ALBERT

Notes: Abstract. A model has been developed based on multiple regression which explains 95% of the variation in nitrate loading of the major rivers in the 4453 km2 Lough Neagh catchment for the years 1971–1987. The model relates loading of nitrate in the hydrological year to fertilizer usage, previous summer rainfall, summer temperature of the current year and December-May flow. It indicates that there is an increase in nitrate loading associated with fertilizer usage, and that the equivalent of 13% of nitrogen fertilizer that is lost as leachate comprises 50% of the river loadings.

Notes: Abstract. The loess plateau in China is the most developed region of loess in the world in terms of extent, thickness and depositional sequence. It is also the region with the most serious soil erosion in the world. This paper reviews the factors and reasons for soil erosion in this area. The loess is prone to vertical cleavage and its surface soils are soft and loose. Rainstorms are frequent with intense rain concentrated during the summer. Irrational land use and exploitive management have been carried out for thousands of years and express themselves through the loss of grassland and natural forests. Finally, some soil conservation schemes for use in the loess plateau are suggested.

Notes: Book reviews in this article: Land resources in the Loess Plateau of China Editor Professor Zhou Xianmo (S.M. Chou).

Notes: Abstract. The WOFOST simulation model is a tool for analysing the growth and production of field crops under a wide range of weather and soil conditions. Such an analysis is important first to assess to what extent crop production is limited by the factors of light, moisture and macro-nutrients, and second to estimate what improvements are possible. The theoretical concept of a production situation, as modelled by WOFOST, is explained, as is the hierarchy of potential production and water-limited and nutrient-limited production situations in the analysis. The organization of the computer files in the model, the structure of the FORTRAN source program and the available standard sets of data are described briefly.

Notes: Abstract. Assuming that other sources of error can be neglected, the reliability of a land suitability classification depends on the homogeneity of physiographically delineated map units with regard to land qualities. The map unit homogeneity of a small area in France was estimated using 64 observation points, arranged according to a nested sampling scheme, followed by nested analysis of variance.The analysis shows that in this area map units are too heterogeneous to accept the suitability classification as being completely reliable. However, alternative procedures using methods of optimal interpolation to map gradual change within the physiographic units are too expensive at a mapping scale of 1:25000 or smaller. It is not possible to produce completely accurate suitability maps at smaller scales. However, incorporating nested sampling and analysis of variance as standard procedures in land evaluation surveys costs little effort and yields at least an estimate of map accuracy and reliability of the suitability classification.

Notes: Abstract. The ultimate goal of resource monitoring is to analyse the spatial distribution of the balance between supply and demand of a certain resource. Remote sensing techniques are commonly used for the assessment of the supply of resources. By integrating remote sensing with the related techniques of geographical information systems and spatial modelling, the demand as well as the accessibility of resources can be analysed. The article gives an overview over methods for integrated resource monitoring. Examples from arid environments are also presented.

Notes: Abstract. Since 1981 information on land sales has been recorded in the Land Register for some counties in Scotland. Rural land sale data for areas of more than 10 hectares in Renfrewshire have been analysed to determine the extent to which land capability, elevation and slope have an influence on land value. Although many factors influence the price paid for rural land, the effect of land capability in particular is demonstrated, with altitude having a minor effect. Using a best fit curvilinear model price ranges are predicted on the basis of land capability classes.

Notes: Abstract. Experiments on the effects of stockpiling soil on an opencast coal mine in Derbyshire showed that there were significant changes in the microbial community. Numbers of aerobic bacteria in stored soils ranged from 0.5 to 12.8 ± 107 colony-forming-units (CFU)g-1 with the smallest values being in the deepest parts of the oldest stores, whereas an adjacent undisturbed soil contained 6.6 ± 107 CFU g-1. There was a greater effect on the numbers of fungal spores, which ranged from 0.1 to 6.7 ± 105 CFU g-1 soil, all less than the 10 ± 105 CFU g-1 recorded for the undisturbed control soil. The number of fungal spores in the deepest part of the older soil stores was only 1/100 of the number in the undisturbed soil. This was mirrored by the biomass values, as determined by adenosine triphosphate (ATP) assay. Values of ATP ranged from 0.38 to 13.13 nmol g-1 as compared to 5.8 nmol g-1 in the undisturbed soil. All three of these microbiological properties decreased in value with both age and depth of storage. Neither anaerobic nor spore-forming bacterial numbers were greatly affected by storage.The pH values tended toward neutrality in the deeper parts of the soil stores, and there was less organic matter in the older stores.

Notes: Abstract. Increasing the ploughing depth and ploughing in grassland has been common in Germany during the past 20 years. Incubation studies were conducted with topsoils from luvisols and gleysols at different times after change of management in order to assess its influence on nitrogen mineralization and its kinetic parameters.The results show that deep ploughing slows the mineralization of nitrogen. The difference between earlier (1967–72) and more recently (1980–82) deepened topsoil has become smaller after a further three years of cultivation, however. The preceding crops (wheat or sugar beet), the amount of N fertilizer as well as clay and nitrogen contents cause a variation in N mineralization. The results indicate a continuing approach of an‘equilibrium’organic matter and nitrogen content. The enrichment capacity of intensively managed soils may be replenished within 10 years.Gleysols formerly under grass mineralize more nitrogen than‘traditionally’ploughed soils, even 27 years after the ploughing-in. While nitrogen from easily decomposable materials decreases within the first 10 years, the resistant fraction is a long-lasting determinant for N mineralization. Both processes need to be considered when applying fertilizer to minimize nitrate leaching.

Notes: Abstract. A number of restored areas, a soil store and undisturbed areas on opencast coal mine sites, all of similar soil type, were sampled. The microbiological activity (dehydrogenase assay), nitrogen mineralization and nitrifying potentials and physico-chemical characteristics of the soils were determined. Dehydrogenase activities ranged from 140 to 580 μg TPF g-1 24 h-1 in undisturbed control soils, whereas the disturbed soils had activities of 10 to 220 μg g-1 24 h-1, with the smallest activities being recorded in the stored and most recently reinstated soil, indicating that disturbance has depressed microbial activity. Nitrogen mineralization potential was significantly affected by disturbance, with a value of 18 to 26 μg inorganic N g-1 21 d-1 in the soil store and 38 μg-1 21 d-1 in a soil reinstated for six months, although the values were less than this in soils reinstated for up to six years. Nitrifying potential was not significantly less in the stored soils, being within the range of 60 to 135 μg nitrate N formed g-1 soil 21 d-1, which was similar to that found in the undisturbed control soil.The water-holding capacity was less in the stored soil than the undisturbed controls, and was significantly less in soil reinstated for 1.5 to 2.5 years, being only 65% of the undisturbed value (0.66 g water g-1 soil). Ammonium content of the soil store was one hundred fold larger in the soil store than in the controls (0.6 to 1.7 μg ammonium N g-1). The carbon contents in the control soils ranged from 4.5 to 7.2%, whereas the stored and reinstated soils had generally less amounts ranging from 1.6 to 5.8%. There was a significant and positive correlation between water-holding capacity and nitrifying potential.The implications for long-term restoration are discussed.

Notes: Abstract. Water samples from ditches draining small upland areas in mid-Wales were collected before, during and after the improvement of the pasture using two different cultivation techniques. The samples were analysed for nitrogen, phosphorus, potassium and pH. The greatest release was associated with disc harrowing where nitrogen, in its nitrate form, exceeded European Economic Community maximum recommended concentrations for potable water supply for two weeks. Smaller losses of nitrogen, in the ammonium form, and of ortho-phosphate were observed following a minimum cultivation technique. It is concluded that, on a scale normally associated with upland Britain, pasture improvement is not likely to deteriorate significantly the quality of runoff within water supply catchments. This is confirmed by the results obtained from monitoring streamflow from catchments in which some degree of pasture improvement had been undertaken in the past.

Notes: Abstract. Direct drilling was compared with mouldboard ploughing on a sandy clay loam using winter wheat as the test crop for a period of four years (1978/79 to 1981/82). The effect of short- and long-term sequences of direct-drilling on grain yield from 1981/85 was also investigated and in 1983/84 and 1984/85 the effect of soil loosening by a slant-legged subsoiler, the‘Paraplow'. The range in annual mean yields was 7.19 to 9.32 t ha-1. There were no significant differences in grain yield between direct-drilling and ploughing except in 1979 when direct-drilled wheat yielded 0.60 t ha-1 more than wheat after ploughing. The number of years the land had been direct-drilled had no effect on grain yield.Using a slant-legged subsoiler on direct-drilled land significantly reduced cone resistance and increased root density, but these effects were variable across the working width of the implement. Subsoiling did not increase yield in 1983/84, and in 1984/85 it reduced yield by 0.45 t ha-1.Long-term direct drilling of winter wheat on the Tickenham soil series is unlikely to result in a loss of yield provided straw is burnt and grass weeds are controlled.

Notes: Abstract. Changes in aggregate stability, density, and porosity as well as the water retention and nutrient contents of different aggregate size fractions due to intensive tillage were investigated. Three soils from Vicarello, Fagna and Gambassi in North Central Italy which had been under permanent vegetation, minimum or conventional tillage for more than seven years were studied. The aggregates on conventionally tilled plots were slightly denser and less porous than those on the untilled or minimum-tilled plots. The aggregates were less stable under conventional tillage on all soils. Conventional tillage reduced the proportion or macro-aggregates by 22% at Vicarello and 35% at Gambassi. There were no differences in macro-aggregate proportions between minimum- and conventionally tilled plots at Fagna. The potential of the dry aggregates to distintegrate upon contact with water was greatest in the conventionally tilled and least in the untilled treatments. The proportions of dry macro-aggregates (〉 0.25 mm) in the untilled and tilled plots were 90 and 71%, respectively. The soil of the tilled plots contained less carbon and nitrogen than that of the untilled plots in all aggregate size fractions. The silt-plus-clay contents of the aggregates accounted for between 65 and 93% of variability in the water they retained at small potentials while organic carbon contents accounted for between 71 and 90% of variability in the stability of the aggregates irrespective of the tillage treatments.

