bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-term effects of level of dry matter intake upon milk yield, fatty acid composition of milk fat, and some blood constituents of Hereford cows
Authors: Stobbs TH , Brett DJ
Published: November 2004

The effect of two levels of feed intake (lucerne hay with mean digestible organic matter intakes (DOMI) of 6.1 and 9.1 kg/animal/day) on milk yield, calf growth rate, fatty acid composition of milk fat, and blood metabolites (non-esterified fatty acids and glucose) of suckled Hereford cows in their second and third month of lactation was measured to determine the most accurate indicators of intake of nutrients. Milk yields of cows averaged 5.0 and 6.1 kg/day on low and high intakes respectively, but production was extremely variable and poorly correlated with DOMI (r = 0.33). Calf growth rates were correlated with the milk yield of dams (r = 0.41) and with DOMI (r = 0.37). The fatty acid composition of milk fat provided the most repeatable (coefficient of variation of 6%) and reliable index of the feed intake, correlations being 0.71 with C4–C16 acids and –0.65 with oleic acid. Dry matter restriction decreased the proportion of C4–C16 acids (68.5% to 62.3%), while the proportion of oleic acid increased (17.0% to 21.9%). Cows responded rapidly to the level of feeding imposed, and no residual effects of previous feeding treatments were measured after 14 days. Non-esterified fatty acid levels in blood increased with restriction of feed (244–377 µ-equiv.11) and were poorly correlated (r = –0.16) with the intake, while the glucose content did not vary (mean of 70.6 mg/100 ml). It was concluded that the fatty acid composition of milk fat provides a reliable index of variation in the level of nutrient intake by suckled beef cows and could be used in short-term grazing studies.
The influence of defoliation on vegetation growth in swards of three strains of subterranean clover
Authors: Rossiter RC
Published: November 2004

Three defoliation regimes—uncut, defoliated every 14 days at 1.5 cm, and defoliated every three or four days (alternately) at 1.5 cm—were imposed on dense swards of Blackwood, Dwalganup and Daliak subterranean clover. The swards were grown in boxes, out of doors, at Perth from 1 June to 29 August. Mean daily solar radiation ranged from c. 1050 to 1450 J/cm2/day, and the average daily maximum and minimum temperatures were about 17° and 8.5°C respectively. The main finding was that defoliated swards yielded considerably less than uncut swards; averaging strains (and the two defoliated treatments) the decrease was c. 20% at day 33 and more than 40% at day 89. The lower yields of defoliated swards were associated with lower leaf area indices. During the first half of the experimental period, defoliation depressed growth in Blackwood more than in Dwalganup and Daliak. Uncut swards maintained the original plant density (28 plants/dm2), though some dead material was recorded in harvests at day 61 and (more particularly) day 89. Leaf area index exceeded 9 at day 89, with no clear optimum. Defoliated swards—especially those cut every three or four days—had more but smaller leaves, and higher branch numbers than uncut swards. In some respects these results conflict with those of previous reports, and explanations are proposed for apparent inconsistencies, mainly in terms of the temperature conditions.
Replacement of cv. Yarloop in swards by new genotypes of Trifolium subterraneum L. subsp. yanninicum and the effects of defoliation
Authors: Burch GJ , Andrews P
Published: November 2004

Yarloop is a waterlogging-tolerant cultivar of Trifolium subterraneum subsp. yanninicum; it is highly oestrogenic. It is known to be a strong competitor and is widely grown in south-western Australia. Three new low-oestrogenic, waterlogging-tolerant genotypes of subsp. yanninicum were grown in monoculture, and in binary mixture in competition with cv. Yarloop, in large boxes in a glasshouse. Of the three, Y111 and Y136 gave satisfactory growth relative to Yarloop, and exhibited similar flowering and seed production; cv. Larisa, a late-maturing type, performed well until flowering and had a lower seed number than Yarloop. A second experiment examined the effects of defoliation during the vegetative phase on the relative performance of cv. Yarloop and cv. Larisa growing in mixtures of varying proportions. Two overall densities were used. The dominance of Yarloop over Larisa in uncut swards, due to its more vigorous growth habit, was nullified by regular cutting. The agronomic implications of the results are discussed.
First record of Sclerotinia laxa Aderh. Ruhl. in New South Wales: differentiation from S. fructicola (Wint.) Rehm. by cultural characteristics and electrophoresis
Authors: Penrose LJ , Tarran J , Wong A-L
Published: November 2004

