bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilization of silage nitrogen in sheep and cows: amino acid composition of duodenal digesta and rumen microbes
Authors: CHAMBERLAIN D. G. , THOMAS P. C. , QUIG JAN 
Published: April 2006

AbstractTwo experiments are reported. In the first experiment the amino acid compositions of rumen bacteria and protozoa isolated from sheep given a diet of grass silage were compared with those taken from sheep given a diet of hay and barley; four sheep were assigned to each diet. There were no significant differences (P<0·05) between diets in the amino acid compositions of the microbial fractions and bacterial contents of α‐ɛ‐diaminopimelic acid were also similar for both diets.In the second experiment the digestion of a grass silage and barley diet (65:35; 135 g CP (kg DM)‐1) was studied using four non‐lactating Ayrshire cows fitted with cannulae in the rumen and in the proximal duodenum. The mean N intake was 154 g d‐1 and the corresponding duodenal flow was 126 ± 10 g d‐1 indicating that 0·21±0·07 of the N intake was absorbed between the mouth and the duodenum. The mean rumen NH3‐N concentration was high, 297 g litre‐1, and the mean rate of microbial protein synthesis in the rumen was low, 17 g microbial N (kg OM apparently digested in the rumen)‐1. There was a low content of bacterial N in the non‐ammonia N at the duodenum (mean proportion 0·52±005) and low concentrations of methionine and lysine in the duodenal digesta protein. The results are discussed in relation to previously published data on the digestion of silage diets in sheep and to the utilization of silage diets for milk production in the cow.It is concluded that with silage diets the supply of methionine and lysine to the duodenum is likely to be low because of the low rates of microbial protein synthesis in the rumen and that in cows those two amino acids may be limiting for milk production.
Some effect fluid‐sowing, pre‐germination, irrigation and soil covering on the establishment and growth of seedlings of white clover slot‐seeded into permanent pasture
Authors: HAYES M. J. , WILLIAMS E. D. 
Published: April 2006

AbstractSeeds of white clover (Trifolium repens) were sown alone or in fluid, or pre‐germinated in fluid on to the soil surface of slots cut in an old Agrostis/Festuca sward. Seeds were left uncovered or covered with a thin layer of soil and irrigated from the outset or after 14 days delay.With irrigation from the outset, seedlings established soonest from pre‐germinated seeds but final percentage establishment ranged only from 50 to 63% for the three states of seed. With delayed Irrigation, however, few pre‐germinated s1 survived and although germination of dry seed was delayed, final percentage establishment was unaffected. Soil covering increased establishment slightly. The number of leaves per seedling was greatest with pre‐germination and early irrigation and least with pre‐germination and delayed irrigation. Delayed irrigation also decreased the number of leaves per seedling for seedlings grown from dry seed.The effects of early irrigation persisted so that at 84 days it significantly increased total yield of clover from all three states of seed, on average threefold, but much more from pre‐germinated than from dry seed. Soil covering greatly increased yield, especially where irrigation had been applied from the outset. The interaction of early irrigation and soil covering was even more pronounced for stolon weights, and stolon growth of Individual seedlings appeared to benefit more from soil covering than from early irrigation.The results showed the importance of early seedling emergence, but no advantages of fluid sowing per se. They also indicated large overall beneficial effects of early irrigation and its additive interaction with soil covering.
A comparison of spectral reflectance and sward surface height measurements to estimate herbage mass and leaf area index in continuously stocked ryegrass pastures
Authors: KING J. , SIM E. M. , BARTHRAM G.T. 
Published: April 2006

AbstractMeasurements of sward surface height and of the ratio of light at 660 and 730 nm reflected from a pasture canopy were correlated with measurements of leaf area index (LAI) and herbage mass of two ryegrass dominant swards. Both pastures were continuously stocked by sheep to maintain a range of sward heights from 2 to 6 cm corresponding approximately to LAI 2 to 5.Sward height appeared to be linearly related to both LAI and herbage mass, whereas 660/730 reflectance displayed a non‐linear relationship with both parameters. The accuracy of prediction by the two methods over the range LAI 1 to 3 or herbage mass 700 to 1800 kg DM ha‐1 was very similar. However, reflectance measurements could not be used above about LAI 3–4 and to this extent were less useful. Nevertheless, reflectance measurements have a potential advantage in their ability to sample large areas of pasture very quickly.
Influence of long photoperiods on the growth of timothy (Phleum pratense L.) varieties from different latitudes in northern Europe
Authors: HAY R. K. M. , PEDERSEN K. 
Published: April 2006

AbstractPlants of three varieties of Phleum pratense L. from different latitudes (cv. Engmo, 69°N; cv. S48, 52°N; cv. Motim, 52°N) were grown from the five‐leaf stage at 12°C under continuous illumination or 8‐h days at essentially identical daily inputs of radiant energy. The responses to daylength extension (increase in plant dry weight, plant height and leaf dimensions and reduction in the number of tillers per plant and in tissue dry matter content) were common to all three varieties and although the enhancement in plant dry weight and in leaf size was greater in the Engmo plants, this was principally the result of poorer growth and smaller leaf size in 8‐h days. Marked differences between Engmo and the other varieties in the partitioning of dry matter within the plant were the consequence of differences in the rate of reproductive development. For example, compared with S48 and Motim, first spike emergence and 50% anthesis in the Engmo plants were delayed by 22 and 14 days, respectively, and 40% of the Engmo plants did not become reproductive even after 110 days of long‐day treatment. Furthermore, by the time that 50% anthesis of the mainstem spike had been reached by the long‐day plants of each variety, significant differences in tiller numbers and tiller fertility had developed between the varieties from high and lower latitudes. These findings and the results of previous studies of Poa pratensis, Dactylis glomerata and Bromus inermis are discussed in relation to the adaptation of high‐latitude grasses to the Scandinavian environment.
The effect of strategic fertilizer nitrogen and date of primary harvest on the productivity of a perennial ryegrass/white clover sward
Authors: FRAME J. 
Published: April 2006

AbstractFour management systems involving different dates for first harvest (simulated grazing, early silage, late silage and hay) and two fertilizer N rates in spring (0 and 80 kg ha‐1) were imposed on a perennial ryegrass cv. Talbot/white clover cv. Blanca sward during 1981‐82. In each year, annual total herbage DM was increased by spring application of N but white clover production and content in the total herbage were reduced; however, white clover, which was depressed in the harvests immediately after N application, recovered during the season to amounts and contents in the total herbage similar to those given no spring N.Annual total herbage DM production increased as the date of primary harvest was delayed (935 to 1197 t ha‐1 over two years) but mean organic matter digestibility values for the same period decreased (0‐769 to 0700). First‐harvest production made up substantial proportions of the annual production in the conservation systems. White clover, as shown by its production and the amount of stolon present, was tolerant of conservation systems, especially with no applied N.It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. The use of strategic spring N seems a viable option, but more knowledge of rates would be valuable since this experiment only compared 80 kg ha‐1 with no applied N.
Effect of fertilizer nitrogen on six‐year‐old red clover/perennial grass swards
Authors: McBRATNEY JUNE M. 
Published: April 2006

AbstractThree diploid red clover cultivars—Sabtoron, Violetta and Essex—and three tetraploid, Hungaropoly, Teroba and Red Head, were sown separately in pure culture and with each of three companion grasses: timothy (Aberystwyth S48), tall fescue (Aberystwyth S170) and perennial ryegrass (Aberystwyth S24).The effects of fertilizer N on yield and on clover/grass ratio over a 2‐year period (seventh and eighth harvest years) subsequent to 6 harvest years during which no N fertilizer was applied were investigated. The data for productivity and persistence have already been published (McBratney, 1981; 1984).Application of fertilizer N increased DM yields in the eighth year. In this year, the highest yield, 11·9t ha‐1, averaged over the six clover cultivars, was given in association with tall fescue. Tall fescue contributed 90% of this yield. Clover content continued to decrease in all swards but the decrease was greatest in the swards receiving fertilizer N. The yield of clover DM averaged over the six cultivars under N treatment declined from 5·6t ha‐1 in the seventh year to only 0·4t ha‐1 in the eighth year.The results from this trial demonstrate the potential of red clover sown either pure or in mixture with a suitable perennial grass, to maintain high output of quality herbage over a 6‐year period without the aid of fertilizer N. They further demonstrate that following decline in red clover content, both herbage yield and quality may be restored by the application of N fertilizer, particularly where the clover was seeded with a highly productive companion grass.
Microscopic and chemical changes during the first 22 days in Italian ryegrass and cocksfoot silages made in laboratory silos
Authors: WINTERS ANA L. , WHITTAKER P. A. , WILSON R. K. 
Published: April 2006

