bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competition in perennial ryegrass–white clover mixtures under cutting. 2. Leaf characteristics, light interception and dry‐matter production during regrowth
Authors: Nassiri  , Elgersma  
Published: March 2003

The effect of defoliation interval on growth patterns of contrasting perennial ryegrass (Lolium perenne)–white clover (Trifolium repens) mixtures was studied. The dynamics of increase in leaf area, light interception and dry‐matter (DM) production were measured within successive regrowth periods. No N fertilizer was applied. During 1995 six mixtures were cut eight (F1) or six times (F2) at a stubble height of 5 cm. The stubble composition was stable throughout the growing season: after harvest about 50 g DM m−2 (with a white clover proportion of 0·52) was present with a leaf area index (LAI) of 0·5 (0·38 white clover). The percentage of intercepted radiation after cutting was 20–30% and increased during 3 weeks to about 95%.The relative growth rate of leaf area and DM was higher for white clover than for perennial ryegrass, with the proportion of clover in the LAI and DM increasing during each regrowth period. Mixtures with large‐leaved white clover cv. Alice had a lower initial clover content after harvest, but a more rapid increase in clover LAI and DM than mixtures with the smaller leaved cvs Gwenda or Retor. Alice had the highest total and clover LAI and DM at harvest. Cutting frequency affected the change in white clover–perennial ryegrass ratio during regrowth. This was significantly higher in mixtures with Alice than in mixtures with Gwenda, but only under less frequent cutting (F2).In spring there was a mean white clover proportion of about 0·55 in the LAI and 0·45 in the total harvested DM. In summer the white clover proportion in the LAI and DM increased to 0·70–0·75. There was a decline during autumn, especially in F2 and in the mixtures with the small‐leaved white clover cv. Gwenda and the medium‐leaved cv. Retor. In contrast, grass DM and LAI declined from spring to summer. The decline in clover LAI in autumn was similar in Alice and Gwenda at frequent cutting (F1), but stronger in Gwenda in F2. Retor had the lowest clover specific leaf area (SLA). The SLA values of Alice and Gwenda were similar, SLA being similar between cutting treatments. No differences were found for leaf weight ratio (LWR) among the three white clover cultivars or between the grass cultivars, and LWR was not affected by cutting treatment. Defoliation interval had limited effects on the growth pattern and leaf characteristics of perennial ryegrass–white clover mixtures.
Root characteristics of temperate pasture in New South Wales after grazing at three stocking rates for 30 years
Authors: Greenwood K.L. , Hutchinson K.J. 
Published: March 2003

AbstractThe distribution of length, diameter, surface area and volume of roots was measured in northern New South Wales, Australia, under temperate pasture that had been previously grazed at low and high stocking rates for 30 years; these root characteristics were compared with those of roots under ungrazed pasture. The ungrazed pasture was dominated by Phalaris (Phalaris Aquatica), whereas annual grasses and dicotyledons were a large component of the pasture at low and high stocking rates. A fine‐meshed (0.250 mm) sieve was used for separating the roots from the soil, and the root characteristics were measured using image analysis techniques. With this sieve size, root length densities were many times higher than published data for astures where a larger mesh sieve had been used for sample preparation. The lengths of root per unit of soil volume (root length densities) were high for all stocking rates and averaged 91 cm cm−3 near the soil surface (0 – 5 cm) declining to 4.0 cm cm−3 at the deepest depth measured (65–75 cm). There was a greater proportion of roots near the soil surface at the higher stocking rates. A greater proportion of fine roots occurred at the higher stocking rates, which was probably due to the differences in botanical composition. Reciprocal, power and logarithmic functions best described the distribution of root length density, root surface area density and root volume density, root surface area density and root volume desnity with depth.
Effect of allowed grazing time, inert rumen bulk and length of starvation before grazing on the weight, composition and dermentative end‐products of the rumen contents of lactating dairy cows
Authors: Chilibroste P. , Tamminga S. , Van Bruchem J. , Van der Togt P. L. 
Published: March 2003

