bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal variation in pathways of CH4 production and in CH4 oxidation in rice fields determined by stable carbon isotopes and specific inhibitors
Authors: Krüger Martin , Eller Gundula , Conrad Ralf , Frenzel Peter
Published: March 2003

Flooded rice fields, which are an important source of the atmospheric methane, have become a model system for the study of interactions between various microbial processes. We used a combination of stable carbon isotope measurements and application of specific inhibitors in order to investigate the importance of various methanogenic pathways and of CH4 oxidation for controlling CH4 emission. The fraction of CH4 produced from acetate and H2/CO2 was calculated from the isotopic signatures of acetate, carbon dioxide (CO2) and methane (CH4) measured in porewater, gas bubbles, in the aerenchyma of the plants and/or in incubation experiments. The calculated ratio between both pathways reflected well the ratio determined by application of methyl fluoride (CH3F) as specific inhibitor of acetate‐dependent methanogenesis. Only at the end of the season, the theoretical ratio of acetate: H2 = 2 : 1 was reached, whereas at the beginning H2/CO2‐dependent methanogenesis dominated. The isotope discrimination was different between rooted surface soil and unrooted deep soil. Root‐associated CH4 production was mainly driven by H2/CO2. Porewater CH4 was found to be a poor proxy for produced CH4.

The fraction of CH4 oxidised was calculated from the isotopic signature of CH4 produced in vitro compared to CH4 emitted in situ, corrected for the fractionation during the passage from the aerenchyma to the atmosphere. Isotope mass balances and in situ inhibition experiments with difluoromethane (CH2F2) as specific inhibitor of methanotrophic bacteria agreed that CH4 oxidation was quantitatively important at the beginning of the season, but decreased later. The seasonal pattern was consistent with the change of potential CH4 oxidation rates measured in vitro. At the end of the season, isotope techniques detected an increase of oxidation activity that was too small to be measured with the flux‐based inhibitor technique. If porewater CH4 was used as a proxy of produced CH4, neither magnitude nor seasonal pattern of in situ CH4 oxidation could be reproduced. An oxidation signal was also found in the isotopic signature of CH4 from gas bubbles that were released by natural ebullition. In contrast, bubbles stirred up from the bulk soil had preserved the isotopic signature of the originally produced CH4.
Interactive effects of nitrogen deposition, tropospheric ozone, elevated CO2 and land use history on the carbon dynamics of northern hardwood forests
Authors: Ollinger Scott V. , Aber John D. , Reich Peter B. , Freuder Rita J.
Published: March 2003

Temperate forests are affected by a wide variety of environmental factors that stem from human industrial and agricultural activities. In the north‐eastern US, important change agents include tropospheric ozone, atmospheric nitrogen deposition, elevated CO2, and historical human land use. Although each of these has received attention for its effects on forest carbon dynamics, integrated analyses that examine their combined effects are rare. To examine the relative importance of all of these factors on current forest growth and carbon balances, we included them individually and in combination in a forest ecosystem model that was applied over the period of 1700–2000 under different scenarios of air pollution and land use history.

Results suggest that historical increases in CO2 and N deposition have stimulated forest growth and carbon uptake, but to different degrees following agriculture and timber harvesting. These differences resulted from the effects of each land use scenario on soil C and N pools and on the resulting degree of growth limitations by carbon vs. nitrogen. Including tropospheric ozone in the simulations offset a substantial portion of the increases caused by CO2 and N deposition. This result is particularly relevant given that ozone pollution is widespread across much of the world and because broad‐scale spatial patterns of ozone are coupled with patterns of nitrogen oxide emissions. This was demonstrated across the study region by a significant correlation between ozone exposure and rates of N deposition and suggests that the reduction of N‐induced carbon sinks by ozone may be a common phenomenon in other regions.

Collectively, the combined effects of all physical and chemical factors we addressed produced growth estimates that were surprisingly similar to estimates obtained in the absence of any form of disturbance. The implication of this result is that intact forests may show relatively little evidence of altered growth since preindustrial times despite substantial changes in their physical and chemical environment.
Estimating the beginning day of Japanese cedar pollen release under global climate change
Authors: INOUE SATOSHI , KAWASHIMA SHIGETO , TAKAHASHI YUICHI
Published: March 2003

This study examined the effects of snowfall on the beginning day of Cryptomeria japonica pollen release and predicted it under global climate change. We used a statistical method in order to investigate when the pollen release would start and how much sooner it would be, by using data on predicted meteorological conditions under global warming in Yamagata City, Japan. Estimation accuracy was improved by multiple regression by using the mean air temperature from January to February and snowfall depth in February. Adding snowfall depth yielded more accurate estimates of the beginning day of pollen release than using air temperature alone. It is possible that the effects of heat insulation and cooling by snow delay the flowering day. Under the predicted global climate change, we expect the beginning day of pollen release to become earlier in Yamagata City. The date would be 8 February in approximately 100 years, compared with 20 February at the earliest now. Eighty years from now the date could be earlier than any date recorded so far.
In deep shade, elevated CO2 increases the vigor of tropical climbing plants
Authors: GRANADOS JULIÁN , KÖRNER CHRISTIAN
Published: March 2003

