bluuebunny/crossref_metadata_2025 huggingface dataset:
A simulation model of kenaf for assisting fibre industry planning in northern Australia. I. General introduction and phenological model
Authors: Carberry PS , Muchow RC , Williams R , Sturtz JD , McCown RL
Published: November 2004

The feasibility of utilizing kenaf (Hibiscus cannabinus L.) as a fibre crop and potential source of paper pulp is being investigated. This paper is the first in a series which develops and validates a simulation model of kenaf, and applies it to assessing the potential for dryland production in regions of tropical Australia. The duration from sowing to flowering is an important determinant of fibre yield in kenaf. Accordingly, the effect of temperature and photoperiod on the phenology of kenaf was examined. Data were collated from sowing-date experiments on kenaf cultivars Guatemala 4 and Everglades 71 at six locations in tropical Australia, ranging in latitude from 12� 54'S. to 19� 32'S. Data from one site, Kununurra, W.A. (15� 39'S.), was used to develop a model which described the duration from sowing to flowering in kenaf based on four stages: (1) sowing to emergence; (2) emergence to the end of the basic vegetative phase (BVP); (3) a photoperiod-induced phase (PIP) which ends at floral initiation; and (4) a flower development phase (FDP). Both kenaf cultivars responded as qualitative short-day plants where flowering did not occur above a critical photoperiod of 12.9 h. Assuming a base photoperiod of 12.0 h, the thermal time required to complete the BVP for the two cultivars was similar. However, photoperiod sensitivity during PIP, and the thermal time required for FDP, were greater for Guatemala 4 than for Everglades 71. Validation of the model against independently observed data for both cultivars at other sites resulted in close predictions in the thermal time required for flowering. This phenological model for kenaf can be used to assess the effect of sowing date on phenology at different locations in tropical environments, and is a key component of a crop growth simulation model to assess the environmental constraints to productivity in these regions.
Use of linear models to predict the date of flowering in cultivars of subterranean clover (Trifolium subterraneum L.)
Authors: Evans PM , Lawn RJ , Watkinson AR
Published: November 2004

Time to flowering (f) of eight phenologically diverse subterranean clover ( Trifolium subterraneum) cultivars was measured on nine sequential outdoor sowings in one season at Launceston, Tasmania, and one sowing date and four seasons in Perth, Western Australia. Linear models were then used to relate the rate of progress towards flowering (l/f) to mean temperature and mean photoperiod prevailing between sowing and flowering. The models accounted for most (70-97%) of the variation observed in time to flowering within cultivars, consistent with all of these cultivars being quantitative long day plants and photoperiodic effects being modulated by temperature. Model parameter estimates varied between cultivars suggesting genotypic variation for sensitivity to both photoperiod and temperature. The models and respective parameter estimates were subsequently used to predict flowering behaviour of the same eight cultivars in seven sequential sowings at Katanning, Western Australia. Across all 56 cultivarxsowing combinations at Katanning, there was a close (1:1) agreement between observed times to flowering and those predicted, with the models accounting for most of the observed variation. The models were least effective where times to flowering were longest, viz. for April sowings of the latest-flowering cultivars, where flowering tended to occur later than predicted. The potential utility of the approach is discussed in relation to cultivar improvement.
Evolution in sown populations of subterranean clover (Trifolium subterraneum L. ) in South Australia
Authors: Cocks PS
Published: November 2004

The seed banks of three pastures at Kingscote, Parndana and Waterloo, S.A., were sampled to determine the frequency of divergent genotypes in subterranean clover, and the direction of natural selection. The seeds were grown in nursery rows at Adelaide, and the resulting plants classified into one of the commercial cultivars, or as divergent genotypes. The divergent genotypes from one locality, Kingscote, were described in terms of 17 variables, and compared with strains collected from southern Australia and the Mediterranean basin. At each locality there was more genetic diversity than had been sown, both in terms of additional cultivars and the presence of divergent genotypes. The percentage of divergent genotypes appeared to be proportional to the age of the pasture, and was greatest at Kingscote, where it reached 67% of the population. The Kingscote genotypes were genetically related to Mt Barker and Dwalganup, only five out of 283 genotypes having leaf markings that differed from both cultivars. The 17 variables fell between the values recorded for Mt Barker and Dwalganup, and there was evidence of directional selection. For example, formononetin content was less, and genistein more than would be expected in the absence of natural selection. Mean flowering time was about equal to that of Seaton Park, and closer to Mt Barker than to Dwalganup. Flowering time was related to elevation above the lowest point in the paddock, the latest genotypes tending to inhabit sites at the foots of slopes, and the earliest genotypes sites on the tops. Seed and burr weight were slightly larger than expected. Hybridization was the most important, but not the sole source of genetic divergence at Kingscote, whereas contamination was the main source at Waterloo. It is likely that only a minority of the divergent genotypes was generated by mutation. The Australian subterranean clovers were as diverse as those from the Mediterranean. Those from Kingscote were also diverse, but, on the whole, had longer peduncles, shorter internodes and were taller than strains from other parts of Australia and from the Mediterranean basin.
Accumulation and partitioning of nitrogen and dry matter by contrasting genotypes of mungbean (Vigna radiata (L.) Wilczek)
Authors: Bushby HVA , Lawn RJ
Published: November 2004

