bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ neutron diffraction studies on the elevated-temperature deformation behavior of a TiAl–W alloy
Authors: Choo Hahn , Seo Dongyi , Beddoes Jonathan , Bourke Mark A. M. , Brown Donald W.
Published: November 2004

The evolution of elastic lattice strain in a Ti–48Al–2W (at.%) alloy, subjected to (1) quasistatic tensile loading and (2) constant-load tensile creep, was investigated at 1033K using in situ neutron diffraction. During the quasistatic test to a maximum stress of 435MPa, a- and c-axes lattice strains increased linearly with a small degree of anisotropy (E¯a∕E¯c≅0.9) up to 200MPa, followed by a significant redistribution of load above 260MPa due to the plastic anisotropy. Time-resolved in situ measurements were also performed during the creep at 276 and 327MPa. The results show that lattice strain evolution during the primary creep is qualitatively similar to the quasistatic case under the current test conditions.
Study of ultrahigh-order modes in a symmetrical metal-cladding optical waveguide
Authors: Lu Haifeng , Cao Zhuangqi , Li Honggen , Shen Qishen
Published: November 2004

We report theory and experiment on ultrahigh-order modes in a symmetrical metal-cladding thick optical waveguide. The waveguide consists of a LiNbO3 slab or a glass slab with a thickness greater than 0.1mm, two gold films deposited on the upper and bottom sides of the slab serving as the cladding of the waveguide. By using the free-space coupling technique, ultrahigh-order modes (m>2000) are excited, and its high sensitivity to both refractive index and thickness of the guide, as well as the polarization independence are demonstrated.
White organic light-emitting diodes based on 2,7-bis(2,2-diphenylvinyl)-9,9′-spirobifluorene: Improvement in operational lifetime
Authors: Chuen C. H. , Tao Y. T. , Wu F. I. , Shu C. F.
Published: November 2004

Very bright white organic light-emitting diodes were fabricated using 2,7-bis(2,2-diphenylvinyl)-9,9′-spirobifluorene (DPVSBF) doped with [4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran)] (DCJTB) as the emission layer. With a device configuration of ITO∕NPB(40nm)∕DPVSBF:0.2%DCJTB(11nm)∕Alq(30nm)∕LiF(1nm)∕Al(150nm), a brightness of 1575cd∕m2 with an external quantum efficiency of 3.31% and luminous efficiency of 8.00cd∕A, a power efficiency of 5.35lm∕W was achieved at a driving current of 20mA∕cm2 (4.7V). The brightness reached 66000cd∕m2 at 15V. The Commission Internationale de l’Eclairage coordinates stayed nearly constant, changed from (0.35, 0.36) to (0.32, 0.34) when the voltage increased from 6to12V. The relative operational lifetime of the device increased by a factor of ∼20 compared with a similar device based on 4,4′-bis-(2,2-diphenylvinyl)-1,1′-biphenyl as the source of the blue emission. The much extended half-lifetime was attributed to the higher morphological stability of the DPVSBF.
The effect of lateral movement of water in soil on infiltration measurements
Authors: Marshall TJ , Stirk GB
Published: November 2004

The effect of lateral movement on minimum infiltration capacity was examined using small flooded plots of various sizes without buffer zones and using small sprayed and flooded plots surrounded by wetted buffer zones. When no buffer zones were used, the minimum infiltration capacity of a given soil decreased with increasing size of plot and there was a corresponding increase in the fraction of applied water remaining beneath the plot at the conclusion of the trial. An expression for the relation between plot size and lateral movement is discussed. Although buffer zones around flooded plots effected some reduction in lateral movement, the measurements were subject to considerable error and the method was considered unduly cumbersome for routine work. In a spray infiltrometer procedure, a sprayed buffer zone surrounding a small test plot was found to be effective on the soils examined. When all data from flooded plots with and without buffer zones were examined, it was found that the minimum infiltration capacity of a soil varied inversely with the fraction of applied water remaining beneath the plot a t the conclusion of a trial. When the minimum infiltration capacity was multiplied by the corresponding value of this fraction, the effect of lateral movement was reduced considerably. It is shown that results from small plots then approximate more closely to those to be expected from large ones and there is also a reduction in variability due to causes other than variation in size of plot. Limitations in the use of this correction factor are discussed fully and the general limitations of infiltration data derived from small plots are briefly considered.
The effect of calcium and soil pH on nodulation of T. subterraneum L. clover on a yellow podsol
Authors: Spencer D
Published: November 2004

The mechanism of the action of lime in stimulating nodulation of subterranean clover on some soils of the Southern Tablelands of New South Wales was studied in pot experiments. Increased soil pH or increased calcium supply alone did not markedly improve nodulation. With a combination of both these factors, excellent nodulation resulted.
Nodulation was shown to be increased by increasing the amount of the inoculum of Rhizobium added with the seed. It was also increased if the moisture content of the soil was maintained continually at field capacity.
Physical analysis of the fleece of sheep for biological purposes. III. A means of measurement of fibre-length distribution of fleece wool
Authors: Wilson LT , Roberts NF
Published: November 2004