AbstractThe effect of length of the allowed grazing time (Experiment 1), length of starvation time and placement in the rumen of inert bulk material before grazing (Experiment 2) on liquid and particulate rumen pool sizes, composition and fermentability was investigated. In Experiment 1, four lengths of allowed grazing time (1.00, 1.75, 2.50 and 3.25 h) after overnight starvation were compared. The allowed grazing time had no significant effect on total and liquid rumen pool sizes after grazing but did affect (P< 0.05) dry‐matter (DM) and organic matter (OM) rumen pool sizes. The non‐significant diferences between the volatile fatty acid (VFA) rumen pool sizes before and after 1 h of grazing may indicate a delay in the availability of the more rapidly fermentable substrate for the microorganisms. The total VFA remen pool sizes increased significantly (P< 0.01) with the allowed grazing time, which suggests that these fermentation products may be involved in the control of the grazing time in later stages during the day. Experiment 2 consisted of a factorial combination of two lengths of starvation before grazing (16.5 and 2.5 h) and the presence or absence in the rummen of 12.5 kg of a synthetic indigestible material. The duration of starvation before grazing did not affect significantly the particulate, ammonia and VFA rumen pool sizes after grazing except for propionic acid, which was reduced (P < 0.09) by the longer starvation time. The inclusion of inert bulk material in the rumen before grazing significantly reduced (P < 0.05) the total, Liquid DM, OM, and ammonia rumen pool sizes but not the VFA rumen pool sizes after grazing. High levels of ammonia as well as total rumen contents may be involved in the control of the grazing time in this experiment.
The relationship between level of sward height reduction in a rotationally grazed sward and short‐term intake rates of dairy cows
Authors: McGilloway  , Cushnahan  , Laidlaw  , Mayne  , Kilpatrick  
Published: March 2003

The objective of this study was to investigate the relationship between level of sward height reduction (SHR) and short‐term intake of herbage by lactating dairy cows offered swards differing in initial bulk density (BD). Three experiments were carried out in which cows were presented with swards representing different levels of SHR (nominally described as ungrazed, low, moderate and high). Experiments 1 and 2 differed with respect to initial sward BD [ungrazed sward 1·7 vs. 2·5 kg dry matter (DM) m−3 respectively]. Experiment 3 investigated the interaction between BD and SHR.In each experiment, sixteen Holstein/Friesian cows (fitted with excreta collection bags) grazed for a 1‐h period in 200‐m2 plots that had been grazed on the previous day to predetermined sward surface heights (SSH) (= levels of SHR). Herbage intake rates were assessed from changes in live weight, with a correction for insensible weight loss (IWL). Biting rates were recorded from visual observation. High levels of SHR were associated with a significant reduction in SSH, herbage mass and leaf fraction, and a significant increase in sward BD, stem and dead fraction, and DM concentration.Herbage intake, expressed either as DM intake per bite or DM intake per hour, declined as level of SHR increased from low to high. The level of SHR generally had no effect on biting rate. Intake rates varied from 1·9 to 4·4 kg DM h−1, whereas DM intake bite−1 ranged from 0·5 to 1·3 g. Pooled regression analysis identified SSH (P < 0·001; r2 = 0·94) as the principal determinant of DM intake bite−1. The regression equation was not significantly improved by the addition of terms for leaf fraction, BD, or herbage mass. In Experiment 3, a significant interaction between level of SHR and sward BD was observed. It is concluded that the principal factor controlling intake (g DM bite−1 or kg DM h−1), as swards are progressively grazed down, is SSH, but at a high level of SHR, sward BD also influences intake bite−1.
Long‐term effects of fertilizer on soil nutrient concentration, yield, forage quality and floristic composition of a hay meadow in the Eifel mountains, Germany
Authors: Schellberg  , Möseler  , Kühbauch  , Rademacher  
Published: March 2003