Notes: Abstract. Between 1981 and 1987 field experiments were made on loam and sandy loam soils to test the effects of nitrogen, phosphorus and sulphur fertilizers on the yield and quality of linseed, and the uptake of S by the crop. In one experiment, all through the six years, the application of fertilizers up to 60 kg N, 40 kg P2O5 and 30 kg S ha-1 increased yields. In the second experiment, the same combination of N, P and S maximized crop yield, uptake of P and S, % oil and oil production. These balanced and optimum rates of fertilizers decreased the percentage of stearic, oleic and linoleic acids but increased that of linolenic acid by accelerating the metabolic pathway of linolenic acid synthesis. Applying P decreased the removal of native S in the soil but when more S was applied, more native S was taken up. Large dressings of P diminished crop yield and quality as well as the availability of native soil S.

Notes: Soil Management. A Practical Guide to the Use and Management of Soils. By T. Batey.

Notes: Abstract. The topsoil widely bought and sold for landscaping and similar schemes is intended to cover poor substrates and to provide improved growing conditions for plants. Two extensive surveys have shown that top soils at present being used are of very poor quality and rarely meet this requirement. Many of the substrates that the topsoils cover out-perform them, or can readily be improved to do so if modern land reclamation techniques are used.From this it follows that there could, and should, be (i) much more discretion in the use of topsoil, (ii) more attention paid to the improvement of existing substrates, (iii) more consideration given to the use of other materials as topsoil substitutes, and (iv) more care taken in the choice of top soil materials where these have to be used.It is suggested that the present British Standard for topsoil is inadequate and that is should be replaced by a three-tier system in which there would be separate specifications for; (i) high grade topsoil, (ii) lower grade topsoil, (iii) materials which can act as topsoil substitutes. In this way it should be possible to obtain a better and more reliable performance in landscaping schemes and lower costs.

Notes: Abstract. The performances of 16 different sand and sand-soil root zone constructions were examined during three seasons of simulated football-type wear. Water infiltration rates were controlled mainly by the percentage of sand in the rooting matrix although the type of sand also had a strong effect in the pure sand root zones. Even mixes with 91% sand had poor infiltration after two seasons of wear and suffered from occasional ponding after heavy rain. Pure sand root zones and high-specification sand-soil mixes had better grass retention and a firmer surface in wet weather than root zone material with sand contents 〈 90%. Traction values for the different root zone materials were similar, except for a pure sand construction based on a coarse 0.25–1.0 mm diameter sand. However, pure sand constructions can become unstable, particularly in dry conditions if the ground cover is less than 20%. Strategies for the use of sand amelioration and pure sand root zones are discussed in relation to the demands of particular user groups.

Notes: Abstract. Fertilizer application to sports turf has a significant effect on the playing characteristics of the surface as well as its aesthetic appearance. Nutrient availability affects leaf and root density, infestation by weed species, resistance to fungal pathogens, tolerance to wear, drought and cold in the turf grasses and surface hardness. The increasing use of high sand content, free-draining root zones for sports areas is leading to a larger demand for nitrogen and also to an increased interest in the use of slow-release nitrogen fertilizers. The optimum nutrient application rates are examined, particularly for nitrogen and the direction in which research on fertilization practice should take is considered.

Notes: Abstract. Techniques for restoring mineral workings to agriculture, forestry or amenity uses are described. An integrated scheme of working and restoration is vital, taking account of the soil resources available, appropriate methods of soil handling (usually by earthscraper or dump-truck and excavator) and a programme of aftercare including underdrainage. Changes in soil during storage are discussed. Some of the potential problems where the site is infilled with imported wastes are reviewed. The success of restoration can be judged by comparisons of soil properties, crop performance or the general acceptability of the restored site to the local residents.

Notes: Abstract. Graphs of soil pH against time were plotted for the Park Grass Experiment at Rothamsted Experimental Station, begun in 1856, and the Long-term Liming Experiments at Rothamsted and Woburn farms, begun in 1962. These showed that the magnitude and duration of the effect of lime applications varied with soil type, initial pH, fertilizer nitrogen application, and the crop grown. Simple equations for each situation were linked to form an empirical model which, with appropriate input data for soil type, crop, and initial and target pH, predicted the lime needed to reach that pH. Model predictions compared well with estimates from a Woodruff-type buffer method. The model forms a sound basis for a more comprehensive lime requirement model covering the whole of the United Kingdom.

Notes: Abstract. A spoil and vegetation survey was conducted of five fields reclaimed from coal mine spoils seeded in different years at the Whitewood mines of south-central Alberta, Canada. It aimed to understand the causes of visibly wide variations in ground cover of the seeded species which was mainly alfalfa. Sites were initially stratified into productivity classes: A (high), B (medium), and C (low) based on the seeded species, and then sampled. Cover and dry weight declined linearly with age of reclaimed field. The spoil at class-A sites contained more clay than that of class-C sites. It also contained more moisture and a better cover. Electrical conductivity (EC) and the concentrations of soluble B, Mg, Na, and K in the spoil were significantly greater at class-C sites. Cover and dry weight of the seeded species were negatively correlated with EC, B, Mg, and Na in the spoil, thus implicating these factors in poor vegetative productivity, particularly in the dry conditions that typify this part of Alberta.

Notes: Abstract. The measurement of the shear strength of the root plate/soil interface beneath mature trees is described. Results from this method are given for a total of 77 sample trees from crops of Sitka spruce aged between 24 and 35 years growing on a peaty gley, a deep peat and a brown earth. Shear strength was much higher for the brown earth than for either the peaty gley or the deep peat, mainly because there was a less clear-cut boundary to the rooting depth compared with the rooting boundary caused by the high water table on the peat sites. There was a slightly higher shear strength for the peaty gley than for the deep peat, but no apparent difference in shear strength between the peat and the underlying mineral soil in the peaty gley. The shear strength measurements were consistent with observed differences in tree stability and the method of measuring shear strength aids the assessment of susceptibility of trees to windthrow.

Notes: Abstract. The soil conditions both before and after restoring opencast sites and their effect on drainage and crop growth are discussed both in general and with specific reference to the site concerned. Both drainage treatments showed a benefit over the undrained control, although no extra benefit was observed from drains at 20-m spacing with mole drains and subsoiling compared to drains at 40-m spacing with mole drains. Subsoiling reduced bulk density and increased surface infiltration rates, but improvements to the soil brought about by subsoiling were short-lived.

Notes: Abstract. Comparisons of crop production on recently reinstated soil in Northumberland have shown that the reduced yield potential of such soil may not be inevitable. Storage of soil in bunds did not greatly reduce subsequent crop yields, but failure to drain the land did. Provided an effective drainage scheme was installed, arable and grass crops could be grown successfully, responding very well to additions of nitrogen fertilizer and other normal good husbandry practices. To date it seems that neither deep cultivation nor the use of grass leys were as effective in the restoration process as had been expected.

Notes: Abstract. Regression is frequently abused in soil research. Its proper use is for statistical prediction. It may also be used to calculate equations for calibration. A regression equation may be used to express a functional relation between two soil variables that are thought to be related by some simple mathematieal law but only where one of the variables is known exactly. In most other circumstances regression is inappropriate. Where departures from a functional relation are due to errors of measurement and sampling fluctuation it should be replaced by a structural analysis to find the best equation. Where the underlying relation is truly bivariate it should be described as such.

Notes: Abstract. Following removal of the upper 40 cm of soil, the physical properties of the exposed B horizon of a red-brown earth (Goulburn clay loam) were ameliorated using a combination of gypsum (5.4 ha−1) and rye grass. Phosphorus (P), nitrogen (N) and potassium (K) fertilizers were added to improve nutrient availability. The ameliorated properties of the exposed B horizon were compared with those of equivalent depths from an adjacent intact profile of Goulburn clay loam.Initially, during the establishment phase of the rye grass, the gypsum increased the electrolyte concentration in the 0–10 cm layer, and stabilized the soil surface against mechanical dispersion. After 18 months all the gypsum in the 0–10 cm layer had dissolved. However, in the presence of rye grass, the soil surface was no longer susceptible to dispersion by the mechanical impact of water. The rye grass improved soil physical properties mainly in the upper 20 cm of the exposed B horizon. Water-stable aggregation 〉 2000 μm and macroporosity increased, and bulk density and penetrometer resistance of the soil decreased.Continuous applications of P, N and K fertilizers resulted in a gradual improvement in the nutritional properties of the exposed B horizon. However, because of the large phosphorus adsorption by the exposed clay, 300 kg P ha−1 was required to provide sufficient available phosphorus in the 0–10 cm layer.

Notes: Abstract. This paper reviews research on sediment yields in British fresh waters affected by afforestation in their catchments. Soil erosion and sedimentation in fresh waters increase after afforestation in the uplands. In the long term a three-to tour-fold increase appears to be common in established upland forests, but much larger increases, some amounting to 50 times that before afforestation, have been recorded soon after ploughing, draining, roadmaking and harvesting. Some of the erosion has been exacerbated by environmental conditions such as steep slopes and storms. Improved silvicultural practices should reduce sediment output to fresh waters, but they might not prevent serious sedimentation following afforestation in the uplands. In contrast, afforestation of arable land under the Farm Woodland Scheme should result in decreased rates of erosion in the lowlands.

Notes: Abstract. The soil of amenity areas is important in the urban landscape. Some is natural, some is man-made. Both contribute greatly to the environment of our cities through the grass, shrubs and trees which they support. Results of research from agriculture and urban gardens have been extrapolated in this review to consider the significance of toxic metals in amenity soil. The metals of most concern for plant growth are zinc, copper and nickel as they are phytotoxic, but additionally lead, cadmium, arsenic, and mercury are of concern due to their effects on human health. The currently acceptable threshold values for metals in the soil of public open spaces, playing fields and parks are presented, and consideration is given to the toxic metal content of an assortment of materials likely to be used in constructing amenity soil.

Notes: Abstract. Assuming that there is no major chemical toxicity or deficiency, the major limitation in man-made soil is the loss of its natural structure, which, in turn, controls the air-water balance. Where such a soil has 〈 70% sand content this loss may adversely affect potential for use.Examples of man-made soils - sports turf and replaced opencast coal mining land - are used to illustrate principles of management. Two strategies exist: to encourage earthworms, thereby promoting effective site drainage by infiltration or, to limit their activity and rely mainly on surface shed. The implications of each of these soil options for wider management and use are discussed.

