bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of chemical extractions and continuous cropping to measure the potassium status of soils
Authors: Graley AM
Published: November 2004

Soil potassium, measured by simple chemical extractions, was compared with potassium availability assessed during continuous cropping of perennial ryegrass in pots, on 12 surface soils representing four Tasmanian soil groups. For three soil groups with mainly kaolinitic clay, potassium uptake by the plant (the main measure of potassium availability) was related to a decrease in the potassium extracted from the soil by boiling lM nitric acid during the experiment. The decrease in soil potassium extracted by repeated nitric acid digestions averaged 95% of the total potassium uptake. However, a large and rapid uptake from the illitic yellow podzolics was only partly assessable by chemical extractions. For all soils, much of the large amount of potassium taken up early was stored in the plant roots and transferred to the tops much later. Plant yields were related to exchangeable potassium only within soil groups; over most soils they were related to nitric acid-soluble potassium. Yield responses to added potassium usually occurred when exchangeable potassium became depleted to a critical level of 0.2–0.25 m-equiv./100 g or nitric acid-soluble potassium to 0.4–0.7 m-equiv./100 g. The critical level of potassium in ryegrass tops was 0.5–0.8%. On average nearly two-thirds of the potassium released from soils came from exchangeable sources. Potassium initially non-exchangeable was differentiated into quickly released 'intermediate' potassium and slowly released 'constant rate' potassium. Release of intermediate potassium predominated from the yellow podzolics and from one non-calcic brown soil with much randomly interstratified material in its clay.
The nutrition of ruminants grazing native and improved pastures. III.* Mineral composition of bones and selected organs from grazing cattle
Authors: Langlands JP , Cohen RDH
Published: November 2004

Hereford heifers grazed native pasture, native pasture which had been dressed with superphosphate, native pasture which had been dressed with superphosphate and oversown with white clover and native pasture which had been dressed with superphosphate and oversown with white clover and lotononis. The heifers were slaughtered after 12 months and the livers and kidneys were analysed for copper, zinc, molybdenum and manganese, the hearts for copper, zinc and manganese, and the livers for selenium. Samples of the spine, skull and tail, ribs, pelvis and scapula, long bones and soft tissues were analysed separately for nitrogen, fat, ash, calcium, phosphorus, magnesium, zinc and sodium. There were significant increases in the copper, zinc, and manganese contents of the kidneys when pastures were improved, but these differences were not evident in the liver or heart or in the molybdenum contents of the liver and kidney. Selenium content of the liver declined. The concentrations of phosphorus, calcium and magnesium in the fat-free dry matter of the spine, skull and tail, and ribs were less for cattle grazing native than for those grazing the other pastures. Differences in the composition of the pelvis and scapula, and long bones were not significant.

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*Part 11, Aust. J. Agric. Res., 29: 875 (1978).
Rapeseed adaptation in northern New South Wales. III.* Yield, yield components and grain quality of Brassica campestris and Brassica napus in relation to planting date
Authors: Hodgson AS
Published: November 2004

The response of grain yield, yield components and grain quality of B. campestris and B. napus cultivars to planting date for two seasons at three locations from the north-western slopes to the northern tablelands of New South Wales are reported. The planting date that gave the highest yield varied between species and locations. The two species differed in the way yield components compensated for each other. For example, in B. campestris, yield variation was related to plant population and individual seed weight; in B. napus, both the number of pods per plant and the number of seeds per pod influenced yield. The oil content was highest in early plantings, decreased in later plantings, and was inversely related to protein content. The oil content was also inversely related to mean daily temperature during the grain-filling period. The northern tablelands was a more favourable region for rapeseed production than the northwestern slopes in terms of both grain yield and oil content. Implications of changes in the primary components of yield which are responsible for yield variations with planting date are discussed in relation to breeding objectives for rapeseed cultivar improvement.

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*Part 11, Aust. J. Agric. Res., 29: 711 (1978).
Problems in tree replacement. III.* The effects of cultural practices and soil fumigation on root-lesion nematodes and on the growth of apple replants
Authors: Colbran RC
Published: November 2004

The growth of replant apple trees cv. Delicious was much less in field plots after a mixture of cover crops, including rye cv. Black Winter and lupin cv. New Zealand Blue, had been grown for 16 months than where the land had been left to volunteer weeds or kept free of plant growth. In a subsequent glasshouse experiment, growing rye or blue lupin in old orchard soil before planting apple seedlings caused severe stunting. In a field trial, soil fumigation with dichloropropene-dichloropropane (DD) before planting increased the first season's shoot growth of apple trees cv. Delicious after rye cv. Black Winter by 79% and after lupin cv. New Zealand Blue by 60%. Trees grew well after prairie grass cv. Priebe or oats cv. Saia, increases due to fumigation being 4.0 and 4.5% respectively. In a glasshouse experiment rye and blue lupin were shown to be much better hosts for the root-lesion nematode Pratylenchus penetrans than prairie grass or oats. A survey of Queensland apple orchards indicated that Pratylenchus penetvans and another species previously identified as Pratylenchus coffeae often occurred together. In a glasshouse experiment the addition of large numbers of P. penetrans to soil severely stunted apple seedlings cv. Granny Smith, whereas the other Pratylenchus species had little effect.

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*Part II, J. Aust. Inst. Agric. Sci., 20: 234 (1954).
Compensatory growth in sheep
Authors: Thornton RF , Hood RL , Jones PN , Re VM
Published: November 2004

Some attributes of the body composition of Dorset Horn x Merino wethers, which were either continuously grown or subjected to one or two periods of starvation-weight loss, realimentation and compensatory growth, were studied. Periods of restricted feed intake were imposed when liveweights were either below (23 kg) or above (43 kg) the level generally regarded as a mature liveweight (c. 31 kg) for such sheep. Loss of liveweight resulted in different responses in the meat of immature and mature animals. The meat from immature sheep was depleted of fat, whereas that from mature sheep increased in fat content. Loss of fat from the meat of immature sheep was associated with both atrophy and hypoplasia of the subcutaneous adipose cells, but in mature sheep there was atrophy without hypoplasia of these adipose cells. Although the greatest loss of fat was from the meat, proportionately more fat was lost from the offal, particularly in mature sheep. The amount of protein in the carcass meat was similar in control, starved, or realimented sheep of the same body weight. During the first few days of realimentation the sheep consumed three to four times as much food per day as during the starvation periods; the apparent digestibility of the food was increased from 53–68% to 80–90%; liveweight gain was 500–600 g/day, and there were increases in fat, water and protein in the meat of realimented animals. Sheep which had been starved and realimented, either once or twice, rapidly achieved liveweights equal to those of continuously grown animals and were similar to them in both body and meat composition.
Cereal chlorotic mottle virus — a rhabdovirus of Gramineae in Australia transmitted by Nesoclutha pallida (Evans)
Authors: Greber RS
Published: November 2004

An undescribed rhabdovirus was found in eight species of Gramineae at locations extending over 1000 km of the tropical and subtropical Australian east coast. The incidence in maize was usually low but sometimes reached 50% in susceptible hybrids. Cereal chlorotic mottle virus (CCMV) was shown experimentally to infect Avena sativa L., Digitaria ciliaris (Retz.) Koeler, Dinebra retroflexa (Fahl.) Panz., Echinochloa colona (L.) Link., Eleusine coracana (L.) Gaertn., Eleusine indica (L.) Gaertn., Hordeum vulgare L., Triticum aestivum L. and Zea mays L. Symptoms in all hosts began as chlorotic striations, but were often reduced to a fine chlorotic mottle in subsequent growth. After a 3-day acquisition, 50% of individuals of the cicadellid Nesoclutha pallida (Evans) transmitted CCMV in consecutive test feeds with only occasional failures, but some insects then failed to transmit for up to 30 days before death. The time between acquisition and first transmission was 11–24 days and the time for symptom development in the plant was 11–21 days. The virus was acquired and transmitted by both nymphs and adults and by males and females. Transmission continued through the moult to adult. In negative stain the particles were bullet-shaped, 214 by 75 nm, with a net-like surface pattern and core width of 28 nm. There were c. 48 helix cross-striations and 52 surface projections around the full perimeter of bacilliform particles when viewed after brief fixing with glutaraldehyde before staining.
Regrowth characteristics of lucerne under different systems of grazing management
Authors: Leach GJ
Published: November 2004

The regrowth characteristics of lucerne (Medicago sativa cv. Hunter River) were measured within an experiment conducted at Lawes, south-eastern Queensland, from 1971 to 1977 (Leach 1979). The experiment included six grazing and three mowing treatments: (1) R32/G4, (2) R32/G16, (3) R44/G4, (4) R44/G16, (5) R56/G4, (6) R40/G8, (7) R36/M, (8) R48/M and (9) R60/M, where R represents the days of rest between grazings (G) or mowings (M) and G the days of grazing after each rest period. These treatments formed cycle lengths of 36, 48 or 60 days, and regrowth experiments were usually undertaken when the ends of two or more defoliation cycles coincided. There were 15 regrowth experiments: experiments 1-9 were conducted over the first 720 days, experiments 10–14 over the next 720 days, and experiment 15 after another 720 days. In experiments 1-9 an initial harvest was made on day 0, and the regrowth was measured after 8 and 24 days. In experiments 10-14 there were harvests on days 0 and 24, and in experiment 15 on days 0 and 14. Amounts of regrowth were more strongly influenced by season and by soil moisture status than by imposed treatments, with final yields differing by up to 10-fold between winter and summer experiments. Seasonal differences in shoot size, and to a lesser extent in shoot numbers, were also much larger than treatment effects within experiments. These results appeared to be a consequence of the grazing and mowing systems being selected from within a recommended range for lucerne, and also of ensuring that moisture equivalent to the long-term average was received each month. Within experiments the yield of regrowth increased as the resting interval between defoliations increased, with a twofold difference between treatment extremes in some experiments. In general, grazing for 16 days led to better regrowth yields than grazing for 4 days which was in turn superior to mowing. Retaining residues after grazing generally increased regrowth, particularly following 16 days of grazing. However, residues greater than 80–100 g m-2 decreased regrowth. Most treatment differences were particularly evident on day 8, which indicated that treatments affected regrowth mainly through the speed of regrowth resumption after grazing or mowing. Although treatment effects on total regrowth yield were attributable to change in both shoot numbers and shoot size, the latter component was usually the more important determinant. Regrowth yield per unit area was maintained by compensating increases in yield per plant, whilst lucerne density fell from an initial 50 plants m-2 to about 30 plants m-2 over the first 3 years, but subsequent losses of lucerne plants led to decreased yields per unit area.
The use of non-carcass parts in the prediction of beef carcass composition on the slaughter floor
Authors: Johnson ER
Published: November 2004

Ninety-five steers were used to develop a method of estimating the weights or percentages of the four carcass tissues—muscle, bone, fat and connective tissue—while the carcasses were still on the slaughter floor. From an investigation of a number of non-carcass parts it was found that three measurements could be used to estimate all four carcass components. The measurements were (a) short-cut tongue weight; (b) foreshanks weight; (c) hot side weight. Simple and multiple regression equations were developed to estimate the weights of muscle, bone and connective tissue in the chilled side, and the accuracy of the estimates was compared with that of recorded prediction methods. The most useful equations employed short-cut tongue weight and hot side weight to estimate total side muscle weight, and foreshanks weight to estimate both total side bone weight and total side connective tissue weight. Fat weight was estimated from hot side weight and the estimates of the weights of the other three carcass components. This technique was more accurate than the Australian Beef Carcase Appraisal System and Butterfield's equation, both of which use fat thickness measurement at the 10th rib. When fat thickness measurement was included in regression equations, the estimates of muscle weight and fat weight were slightly improved. Advantages of using the 'non-carcass parts' technique are as follows. All four major carcass components are predicted; the carcass components can be recorded as absolute weights or percentages of chilled side weight; chilled side components are predicted whilst the hot side is still on the slaughter floor; no commercial loss occurs in carcass, offals or by-products; all measurements used in prediction are weights; and fat thickness measurements may be included in the prediction. The additional information enables producers to make a more critical assessment of the nutritive performance and genetic progress of their herds.
The basis for a procedure to specify soil physical properties of a seed bed for wheat
Authors: Collis-George N , Lloyd JE
Published: November 2004

The rationale of characterizing seed beds prepared for wheat by describing the environment at a distance from the plant/soil interface by a selected number of measurements on a bulk basis in the horizontal plane at small increments of depth is discussed. A field procedure is described of in situ measurements to specify the soil conditions of biological consequence to germination and emergence. Measurements at small increments of depth are made to determine: (i) moisture status by moisture content and by moisture potential; (ii) aeration status by air-filled porosity; (iii) temperature regime by monitoring the soil temperature profile with depth; (iv) soil strength by the bulk shear strength of the soil under in situ stress conditions. Field results suggest that the described field procedure is suitable for the routine study of soils involving a wide range of moisture contents, of moisture potentials and of structure. The results show that, within the top 15 cm of a prepared seed bed, soil physical properties change markedly with depth. In particular, tenfold increases of bulk shear strength were measured. Results also showed that bulk shear strength could not be predicted from penetrometer readings and that the mean aerial temperature at 1.2 m is not sufficient to define the mean temperature regime of the developing seedling. The field procedure described is recommended for the characterization of seed beds.
Studies on the behaviour of mushroom spores in relation to the epidemiology of virus disease
Authors: Nair NG
Published: November 2004

The Cholodny slide technique has been successfully used to study the behaviour of virus-infected spores in the casing on mushroom beds in relation to the epidemiology of virus disease. The results show that virus-infected spores can transmit the disease to mushroom mycelium in the casing through germination and anastomosis under a wide range of growing conditions such as levels of moisture, pH and salinity in the casing, type of casing material and cropping temperature. Peziza ostracoderma stimulated the germination of virus-infected mushroom spores, whereas Sporendonema purpurascens and Trichoderma sp. inhibited their germination. The significance of these fungal moulds on the epidemiology of mushroom virus disease is discussed.
Comparative performance of six Stylosanthes species in three acid soils
Authors: Carvalho MMde , Andrew CS , Edwards DG , Asher CJ , De Carvalho MM
Published: November 2004

The yield rcsponse of six Stylosanthes species to a factorial combination of four lime rates and two phosphorus levels applied to three acid soils (Coolum, Kogan, Rochedale) was determined in a pot experiment. The unlimed soils were of similar pH, but differed widely in exchangeable aluminium content. Aluminium toxicity appeared to be a major limitation to growth in the three soils. In the unlimed soils, the most severe yield restriction was observed in the Coolum soil, which had the highest soluble aluminium concentration (55 �M), and the least restriction in the Kogan soil, which had the lowest soluble aluminium concentration (37 �M). All six species achieved maximum yield in the three soils when the soluble aluminium concentration was reduced to values below 21 �M . The strong yield responses observed with little change in soluble aluminium at the higher lime rates in the Coolum and Rochedale soils may be due to either a further reduction in aluminium toxicity associated with increasing concentration of soluble polymeric species or the direct alleviation of hydrogen ion toxicity. The observed responses to lime do not appear to involve direct calcium effects, nor do they involve alleviation of manganese toxicity or molybdenum deficiency. Maximum yield was associated with reduction in aluminium saturation to less than 5% of the effective cation exchange capacity in all three soils. However, when examined across the three soils, aluminium saturation and also the exchangeable aluminium content were both unsatisfactory predictors of plant performance. The largest and smallest restrictions on growth were observed in soils with similar aluminium saturation (Coolum 14.4%, Kogan 17.6% respectively), while the Rochedale soil with its much higher aluminium saturation (42.0%) was intermediate in degree of growth restriction. Phosphorus and nitrogen deficiencies also limited plant growth, but the magnitude of their effects varied among soils and species.
The responses to defoliation of two strains of subterranean clover, differing in growth habit, when grown in swards
Authors: Rossiter RC , Collins WJ
Published: November 2004

Dense swards of two strains of T. subterraneum-herein referred to as C and P-were compared at two heights of cutting-1.5 cm (low) and 5.0 cm (high)-and two frequencies of defoliation- 1-weekly (frequent) and 4- or 5-weekly (infrequent). Strain C has smaller leaves than P and a compact, in contrast to a lax, growth habit. The swards (initial density of c. 25 plants/dm2) were grown in boxes, out of doors, at Perth from 27 April to 20 September. Mean daily solar radiation varied from c. 10 to 16 MJ/m2 and average daily maximum and minimum temperatures were c. 20� and 10�C respectively. The principal finding was that under defoliation stress (i.e. low cutting) strain C yielded more than P, whereas at a lower level of stress (high cutting) there was usually little if any difference between these strains. This effect was established for the most part before the first harvest, at day 55; thereafter, with continued defoliation stress, strain P appeared to worsen slightly relative to C. The results provide support for the view that strains with a compact growth habit are less susceptible to defoliation (or grazing) stress than taller strains of lax growth habit. Generally, the total yield of tops and also the effective yield (as cut and removed material) decreased when cutting height was lowered. Also, infrequent cutting increased effective yield, particularly under low density (four plants/dm2) as observed in an ancillary experiment.
The digestion of nitrogen associated with plant cell wall in the stomach and small intestine of the sheep
Authors: Hogan JP , Lindsay JR
Published: November 2004

The digestion of dietary cell wall constituents was estimated during measurements of the passage of digesta from the stomach and intestines of sheep. Two groups of four sheep were used, and they were fed on either mature wheaten hay at 600 g/d or immature dried ryegrass at 800 g/d. Cell wall constituents comprised c. 58.7% and 39.8% of the organic matter in the two diets, while the nitrogen associated with cell wall was equivalent respectively to 14.1 and 24.6 % of dietary nitrogen. With wheaten hay, 45 % of cell wall organic matter and 25 % of cell wall nitrogen were digested in the stomach. The corresponding values for ryegrass were, respectively, 81 and 89 %. The nitrogen in cell wall contributed about 9% of non-ammonia nitrogen in digesta leaving the stomach and 15 % in digesta leaving the ileum with wheaten hay, but only 4-5 % at each site with ryegrass. Although the release of amino acids from cell wall in the small intestine was less than from the remaining crude protein in digesta, it was concluded that the amounts involved were too small to have much effect on the apparent release of amino acids in digesta passing through the small intestine.
Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: genetic analyses of pre-weaning performance of first-cross calves
Authors: Barlow R , O'Neill GH
Published: November 2004

First-cross calves of Simmental (S), Friesian (F), and Brahman (B) sires were compared with straight-bred calves of Hereford (H) sires over 5 years at Grafton, N.S.W. There was a total of 775 calves sired by 205 bulls with complete records of performance from conception to weaning. Analyses were conducted to determine sire breed and sire breed x environment effects, and to provide paternal half-sib estimates of heritabilities and genetic and phenotypic correlations. Various models were used to ascertain the sensitivity of genetic parameters to the removal of different sources of variation. Among females, S x H were heaviest at birth, while among males, B x H were heaviest. The regression coefficient of birth weight on gestation length was significantly greater for B x H calves than for other crosses. All crosses grew significantly faster to weaning and were significantly heavier at weaning than H x H calves. However, there were a number of significant interactions between sire breed and environmental variables for measures of pre-weaning growth. S x H and F x H calves appeared most sensitive to environmental variation, while B x H appeared least sensitive. The significance of this is discussed. Estimates of heritability for most traits were high. Values derived by using simple models were: gestation length, 0.68; birth weight, 0.56; average daily gain (ADG) to weaning, 0.47; weaning weight, 0.54; eyelid pigmentation, 0.50. Heritabilities of birth weight and ADG during the early pre-weaning period appeared most sensitive to the amount of environmental variation removed in the model. Gestation length was positively correlated with size at birth but negatively correlated with growth to weaning. There were large positive genetic correlations among various measures of size at birth, and among various measures of growth to weaning. When compared with ADG to weaning, weaning weight was more strongly correlated with birth weight, but less strongly correlated with gestation length. The results also indicated that selection for gain over a fixed time period, immediately prior to weaning, would be as efficient as direct selection for total ADG to weaning.
Relative efficiency of individual selection and reference sire progeny test schemes for beef production
Authors: Morris CA , Jones LP , Hopkins IR
Published: November 2004

Individual selection on the basis of adjusted yearling weight records (policy 1) was compared with selection of proven sires based on progeny test results ('progeny test selection'). The major assumptions in the comparisons were that herd sizes were 100 recorded cows, and that each herd used four joining groups. It was assumed that 25 herds cooperated in using two reference sires in artificial breeding to link progeny test data from young bulls in natural service, thereby increasing selection intensity without the loss in accuracy normally suffered in a single multi-sired herd. In the progeny test comparisons, preselection of young bulls for progeny testing (policy 2) was also compared with random selection among young bulls for progeny testing (policy 3). This paper contains a limited number of comparisons only, in order to indicate the possible extent of selection pressure with different policies. Comparisons in terms of annual genetic progress ranked the policies in the order 2 (greatest), 1, 3, with policy 2 being better than 3 by 90-110%. The advantage of policy 2 over policy 1 was 26-38%. In all cases, using bulls first as yearlings was preferable to 2 1/4 years in terms of annual genetic gain. With individual selection, keeping bulls for 1 year compared with 2 or 3 years had little effect on annual gain, as the rise in selection intensity balanced the rise in generation interval. Inbreeding change per year was more affected, lower rates resulting from bulls being used for 1 year only. Inbreeding rates were small with progeny test selection as described here, as long as proven sons came from young bulls as well as proven sires. The effect of selection intensity under progeny test selection with preselection becomes diluted to 25% in its contribution to annual genetic change. Thus some degree of assortative mating may be useful, or wider use of proven sires relative to young sires. With preselection the break-even number of cooperating progeny test herds was low (three herds), compared with equal rates of genetic gain from individual selection.
Studies on pigs prepared with re-entrant cannulas. 2. Disappearance of dry matter, nitrogen and amino acids from diets containing different protein sources
Authors: Alimon AR , Farrell DJ
Published: November 2004

Quantitative estimates of disappearances of dry matter, nitrogen and amino acids anterior to the mid-point and terminal ileumof the small intestine were made in pigs prepared with re-entrant cannulas and offered six diets containing wheat alone or supplemented with either meat meal, fish meal, peanut meal, soybean meal or sunflower meal. Apparent digestibilities of dietary dry matter and nitrogen were also estimated by faecal measurements. Disappearance of dry matter and nitrogen was greater anterior to the mid-point than at the end of the small intestine and the rectum. Amounts disappearing at each location and between the three locations differed significantly between protein sources. Up to 10% of dietary dry matter and nitrogen disappeared in the large intestine. For lysine, methionine, threonine and valine, absorption was greater anterior than posterior to the midpoint of the small intestine for all diets except that containing only wheat. Measurements made of the disappearance of amino acids anterior to the large intestine indicated that the apparent availability of the majority of ammo acids of peanut meal, followed by soybean meal, was greater than those of meat meal (52 % crude protein) and fish meal (50 % crude protein).
The effects of heat stress on the development of the foetal lamb
Authors: Hopkins PS , Nolan CJ , Pepper PM
Published: November 2004

Environmental heat stress in tropical sheep suppressed lamb birth weight, but the animals which did not experience hyperthermia under natural environmental conditions gave birth to significantly heavicr (P<0.01) lambs than their less adapted counterparts. Climate chamber studies designed to simulate the rectal temperature patterns of tropical sheep demonstrated that, without nutritional intervention, heat stress during the last month of pregnancy significantly retarded foetal growth (birth weight 2.3 kg v. 3.4 kg; P< 0.01) and maturation of wool follicles (P< 0.01). By comparison, severe nutritional restrictions during the last 3 months of pregnancy also caused a significant reduction in lamb birth weight (3.2 kg v. 3.9 kg; P<O.01), but this difference was not so marked.
Selenium supplementation of grazing sheep. I. Effects of selenium drenching and other factors on plasma and erythrocyte glutathione peroxidase activities and blood selenium concentrations of lambs and ewes
Authors: Peter DW , Board PG , Palmer MJ
Published: November 2004

Lambs or ewes grazing pastures in the low selenium region of New England in New South Wales were used to study the effects of selenium supplementation on blood and plasma levels of selenium and glutathione peroxidase (GSH-px), and to assess the possibility of using GSH-px activity as an indicator of selenium availability or selenium status in grazing sheep. When lambs were drenched with selenium at 14 days of age there were large and rapid increases in the initially low levels of plasma and erythrocyte GSH-px. The increase in plasma GSH-px was transitory, and a second selenium drench administered to half the treated lambs at 42 days did not evoke any further increase. Erythrocyte GSH-px activities of treated lambs remained elevated for a longer period than plasma GSH-px, and the second selenium drench extended the period of elevation. Alterations in plasma GSH-px of adult ewes drenched with selenium were similar to those observed in the lambs, but erythrocyte GSH-px activities increased much more slowly. The changes in plasma and erythrocyte GSH-px were accompanied by significant alterations in plasma and whole blood concentrations of selenium. Increases in whole blood selenium, because of the plasma component, were much more rapid than those in erythrocyte GSH-px. Transfer of ewes to a new grazing area with a different soil and pasture type led to similar changes in plasma and erythrocyte GSH-px to those produced by selenium drenching. Small increases with time were also observed in the erythrocyte GSH-px activity of untreated ewes grazing the same pasture continuously. These changes were presumably the result of changes in the selenium content and/or availability in the pasture. It was concluded that regular estimations of erythrocyte or whole blood GSH-px activities could be used as an indication of selenium availability and the selenium status of grazing sheep. Changes in pasture and/or grazing area, and the fact that erythrocyte GSH-px activity of adult animals does not immediately attain a new equilibrium value when selenium intake alters must however be taken into account.
Depressed fodder quality and increased oestrogenic activity of lucerne infected with Pseudopeziza medicaginis
Authors: Morgan WC , Parbery DG
Published: November 2004

As well as reducing dry matter production of lucerne, infection of 15 % of the leaf area by Pseucbpeziza medicaginis reduced digestibility by 14% and crude protein content by 16%. Infection caused oestrogenic activity in green lucerne.
Studies on the interactions between Fusarium oxysporum f.sp. lycopersici, Verticillium dahliae and Meloidogyne spp. in resistant and susceptible tomatoes
Authors: Price TV , McLeod RW , Sumeghy JB
Published: November 2004

The interactions between Verticillium dahliae, Fusarium oxysporum f. sp. lycopersici Race 1, Meloidogyne javanica, M. incognita and M. hapla on four hybrid tomato cultivars H1, H2, H3, and H4, bred for resistance to all pathogcns, and the susceptible cultivar 'Rouge de Marmande' after 56 days were investigated. The resistance of the hybrids was confirmed with no appreciable difference between the hybrids. Galling in the hybrids was due to M. hapla, the hybrids being less resistant to this species. Galling was significantly (P = 0.05) decreased in the presence of F. oxysporum f. sp. lycopersici. Meloidogyne spp. did not increase infection by V. dahliae or F. oxysporum f. sp. lycopersici. Infection by F. oxysporum f. sp. lycopersici was significantly (P = 0.05) increased in the presence of V. dalzliae plus Meloidogyne spp. Infection by V. clahliae was low throughout the experiment. V. dahliae was isolated more frequently in the presence of F. oxysporum f. sp. lycopersici. The decrease in galling in the presence of F. oxysporum f. sp. lycopersici was countered by the presence of V. dahliae. In the susceptible cultlvar and after 77 days, the presence of V. dahliae decreased the frequency of isolation of F. oxysporum f. sp. lycopersici, but there was no effect of F. oxysporum f. sp. lycopersici on isolation frequency of V. dahliue.
A comparison of methods of inducing a pause in egg production in crossbred layers
Authors: Daniel M , Balnave D
Published: November 2004

Three methods of inducing a pause in egg production in 84-week-old crossbred layers were compared with the conventional method (i) of feed and water restriction. The alternative methods were the feeding of: (ii) a nutritionally balanced diet high in zinc, (iii) a nutritionally balanced diet low in calcium, and (iv) a nutritionally imbalanced diet low in calcium in the form of wheat alone. Birds on the low-calcium diet and birds fed only on wheat were slow to reduce their rates of lay, and their subsequent rates of egg production were significantly lower than those of birds from the other treatments. Leg weakness was a major problem in birds on the nutritionally balanced, low-calcium diet but not in birds fed on wheat only. In a second experiment, graded levels of supplementary zinc were used to determine the optimum concentration required to induce a pause in egg production. Compared with birds rested by the conventional method, the birds given a diet high in zinc (18.7 g/kg diet) took approximately the same time to cease laying and to return to 50% production, and there were no significant differences in any of the production parameters examined. When graded levels of dietary zinc were used, only the two highest levels (7.5 and 18.7 g/kg) were effective in producing a pause in egg production. Feed intake was related to dietary zinc levels: high dietary zinc supplementation suppressed appetite and reduced daily feed intake to extremely low levels.
A synoptic approach for crop loss assessment used to study wheat. IV. The description of cultural practices and the combination of cultural data with soil data
Authors: Stynes BA , Veitch LG
Published: November 2004