It is suggested that in a staple of Merino wool only the fibres extending from near the base to near the tip should be considered in a number of important biological problems. Equipment has been built by which the straightened length of these fibres can be measured individually, with a considerable saving in time as compared with the usual manual method. Length analyses of a number of samples by mechanical and manual methods are compared. It is shown that these length analyses may be used for analysis of crimp depth, provided a definite crimp form is assumed.
Rotation in relation to take-all of wheat
Authors: Angell HR , Mills M
Published: November 2004

Using an infertile, sandy, alluvial soil in drums, the effect of five rotations on take-all of wheat (Ophiobolus graminis) was tested. The soil was limed initially. The root-infection rating, total grain weight, and total weight of the wheat plants in each year were recorded. The condition of the roots at harvest time in the final year was significantly worse in the ranunculus and oats-fallow rotations, and possibly worse in the two years' fallow, than in the continuous wheat and two years' grass rotations. In contrast with the condition of the roots, the mean grain yield and mean total weight of the wheat plants in the ranunculus, oats-fallow, and two years' fallow were significantly higher than those obtained in the other two rotations. From the results of this experiment it is evident that the mechanism of control is not, as is commonly suggested, the elimination of the root-rotting organism.
The control of molybdenum deficiency in subterranean clover by pre-soaking the seed in sodium molybdate solution
Authors: Donald CM , Spencer D
Published: November 2004

Pre-soaking seed in a sodium molybdate solution was compared with the direct application of sodium molybdate to the soil as a means of preventing deficiency of molybdenum. Subterranean clover, which was used as the test plant, was grown in a molybdenum deficient soil in pot culture for this study.
Pre-soaking in 0.1 per cent. or 1 per cent. sodium molybdate was fully effective in promoting normal growth. The soil and seed treatments were equally effective in promoting yield response at all levels of application examined. At levels of application in excess of the requirements for maximum yield, pre-soaking gave a higher molybdenum content of the tops than did equivalent soil applications. At all levels of application, pre-soaking gave a higher nitrogen content than that resulting from the soil application of molybdenum.
Rate of increase of nematode infestation of tomatoes after soil fumigation
Authors: Giles JE , Brock RD
Published: November 2004

The effect of soil fumigation in the control of root-knot nematode of tomatoes was shown to be due to the reduction in nematode infestation below the level at which it influences yield. The severity of root-gall formation, health, and yield of the plant were used as indices of nematode population. The severity of root-gall formation was found to be a sensitive index of population changes. Within the limits of the experiment the rate of nematode population increase was constant and independent of initial nematode infestation. The time interval necessary between treatments was shown to be a function of the rate of population increase and level of infestation after fumigation.
Maintenance rations for Merino sheep. 1. A comparative study of daily and weekly feeding on rations containing high proportions of wheat and several proportions of roughage to concentrate
Authors: Franklin MC , Sutton PB
Published: November 2004

Groups of full-mouthed Merino wethers were given 4.25 lb. starch equivalent (4,550 calories of net energy) per sheep per week, to maintain a low to moderate store condition of 75 lb. body weight, on each of four rations, namely 50:50, 30:60, 20:80, and 10:90 mixtures of wheaten chaff and wheat. Finely-ground limestone was added to these rations to correct calcium phosphorus imbalance. The groups were paired, one of each pair being given the food once a week and the other being given it in daily portions. The weekly-fed groups were brought on to this regime during a preparatory period of 77 days during which they were fed at intervals which were gradually increased from 3 to 7 days. The surviving sheep in the daily-fed groups maintained their mean body weight and general condition as well as did those in the weekly-fed groups but at the end of the experiment the range in body weight in the daily-fed groups was greater: 41.9 per cent. of the daily-fed animals gained in weight during the period of 344 days, whereas only 14.2 per cent. of the weekly-fed animals did so. This difference was due largely to differences in rate of food consumption. The rate of consumption of the food by the daily-fed groups increased during the progress of the experiment. The sheep receiving the larger amounts of roughage took longer to consume the daily ration. The sheep in the weekly-fed groups ate the week's ration in 4 – 4½ days and occasionally took half a day longer. The death rate in the daily-fed groups was 30.2 per cent, compared with 11.8 per cent. in the meekly-fed group. The deaths occurred mainly (72 per cent.) in the sheep which had lost 40 per cent. or more of their initial body weight. Mean wool production from the daily-fed sheep ranged from 6.73 lb. to 6.94 lb. per sheep, and from the weekly-fed groups from 7.19 lb. to 7.57 lb. Regain of body weight after the termination of the experiment on the low diet was studied. Groups which were retained in pens and fed ad lib. gained steadily in weight and maintained a considerable lead over those which had been turned out to graze. In a group of sheep at pasture there was a close positive correlation between the loss suffered in body weight on the experimental low diet and the subsequent improvement at pasture. The rate and magnitude of subsequent regain of weight were not influenced by the proportion of roughage in the experimental diet or by the origin of the sheep from the daily-fed and weekly-fed groups.
An inverse relationship between atmospheric temperatures and body-weight changes was observed.
The experiments showed that daily feeding of the sheep at levels sufficient for survival was less satisfactory than weekly feeding at the same level.
The practical importance of the results is discussed briefly.
Cytological studies of subterranean clover (Trifolium subterraneum L.)
Authors: Yates JJ , Brittan NH
Published: November 2004