Notes: Abstract. Nitrogen deficiency is the major problem in the creation of new ecosystems on most derelict land. Initially there is insufficient nitrogen in the wastes to drive the new systems, and nitrogen accumulation is, therefore, required. The most cost-effective way of providing this nitrogen is to use leguminous species which fix nitrogen from the atmosphere. Once nitrogen starts to accumulate in the soil management should aim to promote efficient cycling. Maintaining a near-neutral soil pH and a sward with a small C:N ratio helps to increase the mineralization of nitrogen in dead plant residues, and grazing animals also reduce nitrogen accumulation in dead vegetation.

Notes: Abstract. Land evaluation involves the definition of the comparative marginal value of individual land areas for the uses being considered. For agricultural land evaluation crop yields are the most reliable estimates of comparative marginal values. Yield values can be obtained from field measurements, as well as from productivity indices and empirical and mechanistic crop growth models. This paper reviews the pros and cons of each approach. Mechanistic models of the summary type, that simulate only those processes that are critical to describe an agroecosystem, are the most realistic and practical tools for land evaluation. Criteria for these types of models are given.

Notes: Abstract. Good land management needs information about land resources and the processes taking place in the landscape. In practical land evaluation this information is often expressed in terms of land qualities. The original survey data are stored in geographical information systems where they can be used to estimate the values of appropriate land qualities. Land qualities are complex attributes of land used in planning that may be derived from the original attributes through empirical threshold or regression models, or from process-based deterministic or stochastic simulation models. In order to improve estimates of the distribution of land qualities in space and time, and hence to improve planning decisions, the models require data with a much better spatial resolution than is usually available. The problems and dangers associated with the ad hoc linkage of simulation models and GIS are discussed. Particular attention needs to be paid to the problems of error propagation and costs and benefits when using models.

Notes: A randomized-block experiment was carried out to evaluate a bacterial inoculant, based on a single strain of the organism Lactobacillus plantarum, as a silage additive. The inoculant-treated silage was compared with untreated and formic acid-treated silages. The three silages were harvested from a perennial ryegrass sward on 30 September and 1 October, 1985 using two double-chop forage harvesters. Formic acid (850 g kg−1) was applied at a rate of 31t−1 and the inoculant at a rate of 3 g mixed in 31 water t−1 (1 × 106 colony forming units (g grass)−1). The dry matter and water-soluble carbohydrate contents of the grass at ensiling were 165 g kg−1 and 18·9 g kg−1 respectively. For a period of 84 d, the three silages were offered ad libitum and supplemented with three concentrates in a 3 × 3 factorial design to 63 male cattle which were initially 15 weeks old and 128 kg live weight. The three concentrates were (1) barley (115 g crude protein (CP) (kg DM)−1), (2) barley/soyabean meal (207 g CP (kg DM)−1) and (3) barley/fish meal (200 g CP (kg DM)−1); each was offered at a mean rate of 1·7 kg d−1. For the untreated, formic acid-treated and inoculant-treated silages respectively, ammonia-N concentrations were 162, 91 and 176±60 g (kg total N)−1; pH's were 4·48, 3·89 and 4·45±0·046; butyric acid contents were 12·1, 1·3and 16·6g(kg DM)−1; metabolizable energy contents were 12·4, 12·2 and 1·23±0·29 MJ (kg DM)−1; silage DM intakes were 2·28, 2·49 and 2·44±0·037 kg d−1 and liveweight gains were 0·90, 0·95 and 0·97±0·023 kg d−1. For the barley, barley/soyabean meal and barley/fishmeal supplements respectively, silage DM intakes were 2·29, 2·43 and 2·49 ± 0·037 kg d−1 and liveweight gains were 0·87,0·97 and 0·99 ±0·023 kg d−1. There were no significant interactions between silage type and the supplement offered. It is concluded that silage fermentation and metabolizable energy contents were similar for the untreated and inoculant-treated silages but that silage dry matter intake and liveweight gain were significantly greater for the inoculant-treated than for the untreated silage. Further work is needed to elucidate the mode of action of this type of silage additive.

Notes: The seasonal patterns of dry-matter (DM) production by swards of Norwegian grasses originating from high latitudes 〉61°N (Dactylis glomerata Hattfjelldal, Phleum pratense Engmo and Poa pratensis Leikra) were compared over 2 years (1986 and 1987) with those of grasses developed at lower latitudes, 52°N (Dactylis glomerata Cambria, Phleum pratense Motim and Lolium perenne Perma) at a lowland site in southwest Scotland (55.5°N, altitude 45 m). In each year, there was a significant enhancement of the DM production of the high-latitude varieties of Dactylis glomerata, Phleum pratense and Poa pratensis at harvests during May and June, although the lower latitude grasses gave a higher proportion of annual production than the Norwegian grasses in April and from September onwards. These findings are compatible with the observed stimulation of DM production of high-latitude grasses by daylength extension under controlled conditions. However, since the stimulation of DM production did not occur until the normal peak of production in May and June, it served to accentuate the skewed distribution of production in Scotland, rather than to improve production earlier in the season. Since the total annual DM production was significantly lower for the high-latitude grasses in general at the lowland site, there does not appear to be a clear role for these grasses in UK agriculture.

Notes: Potential lamb production from grass-clover (75–80 kg N ha−1) swards was compared with that from grass-only (160–200 kg N ha−1) swards from 1985 to 1987 at the Bronydd Mawr Research Centre in mid-Wales. Separate pastures of three perennial ryegrass (Lolium perenne L.) varieties; Aurora (very early-flowering diploid), Meltra (late-flowering tetraploid) and Aberystwyth S23 (late-flowering diploid), with and without Aberystwyth S184 small-leaved white clover (Trifolium repens L.), were continuously stocked with Beulah Speckled Face ewes and their Suffolk cross lambs from spring (late April) until weaning in mid-July. From late July the pastures were grazed with weaned lambs until early November.Individual lamb liveweight gain was 8% more (P 〈 0·001) pre-weaning on grass-clover than on grass-only swards and 30% more (p 〈 0·001) post-weaning. Averaged over three years, mean stocking rate was 17% higher (p 〈 0·001) pre-weaning and 29% higher (p 〈 0·001) post-weaning on the grass-only pastures. Even so, total lamb output (kg ha−1) was similar from the two sward types, although during the pre-weaning period lamb production was 9% higher (P 〈 0·05) from grass-only swards.The results show the potential of grass-clover (low N) swards to improve the efficiency of lamb production from grassland since better individual lamb growth rate compensated for the lower stock-carrying capacity. That is, similar output was achieved with lower cost of fertilizer N input and with the lower costs associated with carrying fewer animals.

Notes: The productivity of fourteen grasses was measured under a silage cutting regime of four harvests per year for 3 years (1984-86) with an annual fertilizer N rate of 360 kg ha−1, applied at 120, 100, 80 and 60 kg ha−1 for successive harvests. The grasses were: red fescue (Festuca rubra)cvs Reptans, Dawson and Ruby, perennial ryegrass (Lolium perenne)cvs Perma and Sprinter, Yorkshire Fog (Holcus lanatus)commercial types I and II, smooth meadow-grass (Poa pratensis)cvs Parade and Arena, creeping bentgrass {Agrostis stolonifera)cv. Penncross, crested dogstail {Cynosurus cristatus)cv. Southlands and rough meadow-grass (Poa trivialis)cvs Dasas, Omega Øtofte and Sabre.Red fescue gave the highest dry-matter (DM) production over the 3 years but because of low organic matter digestibility (OMD), its production of digestible organic matter (DOM) was lower than that of perennial ryegrass. Rough meadow-grass was relatively low yielding in the first year and did not persist thereafter. Three-year mean DM production ranged from 9-22 kg ha”’(crested dogstail) to 14-37 kg ha-1 (red fescue cv. Reptans), while mean annual OMD values ranged from 0-660 (smooth meadow grass cv. Arena) to 0766 (ryegrass cv. Sprinter). The mineral composition (P, K, Ca and Mg) differed among species; creeping bentgrass, crested dogstail, perennial ryegrass and Yorkshire fog had moderate to high mineral concentrations while smooth meadow-grass had low concentrations. Mean two-year (1985-86) mineral composition (g kgDM−1) ranged from 3-1 to 40 (P), 234 to 31-0 (K), 3-8 to 6-0 (Ca) and 1-6 to 2-6 (Mg),It was concluded that while red fescue and Yorkshire fog showed considerable potential for silage DM production, there is scope for breeding red fescue cultivars with improved digestibility and more winterhardy Yorkshire fog; characterization of their ensiling qualities would also be useful.

Notes: Herbage and faeces samples were retained from an intake and in vivodigestibility trial using material harvested at three different stages from five indigenous hill plant communities (those dominated by Agrostis-Festuca., Nardus stricta., Molinia caerulea., Eriophorum vaginatum and Tri-chophorum caespitosum) and from sown swards of ryegrass or white clover. Samples of the herbages and of their separate components, together with extrusa samples of the same herbages recovered from pen-fed sheep and cattle oesophageal fistulates, were digested in vitrousing rumen liquor. Measurements were made also of faecal nitrogen concentration (FN) and of indigestible acid-detergent fibre (IADF) using the samples from the original trial.The range of in vitrodisappearance values of the herbages (IVOMD; 0809-0278) was slightly wider than those of in vivodigestibility (OMD; 0-796-0-37I). Differences between OMD and IVOMD were greatest at low quality and relationships were best described by two separate linear regressions of OMD on IVOMD for (a) ryegrass, white clover, Agrostis-Festucaand Nardus(RSD; 0 0185) and, (b) Molinia, Tricho-phorumand Eriophorum(RSD; 00246). In vitrodisappearance values of extrusa were higher than those of herbages offered by 00503 and 00156 units for sheep and cattle respectively, partly because of greater levels of ensalivation, especially in the sheep. The relationships of OMD to IADF and to FN were poor, though inclusion of faeces output and fitting parallel lines for communities in the regression of OMD on FN reduced the RSD to 0020. We conclude that in vitrodigestion of samples of extrusa, using appropriate standards, is the best method of diet digestibility prediction for sheep and cattle grazing these communities.

