Comparison of the relative performance of perennial ryegrass varieties under upland and lowland conditions     

D. A. DAVIES  E. L. JONES  T. E. H. MORGAN 《Grass and Forage Science》1985,40(3):323-330

Productivity, seasonal growth and persistence of 10 perennial ryegrass ( Lolium perenne L.) varieties were assessed al an upland (305 m) and lowland (30 m) site in mid-Wales. Averaged over 3 harvest years (1979–81), mean dry matter (DM) production at 8.8 t ha⁻¹ was 22% lower in the upland environment, with spring (April and May) growth showing greatest contrast varying from only 6% of that in the lowland in 1979, after a severe winter, to 113% in 1981.
Relative ranking of varieties differed considerably between the two environments and no correlation was found between DM production at the two sites ( r = 0.5945). Early heading varieties performed better in the spring than late types at the upland site. A comparison of the results with those published from official variety testing trials gave a positive relationship under lowland conditions ( r = 0.7162*) but no correlation with those from the upland centre ( r = 0.1969).
The findings of the study show that relative productivity of varieties, but not persistency, differs between upland and lowland environments.  相似文献   

Comparative sheep production and herbage characteristics on four perennial ryegrass varieties in the uplands     

D. A. DAVIES 《Grass and Forage Science》1987,42(3):233-239

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

Dilatation of the Ampullae and an Increased Incidence of Loose Sperm Heads after Bilateral Vesiculectomy in a Bull     

JO Nöthling  DH Volkmann 《Reproduction in domestic animals》1997,32(6):321-324

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A SIMPLE AND INEXPENSIVE APPARATUS FOR AUTOMATICALLY CONTROLLING SOLUTION FLOW RATES THROUGH SOIL COLUMNS     

I. J. GRAHAM-BRYCE  R. I. DAVIES  A. A. H. AL-RAWI 《European Journal of Soil Science》1967,18(1):39-41

Accurate control of rate of flow of solution through soil columns is important in laboratory studies of leaching, but is difficult to achieve because of fluctuations in permeability. A simple and inexpensive method of automatically maintaining a constant flow-rate through several columns simultaneously is described. The apparatus comprises (i) a rotating delivery system which distributes the leaching solution equally to eight compartments, (ii) a system for automatically regulating the flow through each column to keep pace with the solution delivered, and (iii) an automatic fraction-collector to collect the effluent from the columns. Using this apparatus the standard deviation of the volumes delivered to the eight individual columns was less than 2 per cent of the mean, provided the flow rate was faster than 10 ml/h.  相似文献   

Fate of fertilizer nitrogen applied to grassland. I. Field leaching results     

D. BARRACLOUGH  M. J. HYDEN  G. P. DAVIES 《European Journal of Soil Science》1983,34(3):483-497

Results are presented from a 3 year investigation into nitrate leaching from isolated 0.4 ha grassland plots fertilized with 250, 500 and 900 kg N ha^?1 a^?1. Cumulative nitrate leaching over the 3 years was equivalent to 1.5%, 5.4% and 16.7% of the fertilizer applied at 250, 500 and 900 kg N ha^?1 rates respectively. Over a whole drainage season, mean nitrate leachate concentrations at 250 kg N ha^?1 did not exceed 4 mgl^?1, although maximum values of 13.3 mgl^?1 were observed. In contrast, at 900 kg N ha^?1, the mean nitrate leachate concentration in two of the years exceeded 90 mgl^?1. Mineral nitrogen balances constructed for the 1979 growing season indicated that leaching at 250 kg N ha^?1 was low because net mineralization of soil organic nitrogen was small, and crop nitrogen uptake almost balanced fertilizer application. Although the pattern of nitrate leaching suggested that by-passing occurred in the movement of water down the soil profile, it was not possible to confirm this using simulation models of leaching. Possible reasons for this, including the occurrence of rapid water flow down gravitationally drained macropores, are discussed.  相似文献   

Trace elements in surface soils from the mineralized area of Madison County, Missouri, U.S.A.     

