bluuebunny/crossref_metadata_2025 huggingface dataset:
Milk replacers for preruminant lambs: limiting amino acids in two soybean protein isolates determined with a change-over design
Authors: Pelaez R , Walker DM
Published: November 2004

Preruminant male crossbred lambs, aged about 2 weeks at the start of the experiment, were used. Low protein milk replacers (0.10 of total energy as protein) containing isolated soybean protein (ISP-A or ISP-B) as the sole source of protein were supplemented with mixtures of amino acids. Experiment 1a. Six lambs were each given six isonitrogenous diets in a 6 x 6 change-over design with 4-day dietary periods. The diets contained ISP-B and were supplemented with (1) methionine alone, or methionine plus (2) lysine, (3) isoleucine, (4) threonine, (5) valine or (6) tryptophan. Experiment 1b. Groups of six lambs were given diets containing either ISP-A or ISP-B. Each lamb within a group was given six diets in a 6 x 6 change-over design with 4-day dietary periods. One diet was supplemented with six amino acids (Met, Lys, Isol, Thr, Val and Try) whilst the other five diets had one amino acid (not Met) omitted. Nitrogen balances were determined in experiments 1a and 1b on the last 2 days of each dietary period. Experiment 2. Two groups of four lambs were used in a conventional 12-day nitrogen balance experiment. One group was given the milk replacer containing ISP-B supplemented with the six amino acids used in experiment lb, and the other group the same basal diet supplemented only with Met, Lys and Thr. The addition of single amino acids in addition to methionine did not improve nitrogen balances. Lambs given diets supplemented with Met plus Thr, Val or Try had significantly lower nitrogen balances than those given a supplement of Met alone (experiment 1a). Lambs given diets in which Lys or Thr were omitted from the mixture of six amino acids had Lower nitrogen baIances than any other lambs (experiment 1b). It was concluded that Lys and Thr were equally second limiting in ISP-A and ISP-B at the 0.10 protein energy concentration. The retention of apparently digested nitrogen by lambs given ISP-B supplemented with Met, Lys and Thr (0.669) was significantly higher than that of lambs given ISP-B supplemented with six amino acids (0.590; experiment 2). The mean digestibility coefficient of nitrogen in ISP-B (0.842 ± 0.009) was significantly higher than that in ISP-A (0.764 ± 0.014) and the diets containing ISP-B were more readily accepted by the lambs.
The cellularity of ovine adipose tissue
Authors: Hood RL , Thornton RF
Published: November 2004

The cellular growth of adipose tissue from Dorset Horn x Merino wethers was characterized by both hypertrophy and hyperplasia of adipose cells until the sheep were c. 11 months old, after which hypertrophy of existing adipose cells was solely responsible for increases in adipose tissue mass. Omental adipose tissue contained larger adipose cells than either the perirenal or subcutaneous sites. The weight of fat which had been deposited in the boneless carcass meat and the internal adipose tissue depots were linearly and positively correlated with the volume of the adipose cells. Decreases in the mass of adipose tissue, which accompanied nutritional restriction, were due to decreased adipose cell size, since no change was observed in the number of adipose cells per carcass after loss in weight. The cellularity characteristics of rehabilitated sheep were similar to those of sheep which had undergone continuous growth.
Host resistance to cattle tick (Boophilus microplus) in Brahman (Bos indicus) cattle. IV.* Ages of ticks rejected
Authors: Wagland BM
Published: November 2004

The stages of development of Boophilus microplus against which Brahman (Bos indicus) cattle manifest resistance were investigated by analysing the age distributions of ticks in populations on five steers showing different levels of resistance. The populations of ticks were established by infesting the steers each day with 1000 larvae, until each animal yielded a relatively stable number of engorged female ticks daily. The ticks were recovered by killing the steers and processing their hides in hot caustic soda. Ticks were allocated to age categories on the basis of their lengths. Analyses of the age distributions showed that between 36 and 80% of larvae were rejected in the first 24 h, and losses were greater from hosts with high levels of resistance. Some newly moulted nymphs failed to establish and were lost, and the growth of newly moulted females was retarded but most engorged successfully. The results also indicated that significant numbers of larvae and nymphs were lost either during the final stage of engorgement or after they had engorged. These findings are compared with losses of the tick from European (B. taurus) cattle.