Climbing plants have profound influences on tropical forest dynamics and may take particular advantage from atmospheric CO2 enrichment, thus potentially enhancing tree turnover. Here we test the effect of a four‐step CO2‐enrichment on growth of three typical Yucatan (Mexico) climbers, across two low photon flux densities, representing typical understory situations. In pairs of two, species of Gonolobus (Asclepiadaceae), Ceratophytum (Bignoniaceae) and Thinouia (Sapindaceae) were grown on Yucatan forest soil in growth cabinets, which simulated the diurnal climate variation. Biomass increased non‐linearly in response to CO2 enrichment from 280 (preindustrial) to 420 ppm and 560 ppm, but then (700 ppm) leveled off. The relative effect of CO2‐enrichment between the two lower (280–420 ppm) CO2 concentrations was 63% at low light (LL == 42 µmol m2−2 s2−1), compared to 37% at high light (HL = 87 µmol m2−2 s2−1). This overall response of species pairs was the combined effect of linear and non‐linear responses of the individual species across CO2 treatments. Plant biomass was 61% larger in HL compared to LL. The species‐specific response depended on the neighbor, a species grew with h, irrespective of plant size. Stem length increased, but not consistently across species and light conditions. Specific stem length (SSL, length per dry mass) declined non‐linearly in all three species as CO2 concentration increased (more pronounced at LL than at HL). SLA (leaf area per unit leaf dry mass) became lower as CO2 concentration increased (more pronounced in HL). Enhanced vigor of climbers under elevated CO2 as documented here may accelerate tropical forest dynamics and lead to greater abundance of early succesional tree species. This could reduce forest carbon stocking in the long run.
Effects of extended wilting, shading and chemical additives on the fatty acids in laboratory grass silages
Authors: Dewhurst  , King
Published: March 2003

This work investigated the range of fatty acid concentrations in grass silages made from the regrowth of perennial ryegrass Lolium perenne using different techniques involving combinations of shading of the crop before cutting, wilting and the use of chemical additives. The effects of the different silage additives on overall fermentation were large, with many of the formic acid and formalin‐treated silages having a very restricted fermentation. Nonetheless, effects on levels and proportions of fatty acids were numerically small. The major differences between silages were generated during field operations (shading and wilting), with little further changes in fatty acids within the silage clamp. The extended wilt had the most dramatic effect on fatty acids with a marked reduction in both total fatty acids (24·6 vs. 17·5 g kg−1 dry matter; s.e.d. = 0·65, P < 0·001) as well as in the proportion of total fatty acids as α‐linolenic acid (C18:3n‐3; 0·55 vs. 0·48; s.e.d. = 0·013, P < 0·01). Shading the grass with a black plastic sheet for 24 h before cutting had a similar effect.
Competition in perennial ryegrass–white clover mixtures under cutting. 1. Dry‐matter yield, species composition and nitrogen fixation
Authors: Elgersma  , Nassiri  , Schlepers
Published: March 2003

Persistence of white clover (Trifolium repens) in mixtures was studied in a long‐term experiment. Mixtures of two cultivars of perennial ryegrass (Lolium perenne) with contrasting growth habits and three white clover cultivars differing in leaf size were sown in 1991 and evaluated at two cutting frequencies. During 1995 and 1996 mixtures with large‐leaved white clover cv. Alice had the highest dry‐matter (DM) content, clover and N yield, and the highest white clover content, and mixtures with medium‐leaved Retor the lowest, whereas mixtures with small‐leaved Gwenda yielded most grass DM. In 1995 averaged over cutting treatments and mixtures, the mixtures yielded 11·8 t DM ha−1 with a white clover content of 0·6; the apparent N fixation was 393 kg N ha−1. In 1996 these values declined to 8·5 t DM ha−1, 0·48 white clover and 236 kg N ha−1. There was no significant effect of cutting frequency on DM yield or white clover content, whereas the effects of grass cultivar were not consistent.

In spring there was a peak in the DM production of the mixtures, coinciding with a peak in production of the grass component. However, in summer and autumn the seasonal pattern of DM production of the mixtures was similar to that of the white clover component. Both cultivars of perennial ryegrass showed the same seasonal response, but the seasonal growth pattern of white clover differed slightly between clover cultivars and cutting treatments. In later years only one cutting frequency was imposed, and no yield measurements were taken. White clover was judged to have performed well during 1997; the clover content in September was very high (0·76), whereas in October 1998 it was 0·45. Mixtures with Alice contained most white clover. Despite fluctuations in white clover content during 1991–98, all clover cultivars had persisted 7 years after sowing, irrespective of companion grass cultivar, at both cutting treatments.
Effect of annual stocking rates in grass and maize+rye system on production by dairy cows
Authors: Mosquera‐Losada R. , González‐Rodríguez A.
Published: March 2003

The effects on the production from dairy cows of two annual stocking rates (2.5 and 3.0 cows ha−1) and two systems (grass and maize+rye) were examined. The experiement included three treatments: Treatment A was a grass system with an annual stocking rate of 2.5 cows ha−1 and Treatments B and C were maize+rye systems with a stocking rate of 2.5 and 3.0 cows ha−1 respectively. There were twenty cows per treatment and the total area of the system was 22 ha. Treatment A had 4.05 ha of grass silage area, Treatment B had 0.8 ha of grass silage area and 3.2 ha designated to silage crops (maize+rye), whereas Treatment C had 0.4 ha of grass silage area and 2.7 ha of silage crops. Maize silage had a higher nutritive value that the rye or grass silage. The greter production from the maize+rye crops allowed the silage needs of the cows to be met in systems with a seasonal herbage production when stocking rates are higher than for grass‐only systems. Rye plus maize system allowed higher stocking rates (2.7 cows per ha) than grass‐only system (2.1 cows per ha) because of more efficident use of land resources. Lower stocking rates and grass‐only systems increased milk production per cow but not per hectare in comparison with rye plus maize systems.
Dry‐matter yield and herbage quality of a perennial ryegrass/white clover sward in a rotational grazing and cutting system
Authors: Schils  , Vellinga  , Kraak
Published: March 2003