From an initial set of 13 measurements taken to define previous land use and the cultural practices adopted by farmers on Yorke Peninsula, S.A., an alternative set of eight variables was derived. The reduced number of variables retained almost all of the information present in the original set and were close to being statistically independent. This simplification is desirable for the later study, when these variables will be considered for inclusion in regression models to predict the growth and yield of wheat. A weak association between these variables and the soil variables specified in Paer III indicated that farmers were not strongly influenced by soil type and properties when deciding which cultural practices to adopt.
Effects of watering technique and pot size on response of soybean cultivars to applied zinc
Authors: Hunter MN , Byth DE , Edwards DG , Asher CJ
Published: November 2004

Effects of two watering techniques and three pot sizes on the growth of two soybean cultivars in a soil (vertisol) of low zinc status were studied in the glasshouse. Plants responded more to applied zinc when supplied with a constant water table (cwT) than when irrigated by the more common watering-to-weight method. The cwT technique accentuated zinc response through stimulation of growth in plants supplied with zinc, not because of intensified zinc deficiency. Nodule production was also greater in cwT-treated plants than in plants regularly watered to weight. Experimental precision was not significantly different in three experiments, despite differences between them in soil quantity per pot (1500, 750 and 375 g) and plants per pot (three, two or one). The advantages of the c w ~ system, and its use with a single plant growing in 375 g of soil as the test unit, are discussed in relation to screening soybeans for reaction to zinc deficiency.
Effects of level of larval intake on the productivity and physiological and metabolic responses of lambs infected with Ostertagia circumcincta
Authors: Symons LEA , Steel JW , Jones WO
Published: November 2004

The interrelationships between level of exposure to Ostevtagia circumcincta infection, production loss and physiological and metabolic effects were examined over 24 weeks in groups of weaner lambs on larval dosing regimes (LDR) of either 0, 1200, 3750, 12000, 37500 or 120000 infective larvae per week. During the first 12 weeks, liveweight gain and wool growth were significantly depressed in lambs on both LDR 37 500 and 120000, but food consumption was significantly reduced only on the latter. Faecal nitrogen excretion was increased by both of these LDR but the efficiency of retention of apparently digested nitrogen was generally unchanged. Enteric plasma loss and albumin turnover rate were significantly increased by LL)R 120000 during the 4th week, at which time albumin concentration was most severely depressed. After the 12th week there were generally no significant effects of infection, and total liveweight gain over 24 weeks was similar for all lambs. Recovery coincided with a decline in faecal egg counts, abomasal worm counts and plasma pepsinogen concentrations. It was concluded that, under the conditions of this experiment, an intake of more than 12000 O. civcumcinctu larvae per week is necessary to have significant effects on the physiological and metabolic functions of weaner lambs with consequent losses in productivity.
The interaction of nutrients and tillage methods on wheat and weed development
Authors: Gates CT , Jones DB , Muller WJ , Hicks JS
Published: November 2004

This study evaluated the relative performance of spring wheat under direct drill in comparison with more conventional tillage methods, under a wide range of nutrition treatments and in the presence of an aggressive weed component, Phalaris aguatica (syn. tuberosa). Four tillages were applied: conventional fallow; direct drilled plus pre-emergence grazing; direct drilled plus the pre-sowing herbicide glyphosate; and reduced tillage. There were five levels of phosphorus and two of nitrogen, and a post-emergent herbicide 2,4-D was applied to half of the plots. Growth of crop and weeds was measured at six stages of development, together with final yields. Nitrogen and phosphorus uptake and concentration were measured throughout development. Plant nutrients were not released as efficiently with direct drilling as cultivation. Crop plants in direct drilled were not only deficient in nitrogen but also in phosphorus during early development, whereas cultivation ensured that high nutrient levels were attained in fallow plots. Direct drilled plots did not appear to recover completely from this initial deficiency unless fertilized and freed from weed competition. When weeds were controlled, yields of direct drilled plots were comparable with yields of fallow at higher levels of phosphorus and nitrogen, because at these high nutrient levels yields in fallow were suppressed. However, weed competition and/or poorer nutrition lowered direct drill yields. It was concluded that direct drilling requires a new approach, sensitive to the changed agronomic conditions that it engenders. Competition with weeds may be avoided by choosing a vigorous cultivar, avoiding dominant weed species and using herbicides strategically and economically. A high plane of nutrition proniotes the success of direct drilling.
Copper nutrition of subterranean clover (Trifolium subterraneum L. cv. Seaton Park). I. Effects of copper supply on growth and development
Authors: Reuter DJ , Robson AD , Loneragan JF , Tranthim-Fryer DJ
Published: November 2004

Effects of severe and moderate copper deficiency on the development of leaves and lateral branches, on the distribution of dry weight within the plant, and on seed yield of Seaton Park subterranean clover were assessed as part of three glasshouse experiments. Copper deficiency markedly depressed top and root growth without producing any distinctive symptoms. It retarded phasic development by delaying development of leaves and lateral branches, senescence of plant parts, and flowering: it also depressed the proportion of stem plus petiole in plant tops and decreased internode elongation, pollen fertility and the number of burrs and seeds formed. As a result of its effect in delaying flowering, copper deficiency would depress seed production particularly strongly when low soil water supply shortens the growing season. The need for suitable procedures for diagnosing copper deficiency is emphasized by the lack of specific plant symptoms in this species.
The ecology of the free-living stages of Ostertagia ostertagi in a winter rainfall region
Authors: Young RR , Anderson N
Published: November 2004

On a series of pasture plots, 500 g pats of cattle faeces containing eggs of the trichostrongylid Ostevtagia ostertagi were deposited at intervals of about 6 weeks from June 1976 to June 1977. The development and survival of eggs and larvae in dung pats and the survival of larvae on surrounding herbage and soil were measured and expressed as a percentage of the initial population of eggs. During summer months comparisons were made between the pats on irrigated and those on non-irrigated plots. Minimum temperatures within dung pats were always greater than those required for development, and infective larvae were recovered from all plots. The onset of development was delayed from 3 to 12 days in summer and from 34 to 68 days in winter, which led to a wide distribution of developmental stages. Rates of development were closely related to the temperatures in soil and dung pats, and mortality rates of pre-infective stages increased very rapidly with increasing temperatures and decreasing moisture levels. Infective larvae were present in abundance on herbage and in soil between 6 and 10 weeks after deposition, provided that the moisture content of these was high. Mortality of these larvae was low during winter and early spring but increased rapidly in mid- to late spring, irrespective of the time of deposition of dung pats. Mortality rates of infective larvae in dung pats deposited in either spring or summer were low and a large proportion of these larvae were capable of moving into herbage and soil after autumn rains. Irrigation during summer did not provide ideal conditions for the development of infective larvae from eggs, but hastened larval migration from dung pats.
Yield improvement in high lysine barley
Authors: Oram RN , Doll H
Published: November 2004

Twenty-three barley genotypes were grown in field plots and the seed-yield components and seed composition were investigated. Ten malting and feed cultivars and waxy endosperm selection lines had the standard concentration of lysine in their seed protein. The other genotypes were five different natural or induced high-lysine mutants and/or selection lines developed from them. High-lysine lines were lower yielding than the most productive normal lysine cultivars because of a decrease in weight per seed, accompanied by a reduced content of the carbohydrates extractable with dimethyl sulfoxide. Ris� mutant no. 7 was exceptional in having fewer seeds per unit area and a normal carbohydrate content. Within the group of lys 3 homozygotes derived from Ris� no. 1508, the higher yielding lines had more seeds per unit area, higher concentrations of extractable carbohydrates, and lower concentrations of crude protein. Similar trends with yield also occurred among the lines homozygous for the lys gene from Hiproly. The yields of the most productive lys and lys 3 homozygotes approached that of Clipper, the leading Australian malting cultivar, but were 25% lower than that of the most productive feed barley, Cutter. The other mutants, Ris� no. 7, Ris� no. 29 and Clipper 500, were lower yielding than the better lys and lys 3 selections. The possibilities for improving the yield and energy content of the latter two high-lysine types by selection are discussed.
Copper status of sheep grazing pastures fertilized with sulfur and molybdenum
Authors: Langlands JP , Bowles JE , Donald GE , Smith AJ , Paull DR
Published: November 2004

Varying quantities of sodium molybdate, superphosphate and copper sulfate were applied to 30 plots, and changes in hepatic copper concentration in sheep grazing these plots were measured by using a biopsy technique. A relationship between changes in hepatic copper storage and the copper and sulfur x molybdenum concentrations in the green forage on offer was calculated. This relationship was used to calculate the quantity of copper in green forage on offer necessary to maintain hepatic copper concentration constant when the forage varied in sulfur and molybdenum concentration. In a second experiment sodium molybdate was applied to pasture grazed by sheep at rates varying from 0 to 2000 g molybdenum per ha. Black sheep grazing pasture dressed with 2000 g molybdenum per ha, grew white wool for four months following molybdenum application; this corresponded to the period when molybdenum concentration in herbage on offer was greatest. There were also changes in blood, wool, kidney and liver composition following molybdenum application but these were small when molybdenum was applied at the usual commercial rate. The results of both experiments suggest that the application of molybdenum to pasture at commercial rates is unlikely to induce copper deficiencies in grazing sheep.
Distribution and variability in development of the genus Trigonella in Asia Minor and its possible use in Australian environments
Authors: Halloran GM , Pennell AL
Published: November 2004

A number of Trigonella species were examined for their possible use in Australian environments. There was a wide variability in flowering time in Trigonella. Under an outdoor autumn sowing the range in flowering time was comparable with that found within early- to late-flowering Australian commercial cultivars of subterranean clover. The upper level of vernalization response was much lower in Trigonella than in subterranean clover. Good prospects exist within Trigonella for selecting genotypes with close adaptation (in terms of appropriate developmental patterns) to a range of Australian environments, a range at least as wide as that now occupied by subterranean clover and annual medic.