AbstractAlthough many aspects of grass silage have received intensive study, the changes that take place within the grass blades during ensilage have received little attention.In two factorial experiments Italian ryegrass (cv. Lemtal) and cocksfoot (indigenous) were ensiled in laboratory silos (capacity 0·2 kg) with the grass under pressure (700 Pa) and subjected to two treatments (with or without 3·31 t‐1 85% formic acid) and two silos from each treatment opened on eight sampling dates(1,2,3,4,7,10,14 and 21 d).For each sampling date transverse sections of grass laminae were examined and changes in the cross sections of the protoplasts and of cells, as defined by the cell walls, were recorded. These data were used to calculate the ratios of protoplast to cell volumes at each sampling date.Each silage was analysed for dry matter, pH, lactic acid, VFA, ammonia and glucose. The distance settled by the silage (a measure of decrease in silage volume) and the silage conductivity were also recorded.Both of the untreated grasses yielded silages with typical lactic acid levels and pH values. In all of the silages there was a marked shrinkage of the plast within the space defined by the cell wall. The ratio of protoplast to cell volume eventually stabilized at 0·4. The formic acid‐treated grasses reached this level by day 1 but a longer period was required by untreated grasses.It is suggested that the decrease in silage volume is related to the lactic acid content of the liquid phase due to their close relationship in silages produced from untreated grasses (r= 0·97***).
Comparative sheep production and herbage characteristics on four perennial ryegrass varieties in the uplands
Authors: DAVIES D. A. 
Published: April 2006

AbstractEwe and lamb performance, herbage production and feed quality components on four late‐flowering perennial ryegrass (Lolium perenne L.) varieties were assessed under a fixed stocking management at an upland site (305 m OD) in mid‐Wales. Averaged over four years (1981–84) there was no significant difference (P>0·05) between Aberystwyth S23, Aberystwyth Ajax, Perma and Meltra (tetraploid) in ewe and iamb liveweight gains. There were, however, considerable differences between varieties during individual years and their relative ranking also changed substantially over the four years. Lamb production on Perma was 22% more than on S23 in the first year but by the fourth year it was 21 % less than on the latter variety.Differences between varieties were observed in herbage production. Net herbage accumulation was 15% more on Meltra than on Ajax whilst the calculated quantity of OM consumed was 19% higher from Meltra than from both Ajax and S23. Net animal liveweight gains were positively correlated with herbage production (r = 0·95, P < 0·05) and DOM consumed (r=0·96. P<0·05).
Forage production and quality of several crop rotations and pastures in northwestern Spain
Authors: LLOVERAS‐VILAMANYA JAIME 
Published: April 2006

AbstractMultiple cropping has been used for many years to increase production in temperate areas of Europe where the growing season is favourable and is important when land area is limiting.The purpose of this 3‐year study was to determine how several different cropping systems affected forage production potential at three rainfed locations in northwestern Spain (Galicia). The cropping systems compared were: single crop maize; double crop systems of maize‐rye, maize oats+ vetch, and maize‐Italian ryegrass; three crops in a two‐year rotation of maize‐Italian ryegrass (12‐months) forage rape; 2‐year pasture maize and two contrasting 3‐year grass‐legume mixtures.There was an increase in dry matter (DM) production as cropping intensity increased. The one‐year double cropping systems always yielded more than three crops in two years, which in turn outyielded single crop maize or 3‐year pastures. The highest DM yields were 20–9 t ha‐1 from the maize‐oats‐I‐vetch rotation. Maize was the principal crop determining total production, yielding about 70% of the total DM for the double cropping systems. The maize component gave similar annual yields in the multiple crop and maize‐pasture rotations, but the use of maize allowed double cropping, which increased production compared with 3‐year pasture.Forage rape gave the highest in vitro dry matter digestibility (IVDMD) of 773–815 g kg‐1 while the oats‐I‐vetch mixture gave the highest crude protein (CP) concentration (105‐217 g kg‐1). The maize crops had the lowest CP content (62‐76 g kg‐1) though digestibility was high (653‐713 g kg‐1).
Studies on the estimation of sampling error for leatherjackets (Tipula spp.) in grassland
Authors: BLACKSHAW R. P. 
Published: April 2006