Sclerotinia laxa is recorded for the first time in New South Wales, at Orange. A survey indicates that the disease is confined to the Central Tableland. The disease was detected on Chaenomeles spp. (flowering quince), Prunus domestica (European plum), Prunus persica (nectarine) and several ornamental Prunus species (flowering cherries, apricot and peach). Cultural characteristics and acrylamidc-gel clectrophoresis were used to compare several of these isolates with isolates of S. fructicola from New South Wales and with S. laxa from Victoria. Isolates of S. laxa from South Australia and Tasmania were also studied in culture. The general colony lobing and the absence of hyphal anastomoses between germinating conidia can be used to identify S. laxa. Other cultural features found to be of little value for identification are discussed. The electrophoretic patterns for several enzymes clearly distinguished S. laxa from S. fructicola, and these representative reference patterns are useful for species identification.
The response of defoliated swards of subterranean clover to temperature
Authors: Greenwood EAN , Carbon BA , Rossiter RC , Beresford JD
Published: November 2004

The objective was to characterize the response of Trifolium subterraneum L. (cv. Daliak) swards to short-term and to long-term changes in temperature at several stages of plant growth. Short-term responses were studied with microswards growing in boxes in the open and defoliated every week to simulate heavy grazing. At seven stages, one subsample of boxes was harvested and three other subsamples were moved to controlled-temperature glasshouses and grown for 14 days at 10/5° (day/night), 17.5/12.5° and 25/20°C respectively, and then harvested. Dry weights and numbers of plant parts, and areas of leaves, height, light penetration and net carbon dioxide exchange of swards were measured. For long-term responses, young, defoliated microswards were transferred to the above temperatures for 9 weeks and cut weekly. On days 32 (pre-treatment harvest), 53, 74 and 95, tops and roots were harvested. The results support three generalizations. Firstly, severely defoliated subterranean clover pastures respond to temperature between 10/5° and 25/20° in a variety of ways over the whole life cycle. However, temperature is of greater importance as a determinant of dry weight of tops during the post-emergence and reproductive phases than it is during the preflowering phase. Secondly, total growth rate (TGR) after the first 8–10 weeks of growth does not increase at temperatures above 10/5°. And thirdly, even with moderately low LAI values of 1–4, temperatures of 25/20° can inhibit TGR after about 8 weeks of growth. The biological and agricultural implications are discussed.
Changes in the nucleic acid content of the uterus of sheep during involution following ovariectomy and following oestrogenic stimulation
Authors: Little DA , Lambourne LJ
Published: November 2004

The concentrations of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), in ovine uterine tissue were studied to determine whether the ratio RNA/DNA might be used in the bioassay of oestrogenic activity. As the uterus decreased in size with time after ovariectomy, the concentration of DNA increased markedly, but the total content of DNA in the uterus remained constant (mean value 342 ? 8 (SE) mg). The RNA concentration of the tissue decreased during involution, with the result that a highly significant reduction of 33% in the RNA/DNA ratio occurred within 2 weeks of ovariectomy. The ratio decreased further with time. Other ewes were treated for 3 days with diethylstilboestrol dipropionate (10 µg/day), commencing 2 weeks after ovariectomy; the stage of the oestrous cycle at which the ovaries were removed had no effect on the response to the oestrogen. Changes in the nucleic acid concentrations in the uteri of these ewes, and the results obtained during involution, indicate that the RNA/DNA ratio of uterine tissue in ovariectomized ewes has potential as a basis for the bioassay of materials of low oestrogenic potency.
Effect of methionine and lysine supplementation of diets for laying hens, on production and feed intake
Authors: McDonald MW , Bruce IJ
Published: November 2004

Six diets containing five levels of methionine and two of lysme were each fed to 12 Leghorn and 12 Australorp pullets for a period of 16 weeks Body weight changes, egg production, egg weight and feed intake were measured Although responses to the diets did not differ significantly In univariate analyses, multrvarrate analysis lndicated a srgnificant interaction between breeds and diets. Increased methionine produced small, significant Increases In egg weight, although responses were inconsistent at different levels Body weight gains were not significantly different between diets. Egg production and feed consumption were significantly affected by diet?, but the pattern of response was also inconsistent. A discriminate function analysis showed a consistent response to increased methionine, which indicated that the basal diet was deficient and that the pullets required a total of 0 275% methionine in their diet Lysine supplementation produced a 'significant decrease In feed intake but had no significant effect on any other variable.A multiple regression equation relating metabolizable energy intake to the variables measured in the experiment was calculated and compared with others reported In the literature This was used to predict the requirements of the pullets for a number of essential amino acids.
The interrelation of burr burial, seed yield and dormancy in strains of subterranean clover
Authors: Collins WJ , Francis CM , Quinlivan BJ
Published: November 2004