Notes: The use of irradiation as a means of preserving fresh forage for subsequent botanical and chemical analysis was examined as a possible alternative to preservation by freezing. Forage samples containing a mixture of grass species were given irradiation doses of either 2-5 Mrad (25 k Grays) or 5-0 Mrad (50 k Grays). These samples were then stored in the dark under either ambient or chill (+ 2°C) conditions for up to 5 months, while similar samples of fresh forage were stored over the same period deep frozen at — 15°C. No spoilage or signs of any subsequent senescence were observed in the forage given the 5-0 Mrad irradiation treatment during the 5 month storage period. In the 2-5 Mrad treated material some browning of lamina tips occurred. However, the irradiation treatment did cause some colour changes, mainly a darkening of the green tissue. The state of preservation was also assessed by measuring the rate at which stored herbage could be separated into the constituent species. No difference in separation rates was found between samples that had either been stored frozen or irradiated at 5-0 Mrad (and then stored under either ambient or chill conditions); however, separation rates were slower on the 2-5 Mrad treated samples. The irradiation treatment did not cause any significant change in percent nitrogen content. However, water-soluble carbohydrate contents in the irradiated samples were significantly lower. The cost of commercial irradiation treatment was less than 20% of the commercial cost of freezing and cold storage.

Notes: Experimental trials in both rainfed and irrigated conditions were carried out in Central Spain with the aim of assessing the best time to harvest whole-crop winter field beans for forage. Three times of harvesting during the pod-filling phase were considered: seed with less than 20% DM (L,), 30-35% (L:) and over 85% (Lj). At the early pod-setting stage (Lj), the stems and leaves represented 75% of the total aerial biomass. At pod maturity (L3), this percentage was reduced to 27%. Over the same period, Lj to L3, the seed's contribution rose from 8% to 59%. Chemical composition of the different plant components varied markedly during the pod-filling phase. Lignin in leaves and pod-shells rose abruptly from 082 and 090% DM at L, to 7-82 and 7-01 % DM in L3. Crude protein of the seed varied only slightly between harvests. Mean DM yields over both years of 3 44 ± 0-46. 607 + 071 and 428 ± 037 tDM ha‘ were obtained for the whole plants in rainfed conditions at the L1, L2 and L3 stages respectively. Corresponding values for irrigated conditions were 552 +0-7I, 8-66± M 6 and 684±082 tDM ha“'. Taking into account the chemical composition of the whole plant at the three times of harvesting (mean values in both conditions of 675, 657 and 641 g I00gDM-’for DDM and 215, 18 7 and 186% DM for CP), it is concluded that the highest estimated energy and protein yields would be obtained by harvesting the plant at the Li stage (seeds with 30-35% DM).

Notes: Field trials were conducted in 1985 and 1986 to assess the effects of the growth regulator RSW0411 on a Lolium perenne L. (perennial ryegrass) seed crop. Applications were made at spikelet and floret initiation, and at 1, 2, 3 and 4 kg active ingredient ha−1.Seed yield increases in 1985 were associated with increased reproductive tiller numbers and seed numbers, but in 1986 there were no seed yield responses.Lodging was less severe in 1986, and there was less secondary filtering during seed maturation. In 1985, fertile tiller numbers were lower in control plots at harvest. These results are discussed in relation to the seasonal disparity in seed yield response.RSW0411 application significantly decreased culm lengths by shortening the basal internodes, and this effect was greater with higher application rates. Stem width was increased in 1985 at the base and middle of the stem, and earlier applications increased the basal width by more than later applications.Germination was not affected by RSW0411 treatment, except when applied at 4 kg active ingredient ha−1 in 1985, when there was a small decrease. This was related to a low 1000-seed weight, and is discussed in relation to seed maturity at harvest.

Notes: Three contrasting white clover varieties, Olwen (large-leaved), Menna (medium-leaved) and S184 (small-leaved) were sown with and without a grass companion in 30 cm drills. Two grazing and one mechanical spring defoliation managements were imposed. Counts of the total number of inflorescences and of the percentage in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Inflorescence numbers were greatest in cv. S184 and least in cv. Olwen and, in general, varieties produced both more inflorescences and a greater proportion of ripe inflorescences when grown under spring defoliation managements similar to those for which they were bred. Thus, cv. Olwen produced more ripe inflorescences, and a lower proportion of brown inflorescences (semi-ripe), after mechanical defoliation while cv. Menna produced more ripe inflorescences following mechanical defoliation and rotational grazing. However, cv. S184 produced more ripe inflorescences under both grazing managements than under mechanical defoliation. Optimum harvest date was not affected by management or variety, total inflorescence number and maximum ripe inflorescences having reached a peak on 11 September. However, varieties differed in the proportion of ripe and brown (semi-ripe) inflorescences on this date, with cv. Menna and cv. S184 containing a significantly higher proportion of brown inflorescences than cv. Olwen, The implications of these differences in inflorescence development, the proportions of inflorescences in the various ripeness categories and their contribution to seed yield are discussed in relation to the management of white clover seed crops and harvesting method under UK climatic conditions.

Notes: Herbage (83%Lolium perenne and 17%Trifolium repens) was harvested 15,28 and 42 d after second cut, and ensiled in 1.5 liter preserving jars either directly, at 20% dry matter (DM), or wilted (30 and 45% DM). Each variant was ensiled with and without a commercial preparation of cell wall degrading enzymes and stored for 90 d at 30°C. Samples were then incubated in nylon bags in the rumens of three cannulated cows for 3, 6, 12, 24, 48 and 288 h to study the in sacco degradation of organic matter (OM), crude protein (CP), and (hemi) cellulose.Addition of cell wall degrading enzymes significantly decreased cell wall content. The magnitude Of the decrease was influenced by stage of maturity and DM percentage. Maturity increased the DM content as well as decreasing the effect of enzymes on cell wall components. Lactic acid content increased and the pH value and ammonia (P 〈 0.05) decreased, indicating a greater extent of fermentation in the enzyme-treated silages. Enzyme treatment had no effect on the content of digestible OM estimated by in vitro incubations.The undegradable fractions of OM, CP and cell wall components were not significantly changed by the addition of enzymes. The results suggest that the cell wall degrading enzymes affected the insoluble, rumen-degradable fractions, thereby increasing the instantly degradable fractions. Consequently, the calculated effective degradation of OM and CP in the enzyme-treated silages was significantly (P 〈 0.05) higher than in the untreated silages.

Notes: The performance of prairie grass (Bromus willdenowii Kunth) cv. Grasslands Matua was examined under mowing at five defoliation intervals (10, 20, 30, 40 and 50 d) and two defoliation heights (3 cm and 8 cm). Annual and seasonal production of both the total herbage and of Matua, and the proportion of Matua in the sward, increased with less frequent defoliation. To a lesser extent, increasing the height of defoliation increased dry matter yield. Matua tiller numbers were increased by less frequent defoliation and were greater under the 8 cm than the 3 cm defoliation height. To increase prairie grass production and persistence, rest intervals between grazings of 40 to 50 d are recommended, or alternatively, a management involving silage or hay cutting offers scope.

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

Notes: Changes in the weight per unit length along the first and second fully-expanded laminae of Lolium perenne, Agrostis stolonifera, Holcus lanatus and Poa trivialis were experienced in tillers harvested in April and June 1987 from a permanent pasture under contrasting nitrogen treatments. Schematic models representing the weight distribution along the laminae of the different species are presented. From these models, predictions of the weight of any given proportion of the lamina length have been calculated. The weight of segments of lamina have been estimated, using the appropriate lamina model for a species, and these estimates provided consistently greater precision than estimates of lamina weight when no correction for lamina shape was considered, the length of a segment of lamina simply being multiplied by the mean overall weight per unit length of the lamina.

Notes: Water-soluble carbohydrate (WSC) contents of the early heading perennial ryegrass cultivar Aurora and five late heading cultivars were assessed in samples from 1 m × 2 m plots cut eight times in 1983 and five times in 1984. Despite fluctuations due to effects of the environment and plant development, the ranking of the cultivars in terms of WSC generally remained constant. Aurora had the highest overall WSC content. Majestic and Aberystwyth S23 had the lowest while Perma, Melle and Ba 9795 were intermediate. In the same trial, the ranking of the F2 hybrids between the late heading cultivars and Aurora was also consistent with that obtained previously in F1 and F2 spaced plants. Melle F2 families had the highest WSC followed by Perma F2, Ba 9795 F2, S23 F2 and finally Majestic F2 families. This ranking also remained constant over a generation of intense selection for uniformity of heading date. It was concluded that WSC is a consistent and heritable trait in breeding perennial ryegrass. Aurora was a good resource for improving WSC but the turf-type perennial ryegrass. Majestic, had a strong negative effect on WSC content in hybrid material.

Notes: Invertebrate numbers were studied in two white clover cultivars trials, grown with perennial ryegrass Weevils (Sitona spp.), slugs, lucerne flea, leatherjackets and as were more common (at least at some life stage) in cultivars of lower cyanogenic potential. Damage to clover foliage by the first three species was also negatively related to cyanogenesis. The production of HCN ranged from 0.025 mg to about 1.8 mg g−1 fresh leaf. There was no evidence of any other factor influencing cultivar preference.Cyanogenesis had most effect on numbers of weevil larvae and leatherjackets. The effect on weevil larvae was attributed partly to intercultivar differences in oviposition, but it was also suspected that larvae had fed on cyanogenic parts of the plant before reaching the root. Leatherjacket numbers developed inter-cultivar differences during larval growth. In one case these differences were detectable by December. By March in the second experiment there were approximately three times as many leatherjackets at the low as at the high end of the cyanogenic range. Approximately four times as many Sitona larvae were found at the lower as at the higher end of the scale. There was some evidence that a higher clover content in the sward was attractive to ovipositing Tipula paludosa but not in recently harvested cultivars of high cyanogenic potential

Notes: A farm-scale trial to compare the effectiveness of polythene bags and wrapping of big bale silage was monitored for Listeria monocytogenes contamination. There was no significant difference between the level of L. monocytogenes found in wrapped and bagged big bale silage, but the work confirmed that big bale silage is prone to contamination by Listeria organisms, and that the degree of Listeria contamination could be significantly reduced by the removal of obviously spoiled material prior to feeding.