A long‐term fertilizer experiment, which was set up in 1941 on extensively grazed heathland, naturally dominated by Calluna vulgaris L. and Nardus stricta L., is presented. The turf layer was grubbed and reseeded with a grass/legume mixture, and plots were fertilized with (a) lime only as calcium (including magnesium), (2) lime and nitrogen (Ca/N), (3) lime, nitrogen and phosphorus (Ca/N/P2O5) and (4) lime, nitrogen, phosphorus and potassium (Ca/N/P2O5/KCl and Ca/N/P2O5/K2SO4). Since 1941 these experimental plots have been mown but not grazed.After 50 years of imposing the experimental treatments, dry‐matter (DM) yield was found to be positively affected by N, P and K application. Soil N and P concentrations were significantly higher in fertilized than in unfertilized plots. No differences in soil K concentration were found between the two treatments with KCl and K2SO4. Net energy concentration in the plant DM was highest with the Ca/N treatment, but differences were slight. Crude protein concentrations varied from about 110 to 170 g kg–1 DM. In all plots and all years protein concentrations were lower in the first cuts than in the second cuts.Considerable differences in floristic composition were found between different fertilizer treatments. The treatments receiving only Ca contained more than sixty species, many of them representative of oligotrophic extensively managed grassland. In fully fertilized plots, herbs were suppressed by tall‐growing grasses. In these plots the number of species was low.
The effect of N and P fertilizer application and botanical composition on the leaf/stem ratio patterns in spring in Pyrenean meadows
Authors: Calvière  , Duru  
Published: March 2003

The effect of botanical composition and nutrient availability on the relative allocation of biomass to stems and leaves in a permanent upland pasture in the central Pyrenees was assessed. Six short‐term and medium‐term fertilizer treatments (nitrogen and phosphorus) were applied to a meadow to create large differences in the proportions of the different species and a wide range of herbage nutrient status. The above‐ground herbage dry‐matter components (green leaves, sheaths and stems for grasses and dicotyledons, and senescent material) were measured for the first growth cycle.The leaf mass depended mainly on the herbage N status, whereas the stem mass depended both on the botanical composition and on the herbage N and P status. During spring growth, the proportion of leaves in the above‐ground dry matter decreased faster in plots that had the highest nutrient status or that were composed of species characteristic of nutrient‐rich (Festuca‐poor) habitats. Application of fertilizer decreased the proportion of leaves both for grasses and dicotyledons, but to a larger extent for grasses. There was a single relationship between the proportion of leaves in the above‐ground dry matter and the total mass of above‐ground dry matter, irrespective of the sampling date, the botanical composition or the herbage nutrient status. This statistical relationship resulted from (i) a faster increase in stem mass than leaf mass for a given botanical composition when the herbage nutritional status increased, (ii) a greater stem mass when the sward was composed of species usually found in nutrient‐rich habitats.
How does the vertical and horizontal structure of a perennial ryegrass and white clover sward influence grazing?
Authors: Carrère P. , Louault F. , De Faccio Carvalho P. C. , Lafarge M. , Soussana J. F. 
Published: March 2003

Mixtures of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) sown in alternate rows or in a thoroughly mixed matrix were grazed by sheep, either continuously or during short grazing tests, and were used to investigate the influence of the vertical and horizontal components of the sward structure on defoliation by sheep.In an experiment under continuous grazing, the defoliation intensity was greater for white clover compared with perennial ryegrass leaves (0·80 and 0·58 respectively). In spring, perennial ryegrass leaves were more defoliated than white clover leaves, whereas the reverse was observed in summer. The ratio of the proportion of white clover to perennial ryegrass leaves grazed was negatively correlated with the difference between the surface height of the perennial ryegrass and white clover rows in spring. In both spring and summer, white clover leaves of the same extended leaf length had a higher proportion of them grazed than perennial ryegrass leaves.In another experiment, during short grazing tests with perennial ryegrass–white clover swards that were grazed at the same sward surface height and at the same white clover content as in the previous experiment, there were no significant differences in the proportion of white clover and perennial ryegrass leaves grazed between strips of the two species and thoroughly mixed structures. The proportion of white clover leaves grazed was higher than that of perennial ryegrass leaves.These results show that the differential defoliation by sheep of perennial ryegrass and white clover leaves varies according to their vertical distribution in the mixed canopy, but is little affected by their horizontal distribution. Even small differences in sward surface height between mixed perennial ryegrass and white clover can affect diet selection by sheep to a rather large extent.
The Smith Shield: a head box for patient protection and repositioning of the surgeon's camera assistant during laparoscopic surgery
Authors: Choy Cheng C. , M. Clark James T. , Smith David , Frappell Jonathan M. 
Published: March 2003