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* Part III, Aust. J. Agric. Res., 29: 401 (1978).
Soil and plant resistances to water absorption by plant root systems
Authors: Burch GJ
Published: November 2004

A study of water absorption by root systems of two herbage species, white clover (Trifolium repens L.) and tall fescue (Festuca arundinacea Schreb.), was used to partition the resistances to water flux between the soil and plant. A large and almost constant plant resistance influenced the pattern of water absorption until the soil resistance reached about 1.5 x 103 MPa s cm-3. This corresponded to an extraction of almost 80% of the available soil water. Water absorption from progressively deeper soil layers showed no evidence of any substantial resistance to water flux through the root xylem. Therefore, in wet soils, water movement into and through a root system is predominantly influenced by a large resistance to the radial water flux through root tissues outside the xylem. The radial resistance values for unit (cm) length of root were 6.49 x 106 and 6.54 x 106 MPa s cm-2 for clover and fescue respectively. A model of water uptake has been described which introduces two modified parameters for integrating the soil water potential (ψ) and the soil-root conductance (κ), over an entire root system. This study, along with other evidence from the literature, would indicate that for unit length of root the radial resistance to water absorption is reasonably similar, not only for an entire root system but also for a number of different species. An underestimation of the radial soil resistance (Rsr) to water absorption suggests that a root contact resistance (Rc) exists which could be due to the shrinkage of the soil or root, or both, with drying of the soil. This effect caused an increase in resistance to water absorption of about 48 x Rsr for fescue and 71 x Rsr for clover. This difference in Rc between the two species was attributed to a contrast in root morphology, especially a difference in the average root diameters of the two species.
Nitrogen metabolism in Brahman cross, buffalo, banteng and Shorthorn steers fed on low-quality roughage
Authors: Norton BW , Moran JB , Nolan JV
Published: November 2004

Urea metabolism was studied in Brahman cross, buffalo, banteng and Shorthorn cattle offered a low quality hay. Intravenous injections of [14C]urea and 51Cr-EDTA were used to determine the irreversible loss of urea from the plasma, the degradation of urea in the rumen and lower digestive tract, and the glomerular filtration rate. When species were compared at equal liveweights and nitrogen intakes, buffaloes had significantly higher (P < 0.05) plasma urea concentrations and rates of irreversible loss of urea carbon from plasma than the other species. There were no significant differences between species in urinary urea excretion. Urea degradation in the digestive tract was linearly related to the irreversible loss of urea, and the proportion of irreversible urea loss degraded was significantly (P < 0.05) lower in Shorthorn cattle (48%) than in the other species (73–91%). Shorthorn cattle reabsorbed urea from the glomerular filtrate with a lower efficiency (60%) than did the other species (85–94%). In Brahman cross, buffalo and banteng, plasma urea recycled to the rumen was a relatively constant amount (4.3 g nitrogen/d) and represented on average 39% of the urea degraded in all parts of the digestive tract. Urea degraded in the digestive tract increased linearly with increasing irreversible loss of urea from plasma. It was concluded that, despite significant differences between species in urea synthesis and degradation, there was little indication that these differences constituted a significant nitrogen conservation mechanism in any one species.
Studies of weaned lambs before, during and after a period of weight loss. I. Energy and nitrogen utilization
Authors: McCGraham N , Searle TW
Published: November 2004

Lambs were given a balanced diet immediately after weaning at 6 weeks and grown from 15 to 25 kg on a high level of feeding. They were then underfed for 21 weeks, which caused weight to return to 17 kg, and finally allowed to regain weight on ad libitum feeding. Brief periods of 'maintenance' feeding were interposed in each phase. Nitrogen and energy balances were obtained for successive weeks by measuring food intake and all losses. There was general agreement between these results summed for each phase of the experiment and data obtained from a parallel slaughter trial. Metabolizable energy was a constant 56% of gross energy or 11.3 MJ/kg dry matter. Estimated energy requirement for maintenance was depressed by 28% after a few weeks of undernutrition, but efficiency of utilizing additional energy was also lowered, cancelling the potential benefit for compensation. There was no difference in efficiency between normal and compensatory growth. Protein contributed 25–40% (varying inversely with body weight) of energy balance during both normal growth and regain but only 10% during prolonged weight loss. There was some evidence of improved nitrogen economy in the first month of compensation.
Effects of soil water content and foliar fertilization with nitrogen and phosphorus in late season on the yield and composition of wheat
Authors: Alston AM
Published: November 2004

Wheat was grown in reconstructed profiles of a sandy red-brown earth in pots 120 cm deep. Ammonium sulfate (90 mg nitrogen per pot) and/or monocalcium phosphate (75 mg phosphorus per pot) were added to the topsoil. In one experiment, water treatments were introduced when the wheat reached ear emergence to provide (a) dry topsoil and water shortage; (b) dry topsoil but ample water supply in the subsoil; or (c) ample water supply, with both topsoil and subsoil wet. Additional nitrogen (82–164 mg per pot as urea) and/or phosphorus (9–18 mg per pot as phosphoric acid) were added to the plants in foliar sprays after ear emergence. In a second experiment in which water treatment (b) was applied, the dry surface soil was wetted at different stages of plant growth, viz. ear emergence, anthesis or the dough stage. In both experiments the yield and concentration of nitrogen and phosphorus in the wheat were measured at maturity. Total dry matter production was little affected by the water content of the soil after ear emergence, but grain yield was increased relative to that of straw where the topsoil was wet at the dough stage. Application of nitrogen at the time of sowing generally increased the yield of grain and straw, but phosphorus had little effect on yield. Additional foliar application of nitrogen after ear emergence increased grain yield where water stress was low: foliar application of phosphorus increased grain yield only when applied with nitrogen. Nitrogen concentration in the grain was little affected by adding nitrogen to the soil but was increased by late foliar application of nitrogen. Phosphorus concentrations were increased by phosphorus and decreased by nitrogen applications.
Effect of competition by white clover on the seed production characteristics of subterranean clover
Authors: Smith RCG , Crespo MC
Published: November 2004

During the third year following establishment, the production, hard-seededness and dormancy of subterranean clover cv. Woogenellup when grown along and in association with white clover was studied in commercial pastures on the Northern Tablelands of New South Wales. The pasture containing only subterranean clover produced 757 mg seed dm-2, whereas in competition with white clover only 34 mg dm-2 was produced. A study was made of seed production by subterranean clover grown in competition with white clover. As the level of competition increased there was a marked decline in individual plant size, flowers per plant, seeds per burr and total seed production per plant, whereas no significant effects on seed dormancy and hard-seededness were apparent. A study of the seed and seedling population of the pure subterranean clover paddock revealed a recovery of 13% of the initial seed population as surviving plants and 32% as viable hard seeds at the beginning of winter. These observations suggest that competition from white clover could be a significant factor in some situations influencing the persistence of subterranean clover on the Northern Tablelands, and selection of cultivars with better ecological combining ability with white clover might be a worth-while objective.
Effects of vacuum and pressure infiltration of calcium chloride and storage temperature on the incidence of bitter pit and low temperature breakdown of apples
Authors: Scott KJ , Wills RBH
Published: November 2004

Post-harvest treatment of apples with calcium chloride markedly reduced bitter pit and breakdown in several cultivars during three seasons in Australia and New Zealand. Infiltration of calcium chloride at pressures above or below atmospheric pressure improved the control over that obtained by simple immersion of the fruit in the calcium chloride solution, and was effective in the absence of the usual field sprays of calcium nitrate. These new treatments retained much of their effectiveness when the fruit were afterwards rinsed with water to reduce the risk of injury to the fruit or the grading equipment. The treatments were effective whether the fruit had open or closed calyces, but there were problems of excessive uptake and internal damage with some fruit having an open calyx. Commercial development of the process for closed calyx varieties such as Cox's Orange Pippin or Granny Smith is in progress. For the 3–4 month period required for export, the use of a lower temperature (0° instead of 3°C) improved the control of bitter pit, and a post-harvest calcium treatment reduced the incidence of low temperature breakdown.
The control of oestrus, ovulation and fertility in relation to artificial insemination in the Angora goat
Authors: Moore NW , Eppleston J
Published: November 2004

A total of 792 purebred and crossbred Angora does was used in an artificial insemination (AI) program. Does were treated with intravaginal pessaries containing 20 mg 'Cronolone' or with a single intramuscular injection of 100 µg of the prostaglandin analogue 'Estrumate' (I.C.I.) to control the time of oestrus, or they remained untreated. Pessaries were left in situ for 16, 18 or 20 days, while Estrumate was given 6–11, 13–16, or 18–20 days after oestrus or at unknown times after oestrus. After treatment the does were run with harnessed vasectomized bucks, and they were inspected for oestrus at 12-h intervals. Does in oestrus were inseminated 0–2 or 12–14 h after the detection of oestrus, and each doe received 0.1 ml semen collected by electroejaculation from Angora bucks. Treatments and results were: (1) pessaries—232 does treated and retained pessaries, 167 (72%) inseminated of which 82 (49%) kidded; (2) Estrumate at known times—115 does treated, 83 (72%) inseminated of which 36 (43%) kidded; (3) Estrumate at unknown times—151 does treated, 72 (48%) inseminated of which 40 (56%) kidded; (4) untreated—277 does, 223 (81%) inseminated of which 149 (67%) kidded. Time of AI after the detection of oestrus had little effect on kidding performance. In does treated with Estrumate at known times the majority (82%) were in oestrus 48–72 h after treatment with no effect of time of treatment on incidence of oestrus, or on fertility. Oestrus after removal of pessaries occurred 12–24 h earlier than after Estrumate, and there were effects of duration of insertion of pessaries on the time, and precision in time of oestrus. Oestrus occurred earlier and with less precision as the duration increased, and there was a suggestion of lowered fertility in does treated for 20 days, which indicated that the dose of Cronolone used in the pessaries was marginal. Overall, treatment depressed fertility, but the kidding performance of does treated with pessaries for 16 days and in oestrus 36-60 h after removal of pessaries approached that of untreated does (61 v. 67%).
Evolution of subterranean clover in South Australia. I. The strains and their distribution
Authors: Cocks PS , Phillips JR
Published: November 2004