AbstractLeatherjacket populations were sampled from 20 sites in Northern Ireland by collecting 10 cm diameter soil cores and wet sieving. The sample variances were linearly related to the sample means. Up to a mean of 1.14 leatherjackets per core, populations could be described by the Poisson distribution. Negative binomial distributions could also be fitted to data where the sample variance was greater than the sample mean. A strong curvilinear relationship was found between the sample mean and the proportion of cores containing leatherjackets. The raw data were used to generate a series of equations which in turn gave rise to a function linking frequency, sample mean and sample size.The implications of these results are discussed in relation to population estimation and advice to farmers.
The effect of subsequent mangement on the success of introducing white clover to an existing sward
Authors: SHELDRICK R. D. , LAVENDER R. H. , PARKINSON ANN E. 
Published: April 2006

AbstractTwo experiments, each lasting approximately 12 months, were carried out at North Wyke, Devon, in 1982‐83 (A) and 1983‐84 (B), to investigate various sward managements following oversowing of white clover (Trifolium repens, cv. Grasslands Huia) at 4 kg ha‐1 with a Hunter Rotary Strip‐Seeder in June or July into the stubble of a permanent grass sward following conservation. Experimental managements comprised cutting, grazing with wether sheep or grass suppression by herbicide, as appropriate, in late summer/autumn (Phase I), winter (Phase II) and spring/early summer (Phase III).During Phase I, there was no differential effect on clover stolon development of lenient grazing at approximately 4‐weekly intervals or topping at the same frequency to a similar height. Early in Phase II of Experiment A, grazed paddocks became so badly poached that no differences occurred between grazing either to early January or throughout the winter. Under drier conditions in Phase II of Experiment B, continuous grazing at either five (L) or ten (H) sheep ha‐1 had no immediate effect on clover stolon development, but in a silage cut in June, paddocks formerly stocked at the lower rate yielded 40% more DM than those at the higher rate.Experiment A compared the use of a grass‐suppressing herbicide, propyzamide, applied at 0.6 kg a.i. ha‐1 in either October or February; in Experiment B it was applied in October. Prophyzamide applied at either time in Experiment A increased the clover content of herbage regrowing after the end of the experimental period from 16% to 36% (s.e.d. ± 3.9). In Experiment B, October application raised the clover contents of herbage cut in June 1984 from 10% (H) and 17% (L) to 32% (s.e.d.±5.9), and stolon lengths per m2 at the end of the summer period from 33 (H) and 56 (L) to 86m (s.e.d. ± 11.7). However, the effect of spraying propyzamide on subsequent herbage yields was erratic, and appeared to depend on the incidence of frost after application.In Phase III of Experiment A, continuous grazing was compared with a silage cut in June. At the end of the experiment there were 31 m m‐2 of clover stolon in silaged areas compared with only 2.5 m m‐2 following grazing (s.e.d.±6.6). Clover content and herbage yields were also significantly higher following conservation. In Experiment B in the same period, rotational grazing with a 14‐ or 35‐day recovery interval was compared with a silage cut in June, with or without 100 kg N ha‐1 applied in March. Application of N to the conservation treatment reduced clover stolon length per unit area, and in the regrowth in the post‐experimental period the conservation treatment without N had the largest clover content (31% compared with 16‐23% for other treatments, s.e.d. ± 3.6)
Tillering and leaf area index in grasses in the vegetative phase
Authors: SIMON J. C. , LEMAIRE G. 
Published: April 2006