ObjectiveTo reduce the difficulty and fatigue associated with long and complex laparoscopic procedures; to protect the face and airway of the patient from pressure from the surgeon's arms, and to allow easy operating from directly over the head end of the operating table, whilst maintaining access for the anaesthetist and monitoring equipment.DesignWe designed and patented the Smith Shield, a perspex ‘box’ with three rectangular sides that attaches over the anaesthetized patient's head. It functions as a Mayo table and surgeon's arm rest and holds equipment quivers for keeping laparoscopic instruments ready for use.Subjects and settingsWe have used the Smith Shield for all the minimal access procedures performed in our unit between January 1997 and June 1998. Other teams have also used the shield in place of the Mayo table for open procedures, most notably colposuspension.ResultsMost of the surgeons in our directorate now choose to use the shield for all but the most simple of laparoscopic procedures, as they have been so impressed with its advantages. All of our regular anaesthetists, after gaining familiarity with the correct positioning of the patient's arms and intravenous lines, comment that access to the patient for monitoring is satisfactory, and they commend the protection offered to the patient by the shield.ConclusionWe now regard the Smith Shield as an essential part of our standard laparoscopic equipment as the ability to operate comfortably from the head end of the table has greatly reduced the difficulty of complex procedures.
Laparoscopic pelvic lymphadenectomy and radical vaginal hysterectomy vs. radical abdominal hysterectomy and pelvic lymphadenectomy: a feasibility study
Authors: Tan Ai‐Ling , Mackintosh Andrew R. , Bhat Renuka 
Published: March 2003

ObjectiveTo evaluate the feasibility, complications and preliminary results of laparoscopic pelvic lymphadenectomy and radical vaginal hysterectomy for the treatment of early invasive carcinoma of the cervix.DesignA retrospective randomized clinical study.SettingThe Gynaecology Oncology Unit at the National Women's Hospital, Auckland, New Zealand.SubjectsThese were 30 women who had presented to the unit with early stage cervical cancer for whom surgery was thought to be the most appropriate primary treatment.InterventionsThe first 15 consecutive patients who were diagnosed in 1997 (group A) underwent a standard class 2 abdominal radical hysterectomy and pelvic lymphadenectomy The first 15 consecutive patients who were diagnosed in 1998 (group B) underwent a laparoscopic pelvic lymphadenectomy and a vaginal radical hysterectomy.Main outcome measuresThese included the clinical factors of operating times, blood loss, complications and hospital stay, and the pathological factors of lymph node yield, surgical margins and residual tumour size.ResultsThe operating time was slightly longer in group B (mean = 3.18 h). There were no complications in either group but blood loss was halved in group B (mean = 353 ml). Hospital stay was also shorter (mean = 6 days) compared with group A (mean = 8 days). Lymph node yield was comparable to that obtained in open surgery (mean = 18.1 nodes) and clear margins were obtained in 14 out of 15 patients.ConclusionOur preliminary results demonstrate the feasibility and safety of laparoscopic pelvic lymphadenectomy and vaginal radical hysterectomy as an alternative to open radical hysterectomy and pelvic lymphadenectomy.
An unusual clinical and histological consequence of uterine arterial embolization of a fibroid
Authors: Burnham Annabelle , Crystal Alan , Torrie E. Peter H. 
Published: March 2003