Prevention of burr burial drastically reduced the yield of viable seed in subterranean clover. This occurred through reductions in total burr number, number of mature burrs, number of seeds per burr, individual seed weight and seed viability. Strains differed markedly in their ability to produce seed in unburied burrs. A simple selection criterion based on changes in individual seed weight was proposed as a guide to screening for this character. When this criterion was applied to a wide range of strains, it appeared that later-maturing types were the most capable at producing seed in unburied burrs. The initial level of hardseededness was lower in seed from unburied burrs; also the rate of breakdown of hardseededness was faster in this seed, although the size of the effect varied between strains. Defoliation during the flowering period increased the initial level of hardseededness in seed from both buried and unburied burrs. Seed produced in buried burrs generally had a faster rate of breakdown of embryo dormancy than seed from unburied burrs, although the response varied between strains. The implications of these findings for future breeding and improvement in subterranean clover are discussed.
The response of the grape cultivar Crouchen (Australian syn. Clare Riesling) to various trellis and pruning treatments
Authors: May P , Clingeleffer PR , Scholefield PB , Brien CJ
Published: November 2004

An experiment IS dcsci bed which lasted for SIX seasons and was designed to investigate the response of the cultivar Qouchen (syn Clare Riesling) to various trellising and pruning treatments This cultivar, which achieves high levels of bud fruitfulness when grown In the Murray Valley, responded to widening the trellis from 0.3 m to 1.4 m with an increase In yield of 25–30%. This yield Increase was largely due to a better bud burst for vines on the wider trellis. Increasing the number of nodes per vine from 32 to 48 caused a yield Increase of about 15 %, but a further Increase to 64 nodes d i d not result in any additional yield response In the initial year of the trial, spur- and cane-pruned vines (with node numbers in the ratio of 4 to 5) yielded equally well. But In later years spur-pruned vines gave increasingly better yields, again resulting from differences In bud burst. To investigate the relationship between wine quality and yield, the fruit of four combinations of pruning and trellising treatments, giving a range of yields, was made into wine. Small-scale wine-making techniques were used No significant differences In wine quality attributable to the yield differences were found.
Urinary sediments in sheep feeding on oestrogenic clover. V.* Seasonal changes in the excretion of components of calculi and sediments
Authors: Nottle MC
Published: November 2004

Urine collections (24-hr) were made at 14-day intervals from early July to late October on six sheep grazing a pasture with oestrogenic Trifolium subterraneum cv. Dinninup dominant. Thin-layer chromatography was used to estimate urinary concentrations of formononetin, equol and 4'-O-methyl equol and to demonstrate the presence of benzocoumarins (urolithins A and B), biochanin A, indigotin and indirubin, which have been found in calculi or sediments from sheep grazing oestrogenic clover pastures. Formononetin levels ranged from 0.6 to 1.0mg% until late August and then from 1.2 to 1.7 mg %, the latter level occurring in late September. Equol concentration fluctuated between 8 and 15 mg % for the first eight collections but in the last two, in early and late October, levels reached 30 and 60 mg % respectively. The concentration of 4'-O-methyl equol ranged from 3 to 8 mg % until mid August and attained a peak of 29 mg % in late August. Between early September and early October values ranged from 15 to 23 mg % but by late October only trace amounts were present. Urolithin B appeared in all or most samples at each collection but urolithin A occurred in relatively few samples per collection until mid September. From mid September to late October the highest concentrations of both urolithins were attained. Indigotin generally occurred in only one urine at each collection but from mid August to mid September it was present in three or four urines per collection. Indirubin was present in all urines in all collections except the last, when it was present in only one urine. Biochanin A was detected only in urines collected in late September and early October. The relevance of these results to the period of formation of different calculi or sediments found in sheep grazing oestrogenic clover pasture and the implications of the metabolism of formononetin to equol and 4'-O-methyl equol in relation to urinary tract obstruction are discussed.

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*Part IV, Aust. J. Agric. Res., 26: 313 (1975).
The flow of nutrients from the abomasum in calves fed on heat-treated milks
Authors: Johnson RJ , Leibholz J
Published: November 2004

Three Friesian bull calves were fitted with re-entrant duodenal cannulae within the first week of life. Within 2 days of surgery the calves were allotted to one of four experimental diets: (1) fresh milk; (2) spray-dried low-heat whole milk powder (LS); (3) spray-dried high-heat whole milk powder (HS); (4) roller-dried whole milk powder (RD). At weekly intervals the calves were reallotted to another diet at random, so that each calf was fed for 1 week on each diet. The flow of digesta from the abomasum decreased as the time after feeding increased. When calves were fed once daily on the severely heat-treated milks (HS and RD), a more rapid flow of nutrients from the abomasum occurred in the first 12 hr after feeding, and a lower flow between 12 and 24 hr after feeding, than when they were given fresh milk or the LS milk. In the first 6 hr after feeding calves on fresh milk or LS milk a greater proportion of the casein nitrogen tended to be hydrolysed in the abomasum than in those fed on the HS milk. Subsequently the situation was reversed. The hydrolysis of fats in the abomasum was greater when the calves were given the severely heat-treated milks (HS and RD) than when they were fed on the other milks. Many of the changes observed may be related to the density of the milk clot formed in the abomasum.
Post-anthesis sink size in a high-yielding dwarf wheat: yield response to grain number
Authors: Fischer RA , Aguilar I , Laing DR
Published: November 2004

