bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection for seed retention in Phalaris tuberosa L.
Authors: McWilliam JR
Published: November 2004

Loss of seed from the maturing inflorescence (seed shattering) is common in grasses and constitutes a serious economic problem in many species. This paper reports the results of artificial selection to improve seed retention in Phalaris tuberosa, an important perennial grass in south-eastern Australia. A study of the factors controlling the loss of seed in this species has revealed that the seed lies free within the inflorescence at maturity, and its loss is promoted by the opening of the glumes. This in turn is influenced by the structure of the inflorescence. The highest seed retention has been found in plants with a short rigid inflorescence containing a large number of densely packed spikelets. Wide variation for seed retention exists between strains of P. tuberosa. The lowest value (25%) was found for natural ecotypes from Algeria and Morocco, and the highest for a selection from a strain of the Australian commercial type obtained from Argentina (81%). An estimate of the heritability for seed retention was high (0.92 ± 0.11), and most of the genetic variation appeared to be additive. There was a marked response to selection for high seed retention. With the Argentine variety as the base population, an increase of 29% in the average level of seed retention was achieved from the first cycle of selection. This level represents an increase of 60% by comparison with the widely grown commercial strain. The importance of high seed retention in relation to the economics of Phalaris seed production is briefly discussed.
Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson
Authors: Harrison DE
Published: November 2004

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.
The intial and residual effects of superphosphate and rock phosphate for sorghum on a lateritic red earth
Authors: Arndt W , McIntyre GA
Published: November 2004

The initial and residual effects of superphosphate and rock phosphate with sorghum were recorded on Tippera clay loam a lateritic red earth at Katherine, N.T. Both forms of phosphate were highly effective as initial broadcast applications and as residues. Initially, superphosphate was superior to rock phosphate on a weight per acre basis. For superphosphate the residual value left after 1 year was 50% of the initial value, and after 7 years about 8%. For rock phosphate the residual value after 7 years was about 66–70% of the initial value. The data have been extrapolated to give rough estimates of the value to complete exhaustion of the residue. These estimates suggest that for both superphosphate and rock phosphate, regular annual dressings of 1 cwt and of 2 cwt will give in the long run at least 80% and 95% respectively of the sorghum production possible with phosphate not limiting.
Studies on salt tolerance of sheep. V. The tolerance of sheep for mixtures of sodium chloride, sodium carbonate, and sodium bicarbonate in the drinking water
Authors: Peirce AW
Published: November 2004

Six groups, each of six sheep, were fed in pens for 15 months on a ration of chaffed lucerne and wheaten hays. One group was offered rain-water to drink, another group was offered 1.30% sodium chloride, whereas the others were offered one of the following mixtures of sodium chloride, carbonate, and bicarbonate: 1.26 + 0.015 + 0.025, 1.21 + 0.04 + 0.06, 1.12 + 0.08 + 0.13, and 0.95 + 0.161+ 0.25%. The intake of all saline solutions was higher than that of rain-water, ranging from 150% above for 1.30% sodium chloride to 60% above for the highest level of carbonates; the mean daily intakes for the entire experiment by the six groups were 2.6, 6.6, 4.8, 5.7, 5.8, and 4.2 l. respectively. The intake also increased in all groups with temperature, being 40–70% higher in the hottest months than in the coldest months.Weight increase was less from 6 months onward in the group receiving 1.30% sodium chloride, and was less at certain times only in the experiment in the groups receiving 0.04 or 0.10% carbonates, than in that receiving rain-water (control group). There were no differences in weight increase between the control group and the groups receiving the highest concentrations (0.21 and 0.41%) of carbonates The saline drinking waters had no effect on the concentrations of sodium, potassium, calcium, magnesium, or chloride in the blood plasma. The concentration of carbon dioxide was higher, for the last year of the experiment, in the blood of the control group, and, for approximately one-third of the experiment, in that of the group receiving the highest level of carbonates in its drinking water, than in that of any of the groups receiving lower levels of carbonates. There were differences in blood carbon dioxide on one occasion only between the control group and that receiving the highest level of carbonates. None of the solutions used in the experiment had any adverse effect on the general health, food consumption or wool production of the sheep.
Reaction of sheep to the consumption of Leucaena glauca Benth. and to its toxic principle mimosine
Authors: Hegarty MP , Schinckel PG , Court RD
Published: November 2004

Sheep on a sole diet of Leucaena glauca Benth. shed their fleece. The amino acid mimosine has been shown to be the depilatory agent. The depilatory effect of L. glauca was influenced by level and method of feeding. Small quantities of mimosine were excreted by sheep consuming L. glauca, but the major metabolite in the urine was identified as 3,4-dihydroxypyridine (DHP). It was established from the results of intravenous, intra-abomasal, and intraruminal administration of mimosine that sheep cannot detoxicate mimosine after absorption, but extensive degradation of mimosine to DHP takes place in the rumen. The absence of toxic symptoms in a sheep conditioned to L. glauca appeared to be due to increased detoxication in the rumen rather than to the development of an adaptive tolerance after absorption. The histological changes in the skin are described, and reasons for conflicting reports on the toxicity of L. glauca are discussed. A simple method for the isolation of mimosine from the seed of L. glauca is described in the Appendix.
The determination of mimosine and 3,4-dihydroxypyridine in biological material
Authors: Hegarty MP , Court RD , Thorne PM
Published: November 2004