Notes: A field experiment was established in May 1986 in which four white-clover populations originating in Switzerland, and a bred variety, Menna, were grown in binary mixtures with their ‘co-existing’ perennial ryegrasses and three other bred ryegrasses— Aurora, Talbot and Melle. The productivity of both components of the mixtures was measured by cutting samples in October 1986 (after establishment) and on five occasions during the growing season in 1987, Substantial differences were observed between clover yields in different mixtures, and the yield ranking of clover was found to vary with companion grass. It was concluded that the interaction between grass and clover populations originated at an early stage in sward development, being evident in both the 1986 establishment cut and the spring cut of the following year. The implications of these results for the formulation of breeding objectives and the evaluation of breeding material are briefly discussed.

Notes: Seeds of perennial ryegrass were sown by hand in micro-plots. Six treatment factors were applied, in all combinations, totalling thirty-two treatments. The factors were (a) firm vs light compaction of the seedbed, (b) 1 cm vs 2·5 cm sowing depth, (c) fertilizer applied to seedbed vs no fertilizer, (d) fungicides applied to the seed and seedbed vs no fungicide, (e) pesticide applied to seedbed vs no pesticide, and (f) soil kept moist after sowing vs soil kept dry after sowing. Overall, seedling emergence was increased by moist soil (18%), fungicides (16%) and by sowing at 1 cm depth (8%). In dry soil, fungicides increased emergence by 32% but had no effect in moist soil.In other experiments, micro-plots were sown at monthly intervals, from April to October. Seeds were either treated with benomyl + captan (3 g + 3 g a.i. (kg seed)−1) or not treated, and the plots were either covered to keep the soil dry, or uncovered. Seedling emergence on uncovered plots was increased significantly, by 16–28%, at the May, June, July and August sowings, when soil temperatures were at their highest and soil moisture contents at their lowest. On covered plots fungicides significantly increased emergence at the June sowing only, by 16%. The reasons for this anomaly are discussed.

Notes: The response of continuously stocked spring-calving beef cows and calves to a range of sward surface heights was determined. Mean sward heights of 4-5, 60, 70, 91 and 11-0 cm (treatments A to E respectively) were maintained from mid-May to mid-August (Period 1) and treatments C, D and E continued until the end of September (Period 2), during which time mean sward heights were 5-4, 7-8 and 9-2 cm respectively. Hereford x Friesian or White Shorthorn-x Galloway cows with their Charolais-cross calves were used, with 9, 6, 6, 5 and 9 cows on treatments A to E respectively. During Period 1 the mean live weight gains of cows were-0-52,-005,0-32,075 and 0 40 (s.e.d. 0167) kg d−1 on treatments A to E respectively and during Period 2.-0-31, 057 and 059 (s.e.d. 0153) kg d−1 for treatments C, D and E respectively with maximum cow liveweight gain at sward heights of 8 to 10 cm. Calf liveweight gains were 0 88,091, 098, 1 04 and 1-06 (s.e.d. 0068) kg d−1 in Period 1 for treatments A to E respectively and 098, 1-22 and 1 35 (s.e.d. 0067) kg d−1 in Period 2 for treatments C, D and E. The percentage of area infrequently grazed was generally less than 20% on treatments A to D, but on treatment E it was more than 40% for 6 weeks after turnout and thereafter remained between 20 and 40%. Maximum calf liveweight gain per hectare was achieved on the shorter swards, but maximum total liveweight gain of cows and calves per hectare occurred on treatment D. It is concluded that for maximum cow and calf performance on continuously stocked pastures, sward height should be maintained at no more than 8 cm in spring and early summer and then increased to 9 to 10 cm later in the grazing season.

Notes: A deterministic model that simulates forage dynamics is described and validation results presented. The model simulates different species of grasses and forbs for a production year and provides the necessary input for a diet selection model. The model does not simulate growth, but does simulate the accumulation of live leaf and stem, the senescence of live biomass, and its transfer to dead mass using growth rates for leaf and stem of each species, which are specified for the model. Using such an approach specific types of years can be simulated. Plant components in the model include live leaf and stem, dead leaf and stem, and old dead leaf and stem which were produced during the previous growing season. These plant components were chosen because of their importance in the diet selection process and their differences in forage quality. Plant species which the model was validated against were Cynodon dactylon, Avena sativa. Schizachyrium scoparium and Paspalum plicatulum. Validation results indicated that with adjustment to input growth rates, live biomass could be adequately simulated. Deviations between measured and simulated dead components were observed for S. scopariumand P. plicatulum.High values observed for dead stem early in the trial resulted from lack of separation of dead and old dead stem material in the field sampling. Variations in dead forage throughout the season were caused by unexplained sources of variation. This indicated a need for field research to better quantify the dynamics of dead biomass. The model meets its goal of simulating biomass dynamics and forage quality of plant parts and it provides a suitable forage base to interface with diet selection and animal simulation models.

Notes: Meteorological factors influencing the temporal changes of digestibility of grasses in spring and early summer are discussed. Annual observations in England of the digestibility of three grasses are then related to the relevant meteorological variables using two multiple regression analysis methods. The resulting regression relationships are tested on independent data, and finally sets of regression coefficients are recommended for predicting from synoptic meteorological data the weekly progress of digestibility in different areas of England: a simplified set of regression relationships for predicting digestibility values a few days ahead which require forecasts of only temperature in order to be applied operationally is also given.

Notes: Two 2×2 factorial experiments are described in which a bacterial inoculant being developed as a silage additive and containing a strain of Lacto-bacillus plantarum (Ecosyl, ICI plc) was evaluated at two harvests (18 July and 30 September 1985) of two swards (perennial ryegrass and permanent pasture) in difficult ensiling conditions. On each occasion erbage was ensiled with and without inoculant using two 0·5–t capacity steel tower silos per treatment. The contents of the two replicate silos per treatment were combined for feeding to cross-bred wethers in digestibility and metabolizable energy (ME) partition studies.Overall, inoculated herbage declined in pH post-harvest at a faster rate than control herbage (p〈0·001) and three out of the four inoculated silages had lower pH, ammonia-N, acetate and alcohol and higher residual soluble carbohydrate content (p〈0·001) than control. Significantly higher digestibility of nutrients (P〈0·05) was found in three of the inoculant-treated silages and these also had significantly higher ME values than control (P〈0·001), (10·58 and 8·77 MJ kg tol DM−1 for the treated and untreated silages respectively). The use of inoculant on herbage of only moderate ensiling potential therefore, produced significant improvements in fermentation quality and feeding value over control.

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

Notes: Populations of lactic acid bacteria (LAB) on lucerne before and after havesting were extensively monitored over a two-year period and correlated with weather data, various wilting parameters and equipment used for harvest. The LAB on standing lucerne were below detectable levels (〈10 colony forming units (CFU) g lucerne−1). Immediately after mowing, low levels of LAB (51 CFU g−1) were found on over half the samples. During wilting, the population of LAB generally increased. The amount of increase was affected primarily by the average air temperature during wilting, the length of wilting and the drying rate. The first two variables were positively correlated with bacterial growth whereas increased drying rate adversely affected LAB numbers. If the LAB numbers in the swath were below 100 CFU g−1 prior to chopping, the forage harvester inoculated the chopped lucerne an level of 102 to 104 CFU g−1, depending on air temperature. Considering these factors, LAB counts on chopped lucerne could be predicted within one order of magnitude approximately 95% of the time.

Notes: In a small-plot trial five grass varieties bromegrass cv. Grasslands Matua, perennial ryegrass CVS. Melle (diploid) and Bastion, Condesa and Meltra (tetraploid) were established as grass/white clover swards with white clover cv. Menna. Productivity was measured under 6-weekIy cutting both without N fertilizer (No) and with 100 kg N ha−1 applied in spring (N100) Evaluation was made over 2 harvest years, 1986–87.Total mean annual production of herbage dry matter (DM) in the first harvest year at No and No was 5·07 t ha−1 and 6·93 t ha−1 respectively. In year 2, corresponding values were 11·81 and 12·67 t ha−1. In year 1, Matua swards at No and N100 yielded 5·08 and 6·65 t DM ha−1 compared with 507 and 70 t DM ha−1 for the mean of the four ryegrass varieties. In year 2, corresponding values were 12·90 and 12·29 for Matua and 11·54 and 12·78 for the four ryegrasses. In year 1, the digestable organic matter in the dry matter (DOMD) of the Matua swards was lower than that of Melle, Bastion and Condesa at NO, particularly at the first cut. In year 2, differences in DOMD between treatments and varieties were not significant.The proportion of white clover was found to be higher in the No than the N100 treatment, and also higher in year 2 in most treatments. For the No treatment Matua swards had the highest proportion of white clover in year 1 (32% compared with 24% for the mean of the ryegrass varieties) but the lowest proportion in year 2 (27% compared with 60% for the ryegrasses). For the No treatment in year 1 clover production was also 43% higher, on average, from the tetraploid treatments than with Melle as the companion grass; for this comparison in year 2 the differences were not significant.It is concluded that Matua bromegrass/white clover swards receiving no N fertilizer may have a good potential under cutting management. However, the evidence from this trial is that in the second year the proportion of white clover is lower with Matua swards than with perennial ryegrass as the companion grass.

Notes: Progress in improving the feeding value (FV) of forage plants has been slow despite the benefits to animal production that can result from using plants of intrinsically higher FV. The slow progress is due in part to a lack of consensus on the criteria to be used in breeding or selecting forages of high FV. This paper reports the use of the Delphi technique to obtain such a consensus from an international panel of specialists in grazing animal production.The specialists, from Europe, USA, New Zealand and Australia, ranked eleven criteria for improving the FV of grasses and legumes for liveweight gain and for wool production.In general, the primary criteria chosen were high digestibility, easy communication, high nonstructural carbohydrate, high crude-protein and, for sheep kept primarily for wool production, a high sulphur-amino acid content. High relative palatability, high lipid-content and erect growth habit were ranked as least important. It was generally considered that mineral content and anti-quality constituents should be monitored rather than making them specific breeding objectives, although some exceptions were noted. Minor importance was attached to having ‘appropriate’ tannins in grasses; however, this was given a high priority in legumes. These criteria, and the desirability of reducing the extent of protein degradation in the rumen are discussed in relation to comments made by panel members.

