a large effect on GEI(r= 0·83) in the pastures dominated by perennial ryegrass with DE higher than 70%, the correlation between DE and GEI being low and negative (r=‐0·36). It is possible, therefore, to predict apparent digestibility of pasture energy from ADF. However, DE is closely related to GEI only in those pastures in which DE is lower than 70%, DM content being an important factor limiting the intake of those fresh pastures dominated by Perennial ryegrass when DE is above 70%.
The suitability of plant tissue tests to indicate phosphorus deficiency in perennial ryegrass (Lolium perenne L.)
Authors: RANGELEY ANNE
Published: April 2006

The phosphorus (P) status of perennial ryegrass was measured using three tissue tests. The results were compared with dry matter (DM) production from ryegrass, and levels of extractable soil P, taken from a fertilized non‐calcareous gley in a field experiment. Large errors were associated with the test values but it was possible to separate P deficiency from luxury uptake with tissue tests for total P and inorganic P (Pi) in leaves. The latter test is simple and merits further investigation.
Variation in HCN potential among cultivars of white clover (Trifolium repens)
Authors: WHEELER J. L. , VICKERY P. J.
Published: April 2006

The hydrogen cyanide potential (HCNp) of 17 cultivars of white clover were compared. With inadequate phosphorus supply, HCNp ranged from 24 mg kg DM−1 for cv Lucky to approximately 640 mg kg DM−1 for cv Huia and from 6 to 322 mg kg DM−1 for the same cultivars, with adequate phosphorus. The four North American cultivars examined had notably lower HCNp than all European or Australasian cultivars except cv Clarence.
An evaluation through lactating cattle of a bacterial inoculant as an additive for grass silage
Authors: GORDON F. J.
Published: April 2006

Three silages were prepared from herbage treated with either an inoculant (Ecosyl, Imperial Chemical Industries plc) at 3.21 t−1, formic acid (850 g kg−1, Add F BP Chemicals International Ltd) at 2·3 1 t−1, or no additive (control). The herbage used was the first regrowth from perennial ryegrass swards. It was ensiled unwilted, and had mean dry matter and water soluble carbohydrate concentrations at ensiling of 154 and 24·1 g kg−1 respectively. Time course studies showed only minor effects of additive treatment on fermentation patterns within the silo and all three silages had good fermentations. Over an 88 d feeding period, commencing on day 7 of lactation, forty‐eight British Friesian cows were used to evaluate the silages in a three‐treatment, 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 196 g kg−1 crude protein. On the basis of the data recorded during the final 28 d on treatment the animals receiving the inoculant‐treated silage consumed 12 and 10% more silage dry matter and produced 2·1 and 2·3 kg d−1 more milk than those given the control and formic acid‐treated silages respectively. Over the total experimental period the milk yields were 1957, 1894 and 2094 (±41·3) kg for animals receiving the control, formic acid‐ and inoculant‐treated silages respectively. Animals offered the formic acid treated silage produced milk of significantly higher fat concentration than those given the other two silages. Total ration digestibility studies, conducted with three cows per treatment, indicated no significant differences in digestibility coefficients, nitrogen utilization or metabolizable energy concentrations of the three treatment diets. It is concluded that the higher milk yield recorded with the inoculant‐treated silage, and the higher milk fat concentration with the formic acid‐treated silage, over that obtained with the control silage, were due to the increases in ME intake of 5 and 16 MJ d−1 for the formic acid and inoculant‐treated silages respectively.
Effect of seed crop management on potential seed yield of contrasting white clover varieties
Authors: HOLLINGTON P. A. , MARSHALL A. H. , HIDES D. H.
Published: April 2006