A simple, specific method is described for the determination of mimosine and 3,4-dihydroxypyridine (DHP) in extracts of leaves and seeds of Leucaena glauca Benth. and in urine. Plant material is extracted with cold 0.1 N hydrochloric acid, and interfering substances are removed by chromatography on a cation-exchange resin. Organic cations are displaced from the resin with 2N ammonium hydroxide and the concentrated eluate chromatographed in one direction with the use of mesityl oxide : formic acid : water (41 : 7 : 6 by volume). The spots of mimosine and DHP, revealed with a ferric chloride spray, are cut out and the colour fully developed and measured. Urines are analysed in the same way except for a preliminary hydrolysis of the conjugated DHP. The method is satisfactory for estimating amounts of mimosine and DHP in the range 10–160 µg applied to the paper. Recoveries of these substances added to various extracts and to urine have varied between 98–102%. Appreciable destruction of mimosine, with the formation of some DHP, occurred when fresh L. glauca leaves were dried even under mild conditions. In fresh material no loss of mimosine occurred when it was placed immediately in 0.1 N hydrochloric acid. The ready hydrolysis of mimosine to DHP by boiling 0. I N hydrochloric acid has been demonstrated for the first time.
Estimation of leaf area for clover and lucerne
Authors: Williams RF , Evans LT , Ludwig LJ
Published: November 2004

Photographic standards have been prepared for the estimation of leaf area in clover and lucerne (alfalfa). A wide range of leaf form is covered, and the standards can be used for many trifoliate legumes. The method is rapid and can be used on the intact plant.
Corrigendum - Comparative breed studies of beef cattle. II. Changes in size and shape
Authors: Tulloh NM , Maritz JS
Published: November 2004

A comparative growth study of changes in shape was made of Hereford, Aberdeen Angus, and beef Shorthorn cattle. In addition to recording body weight, 10 surface body measurements were made, at regular time intervals, on every animal in the experimental group. Changes and differences in shape were studied by examining the functional forms of the relationships between surface body measurements and body weight for every animal. The breed and sex differences presented in this paper have also been composed with a re-analysis of the limited data available from the literature, and in general the results are similar.
The relationship between live measurements and edible meat in Merino wethers
Authors: Tallis GM , Turner HN , Brown GH
Published: November 2004

Seventy-five Merino wethers of a medium Peppin strain were slaughtered at 7 months of age after a series of live measurements had been made, weights then being taken of carcass and of edible meat after boning out. Fat content was insufficient for trimming, and bone weight was obtained by difference. Weight of edible meat was highly correlated (0.95) with liveweight before slaughter, and the inclusion of any other measurement in a multiple correlation analysis failed to raise this value. Variation in bone weight contributed only 25% of the variation in carcass weight, and the ratio of meat to bone was positively correlated (0.54) with liveweight before slaughter. If total amount of edible meat is accepted as the criterion for meat production, liveweight before slaughter was a satisfactory predictor for these sheep. It is suggested that simplification of criteria along these lines is desirable to aid in the selection of sheep for meat production, though more work is required on sheep of other ages and other breeds.
Body composition in vivo. VI. The composition of ewes during prolonged undernutrition
Authors: Panaretto BA
Published: November 2004

Ten Border Leicester x Merino ewes were divided into two groups on the basis of a initial calculation of their body composition. Group 1 comprised a group of six moderately fat ewes (fat content < 25% body weight), and group 2 four very fat ewes (fat content >40% body weight). The ewes were undernourished by feeding progressively diminishing quantities of a mixture of lucerne chaff and oats (1:1) until group 1 had lost 38.7 and group 2 33.7% of their initial weight in 150–200 days. Feed intakes and wool growth of the sheep were recorded and calculations were made of the body composition in terms of total body water, fat, protein, and ash as undernutrition progressed. Thiocyanate spaces, haematocrit values, and plasma, blood, and red cell volumes were also measured. Generally the ewes in group 1 exhibited a starvation syndrome which was characterized by the gradual depletion of the fat and protein reserves of the body until fat reserves had been almost completely used. Thiocyanate spaces in these ewes expanded relative to body weight, and the circulatory parameters showed a progressive shrinkage of the red cell volume while plasma volume was maintained. The ewes in group 2 differed markedly in their reaction to undernutrition in that three out of the four passed, after a time, into a phase of inappetence and died while still in a very fat condition.
Isotopic studies on the uptake of nitrogen by pasture grasses. II. Uptake of fertilizer nitrogen by Rhodes grass in posts
Authors: Henzell EF , Martin AE , Ross PJ , Haydock KP
Published: November 2004

Nitrogen uptake by Rhodes grass was a linear function of the quantity of 15NH4N03 applied for rates up to the equivalent of 400 lb N/ac, but the proportion of fertilizer nitrogen recovered in the plants fell significantly when the rate was increased to 800 lb N/ac. A nitrogen pretreatment equivalent to 200 lb N/ac had relatively little effect on the uptake of 15NH4N03 by the grass, despite the fact that it almost doubled the weight of roots in the pots when the 15NH4N03 was first applied. Over the range 0–400 lb N/ac, 84.1%% of added total nitrogen and 75.5% of added 15N was taken up by plants that received no nitrogen fertilizer during the pretreatment phase, and 80.3% of added total nitrogen and 71.9% of added 15N was taken up by plants that received a pretreatment of 200 lb N/ac. Fertilizer nitrogen was distributed between tops and roots in the ratio (averaged for the two pretreatments) of 5.2 : 1 for total nitrogen and 4.5 : 1 for 15N; these ratios were constant over the range 0–400 lb N/ac and were not significantly different.
The digestion of food by the grazing sheep. III. The quantity of protein reaching the small intestine
Authors: Hogan JP
Published: November 2004

An estimate has been made of the intake of dietary nitrogen and of the amount of digesta nitrogen reaching the duodenum in sheep eating fresh feed. In grazing sheep consuming an estimated 17–63 g nitrogen/day. 15–40 g digesta nitrogen/day reached the duodenum. Sheep eating cut forage consumed 25–63 g nitrogen/day, and 19–60 g nitrogen/day passed through the pylorus. About 70% of the digesta nitrogen reached the duodenum in the form of bound amino acids.
A blue discoloration of fleece wool caused by a pigment of Pseudomonas indigofera
Authors: Mulcock AP , Horn PE , Shroff RV
Published: November 2004

Specimens of fleece discoloured blue have been collected from the South Island of New Zealand. The pigmentation was usually confined to a single band 1–3 cm wide, and the area affected on the sheep varied from less than 10 cm in diameter to the whole fleece. The colouring matter was present as discrete particles which adhered to the wool fibres and could be removed by washing with petroleum ether. The pigment was recovered from the solvent by centrifugation and was purified by chromatography on alumina. A bacterium producing a blue pigment was isolated from blue fleece wool. This bacterium was grown on agar, and the pigment it produced was shown to have similar properties to the one extracted from the fleece. The bacterium was identified as Pseudomonas indigofera.
The effect of density on the performance of individual plants in subterranean clover swards
Authors: Stern WR
Published: November 2004

A study was made of the growth of individual subterranean clover plants in pure cultures at 4, 16, and 36 plants dm-2. At 20 days there was no difference between plants in any of the treatments. By 41 days significant differences in root weight between densities had developed and these differences extended to top weights, branch numbers, and the rate of leaf formation as the experiment progressed. The effects on individual plants were essentially the outcome of competition for light. At all densities some plants continued to gain weight throughout the experiment while others were suppressed after an initial increase. As competition for light became more severe, variable leaf development led to increasing variation between plants. From 90 days onwards the coefficient of variation of individual top weights and root weights steadily increased at the two higher densities. Those plants that had their developing leaves heavily shaded for a period of time eventually died. The performance of individual plants is discussed in relation to the light microclimate. The experiment leads to the view that dominance and suppression are characteristic, in some degree, of all plant communities.
Survival studies with Rhizobium trifolii on seed of Trifolium incarnatum L. inoculated for aerial sowing
Authors: Hely FW
Published: November 2004

Several methods of clover seed inoculation were compared on a field scale, sowings of Trifolium incarnatum L. being made on the surface of tussock grass hill country. A three-step method of inoculation was significantly superior in respect of numbers of Rhizobium trifolii found in the seedling rhizosphere, nodulation of seedlings, and growth of plants. In studies conducted with this clover on commercial aerial sowings of seeds inoculated by the three-step method, 5 weeks elapsed before germinating rains fell. The findings were : (i) Under exceptionally dry conditions following aerial sowing, the inoculum and seed-coating material remained on the seeds; where the seeds were largely sheltered by grass tussocks the persistence of inoculum remained satisfactory (100,000 Rh. trifolii per seed) for 2 weeks and moderately satisfactory for a further 2 weeks.(ii) Where there was no rain for some weeks after sowing but the coating materials and most of the inoculum were removed by dew and frost, Rh. Trifolii of the applied type built up considerably in the adjacent soils and persisted fairly well. (iii) Small falls of rain after sowing, although inadequate for seed germination, appeared to be beneficial in accelerating the transfer of coating materials and inoculum to the soil, where considerable development of Rh. Trifolii populations occurred. These new populations were sufficiently maintained to give good colonization of rhizospheres and nodulation of seedlings which became established following germinating rains 5 weeks after sowing. In spite of this delay and the consequent low temperature conditions, the great majority of established clover plants had nodules promptly formed by the applied bacterial strain under all conditions studied. Application of the three-step method of inoculation to this clover demonstrated that: (i) A delay of some days between inoculation and sowing was permissible. (ii) A large number of Rh. Trifolii and some pellet constituents were carried into the soil at places where seeds sown from the air were likely to germinate. (iii) A persistent inoculum remained loosely attached to the seed coats.
The role of temperature in the development of blue mould (Peronospora tabacina Adam) disease in tobacco seedlings. I. In leaves
Authors: Hill AV , Green S
Published: November 2004

In tests over a wide range of temperature conditions the number of days from inoculation of plants of cv. Virginia Gold with conidia of Peronospora tabacina to appearance of blue mould symptoms in leaves varied from 4 to 12 days with conidia of strain APT1 and from 5 to 15 days with strain APT2. It was 4 to 14 days with strain APT2 on plants of cv. SO1. Initial death of leaves of cv. Virginia Gold occurred at 5–6 days after inoculation with APT1 but 3–4 days later when similar plants or cv. SO1 were inoculated with APT2. For each strain there was a strong trend toward similar leaf loss, and similar progressive development of leaf loss in treatments with the same night temperatures. For both strains, leaf losses developed most rapidly and were most severe at night temperatures of 16–24°C. The relatively slow development of APT2, except over a narrow range of temperatures, would limit its capacity for competing with APT1 and for producing epiphytotics.
The dispersal of colidia of Sclerotinia fructicola (Wint.) Rehm.
Authors: Jenkins PT
Published: November 2004

The dispersal of conidia of Sclerotinia fructicola (Wint.) Rehm. was studied in a peach orchard and in the laboratory, with the use of traps for water-borne spores and an automatic volumetric spore trap. In the orchard, little aerial dispersal was detected by using a trap less than 10 ft from the nearest trees, but large numbers of spores were dispersed by rain falling on sporulating blossoms. In the laboratory, splash droplets from a drop of water falling onto a sporulating fruit or glass slide dusted with conidia were recorded at distances of up to 36 cm. More than two-thirds of the droplets contained spores, the numbers ranging from 3 to more than 7000 per droplet. Aerial dispersal was detected in the laboratory when sporulating peach fruits were placed 3 ft from the volumetric trap. Dispersal was greatest at minimum humidities and maximum air temperatures. The results of the experiments suggest that splash dispersal is more important than aerial dispersal of conidia of S. fructicola in the epidemiology of brown rot of stone fruits.
The effect of seed potassium on emergence and root developent of seedlings in potassium-deficient sand
Authors: Ozanne PG , Asher CJ
Published: November 2004

Seeds of silver grass and cape-weed contained so little potassium that the roots of these species could only penetrate a highly potassium-deficient sand to a depth of 3 or 4 cm. By contrast, lupin seeds contained enough potassium to allow root development to a depth of at least 90 cm. The behaviour of other species studied was intermediate between these extremes. With seeds low in total potassium, evidence was obtained of a beneficial effect of applied potassium on seedling emergence. A study of seeds varying in total potassium from 1 µg to more than 20,000 µg showed that most of the variation in total seed potassium was due to variation in seed size, potassium concentration in the seeds being relatively unimportant. The possibility of improving the field establishment of seedlings on potassium deficient soils by increasing the potassium content of the seeds is discussed.
The reaction of calves to helminth infection under natural grazing conditions
Authors: Durie PH , Elek P
Published: November 2004

The reaction to helminth infection was studied in calves grazing natural pasture in an area of south-eastern Queensland. Calves raised worm-free were exposed each month to natural infections with Cooperia punctata, C. pectinata, Trichostrongylus axei, Haemonchus placei, and Oesophagostomum radiatum. The observations extended over 2 years. Calves first exposed during the months of higher rainfall (December–April) suffered a mortality of 93%, whereas the mortality was 63% in those placed on the pasture during the drier months. Weight loss and death of calves during the first 8 weeks' grazing was associated with a pasture larval contamination of more than 50 larvae of the above species per sq yd. Evidence was obtained that O. radiatum was the main pathogen during the experimental period, and egg counts of this species greater than 380 eggs per gram of faeces were associated with clinical signs of infection. Some calves, which were initially exposed to infection shortly after seasonal rains had fallen, acquired the highest worm burdens and survived for less than 10 weeks. Calves which survived for 11–22 weeks were on a better than average pasture, and were first exposed to infection at least 4 weeks after suitable rains when the larval population had commenced to decline. These calves acquired approximately half the worm burden recorded for the calves which did not survive beyond 10 weeks. Calves surviving for longer than 22 weeks were first exposed to infection 2–3 months after seasonal rains, and showed a mean maximum O. radiatum egg count less than two-thirds of that recorded for the animals which survived for 11–22 weeks. Body weights in the group surviving for more than 22 weeks did not increase until after 20 weeks, when the egg counts had decreased to consistently low levels. Infective larvae of O. radiatum ingested after the first week did not contribute significantly to the adult population found at necropsy. Despite the inability of these larvae to complete their development, pathogenic effects of the continuous intake continued until about the 20th week. No evidence was found that the presence of haemagglutinating and complement fixing antibodies was correlated with the survival of calves.
Effect of inoculum spore load, length of infection period, and leaf washing on occurrence of Peronospora tabacina Adam, (blue mould) of tobacco
Authors: Hill AV
Published: November 2004

Leaves of tobacco plants cv. Virginia Gold were spray-inoculated with different concentrations of spores of Peronospora tabacina strain APT1 and kept wet for 2 to 16 hr. Incubation period and occurrence of the disease on leaves were related to spore concentration, length of the infection period, temperature, and leaf position. The length of the incubation period increased from approximately 3 to 8 days with decrease in spore number. There was a similar increase with decrease in the length of the infection period and with low temperatures. The number of disease lesions increased with spore number in the inoculum and with increase in the length of the infection period up to 8 hr; it was about 100% higher on washed than on unwashed leaves. All leaves of washed plants had the same number of lesions but with unwashed plants, the lowest leaf had the most lesions and the uppermost the least. In a limited series of experiments with APT2 on cv. Virginia Gold and cv. Sol, the results were similar to those reported for APT1. The host–pathogen reaction was modified by spore load and temperature, the result being a range of symptoms; this indicates the need for caution in the use of symptoms as a means for distinguishing between different strains of the pathogen and between levels of resistance. High spore concentrations and infection periods of 4 hr or longer were necessary for extensive occurrence of the pathogen in leaves.
Water metabolism of Merino sheep shorn during summer
Authors: Macfarlane WV , Howard B , Morris RJH
Published: November 2004

Ten Merino wethers in the dry subtropical region of "Gilruth Plains", Cunnamulla, Qld., were shorn in November during a period of sunshine with maximum temperatures between 36 and 38°C. The content, distribution, and turnover of water were estimated before and after shearing. There was no significant change in total body water but the thiocyanate space increased by 12%, the plasma volume by 17%, and the plasma proteins were diluted by 17% after shearing. Water turnover rose from 81.5 to 159 ml/kg/24 hr. There was a correlation (v = 0.68) between the increase in respiratory rate which took place when the sheep were standing in the sun and the increase in water turnover during the same period. It is estimated that an average increment of 1550 kcal/24 hr in heat load from insolation occurred as a result of the removal of fleece during exposure to summer sun. The greater water turnover from evaporative cooling was associated with increased extracellular fluid space.
Soil fertility changes in a red-brown earth under irrigated pastures. II. Changes in phosphorus
Authors: Rixon AJ
Published: November 2004

Changes in phosphorus applied as superphosphate to irrigated pastures on a red-brown earth were studied for a 4 year period commencing 1 year after the establishment of the pastures. The pastures consisted of Wimmera ryegrass (Lolium rigidum Gaud.), perennial ryegrass (L. perenne L.), subterranean clover (Trifolium subterraneum L.), and white clover (T. repens L.). Measurements of phosphorus fractions were made on the 0–3 in. soil horizon over this period and, for the final 2 years, on the organic matter layer (mat) which was present on the soil surface under all pastures. The mat was shown to be an important accumulation site for organic phosphorus, as well as for inorganic phosphorus which accumulates from interception of broadcast applications of superphosphate. Of the 155 lb phosphorus per acre added as fertilizer, 82–100% was accounted for principally as increases in the acetic acid-soluble fraction or as organic phosphorus. There were no significant changes in the inorganic phosphorus fraction soluble in sodium hydroxide. It was concluded that the amount of phosphorus converted to the organic form will determine the level for maintenance applications of phosphorus on the irrigated pastures.
Studies on the survival of the non-parasitic stages of the cattle tick Boophilus microplus in three climatically dissimilar districts of North Queensland
Authors: Harley KLS
Published: November 2004

Survival of the non-parasitic stages of the cattle tick, Boophilus microplus (Canestrini), has been investigated over a period of 5 years in 25, 40, and 80 in. rainfall districts of north Queensland. Engorged ticks were exposed regularly in field plots and in Stevenson screens, and the times of egg hatchmg (prehatch period) and periods of survival of the larvae were observed. The prehatch period in the three districts followed the same pattern and was related to seasonal temperature changes, varying from less than 4 weeks in midsummer to over 13 weeks in midwinter. A relationship between minimum prehatch period and mean air temperature for ticks exposed in screens was established, but the data from ticks exposed in the field were too variable to establish a relationship between prehatch periods and soil temperatures. Hatching was recorded in every month of the year from all districts, but during the driest months in the 25 in. rainfall areas many ticks in exposed situations failed to reproduce. Larval survival and total longevity also followed a similar pattern in all districts. The longest survival periods were recorded for the progeny of ticks exposed late in the wet season from March to April, and the shortest survival periods for the progeny of ticks exposed during the dry season from August to September. Mean maximum total longevity for ticks exposed in field plots in the 25 in. rainfall district varied from 10 to 22 weeks, in the 40 in. rainfall district from 14 to 22 weeks, and in the 80 in. rainfall district from 15 to 26 weeks. The data on prehatch and survival periods are a suitable basis for formulating recommendations for tick control by pasture spelling and planned dipping.
The success or failure of strains of Trifolium subterraneum L. in a Mediterranean environment
Authors: Rossiter RC
Published: November 2004

Five field experiments, three of which extended over a 9-year period, are described. Success or failure was assessed on a relative basis in three competitive situations, in each of which associated volunteer annuals were present. These situations were: (1) single-strain swards, (2) single-strain swards in association with an "indicator" strain at low initial density, and (3) mixed swards of several strains. The results support the hypothesis that the main determinant of success or failure of a strain of T. subterraneum in a mixed pasture is the seed-producing capacity of that strain when grown in ungrazed pure swards. More importantly, the form of the relationship between relative success and seed yield was shown to differ for each of the three competitive situations. Relative success was also related to "maturity grading" (a measure of earliness of flowering) since seed yield and maturity grading were themselves strongly related. However, partial regression analysis indicated no significant effects of maturity grading independent of seed yield. The importance of three further possible determinants of success or failure – seed size, petiole length, and hardseededness – is discussed. No evidence for their importance is adduced, except in the case of hardseededness under low rainfall conditions. Natural selection in multiple-strain swards is also discussed, and the need for further studies on factors associated with success or failure of closely related genotypes is emphasized.
Selection from one of several populations
Authors: James JW
Published: November 2004

Two methods of choosing foundation stock for an animal-breeding programme are compared: selection within one population (chosen in the hope or belief that it is genetically superior) or selection within each of several populations. It is tentatively concluded that selection from several populations is likely to provide the better foundation stock. This conclusion depends on the assumption that variation between populations in mean breeding value is not large relative to genetic variation within flocks, but evidence on this point is desirable. Doubling the number of populations from which selection is made will increase genetic gain by about one-quarter of the heritability multiplied by the phenotypic standard deviation.
Plant growth on a low calcium status solodic soil in a subtropical environment
Authors: Russell JS
Published: November 2004

The importance of calcium in legume growth and soil fertility in temperate regions is well known, but there is evidence that in tropical regions adequate legume growth may be obtained under conditions of low calcium status. These differences require further elucidation for a subtropical environment, particularly as both temperate and tropical species occur and climatic conditions are transitional between temperate and tropical regions. Large areas of solodic soils of very low calcium status occur in southern Queensland. Volunteer plant growth is poor and sparse. In considering the use of legume species to increase the amount of nitrogen in the soil–plant system the possible effect of low calcium status assumes importance. Investigations were carried out on a solodic soil from Tara, Trifolium repens L. and Phaseolus lathyroides L. being used as representative of temperate and tropical legumes respectively. Initial nutrient studies showed an extreme phosphorus deficiency. Even with adequate phosphorus supplied as sodium dihydrogen phosphate, however, yield of the temperate legume was poor. This was due to the existence of soil conditions which could be ameliorated by the application of calcium carbonate (lime). Interactions between legume species, nutrient elements, and lime were observed. Lime with zinc substantially increased the yield of T. repens. Smaller increases were obtained with P. lafhyroides; in the absence of zinc, lime depressed the yield of this species. The sulphur treatment decreased soil pH, but a positive lime=sulphur yield interaction was obtained. A copper deficiency in T. repens uncomplicated by lime interaction was found. There was no evidence of molybdenum deficiency or of a molybdenum-lime interaction. The beneficial effects of lime are considered to be associated with both calcium deficiency and mineral element toxicity. The possible effect of climatic factors on both zinc deficiency and aluminium toxicity in relation to temperate and tropical legumes is discussed. A range of 48 species and strains of temperate legumes also showed marked responses to lime on this solodic soil, although differences were observed between species and genera. The role of calcium in superphosphate and the multiplicity of effects associated with the use of this fertilizer emphasize the difficulty of interpreting field responses and of attributing response to any one factor.
Population suppression in the Queensland fruit fly, Dacus (Strumeta) Tryoni. II. Experiments on isolated populations in Western New South Wales
Authors: Bateman MA , Friend AH , Hampshire F
Published: November 2004

This is the second paper in a series describing experiments designed to investigate the potential usefulness of chemical lures for the suppression of isolated populations of the Queensland fruit fly. The experiments reported here were done in two consecutive years and involved 12 country towns in central and north-central New South Wales. Three of the towns were treated with a male-attractant plus an insecticide; three were treated with a general lure plus an insecticide; three others received a combination of both treatments; and the remaining three were left untreated for comparison. In the first year neither single treatment had any significant effects on the populations, while the double treatment achieved an acceptable level of control. In the second year the performances of both single treatments improved greatly, while the combined treatment gave excellent control. It is shown that isolated populations of fruit fly can be suppressed by these means.The implications of these results for future large-scale control of the Queensland fruit fly are discussed briefly. More complete discussion must await publication of further developments of this work, which will be reported in later papers in this series.
Nutritional status and intake regulation in sheep. V. Effects of intraruminal infusions of volatile fatty acids upon voluntary intake of roughage by sheep
Authors: Egan AR
Published: November 2004

Results of experiments with infusions of volatile fatty acids into the rumen reveal that the induced changes in voluntary intake of roughages are not immediate, and vary in extent between animals. Single infusions resulted in subsequent depressions of feed intake, these being only partly related to the amount of energy of the infused volatile fatty acids. When longer-term infusions were made, acetic acid in small quantities depressed feed intake more than did propionic, and propionic acid modified the effect of acetic when the two were given together. Also recorded is an observation that animals receiving a casein-supplemented roughage diet reduced their feed intake when casein was infused per duodenum over 14-day periods. Results are discussed in relation to an hypothesis of an indirect mechanism attempting to maintain or restore the original energy balance, but showing considerable delay or inertia and imprecision when observed on a day to day basis.
A disease of French beans (Phaseolus vulgaris L.) caused by subterranean clover stunt virus
Authors: Smith PR
Published: November 2004

A disease causing serious crop losses in early-sown French beans in the East Gippsland area of Victoria has been shown to be caused by subterranean clover stunt virus. The virus infected a wide range of leguminous plants and persisted through a moult of its principal vector, Aphis craccivora Koch. It was not seed-borne, nor was it mechanically transmissible. The field symptoms of the disease on French beans consisted of chlorosis and epinasty of leaves, the whole plant being markedly stunted with a reduction in the length of the internodes. These symptoms were reproduced in the glasshouse by aphid inoculation of the virus to French beans. However, the virus was recovered from both naturally infected and artificially inoculated beans with difficulty. In field tests, no cultivar of French bean tested was immune to the virus, although a high degree of tolerance was observed in the cultivars Red Mexican U.I.3, U.I.34, and U.I.37, and Pinto U.I.72 and U.I.78.
Effects of season, nutrition and hormone treatment on the fructose content of ram semen
Authors: Moule GR , Braden AWH , Mattner PE
Published: November 2004

A marked seasonal fluctuation was found over 2 years in the concentration of seminal fructose, and in the total amount per ejaculate, in Merino and Romney Marsh rams at pasture. Values were high in autumn, low in spring. No such fluctuation was observed in rams kept on a constant diet under a natural or a reversed annual light cycle; but when the energy intake of the rams was decreased by 30%, there was a sharp decline in the amount of fructose per ejaculate. In castrated rams the amount of fructose per ejaculate was linearly related to log (dose of injected testosterone). In entire rams injections of human chorionic gonadotrophin caused an increase in seminal fructose, but thyroxine injections were without effect. Stilboestrol injected at levels of 25 and 250 µg/day caused marked decreases in seminal fructose. Increasing the frequency of electro-ejaculation from once per 2 weeks to twice weekly caused an increase in seminal fructose.
General and specific combining ability in varieties of Leucaena leucocephala (Lam.) de wit
Authors: Gray SG
Published: November 2004

A diallel series of intervarietal crosses in Leucaena leucocephala was used to estimate general and specific combining ability for length of main stem and stem number in four varieties of contrasting growth habits. Reciprocals were not included. Significant differences were found between varieties for variation due to general combining ability, for both characters, and for variation due to specific combining ability for length of main stem, but not for stem number. Peru and Guatemala were superior to Hawaii and El Salvador in general combining ability for length of main stem. Peru and Hawaii were superior to El Salvador and Guatemala in general combining ability for stem number. Peru and El Salvador had much higher specific combining ability variances for length of main stem than Guatemala and Hawaii. An evaluation of parents and crosses based on F1 performance and the estimates of combining ability has been made, and compared with the subsequent performance of the crosses in later generations.
Assessment and integration of special purpose pastures
Authors: Myers LF
Published: November 2004

A model is used to examine methods of integrating two or more pasture types which have complementary growth rhythms. The model suggests the use of results from experimental stocking-rate sequences on each pasture to estimate the area to be allotted to each pasture type, the necessary animal movements, and the resulting animal productivity on a series of theoretical farms.
Chromosome number and morphology of some introduced Strylosanthes species
Authors: Cameron DF
Published: November 2004