The expected reduction in the use of fertilizer nitrogen (N) on grassland in the Netherlands has led to renewed interest in white clover. Therefore, the performance of a newly sown perennial ryegrass/white clover sward on clay soil was assessed during 4 consecutive years. The experiment consisted of all combinations of two defoliation systems, i.e. one or two silage cuts per year (S1, S2), spring N application rate, i.e. 0 or 50 kg ha−1 year−1 (N0, N50), and the management system, i.e. rotational grazing and cutting, or cutting only (RGC, CO). The overall mean white clover cover was 30%. All treatments affected white clover cover, which was 8% higher with S2 than with S1, 6% higher with N0 than with N50 and 12% higher with CO than with RGC. The overall mean annual dry‐matter (DM) yield (13·1 t ha−1 year−1) was significantly affected only by the management system: in two relatively wetter years, the annual DM yield was 1·19 t ha−1 higher with RGC than with CO, whereas there was no difference in two relatively drier years. Nitrogen application increased the DM yield in the first cut by 7·0 kg kg−1 N applied, but had no significant effect on the annual DM yield. Herbage quality was not affected by the experimental treatments. The average in vitro organic matter digestibility was 0.801, and the average crude protein content was 193 g kg−1 DM. With the expected reduction in the use of fertilizer N, perennial ryegrass/white clover swards should be seriously considered as an alternative option to perennial ryegrass swards on these clay soils.
Hay production from lowland semi‐natural grasslands: a review of implications for ruminant livestock systems
Authors: Tallowin  , Jefferson
Published: March 2003

Data on total, seasonal and between‐year variability in the productivity and nutritional quality of cut forages obtained from a range of lowland semi‐natural grasslands are reviewed.

Dry‐matter production, as hay, from unfertilized species‐rich semi‐natural grasslands ranged from less than 20% to about 80% of the production that might be expected from agriculturally improved and intensively managed grasslands. Unfertilized species‐rich grasslands had lower growth rates, reflecting low nutrient availability in spring and early summer. Low soil phosphorus availability appears to be a key factor allowing high species‐richness to be maintained.

The in vitro digestibilities of herbage cut for hay from semi‐natural grasslands were 20%, or more, below values for conserved forages from intensively managed grassland. When losses incurred during the hay‐making process were taken into account, then the nitrogen content of hays from many semi‐natural grasslands appear to be sub‐optimal for productive livestock. Metabolizable energy values of herbage cut for hay were 10–40% below values for intensively managed conserved grass. Phosphorus content of forages from most species‐rich grasslands was either below the metabolic requirement of livestock or inadequate to sustain high individual animal performance. Potential problems associated with supplementation of the diet with phosphorus, and with high calcium‐to‐phosphorus ratios, are discussed. Although potassium content of most of the herbage cut for hay was adequate for productive ruminant livestock, exceptions arise with hay cut after July. The magnesium content of cut herbage from some semi‐natural grasslands was below an adequate level for productive livestock. Most cut herbage appeared to contain adequate amounts of sodium. Inadequacy of the mineral content of hays from semi‐natural grasslands for ruminant livestock will be exacerbated by nutrient losses incurred during the hay‐making process and particularly so when hay‐ making is prolonged by wet weather.

Few feeding studies using hays from semi‐natural grasslands of high nature conservation interest have been conducted. Lack of such data makes it difficult to plan any integrated use of these hays in ruminant feed budgets for livestock systems.
Effect of swath treatment on water loss during field‐wilting and on feeding value of perennial ryegrass silage
Authors: Wilkinson  , Hill  , Leaver
Published: March 2003

The effect of spreading mown perennial ryegrass (Lolium perenne) herbage over the total ground area on water loss during field‐wilting was compared with leaving herbage in swaths (three swaths put together into one, occupying 0·18 of ground area) in three experiments. Spread crops were not tedded during wilting but were rowed up immediately before harvest. In all experiments, conventional silage‐making equipment was used on a field scale. Feeding value was assessed with lactating dairy cows and growing heifers (Experiment 1) and sheep (Experiment 3). The periods of field wilting were 48 h (Experiment 1), 24 h (Experiment 2) and both 24 h and 48 h (Experiment 3). Spreading the crop was associated with larger increases in loss of water in all three experiments compared with leaving grass in swaths. Losses of dry matter (DM) during wilting were similar in Experiment 2 but were higher for the swathed crop wilted for 48 h than for 24 h in Experiment 3. Spreading resulted in restricted fermentations associated with higher crop DM contents at ensiling. In Experiment 1 the concentrations of DM, ash and water‐soluble carbohydrate in silage were higher (P < 0·001) for spreading the crop and the concentrations of crude protein and neutral‐detergent fibre were lower (P < 0·05) than for swathed material. In Experiment 3, spreading was associated with higher concentrations of water‐soluble carbohydrates and ethanol and lower concentrations of fermentation acids, ammonia‐N and neutralizing value in silage. Voluntary DM intake of silage by dairy cows and heifers was higher for spread than for swathed material (P < 0·05), but in Experiment 3 (sheep) there were no significant differences between treatments in voluntary intake of DM. The increased intake by dairy cows of silage from spread herbage was reflected in increased concentrations of milk fat (P < 0·01) and protein (P < 0·05) but not in milk yield (P > 0·05). It is concluded that spreading herbage during field wilting prior to ensiling accelerates water loss and has the potential to improve the feeding value of the ensiled product.
Control of Molinia caerulea on moorland
Authors: Todd  , Phillips  , Putwain  , Marrs
Published: March 2003