Somatic chromosome number and morphology in certain strains of subterranean clover and in species of several other fairly closely related genera have been observed. Dwalganup, Yarloop, Mt. Barker, Wenigup, Burnerang, and Red Leaf strains have each 16 fairly small chromosomes, the chromosome complexes being similar to one another and to that obtained by Wexelsen (1928) for the species. Palestine and Israel strains have each 12 large chromosomes, bearing no apparent relationship to those of the other strains but being the same in number and of a similar order of size to those found in Vicia sativa. Chromosome number and morphology may explain the failure to obtain intervarietal crosses involving Palestine, but not the low percentage of successful crosses between other strains. It is suggested that perhaps Palestine and Israel may be more correctly classed as strains of a separate species and that, with regard to their origin, Wexelsen's idea of mutational changes in isolated species offers probably the best explanation.
Fertilizer studies on Basaltic red loam soil form the Lismore District, NSW.
Authors: Anderson AJ , Arnot RH
Published: November 2004

A pot-culture study was made -to examine the effects of nutrient elements on the growth of white clover (Trifolium repens L.) and Paspulum dilatutum Poir. on a basaltic red loam soil known to contain a high percentage of phosphorus and free iron vide. The response of paspalum to phosphorus was limited by deficiency of nitrogen. The results indicate that the native phosphorus in the soil is of very low availability, but that the added phosphate is not rapidly converted in the soil to unavailable forms. They suggest also that the response to superphosphate on this soil is restricted by other deficiencies rather than by phosphate fixation. The paspalum responded most to nitrogen on the soil where the lowest yields occurred without added nitrogen. However, the percentage nitrogen in the stunted untreated plants on this soil was higher than in less responsive plants on other soils. The results indicate that the percentage total nitrogen in paspalum is not a satisfactory index of the likely response of the plants to nitrogen. High levels of manganese were found in the paspalum plants which were examined. In an experiment with white clover, molybdenum, deficiency was induced by a light dressing of manganese sulphate. Responses of clover to phosphorus, molybdenum, and sulphur were obtained, and some evidence of calcium and magnesium deficiency is presented. The importance of elements concerned in protein formation in plants in relation to the general problem of pasture improvement on these soils is discussed.
A method of fractionating raw fleece samples and some errors encountered in its use in experimental studies of fleece growth.
Authors: Daly RA , Carter HB
Published: November 2004

A routine quantitative method of separating raw fleece samples into five fractions is described. Moisture content at a known temperature and relative humidity is determined as the loss of weight on drying a t 105°C, wax is Soxhlet-extracted with carbon tetrachloride, suint is extracted by subsequent washings with cold distilled water, dirt is removed by washing and handpicking, and clean wool fibre remains after these fractions have been removed. Some errors detected in the extensive use of this method to provide simple criteria in a variety of field and laboratory studies of fleece growth have been examined. Recovery of original sample weight after fractionation was satisfactory and there was good agreement between the results for duplicate samples. There was a tendency for incomplete separation of suint and for ethyl-alcohol-soluble material, of the order of 1 per cent. by weight, to remain on the clean wool fibre.
Variation between apple fruits and its relation to keeping quality. III. Between-season variation in relation to seasonal climate.
Authors: Martin D
Published: November 2004

Studies were made of seasonal effects on ripening changes and disorder incidence in different varieties of apples in Tasmania for the 10-year period, 1933-1943. Most of the changes associated with ripening, namely, ground colour change, acid loss, starch conversion, soluble solids accumulation, softening, and respiration rise did not necessarily keep pace with each other and responded differently to seasonal variation, but there appeared to be a constant relation between firmness and acid level. In the final analysis, seasonal variation in the level of disorders was mainly related to differences in mean fruit size and when the size factor was held constant between seasons the differences remaining were relatively small. In the case of pit, some of these remaining differences could be accounted for by differences in relative maturity but in the case of breakdown, relative incidence between seasons was not related to relative maturity. There was an association of early blossoming with low incidence of pit and breakdown independent of later differences in seasonal climate. The results support the theory that low temperatures in the months prior to harvest increased susceptibility to breakdown.
Fertility and productivity of a podzolic soil as influenced by subterranean clover (Trifolium subterraneum L.) and superphosphate.
Authors: Donald CM , Williams CH
Published: November 2004