Objective Case report of an unusual clinical and histological consequence of uterine arterial embolization of a fibroid. Subject A 33‐year‐old patient with a large intramural fibroid causing menorrhagia who wished to avoid a myomectomy and/or hysterectomy. Interventions Uterine artery embolization was performed. The fibroid was partially resected from a submucosal location 6 weeks later, and a further 2 weeks later the remainder of the necrotic fibroid was removed from the uterine cavity. Results Histological examination showed that the fibroid was completely infarcted following uterine arterial embolization, and the gel foam particles were identified in the blood vessels of the fibroid. This intramural fibroid was subsequently extruded to a submucosal position where it could be resected and removed. Conclusion Uterine arterial embolization is used increasingly in the management of symptomatic uterine fibroids in women who wish to avoid a myomectomy and/or hysterectomy. We draw attention to this interesting case of sequestration and extrusion of a large intramural fibroid, with notable histological evidence of embolization.
The effect of paracervical adrenaline on blood loss in patients undergoing transcervical resection of the endometrium
Authors: Roberts Mark , Walton Stuart M. 
Published: March 2003

Objective To determine the effect of pretreatment paracervical adrenaline on blood loss in patients undergoing transcervical resection of the endometrium (TCRE). Design A double‐blind randomized controlled trial in 102 women, using adrenaline 1:200 000. To collect lost blood, a soft Malecot catheter was placed through the cervical os and connected to a drainage bag. Results Paracervical adrenaline was associated with a small reduction in blood loss that was not statistically significant and an increase in operative heart rate. Conclusions Our data do not support the routine use of paracervical adrenaline for endometrial resection. The use of a Malecot catheter to collect post‐TCRE blood loss is a new and effective method.
Endometriomas: a review of modern management
Authors: Dover Richard W. , Torode Hugh 
Published: March 2003

Objective  To review the available therapeutic options for the treatment of endometriomas with an emphasis on laparoscopic management. Design  A review of the current literature. Main outcome measures  The recurrence rate of endometriomas as assessed with the use of ultrasound or second‐look laparoscopy. Results  Medical therapy alone, or ultrasound‐guided drainage offer, a poor response rate, and should not be considered as first‐line options. Surgery has the potential to achieve good results, irrespective of whether an open or laparoscopic approach is used. In view of the recognized benefits of laparoscopic methods compared with open surgery, an endoscopic approach is recommended. The choice of laparoscopic procedure is unclear, although simple drainage alone is inadequate. Removal of the cyst lining, by either stripping the capsule, or sharp excision, has the capacity to produce a good outcome, although there are some concerns about the damage that this technique may cause to the underlying ovary. The use of electrical or laser energy to ablate the lining also has the ability to produce good outcomes, although there is no evidence from a prospective study that it leads to a lower recurrence rate than excision/stripping. Conclusions  Laparoscopic treatment is the preferred management for endometriomas, although in the absence of good clinical trials, the choice of procedure performed remains based upon clinician preference.
Adaptation of the Filshie clip applicator port to carry 5‐mm instruments without gas escape. A useful technique when unexpected pathology is encountered at laparoscopic sterilization
Authors: Clark James T. M. , Byrne Dominic L. 
Published: March 2003

Introduction  Incidental findings of pelvic pathology at the time of laparoscopic sterilization are not uncommon, and may necessitate additional instrumentation through a 5‐mm port. We describe a simple and inexpensive method of adapting the Filshie clip applicator port to carry 5‐mm instruments without losing gas pressure. When 5‐mm instrumentation is required, the instrument is placed within the digit of a sterile glove and then inserted through the 7.5‐mm Filshie clip applicator port. The glove digit remains within the port preventing gas escape whilst the instrument punctures the tip to emerge through the port to be used in the normal way. Results  We report the results of a prospective study of 50 consecutive laparoscopies. Ease of use, gas leakage rates and complications are recorded. Having demonstrated the effectiveness of this technique, we evaluated its usefulness, by performing a retrospective case review of the operating notes of 50 consecutive laparoscopic sterilizations, recording the incidence of documented pelvic pathology and instrument use. Unexpected pathology was encountered in 13 cases (26%), and instruments were required in five (10%). Conclusions  Incidental abnormalities within the pelvis are not uncommonly encountered at laparoscopic sterilization. Where instrumentation is required, our method allows utilization of the Filshie clip applicator port as an alternative to using a new 5‐mm port. The system is cheap, safe and effective. One glove can provide digits for five separate insertions if necessary. We have found this temporary laparoscopic port‐reducing method to be a simple and useful technique which meets the unexpected short‐term need for instrument use at the time of laparoscopic sterilization.