The distributions of the strains of subterranean clover were determined from the presence of burrs in wool collected at the Adelaide Wool Sales. Of 7600 samples examined, nearly 1300 contained viable seeds. This seed was grown, the strains were identified, and their distributions in South Australia were mapped. Subterranean clover was found in wool from most areas with more than 400 mm of rain. However, it was absent from the climatically favourable Yorke Peninsula, and it seems clear that distribution of subterranean clover in South Australia is limited by the presence of alkaline soils. Divergent strains are widespread in South Australia. In all, 435 divergent strains were discovered from 325 farms. The presence of these strains leads us to believe that genetic change in subterranean clover, previously thought to be genetically stable, has been brought about by infrequent outcrossings, mainly in mixtures of cultivars. We discuss evidence for this proposal, and the consequences that it has for seed certification schemes. The distribution of flowering time amongst the divergent strains differed from the cultivars. Many of them flowered about half way between the mid-season cultivar Mount Barker and the early-flowering cultivar Dwalganup. There was no strain later than Tallarook, the latest-flowering cultivar, and very few earlier than Dwalganup. Flowering time of the divergent strains was weakly related to the length of growing season of the farms which produced the wool. Strains were also discovered which were morphologically identical with a cultivar but which flowered either earlier or later. The first-released cultivars, Mount Barker and Dwalganup, were the most widely distributed of all strains. Indeed success, in terms of the number of seeds of a cultivar found in the wool, could be broadly related to the number of years since release. The data illustrate the significance of the early-flowering cultivars on the distribution of subterranean clover, but indicate that, apart from T. brachycalycinum, there is little need in South Australia for yet earlier cultivars.
The effects of vegetation development upon achene production in the woody weed, groundsel bush (Baccharis halimifolia L.)
Authors: Panetta FD
Published: November 2004

An examination of the achene production of groundsel bush (Baccharis halimifolia L.) populations growing within two exotic softwood stands of differing ages revealed that substantial reductions in this variable occurred following canopy closure. Mean reproductive efficiency, estimated as the number of achenes per gram dry weight of understorey bushes within the older stand, was only 31% of the corresponding value for bushes growing within a stand prior to the occurrence of canopy closure. Only small differences were found in both cumulative germination percentage and germination rate of achenes collected from each population. Female bushes, when shaded to a level of 14% open sky radiation, demonstrated a 30% reduction in the number of flowers initiated per head and a 25% reduction in percentage achene fill. Floral initiation was found to be independent of the production of oil reserves. Whilst dramatic reductions in the achene production of understorey individuals occur with plantation development, it is suggested that the density of unmanipulated populations of B. halimifolia may prevent the invasion and development of dominance by native tree species.
Canning peach decline in Western Australia. I. Association between trunk cankers, trunk pruning wounds and crotch angles of scaffold limbs
Authors: Doepel RF , McLean GD , Goss OM
Published: November 2004

Decline of South African canning peach varieties, particularly commercial plantings of Keimoes, has occurred in Western Australia. From orchard observations and laboratory investigations, it is suggested that tree death follows on canker formation on the trunk. The cankers extend from areas of compressed dead bark between scaffold limbs and from large uncallused pruning wounds in the crotch and on the trunk. Wood-rotting fungi are considered to gain entry through the dead bark and uncallused wounds. Analysis of the data shows a highly significant relationship between many cankers and narrow crotch angles. No correlation has been established between the extent and severity of trunk pitting and the development of cankers.
The influence of radiant heat load on reproduction in the Merino ewe. I. The effect of timing and duration of heating
Authors: Sawyer GJ
Published: November 2004

Merino ewes were subjected to a source of radiant heat during early pregnancy in two experiments in which the incidence of embryonic death was examined as reflected by the proportion of ewes that failed to return to service but did not lamb. Ewes were artificially inseminated (day 0) and exposed to hot-room conditions during days 1–3, 4–6 or 7–9 or not at all (control) (experiment I), and during days 1–3, 1–6 or 1–9 or not at all (control) (experiment 2). Conditions in the hot room and control room were respectively 40–43°C and 1.36–3.06 kPa vapour pressure, and 22–26°C and 1.12–1.96 kPa. Ewes exposed to hot-room conditions had significantly higher rectal temperatures and respiration rates during treatment than did control ewes (40.2° v. 39.3° and 186 v. 61 respirations/min, P < 0.001). The number of ewes which conceived and eventually lambed was reduced by exposure to high environmental temperatures shortly after insemination. The most critical period was during the first 3 days after insemination. If ewes were heated for periods longer than this, fertility was not reduced significantly further. This suggested that the timing of the heating was more critical than the duration of heating in early pregnancy. The reduction in the number of ewes lambing (experiment 1) or in the number of ewes pregnant at 30 days (experiment 2) was due almost entirely to either fertilization failure or early embryo death. Most infertile ewes showed oestrus within a normal cycle (16–19 days). Only in experiment 1, where heating lasted 3 days, did ewes return to oestrus after extended intervals from insemination. In experiment 2 the proportion of ewes which showed oestrus after an extended period from insemination was very small. It was concluded that death of developed embryos due to the effects of high environmental temperatures during early pregnancy was insufficient to explain the large reproductive wastage associated with ewes which apparently conceive but fail to lamb.
Carcass characteristics of heavyweight crossbred lambs. I. Growth and carcass measurements
Authors: Atkins KD , Thompson JM
Published: November 2004

An experiment was conducted at Temora Agricultural Research Station to assess the potential for producing heavyweight lamb carcasses from breeds currently used in the prime lamb industry. Growth to slaughter, dressing percentage and carcass measurements of lambs from six breed crosses were compared over a range of carcass weights. The lambs were the progeny of Dorset Horn and Border Leicester rams joined to Merino, Corriedale and Border Leicester x Merino first-cross ewes. Within each breed combination, lambs were allocated to be slaughtered at 34, 44 or 54 kg liveweight. Lambs sired by Dorset Horn rams were slightly larger at birth and weaning, and reached their slaughter weights at a younger age, than lambs sired by Border Leicester rams. Lambs from Border Leicester x Merino ewes grew 10% faster than lambs from Corriedale ewes. The progeny of Merino ewes were always slowest-growing, and this was more marked at higher weights. Carcasses from the slower-growing genotypes tended to be larger in skeletal size and had a lower dressing percentage than carcasses from faster-growing genotypes, when adjusted to the same carcass weight. Fat depth at the 12th-13th rib increased, on average, by 20% for each 10% increase in carcass weight, over the range of carcass weights examined. The rate of increase in carcass fatness was significantly lower in lambs sired by Dorset Horn rams and lambs from Merino ewes, compared with lambs of the other breeds.
Prediction of the influence of water, sowing date and planting density on dry matter production of wheat
Authors: Hanks RJ , Puckridge DW
Published: November 2004

A water balance model was used to calculate dry matter yields for wheat. The prediction used initial soil water, irrigation, rainfall and pan evaporation as inputs. Leaf area index (LAI) was estimated by an empirical equation and changes in LAI were determined by the ratio of predicted to potential transpiration and relative density. Time of sowing influenced time of maximum LAI. Dry matter production was calculated from equations relating LAI and photosynthesis. The model was tested with data from wheat crops in South Australia which had been grown with large differences in water supply, planting density and sowing date between seasons. There was good agreement between predicted and measured production.
The relationship between pre-anthesis development and seed yield of spring rape (Brassica napus L.)
Authors: Thurling N , Das LDV
Published: November 2004

Experiments were carried out to determine the influence of flowering time and the pattern of pre-anthesis development on the seed yield of spring rape. The responses of six cultivars to variation in sowing date at a site 100 km east of Perth indicated that the duration of the vegetative phase and the time of the season at which seed development commenced were both important determinants of seed yield. Seed yields decreased with a reduction in the duration of vegetative development and an extension in the time between 1 October and first flowering. These data suggested that an optimal flowering time for this and similar environments would, assuming a mid-June sowing, be one that allowed for at least 100 days of pre-anthesis development and ensured that seed development commenced no later than 1 October. In a controlled environment experiment, different patterns of pre-anthesis development induced in the cultivar Target by exposure to different photoperiodic regimes were associated with substantial variation in seed yield. This variation in seed yield was primarily associated with differences in the duration of the stem elongation phase: an increase in duration resulted in the production of greater numbers of flowers (and pods) per plant and ultimately greater numbers of seeds per plant. As seed size was largely unaffected by variation in photoperiod during pre-anthesis development, extension of the stem elongation phase was accompanied by significant increases in seed yield. Substantial genotypic variation in the duration of the stem elongation phase was observed among a group of spring rape cultivars and their F1 hybrids grown in a controlled environment comparable with that prevailing in the field during this phase of development. Longer periods of stem elongation were accompanied by increased pod production and higher seed yields. Evidence from this and earlier studies indicated that there was sufficient genetic variation in pre-anthesis development to facilitate yield improvement through selection based on developmental characters. The utilization of controlled environment facilities in conducting such a selection program is discussed.
Development of the grape berry. I. Effects of time of flowering and competition
Authors: Coombe BG
Published: November 2004

