摘要:

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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02108.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractFour legumes—white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Europe—were established as pure‐sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of ‘intermediate’ heading date. Two ‘silage’ crops and an ‘aftermath grazing’ crop were harvested in each of three successive years.In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha‐1. White clover and lucerne swards produced considerably less at 7·12 to 11·01 t ha‐1. In the second harvest year, lucerne swards were the highest producing at 15·54 to 17·14 t ha‐1, while DM production from red clover and white clover swards ranged from 6·75 to 11·87 t ha‐1. Lucerne swards maintained their production superiority in the third year at 16·48 to 17·87 t ha‐1, while production from white clover swards ranged from 6·41 to 10·23 t ha‐1. However, red clover swards declined to 3·30 to 5·81 t ha‐1; this above‐average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02109.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractPot experiments and a hand‐weeded field trial were carried out to investigate the direct effect of ethofumesate on the growth and development ofLolium perennecv. S24.In the field trial, ethofumesate was applied in autumn as Nortron 20% ec formulation in a volume of 2001 ha‐1at rates of 0, 1 or 2 kg a.i. ha‐1. Treatments had no direct effect on yield in the following summer. In both the field trial and pot experiments there was initial growth suppression in the form of a reduction in shoot dry weight, lamina dry weight, tiller number per plant and plant height. However, ethofumesate increased the chlorophyll and nitrogen contents ofL. perennelaminae, but only when available soil nitrogen was not limited.It is concluded that ethofumesate can increase the yield ofL. perenneby suppressing weed competition, but there is no evidence of the herbicide directly increasing the growth or yield of cv

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02110.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02111.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

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

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02112.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn a trial lasting 3 years at Jealott's Hill and 2 years at Ravenscroft Hall, a total of 73 January‐ March‐calving Friesian x Holstein cows and heifers were given a diet consisting almost exclusively of ensiled and grazed ryegrass for an entire lactation to establish the level of milk production which grass alone can support. From calving to turnout in April/May (average duration 87 days), the animals were given high digestibility (DOMD = 678g kg‐1DM) ryegrass silage ad libitum. After turnout, they grazed ryegrass swards until housing in autumn. Thereafter, the cattle were given ryegrass silage of lower digestibility (DOMD = 600–620 g kg‐1DM) for the remainder of the lactation and during the dry period.Mean silage dry matter intakes from calving to turnout were 13–2 kg day‐1at Jealott's Hill and 11·5 kg day‐1at Ravenscroft Hall. Average milk yields were 21‐1 kg day‐1for cows and 16‐1 kg day‐1for heifers with 39‐2g fat kg‐1, 29‐6g protein kg‐1and 47–9 g lactose kg‐1. Over the complete lactation, average milk yields were 4680 kg and 4006 kg for the cows and heifers, respectively, with 39‐4 g fat kg‐1, 31·4 g protein kg‐1and 46·9 g lactose kg‐1. Animal health and fertility were satisfactory. The results demonstrated the value of high quality grazed and ensiled ryegrass and provide

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02113.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractHigh rainfall and the corresponding low herbage DM content has been shown to adversely affect cattle intakes and production. This could arise from physical restrictions on intake or digestion rate, or other behavioural limitations such as reduced palatability. A knowledge of the reason for the intake reduction would assist in determining the optimum supplement to feed. Eight steers were offered four diets in a changeover design. The diets were: A, cut herbage; B, cut herbage with added surface water; C, as B but with a low dry matter (DM) forage supplement (silage); and D, as B but with a high DM forage supplement (hay). The addition of surface water to herbage reduced DM intake and feeding time but had no effect on biting rate or rate of intake. Neither hay nor silage was eaten in sufficient quantities to restore DM intake, even though the silage was of similar nutrient composition to the herbage.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02114.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractSwards of perennial ryegrass/white clover were cut to 3 cm in March and allowed to regrow for approximately thirteen weeks. Half the swards received nitrogenous fertilizer at the time of cutting (+N treatment) while the other half received none (—N treatment).About four weeks after the application of treatments, the number of clover shoots in the — N treatment was significantly higher than that in the +N; at this stage total leaf area index on both treatments was low, but significantly greater in the + N. After 30 days, more light was reaching ground level in the — N treatments, and about 40 days after cutting there was between 17 and 50% more clover in the — N treatment than the +N.It is suggested that the inhibition of stolon branching with a consequent restriction in the rate of increase of clover leaf area is a major factor in the adverse effect of N fertilizer on

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02115.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe productivity of a mixed sward comprising perennial ryegrass cv. Fantoom and white clover cv. Aran was measured under eight defoliation management systems and two fertilizer N rates (0 and 75 kg ha‐1) applied in spring. The defoliations involved a basic six‐harvest simulated grazing system together with the interposition of silage cuts once or twice at varying times during the growing season; evaluation was made over three harvest years, 1983‐85.Mean annual production of total herbage DM over the three years was 8.351 tha‐1without N and 9.49 tha‐1with 75 kg N ha‐1, a mean response of 15.2 kg DM per kg applied N. The responses for individual treatments occurred mainly at the first cuts, whether for simulated grazing (a mean of 12 9 kg DM) or for silage (a mean of 259 kg DM); however, this influence of spring N was not sustained at other cuts over the season. Mean annual white clover DM production was 4.19 t ha‐1with no N and 3.32 t ha‐1with 75 kg ha‐1N, but the reduction due to N was not significant in any year. The mean amount of clover stolon DM present post harvest over all management systems was 1.33 t ha‐1with no N and 1.03 t ha‐1with 75 kg ha‐1N.Mean annual DM production of total herbage from the six‐harvest system was 8.11 t ha‐1Compared with 8 88 t ha‐1(a 9% increase) from the systems with one silage cut and 9.241 ha‐1(a 14% increase) from the systems with two silage cuts. Corresponding white clover DM production was 4.02, 3 87 and 3 53 t ha‐1, respectively, and mean stolon DM amounts post harvest, 1 12,1.15 and 1‐23 t ha‐1, respectively.It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. Spring N application did not greatly reduce white clover production in this experiment where white clover was at higher levels than are likely in farming practice and the swards were not grazed. More knowledge of spring N rates, and indeed of N application rates generally, would be advantageous in future

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02116.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractExperiments were carried out over four years to develop a system of buffer grazing. Groups of 16 cattle were set stocked with or without buffer areas formed by withholding a proportion of the grazing area by electric fence. It was found that buffers should be grazed if sward height, measured by rising plate meter, was reduced below 5 cm, or otherwise cut for silage. Increasing the area of the buffer reduced cattle gains but increased silage yield and sward quality, and the best compromise over 4 years was a buffer area of 25‐30% of the initial grazing area. Buffer treatments gave higher UME and financial output than controls, due to the value of silage from the buffers and to the higher nitrogen inputs which were successfully managed under buffer grazing. The higher outputs over 4 years were also associated with lower viability and therefore lower levels of risk, resulting from a number of compensating processes at sward and animal level. There was no indication that grazed UME was higher on buffer treatments at a given level of nitrogen, suggesting that any increased grazing efficiency must be offset by other disadvantages when comparing intensive with lax defoliation regimes. The results suggest that there is considerable stability in grazing systems which may frustrate attempts to improve their biological efficiency, although there is some scope for manipulating the seasonal pattern of land use and animal performanc

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1987.tb02117.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY