bluuebunny/crossref_metadata_2025 huggingface dataset:
A simulation model of kenaf for assisting fibre industry planning in northern Australia. IV. Analysis of climatic risk
Authors: Carberry PS , Carberry PS , Muchow RC , Muchow RC , McCown RL , McCown RL
Published: November 2004

The establishment of a pulp and paper industry based on kenaf (Hibiscus cannabinus L.) in semi-arid northern Australia requires clear demonstration of the long-term production potential of kenaf in this region. Owing to the high rainfall variability both within and among seasons, it would be difficult to assess the potential of a new dryland industry from traditional experimentation. Accordingly, this study was undertaken to assess the climatic risks to dryland kenaf production in the Northern Territory (NT) using the kenaf simulation model NTKENAF, which has been developed and validated for this climatic zone. The kenaf model was run, using long-term historical weather data, to determine optimal sowing strategies and expected yields at four representative sites in the NT. In the NT, a codict existed between sowing early, with resulting long duration and high yield potential, but high probability of plant mortality, and sowing later, with more reliable plant population, but shorter duration and lower yields. A general recommendation over all sites was for a sowing window extending from the start of November to mid-December each year; lower yields were simulated for earlier sowing dates due to problems with crop establishment, and for later sowing dates due to crop growth extending past the end of the wet season in most years. However, in circumstances of high rainfall prior to November, there was a yield advantage at several sites from sowing early. Over the 100 years of climatic data for Katherine (14� 28'S.) and sowing when 30 mm rainfall occurred in a 5-day period after 1 November, simulated stem yields for kenaf ranged from 800 to 17200 kg ha-1, with a mean stem yield of 8673 kg ha-1 and coefficient of variation of 42%. At the higher rainfall site of Douglas Daly (13� 48'S.), over 21 seasons and using the same sowing criterion, stem yields ranged from 4490 to 19 200 kg ha-1, with a mean stem yield of 12 509 kg ha-1 and coefficient of variation of 27%. Simulated stem yields were higher at the wettest site of Adelaide River (13� 06'S.) and lowest at the driest site of Larrimah (15� 36'S.). In the planning of a potential kenaf industry in the northern Australia, this research study has provided the essential information of yield probability distributions for kenaf crops grown at selected sites in the NT.
Development of a glasshouse assay for screening for partial resistance to P. vignae in cowpea
Authors: Davis RI , Irwin JAG , Imrie BC
Published: November 2004

A glasshouse-based root inoculation method for screening for partial resistance to P. vignae was developed. By infecting potting mix with 0.01 g dry weight mycelium kg-1 dry weight of mix, inoculum levels comparable to those found under natural conditions of infestation in the field were obtained. This screening assay was used to compare resistance levels of eight cowpea lines with those obtained following hypocotyl inoculation with races 1-4 of P. vignae. One of the lines tested, CPI 84853, expressed partial resistance to all four races in the root inoculation assay, although it was highly susceptible to race 4 following hypocotyl inoculation. This line, along with the root assay described in this paper, form a basis for the development of new cowpea cultivars with more durable resistance to P. vignae.
Soil management for irrigated vegetable production. II. Possible causes for slow vegetative growth of lettuce associated with zero tillage
Authors: Stirzaker RJ , Passioura JB , Sutton BG , Collis-George N
Published: November 2004

This work explores the consequences of using zero-tillage for irrigated vegetable production. The research is based on the hypothesis that, under the well-watered and adequately fertilized conditions prevailing in commercial vegetable growing, the reduced root density expected under zero-tillage should not limit vegetative growth. To test this hypothesis, irrigated lettuce crops were grown under a range of soil physical conditions on a hardsetting sandy loam soil. Crops were grown during the spring, autumn and summer, in order to compare zero-tillage and cultivation treatments under conditions of low, medium and high evaporative demand. Lettuce yields under zero-tillage were reduced relative to those under cultivation for each of these crops. However, calculations based on a model which describes the movement of water to roots show that the root length measured in the zero-tillage treatment greatly exceeded that required to meet the potential evaporative demand in the field. A possible explanation for the reduced growth is given, based on an inhibitory root signal which has been shown under controlled conditions to reduce shoot growth in hard soil even when the leaves are well supplied with water and nutrients. When lettuce was grown under zero-tillage, but following a crop of subterranean clover (Trifolium subterraneum L.) which senesced in summer to form an in-situ mulch, yield was as high as in cultivated soil. The soil near the surface in this treatment was not only moister and physically weaker than that from the conventional zero-tillage treatment, but also likely to contain biopores which would provide zones of low root impedance in an otherwise hard soil.
Nitrogen fixation by a subclover-grass mixture grown on two acid soils treated with lime
Authors: Butler JHA
Published: November 2004