A survey was made of the influence of the use of superphosphate and subterranean clover (Trifolium subterraneum L.) on podzolic soils formed on granodiorite in the Crookwell district of New South Wales (average rainfall, 32.7 in. per annum). Forty-four paddocks were sampled; they varied from untreated native pasture to paddocks which had been for 26 years continuously under clover and which had received a total of 13 cwt of superphosphate per acre. In all instances there had been no cultivation during treatment, and the land use mas uniformly one of sheep raising, principally for wool but with some emphasis on fat lamb production on highly improved pastures. Criteria used in this study were the changes in yield and botanical composition of the pasture, changes or trends in the chemical composition of the 0-4 in. depth of soil, and the yield of oats produced by each of the soils in pot culture with varying superimposed applications of phosphorus, sulphur, and nitrogen. The native pasture species disappear under the competition by subterranean clover, which gives a fourfold increase in the yield of pasture. Within the limits of experimental error, the phosphorus and sulphur applied as superphosphate, even that applied many years previously, can be accounted for in the surface 4 in. of soil. Losses by removal in wool and carcases are small. The added phosphorus is present in approximately equal amounts as organic phosphorus and readily extractable inorganic phosphorus. The applied sulphur appears to become a part of the organic complex. Eighty-five pounds of nitrogen has been added in the surface 4 in. of soil by rhizobial activity for each hundredweight of superphosphate applied per acre. Initially the most acute deficiencies affecting plant growth on these soils are those of phosphorus and nitrogen, with a less pronounced deficiency of sulphur. After a period of several years of superphosphate and clover, each of these deficiencies is much reduced, the order of the intensity of deficiencies then being nitrogen, sulphur, and phosphorus. Soil pH falls with superphosphate application at the rate of about 0.06 units per hundredweight of fertilizer per acre, but may reach an equilibrium value at about 5.1. This could be due to the increase in exchange capacity of the soil as a result of the increase in organic matter. A field experiment on two sites also indicated the increase in fertility under subterranean clover pasture and demonstrated the capacity of the improved soils to produce a satisfactory field crop of oats.
The value of production from a clipped measured area as an index of fleece weight.
Authors: Morley FHW , Lockart LW , Davis EC
Published: November 2004

The correlation between greasy wool production per unit area, obtained by clipping and measuring an area of about 100 cm² on the midside, and greasy fleece weight at shearing was about 0.58. Wool production from such an area over periods of 7½ or 3½ months was almost as useful as production for 11 months for predicting greasy fleece weight. The multiple correlation coefficient between greasy fleece weight as the dependant variable and production per unit area and 11-months' body weight was 0.79 in 66 rams and 0.71 in 82 ewes. The inclusion of fold score did not improve prediction appreciably. The equation W = P/110 + B1 /12 may be used to predict greasy fleece weight (lb), W, where P is production over 11 months of greasy wool (mg/cm²) and B1 is 11-months' body weight (Ib). A table of this function is included so that values may be read directly. The technique may be a useful aid to selection of Merino sheep if recording of actual fleece weights is difficult or impossible. Nevertheless it should not be regarded as more than a moderately accurate substitute for actual fleece-weighing.
Changes in capacity of the udder of the dairy cow during the course of lactation.
Authors: Turner HG
Published: November 2004

Seven cows were each milked at a variety of intervals between milkings a t each of several stages of lactation, intervals being long enough for maximum attainable yields to be approximated. The udder was emptied thoroughly at the beginning and end of each interval with the aid of injections of posterior pituitary extract. Intra-mammary pressure was estimated at. each milking. Net capacity of the udder, as measured by maximum yield, declined during lactation in proportion to the concurrent decline in daily yield, so that any given long interval between milkings reduced yield to almost the same degree in late lactation as in early lactation. The decline in maximum yield or "physiological capacity" was contributed to jointly by decline in 'physical capacity' (volume contained at given intra-mammary pressure) and decline in maximum pressure or secretion pressure. In early lactation, decline in secretion pressure contributed most to decline in physiological capacity, loss of physical capacity becoming important only in late lactation. It appeared that high rate of physical involution was associated with low functional activity of secretory tissue, as measured by secretion pressure, rather than with advanced lactation per se. It is postulated that the physical and functional components of physiological capacity are paralleled by physical and functional components of daily yield, namely, amount of secretory tissue and secretion rate per unit of tissue. Accordingly, decline in secretory intensity contributes primarily to early decline in daily yield, loss of secretory tissue becoming important in late lactation or in cows in which functional activity of secretory tissue is low. Cows appear to differ in the relative contributions of mammary development and functional activity to lactational performance. The pattern and course of involution during lactation may be partly determined by these initial differences. The effect of length of interval between milkings upon secretion is discussed, with emphasis on the difference between immediate and long-term effects. It is pointed out that differences between cows in sensitivity of secretion to long intervals are morphologically rather than functionally determined.
Studies in the ecology of the riverine plain. II. Plant-soil relationships in three semi-arid grasslands
Authors: Williams OB
Published: November 2004