The accumulation and partitioning of nitrogen (N) and dry matter (DM) by mungbean ( Vigna radiata (L.) Wilczek) were examined in a glasshouse experiment using three contrasting genotypes: a wild accession, a landrace cultivar and a recent commercial cultivar developed for mechanized agriculture. There was genotypic variation for all characteristics investigated. The landrace line accumulated N and DM at greater rates and to greater amounts than either of the other genotypes. However, yields of seed DM and N depended more on the harvest index (HI) and nitrogen harvest index (NHI) than on total biomass and total N accumulation, and both HI and NHI ranked commercial cultivar > wild genotype > landrace line. The three genotypes exhibited differing strategies for the partitioning of assimilates to seed. Seed production in the commercial cultivar occurred in two distinct flushes, with the immediate products of fixation and photosynthesis adequate to provide most of the requirements for N and DM for seed from the first flush. Seed from the second flush derived c. 37% of the N and 31% of the DM from remobilization of vegetative reserves. By contrast, 90% and 42% of seed N and DM respectively in the landrace line came from remobilization. The wild genotype was intermediate in that seed assimilates were concurrently derived from both N2 fixation, photosynthesis and remobilization. The implications for adaptation and further improvement in productivity through breeding are discussed.
Effect of sowing date and seeding rate on yield and yield components of irrigated canola (Brassica napus L.) grown on a red-brown earth in south-eastern Australia
Authors: Taylor AJ , Smith CJ
Published: November 2004

Response of canola (Brassica napus) to factorial combinations of five sowing dates and seeding rates was investigated from 1987 to 1989. The experiments were conducted on red-brown earths in the Goulburn-Murray Irrigation Region of south-eastern Australia. Crops were sown at monthly intervals beginning in April each year. In 1987, seeding rates were 4.6, 7.0 and 14 kg ha-1, but in 1988 and 1989 the lowest rate was eliminated. The cultivar Marnoo was used each year and Eureka was included in 1989. There was no difference between yields of seed and oil for crops sown in April and May, but yields of seed and oil declined when sowing date was delayed beyond May. Oil contents were greater than 45% for the April, May and June sowings in 1988 and 1989. In contrast, seeding rates had no effect on yields of seed and oil. Marnoo produced a maximum seed yield of 398 g m-2 from the May sowing in 1987, and a minimum seed yield of 172 g m-2 from the September sowing in 1988. In 1989, Eureka out-yielded Marnoo in all but the August sowing. Eureka produced a maximum seed yield of 483 g m-2 from the April sowing and its lowest seed yield of 315 g m-2 from the August sowing. The number of pods per m2 was the major factor responsible for the significant changes in yield in all experiments. Seed yield was also strongly correlated (P < 0.01) with biomass, and to a lesser degree, with individual seed weight in all comparisons with the exception of Marnoo in 1989.
Modelling the FFDA fibre diameter histogram of fleece wool as a mixture distribution
Authors: Gilmour AR , Atkins KD
Published: November 2004

The histogram of wool fibre diameters obtained by processing fleece samples through the Fibre Fineness Distribution Analyser (FFDA) machine is modelled as a mixture of two normal distributions fitted on the log scale (model iv). The paper compares this model with a single normal distribution on the natural scale (model i), a single normal distribution on the log scale (model ii) and a mixture of two normal distributions on the natural scale (model iii). When fitted to 2544 fibre diameter histograms from Merino hoggets, these models gave average lack-of-fits, distributed as �225, of 549.6, 190.1, 93.5 and 39.5 for models i to iv respectively. Model iv is proposed as the basis for describing the FFDA fibre diameter histogram in sheep breeding.
Seasonal variation in plasma metabolite and hormone concentrations, amino acid utilization and responses to Thyrotropin-releasing hormone in fleeceweight-selected and control Romney rams
Authors: Sun YX , Matthew TC , Blair HT , Harris PM , McCutcheon SN
Published: November 2004

Two studies were conducted to examine the effects of season on differences between the Massey University fleeceweight-selected and control lines of Romney sheep in hormone and metabolite concentrations, phenylalanine irreversible loss rate, urea and creatinine clearance and space, and response to an intravenous thyrotropin releasing hormone (TRH) challenge. Rams from the two lines were studied in autumn, winter and spring (5, 9 and 13 months of age) in Experiment 1 or winter and spring (9 and 14 months of age) in Experiment 2. Basal concentrations of urea and creatinine were lower in fleeceweight-selected (FW) than in control (C) rams in both experiments. A significant linexseason interaction, reflecting a greater difference between the lines in winter than in autumn or spring, was observed only in Experiment 1. This interaction could not be accounted for by a corresponding effect on distribution space or clearance of these metabolites. Phenylalanine irreversible loss rate (per unit metabolic body weight) was significantly lower in FW than in C rams, but the magnitude of this difference was not influenced by season (winter v. spring). No differences were observed between the lines in basal concentrations of thyroxine or triiodothyronine, or in the responses of these hormones to TRH. Prolactin response to TRH was lower in FW than in C rams during spring, but this reflected the higher pre-challenge concentrations of this hormone in FW rams. It is concluded that, compared with C rams, FW rams have lower basal concentrations of urea and lower irreversible loss rates (per unit metabolic body weight) of phenylalanine. However, these observations do not explain the less seasonal patterns of wool production in fleeceweight-selected compared with control sheep.
Low nodulation and N2 fixation limits yield of pigeonpea on alkaline vertisols of northern N.S.W.: effect of iron, rhizobia and plant genotype
Authors: Herridge DF , Holland JF
Published: November 2004

Pigeonpea grown on the alkaline black earths (vertisols) of northern New South Wales often fails to fix detectable amounts of nitrogen (N), resulting in N deficient crops and depressed seed yields. We aimed to solve this problem through selection of plant genotypes that were adapted to these soil types. Selection criteria included the agronomic characteristics of maturity (days to flowering), determinacy and seed size, and symbiotic characteristics of nodulation and N2 fixation. In addition, the interactive effects of fertilizer Fe and N, plant genotype and strain of rhizobia on those characteristics were examined. The experiments reported were sown between November 1988 and December 1990 on alkaline vertisols (pH range 7.9-8.2) at Tamworth, Currabubula and Breeza, N.S.W. In Experiment 1, 108 genotypes were inoculated with Bradyrhizobium strain CB756 and sown at two sites. Nitrogen fixation could not be detected for 86 of the 100 genotypes sown at the Tamworth Agricultural Research Centre and for 51 of the 62 genotypes sown at Currabubula. Six of the genotypes had Pfix (proportion of plant N derived from N2 fixation) values of 10-19% compared with values of zero for five of the six combinations of three check cultivars (Quest, Quantum and Campea)x2 sites. A further five genotypes produced seed yields up to 0.20 t/ha (14%) higher than the average of the three check cultivars. Effects of fertilizer Fe (applied at sowing as FeEDDHA at rates of 0, 0.25, 1.0, 4.0 and 16.0 kg Fe/ha) and N (as nitrarn at 0 and 200 kg N/ha) and strain of Bradyrhizobium sp. (CB756 and CB1024) on symbiotic and yield parameters of pigeonpea cv. Quest were examined in Experiment 2. Nodulation at flowering was increased by as much as 300% by Fe; by early pod-fill, effects of Fe has almost disappeared. Piix values were unaffected by Fe. Throughout growth, shoot dry matters increased with increasing rates of Fe, particularly when N was also applied. In the presence of fertilizer N, seed yields increased with increasing rates of Fe (1.67 t/ha at Fe0 to 2.43 t/ha at Fe16.0). Responses to Fe in the absence of N were reduced. Plants inoculated with rhizobial strain CB1024 outyielded plants inoculated with strain CB756 by 1.0 t/ha (Fe0) and 0.66 t/ha (Fe16.0). In Experiment 3, we examined the effects of fertilizer Fe on symbiotic and yield parameters of 14 genotypes of pigeonpea. There were significant differences between plant genotypes in nodulation, N2 fixation and yields of shoots and seed when fertilizer Fe was not applied and in responsiveness to applied Fe. Seed yields were increased by an average of 0.70 t/ha (108%) for highly responsive genotypes E33, M96, L133 and Campea, but only by an average of 0.32 t/ha (25%) for the low response group (E76, M48, MI44 and Quest).
Sowing date and varietal effects on the N2 fixation of field pea and implications for improvement of soil nitrogen
Authors: O'Connor GE , Evans J , Fettell NA , Bamforth I , Stuchberry J , Heenan DP , Chalk PM
Published: November 2004

Dry matter, biomass N, N2 fixation (determined by the 15N isotope dilution method), grain yield and grain N, were determined for five pea cultivars grown with three sowing times at six sites in south-eastern Australia. Earlier sowing (late April to early May) increased N2 fixation (by as much as 96 kg N/ha compared to sowing in late June to early July). Early sowing improved the probability of peas contributing to soil total N. The potential increment in soil N from the pea stubbles left after harvesting grain, averaged over the varieties, was as high as 98 kg N/ha with early sowing, and as low as -38 kg N/ha with late sowing. The benefits from earlier sowing were due to larger dry matter production with a higher N concentration and a greater proportion of plant N from N2 fixation. Varietal variation in fixed N and potential for augmenting soil total N, was generally smaller than the variation in these parameters due to different sowing dates.
Immunization of pregnant ewes against somatotropin release inhibiting factor increases growth of twin lambs
Authors: Westbrook SL , Chandler KD , McDowell GH
Published: November 2004

Multiparous ewes, pregnant with twin foetuses, were immunized with a complex of somatotropin release inhibiting factor/bovine serum albumin emulsified in Freund's Complete Adjuvant, or placebo on about days 90, 111 and 132 of pregnancy. At lambing, ewes with viable twin lambs and no obvious abnormalities were penned indoors with their lambs and fed restricted amounts of a good quality ration. Birthweights of lambs were greater for immunized than control ewes (4.6 v. 3.6 kg, P < 0.05) and 6 weeks later differences were maintained (13.6 v. 10.8 kg, P< 0.001). Liveweights of ewes from both groups were similar at parturition and 6 weeks later; even so, immunized ewes tended to lose more weight post partum than control ewes (10.9 v. 8.8 kg, P > 0.10). Milk yields of immunized ewes were 20-30% higher than those of control ewes during the 6 weeks post partum and milk of the immunized ewes contained lower proportions of lactose than in control ewes at day 14 of lactation. Feed intakes of both groups were similar, resulting in improved efficiency of use of food for milk synthesis in immunized ewes. Plasma concentrations of insulin were similar for both groups of ewes and lambs at all times, but plasma concentrations of glucose at parturition and 6 weeks later and urea during late pregnancy were reduced and concentrations of non-esterified fatty acids tended to increase during late pregnancy in immunized ewes compared with control ewes. The data are consistent with more efficient feed use by immunized than control ewes enabling greater foetal growth, increased milk yields and greater lamb growth.
Ruminant nutrition: reminiscences of Australian research
Authors: McDonald IW
Published: November 2004

The history of research on ruminant nutrition in Australia is recorded. A complex set of circumstances led to an abrupt origin in 1928 and rapid progress in the following years. A brief account is given of the major developments up to 1945. In spite of the fact that, during this period of 17 years, funds for research were very modest, a most impressive research output was achieved. One of the outstanding events was the discovery of the role of cobalt as an essential nutrient and the practical importance of cobalt deficiency in ruminants in Australia and many other countries. A detailed personal account is given of the early events in this research in order to establish due recognition of the original discoverers of cobalt's role in ruminant nutrition.
The development of ideas on the role of glucose in regulating milk secretion
Authors: Mepham TB
Published: November 2004

The author has reviewed the development of theories, over the last century, on the role of glucose in mammary metabolism, focusing on three overlapping issues, via. the extent of glucose utilization by mammary tissue, the synthesis of lactose, and the way in which glucose supply controls secretion of the aqueous phase of milk. In the first half of the century, deficiencies in technique produced several misleading results, and later progress resulted largely from methodological advances. Methodology has also been important in shaping research programmes, as is evident in the current emphasis on techniques of molecular biology. However, the review indicates the importance of employing a combination of experimental approaches, including whole-animal studies. Through the adoption of such approaches, it is now appreciated that glucose plays a key role in regulating lactation. It is suggested that developments over the last 30 years, which have led to formulation of an apparently resilient theory of milk secretion, conform to the notion of a 'progressive research programme' built on a 'positive heuristic', as proposed by the philosopher of science, I. Lakatos.
Rainfall patterns in a major wheat-growing region of Australia
Authors: Boer R , Fletcher DJ , Campbell LC
Published: November 2004

Rainfall is an important variable in the wheat production areas of Australia. This analysis examines, firstly, the pattern of rainfall over 2.3 million ha of a high-quality wheat-producing region, and secondly, develops regression equations for rainfall prediction over this region. Most of the variation in rainfall pattern across the region is accounted for by differences in October-to-March (summer) rainfall and in April-to-September (winter) rainfall. The summer rainfall differences account for over two thirds of the variation. Based on these two rainfall periods, a partitioning of the study area reveals five distinct regions. The second part of the analysis uses multiple regression to provide a set of equations for rainfall prediction at any location in the region, for a number of rainfall periods. These equations use altitude, longitude and latitude as predictors. Nearly all of the equations explain between 80% and 94% of the variation in rainfall. Differences between regions are accounted for in the analysis, making the equations widely applicable. The validity of the mean rainfall equations was tested on three further sites: the mean prediction error was 6.9%. This approach may be applicable where large land masses with similar geographical features occur.
Triticum tauschii: reaction to the take-all fungus (Gaeumannomyces graminis var. tritici)
Authors: Eastwood RF , Kollmorgen JF , Hannah M
Published: November 2004

Reactions of 398 accessions of Triticum tawchii to the take-all fungus [Gaeumannomyces graminis var. tritici (Ggt] were assessed. Nineteen accessions were selected for more detailed studies. T. tauschii accessions were identified that had less tissue blackening and more remaining green tissue when challenged by the fungus than the susceptible T. aestivum cv. Condor. However, tissue blackening in the T. tauschii accessions was much greater than that in Avena sativa cv. New Zealand Cape. Synthetic allohexaploid wheats produced from different Triticum turgidum var. durum (genome AABB) accessions and accessions of T. tauschii (genome DD) which had low tissue blackening or high remaining green tissue had more tissue blackening and less remaining green tissue than the T. tauschii parents. The potential of this material for breeding take-all resistant wheats together with experimental methods to minimize the possible confounding effects of seed weight, seed source and genetic effects are discussed.
Energy and growth
Authors: Lindsay DB , Hunter RA , Gazzola C , Spiers WG , Sillence MN
Published: November 2004

In this review we explore the relation between energy needs and growth. In the normal animal, we assume there are fixed values for the efficiency with which protein and fat are deposited. However, through modern technology, growth is increasingly being altered, either through the use of hormones, vaccines, or genetic manipulations. By examining the effects of such treatments (including different levels of feeding and the use of protein, steroid and catecholamine growth promoters), on the relation between protein and fat deposition, we attempt to determine how these treatments affect the efficiency of growth. What emerges from this review, is that each type of treatment (and in some cases individual compounds within a class) has a different spectrum of activity with respect to effects on food intake, the efficiency of protein and fat deposition, and the maintenance requirements of the animal. Moreover, the degree of variation in the efficiency with which available energy is used to deposit tissue, particularly protein, is shown to be marked. Whereas the size of this variation suggests that there is considerable scope for further improvements in domestic animal productivity through 'growth engineering', to make this progress, the cause of this variation needs to be better understood. Steps towards this understanding can be made by further studies on the mechanisms of action of available anabolic and catabolic hormones, and on their interactions with the sympathetic nervous system.
The effects of exogenous melatonin and prolactin on wool follicle development in ovine foetal skin grafts
Authors: McCloghry CE , Hollis DE , Foldes A , Rintoul AJ , Baker P , Vaughan JD , Maxwell CA , Kennedy JP , Wynn PC
Published: November 2004

The fleece of the Merino sheep is composed predominantly of wool fibres grown from secondary wool follicles. This study investigates the effects of melatonin and prolactin on the development of secondarv follicles in grafted ovine foetal skin. Skin from day 85 ovine foetuses was grafted onto nude mice, developed for 40 days and then excised. Mice received either 30 8g prolactin ip mouse-1 day-1 (P), one melatonin implant (Regulin�) sc mouse -1 (M), commencing at grafting or no further treatment (C). Wool follicle density and development were assessed in grafted skin and compared with day 125 control foetal skin. Cuticle structure of graft fibres was also examined and compared with those of day 125 foetuses. Total follicle density and the rate of follicle initiation were reduced in the grafts compared with control foetal skin. Total follicle density did not vary significantly between treatments, but the number of derived secondary follicles was greater in grafts from mice receiving prolactin (group P). Follicles in grafted skin were larger, produced medullated fibres, and were not grouped, in comparison with follicles in the control foetal skin. Epidermal thickness was greater in grafts than in control foetal skin. The cuticle structure of graft fibres from all groups was similar to the control wool fibres. These findings indicate that prolactin, but not melatonin, may be involved in the regulation of derived secondary follicle development.
Reducing post-partum anoestrous interval in first-calf Bos indicus crossbred beef heifers. 2. Responses to weaning and supplementation
Authors: McSweeney CS , Kennedy PM , D'Occhio MJ , Fitzpatrick LA , Reid D , Entwistle KW
Published: November 2004

Supplementation designed to increase the supply of glucose and amino acids, was compared with early weaning as strategies for reducing post-partum anoestrous in Bos indicusx Bos taurus (518x318) first-lactation heifers. Twenty-three pregnant heifers were allocated to four treatment groups and fed long-chopped hay (15.8 g N/kg dry matter) ad libitum and a complete mineral mixture throughout the experiment as well as 450 g molasses and 50 g urea per day during the final month of pregnancy. After calving, three groups were supplemented daily for 120 days with either 2 kg cracked rice (E), 0.4 kg formaldehyde-treated casein (P), or cracked rice (2 kg)+formaldehyde-treated casein (0.4 kg) (E+P); the unsupplemented control group had their calves weaned at 60 days post-partum. Supplemented animals had significantly higher intakes of hay (7- 1-7.3 v. 5.9 kg OM/day), weight gain (0.4-0.5 v. 0.0 kg/day) and body condition score (4.6-4.7 v. 4.3) than the unsupplemented heifers, but there were no differences between the supplemented groups in these variables. Unsupplemented animals and heifers fed P partitioned similar amounts of lactose and fat into milk, whereas secretion of both lactose and protein was significantly higher in the E+P and E groups. All control heifers ovulated within 14 days of their calves being weaned, whereas only two of the lactating supplemented heifers (EfP) showed cyclic ovarian activity at that time and three other lactating heifers ovulated several weeks later. The response to weaning occurred in heifers that had a liveweight and condition score of 374 kg and 4.3 respectively, which was 30-50 kg and a half unit in condition below the suckling heifers. In unsupplemented heifers showing ovarian cyclicity, acetate entry rate was less than half that of the supplemented animals, whereas glucose entry rate, adjusted for loss to lactose, was similar for both groups. Supplementation did not affect either the basal concentration or frequency of pulsatile release of luteinizing hormone (LH) at 60 days post-partum, or the LH response to gonadotrophin releasing hormone (5 8g GnRH). It is concluded that under the conditions of the present study, weaning had a greater effect than post-partum nutritional supplements on the resumption of ovarian activity in first-lactation heifers with moderate nutrition.
Changes within the digestive tract of sheep following engorgement with barley
Authors: Godfrey SI , Boyce MD , Rowe JB , Speijers EJ
Published: November 2004

The effect of feeding 1.4 kg of barley on the amount and composition of digesta in the rumen, small intestine, caecum, and colon was measured in sheep given either a gradual introduction to barley (over 8 days), no introduction, Yea Sacc (4 g/day for 9 days), virginiamycin (30 mg/day for 4 days) or rumen inoculum (600 mL/day for 4 days). The rumen pH was higher ( P < 0.05) and the number of sheep with high (> 5 mmol/L) levels of L-lactate and D-lactate significantly lower (P < 0.05) in sheep receiving no introduction compared to sheep receiving the gradual introduction to barley. Conversely the pH was lower (P < 0.05) and the molar proportion of L-lactate higher ( P < 0.001) in the caecum of the sheep receiving no introduction compared to sheep receiving the gradual introduction to barley. There was no difference (P > 0.05) in the incidence of ruminitis between treatment groups. Both virginiamycin and the transfer of rumen fluid from well adapted animals appeared to be as effective as the gradual introduction of barley in controlling L-lactate accumulation in the caecum and colon and maintaining the pH within these organs. The probiotic Yea Sacc did not appear to cause any changes in the pattern of fermentation and digestion when compared to the untreated control animals.
Evidence that each Rhizoctonia bare patch is dominated by an individual zymogram group (ZG) of Rhizoctonia solani AG-8
Authors: MacNish GC , Sweetingham MW
Published: November 2004

Studies of rhizoctonia bare patches in the southern part of the cereal belt of Western Australia indicate that each patch is dominated by an individual pectic zymogram group (ZG) of R. solani AG-8. R. solani was isolated from plants sampled from patches or from wheat seedlings grown in undisturbed soil cores removed from patches. The Rhizoctonia spp. isolated were characterized using electrophoresis in pectin-acrylamide gels. Four patch-forming zymogram groups (ZG1-1, ZG1-2. ZG1-4 and ZG1-5) were isolated. Of 121 patches examined, only five yielded more than one ZG. Two of these were due to the coalescing of two patches dominated by different zymogram groups. For the remaining three, there was only an occasional isolation of a ZG different from the dominant ZG. This may indicate a new infection focus endeavouring to establish in soil that another ZG occupies. Occasionally, patch-forming ZG1-1, ZG1-2, ZG1-4 and ZG1-5 were isolated from non-patch sites.
The effect of crop rotations and tillage practices on cadmium concentration in wheat grain
Authors: Oliver DP , Schultz JE , Tiller KG , Merry RH
Published: November 2004

The cadmium concentrations in wheat grain were determined from three crop rotation x tillage experiments in South Australia. Generally, the concentrations in grain were highest in wheat grown after lupins and lowest in wheat grown after cereal. The high cadmium concentrations in grain from wheat/lupins plots could not be explained solely by acidification, thus indicating involvement of other processes in cadmium availability. While cadmium concentration in grain also increased with increasing rates of nitrogenous fertilizers, the results of cultivation practices were generally too inconsistent to allow conclusions to be drawn. Cadmium concentrations exceed the maximum permissible concentration (MPC) of 0.05 mg kg-1 set by the National Health and Medical Research Council (NHWIRC) for unspecified foods in only one of the three tillage experiments. This study indicates that crop rotation is an important factor affecting cadmium uptake. Under certain soil conditions and with particular wheat varieties, the cadmium concentration in grain may exceed the MPC as the result of the crop rotation used.
The uptake of nitrogen by wheat, its agronomic efficiency and their relationship to soil and fertilizer nitrogen
Authors: Doyle AD , Holford ICR
Published: November 2004

Nitrogen uptake by wheat from both soil and fertilizer, and the efficiencies of fertilizer N (up to 116 kg/ha) for increasing yield and protein, were measured in 53 wheat fertilizer experiments during 1985-89 on the north-western slopes and plains of New South Wales. There was a highly significant (r2> 0.70) and common relationship between N uptake in unfertilized wheat (tops and grain) and soil nitrate to 90 cm depth for 4 of the 5 years of the study. A different but significant relationship occurred in 1988 when heavy rainfall before sampling leached some of the soil N beyond the sampled depth but within the rooting zone. The uptake and recovery of fertilizer N were lower in 1989, when in-crop rainfall was much lower than in the other 4 years. However, there was greater transfer of N from the herbage to the grain than in the wetter years. With increasing increments of fertilizer N. there was a much larger average decline in agronomic efficiency than in the recovery of fertilizer N or in physiological efficiency. Consistent with this, the average protein efficiency of fertilizer N tended to increase with increasing increments in every year except 1989. Although the highest increment of fertilizer N was always the least efficient for increasing grain yield, it exceeded the level required for profitability (8 kg grain/kg fertilizer N) in 20% of experiments. In experiments in which agronomic efficiency of the highest fertilizer increment was too low for profitability, there were at least 10 experiments in which the protein response was probably sufficient to make the highest increment profitable. The agronomic, protein and physiological efficiencies of fertilizer N in at least 10% of these experiments were higher than previously recorded in Australia and are comparable with the highest values recorded for wheat in other regions of the world.
Pre-harvest sprouting in wheat. I. Influence of cultivar, rainfall and temperature during grain ripening
Authors: Mares DJ
Published: November 2004

Tolerance to pre-harvest sprouting, measured by the response of grain in intact harvested ears to a standard wetting treatment, varied substantially from season to season and in all trials declined with time after harvest ripeness. The major factor associated with the observed variation in tolerance at harvest and the decline after harvest ripeness appeared to be the level of grain germinability. Statistical analyses of meteorological data relating to the 10- and 20-day periods prior to harvest and the period from harvest to wetting treatment, indicated that most of the seasonal variation in tolerance could be explained in terms of the amount of rain during the 20-day period prior to harvest. The potential to use this relationship to develop an early warning system for wheat growers together with implications for wheat breeding and cultivar improvement programs are discussed.
An economic evaluation of traditional twinning and sex-controlled systems of beef production in southern Australia
Authors: Herd RM , Bootle BW , Parfett DC
Published: November 2004

On a representative farm in southern Australia, the efficiency of beef production might be improved l.8 fold through changes in management practices and adoption of new techniques to induce twinning and to regulate the sex of calves born. Twenty-six modelled production systems were examined. Two of the three most efficient systems (kg meat per unit feed energy) produced crossbred calves, used twinning to produce more calves and sold them at yearling (18 months) rather than weaner (7 months) age. The other most efficient system was a single-sex all-female production system. Profit was calculated for each production system using a gross margins analysis (that is, total income minus variable costs). This, with the pattern of feed supply, feed consumption and labour use for each production system, was used in a linear programming model of a 'representative farm' to determine the optimum (most profitable) beef production system. Two of the three most efficient production systems were also the most profitable, being more than twice as profitable as the simplest traditional systems. The high cost of producing single-sex calves in the all-female system made it, and other systems using sex-control, unprofitable. Cows in systems with high net returns were very productive, had a high efficiency of lean meat production, but also a high feed requirement which forced a reduction in the optimum (most profitable) number of cows for the representative farm. Good management and attention to feed supply will be essential for these more profitable systems to be sustainable.
The productivity of lactating dairy cows fed irrigated Persian clover (Trifolium resupinatum)
Authors: Stockdale CR
Published: November 2004

A number of experiments were undertaken to establish the productivity of lactating dairy cows when offered green, vegetative Persian clover (Trifolium resupinatum) herbage and to study its utilization by these cows. The research included indoor feeding and grazing experiments and intensive metabolism studies. Levels of daily intake varied from 1.3 to 4.5 kg DM/100 kg liveweight and in early-to-mid lactation, milk yields as high as 30 kg/day were sustained. In early-to-mid lactation, marginal returns to additional feeding were 1.24 kg milk, 0.046 kg fat and 0.034 kg protein for each additional kg DM of Persian clover eaten by cows weighing 500 kg. In late lactation, marginal returns were 1.10, 0.050 and 0.035 kg/kg DM for milk, fat and protein, respectively. In a grazing experiment, utilization of herbage on offer was very high, ranging from 58-88% as grazing intensity increased. Consideration of the products of digestion suggested that fermentation of Persian clover herbage in the rumen resulted in a balance of metabolites that is unlikely to be detrimental to animal production. However, there were two aspects of rumen fermentation that could influence the potential utilization of the herbage. First, for much of the year, levels of ammonia in rumen fluid (up to 500 mg/L) were much higher than microbial requirements. Second, rumen fluid pH often dropped to about 5.5, a level which may inhibit cellulolysis. The implications of manipulating these aspects of rumen fermentation are discussed. It was concluded that, while few problems exist with the use of vegetative Persian clover for lactating dairy cows, this herbage may be used more efficiently if fed in conjunction with supplements that provide a better balance of nutrients for fermentation in the reticulorumen.
Compensatory growth in sheep and cattle. 1. Growth pattern and feed intake
Authors: Ryan WJ , Williams IH , Moir RJ
Published: November 2004

Sheep and cattle often exhibit compensatory growth following nutritional restriction. Complete compensation, that is the same weight at the same age as non-restricted contemporaries, has often been observed in sheep but not in cattle. In this experiment the compensatory growth of sheep and cattle was measured after their nutrition had been restricted sufficiently to induce losses in body weight. The growth, feed intake and feed conversion efficiency of the compensating sheep and cattle, measured during re-alimentation, was compared to control animals fed ad libitium throughout the experiment. A high-quality diet was used to maximize the opportunity for compensatory growth. The cattle exhibited compensatory growth for the 11 months between re-alimentation and the end of the experiment, and were able to compensate completely. Compensatory growth did not persist as long in the sheep as in the cattle, and they remained lighter than the controls at the end of the experiment. During the first 12 weeks of re-alimentation there was no difference in the feed intake of the compensating and control animals in both species. Compensatory growth during this time was due to the greater efficiency of the compensating animals. After this initial 12 weeks the feed intake of the compensating animals increased, and the subsequent compensatory growth could be fully accounted for by greater feed intake. The greater persistence of compensatory growth in the cattle was due to their intake remaining elevated longer.
Potential of using field spectroscopy during early growth for ranking biomass in cereal breeding trials
Authors: Smith RCG , Wallace JF , Hick PT , Gilmour RF , Belford RK , Portmann PA , Regan KL , Turner NC
Published: November 2004

The use of field spectroscopy for the non-destructive ranking of cereal breeding plots at the early stages of crop growth was investigated using measurements of spectral reflectance over 222 wavebands between 400 and 2500 nm using the single beam GEOSCAN Portable Field Spectroradiometer (PFS). Measurements were made on 54 barley plots at the 5- and 7-leaf stages of growth with biomass varying between 10 and 96 g/m2. The optimal multiple linear regression relationship between reflectance and biomass included wavebands from the near-infrared (NIR) and mid-infrared (MIR) with a standard deviation of 4.8 g/m2. The ranking of plots according to biomass by this optimal relationship or the Simple Ratio of NIR to visible (VIS) reflectance, which is a common index of greeness, agreed closely with actual ranking. Tested against an independent set of wheat plots at the 4-leaf stage with biomass ranging from 3 to 32 g/m2, the barley-derived relationship, but not the Simple Ratio, performed poorly in ranking plots according to biomass. However, at the 7-leaf growth stage, when the biomass range had increased to 48-117 g/m2, both the Simple Ratio and the barley-derived relationship agreed closely with the actual ranking. To apply these results in practice, the accuracy of the simpler CROPSCAN portable field radiometer (PFR) was found to be greater than the GEOSCAN PFS for comparable NIR and VIS wavebands. It was therefore concluded that it is practically feasible to use field spectroscopy to rank cereal plots for biomass at early growth stages where the difference between plots is of the order of 5-7 gm/m2. Such biomass differences were more apparent at the 7-leaf than 4-leaf stage of growth.
Functionality-Composition relationships of wheat flour as a result of variation in sulfur availability
Authors: MacRitchie F , Gupta RB
Published: November 2004

Some recently developed methods for analysing wheat protein composition have been applied to studying the composition/functionality relationships for flours from grain samples of the wheat variety Olympic, grown under differing nitrogen/sulfur fertilizer treatments. In this way, the effects of changing protein composition on functional properties could be followed without the complication of allelic variation. Previous work had established that sulfur deficiency caused an imbalance in dough properties characterized by an increase in dough strength (extensograph maximum resistance, Rmax) and a decrease in extensibility (Ext). In the present study, decreasing flour sulfur content was accompanied by an increase in the ratio of high (HMW) to low (LMW) molecular weight glutenin subunits. As a result, the portion of polymeric proteins (those proteins such as glutenins whose molecules contain multiple polypeptide chains) that is unextractable in SDS-buffer solution (%UPP, a measure of molecular size distribution) also increased with a decrease in sulfur content. A highly significant correlation was found between Rmax and %UPP. In contrast, Rmax showed a high negative correlation with the percentage of polymeric protein in the total protein. Results are generally in agreement with previous studies of wheat samples which varied considerably in genotype but not in environment, thus establishing fundamental relationships between protein composition and dough properties. Extensibility related positively to the percentage of polymeric protein in the flour, but evidence suggested that Ext can be limited by a shift in the molecular weight distribution to too high molecular weight. Reduction in the percentage of polymeric protein in flour (and Ext) as a result of sulfur deficiency was due to a decrease in LMW glutenin subunits which are normally present in greater amounts than the HMW subunits. Dependence of dough mixing and baking performance parameters on protein composition is also reported.
Corrigendum - National survey of viruses in pastures of subterranean clover. II. Statistical methodology for large scale quantitative ELISA
Authors: Muller WJ , Helms K , Waterhouse PM
Published: November 2004

Statistical methodology was applied to a survey of time-course incidence of four viruses (alfalfa mosaic virus, clover yellow vein virus, subterranean clover mottle virus and subterranean clover red leaf virus) in improved pastures in southern regions of Australia, with samplings in each winter and spring over 3 years. The 100 samples per paddock collected at each time of sampling provided detection probabilities of 0.63 and 0.87 for 1% and 2% infection respectively. A microtitre plate design for ELISA was developed to include 60 field samples, 10 glasshouse-grown healthy control samples and 6 glasshouse-grown samples infected with the virus under examination. This design was used on 816 plates for each of the four viruses tested. The method used for identification of virus in sap of a plant sample from a particular paddock was that the ELISA reading was both significantly greater than healthy control readings, and an outlier in the distribution of readings of all sap samples from that paddock. It is argued that as the identification of uninfected samples as infected was highly unlikely, this double criterion method was superior to the use of each criterion separately. Use of significance above healthy control values as the sole criterion would have increased virus incidences by about 60%; use of outlier identification as the sole criterion would have increased virus incidences by about 30%. A generalized linear model with binomial errors and logit link was used for adjusting the virus incidences reported in the previous paper (Helms et al. 1993) for biases due to paddocks and/or districts not sampled on some occasions. This adjustment slightly increased overall incidences in all but one sampling and confirmed the time-course increase in incidence over the 3 years of the survey. The same model also proved to be the most appropriate for investigating the effects of year, season and district on virus incidence.