Burning, grazing and herbicide (glyphosate) treatments were applied in factorial combination to Molinia‐dominated moorland in three regions of England: Exmoor, North Peak and Yorkshire Dales. In each region, agri‐environment schemes are in place in an attempt to reduce Molinia and encourage the development of dwarf shrub vegetation. Within each region, the same experiment was carried out on two types of vegetation (Molinia‐dominated ‘white’ moorland and a mixture of Molinia and Calluna‘grey’ moorland).

Of the treatments applied, glyphosate had the most significant effect on Molinia at all study sites. There was little difference between the use of low and high application rates, 0·27 and 0·54 kg ai ha–1 respectively. The cover of dwarf shrubs, including Calluna in the ‘grey’ sites, was affected by the herbicide treatment in two regions, but there was no significant reduction in the North Peak. Some Calluna plants were killed or damaged by glyphosate.

Two techniques for the re‐establishment of Calluna were also investigated in the Molinia‐dominated ‘white’ moorland: the two treatments applied in factorial combination were (1) removal of Molinia leaf litter by raking; and (2) application of Calluna seed. Greater Calluna seedling densities were found in the plots in which herbicide was applied, the Molinia litter was removed and seed added.
An evaluation of callus induction and plant regeneration in twenty‐five turf‐type tall fescue (Festuca arundinacea Schreb.) cultivars
Authors: Bai Y. , Qu R.
Published: March 2003

In order to investigate the genetic variation in tissue culture response and to find the cultivars with high regeneration ability for genetic transformation, twenty‐five turf‐type tall fescue (Festuca arundinacea Schreb.) cultivars, including many elite ones released recently, were evaluated for their callus induction and plant regeneration responses. Callus induction was initiated from mature seeds on a Murashige and Skoog (MS) medium containing 9·0 mg l–1 2,4‐dichlorophenoxyacetic acid (2,4‐D). Induced calli were subcultured on the same medium with 2·0 mg l–1 2,4‐D and then transferred to a MS medium supplemented with 2·5 mg l–1 6‐benzylaminopurine (BAP) for plant regeneration. Significant differences were observed among the twenty‐five cultivars in both callus induction and plant regeneration (P < 0·001). Callus induction rate of viable seeds varied from 4·4% to 51·9%. Callus regeneration rates ranged from 16·7% to 58·8%. Overall regeneration rates (number of regenerated calli over number of cultured viable seeds) ranged from 1% to 22%. Approximately 94% of the regenerants were green plantlets.
Bite dimensions for cattle grazing herbage at low levels of depletion
Authors: Ungar E. D. , Ravid N. , Bruckental I.
Published: March 2003

The processes that occur during the depletion of a single feeding station by grazing cattle are important to our understanding of intake at larger spatial scales. Factorial experiments were conducted in which feeding stations of different sizes were grazed individually by cattle to various levels of depletion, defined as the number of bites removed. Feeding stations in Experiment 1 (alfalfa) measured 0·11, 0·24 and 0·45 m2, and the numbers of bites removed for depletion levels 1–3 were 35, 70 and 104 m−2 respectively. Feeding stations in Experiment 2 (oats) measured 0·11 and 0·24 m2, and the numbers of bites were 45, 95 and 140 m−2 offered. In both experiments a fourth depletion level (not included in the analysis of variance) determined the maximum voluntary depletion, and exceeded 250 bites m−2 offered. Initial sward height was 20 cm. Bite dimensions were derived from the frequency distribution of residual herbage heights. Treatments were replicated over six and four animals of approximately 500 kg live weight in Experiments 1 and 2 respectively.

The mean residual herbage height and the frequency distribution of residual heights indicated that bites were removed predominantly from the top grazing horizon at depletion levels 1–3, with a mean effective bite depth of 8·6 cm. Nevertheless, at the same depletion levels, the mean effective bite area declined from 148 to 87 cm2 in Experiment 1 (alfalfa, Medicago sativa L.) and from 86 to 58 cm2 in Experiment 2 (oats, Avena sativa L.). Feeding station size did not significantly affect mean effective bite area in either experiment.