In an experiment on field-grown Vitis vinifera cv. Muscat Gordo Blanco, six times of flowering were established by using early and late developers amongst primary and secondary bunches on winter- and spring-pruned vines. Repeated measurements of the diameters of marked berries and of refraction (�Brix) of the juice of sampled berries were used to calculate berry volume and weight of solutes per berry. In a second experiment the effect of competition between bunches was tested by thinning. The volume-time curves were similar until 25 days after flowering, after which they diverged markedly. The chief reasons for divergence were the different rates and timing of deceleration during the first growth cycle, and the different lengths of the slow growth phase: berries from late flowers decelerated quickly but had a prolonged lag phase. Some, though not all, of these effects could be attributed to competition between bunches on the same vine. The inceptions of the solute accumulation phase and of the second growth cycle were coincident within treatments. The rates of increase in �Brix were uniform between treatments, despite large differences in berry volume increase. Solutes per berry increased linearly for 40 or more days, but at diverse rates that were influenced chiefly by the rate of volume increase in the second growth cycle. In some cases, solutes per berry continued to increase after berries had stopped growing. Temperature summations over the interval from flowering to 17�Brix were not constant.
Comparison of Stylosanthes humilis with S. hamata and S. subsericea in the Queensland dry tropics: effects on pasture composition and cattle liveweight gain
Authors: Gillard P , Edye LA , Hall RL
Published: November 2004

Two new accessions of perennial legumes, Stylosanthes hamata cv. Verano and S. subsericea, were compared under grazing with the annual S. humilis (Townsville stylo) at four sites in the dry tropics. One of the new accessions, S. subsericea, was largely eliminated from the comparison because of its susceptibility to anthracnose. Although Townsville stylo was well adapted at two of the sites where average rainfall exceeded 850 mm annually (Lansdown and Wrotham Park), the yield of Verano was significantly more after the establishment year. At these sites the original grasses were replaced by the annuals Diqitaria ciliaris and Brachiaria miliiformis. Where soil fertility was high (Lansdown), these grasses competed vigorously with the legumes; where soil fertility was low (Wrotham Park), the sward remained legume-dominant. The yield of Townsville stylo was low at the two sites where annual rainfall was less than 750 mm annually (Kangaroo Hills and Westwood). Verano produced very high yields at the warmer site (Kangaroo Hills) and became dominant in the third year; in subsequent years there was an increase in the improved grass Urochloa mosambicensis, which responded to the increase in soil fertility. At the cooler site (Westwood) the yield of Verano was poor. Cattle liveweight gains were similar on both the Townsville stylo and Verano pastures at Lansdown, and better on the Verano pasture only in one year at Wrotham Park. At Kangaroo Hills and Westwood, liveweight gains were significantly greater on the Verano pastures. The data suggested that differences in liveweight gain did not occur when the legume yield on both pastures exceeded 600 kg ha-1. This threshold was usually achieved at Lansdown and Wrotham Park, but rarely with Townsville stylo at Kangaroo Hills. Townsville stylo has until recently been the only legume suited to pasture improvement in the dry tropics. The results from this experiment show that the perennial legume Verano can now extend the range of legume-based pasture improvement in the dry tropics of northern Australia.
Infection of Kennebec potato with Verticillium albo-atrum
Authors: Sampson PJ
Published: November 2004

Infection of Kennebec potato plants by Verticillium albo-atrum (dark mycelium form) occurred when they were grown in soil samples collected after 4 years under perennial ryegrass-white clover pasture following an affected potato crop. Tuber transmission averaged 8 %, 13 % in the stolon half and 4% in the apical half. Infection readily spread from diseased to healthy plants that were growing in the same container of a peat-sand soil mix. Infection was detected in stems from the stage of early flowering; infection of a proportion of tubers had occurred by the stage of rapid tuber expansion. In some plants, tuber infection occurred in the absence of detectable stem infection. Latent infection was common and systemic movement was incomplete. The fungus was cultured from the above-ground stem more frequently than from other plant parts. In a field study, an infected potato crop produced soil-borne inoculum (which included infected dead haulms) that resulted in infection of 75 % of previously healthy plants of a subsequent crop. Current season spread was not detected in infector or bait crops by a runs test based on sequences of healthy and diseased plants. The use of pathogen-free stock and the removal of diseased plants from seed potato crops are unlikely to control the disease where V. albo-atrum is endemic.
Relationship of soil moisture to survival of Escherichia coli and Salmonella typhimurium in soils
Authors: Chandler DS , Craven JA
Published: November 2004

In a moist podzol type grey loam topsoil maintained under controlled conditions, persistence of inoculated Escherichia coli and Salmonella typhimurium cells was found to be similar with a death rate of about 14 days per log cycle. The death rate was not greatly affected by altering the growth conditions prior to inoculation of the soil. E. coli and S. typhimurium persistence was generally decreased in soil containing 85 % dry matter, with a rapid decline in cell numbers in soil containing more than 90% dry matter. E. coli survival was shown to be progressively reduced in soil: water mixtures containing less than 60% dry matter. Two of five different soil types tested were found to provide less favourable environments for inoculated cells, although soils of the same type collected on different occasions were not found to give consistent die-out rates. E. coli and S. typhzmurzum cells subjected to 14 days in dry soil were shown to have ability for regrowth when the soil was moistened.
The digestion of protein from forage diets in the small intestine of the sheep
Authors: Lindsay JR , Hogan JP , Donnelly JB
Published: November 2004