The effect of liming on symbiotic N2 fixation by subclover (Trifolium subteraneum) grown with ryegrass (Lolium multiflorum) was measured under glasshouse conditions using the 15N dilution technique. Two acid soils, a sand and a loam, were treated with two rates of lime or left unamended. In general, lime addition to both soils increased total dry matter yields, but in the loam, grass made up most of the increase, whereas in the sand, subclover made up all of the increase in dry matter. N2 fixation in both untreated soils was negligible. Lime addition increased the percentage N in the total herbage, had little effect on the proportion (Patm) and amount of N fixed by subclover grown on the loam, but dramatically increased both Pat, and the amount of N fixed by subclover growing in the sand. Subclover grown in the loam was poorly nodulated, despite the addition of large amounts of nodulaid (rhizobium survival in the soil was not a factor), but was well nodulated in the sand, thus explaining the lack of fixation in the loam. Higher amounts of inorganic N produced in the loam shortly after germination have the potential to inhibit nodulation in this soil. Also the loam, after liming but before planting, contained higher amounts of nitrate-N and total inorganic N than the sand, and the total inorganic N mineralized by the loam (518 versus 347 mg per pot by harvest) would also have had some effect on N2 fixation had nodulation taken place at a later date. Levels of critical nutrients (B, Ca, Cu, K, Mg, Mo and P) were measured in the clover tops, but no element appeared to be in deficit or excess, except A1 which could not be excluded as being at a toxic level in the limed loam in the present trial.
Lamb birthweight in sheep differently acclimatized to a hot environment
Authors: McCrabb GJ , McDonald BJ , Hennoste LM
Published: November 2004

Two groups of ewes were selected from a flock of 151 ewes in the semi-arid tropics of northern Australia, according to their rectal temperature measured at 1600 hours on each of 3 consecutive days when maximum daily ambient temperature was 36� 0.5�C. Low temperature status (LRT) ewes had a rectal temperature of <39.8�C at 1600 hours on each of the 3 days, while high temperature status (HRT) ewes had a rectal temperature of >39.9�C. These ewes were mated 8 months later and exposed to a summer gestation under normal grazing conditions. Maximum and minimum daily ambient temperatures during pregnancy were 37�0.3�C and 21�0.3�C respectively. Rectal temperature measured at both 0800 and 1600 hours for HRT ewes was higher (P < 0.01) than for LRT ewes during pregnancy. LRT ewes produced lambs of higher (P < 0.05) birthweight and ponderal index than HRT ewes. The physiological basis for the difference in fetal growth in ewes which respond differently to a hot climate has not been identified, but possible mechanisms are discussed.
Manipulation of ley pastures with herbicides to control take-all
Authors: MacLeod WJ , MacNish GC , Thorn CW
Published: November 2004

The effect of grass-selective and broad-spectrum herbicides in pasture:wheat rotation experiments were studied from 1981 to 1986 at Esperance, W.A. The quantity of pasture and the proportion of grass present in the pasture phases were determined. Pastures were grazed by sheep. Incidence and severity of take-all and grain yield were measured in the wheat phases. The rotations studied were either a 2 year pasture: 1 year crop or 1 year pasture: 1 year crop. Herbicide treatments greatly decreased the grass content of pastures in the year of application, and this effect carried over to the second year in the 2 year pasture: 1 year crop rotation. Herbicide reduced total pasture yield in the year of application, but not in the year following. Herbicide treatment of pastures decreased the incidence and severity of take-all in the following wheat crop. Crop yields were increased following treated pastures and to a greater extent than could be exdained bv decreased take-all alone. Incidence of take-all depended primarily upon the quantity of grass in the previous pasture (5.4% incidence of take-all per 100 kg ha-1 grass dry matter in the previous pasture). Incidence of take-all was also related to the incidence of take-all in previous wheat crops and the quantity of grass in the pasture in the preceding two years.
Distribution of annual Trifolium species in Morocco
Authors: Beale PE , Bounejmate M , Lahlou A , Marx DB , Christiansen S
Published: November 2004

An ecogeographic survey was conducted in six key agricultural zones in Morocco to study the abundance and the relationship between the natural distribution of annual Trifolium species and environmental factors. Sixteen species of annual Trifolium species were identified. Most prolific was T. scabrum and the least were T. striatum and T. bocconei. Fifty-five percent of the sites had no Trifolium and the average number of species per site was 2.2. An average seed yield of 4.8 kg ha-1 was obtained. Both soil and climatic factors affected the occurrence of Trifolium species. Rainfall, pH and phosphorus content were the most determinant factors affecting the distribution of Trifolium species in Morocco.
Distribution of carbon and nitrogen in a long-term cropping system and permanent pasture system
Authors: Robertson FA , Myers RJK , Saffigna PG
Published: November 2004

Nitrogen (N) limitation to productivity of sown perennial grass pastures on the brigalow lands of S.E. Queensland contrasts with adequate N supply to annual crops grown on the same soil. In order to understand this anomaly, the distribution of N and carbon (C) under permanent green panic pasture and under continuous cropping with grain sorghum was compared in an 18 month field study. Total soil N and organic C (0-10 cm) were, respectively, 0.37 and 3.20% under green panic and 0.23 and 2.31% under sorghum. Soil microbial biomass (0-28 cm) contained 246 kg N and 1490 kg C ha-1 under green panic and 147 kg N and 744 kg C ha-1 under sorghum. Enhanced microbial growth under pasture was attributed to the continuous input of available C from surface litter and roots. The C/N ratio of pasture residues was high (greater than 50) and conducive to immobilization of N. Availability of N under pasture was further reduced by approximately 50% of plant N being immobilized in standing dead tissue. Under sorghum, the microbial biomass was well supplied with N, but was limited by C availability. The soil under sorghum received a single large C input when crop residues were returned after harvest. The differences in N availability, and hence productivity, of these soils under cropping and permanent pasture were due primarily to differences in the timing and quality of C inputs.
The root morphology of Lupinus angustifolius in relation to other Lupinus species
Authors: Clements JC , White PF , Buirchell BJ
Published: November 2004