Notes: The phosphorus (P) status of perennial ryegrass was measured using three tissue tests. The results were compared with dry matter (DM) production from ryegrass, and levels of extractable soil P, taken from a fertilized non-calcareous gley in a field experiment. Large errors were associated with the test values but it was possible to separate P deficiency from luxury uptake with tissue tests for total P and inorganic P (Pi) in leaves. The latter test is simple and merits further investigation.

Notes: Several experiments were performed in spring summer over the period 1982–85 to study the relationships between digestibility of energy (DE), gross energy intake (GEI), acid detergent fibre (ADF) and dry matter (DM) content in pasture.Wether sheep in metabolism pens and fed ad libitum with daily-cut fresh pasture were used. Two plots with different botanical composition were used to provide herbage; one dominated by Lolium perenne and the other by Holcus lanatus. A high correlation (r= -0·91) was observed between DE and ADF. The prediction used a second-order degree polynomial.Gross energy intake and digestibility of energy were scarcely correlated (r= 0·50) when all cases as a whole were considered. Higher correlations between GEI and DE (r= 0·69) were obtained when only data from pastures where Holcus lanatus prevailed were considered, and still higher (r= 0·91) in those pastures dominated by sown species with DE values lower than 70%.Herbage DM content had a large effect on GEI(r= 0·83) in the pastures dominated by perennial ryegrass with DE higher than 70%, the correlation between DE and GEI being low and negative (r=-0·36). It is possible, therefore, to predict apparent digestibility of pasture energy from ADF. However, DE is closely related to GEI only in those pastures in which DE is lower than 70%, DM content being an important factor limiting the intake of those fresh pastures dominated by Perennial ryegrass when DE is above 70%.

Notes: This study investigates forage particle breakdown, which is a factor of potential importance for the low intake of forages, particularly tropical grasses. A comparison was made between fresh leaf blades of a tropical grass, green panic (Panicum maximum var. trichoglume) and a temperate grass, Italian ryegrass (Lolium multiflorum). Leaf blades were chopped into 50 mm lengths and fed to cattle with oesophageal and rumen fistulae. Particle size was assessed on chewed samples immediately after eating and after digestion for 6, 12, 24, 48, 96 h and 3 weeks in nylon bags in the rumen.Chewing during eating reduced particle size more in length than in width and more in green panic than in ryegrass. Mean length was decreased 9·2-fold and 4·7-fold for the two species respectively, and mean width 5·4-fold and 2·3-fold. Green panic leaf had a higher cell wall content and higher dry matter content than ryegrass leaf.Digestion caused a substantial reduction in the width of the particles but not in the length. Width reduction occurred more rapidly in the ryegrass which was reduced to narrow fibres within 12–24 h of digestion while in green panic the same extent of degradation took 〈 48 h. After 96 h digestion, mean width of the chewed material had been reduced 40-fold in ryegrass compared with only 165-fold in green panic; all particles of both species were 〈 1 mm in diameter. The mean length of particles after 96 h digestion was similar to that of the chewed feed. Ryegrass was more digestible than green panic, a difference of 150 g kg DM−1 which was maintained from within the first 6 h of digestion up to 96 h digestion. After three weeks the digestibility of ryegrass was c. 50 g kg DM−1 higher than that of green panic but the proportion of cell wall that was ultimately indigestible was the same (0465) for both species.

Notes: Comparative chemical composition, in vitro digestibility, and in vitro volatile fatty acid (VFA) concentration and molar proportions of current year's growth of twelve important native New Mexico forage species were evaluated. Volatile fatty acid data were collected on forage samples subjected to 12-h in vitro digestion using two different inoculum sources. Forbs and shrubs had higher (P〈0·05) total nitrogen and total available- nitrogen concentrations than grasses; however available nitrogen as a percentage of total nitrogen did not differ (P〉0·05) among grasses forbs and shrubs. in vitro organic matter digestibility (IVOMD) was higher (PKOOS) for forbs and shrubs than grasses for all incubation periods (24, 48, 72 hours). Lucerne hay and prairie grass hay inocula gave similar IVOMD results. Based on 24-h IVOMD divided by 72-h IVOMD, forbs were digested more rapidly than grasses (P〈0·05). Total VFA concentration and molar proportion differences among grasses, forbs and shrubs were small

Notes: During an experiment in which the height of mixed perennial ryegrass/while clover swards was maintained throughout the season at 3 or 7 cm (S and T, respectively), or were maintained al those heights until 30 June then changed (ST and TS), a limited study was made of the effects on the population densities and masses of the two species. During the earlier part of the season the short swards (S and ST) developed higher tiller and stolon growing point (sgp) densities, but with a reduced mass of ryegrass, principally of the pseudostem fraction, than the tail swards (T and TS). Thiere was little effect of sward height on the mass of clover. Whilst there was a general tendency for tiller and sgp densities to increase during the latter part of the season, tiller density increased greatly where sward height was reduced (TS) and both tiller and sgp densities were reduced where sward height was allowed to increase (ST). Changing sward height, whilst limiting the accumulation of dead grass material (TS), allowed grass leaf and dead masses to increase (ST), and adversely affected the increase in the clover component, principally of stolon material, in both ST and TS.

Notes: The growth of Trifolium semipilosum Fres. var. glabrescens Gillet cultivar Safari, and Trifolium repens L., cultivars Haifa and Grasslands Huia was compared in controlled temperature glasshouses at 15/10, 21/16, 27/22 and 33/28°C (day/ night), and over eighteen months under four-weekly cutting in the field. In glasshouses, white clovers grew better than Safari at all temperatures except 27/22°C. Stolon production and partitioning of dry matter to stolons was greater, and petiole production and partitioning of dry matter to petioles was less for Safari than for white clovers. Haifa and Huia differed primarily in individual leaf weight, individual leaf area and leaf numbers; with Hula and Safari, but not Haifa, exhibiting a reduction in leaf size in response lo defoliation. In the field, growth of Safari was poor. Growth responses of Haifa and Huia in the field were related to seedling vigour, dry matter partitioning between leaves and stolons, and response to defoliation at low temperatures. It was concluded that there were major differences in growth, dry matter partitioning, morphology and response to temperature between T. semipilosum and T. repens. These differences particularly influence climate adaptation and competitive ability at the seedling stage.

Notes: Two 2×3 factorial design experiments were conducted during 1985 to compare the effect of treating grass at ensiling with a silage inoculant (Imperial Chemical Industries plc) or formic acid with an untreated control, on fermentation, in-silo losses, intake and performance of finishing cattle.In experiment 1, three covered concrete-walled silos were each filled with approximately 70 t of primary growth, unwilted herbage at each of two cutting dates, 20–21 May (early harvest) and 3 June 1985 (late harvest). In experiment 2, the above procedure was repeated for second regrowth grass with two cutting dates, 30 September-1 October (early harvest) and 16–21 October 1985 (late harvest). The water-soluble carbohydrate (WSC) contents of the herbage were low in both, being 130–160 and 121–137 g kg−1 DM for the first and second experiments respectively. In both experiments the formic acid-treated silages attained lower temperatures than the inoculant-treated and untreated silages. At both harvests in experiment 1 the pH, ammonia nitrogen (NH3N) and volatile fatty acid (VFA) contents of the inoculant-treated and formic acid-treated silages were significantly lower than those in the untreated silage. However, at the early harvest in experiment 2 the pH and NH3N contents of the inoculant-treated silage were significantly higher than those in the two other silages. At the late harvest in experiment 2 the inoculant-treated and the formic acid-treated silages had significantly lower pH and VFA contents than the untreated silage.After 126 d and 98 d storage periods in experiments 1 and 2 respectively, each of the six silages was offered to twelve 475 kg steers throughout a 70-d period (experiment I) and a 63-d period (experiment 2). In experiment 1 there were no significant effects of additive on silage DM intake, liveweight gain or carcass gain with the mean carcass gains being 0·49, 0·51 and 0·52±0·024 kg d−1 for the untreated, formic acid-treated and inoculant-treated silages respectively. In experiment 2 the mean silage DM intakes were 6·34, 7·33 and 6·60±0·151 kg d−1 and carcass gains were 0·27, 0·35 and 0·26±0·026 kg d−1 for the untreated, formic acid-treated and inoculant-treated silages respectively, formic acid treatment thus gave the most consistent results.

Notes: Changes in stubble carbohydrate content during the regrowth of ryegrass (Lolium perenne L.) grown under hydroponic conditions at two nitrogen levels were studied as a function of time by high-performance liquid chromatography. Experimental data showed that regrowth at a non-limiting nitrogen level (1·0 mol m−3 NH4NO3) involved two different physiological periods. The first occurred during the first 6 d and was characterized by the mobilization of 60 to 90% of the soluble carbohydrates (i.e. glucose, fructose, sucrose, oligofructans and polyfructans). During the second period (6.28 d of regrowth) carbohydrate contents rose to the values observed prior to cutting (20% of dry matter at the 28th d of regrowth).The effect of low nitrogen conditions (0·2 mol m−3 NH4NO3) was observed only during the second phase. Plants regrown in a nitrogen-starved medium accumulated 2·3-fold more polyfructans than plants regrown in a non-limiting nitrogen medium. Their fructose and glucose contents remained at 2% of dry matter from the end of the first phase of mobilization.The experimental results are interpreted and discussed in terms of the existence of two distinct fructan synthetic pathways.