An experimental area on the semi-arid Riverine Plain originally supported Eucalyptus savannah woodland on sandy loams, Acacia-Atriplex dry scrub on clay loams, and Atriplex saltbush on light clays. Each of these communities has been replaced by a disclimax grassland. The species composition of the grassland is influenced by the soils. Differences in topography and texture are the main factors which affect the redistribution of rainfall. Soil permeability and subsoil structure are also important. The water regime of the soils over a 3-year period is measured in detail and the available moisture is estimated.
Studies in citrus nutrition. 2. Phosphorus deficiency and fruit quality
Authors: Bouma D
Published: November 2004

The effects of four cultural treatments and four nitrogen levels on fruit quality, percentage leaf phosphorus, and percentage leaf nitrogen in an experimental citrus orchard are presented. In general, the trees in the tilled treatments, which receive some superphosphate to secure a good growth of the winter cover crop, produce fruit of better quality than those in the notillage treatments. Increasing levels of nitrogen supply in the latter cause a marked decrease in fruit quality. This effect is associated with a decrease in leaf phosphorus in these treatments. Analyses of soils in the different cultural treatments point also to an unfavourable phosphorus status for the no-tillage treatments. A comparison with earlier results in this experiment indicates that fruit quality, particularly in the no-tillage treatments, is deteriorating. This progressive decline is shown to be related to a deterioration in the phosphorus status of the trees in these treatments. Highly significant correlations are reported between fruit quality indices and leaf phosphorus content. Less significant correlations were established with readily available soil phosphorus. These correlations were established in a survey of selected orchards in the Murrumbidgee Irrigation Areas, and similar correlations were obtained for the experimental orchard.
The effect of cold treatment on mutation in Drosophila melanogaster
Authors: Rendel JM , Sheldon BL
Published: November 2004

The effect of cold shocks of various kinds on the mutation rate of Drosophila is reported. No effects on mutation rate were found.
Genetic parameters asociated with characters affecting egg production in the domestic fowl. II. Heritability of egg production for two part-annual periods of measurement and the genetic correlation between them
Authors: Morris JA
Published: November 2004

Estimates of important genetic parameters have been obtained from an experimental flock using data collected over a period of 3 years. A total of 1784 progeny, obtained from 42 sires and 383 dams, supplied records for analysis. The information was mainly extracted using the analysis of variance and covariance from which estimates of genetic variance and covariance were obtained. Pooling the results within years and, where applicable, within breeding groups, estimates of heritability were obtained as follows: Production Index: part period, 32 per cent.; 72 weeks, 31 per cent. Survivor Index: part period, 33 per cent.; 72 weeks, 33 per cent. The low mortality rate should be borne in mind when comparing the estimates for the Production Index with those obtained by other workers. The estimated genetic correlation between the Production Index for these two periods was 0.72. The magnitude of the heritability estimates indicates the presence of a considerable amount of additive genetic variation. The proportion of this type of genetic variation has probably been increased by the minimizing of environmental variation effected by the randomization of birds over the housing space and, in the case of the part period of recording, by the corrections applied for hatching date influence. Early selection, based on partial records, has been shown to be approximately 1½ times as effective in producing genetic improvement as selection based on the full production.
Effects of flood irrigation and plant growth on two riverine soils
Authors: Barley KP , Tisdall AL
Published: November 2004

Two soils which contained significant proportions of exchangeable sodium were frequently irrigated during summer with water of low electrolyte content. When all vegetation was removed the soils became very unstable in water. When the natural vegetation was left intact the stability and structure of the soils did not deteriorate despite frequent irrigation. When the amount of vegetation was increased by sowing Rhodes grass (Chloris gayana Kunth) and supplying nitrogen and phosphorus the stability of the soil increased. After 8 years' growth of Rhodes grass the top inch of soil contained 30–40 per cent. of water-stable aggregates greater than 1 mm in diameter, compared with a content of 10–20 per cent. in virgin soil. Thus, the protective effect of the organic matter added to the soil by plant growth more than compensated for aggregate disruption caused by flood wetting or by a reduction in electrolyte content of the soil solution.
The breed structure and genetic analysis of the pedigree cattle breeds in Australia
Authors: Barker JSF
Published: November 2004