Commercial L. angustifolius cultivation is restricted to acid to neutral coarse-textured soils in Australia. An unsuitable root system may be part of the reason for the poor performance on fine-textured or alkaline soils. As a first step to examine this question plants of 12 annual Lupinus species were grown in a coarse soil with the aim of describing the range of root morphologies within the genus and to compare these to commercial L. angustifolius. A wide range of rooting patterns were observed. The differences in the dominance of the taproot was pronounced between species. The commercial genotype of L. angustifolius occupied an extreme within the range of root morphologies of the species. Roots of L. angustifolius consisted of a dominant taproot and a relatively high number of primary lateral roots but few secondary roots. In contrast, the primary, secondary and tertiary lateral roots of L. pilosus, L. mutabilis, L. atlanticus, L. palaestinus and L. micranthus were more dominant than the taproot. The length and distribution of primary lateral roots along the taproot also varied between species. The number of primary lateral roots fell rapidly with depth in L. angustifolius and L. mutabilis, while the other species had a more even distribution. L. angustifolius had a less extensive root system and relatively thick roots when compared to species such as L. albus and L. mutabilis. L. luteus also had relatively thick roots. The relatively thick roots and less extensive lateral root system in commercial L. angustifolius may partially explain its poor growth on fine-textured soils, where a greater proliferation of finer, lateral roots may be necessary. Proteoid root formation was observed for L. albus, L. cosentinii, L. pilosus, L. palaestinus, L. micranthus, L. digitatus, L. princei and L. atlanticus. They were particularly numerous in L. micranthus and L. albus. The structure of proteoid root clusters varied between species.
Accumulation, distribution and redistribution of dry matter and mineral nutrients in fruits of canola (oilseed rape), and the effects of nitrogen fertilizer and windrowing
Authors: Hocking PJ , Mason L
Published: November 2004

Field studies were made at Ariah Park and Cowra to investigate the accumulation and distribution of dry matter and 12 mineral nutrients in fruits (pods) of canola (oilseed rape), and to assess the significance of redistribution of nutrients from the pod walls to the seeds. Flowers 4-6 from the base of the primary inflorescence were tagged at anthesis, and pods which developed from these were harvested at weekly intervals until maturity. Pods reached maturity 82 days after anthesis of the parent flowers. N fertilizer increased seed yields at both sites, but had negligible effects on the dry matter per pod, pod length, 1000 seed wt, seed number per pod, seed oil concentration, and concentrations of mineral nutrients in the pod walls and seeds. Similarly, there were no differences in these parameters due to locality, with the exceptions that seed oil per cent and concentrations of S and Mn in the pod walls and IVln in seeds were higher at Cowra than at Ariah Park. Pods had attained their maximum length and fresh and dry weights by the end of the first half of their development, but seeds had accumulated only 35% of their mature dry weight at this stage. Seeds gained dry matter after dehydration of the fruit began, but the pod walls did not. Seeds had 61% of the pod's dry matter, >70% of its P, N, Zn, Fe and Mg, 30-55% of its K, S, Mn, Cu and Ca, but <20% of its Na and C1. Dry matter was redistributed from the pod walls with 20% efficiency, and nutrients with from 17% (Cu) to 88% (P) efficiency; however, there was negligible redistribution of K, S, Ca, Na, C1, Fe and Mn from the pod walls. Redistributed dry matter and nutrients from the pod walls could have provided from 11% (dry matter) to 25% (N) of the amount in mature seeds. Concentrations of N, P, Mg, Mn, Zn and Cu in the pod walls declined as they developed, whereas those of Ca and Cl increased. Concentrations of nutrients in developing seeds remained fairly static. Windrowing plants when 40% of the seeds had changed to their mature colour did not affect seed oil per cent or concentrations of nutrients, but reduced seed size and seed yields by 10%. Data from the pod study also support the current recommendation to windrow when 40-60% of seeds reach their mature colour.
Effects of ractopamine in pig muscles: histology, calpains and β-adrenergic receptors
Authors: Sainz RD , Kim YS , Dunshea FR , Campbell RG
Published: November 2004

Ractopamine is a G-adrenergic agonist which stimulates growth in pigs, but this effect appears to decline during prolonged treatment. This study was conducted to examine possible mechanisms for the growth-enhancing activity of ractopamine, and its attenuation. Finishing gilts (47.0 kg body weight) were allocated to one of five experimental groups: CON, control diet for 6 weeks; RAC, ractopamine (20 mg/kg feed) for 6 weeks; C/R, CON for 3 weeks and RAC for 3 weeks; R/C, RAC for 3 weeks and CON for 3 weeks; and ALT, CON for weeks 1, 3 and 5, and RAC in weeks 2, 4 and 6. All pigs were fed 2.25 kg/day of a commercial grower ration (13 MJ DE/kg, 16% crude protein, 0.6 g available lysine/MJ DE). Samples of the m. longissirnus dorsi were taken at slaughter and analysed for fibre histology, calpain activities and G -adrenergic receptor populations. Ractopamine had no effect on muscle fibre proportions, but Type II fibres were smaller in pigs treated for the first 3 weeks only (R/C; 2477 8m2, P < 0.05), and tended to be larger in pigs treated for the second 3 weeks only (C/R; 3670 8m2, P < 0.10), as compared to controls (3086 8m2). Giant fibres were also larger in C/R pigs as compared to controls (9027 v. 6917 8m2, P < 0.05). Type I fibres were unaffected by any of the treatments. Calpain II and calpastatin activities were unaffected by any treatment, but calpain I activities were reduced in C/R pigs as compared to controls (0.331 v. 0.504 U/g, P < 0.05), indicating that reduced capacity for protein degradation might partially account for the hypertrophic effect of ractopamine. Pigs treated with ractopamine for 3 weeks before slaughter had reduced numbers of G-adrenoceptors in muscle than controls (2.34 v. 3.17 fmol/mg protein, P < 0.05), which may be responsible for the observed attenuation in growth enhancement over time.
Poor performance of broilers fed diets containing soyabean meal as the sole protein concentrate
Authors: Irish GG , Balnave D
Published: November 2004

Broiler chickens fed diets containing soyabean meal as the sole dietary protein concentrate consistently showed poor growth in a number of feeding trials. Soyabean meal processed in Australia gave inferior performance to soyabean meal processed in the U.S.A. Growth was improved at similar dietary energy and protein concentrations by replacing approximately 25% of the soyabean meal with either sunflower meal, cottonseed meal or rapeseed meal but not by supplementing the soyabean meal diet with lysine, methionine and cystine. The responses of broilers to the soyabean meal diet were unaffected by the cereal component of the diet and the beneficial responses observed when sunflower meal replaced part of the soyabean meal were not related to the amino acid composition or digestibility of the diets.
Estimates of covariance components for growth traits of Australian Charolais cattle
Authors: Meyer K
Published: November 2004

Restricted maximum likelihood estimates of covariance components and the resulting genetic parameters were obtained for birth, weaning, yearling and final weights and postweaning gain of Australian Charolais cattle fitting an animal model including genetic or permanent environmental maternal effects. No 'carry-over' of maternal effects till weaning on postweaning weights was found. Direct heritability estimates were 34, 41 and 22% for yearling weight, final weight and postweaning gain respectively. Maternal genetic effects were not important for birth weight and were small for weaning weight. Permanent environmental maternal effects affected birth weight to a moderate extent, but were the main factor determining weaning weight, explaining 4% and 21% of the respective phenotypic variance while direct heritabilities were 21% (birth) and 12% (weaning). Direct genetic correlations between birth and the other weights were medium, ranging from 0.44 to 0.67, while estimates between weaning, yearling and final weight were close to unity.
Characteristics of frost in a major wheat-growing region of Australia
Authors: Boer R , Campbell LC , Fletcher DJ
Published: November 2004

Frost at anthesis of wheat reduces grain set. Characteristics of frost in a large section of the wheat belt of one Australian state (N.S.W.) are described. Using cluster analysis, the region can be divided into four homogeneous areas according to five general characteristics of frost These characteristics are the mean Julian day of first and last frost, the mean number of frost days, the proportion of single-day frosts (days on which a frost did not occur on the following day) from August to October and the proportion of frost free periods from August to October of less than 5 days' duration. All these characteristics were found to,be closely related to altitude in all areas, but not to latitude or longitude. Within each area, regression equations were developed which explained at least 87% of the variation in four of the general characteristics. Thus, altitude appears to be a useful predictor for these characteristics. The validity of each equation was tested using three independent data sets. The mean percentage errors for the mean Julian day of first and last frost and the proportion of single-day frosts from August to October were 5, 5 and 8% respectively. Errors for the mean number of frost days and proportion of frost free periods from August to October of less than 5 days duration were approximately 7% for one site and approximately 20% for two other sites. The characteristics of frost in the period in which most winter crops flower are also described. The characteristics are the mean date of last heavy frost and last frost, and frost spells in each of August, September and October. In order to minimize risk from frost during anthesis and from high temperature and water stress during grain filling, this analysis suggests that anthesis should occur in early/mid September, late September/early October and early/mid October for the western, central and eastern parts of the region respectively. For areas in the north-eastern and south-eastern parts that are above 500 m, anthesis should occur mid/late October and early/mid November respectively. These analytical findings are consistent with field studies on wheat. A weak negative correlation between the first and the last frost is present in most of the sites of the region. This suggests that if in any particular year the first frost occurs earlier than its long-term mean, then the last frost tends to occur later than its long-term mean.
Potential precision of the δ15N natural abundance method in field estimates of nitrogen fixation by crop and pasture legumes in south-west Australia
Authors: Unkovich MJ , Pate JS , Sanford P , Armstrong EL
Published: November 2004

Precision of estimation of the proportion of legume N derived from N2 fixation (%Ndfa) was assessed in relation to subterranean clover (Trifolium subterraneum L.) pastures and crops of pea (Pisum sativum L.) and lupin (Lupinus angustifolius L.) under south-west Australian conditions. By using a standardized 10-point sampling procedure of paired sampling of legume and reference plant and reference plant 15N natural abundance (S15N) values in the range from +2.9 to +4. 0%o, %Ndfa of sample crops of lupin and field pea and a clover pasture were assessed with respective precisions of 93� O.6%, 76� 2.4% and 91�1.3% (� s.e., n = 10). Effects on S15N due to isotope discrimination during fixation and subsequent distribution of N by the three study legumes were studied using sand-cultured, fully symbiotic plant material. The resulting S15N data (B values) showed consistently more negative values for shoots than roots (all species), no significant effects of cultivar on B values (all species), a marked effect of rhizobial strain on B value (subclover) and a tendency for B values to fall with plant age (pea and lupin). The likely magnitude of errors in %Ndfa estimates due to incorrect choice of B value was indicated. By using data for reference plant S15N values from field surveys and previously assessed error factors in mass spectrometric measurement of S15N, precision of estimation of %Ndfa by using bulked material from the 10-point field sampling procedure was predicted for situations ranging from where a legume was obtaining only minimal amounts (10%) through to the bulk (90%) of its N by atmospheric fixation.
Selection of reference plants for 15N natural abundance assessment of N2 fixation by crop and pasture legumes in south-west Australia
Authors: Pate JS , Unkovich MJ , Armstrong EL , Sanford P
Published: November 2004

The 15N natural abundance (S15N) of the shoot total N of a range of non-N2 fixing potential reference species was compared with that of nodulated field pea (Pisum sativum L.), narrow leafed lupin (Lupinus angustijolius L.) or subterranean clover (Trijolium subterraneum L.) across a range of field sites, to which N fertilizers had not been applied in the season of study. Shoot S15N values of reference species lay mostly within the range from +3 to +5%o and there was some evidence of lower S15N values in gramineaceous than dicotyledonous non-legume species. Continuous sampling within crops of each legume showed S15N values to differ consistently between and within potential reference species through the season. The S15N values of seedlings of four non legume species in a lupin crop were closer to that of soil N03-N (S15N = 4.2%o) than soil NH4-N (S15N = 7.9%0). Shoot S15N values of non-nodulated pea, lupin and subterranean clover, and a range of possible reference species all sand-cultured on a defined nitrate source (S15N = 7.5%), suggested little or no discrimination during utilization of nitrate. However, when four candidate reference species were sand cultured with nodulated actively fixing subterranean clover on the same nitrate source, the S15N of the ryegrass was lowered significantly below that of the NO3. Field plot comparisons of nine potential reference species with nodulated field pea showed certain species to resemble field pea more closely than others in terms of the S15N value of their shoots. Reference plants sampled within or well outside the rooting zone of an actively fixing legume (subterranean clover, field pea or lupin) showed significantly lower shoot S15N of mixed grass components when harvested in root contact with, as opposed to well distant from, subterranean clover. A similar effect was observed for barley within v. outside the rooting zone of pea, but no such effects were observed between capeweed and subterranean clover, pea and radish, or for any of five reference plants matched with lupin. The data are utilized to select appropriate reference plants for field assessments of N2 fixation under south-west Australian conditions.
Passively-acquired antibodies to somatotropin release inhibiting factor (SRIF) increase appetite and growth of milk-fed lambs
Authors: Westbrook SL , Ali AM , McDowell GH
Published: November 2004

Lambs of ewes immunized during pregnancy against somatotropin release inhibiting factor and of corresponding control ewes were separated from their dams at birth before sucking and fed artificially, for 5 weeks, milk harvested mechanically from the ewes. Seven lambs from immunized ewes and six from control ewes were fed colostrum on the day of birth, and thereafter, milli from immunized ewes. A further six lambs from immunized ewes and seven lambs from control ewes were fed colostrum and milk from control ewes. Lambs fed colostrum then milk from immunized ewes, irrespective of whether their dams had been immunized, consumed more milk and attained higher growth rates, particularly during the period from 2 to 5 weeks after birth than lambs fed colostrum and milk from control ewes. Immunized ewes showed evidence for the capacity to produce more milk at improved efficiency of foodutilization than control ewes. It is concluded that passively acquired antibodies to somatotropin release inhibiting factor increased appetite and this, together with increased milk yield of immunized ewes, would support increased growth of lambs from immunized ewes.
Metallothionein and trace element metabolism in sheep tissues in response to high and sustained zinc dosages. 1. Characterization and turnover of metallothionein isoforms
Authors: Lee J , Treloar BP , Harris PM
Published: November 2004

Romney wether sheep were given ZnO on a regular basis, as required in protocols for the treatment of facial eczema, at either 12 g ZnO fortnight-1 or 12 g ZnO week-1, and the effect of Zn on the synthesis of different metallothionein (MT) isoforms isolated from liver tissue characterized and quantified. Metallothionein isoforms in liver of dosed and non-dosed sheep were quantitatively determined by reverse phase HPLC, with markedly increased concentrations of total MT-Ia protein found in the liver tissue of Zn-dosed groups (634 pg g-l fresh weight for the weekly dosed group) compared with 49 pg g-1 fresh weight in non-dosed sheep. The concentration of MT-II protein was not significantly increased. Individual sheep varied widely in the relative amounts of each MT isoform expressed with increased amounts of types of MT-Ia especially, and MT-I1 in some animals, which bound predominantly Cu. The half-lives for [35S]-cysteine and 67Zn in MT isoforms from weekly dosed sheep were found to be 2.5-3.5 days and 5-24 h respectively, indicating relatively fast exchange of Zn with MT compared with synthesis. Rate of synthesis for MT-Ia was twice that for MT-11. Data reflecting relationships between MT isoforms, Cu and Zn concentrations in liver are presented and discussed.
Effects of stocking rate in spring on liveweight and wool production of sheep grazing annual pastures
Authors: Thompson AN , Doyle PT , Grimm M
Published: November 2004

Two experiments examined the effects of different stocking rates in spring, and hence the availability of annual pastures, on changes in liveweight and wool production in Merino wethers (Experiments 1 and 2 respectively: age 5 and 2+-year-old; liveweight 63.8 � 0.64 (s.e.m.) kg and 43.8 � 0.34 kg; condition score 3.9% 0.14 and 3.l � 0-08). In Experiment 1, stocking rates were 8, 16, 24, 32 and 40 sheep/ha from 8 August, 1989 f9r 122 days; Experiment 2 involved an additional stocking rate of 48 sheep/ha from 23 August, 1990 for 98 days. Feed on offer (FOO kg DM/ha) declined (P < 0.01) linearly as stocking rate increased. Stocking rate and initial FOO (ranging between 1100 and 7000 kg DM/ha) had no significant effects on pasture growth rate (PGR) through most of spring. Late in spring, increased stocking rates resulted in greater (P < 0.05) PGR. The total amount of pasture produced in the grazing period was not significantly affected by stocking rate (Expt 1, 7530 to 8200 kg DM/ha; Expt 2, 6390 to 6860 kg DM/ha). The relationships between liveweight change (LWC) or wool growth rates (WGR) and FO, during the period until pasture wilting at the lowest stocking rate (83 days in Expt 1; 76 days in Expt 2), were described by Mitscherlich equations. More than 74% of the variation in LWC or WGR was explained by differences in green FOO. In Expts 1 and 2 respectively, more than 90% of the maximum liveweight gain (66 and 192 g/day) was achieved at a FOO of 4000 or 3000 kg DM/ha, and sheep maintained weight at 2000 or 1000 kg DM/ha. More than 90% of the maximum WGR (22.3 and 19.0 g/day) was achieved at a FOO of 3000 or 2000 kg DM/ha. More than 70% of the variation in WGR was explained by LWC in both experiments. The slopes of the linear relationships were 0.047 g wool/g LWC in Expt 1, and 0.024 g wool/g LWC in Expt 2. At liveweight maintenance, sheep produced 15% less (Expt 1) or 25% less (Expt 2) wool than those grazed under conditions which allowed maximum rates of liveweight gain. Fibre diameter (FD) and length of wool grown were affected in the same manner as WGR by increases in FOO and hence LWC. In Expts 1 and 2 respectively, total clean wool weights were reduced by 17 and 9 g, mean FD by 0.05 and 0.02 microns and staple length by 0.35 and 0.13 mm, for each increase of one sheep/ha during the spring treatment periods. The effects of stocking rate in spring on annual wool production, mean FD and staple length were described by linear (P < 0.05 to P < 0.01) relationships. Standard deviation of midside FD (Expt 2), staple strength and position of break (both experiments) did not change significantly with stocking rate. These results indicate that grazing to a lower FOO during spring can be used to manipulate the amount and characteristics of wool produced by Merino wethers grazing annual pastures in Mediterranean climates with 600-700 mm rainfall.
An abrasive pad rubbing method for inoculating sugarcane with sugarcane mosaic virus
Authors: Srisink S , Taylor PWJ , Stringer JK , Teakle DS
Published: November 2004

An abrasive pad rubbing method was developed for inoculating sugarcane plants with sugarcane mosaic virus (SCMV). This method involved moistening an abrasive pad with sap extract containing SCMV and carborundum, folding the pad around the base of the youngest fully expanded leaf, and pulling the pad towards the tip of the leaf. The abrasive pad method was as effective as, and much less laborious than, inoculating the spindle leaf by Sein's pricking method. Differentiation of resistant and susceptible sugarcane varieties was better when plants were inoculated at the advanced tillering stage than at either the 2-3 leaf or the tillering stages. In SCMV resistance trials done over 4 years with a set of eight 'standard' varieties, correlation coefficients of 0.92 to 0.99 were obtained for level of infection and disease ratings, indicating a high level of reliability of the rub inoculation method.
Evaluation of Bos indicus and Bos taurus straightbreds and crosses. II. Post-weaning growth, puberty, and pelvic size of heifers
Authors: Hearnshaw H , Arthur PF , Barlow R , Kohun PJ , Darnell RE
Published: November 2004

Post-weaning growth and body condition, puberty and pelvic size of 197 heifers comprising straightbred Hereford (HxH) and Brahman (BxB), first-cross (BxH) and back-cross (HxBH and BxBH) heifers were evaluated. The heifers were born over a 3 year period, and grazed improved and semi-improved pastures following weaning at Grafton, New South Wales. Prior to weaning, heifers had been reared by dams on three pasture systems (high, medium and low quality pastures). Heifers from low quality pre-weaning pasture had higher (P < 0.05) post-weaning liveweight gain than those from high and medium quality pastures. BxH heifers gained 71 g/day more (P < 0.05) than the mean gain of their contemporaries of the other genotypes, whose gains were similar, from weaning to either 26 or to 30 months of age. Liveweight at all ages was influenced by genotype x pre-weaning pasture system interaction. At 30 months of age, BxH heifers from high and medium pre-weaning pastures were the heaviest. At the same age, but from low quality pre-weaning pasture, heifers with crossbred dams (HxBH and BxBH) were the heaviest. Wither height depended significantly (P < 0.05) on the proportion of Bos indicus genes, increasing from 113.8 cm in the HxH heifers to 124.4 cm in the BxB heifers at 30 months of age. BxH heifers had a higher (P < 0.05) body condition score than their contemporaries of the other genotypes, which were in similar condition, at 26 and 30 months of age. On average (across pre-weaning pasture system), 9% of BxB heifers had reached puberty by 22 months of age compared to 62, 95, 82 and 64% (s.e.= 9) for HxH, HxBH, BxH and BxBH heifers respectively. No significant genotype differences were obtained in the height, width and size of the pelvic opening of the heifers, measured just prior to the beginning of the mating season at 26 months of age.
Immuno-modulation of hormones controlling growth
Authors: Wynn PC , Behrendt R , Jones MR , Rigby RDG , Bassett JR , Hoskinson RM
Published: November 2004