B. E. DAVIES  B. G. WIXSON 《European Journal of Soil Science》1985,36(4):551-570

Duplicate, bulked surface soil samples, from sites 10m apart, were collected at 97 locations 1000 m apart on a regular grid measuring 8x11 km. Data were obtained for Ag, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Ni, Pb, V and Zn. One field sample was a good predictor of its nearby duplicate for Co, Cu, Ni and Pb, satisfactory for Ba, Be, Cr, Mn and Zn, but poorer for Cr, Li and V. Maps of the variation in precision of the field samples did not reveal any association between abandoned mine sites and high variability. The median coefficient of variation for trace elements in the field duplicates was between 8 and 19.5%. The duplicated field data were averaged to yield a mean soil metal concentration at each sample location. Concentrations of Ba, Be, Cr, Li, Sr and V were comparable with other published values for similar soils in Missouri. Concentrations of Co, Cu, Mn, Ni, Pb and Zn were higher which was explained by pollution from mining activities. A graphical technique was used to calculate background levels for metals in the second group. Samples of forest litter were collected at 12 locations: Ag, Ba, Cd, Mn, Sr and Zn concentrations were higher in the litter whereas Li and V concentrations were higher in the subjacent mineral soil. Computer isoline maps of the distribution of elements revealed an association between areas of high soil Cu, Co, Ni, Pb and Zn and abandoned mines or mineralized rocks.  相似文献   

The treatment of foul in the foot in cattle,using sulphapyridine soluble     

DAVIES DG  WYNNE M 《The Veterinary record》1947,59(50):687

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The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria     

DJ HARRIS  CD HIBBURT†  GA ANDERSON‡  PJ YOUNIS†  DH FITSPATRICK§  AC DUNN¶  IW PARSONS  NR McBEATH 《Australian veterinary journal》1988,65(6):171-176

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.  相似文献   

Chronic cervical compressive myelopathy in horses: patterns of astrocytosis in the spinal cord     

JV YOVICH  DH GOULD†  RA LeCOUTEUR† 《Australian veterinary journal》1991,68(10):334-334

The distribution and morphology of fibrous astrocytes in the cervical spinal cord of normal horses and horses with chronic compressive myelopathy were demonstrated using immunohistochemical staining for glial fibrillary acidic protein. In the spinal cord from normal horses, astrocytes with stellate cell bodies and short processes were irregularly distributed in grey matter. In the white matter, their cell bodies were small and angular in areas adjacent to grey matter and larger and more stellate-shaped in the subpial area. Astrocyte processes were fine, and evenly distributed in a predominantly radial pattern in transverse sections of cord. Gliosis was marked in the spinal cords of horses with cervical compressive myelopathy. In the grey matter at the level of compression astrocytes were often enlarged and rounded, with short, blunt processes, but the gliosis was generally mild. In the white matter, gliosis was obvious in areas of nerve fibre swelling and degeneration at the level of compression and in areas of ascending and descending Wallerian degeneration. The fine radial pattern of astrocyte fibres was replaced by a dense, irregular arrangement. Gliosis persisted in the cords of chronically affected horses after active nerve fibre degeneration had subsided. The areas of gliosis coincided with the areas of Marchi staining for degenerating myelin and with areas of myelin loss in osmium tetroxide post-fixed tissue. Histological observations were consistent with astrocytes replacing areas of extracellular space that remained after nerve fibre degeneration. it is concluded that astrocytic gliosis is a prominent and persistent alteration of the spinal cord of horses with chronic cervical compressive myelopathy.  相似文献   

A congenital haemolytic anaemia and jaundice of Murray Grey calves     

TJ NICHOLLS  DH PRITCHARD  DH PRITCHARD  JJ McKEE 《Australian veterinary journal》1992,69(2):39-40

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