Barker (1957) discussed the influence of imported animals in the development of the pedigree Jersey breed in Australia. Random four-line pedigrees were drawn back either to a foundation animal (one present in Australia in 1900) or to an animal imported since 1900. The proportion of lines tracing back to each of these (equivalent to the genetic contribution) was determined for each of five samples of pedigrees. However, in this calculation, all four lines were used. This was incorrect as the pedigrees were drawn out by the method of Robertson and Mason (1954), in which one line was drawn back at random on each side of the pedigree and at each generation in the line both sire and dam were written down, though the line was only carried back through one of them. Therefore only those two lines which have actually been followed through should be used in an analysis of influence of importations. The analysis has been repeated on the same pedigrees as previously, and the correct results are shown in Figure 1. Imported animals have been more important in this breed's development than the original analysis showed. The influence of foundation stock declined rapidly until the 1928 sample, and has been declining at a slower rate since then. In the 1950 sample, the genetic contribution of foundation stock was only 14.76 per cent., while the following were the genetic contributions of animals imported since the date stated : From importations since 1940 2.50 per cent. From importations since 1930 29.25 per cent. From importations since 1920 44.76 per cent. From importations since 1910 68.50 per cent. From importations since 1900 85.25 per cent. Animals imported between 1900 and 1919 still have a large influence on the breed (a 40 per cent. genetic contribution to the 1950 sample), but their influence is declining. Animals imported since 1920 are still showing an increasing genetic contribution.
Frozen section technique for sheep skin
Authors: Nay T , Bathgate JA , Beeston J
Published: November 2004

A new simplified technique for obtaining histological sections of sheep and cattle skin is described, with details of the freezing microtome necessary for the technique.
Some factors affecting the solubility of phosphates during the microbial decomposition of plant material
Authors: Bromfield SM
Published: November 2004

Subterranean clover (Trifolium subterraneum L.) was decomposed under various conditions of incubation. Changes in the solubility of various phosphates and in pH were measured during the decomposition of this organic matter. Ferric phosphate and di- and tricalcium phosphates became more soluble when the clover was submerged and incubated under air or under nitrogen. Nauru rock phosphate and aluminium phosphate were not dissolved under these conditions. Ferric phosphate was not dissolved during incubation under well-aerated, moist conditions; it became more soluble as the degree of aeration of the mixture decreased and as the amount of clover, ferric phosphate, or water in the system increased. Ferric phosphate was dissolved by submerged clover in the presence of iron and aluminium oxides, but less phosphate and relatively more iron was in solution, owing to adsorption of the phosphate on the oxides. Bentonite did not decrease the solubility of ferric phosphate under similar conditions; however, calcium carbonate and kaolin caused a small decrease in solubility when added in large amounts. The pH of submerged clover incubated under nitrogen decreased from about 6.0 to between 5.0 and 4.5 and remained at this level; when incubated under air the pH was initially the same as under nitrogen but then rapidly increased to values as high as 8.5 During decomposition under well-aerated, moist conditions the pH steadily increased from 6.0 to 8.5.
Selective consumption of dry pasture by sheep as affected by spraying with urea or molasses or both
Authors: Willoughby WN , Axelsen A
Published: November 2004

Spraying low quality dry pasture with urea or molasses, or both, increased its consumption by sheep. This caused a more rapid reduction of the preferred components in the pasture. As a result they were earlier eliminated from the intake, their place being taken by the initially lion-preferred components. Spraying therefore affected the intake in three ways: it provided a supplement, it altered the quantity of plant intake, and it increased or decreased its quality, depending on whether the non-preferred components were higher or lower than the preferred in value. The overall effect was a reduction in sheep liveweight loss, but the likelihood of such an advantage in other circumstances is discussed. It is suggested that favourable animal response from the use of supplements to pasture car1 be expected only where any induced decrease in the quality of pasture intake 1s more than compensated for by other beneficla1 consequences of the supplement.
Effects of soil surface sealing on the growth of subterranean clover (Trifolium subterraneum L.) in pot culture.
Authors: Millington RJ
Published: November 2004

Root growth of Trifolium subterraneum L. (var. Bacchus Marsh) in pot culture was substantially reduced when the available soil-surface pore space was reduced to 0.06 c.c. per c.c. Top growth was also reduced. Measurements of oxygen concentration in the soil atmosphere showed that both sealing of the soil surface and sowing at high density depressed oxygen concentrations in the soil. It is suggested that the available pore space at the soil surface limited gas exchange, resulting in a depression of both the quantity of respiring root tissue and the resultant oxygen concentrations. The amount of root material present at any time is a function of sowing density and may further modify the response to sealing of the soil surface.
Pre-natal growth in Romney x Southdown cross and Australian Merino sheep. I. Introduction and external growth patterns in the two breeds
Authors: Stephenson SK , Lambourne LJ
Published: November 2004

An investigation has been made of vveight and length changes with age in Merino, and Romney X Southdown cross, foetuses. This breed difference had no effect on growth in length, but at the same age and body length the Romney X Southdown cross produced the heavier foetus. It appears probable, therefore, that the genetic effects (whether primary or through maternal influences) controlling this difference alter the muscle size and weight, the bone thickness, and also possibly the weight of the viscera, but do not affect the increase in length of the skeleton.
Sheep faeces in relation to the phosphorus cycle under pastures
Authors: Bromfield SM
Published: November 2004