Consumer discrimination against meat products from animals treated with hormones has provided the impetus to investigate alternative ways of boosting feed conversion efficiency and growth rates of animals and to manipulate the reproductive capacity of animals. In view of the longevity of the immune response to specific antigens and the realization that antibodies are capable of neutralizing or mimicking the actions of hormones, vaccination techniques have been explored as alternatives to hormone administration to boost animal productivity. To date, only two commercial vaccines are available to improve the efficiency of production, although neither is related to the stimulation of growth efficiency: Fecundin (registered product, Glaxo Pty Ltd) is designed to improve lambing percentages, and Vaxstrate (registered product, Arthur Webster & Co.) to prevent reproductive activity. In this review, recent advances in vaccine development are explored together with some of the problems encountered in research in this field.
Effects of drought on leaf area development, biomass production and nitrogen uptake of durum wheat grown in a Mediterranean environment
Authors: Giunta F , Motzo R , Deidda M
Published: November 2004

A field experiment was carried out in Sardinia (Italy) on durum wheat to analyse the effects of different moisture treatments, irrigated (I), rainfed (R) and stressed (S), on leaf area index (LAI), radiation intercepted (Q) and water use (WU), efficiency of conversion of radiation and water into dry matter (RUE and WUE), nitrogen uptake and carbon and nitrogen partitioning in the above-ground part of the plant. In the period between beginning of stem elongation and heading, drought affected the maximum LA1 in the most stressed treatment (4.7 in S v. about 6.9 in R and I), but not Q and WU. RUE was also lowered by drought in this period (0.68 in S v. about 0.95 g MJ-1 in R and I) as a reduced biomass was recorded in S at heading (528gm-2 in S v. 777 g m-2 on average in R and I). In contrast with the previous period, the reduction in LA1 between heading and maximum ear weight (MEW) determined a significant reduction in Q and WU, WUE and RUE, resulting, ultimately, in notable differences in the total biomass produced until MEW (1203, 930 and 546 gm-2 in I, R and S respectively). The amount of stem reserves relocated to the grain decreased as the level of stress increased, going from 223gm-2 in I to 9gm-2 in S and was accumulated almost entirely (from 76% of the total in I to 100% in S), in the post-heading period. Nitrogen percentage was not affected by the treatments applied apart from the higher values in stem and flag leaf in S later in the growing season due to an inhibition of nitrogen translocation in S. The total nitrogen uptake was lower in S (12.3gm-2) than in I (16.6gm-2) only as a consequence of the different dry matter accumulation patterns. The importance of WUE in this type of Mediterranean environment is discussed, with particular concern to the key role of modulation of leaf area development through the growing season.
Studies on seed and pollen transmission of Alfalfa Mosaic, Cucumber Mosaic and Bean Yellow Mosaic Viruses in cultivars and accesions of annual Medicago species
Authors: Pathipanowat W , Jones RAC , Sivasithamparam K
Published: November 2004

Seed and pollen transmission of alfalfa mosaic (AMV), cucumber mosaic (CMV) and bean yellow mosaic (BYMV) viruses was investigated in annual medic species (Medicago spp.). For seed transmission studies with AMV, graft inoculation was used to establish early infection and maximize possible transmission rates to seedlings via seed, but with CMV and BYMV aphid and/or graft inoculation was used. For pollen transmission studies, pollen taken from virus-infected plants was used to pollinate healthy plants, the seed collected and seedlings tested. The rates of AMV isolate OUI-2 transmission to seedlings through seed produced on infected plants ranged from 6 to 53% for commercial cultivars and from 7 to 65% for accessions. Accession DZA 3181.1.1 of M. sphaerocarpos had the highest overall AMV transmission rate. Only two cultivars, cvv. Borung and Hannaford of M. truncatula, and accession SA 4268 of M. orbicularis, had transmission rates of less than 10%. The rates of CMV transmission to seedlings via seed produced on infected plants of the cultivars and accessions tested were 0.3 to 13%, the greatest being found in M. polymorpha cv. Serena, but 6 out of 11 had no detectable transmission. The rates of BYMV transmission to seedlings via seed of the cultivars and accessions tested were 0.3 to 1%, but in 12 out of 15 none was detected. AMV isolate OUI-2 was transmitted to 52% of seedlings via seed produced on healthy M. polymorpha cv. Circle Valley plants pollinated from infected plants. In contrast, no transmission to seedlings by either graft-inoculation or pollination of M. polymorpha plants was detected with a second AMV isolate, OUI-1, which appeared to have lost its ablilty to be seed transmitted. No CMV or BYMV transmission to seedlings via pollination of healthy plants with pollen from infected plants was detected in M. polymorpha cvv. Circle Valley or Santiago. When empty immature pods, and dissected seed coats and embryos from immature seeds produced on AMV-infected plants of M. polymorpha were tested, AMV isolates OUI-I and OUI-2 were detected in all pods and seed coats, but only in 59% of embryos with isolate OUI-2 and in none with isolate OUI-1. CMV was detected in 12% of embryos tested from immature seeds produced on CMV-infected M. polymorpha cv. Serena plants. Transmission of all three viruses through seed, and of AMV through pollen, is cause for concern in annual medic breeding and evaluation programs. Moreover, carry-over outside the growing season in medic pastures is possible through seed with all three viruses.
The role of allelopathy in legume decline in pastures. I. Effects of pasture and crop residues on germination and survival of subterranean clover in the field and nursery
Authors: Leigh JH , Halsall DM , Holgate MD
Published: November 2004