Notes: Comparative sheep production from Aurora (very early-flowering), Meltra (late-flowering tetraploid) and Aberystwyth S23 (late-flowering) perennial ryegrass (Lolium perenne L.) varieties was assessed as both grass-only (200 kg N ha−1) and grass-white clover (Trifolium repens L.) (75 kg N ha−1) swards under continuous stocking management. Beulah Speckled Face ewes and their Suffolk cross lambs were used from late April to mid-July. From late July to early November only lambs grazed the pastures.Mean (1985–87) total annual lamb production per hectare from Aurora and Meltra was 16% and 13% more than that from S23. The magnitude of the differences between these varieties and S23 declined from the first to the third year. Aurora gave 29% more lamb output per hectare than S23 in 1985 but only 10% more in 1987, while the advantage of Meltra over S23 fell from 19% in 1985 to 6% in 1987. Seasonal lamb production per hectare varied between the grasses, especially during spring when lamb output from Aurora was 43% and 22% more than that from S23 and Meltra respectively, with that from the tetraploid being 17% higher than that from S23.It is concluded that the superior spring output from Aurora offers the farmer the opportunity to reduce his dependence on bought-in feedstuffs, hence improving the efficiency and profitability of lamb production from grassland.

Notes: The effects of rate and pattern of fertilizer S application on herbage production from Perennial ryegrass-dominant swards at six potentially S-deficient sites in south-west Scotland were measured under a silage cutting regime (3 cuts year-1) with high fertilizer N application (300 kg ha−1 year-1). Fertilizer S (as gypsum) was applied at annual rates from 0 to 48 kg ha−1 as single spring applications before the first cut or split before each of the three cuts. The residual effect of S in the year following its application was assessed at one site.Applied S increased total DM production at four of the six sites. These increases were restricted to the second and/or third cuts and were generally in the range 10-30% greater than where no S was applied. Timing of S application was not important in influencing annual DM yield. The residual effect of gypsum in the year following application was small.The supply of available soil S is limiting herbage production in certain areas and soil types of south-west Scotland. Areas of S deficiency are likely to increase in the future and need to be identified more precisely than they are at present.

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

Notes: Book reviewed in this articles: Seed Production of Agrieultural Crops A. Fenwick Kelly

Notes: In two experiments in established swards of perennial ryegrass and white clover, plots were treated with pesticides to control slugs, leather-jackets, weevil larvae and lucerne flea as selectively as possible. Other plots were treated to control ail of these pests.Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather-jackets. Other effects on non-target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3-year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha−1 in the final year. At the other site, where the clover content was low (ultimately 01.1–6%), leather-jacket populations reached 2.1 m ha−1 and slug numbers were also relatively high. Control of these species contributed most to the relative increase in clover content and yield.

Notes: Data are few on concentrations of nitrogen (N) in the cell wall and lignocellulose (neutral- and acid-detergent fibre (NDF and ADF), respectively) of herbage. Herbage N can be partitioned into neutral- and acid-detergent soluble and insoluble N to crudely estimate rapidly degradable (N soluble in neutral detergent), slowly degradable (neutral-detergent fibre N (NDFN) minus acid-detergent fibre N (ADFN), herein termed available fibre N (AFN)), and indigestible N (ADFN) in the rumen. Our objective was to examine the effects of herbage species, maturity stage, and plant part on N in the NDF and ADF of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and smooth bromegrass (Bromus inermis Leyss.). Herbage was harvested at four 2-week intervals during spring of 1984 and 1985. Leaves, stems and total herbage were analysed for total N, and N in NDF and ADF. Concentrations of N in ADF in leaves, stems, and total herbage of lucerne and clover were twice that of grass ADF. This may be due to greater lignin concentrations generally reported in legumes. Concentrations of NDFN in leaves of lucerne, clover, timothy, and bromegrass were 9–8, 26.4, 8.6, and 6.4 g kg−1 of NDF, respectively, averaged over harvests and years, whereas stem concentrations were 4.2, 4.6, 32, and 2.4 g kg−1 of NDF, respectively. Leaf concentrations of ADFN in lucerne, clover, timothy, and bromegrass were 4.6, 5.3, 20, and 1.6 g kg−1 of ADF, respectively, averaged over harvests and years, whereas stem concentrations were 3.4, 33, 14, and 14 g kg-’of ADF, respectively. As a proportion of the total N, NDFN and ADFN increased with plant maturity in leaves, stems, and herbage. In stems, 49% of NDFN was ADFN, whereas in leaves only 21% of the NDFN was ADFN. The larger portion of ADFN in stems probably reflects the larger proportion of lignified xylem and other structural tissues, which have a greater proportion of lignified secondary cell walls, whereas the greater proportion of NDFN in leaves may mirror the greater amount of mesophyll cells with primary cell walls. More than 80% of the total N in leaves, stems, and herbage was in the cell solubles, which may be rapidly ruminally degradable.

Notes: The use of sward height as a criterion for determining the time and extent of stocking-rate changes on continuously grazed swards was investigated over a 2-year period (1985–86) in a sheep production experiment. Swards of three contrasting perennial ryegrass (Lolium perenne L.) varieties were established with and without Aberystwyth S184 small-leaved white clover (Trifolium repens L.) at an upland site (310–363 m) in mid-Wales. From spring (late April) until weaning (mid-July) the pastures were continuously stocked with Beulah Speckled Face ewes and Suffolk cross lambs. During this period sward heights of 4 ± 0.5 cm were obtained and maintained by regular adjustment of animal number on individual paddocks. Grass-only swards received 160 and 200 kg N ha−1 and the grass clover swards were given 80 and 75 kg N ha−1 in 1985 and 1986 respectively.Differences were observed between the treatments in sward height profiles over the season necessitating contrasting adjustments to stocking rates. Mean stocking rate necessary on early flowering Aurora (22 6 ewes ha−1) was respectively 27% and 17% higher than on late-flowering Aberystwyth S23 and Meltra (tetraploid) ryegrasses; mean stocking rate on grass-only swards was 19% higher than on the grass-clover pastures.It is concluded that sward height is a useful criterion on which to make adjustments to stocking rates to compare the potential performance of contrasting swards, under continuous grazing. The infrequent adjustments required to maintain a constant sward height, especially on the late flowering diploid perennial ryegrass variety on which many upland pastures are based, suggest that the criterion of sward height could be successfully employed on farms as an aid to efficient grazing management.

Notes: A hay drying model (HAYDMO) which predicts the moisture content of pasture hay is described. It uses multiple regression equations based on field drying experiments with conditioned and unconditioned hay and predicts hourly changes in moisture content for both day and night and also those due to rain. The model can be used with three different combinations of weather, including hourly wet and dry bulb temperatures, radiation, wind speed and rainfall. Testing HAYDMO revealed a satisfactory agreement between predicted and observed moisture contents

Notes: A field investigation into the effect of slurry seeding on the dry-matter yield and persistence of an Italian ryegrass sward was assessed over a 3-year period (1984–86) under a regime of three cuts per season combined with sheep grazing in early spring and late autumn. Results showed that slurry plus seed treatments produced up to 30% more herbage dry matter and a significantly higher tiller density than where no slurry or seed were used. Slurry application with and without seed also reduced the proportion of weed grasses (mainly Poa spp.) in the sward. It is concluded that slurry seeding is a useful technique for extending the productive life of an Italian ryegrass sward.

Notes: Rates of leaf extension and senescence were measured over three-day intervals on neighbouring sets of caged and uncaged tillers on several occasions during summer 1983, both when grazing animals were present and also when they were absent. The weather was dry and drought conditions developed as the season advanced.Comparison of data from caged and uncaged tillers indicated that some consistent differences occurred. Loss of information through grazing (affecting 30% of uncaged, larger than average, tillers), contributed to the significantly reduced estimates of leaf extension of ungrazed, uncaged tillers compared with caged tillers. Senescence rates were higher in the open plot than under the cages; old leaves were grazed on only 8% of uncaged tillers so that data loss was less important as a cause of bias. In the drought conditions prevailing, it was thought that caging in the presence of grazing animals resulted in reduced moisture stress and contributed to the above results.Comparisons of caged and uncaged tillers when grazing animals were absent were made to examine the environmental effects of caging and the slight difference in tiller marking procedure. No differences were found in leaf extension rates, though a trend towards higher senescence rates for the uncaged populations was evident. It was concluded that the criteria limiting the use of cages (a period of protection less than the average interval between both leaf appearance and repeated defoliation) should be extended to include a time limit set by the need to avoid bias associated with the environmental effects of caging and cessation of grazing. To define this time limit better in particular circumstances, the extent and direction of bias in the estimation of leaf extension and senescence rates as affected by period of caging, tiller handling procedures, sward and climatic conditions requires further investigation.In the case of vegetative tillers, estimates of leaf extension rates can be made considerably more precise by using tiller size variables (pseudostem length, total green leaf length, leaf width) as covariates. A suggestion for the number of tillers to be measured per transect is given. However, no such increase in precision can be made for estimates of senescence rates.

Notes: To investigate links between the anatomy of grass leaves and their resistance to breakdown in the rumen, leaf blades of the tropical grass, green panic (Panicum maximum var, trichoglume), and the temperate grass, Italian ryegrass (Lolium multiflorum), were chopped into 50 mm lengths and fed fresh to cattle. Particle size reduction of the chewed feed was studied immediately after eating and after digestion in nylon bags in the rumen for 6, 12, 24, 48, 96 h and 3 weeks. The lengths of fibre elements, separated into groups of different diameters, were measured on samples digested for 96 h. The process of tissue breakdown was studied using light and electron microscopy.Green panic leaves had twice the cross-sectional area of thick-walled tissues, a higher vascular bundle frequency per unit leaf width, and less, but more densely packed mesophyll, than did the ryegrass leaves. Despite the contribution of these characteristics to greater leaf rigidity, green panic was broken down to a greater degree by chewing than was ryegrass.During digestion, width reduction of the chewed leaf particles was faster in ryegrass than in green panic because of two anatomical features: (i) the straight-walled intercostal cells of the epidermis in ryegrass were easily separated allowing the epidermis to split, whereas the sinuous walls in green panic were resistant to splitting, and (ii) the epidermis of ryegrass was linked to the vascular bundles by thin-walled mesophyll cells and was shed when these were digested, whereas in green panic the linkage was via thick-walled bundle sheath cells causing the epidermis to remain attached for much longer. Ryegrass leaf was reduced to isolated fibres within 24 h digestion; this process took 〉48 h in green panic. These fibres all had a high resistance to length reduction by digestion irrespective of their anatomical or species origin. Even after 3 weeks in the rumen there was little digestive disruption to the longitudinal walls of these fibres.The isolated vascular fibres of ryegrass were smooth-surfaced in contrast to those of green panic which were rough owing to attached undigested bundle sheath cells and jagged, broken sections of epidermis; this could influence ease of separation of particles from the digesta mass and flow from the rumen.Anatomical differences between these grasses were, therefore, important in the rate of width reduction of leaf particles during digestion and for the characteristics of the isolated fibre, but not for length reduction of particles during digestion

Notes: Mefluidide was applied at 150ga.i.ha−1 on one of three dates (7, 28 March or 18 April, 1984) to irrigated field plots of nine grasses. Spraying suppressed flowering in the primary growth of most species, especially when carried out in mid- April. However, spraying at this time proved too damaging to amounts of herbage harvested. Spraying in March reduced mean yields by about one-third at the first harvest and increased mean yields at the second harvest. In addition, spraying at this time increased herbage quality, as indicated by higher N and lower fibre contents, at least at the first harvest. In general, the grasses most responsive to mefluidide were tall-growing and/or early-flowering species, e.g. Arrhenatherum elatius, Festuca rubra, Dactylis glomerata and Holcus lanatus; by comparison, Lolium perenne was relatively less affected by spraying. The findings indicate the potential of mefluidide for overcoming the normal decline in herbage quality associated with flowering, and for transferring growth from spring to midsummer, albeit at some cost to total annual production.