Faeces from sheep grazing naturalDanthonia pastures and improved subterranean clover pastures have been analysed for total phosphorus and inorganic phosphate over a period of 2 years. Both total and inorganic phosphorus contents (milligrams P per gram) varied widely with type of pasture and with season. The variation in organic phosphorus content (by difference) remained, relative to total phosphorus, fairly constant throughout. Total phosphorus content varied from 1.8 to 17 mg P/g whilst organic phosphorus varied from 1.5 to 4.0 mg P/g. Sheep grazing the improved pastures voided approximately 2.5–3 lb P as inorganic phosphate and 0.5–0.75 lb P as organic phosphorus per sheep per year. The inorganic phosphate was readily soluble in acid but not in water and was readily available to wheat grown in pot culture. The organic phosphorus was not readily available to plants and was not rapidly mineralized to inorganic phosphate. The contribution faecal phosphorus makes to the nutrition of pastures and to the reserve of soil organic phosphorus is briefly discussed.
Seasonal variation in the reactivity to oestrogen of the ovariectomized ewe
Authors: Reardon TF , Robinson TJ
Published: November 2004

Fifteen tests carried out at an average interval of 4 weeks for 14 months showed an annual rhythm in the proportion of spayed crossbred ewes which exhibited oestrus after an injection of 15.6 µg oestradiol benzoate (ODB) following a 12 day period of progesterone treatment. Reactivity was highest in late summer and early autumn and lowest in winter and early spring. The periods of minimum reactivity coincided with the periods of low environmental temperatures and low body weights. The significance of the annual rhythm is discussed with particular relation to the phenomenon of "silent oestrus". No similar rhythm was detected in the 7-aginal response to oestrogen.
A comparison of White Leghorns, Australorps, and their reciprocal crosses
Authors: Beilharz RG , McDonald MW
Published: November 2004

Six hundred pullets comprising White Leghorns, Australorps, and their reciprocal crosses were compared in several commercial characters in cages and housed intensively on litter, until 500 days old. The pullets were produced from matings in which purebred sires left pure and crossbred half-sib progeny. Age at first egg, survivors' production, and hen-housed average production showed a considerable response to hybrid vigour. The reciprocal crosses were not significantly different. Both were consistently though not significantly better than White Leghorns and much better than Australorps in these three characters. Breed of dam had a large effect on mortality during the laying period. All other variables had insignificant effects. Breed of sire had the greatest effect on final body weight. Dams within breed also exerted a significant effect. Birds in cages wore heavier and laid more eggs than birds on litter.
The susceptibility of hay species to mechanical damage. II. Effects of moisture content and variety
Authors: Shepherd W
Published: November 2004

Separate effects of leaf and petiole or stem moisture contents on the susceptibility of hay species to mechanical damage during field curing and storage have been investigated. Three legume species were considered: lucerne (Medicago sativa L.), white clover (Trifolium repens L.), and subterranean clover (T. subterraneum L.). Several types of damage contributed to mechanical loss. The most important over the hay moisture content ranges normally encountered during field curing and storage were the breaking up of individual leaflets, fracture at leaflet–petiole junctions, fracture of petioles, and, with lucerne, fracture of side branch stems. Leaf, petiole, and stem moistures: either separately or jointly, affected the amount of each type. Most serious losses were from the leaf portion, but under some conditions up to 25% of the shattered material petiole and stem. The amount of leaf loss was determined largely by the leaf moisture content, but under some conditions more than half the leaf loss resulted from petiole or stem fracture, which was virtually independent of leaf moisture content. Individual plants within varieties and varieties within species differed in susceptibility to the various types of damage. Differences appeared to be inherent properties of the plants or varieties, and may be considered as potentially available for incorporation into standard varieties of hay species by selection or breeding. Overall reductions in susceptibility thus available were large, e.g. at least 46% with lucerne.
Bacterial wilt of potatoes. I. Field symptoms of the disease and studies on the causal organism, Pseudomonas solanacearum variety asiaticum
Authors: Harrison DE
Published: November 2004

By comparison with Kew South Wales and Rhodesian strains of Pseudomonas solanacearum, and a Canadian culture of Corynebacterium sepedonicum, it has been shown that the causal organism of bacterial wilt of potatoes in Victoria is a strain of Ps. Solanacearum, identified as variety asiaticum. This disease is a serious problem in the Koo-wee-rup and Gembrook areas. Many of the local isolates have no brown pigment, while others have a moderate degree of pigmentation, though much less than that of the Kew South Wales strains studied. Detailed symptoms of the disease are given; also the morphological, cultural, physiological, and pathogenic reactions compared with those of the other strains of Ps. Solanacearum studied. A serological study of these organisms will be presented in another paper.
Bacterial wilt of potatoes. II. Serological relationship of two strains of Pseudomonas solanacearum and a culture of Corynebacterium sepedonicum
Authors: Harrison DE , Freeman H
Published: November 2004