The digestion of nitrogen other than ammonia (NAN) in the small intestine of sheep fed on forage diets has been estimated by developing a structural relationship y = a+bx, where y = NAN (g/d) leaving the ilium and x = NAN leaving the abomasum. In this relationship the intercept a represents endogenous NAN passing from the ileum and the slope b the indigestibility of abomasal NAN; hence ( 1-b ) gives true digestibility. The values obtained (mean &SE) were: a = 1.04�0.32 and b = 0.34 � 0.02 , which indicated that the true digestibility of NAN leaving the abomasum was 66%. The amino acid composition of endogenous NAN leaving the ileum was estimated in ileal fluid collected from sheep whose rumens had been emptied and which were maintained by infusion of volatile fatty acids, minerals, vitamins and small amounts of amino acids into the stomach. The values obtained did not differ substantially from mean values obtained for abomasal and ileal digesta from sheep fed on four forage diets. Total amino acids (g/16 g NAN) in abomasal and ileal digesta and endogenous ileal fluid were 74.4, 62.9 and 82.5 respectively. From information on the true digestibility of abomasal NAN and the amino acid composition of digesta, estimates were made of the true absorption coefficients of individual amino acids from the small intestine. Values were mostly greater than 70% of the amount leaving the abomasum but for cystine the value was only 52%.
Critical phosphorus concentrations in parts of Macroptilium atropurpureum cv. Siratro and Desmodium intortum cv. Greenleaf as affected by plant age
Authors: Johansen C , Merkley KE , Dolby GR
Published: November 2004

Critical phosphorus concentrations were determined for different parts of Macroptilium atropurpureum cv. Siratro and Desmodium intortum cv. Greenleaf at several plant ages in order to establish an appropriate sampling technique for chemical analysis of phosphorus status. Critical phosphorus concentrations were derived by using a non-rectangular hyperbola functional relationship which allowed calculation of variance associated with critical values. When expressed relative to tissue dry weight, critical phosphorus concentrations in whole shoots declined from 0.30�0,03% (95% confidence limits) at 41 days from sowing to 0.09� 0.01 % at 77 days for Siratro and from 0.33 � 0.14 % at 45 days to 0.16 � 0.03 % at 73 days for Greenleaf. Similar declines in critical phosphorus concentration with plant age were measured for combinations of all parts of the upper shoot back to the fourth expanded leaf. Thus plant age effects and variability associated with each determination of critical phosphorus concentration would limit the practicability of phosphorus analysis in detecting marginal phosphorus deficiency. This especially applies to plants growing as perennials in pastures where identification of plant age is not possible. Plant age effects can be lessened to some extent when critical phosphorus concentrations are calculated relative to tissue water, but it is suggested that less empirical techniques of plant analysis are required if plant age effects on critical phosphorus concentrations are to be overcome.
Jojoba flower buds: temperature and photoperiod effects in breaking dormancy
Authors: Dunstone RL
Published: November 2004

Jojoba (Simmondsia chinensis [Link] Schneid.) is a long-lived desert shrub, valued for the liquid wax which makes up 50% of the seed weight. As attempts are being made to domesticate the species, it is important to understand the environmental factors controlling the reproductive cycle and governing seed yield. The effects of temperature and photoperiod in breaking flower bud dormancy were studied on plants growing under well-watered conditions in controlled environments. Plants 42-48 months old produced only dormant flower buds when growing in 27/22� to 36/31�C day/night temperature. When the plants were moved to lower temperatures of 24/19� or 18/13�, every plant produced a flowering flush. In two experiments, clonal material was grown at either 30/25� or 36/3l�C, then moved to lower temperature treatments. Down to the lowest temperature used (18/13�), the greater the drop in temperature, the greater the number of flowers which opened. Flowering occurred under both short (8 h) or long (16 h) photoperiods. There was a critical temperature in the region of 27/22� to 30/25�, above which no flowering occurred. Flowering was not dependent on a large diurnal temperature range, but occurred only if the plants were subjected to a low temperature for at least 21 days.
Factors affecting the growth of Pennisetum purpureum in the wet tropics. I. Short-term growth and regrowth
Authors: Ferraris R , Sinclair DF
Published: November 2004

Six plantings of elephant grass (Pennisetum purpureurn) were made at 2-monthly intervals in the wet tropics of north Queensland. Each crop was sampled for yield at monthly intervals. After 6 months' growth each crop was ratooned for a further 6 months' growth, with yield samples again being taken at monthly intervals. As well, stem elongation growth was measured twice weekly, together with various climatic parameters and soil moisture to 90 cm. Regrowths after each monthly harvest were sampled 1 month after cutting. Short-term growth, measured as elongation growth and averaged for the whole experimental period, was found to have a significant parabolic relationship with crop age and available soil moisture percentage, but not with average temperature or evaporation. Regrowth yields were found to be linearly and positively correlated with tiller density prior to ratooning and regrowth tiller density, with average regrowth temperature or regrowth degree days but linearly and negatively correlated with moisture regime, whether expressed as average parent-crop soil moisture prior to harvest, average regrowth soil moisture percentage or the summation of stress-free days. It was concluded that environmental limitations to growth in this environment, though relatively short lived, were significant in reducing long-term yields. Growth, however, was possible at all times.
Resistance of durum wheat cultivars to black point caused by Alternaria alternata
Authors: Southwell RJ , Wong PTW , Brown JF
Published: November 2004