An experiment is described in which the effects of different spring managements on the potential seed yield and seed yield components of three white clover cultivars of contrasting leaf types were assessed. Cv. S184, the small‐leaved variety, produced more but smaller inflorescences than CVS Olwen, a large‐leaved variety, or Menna, a medium‐leaved variety. However, cv. Olwen, produced inflorescences with more florets, seeds per inflorescence and a higher seed yield per ten inflorescences than the other cultivars. Both potential seed yield and the individual yield components were influenced by management. Cv. Olwen produced more inflorescences and a higher potential seed yield under a cutting system than under grazing systems, which reduced the number and size of the inflorescences. Cvs S184 and Menna were less influenced by management system and performed similarly under cutting and grazing. The highly significant relationship between the number of ripe inflorescences and potential seed yield showed clearly that high seed yields are only achieved if the crop is harvested when the number of ripe inflorescences is at a maximum. The relatively short duration of the period of maximum ripe inflorescences emphasized the importance of determining the correct harvesting date, although weather conditions also play an important part in deciding when to harvest. Florets per inflorescence, seed set and 1000 seed weight remained relatively constant over the harvest period, and were not influenced by harvest date. The results are discussed in relation to the management of white clover seed crops and the importance of climatic conditions during seed production.
Turnover of grass laminae and white clover leaves in mixed swards continuously grazed with steers at a high‐and low‐N fertilizer level
Authors: LAIDLAW A. S. , STEEN R. W. J.
Published: April 2006

Turnover rates of grass laminae and clover leaf tissue were estimated over a range of intervals within three periods each year in the second to fourth years (1983‐85) of a trial involving swards continuously grazed by steers and receiving either 60 kg N ha‐1 in spring (60N) or 360 kg N ha−1 throughout the year (360N). Within the 60N swards initial stocking rates at turnout were low (60N LS) at 7‐2 steers ha−1 and high (60N HS) at 90 steers ha−1 in 1983, and in 1984 and 1985 corresponding rates were 10‐8 and 13‐5 ha−1. The 360N swards were initially stocked at turnout at 96 (360N LS) and 120 (360N HS) steers ha−1. Stocking rates were reduced by 33% in midsummer except for 60N in 1984 and 1985 when they were reduced by 50%.

Meaned over 3 years, 360N HS had lower herbage mass than 60N LS. Tiller density in 360N was almost 50% higher than in 60N and clover growing point density was only one quarter that of 60N with the 60N LS having lower clover densities than 60N HS in 1985.

Generally, leaf extension rate per tiller was higher in 360N than 60N and, when significant, 60N LS had higher senescence rates per tiller than 360N HS.

Rate of increase in new clover lamina tissue per stolon was not affected by treatments, whereas in 1983 LS had higher senescence rates of clover laminae than HS. Petiole growth per stolon was higher in LS than HS in 1983 and 1984, the mean over these years for 360N HS being 77% that of 60N LS. Petiole senescence per stolon was lower in 360N HS than 60N LS only in 1983.

When comparing 60N HS and 360N LS (representing similar levels of grazing intensity, having similar herbage mass) the gross growth of leaf material in the former was 75% of the latter, in contrast to 57% for net growth. Clover contributed 18% to the estimated growth of leaves compared to a mean of 7% in herbage mass. Taking inflorescence and pseudostem into account in 1984 and 1985,60N HS had 7% clover in standing herbage and 14% in net growth. Therefore, the contribution of clover to growth is considerably higher than its presence in herbage mass would suggest in continuously grazed swards. It is concluded that low‐N swards, owing to their lower tiller density and slower grass leaf extension rate, will be less efficiently grazed than swards at higher N levels at a given herbage mass, but the presence of clover will partly offset that disadvantage.
Effects of sward surface height on the performance of continuously stocked spring‐calving beef cows and their calves
Authors: WRIGHTand I. A. , WHYTE T. K.
Published: April 2006