Simulation was used to examine the implications of various overlap rules (from completely random to highly systematic) for within‐grazing‐horizon placement of a circular bite of constant potential area. These rules shaped the relationship between mean effective bite area and number of bites removed per unit sward area offered. Bite placement in which permissible overlap became progressively more lenient as the grazing horizon was depleted, and, with acceptable estimates of potential bite area, yielded results that were similar, though not identical, to those measured. These results can help understanding of the factors that determine the intake gain function at a single feeding station.
The effects of rate and timing of application of fertilizer nitrogen in late summer on herbage mass and chemical composition of perennial ryegrass swards over the winter period in Northern Ireland
Authors: Binnie R. C. , Mayne C. S. , Laidlaw A. S.
Published: March 2003

A small‐plot experiment was carried out in Northern Ireland on a predominantly perennial ryegrass sward over the period July 1993 to March 1994 to investigate the effect of timing and rate of fertilizer nitrogen (N) application on herbage mass and its chemical composition over the winter period. Eighty treatment combinations, involving four N fertilizer application dates (28 July, 9 and 30 August and 20 September 1993), four rates of N fertilizer (0, 30, 60 and 90 kg N ha−1) and five harvest dates (1 October, 1 November, 1 December 1993, 1 February and 1 March 1994), were replicated three times in a randomized block design experiment.

N application increased herbage mass at each of the harvest dates, but in general there was a decrease in response to N with increasing rate of N and delay in time of application. Mean responses to N applications were 13·0, 11·5 and 9·5 kg DM kg−1 N at 30, 60 and 90 kg N ha−1 respectively. Delaying N application, which also reduced the length of the period of growth, reduced the mean response to N fertilizer from 14·3 to 7·4 kg DM kg−1 N for N applied on 28 July and 20 September respectively.

Increasing rate of N application increased the N concentration and reduced the dry‐matter (DM) content and water‐soluble carbohydrate (WSC) concentration of the herbage but had little effect on the acid‐detergent fibre (ADF) concentration. Delaying N application increased N concentration and reduced DM content of the herbage. The effect of date of N application on WSC concentration varied between harvests.

A decrease in herbage mass occurred from November onwards which was associated with a decrease in the proportion of live leaf and stem material and an increase in the proportion of dead material in the sward.

It is concluded that there is considerable potential to increase the herbage mass available for autumn/early winter grazing by applying up to 60 kg N ha−1 in early September.
Fermentation characteristics and aerobic stability of grass silage inoculated with Lactobacillus buchneri, with or without homofermentative lactic acid bacteria
Authors: Driehuis F. , Oude Elferink S. J. W. H. , Van Wikselaar P. G.
Published: March 2003

Aerobic spoilage by yeasts and moulds is a major cause of reduced nutritional value of silage and increases the risk of potential pathogenic microorganisms. Recent studies have shown that inoculation with Lactobacillus buchneri inhibits yeast growth and reduces the susceptibility to aerobic spoilage of various ensiled forages. The aim of this study was to determine whether these effects are retained when L. buchneri is added in combination with homofermentative lactic acid bacteria. In three experiments, silages were produced from perennial ryegrass [240–421 g kg−1 dry matter (DM)] inoculated with L. buchneri or L. buchneri plus a mixture of Pediococcus pentosaceus and Lactobacillus plantarum (inoculant PL). Uninoculated silage and silage inoculated with PL alone served as controls. Silages were examined for pH and DM loss in the course of ensilage and chemical and microbiological composition and aerobic stability after 3–4 months. L. buchneri plus PL and PL alone increased the initial rate of pH decline. L. buchneri alone and L. buchneri plus PL enhanced aerobic stability and, in general, reduced yeast and mould counts. In addition, these inoculants increased the final pH and DM loss and the concentrations of acetic acid and 1,2‐propanediol (or propionic acid and 1‐propanol instead of 1,2‐propanediol), and decreased the concentration of lactic acid. The effects of L. buchneri on fermentation products increased with decreasing DM content. In silages of less than 270 g kg−1 DM, L. buchneri increased the ammonia‐N concentration. It is suggested that this was associated with the relatively high final pH resulting from the high metabolic activity of L. buchneri in these silages.
Matching grass supply to grazing patterns for dairy cows
Authors: Orr R. J. , Rutter S. M. , Penning P. D. , Rook A. J.
Published: March 2003

Four groups of five spring‐calving Holstein–Friesian cows were given a daily grass allowance in a strip‐grazing system after either morning (AM; two groups) or afternoon (PM; two groups) milking over a 10‐week period. The dry‐matter (DM) concentration of the grass tended to be higher after afternoon milking [AM, 178 vs. PM, 197 g DM (s.e.d. 5·32) kg–1 fresh matter], and water‐soluble carbohydrate concentrations were significantly higher [AM, 175 vs. PM, 204 g kg–1 DM (s.e.d. 6·67)]. Although the total times spent grazing (AM, 461 vs. PM, 462 min day–1) were similar for both groups, cows receiving their allocation in the afternoon had a longer evening meal (>4 h duration) compared with those receiving their allocation in the morning (2–3 h), which also spent more time ruminating [AM, 454 vs. PM, 433 min day–1 (s.e.d. 1·80)]. This short‐term study demonstrated how a relatively simple change in management practice in strip‐grazing systems could benefit milk yield and pasture utilization. This is because the DM and water‐soluble carbohydrate contents of the herbage are higher in the evening than in the morning, and this is when grazing animals concentrate much of their daily grazing activity.
Pattern of herbage intake rate and bite dimensions of rotationally grazed dairy cows as sward height declines
Authors: Barrett P. D. , Laidlaw A. S. , Mayne C. S. , Christie H.
Published: March 2003