Resistance of durum wheat cultivars to black point caused by Alternaria alternata was evaluated in the field in northern New South Wales. The cultivars tested showed a range of infection levels. The most susceptible cultivars were Duramba and Gaza, while those showing the greatest resistance were Wandell, Wascana and aus 15350.
Effect of protected casein supplements on pasture intake, milk yield and composition of cows in early lactation
Authors: Rogers GL , Porter RHD , Clarke T , Stewart JA
Published: November 2004

Thirty dairy cows in early lactation were individually fed in stalls on high quality pasture (Lolium peuenne, Dactylis glomerata and Trifoliium repens) and given either formaldehyde-treated casein or untreated casein at 1000 g/day. Nitrogen content and apparent digestibility of herbage nitrogen was 2.8 and 70.4% respectively. Treated casein significantly increased the yield of milk by 13 % and milk protein by 15 % although neither supplement affected milk composition. High-producing cows showed a greater response to formaldehyde-treated casein, with increases in milk yield of 0.5 �0.14 kg per kg increase in level of milk production. Increases in milk synthesis were associated with increased efficiency in utilization of nutrients and not with changes in pasture intake. The results support the hypothesis that formaldehyde-treated casein provided more protein for duodenal digestion and thereby increased the supply of essential amino acids which were limiting milk production. It is concluded that milk synthesis in cows fed solely on high quality pasture in early lactation is limited by the amount of protein absorbed post-ruminally.
Corrigendum - 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.
Variation in nitrogen, sulfur, selenium, cobalt, manganese, copper and zinc contents of grain from wheat and two lupin species grown in a range of Mediterranean environments
Authors: White CL , Robson AD , Fisher HM
Published: November 2004

Grains of Lupinus angustifolius, Lupinus albus and Triticum aestivum were sampled from 23 sites selected on the basis of three major rainfall categories (annual average greater than 450 mm; 325- 450 mm; less than 325 mm), and four soil types (infertile sands, sandy loams, sand over clay, and alkaline). The variation in concentrations of most nutrients were as great within rainfall or soil categories as between these categories, although selenium concentrations tended to be lower in grain from the highest rainfall zone. Lupin seed contained higher concentrations of nitrogen, sulfur, selenium, copper and zinc than wheat. The concentration of manganese varied between species and sites, with L. albus containing levels of up to 2000 �g/g at several sites. There was a positive correlation between manganese and cobalt concentrations in grain of L. angustifolius and L. albus at sites where manganese concentrations were above 50 and 500 �g/g respectively. The grain of L. angustifolius contained significantly lower concentrations of nitrogen, manganese, cobalt and copper than did L. albus, although there were considerable site differences. Nitrogen/sulfur ratios were wider in lupins (24/l for L. albus and 20.5/l for L. angustifolius) than in wheat grain (15.4/l). The ratios showed up to twofold range over all sites, which suggests that limitations in sulfur supply occurred at sites with a wide ratio. The concentrations of selenium, copper, zinc and cobalt were below the recommended dietary allowance for livestock at many sites, while the manganese concentrations in white lupin at several sites were at potentially toxic levels for animals. The nitrogen/sulfur ratio of grain was also outside the optimum for protein utilization by livestock. These findings highlight the need for some form of trace element and protein monitoring to avoid potential deficiency and toxicity problems in livestock consuming the grain.
The effect of hedging time on regrowth and flowering of mature Valencia orange trees
Authors: Bacon PE
Published: November 2004

Thirty-eight-year-old Valencia orange trees on Rough Lemon rootstock were hedged at monthly intervals from September 1973 to April 1974. Trees were hedged on the east and west sides. Size of cut stem, number and length of each flush, and fruit number were recorded for each flush. Regrowth rate was highest on trees hedged in mid-summer, but by the winter of 1976 first flush length was similar on all treatments, and there were no significant differences in the total length per shoot or in the number of first or second flush shoots. The number of third and fourth flush shoots were reduced on autumn hedged trees. Stem circumference, rather than hedging time, was the major determinant of regrowth vigour. Approximately 50% of stems cut before December had flowering regrowth next spring. In the following year all hedging treatments produced flowering regrowth. It was concluded that mature Valencia citrus should be hedged after harvest and between spring and mid-summer. Autumn hedging should be avoided because it results in reduced fruiting.