AbstractThe relationship between tillering of a vegetative grass stand and Leaf Area Index (LAI) has been studied during sward establishment of perennial ryegrass and Italian ryegrass with different seedling densities and nitrogen fertilizer rates and on established swards of tall fescue during winter and early spring after different dates of last cut in autumn.The different experiments on different species led to the conclusion that in every instance the tillering rate slows down as soon as the LAI reaches a value of 3 and terminates rapidly at higher LAI, which corresponds with the almost complete extinction of light at the level of the tiller buds. The results confirm the direct role of light on morphogenesis previously demonstrated by several authors. The existence of such a limit of LAI helps to explain some contradictory effects of temperature or nitrogen on tillering.
Factors affecting the leaf extension rate of perennial ryegrass in spring
Authors: BAKER ANNE‐MARIE , YOUNGER A. 
Published: April 2006

AbstractThe effects of soil temperature and other factors on the early spring growth of perennial ryegrass (Lolium perenne) swards were studied in 1983, 1984 and 1985. Leaf extension was used as the measure of growth and soil temperature was recorded at 10 cm depth below bare ground. Measurements were taken before the first nitrogen dressing had been applied each spring on swards that had received annual dressings of 0, 200 or 400 kg N ha‐1 since 1982.On the pooled data temperature alone accounted for 604% of the variation in leaf extension rate, with an average increase of 0·4 mm d‐1 for each 1°C increase in temperature over the range studied. Considering the data for each year separately did not greatly improve the correlation but did indicate that leaves extended more rapidly in 1985 for each degree increase in temperature whereas the smallest response was recorded in 1984. A better correlation was achieved by grouping data according to the nitrogen rates previously applied to plots and there was evidence of residual effets of this nitrogen. It seems likely that the differences between years can be explained in terms of differences in radiation and other environmental parameters over the measurement period, whereas the effects of previously applied nitrogen may be more closely related to physiological changes in the sward.
The deposition of Caesium 137 on grassland at a site in SW England following the Chernobyl accident
Authors: GILBEY J. , BRADLEY S. , WALLING D. E. 
Published: April 2006

AbstractFollowing the Chernobyl accident in April 1986 137Cs was detected in samples of grass collected at AGRI, North Wyke, Devon, UK. Samples of grass from permanent and reseeded swards under uniform management were taken on three occasions. The 137Cs content of the samples was assessed as both Bq kg‐1 of sample and Bq m‐2, Samples taken from the same site in 1985 were used as a control group; these contained no measurable 137Cs. The samples taken on 8 May 1986 had a 137Cs content of approximately 30 Bq kg‐1; by 31 July 1986 the content had dropped to 1% of this value. The permanent pasture initially showed a higher level of 137Cs than the reseeded sward. Analysis of soil cores from the sampling area showed a much higher level of 137Cs than that found in the herbage. This was attributed to the atmospheric testing of nuclear devices in the early 1960s: the short‐lived 137Cs isotope was found in the 1986 herbage samples but not in the soil cores.
Variation in spring temperatures, grass production and response to nitrogen over twenty years in the uplands
Authors: DAVIES D. A. , MORGAN T. E. H. 
Published: April 2006

AbstractLarge between‐year variation was observed in spring air and soil temperatures at Pant‐y‐dwr Hill Centre (305 m altitude) from 1967 to 1984 and at Bronydd Mawr Research Centre (330 m) from 1985 to 1986 in Powys. The mean date of attaining T‐sum 200°C accumulated air temperature was 13 March (range 9 February to 23 April) and that of soil temperature at 100 mm depth permanently above 5 5°C was 9 April (range 7 March to 4 May). Net herbage accumulation and response to applied N from Aberystwyth S23 perennial ryegrass (Lolium perenne L.) swards during April were also highly variable and were correlated with the date of reaching target soil temperatures of above 5 5°C for 5 consecutive days (r=−0·68, P < 0·001 for net herbage accumulation and r=−0·70, P < 0·001 for response to N).The use of early flowering varieties of perennial ryegrass gave a significant increase of herbage growth in spring compared with late varieties. From 1979 to 1980 net herbage accumulation during April from the early variety Frances was 94% more than from Perma (late) and 55% more than from Talbot (intermediate) varieties. Under conservation management more winter hardy and persistent varieties of Italian and hybrid ryegrasses (L. multiflorum L. and L. multiflorum X L. perenne) gave higher quantities of firstcut silage crops in early June than RvP Italian ryegrass.After the severe winters of 1978–79 and 1985–86, subsequent spring production from a wide range of ryegrasses was shown to be affected by sward survival, highlighting the value of winter hardy varieties when resowing in the uplands