Antisera were prepared to Victorian and Rhodesian strains of Pseudomonas solanacearum, and to a culture of the ring rot organism, Corynebacterium sepedonicum, from Canada. It was found that the two strains of Ps. Solanacearum were similar, though distinct serologically, and each quite different from C. sepedonicum, although there was some serological affinity between the three organisms. The common agglutinins were absorbed to produce specific absorbed serum for each organism, the potential value of which is briefly discussed.
Metabolic activities of sheep erythrocytes. II. Formate metabolism
Authors: Leng RA , Annison EF
Published: November 2004

Whole sheep blood, washed erythrocytes, and haemolysates showed only a slight capacity to oxidize 14C-labelled formate, as measured by labelled carbon dioxide production. Considerable oxidation of formate by washed erythrocytes or haemolysates occurred in the presence of systems generating hydrogen peroxide enzymically or non-enzymically under aerobic conditions. In addition, methylene blue was found to stimulate markedly the aerobic oxidation of formate by erythrocytes and haemolysates, the effect being abolished under anaerobic conditions. The stimulatory effects of methylene blue and sulphydryl compounds were additive. Evidence was obtained that the effect of methylene blue was mediated through an enzyme which directly or indirectly gave rise to hydrogen peroxide, formate oxidation being achieved by a hydrogen peroxide-catalase complex. No evidence was obtained of formate incorporation into red cells.
Effect of clipping the coat on performance of calves in the field
Authors: Turner HG
Published: November 2004

The effect of keeping the coats of weaner calves clipped throughout the year has been measured at Rockhampton. Clipping lowered body temperatures and significantly increased growth rate during summer but reduced growth rate, slightly and not significantly, during winter. Individual animals differing in natural coat type differed more in growth rate than would be expected from the effect of the difference in coat cover alone. Differences in growth rate were more consistently related to inherent coat type than to coat cover. It is concluded that coat type is significant as insulation and as a factor affecting efficiency of evaporative cooling, but also as a character correlated with other physiological attributes, some of which are thermoregulatory and some not thermoregulatory. A sleek coat is therefore associated with some qualities which may be advantageous in a cool climate, but the manifold significance of coat type is expressed in a warm climate.
Studies on the carbohydrate metabolism of sheep. XV. The adrenal response to the climatic stresses of cold, wind, and rain
Authors: Reid RL
Published: November 2004

Plasma cortisol values were consistently elevated in undernourished pregnant ewes carrying a 7–10 months' fleece during 24–48 hr periods of climatic stress involving cold (2–3°C), moderate wind, and discontinuous or continuous heavy "rain". Increases in plasma cortisol were delayed, compared with the prompt response which occurs during emotional stress. Cold alone had no detectable effect; very high levels of plasma cortisol comparable with those often encountered during short periods of emotional stress were recorded only during periods of continuous "rain" of an intensity rarely, if ever, encountered in practice. Increases in blood glucose level during stress were considerably less in pregnant than in non-pregnant ewes; this is considered to reflect high foetal uptake of glucose. Overall, the stress was antiketogenic, probably owing to the ketolytic effect of increased blood glucose. In the latter part of the stress period, however, when plasma cortisol values were high, blood ketone levels increased in spite of elevated blood glucose; this ketogenic effect of stress is considered to be mediated by the adrenal cortex. The results are discussed in relation to current theories on the pathogenesis of ovine pregnancy toxaemia.
Continuous selection for egg production using short-term records
Authors: Morris JA
Published: November 2004

A closed flock of White Leghorn has been selected for high egg production, since 1947. Selection has always been based on performance achieved from date of first egg until May 31 (part-period test). Selection has been effective in providing gains of approximately three eggs per generation for the part-period and, at the end of the experiment, there is no evidence that the rate of gain has lessened. Total 72-weeks egg production increased during the earlier years of selection but seems to have plateaued subsequently. This leveling off of total production is due to a decline in performance for the period June 1 to 72 weeks of age. The magnitude of this decline is sufficient to offset the gain in the part-period. Annual selection differentials were calculated for the later years, and generally the realized selection differentials were the same size as that intended, which indicated that natural selection was not opposed to the direction of artificial selection. The estimates of heritability of part-period production index show no decline as a result of selection; the actual response observed during the last years of selection supports the contention of absence of such a decline. Although it cannot be statistically confirmed, there are indications that the genetic correlation between part-period and residual performance has decreased in value with the progression of selection. The size of the correlated decline in the residual production suggests not only a reduction in value of the genetic correlation but also a change of sign. The results obtained imply that continuous selection, based on egg production for the part-period, may be an unrewarding procedure; and that selection based on other characters, favourably correlated genetically with total production, might be more effective in providing genetic gain in total production.