The response of continuously stocked spring‐calving beef cows and calves to a range of sward surface heights was determined. Mean sward heights of 4‐5, 60, 70, 91 and 11‐0 cm (treatments A to E respectively) were maintained from mid‐May to mid‐August (Period 1) and treatments C, D and E continued until the end of September (Period 2), during which time mean sward heights were 5‐4, 7‐8 and 9‐2 cm respectively. Hereford x Friesian or White Shorthorn‐x Galloway cows with their Charolais‐cross calves were used, with 9, 6, 6, 5 and 9 cows on treatments A to E respectively. During Period 1 the mean live weight gains of cows were‐0‐52,‐005,0‐32,075 and 0 40 (s.e.d. 0167) kg d−1 on treatments A to E respectively and during Period 2.‐0‐31, 057 and 059 (s.e.d. 0153) kg d−1 for treatments C, D and E respectively with maximum cow liveweight gain at sward heights of 8 to 10 cm. Calf liveweight gains were 0 88,091, 098, 1 04 and 1‐06 (s.e.d. 0068) kg d−1 in Period 1 for treatments A to E respectively and 098, 1‐22 and 1 35 (s.e.d. 0067) kg d−1 in Period 2 for treatments C, D and E. The percentage of area infrequently grazed was generally less than 20% on treatments A to D, but on treatment E it was more than 40% for 6 weeks after turnout and thereafter remained between 20 and 40%. Maximum calf liveweight gain per hectare was achieved on the shorter swards, but maximum total liveweight gain of cows and calves per hectare occurred on treatment D. It is concluded that for maximum cow and calf performance on continuously stocked pastures, sward height should be maintained at no more than 8 cm in spring and early summer and then increased to 9 to 10 cm later in the grazing season.
The prediction of the in vivodigestibility of the diet of sheep and cattle grazing indigenous hill plant communities by in vitrodigestion, faecal nitrogen concentration or indigestible' acid‐detergent fibre
Authors: ARMSTRONG R. H. , COMMON T. G. , DAVIES G. J.
Published: April 2006

Herbage and faeces samples were retained from an intake and in vivodigestibility trial using material harvested at three different stages from five indigenous hill plant communities (those dominated by Agrostis‐Festuca., Nardus stricta., Molinia caerulea., Eriophorum vaginatum and Tri‐chophorum caespitosum) and from sown swards of ryegrass or white clover. Samples of the herbages and of their separate components, together with extrusa samples of the same herbages recovered from pen‐fed sheep and cattle oesophageal fistulates, were digested in vitrousing rumen liquor. Measurements were made also of faecal nitrogen concentration (FN) and of indigestible acid‐detergent fibre (IADF) using the samples from the original trial.

The range of in vitrodisappearance values of the herbages (IVOMD; 0809‐0278) was slightly wider than those of in vivodigestibility (OMD; 0‐796‐0‐37I). Differences between OMD and IVOMD were greatest at low quality and relationships were best described by two separate linear regressions of OMD on IVOMD for (a) ryegrass, white clover, Agrostis‐Festucaand Nardus(RSD; 0 0185) and, (b) Molinia, Tricho‐phorumand Eriophorum(RSD; 00246). In vitrodisappearance values of extrusa were higher than those of herbages offered by 00503 and 00156 units for sheep and cattle respectively, partly because of greater levels of ensalivation, especially in the sheep. The relationships of OMD to IADF and to FN were poor, though inclusion of faeces output and fitting parallel lines for communities in the regression of OMD on FN reduced the RSD to 0020. We conclude that in vitrodigestion of samples of extrusa, using appropriate standards, is the best method of diet digestibility prediction for sheep and cattle grazing these communities.
The impact of grazing severity on perennial ryegrass/white clover swards stocked continuously with beef cattle
Authors: GIBB M. J. , BAKER R. D. , SAYER ANNA M. E.
Published: April 2006

An experiment was carried out to examine the changes in perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) populations in mixed swards, under different grazing severities over three successive grazing seasons. In year 1, three paddocks were erected on a sward with a low initial content of clover (block 1). Sward heights were measured using a rising‐plate meter, and were maintained at overall mean heights of 3·0, 5·5 or 7·0 cm by variable stocking with 8‐month‐old steers. In year 2, a further three paddocks were erected on an adjacent area with a high initial content of clover (block 2), and were maintained at the same three heights by similar management. Botanical analyses were carded out on samples collected at four times during the season. Maintaining swards at 5·5 or 7·0 cm led to a large proportion of the area being infrequently grazed. Block I paddocks had higher initial tiller densities, which increased as sward height was reduced, while block 2 paddocks, with their lower initial tiller density, showed little effect of sward height on tiller density. Initially, clover stolon growing‐point densities and stolon masses increased more rapidly in the taller swards. Later, however, large losses in the clover populations occurred on all paddocks during long wet winters and there was a general reversal in these trends for stolon growing‐point densities and stolon masses, 3·0>5·5>7·0. By year 3, swards with differing
Ingestive behaviour of beef cattle offered different forms of lucerne (Medicago sativa L.)†
Authors: DOUGHERTY C. T. , BRADLEY N. W. , CORNELIUS P. L. , LAURIAULT L. M.
Published: April 2006