In a series of five trials, three conducted in the field and two in seed-flats in the nursery, it was shown that mulched residues from Phalaris aquatica and Triticum aestivum reduced the germination and production of Trifolium subterraneum. The deleterious effects observed with the mulched residues were not evident when the residues were incorporated into the upper soil layer. It is suggested that a reduction of the residues in pastures before the opening rains in autumn would be an essential requirement to ensure good germination and early seedling vigour from the annual legume component in mixed legume/grass pastures, especially those based on P. aquatica.
Effects of waterlogging, rootstock and salinity on Na, Cl and K concentrations of the leaf and root, and shoot growth of sultana grapevines
Authors: Stevens RM , Harvey G
Published: November 2004

Potted Sultana vines ( Vitis vinifera L. cv. Sultana) on own-roots or grafted onto Ramsey, Harmony, Schwarzmann or 1613 rootstocks were irrigated with solutions containing 1, 10, 20, 40 or 60 mM NaCl. Half the vines had free-draining rootzones and the other half were waterlogged for the first week in a 2-week cycle. The vines were harvested after seven cycles. Raising the irrigation salinity from 1 to 60 mM caused growth to decline by 47% in vines with free-draining rootzones and by 61% in vines with waterlogged rootzones. Under saline conditions, the use of chloride excluding rootstock reduced leaf chloride concentration by 60% in vines with free-draining rootzones but by only 18% in vines with waterlogged rootzones. Waterlogging decreased the root chloride concentration in all rootstocks. The leaf potassium concentration was reduced by waterlogging at irrigation salinities less than 20 mM NaCl and increased by waterlogging at higher salinities. Waterlogging altered the relative effects of rootstock on leaf potassium.
Geographical distribution and diversity in a collection of the tropical legume Macroptilium gracile (Poeppiga ex Bentham) Urban
Authors: Pengelly BC , Eagles DA
Published: November 2004

A collection of 53 accessions of the American legume Macroptilium gracile was grown and classified using 23 attributes. Ten groups from this extremely diverse collection were defined on the basis of the presence of amphicarpy (the ability to set both aerial and subterranean seed) and a small set of morphological and phenological attributes. The resultant classification has provided a framework for the selection of representative accessions from the collection for evaluation studies. Comparisons of provenance data from this collection and those of herbarium material from major North American herbaria highlighted both the lack of germplasm from the Caribbean region and poor representation of herbarium material from south of the Amazon basin. The variation in the collection supported the combination of M. longepedunculatum and M. gracile, but the morphological and geographic diversity suggests that the current taxonomic treatment should be revised.
Breakdown in resistance of subterranean clovers to clover scorch disease (Kabatiella caulivora)
Authors: Barbetti MJ
Published: November 2004

In spring 1990, in the Australasian Subterranean Clover and Alternative Legume Improvement Program field plots at Denmark, Western Australia, subterranean clover cultivars and crossbred lines normally highly resistant to clover scorch disease caused by Kabatiella caulivora, were severely affected by this disease. Testing the response of subterranean clover varieties to Kabatiella isolates taken from plants from these plots indicates the arrival of a new race of the fungus. The new race differs from all other isolates in overcoming the previously outstanding resistance of cultivars Green Range, Junee, Daliak and Esperance.
Genetic parameters for terminal sires estimated using data of progeny from Border Leicester × Merino ewes
Authors: Kenney PA , Goddard ME , Thatcher LP
Published: November 2004

Three and a half thousand lambs from Border Leicester x Merino ewes mated to 133 sires from five Poll Dorset, one White Suffolk, one Siromt, two Meridale and four Merino studs were slaughtered, their carcasses halved and one side divided into six primals. Subcutaneous fat was dissected from all six primals, and bone from only the three rear primals. There were four slaughter groups: average slaughter weights of 30 and 35 kg for ewes and 35 and 45 kg for cryptorchids. Heritabilities and phenotypic and genetic correlations for all traits measured (>50) are published in an appendix. Where comparisons were available, estimates were similar to those for purebred animals. Genetic parameters for various assessments of fat were similar except for channel and omental fat. The GR fat depth was the best predictor for total subcutaneous fat, cannon bone length for total bone, and eye muscle area for total soft tissue. Carcass weight and GR appear to be the most important measurements for use in selection for breeding of sires for the prime lamb industry. Slaughter weight and fat depth at the C site could be used as suitable alternatives on live animals. Production of lean meat is not likely to be increased greatly by including measurements other than liveweight and GR in a selection index. Of the other measurements bone length and eye muscle measurements showed most promise.