To allow improved prediction of daily herbage intake of dairy cows in rotational grazing systems, intake behaviour was assessed throughout the day in 24‐h paddocks. Herbage intake in 16 lactating Holstein–Friesian cows was assessed using the short‐term (1‐h) weight gain method at four predetermined natural meal times throughout the day (early morning, T1; late morning, T2; mid‐afternoon, T3; and early evening, T4). The study comprised two 4‐day experiments, each with a cross‐over design of four blocks. In both experiments, cows grazed a 24‐h paddock daily, and the effect of the immediately previous grazing experience on intake behaviour was investigated throughout the day, taking account of daily fluctuations in the short‐term physiological condition of the cows. Experiment 1 was carried out to investigate overall grazing behaviour during meals as a sward is progressively depleted during the day, with intake being assessed within the paddock and, hence, on a depleted sward. Experiment 2 similarly investigated the effect of sward depletion and physiological condition throughout the day on intake, but cows were removed to fresh, undefoliated swards during intake measurement periods; thus, intake rate was not influenced by differences in sward condition. Intake behaviour from both experiments was compared to establish the effect on herbage intake of changes in sward state and non‐sward factors. In Experiment 1, sward surface height, available herbage mass, proportion of leaf and green leaf mass declined as the day progressed. Bite mass declined with sward depletion, and mean intake rate was 1·64 kg dry matter (DM) h–1, which was significantly lower at T3 (P < 0·01) than during other meals. In Experiment 2, plot sward conditions did not change throughout the day, and intake behaviour also remained constant, with a mean intake rate of 2·11 kg DM h–1. Mean bite depth as a proportion of pregrazing extended tiller height was constant throughout the day (mean 0·32). The results show that, although cows grazed throughout the day on progressively depleted swards, indicative of rotationally grazed paddocks (Experiment 1), bite mass declined linearly and intake behaviour was variable. However, where intake was assessed on high‐quality, undefoliated swards (Experiment 2), intake behaviour was similar regardless of the time of day and the immediately previous experience. There was some indication of an interaction between the effects of the sward and the physiological condition of the animal on herbage intake.
Plant species richness, functional type and soil properties of grasslands and allied vegetation in English Environmentally Sensitive Areas
Authors: Critchley C. N. R. , Chambers B. J. , Fowbert J. A. , Bhogal A. , Rose S. C. , Sanderson R. A.
Published: March 2003

To facilitate the maintenance and restoration of semi‐natural grasslands, it is important to understand their relationships with soil properties. Semi‐natural grasslands typically have a high incidence of stress‐tolerant species (measured here by high stress radius values), but not all have high species richness. Species richness and stress radius values were related to soil pH, Olsen extractable phosphorus (P), extractable potassium (K) and magnesium (Mg), total nitrogen (N) and organic matter (OM) at 571 sites representing a wide range oftemperate grasslands. Highest species richness (>30 m−2) occurred at pH > 6 and 4–15 mg l−1 P, but species richness was also highly variable at 4–15 mg l−1 P. At pH < 5, species richness was low (<20 m−2). Stress radius values were highest (mainly calcareous and heath grasslands and mires) at pH c. 8·0 and < 5·0, and at the lowest soil P levels (<5 mg l−1). A wide range of stress radius values occurred at low soil P levels because appropriate management is also needed to maintain semi‐natural grasslands. Reducing soil P is difficult in practice, so grassland restoration in the presence of elevated soil‐extractable P levels merits re‐assessment.
Pitfall of the LASH technique: an unsuspected leiomyosarcoma removed after morcellation
Authors: Anaf Vincent , Simon Philippe , Govaerts Isabelle , Noël Jean‐Christophe , Rodesch Frédéric
Published: March 2003

Mesenchymal uterine tumours can mimic benign uterine tumours and are therefore often diagnosed postoperatively. We report the first case of intra‐abdominally morcellated unsuspected leiomyosarcoma in the laparoscopic‐assisted supracervical hysterectomy (LASH) technique. This article discusses the prevention of spillage and the inadequate oncologic management which are specific to this technique in case of leiomyosarcoma or stromal sarcoma.
A technique to avoid spillage of cysts during extraction at laparoscopy
Authors: Healey Martin , Mayer Peter , Geoghegan Tony
Published: March 2003

This paper describes a simple method that can be used at laparoscopy to remove ovarian cysts while minimizing the risk of spillage. As with all surgery, careful technique produces the best results.
Endometrial resection: factors affecting long‐term success
Authors: Gandhi Saurabh V. , Fear Kenneth B. C. , Sturdee David W.
Published: March 2003

Objective

To identify prognostic factors for the long‐term success of transcervical resection of endometrium (TCRE).

Design

A retrospective analysis.

Setting

Department of Obstetrics and Gynaecology, Solihull Hospital, Solihull, West Midlands, UK.

Subjects

301 patients, who chose endometrial resection rather than hysterectomy and who underwent their first TCRE between 17 October 1989 and 31 December 1994.

Interventions

Endometrial resection carried out by one surgeon (D.W.S.).

Main outcome measures

Patient satisfaction, degree of bleeding and degree of pain, 1–6 years following TCRE. The procedure was considered to have failed if hysterectomy was necessary later.