A change‐over design was used to establish the ingestive behaviour of twelve adult Angus cows (Bos taurus), live weight (LW) of 475 ± 18 kg, while grazing luceme (Medicago sativa L.) (T1), eating from a swath of freshly cut lucerne (T2), or eating wilted lucerne from a swath (T3). In the first experiment, the herbage dry matter (DM) allowance was 4‐7 kg h−1 and in T1 the available herbage DM mass (>5 cm) was 2892 kg ha−1. Herbage DM intake was 2.5, 1.6 and 2.0 kg h−1 (0.53,0.35 and 0.41 kg (100 kg LW)−1h−1) for T1, T2 and T3, respectively. Cattle grazed at 29 bites min−1 and ate the swathed lucerne at 6 bites min−1. Herbage DM intake per bite was 1‐2, 4‐9 and 6‐7 (2‐5,104 and 14‐4 mg(kg LW)−1)for T1, T2 and T3, respectively. The DM content of the luceme was 227, 263 and 309 g kg−1 for the same sequence. In a second experiment with luceme of available herbage DM mass of 5321 kg ha−1 and an allowance of 7‐ 3 kg h−1 cows grazed lucerne at 2‐9 kg h−1, ate freshly cut material at 21 kg h−1 and wilted herbage at 25 kg h−1 (0.61, 0.45 and 0.52 kg (100 kg LW)−1h−1), respectively. Leaf accounted for 80%, 68% and 54% of intake for T1, T2 and T3, respectively. Swathing lucerne reduced the diet selectivity by forcing cattle to take large bites that required many jaw movements to form a bolus that could be swallowed. It appeared that the mechanics of bolus formation determined ingestive behaviour of cattle eating swathed herbage.
Prevalence of Listeria species as related to chemical quality of farm‐ensiled grass
Authors: HUSU J. R. , SIVELÄ S. K. , RAURAMAA A. L.
Published: April 2006

The occurrence of Listeria spp. in pasture grass and grass silage made with various additives and preservation techniques is reported. Silage samples were collected three times (in November, February and May) from eighty dairy farms. The prevalence of Listeria spp. in pasture grass samples was 0.647 and in silage samples 0.227. Only two species, L. monocytogenes and L. innocua were observed. Listeria spp. Were isolated from the silage at least once at thirtynine farms (0.488), and L. monocytogenes at twenty‐seven farms (0.338). The occurrence of Listeria was highest among the silage samples collected in November (0.288). Silages preserved with acids had the lowest prevalence of Listeria (0.194). Silages preserved in tower silos were most often free of Listeria, only 0.056 being positive. The highest prevalence of the Listeria spp. (0.324) was detected in clamp silage. The results of chemical analyses of silage statistically reflect the frequency of Listeria.
Growth, colonization and productivity of two white clover cultivars strip‐seeded into an upland Festuca‐Agrostis sward
Authors: WILLIAMS E. D. , HAYES M. J.
Published: April 2006

Small plots of a Festuca‐Agrostis upland sward on a peaty gley podsol were strip‐seeded during late June 1986 with white clover cvs Aberystwyth S184 or Menna at 4 kg ha−1 and defoliated early (20 August) or late (3 September) and then frequently or infrequently (every 2 weeks or 4 weeks) until the end of September. All plots were defoliated in early November, at 3‐weekly intervals during the growing season in 1987 and then grazed rotationally during 1988.

Satisfactory seedling establishment, representing 46% emergence, was achieved 5 weeks after sowing. The differential defoliation regimes had no persistent significant effects on clover development. S184 soon produced more leaves per seedling than Menna and a smaller proportion of its leaf number and weight were removed at each defoliation. Following large losses of leaves over the 1986–87 winter, SI84 had significantly more leaves per stolon than Menna; subsequently it also colonized the sward at a quicker rate. During 1987 amounts of herbage harvested (6.1 t ha−1) were similar with the two clover cultivars, with S184 contributing 47% and Menna 44% of this respectively. SI84 made a larger contribution to yield during May and June but Menna was more productive during September and October. During 1988 clover populations were maintained with rotational grazing without additional fertilizer inputs.