Notes: The hydrogen cyanide potential (HCNp) of 17 cultivars of white clover were compared. With inadequate phosphorus supply, HCNp ranged from 24 mg kg DM−1 for cv Lucky to approximately 640 mg kg DM−1 for cv Huia and from 6 to 322 mg kg DM−1 for the same cultivars, with adequate phosphorus. The four North American cultivars examined had notably lower HCNp than all European or Australasian cultivars except cv Clarence.

Notes: Water-soluble carbohydrate (WSC) contents of the early heading perennial ryegrass cultivar Aurora and five late heading cultivars were assessed in samples from spaced plants cut five times in 1982. Aurora had the highest overall WSC content. Majestic and Aberystwyth S23 had the lowest while Perma, Melle and Ba 9795 were intermediate. Samples from F1 and F2 spaced plants derived from crosses between Aurora and the five late heading cultivars were also analysed for WSC contents and heading dates were recorded. As expected, heading date behaved as a polygenic character controlled mainly by additive gene effects. However, WSC contents behaved in a more complex way with evidence of non-additive gene effects comprising dominance, overdominance (heterosis) and epistasis. It was concluded that by crossing contrasting cultivars, significant improvements in WSC content could be achieved, which may be more stable than those obtained by within-cultivar selection.

Notes: An experiment was conducted to measure the survival and growth of juvenile Dungeness crabs (Cancer magister) when fed purified crustacean diets in intensive laboratory culture. Wild-caught juvenile crabs were held individually and fed either a casein-based diet previously used for lobster experimentation (diet BML-81 S), a crab protein-based diet (HFX-CRD-84), or a closed-formula commercial fish (trout) diet. Diets BML-81 S and HFX-CRD-84 have been proposed as possible general crustacean reference diets. The crab protein-based diet appeared to be more attractive to the crabs, but after a 90 day experimental period there were no significant differences (P 〈 0.01) in growth or survival between crabs fed the proposed reference diets; however, survival on the trout diet was significantly reduced. Results are discussed in relation to the rearing conditions and the composition and physical characteristics of the diets.

Notes: Adult red swamp crayfish (Procambarus clarkii) were held in fecal collection chambers and fed common feedstuffs in two different types of diets, as the sole feedstuff and as a 30% substitution in a reference diet. Feedstuffs tested were soybean meal, peanut meal, wheat shorts, cooked corn, menhaden fish meal, and shrimp-head meal. Feed consumption, apparent digestible dry matter, and energy coefficients were determined for feedstuffs when fed in both diets. Addition of menhaden fish meal, shrimp-head meal, and peanut meal in the reference diet resulted in decreased consumption, and menhaden fish meal was poorly digested when incorporated at 30% in the reference diet. Apparent dry matter and energy digestion coefficients Indicated that plant feedstuffs have greater potential as ingredients in crayfish diets than feedstuffs of animal origin. Differences in consumption and digestibility between the two types of diet were observed. Therefore, it appears that the associative effects of additions of feedstuffs in diets should be considered when formulating crayfish feeds.

Notes: Growth of juvenile Florida red tilapin (1.57 g average weight) spawned and sex-reversed (monosex male) at salinities of 4 ppt and 18 ppt was compared at rearing salinities of 18 ppt and 36 ppt in 200 L aquaria under controlled photoperiod (12 L:12 D) and temperature (28 C). Growth was significantly higher for progeny spawned at 18 ppt than those spawned at 4 ppt under both rearing salinities with no difference observed between 18 ppt and 36 ppt.In another experiment, growth of juvenile progeny (0.98 g average weight) spawned and sex-reversed at salinities of 2 ppt and 18 ppt was compared in 24 m3 outdoor pools at 36 ppt. When water temperatures exceeded 27 C, growth and survival were not significantly different between these groups. However, when temperatures fell below 25 C, growth and survival were significantly higher among progeny spawned at 18 ppt.The results showed that progeny spawned and reared through early ontqenetic development in brackishwater are better adapted for growth in brackish and seawater and suggested that these fish may have higher resistance to cold-stress in seawater than progeny spawned in freshwater.

Notes: The nutritional quality of the harpacticoid copepod Euterpina acutifrons, freshly-hatched Artemita nauplii, juvenile and adult Artemia, and the rotifer Brachionus plictatilis, in fed and starved conditions, was evaluated through the use of ratios of dry weight to wet weight (DW/WW), ash-free dry weight to dry weight (AFDW/DW), calories per mg ash-free dry weight (cal/mg AFDW), and carbon to nitrogen by weight (C/N). E. acutifrons had in nearly all cases the highest values of DW/WW, AFDW/DW, and cal/mg AFDW. Calculated losses in caloric content per unit of wet weight (cal/mg WW) during one day's starvation were similar among species, ranging from 3 to 52 percent. C/N ratios were less variable, but also reflected starvation-related changes indicating depletion of C relative to N, which is consistent With depletion of lipids and carbohydrates relative to protein.Because little or no change in caloric density of organic material (cal/mg AFDW) was observed in any species under either condition, decreases in caloric content of wet weight or of individuals were due to decreases in DW/WW and AFDW/DW. Caloric content and carbon content were related by the factor 11.3 cal/mg C. Starvation-related losses in the nutritional value of forage organisms can be important in larval rearing systems.

Notes: To establish the practical use of microbound diets (MBD) for larval fish in mass seedling production, rearing experiments of larval red sea bream, Pagrus major, and Japanese flounder, Paralichthys olivaeeus, were conducted. A mixture of various protein sources was used, and dietary amino acid patterns were approximated to those of larval whole body protein. Two thousand red sea bream larvae and 1,000 Japanese flounder larvae, all 10 days old, were placed in 100 liter tanks with running sea water under ambient water temperature, which ranged from 18 to 20C. The particle size of MBD was 125 μm at the beginning of the experiment and adjusted as fish size increased thereafter. Employing MBD together with a small amount of live food could sustain the growth and survival of larval red sea bream and Japanese flounder. Thus, data from the present study indicates that substitution of artificial feeds for live foods is possible for larval fish production, although improvements in MBD diets may be necessary before they are adequate for large scale seedling production.

Notes: The polyunsaturated fatty acids of the n-3 family associated with fish and fish oils have been shown to have beneficial effects on prevention of heart disease in humans. However, in considering the potential health benefits of fish oil in human health, it is important to realize that the fatty acid composition and total lipid content of fish vary greatly. These variations may be due to species differences or variations within a species due to temperature, diet, developmental stage, sex or seasonal differences.The purpose of the study described here was to determine the effects of season, size class, and sex on the Occurrence of individual fatty acids in striped bass (Morone saxrrtilis). Fish were collected in June, July, August, September, and October. Filets with skin were analyzed for total lipid content. Methyl esters of fatty acids were separated and identified using capillary gas chromatography. Total mean lipid varied from as low as 12% to as high as 30%. There were no significant changes in total crude lipid content due to month collected or sex. However, total lipid content of filets increased significantly (P ≤ 0.05) as size increased.The fatty acids 18:1n–9 and 16:0 made up the majority (62%) of the fatty acids present in any season, size class, or sex. The monounsaturated fatty acids dominated in all fish. There were no significant differences in individual fatty acids due to sex. However, fish size had a significant influence on fatty acid composition. Overall, saturated fatty acids decreased as size increased, while polyunsaturated fatty acids increased or remained constant. There were no significant changes in mean percent saturated or monounsaturated fatty acids with respect to month when controlling for size. However, total percent polyunsaturated fatty acids decreased significantly in October compared to August and September. This overall decrease was due mainly to a decrease in 22:6n–3. Conversely there was a significant increase in 16:11n–9 in October. All other fatty acids remained constant. When data from this study were compared to fatty acid data from the literature, striped bass was not as good a source of 20:5n–3 and 22:61n–3 as sardines, anchovies or mackerel.

Notes: Penueus vannumei larvae (P2 through M3) and early postlarvae (〈24 h old postlarva) were fed diets consisting of algae-only, nematodes (Panugrellus redivivus) plus algae or Artemia plus algae. Growth (dry biomass gain) of second and third stage protozoea larvae fed the nematodealgae diet was significantly better than that of larvae fed the Artemia-algae diet. From the first mysis through the postlarval substage (〈24 h old), growth of shrimp fed the nematodealgae diet equalled that of larvae fed the Artemia-algae diet. All larval substages fed nematodes plus algae accumulated significantly greater biomass than those fed a diet of only algae. Survival and percent metamorphosis of larvae fed nematodes plus algae did not differ significantly from that of larvae fed either Artemia plus algae or algae alone. A nematodealgae feeding regime, which potentially yields growth, survival and metamorphosis equal to that obtained on the standard Artemia plus algae regime, is proposed for P. vannamei.