Results

301 patients underwent a total of 329 procedures (TCRE) and were followed up for 1–6 years (mean 2.8). Complications were few and there was no death or major morbidity. About 80% of patients were satisfied with the procedure and had either amenorrhoea (34%), scanty periods (33%) or moderate/acceptable periods (14%). The incidence of hysterectomy because of the failure of this procedure was 15%. The success rate was significantly higher in the older age group (>40 years); in those without previous moderate or severe dysmenorrhoea; where histological examination of the endometrial chippings did not show any abnormality; where further surgery such as diagnostic hysteroscopy, laparoscopy or repeat resection (repeat TCRE) was not required, and with increasing operator experience.

Conclusion

TCRE should remain a useful option in the management of women with menorrhagia. Greater awareness of the prognostic factors identified in this study will improve preoperative counselling and the appropriate selection of patients for TCRE.
Endometrial resection: a diagnostic tool in postmenopausal women
Authors: Franchini Mario , Cianferoni Luciano
Published: March 2003

Objective

To determine the diagnostic role of hysteroscopic endometrial resection in symptomatic postmenopausal women.

Design

Retrospective study.

Setting

Gynaecology department at a general hospital.

Patients

150 postmenopausal women with abnormal uterine bleeding.

Interventions

Hysteroscopic transcervical resection of endometrium under general or spinal anaesthesia.

Results

Eight endometrial carcinomas were detected in endometrial chips and were managed with simple hysterectomy. A benign organic cause was noted in 131 cases, and 11 women had atrophic endometrium. All 142 postmenopausal women with a benign lesion were satisfied with their treatment and had no recurrence of abnormal bleeding during a mean follow up of 28 months.

Conclusion

Endometrial transcervical resection is a reasonable clinical strategy for single‐procedure evaluation and treatment in postmenopausal women with abnormal uterine bleeding.
Complications of first entry: a pospective laparoscopy audit
Authors: Richardson Robert E. , Sutton Christopher J.G.
Published: March 2003

Aim

To record the incidence of both minor and major complications associated with first entry at laparoscopy and to compare the volume and pressure methods of insufflation.

Design

Prospective clinical study.

Subjects and methods

All patients undergoing gynaecological laparoscopy at the Chelsea and Westminster Hospital between 1 January and 31 December 1997. Surgeons completed a standard form at the time of the procedure. Two techniques of abdominal insufflation were compared; the volume technique when a set volume defined the endpoint of abdominal insufflation and the pressure technique when a set intra‐abdominal pressure was the endpoint.

Results

The database includes 836 patients. When a pneumoperitoneum was established, the pressure technique was used in 55.8% of cases and the volume technique in 38.0%. The average volume used in the pressure group was significantly greater (4.33 vs. 2.82 l, P > 0.01). The main complications were failed laparoscopy, extraperitoneal and omental emphysema and bowel injury. There were no vascular injuries at first entry. The rate of complications varied with operator experience. Veress needle insertion was successful at the first attempt in 86.9% of procedures, with a complication rate of 0.82%. The complication rate rose with increasing number of attempts. Extraperitoneal insufflation occurred in 4.1%. The complication rate in the pressure group was significantly lower (4.1% vs. 8.2%, 0.05 > P > 0.02). Laparoscopy was abandoned in five cases, and in all of the latter the volume technique had been used. Three patients experienced bowel complications requiring laparotomy. Three patients were readmitted with umbilical hernias.

Conclusions

As the pressure method of insufflation is associated with a lower complication rate, it should be adopted. Use of this method did not, however, protect against bowel complications. Such complications occurred in high risk patients following uncomplicated Veress needle entry. Strategies to avoid such complications should be employed.
Optical Veress as an entry technique
Authors: McGurgan  , O'donovan
Published: March 2003

Objective

To review the advances in instruments designed for safer entry into the abdominal cavity.

Design

A systematic review of the literature, including a Medline search of the period from 1966 to February 1999, using the words: laparoscopic, mini, micro, entry, Veress needle, optical, safety and methods.

Results

There are approximately 0.4 Veress needle‐related injuries per 1000 procedures. The modified ‘optical’ Veress instruments are designed to further decrease this rate. Despite extensive studies demonstrating the use of the latter, there are no large‐scale, well‐designed trials to confirm their superiority over the conventional Veress.

Conclusion

Veress needle‐related injuries are rare, but their sequelae can be fatal. Many of the alternative instruments have potential advantages over the Veress needle, but lack of quality research means that they are not yet validated. This must be done by well‐planned trials as soon as possible.
Open laparoscopy as a method of access in laparoscopic surgery
Authors: Hasson Harrith M.
Published: March 2003

Objective

To describe the technique of open laparoscopy and compare the rates of its complications to those of closed laparoscopy.

Design

Medline search, review of the literature and the author's experience.

Results

For open laparoscopy, the rate of umbilical infection in 15 622 cases was 0.4%, that of bowel injury in 20 335 cases was 0.1%, based on prospective, retrospective studies and a mail survey. Prospective and retrospective studies dealing with closed laparoscopy reported the following complication rates: umbilical infection: 1% of 4377 cases; vascular injury: 0.2% of 94 863 cases: visceral injury: 0.2% of 91 272 cases. The operating time for open and closed laparoscopy were substantially similar.

Conclusion

Open laparoscopy is advocated as the preferred method of access for laparoscopic surgery.
Endometrial abnormalities in breast cancer patients with tamoxifen therapy
Authors: Prevedourakis Constantin , Makris Nikolas , Xygakis Antonios , Dachlythras Marios , Michalas Stelios
Published: March 2003

Objective

Evaluation of the effect of tamoxifen therapy on endometrium in patients who have previously undergone surgery for breast cancer.