The results show that, despite initial soil and climatic contraints, both small and medium‐leaved clovers can be strip‐seeded into upland swards with large subsequent benefits to yield and herbage quality. However, they also indicate the need for further experiments to determine the influence of sward morphology and defoliation regime on stolon branching rates and accumulation of growing points which, in turn, govern sward colonization.
Productivity of prairie grass (Bromus willdenowii Kunth) affected by sowing date and the head smut fungus (Ustilago bullata Berk.)
Authors: FALLOON R. E. , ROLSTON M. P.
Published: April 2006

Effects of sowing date, fungicide seed treatments, and the head smut fungus Ustilago bullata Berk, on establishment, herbage, and seed production of prairie grass cv. Grasslands Matua (Bromus willdenowii Kunth) were measured in autumn‐ and spring‐sown field trials in New Zealand.

Autumn seedling establishment from thiram‐treated seed relative to untreated seed was increased by 27% from the earliest sowing (early March), and by 65% from the latest sowing 8 weeks later. Infestation of seed with ustilospores of U. bullata reduced seedling establishment at all but the latest autumn sowing. Fungicide seed treatments had little effect on spring seedling establishment, but V. bullata infestation of seed reduced establishment compared with healthy seed, particularly after late sowings (early November).

Herbage production was greater from early than from late sowings in both autumn and spring, and was less in plants grown from U. bullata infested seed than in plants from healthy seed. Enhanced autumn establishment from thiram‐treated seed led to improved herbage production when plants were young, but this effect disappeared about 18 weeks after late autumn sowing. Overall herbage production from spring sowing was more than twice that from autumn sowing.

A 6‐week delay in autumn sowing led to a 58% reduction in seed production the following summer.

Early autumn and spring sowings, together with adequate control of seedling diseases, are likely to give optimum herbage and seed production from prairie grass.
Short‐term effects of nitrogen on the growth and nitrogen nutrition of small swards of white clover and perennial ryegrass in spring
Authors: DAVIDSON I. A. , AFRC M. J. ROBSON
Published: April 2006

Small swards of white clover and perennial ryegrass were established in Perlite in a heated glasshouse, as either monocultures or mixtures of equal plant numbers. On 26th March, 1984 the swards were moved outside and their growth studied over the period to 29th May. All swards received a basal level of nitrate N to simulate soil mineralization and two‐thirds received additionally the equivalent of 80 kg N ha−1. Over the experimental period (26th March‐29th May) clover maintained its proportion of total mixture dry weight In swards given ‘fertilizer’‐N and increased its proportion in those given only ‘basal’ N, However, clover declined as a percentage of total mixture dry weight during the first period of the experiment when total leaf area index (LAI) and ambient temperatures were low, and increased its percentage later when temperature and LAI had risen. Changes in tiller and stolon growing point numbers were not good indicators of changes in dry weight. Relative yields and relative replacement rates also were not good indicators of relative performance in mixture. Where ‘fertilizer’‐N was applied, clover derived less of its nitrogen from that source than grass although their uptakes per unit shoot dry weight were similar.
Effect of fertilizer nitrogen source and cattle slurry on herbage production and nitrogen utilization
Authors: LONG F. N. J. , GRACEY H. L
Published: April 2006

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.
Effects of an established sward of Lolium perenne L. on the growth and development of Rumex obtusifolius L. seedlings
Authors: JEANGROS B. , NÖSBERGER J.
Published: April 2006

Seedlings of Rumex obtusifolius L. were grown in gaps (11 cm diameter) in an established sward at Lolium perenne L., Root competition from the surrounding sward was controlled by PVC tubes and shoot competition was controlled by cutting the sward frequently. All combinations, with and without root competition and with and without shoot competition, were used.

Plants received either 40 or 80 kg N ha−1 month−1 and 0 or 300 kg K2O ha−1 and were harvested 39 d after emergence; a second harvest was made 12 d later, after shading to 20% of full sunlight.