Chromosome numbers have been determined for 19 accessions representing 10 species of Stylosanthes Sw. Diploids (2n = 20), tetraploids (2n = 40), and one hexaploid (2n = 60) have been found. There are differences in chromosome size and morphology. The significance of these differences in the evolution of the genus is discussed.
The movement of copper, molybdenum, and selenium in soils as indicated by radioactive isotopes
Authors: Jones GB , Belling GB
Published: November 2004

Radioactive isotopes of copper, molybdenum, and selenium have been applied to a number of soils in order to study the movement of these trace elements under the influence of various fertilizer treatments. With soils of moderate exchange capacity the copper remained near the surface following all fertilizer treatments and the equivalent of several years' rainfall. With light soils of low exchange capacity some penetration of copper occurred, especially following superphosphate and an aqueous extract of lucerne. With molybdenum in general a high proportion of this element was leached right through the soils, except in the case of the two laterite soils examined, where up to half of the molybdenum was retained near the surface. Selenium applied as sodium selenite was intermediate between the extremes illustrated by copper and molybdenum, in that a high proportion was retained by the calcareous soils but not necessarily at the surface. The lighter soils retained a much lower proportion of selenium.
Vital statistics for an experimental flock of Merino sheep. IV. Failure in conception and embryonic loss as causes of failure to lamb
Authors: Dolling CHS , Nicholson AD
Published: November 2004

Ewes which fail to lamb can be classified as failing to conceive (ENC) or conceiving but failing to carry at least one embryo to full term (ENE). Estimates of ENE have been made indirectly from mating and lambing records involving 2509 observations over 3 years in a flock of medium Peppin Merinos. Estimates of ENE and of individual embryo loss have been made directly from autopsies of 419 ewes in the same Peppin flock and in one of mixed strains. The indirect estimate of ENE (ewes served and expected to have conceived but failing to lamb, as a percentage of ewes joined) averaged 4.3% for ewes aged 1½–9½ years at joining. Two measures of early embryonic loss were obtained from the autopsies of ewes expected to have been pregnant for approximately 28 days: (i) Ewes predicted not to lamb, as a percentage of ewes expected to have conceived, gave an estimate of 2.8–3.9 % at 1½ years, and 10.1–12.0% at 8½–11½ years. (ii) By relating the number of active corpora lutea to the number of healthy embryos, the estimates of loss obtained were 4.7–5.8% for maidens and 18.6–20.6% for aged ewes. From approximately 28 days to term no significant foetal loss from resorption or abortion could be demonstrated by comparing autopsy predictions with observed performance in ewes proceeding to term, though a very small loss of one of a pair of twins may have occurred in ewes aged 1½ years. Ewes with two active corpora lutea suffered a significantly greater loss of embryos than did ewes with one. With the corpus luteum as the unit, the loss in maiden ewes was 20.0% with two corpora lutea and 2.9–4.1% with one, the corresponding figures for aged ewes being 34.7–36.1 and 9.0–11.5%. These differences are not evident with the ewe as the unit, as a ewe with two corpora lutea which had lost one embryo would remain in the group predicted to lamb. Estimates of ENE from autopsy were made on ewes selected from the complete flock because they had not returned to service. Estimates for the same ages on the complete flock were 3.6–4.5% for maiden and 8.7–10.2% for aged ewes. Calculations of ENC have been based on the estimate of ENE made here and on previously reported figures of the numbers of dry ewes per ewe joined and present at lambing. Ranges of ENC were 13.6–14.5% at 2 years, and 3.3–4.8% respectively. No identical twins were observed at autopsy, and there is no reason to believe that any would have been present at any earlier stage of pregnancy.
Pathological changes associated with Oesophagostomum columbianum infestations in sheep: Serum protein changes after first infestation
Authors: Dobson C
Published: November 2004

The serum proteins of worm-free crossbred lambs were found to vary over a period of 10 weeks. Infestation of these lambs with 2000 infective Oesophagostomum columbianum larvae also caused marked changes in various serum proteins separated by cellulose acetate electrophoresis. The total serum proteins of infested sheep remained static or decreased slightly over the period of observation. There was a marked hypoalbuminaemia (measured in grams per cent.) in the infested lambs. The α-globulin retained the same level as in the controls; this was attributed to compensatory synthesis to overcome the osmotic changes produced by albumin loss. The ß1-globulin decreased throughout infestations; both albumin and ß1-globulin could have been lost through inflammation of the alimentary tract. The ß2-globulin increased very greatly during infestation; this was attributed to an immunological response. The y-globulin level at first decreased, but after 10 days the level increased at a rate commensurate with that in the control lambs. This increase was also attributed to an immunological response.
Renal function in heifers
Authors: Campbell EA , White A
Published: November 2004

Glomerular filtration rate (GFR) (inulin clearance) has been studied in heifers which showed marked changes in weight over the test period. It is concluded that changes in GFR are not related to the weight of the animal, but are a characteristic of the animal. It is erroneous to use a standard weight as a common reference point for cattle. Creatinine/inulin clearance ratios were all found to be greater than unity.