Design

An analysis of hysteroscopic findings and their correlation with those from previous vaginal ultrasonography and subsequent endometrial sampling.

Setting

The hysteroscopy unit of a university clinic.

Subjects

64 patients referred from the breast clinic, who had previously undergone surgery for breast cancer and who were receiving adjuvant tamoxifen therapy, with either suspicious findings on routine vaginal ultrasonography or abnormal uterine bleeding. Of the patients, 22 were premenopausal (group A) and 42 postmenopausal (group B). Each group was divided in two subgroups, comprising either symptomatic patients (groups A1 and B1) or asymptomatic patients (groups A2 and B2).

Intervention:

Diagnostic hysteroscopy.

Results

All six patients of group A1 were found to have hyperplastic endometrium on hysteroscopy. Subsequent biopsy after dilation and curettage (D&C) revealed simple endometrial hyperplasia in all samples, plus endometrial polyps in two cases. Despite suspicious appearances on vaginal ultrasonography, all 16 asymptomatic premenopausal patients (group A2) were found on hysteroscopy to have normal endometrium. Among the 29 patients with postmenopausal uterine bleeding (group B1) 22 showed hyperplastic endometrial findings on hysteroscopy. The histopathological results from the subsequent D&C, confirmed the hysteroscopic findings, showing various degrees of endometrial hyperplasia and three adenocarcinomas (4.7% of the total number of patients or 10.3% of those with postmenopausal bleeding). Normal or atrophic endometrium was observed in nine of the 13 patients in group B2; there was one polyp, and three cases of hyperplastic endometrium, which were found to be simple hyperplasia on pathological investigation.

Conclusions

Monitoring of the uterine cavity in patients receiving tamoxifen therapy is mandatory, especially where there is postmenopausal bleeding. Hysteroscopy findings display a considerably higher degree of correlation with endometrial pathology results, than do vaginal ultrasonography findings.
Surgical treatment of prolapse through a laparoscospic retroperitoneal approach: a new route for sacral colpopexy
Authors: Cosson  , Vinatier  , Occelli  , Querleu  , Crepin
Published: March 2003

The retroperitoneal approach was first described and used several years ago for the staging and treatment of gynaecological malignancies, or for Burch laparoscopic colposuspension procedures. We here describe an original technique for the correction of genital prolapse or for performing a laparoscopic sacral colpopexy using a retroperitoneal approach. Our technique involves fixation of the vagina to the sacral promontory using prosthetic material, followed by paravaginal repair and Burch's colposuspension. This route allows for complete treatment of the three components of the pelvic support system and has both advantages and weaknesses. The latter are discussed, followed by suggestions concerning situations where this approach might be preferred to standard techniques.
Laparoscopic excision of adenomatoid tumour at cornu of the uterus and cornual (interstitial) pregnancy
Authors: Chern B. , Tan K. H.
Published: March 2003

We report a rare case of cornual (interstitial) ectopic pregnancy associated with a cornual adenomatoid tumour, both of which were resected together laparoscopically.
Sequestration and extrusion of intramural fibroids following arterial embolization: a case series
Authors: Jones Kevin , Walker Woodruff J. , Sutton Christopher
Published: March 2003

Objective 

To report a case series of fibroids that were sequestered and extruded following arterial embolization.

Methods 

The clinical records of six patients were reviewed.

Results 

The clinical and radiological findings demonstrated large fibroids which were sequestered and extruded following arterial embolization.

Conclusion 

Fibroids can be passed into the uterine cavity following uterine artery embolization.
Bowel injuries during gynaecological laparoscopy: a multinational survey
Authors: Brosens Ivo , Gordon Alan
Published: March 2003

Objective

To use the experience of an international group of gynaecological laparoscopists to evaluate the prevalence, causes, sites, management and outcomes of bowel injury occurring during or as a result of laparoscopy.

Design

A questionnaire was sent to members of the International Society for Gynecologic Endoscopy (ISGE) requesting details of all laparoscopies complicated by bowel trauma and performed by them over a 2‐year period. One year was retrospective and one prospective.

Results

A total of 135 members (24%) replied and reported 45 bowel injuries. The estimated prevalence was 1 in 1652 level 1 laparoscopies and 1 in 280 levels 2 and 3 laparoscopies combined. Injuries were caused by the Veress needle, primary trocar, forceps, scissors and by electro‐ and laser surgery. Adhesions from previous surgery or endometriosis were present in 78% of cases. Bowel trauma was statistically significantly related to the experience of the surgeon, defined by a cut‐off at 100 procedures per year. In experienced hands trauma occurred as frequently during access as during the surgical procedure. The diagnosis was made during the laparoscopy in 38 cases. Expectant treatment was carried out in four cases after Veress needle injury without consequences, laparoscopic suturing in eight cases and conversion to laparotomy in 26 cases. The diagnosis was delayed in seven patients (15%) of whom two (28%) died 7 days after surgery without any further intervention.

Conclusions

Bowel injury during gynaecological laparoscopy is significantly related to the experience of the surgeon. With the experienced group, bowel trauma occurs as frequently during access as during the surgical procedure. The occurrence of two deaths in our study suggests that the mortality due to bowel trauma may be underestimated in reports from highly privileged societies.