The shoot dry weight per plant of R. obtusifolius was much more affected by root competition than by shoot competition, especially at low nitrogen applications. Potassium supply had no effect.

More dry matter was allocated to the leaf petioles under shaded conditions and the specific leaf area was greater. This morphological plasticity enabled R. obtusifolius to grow well under shading and to be affected only slightly by shoot competition from L. perenne.

The results suggest that competition for nitrogen was the main factor limiting the initial grown of R. obtusifolius in a ryegrass sward and that the morphological characteristics of R. obtusifolius make it less susceptible to competition for light in the early stages of its development.
White clover seed production from mixed swards: effect of sheep grazing on stolon density and on seed yield components of two contrasting white clover varieties
Authors: MARSHALL A. , HIDES D. H.
Published: April 2006

A trial was carried out over two harvest years to assess the effect of sheep grazing and closing date on stolon density and seed yield components of two contrasting white clover varieties and to determine the potential for producing clover seed from mixed swards in an integrated livestock/seed production system.

Overall, the small‐leaved cv. S184 had a higher stolon density at closing and harvest than the large‐leaved cv. Olwen, but only significantly so in 1987. Stolon density at closing was generally increased by delaying closing. Varieties also differed in their response to closing date. Stolon density of cv. S184 in both harvest years, generally increased with later closing whilst cv. Olwen was less influenced by closing date and at all dates in 1987, and all but one date in 1986 was not significantly different from the ungrazed treatment.

Delay of closing significantly increased stolon density at harvest on all closing dates in 1987 but had no effect in 1986. Varieties responded similarly to a delay in closing but the magnitude of increase of cv. Olwen was less than that of cv. S184.

The seed yield components of both cv. S184 and cv. Olwen were influenced by closing date, but the effect differed between years. Although there was some initial increase in inflorescence production, delaying closing after inflorescence buds appeared on the stolon reduced inflorescence number of cv. Olwen in both years but reduced inflorescence number in cv. S184 in 1986 only. However, inflorescence size, seed yield per inflorescence and the proportion of ripe inflorescences at harvest was reduced in both years. Cultivar S184 produced more inflorescences than cv. Olwen in both years and in both years tolerated later closing than cv. Olwen.

The effect of sheep grazing and closing date is discussed in relation to stolon removal and the suitability of particular leaf types for this system of seed production.
Herbage productivity of a range of grass species in association with white clover
Authors: FRAME J.
Published: April 2006

Red fescue (Festuca rubra L.) cvs Reptans, Dawson and Ruby, perennial ryegrass (Lolium perenne L.) cvs Perma and Sprinter, crested dogstail (Cynosurus cristatus L.) cv. Southlands, smooth meadow‐grass (Poa pratensis L.) cvs Parade and Arena, Yorkshire fog (Holcus lanatus L.) commercial types I and II, creeping bent (Agrostis stolonifera L.) cv. Penncross and rough meadow‐grass (Poa trivialis L.) cvs Omega Øtofte, Dasas and Sabre were each sown with white clover (Trifolium repens L.) cv. Donna and the productivity of the fourteen mixtures assessed under simulated grazing (six harvests per year) for 3 years. A single fertilizer‐N rate (50 kg ha−1) in early spring was applied to all treatments each year.

Over the 3 years, mean annual dry matter (DM) production of the swards ranged from 5·25 t ha−1 (creeping bent) to 8·71 t ha−1 (red fescue cv. Reptans), with the species ranking order of: red fescue > perennial ryegrass > crested dogstail > smooth meadow‐grass > Yorkshire fog > creeping bent. Rough meadow‐grass only persisted over the first harvest year. Mean annual organic matter digestibility (OMD) values of the swards ranged from 0·712 (creeping bent) to 0·782 (ryegrass cv. Sprinter). Mixtures with the lowest proportion of grass (crested dogstail and smooth meadow‐grass) generally gave the highest proportions of white clover. The creeping bent mixture had exceptionally low production of both components.

Red fescue, crested dogstail and smooth meadow‐grass showed compatibility with clover and, therefore, have potential for use in grass/clover swards. Yorkshire fog had lower compatability with clover. Some breeding effort to improve selected characteristics of promising species, e.g. improvement of low OMD in red fescue, seems warranted.