Experiments to study the effect of grain number per sq metre on kernel weight and grain yield in a high-yielding dwarf spring wheat (Triticum aestivum cv. Yecora 70) were conducted in three seasons (1971–1973) under high-fertility irrigated conditions in north-western Mexico. Crop thinning, shading and carbon dioxide fertilization (reported elsewhere), and crowding treatments, all carried out at or before anthesis, led to a wide range in grain numbers (4000 to 34,000/m2). Results indicated the response of grain yield to changing sink size (grains per sq metre), with the post-anthesis environment identical for all crops each year, and with all but the thinner crops intercepting most of the post-anthesis solar radiation. Kernel weight fell linearly with increase in grain number over the whole range of grain numbers studied, but the rate of fall varied with the season. Grain yield, however, increased, reaching a maximum at grain numbers well above those of crops grown with optimal agronomic management but without manipulation. It was concluded that the grain yield in normal crops was limited by both sink and post-anthesis source. There was some doubt, however, as to the interpretation of results from crowded crops, because of likely artificial increases in crop respiration on the one hand, and on the other, in labile carbohydrate reserves in the crops at anthesis. Also deterioration in grain plumpness (hectolitre weight) complicates the simple inference that further gains in yield can come from increased grain numbers alone.
Effect of phosphorus applied as superphosphate on rate of development and spikelet number per ear of different cultivars of wheat
Authors: Rahman MS , Wilson JH
Published: November 2004

The effects of adding phosphorus (40 kg of phosphorus ha-1) at sowing on rate of development, spikelet number per ear, rate of spikelet initiation, apex length at floral initiation, and leaf number at ear emergence of the main shoot of seven wheat cultivars were studied under a 16 hr photoperiod at a constant temperature of 20°C. Phosphorus additions increased the spikelet number per ear, rate of spikelet initiation, and apex length significantly in all wheats, but had no effect on the duration of the vegetative phase, spikelet phase or elongation phase, or on leaf number. The increase in spikelet number was due to an increase of spikelet initiation. All wheats responded similarly to addition of phosphorus.
Patterns of assimilate distribution in soybeans at maturity. II.* The time course of changes in 14C distribution in pods and stem sections
Authors: Stephenson RA , Wilson GL
Published: November 2004

Leaves at two levels in the canopy of determinate soybeans were allowed to assimilate 14CO2 at one of several stages of development from late pre-flowering until pod maturity, and the distribution of 14CO activity in above-ground parts of the plants was followed up to maturity. Between pre-flowering and early pod development, assimilate was stored in stems and transferred to pods during later development; at later stages, current assimilate went directly from leaves to pods. Carbon fixed subsequent to flowering went to pods in the axils of treated leaves, and to pods at the second nodes above and below fed leaves but not to adjacent nodes. The source of substrate for filling pods in the apical raceme was not apparent from this study.

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*Part I, Aust. J. Aguic. Res., 28: 203 (1977).
Selection against sprouting damage in wheat I. Germination of unthreshed grain, with a standard wetting procedure
Authors: Gordon IL , Derera NF , Balaam LN
Published: November 2004

An examination was made of germination events of non-dormant wheat grain, enclosed in the ear, and wet under repeatable conditions in a rain simulator. This formed one part of a study in which several aspects of phenotypic variability associated with germinability of wheat grain were examined. Following imbibition, the germination sequence was sprouting, endosperm degradation, and �-amylase response, which was relatively late in occurrence. Apparently, other germinative enzymes contributed substantially to first endosperm degradation. Selection criteria against sprouting damage were discussed with respect to these sample findings. Also, a sprouting damage score was found to be potentially useful for rapid selection amongst large numbers of populations.
Effects of sequential defoliation on lucerne (Medicago sativa L.)
Authors: Constable GA , Sheriden KP , Gleeson AC
Published: November 2004

The effects of the length of the defoliation period (sequential defoliation) on total matter yield, regrowth, root weight, root total non-structural carbohydrate (TNC) and root protein were measured over five growth cycles of glasshouse-grown lucerne. The treatments were: (1) control, complete defoliation 14 days after 10% flowering; (2) top half of plant cut on day 11 and the rest on day 14; (3) top half of plant cut on day 7 and the rest on day 14; (4) top third of plant cut on day 0, next third on day 7 and the rest on day 14. Sequential defoliation treatments reduced dry matter yields, by slowing down shoot regrowth and delaying phenologic development. The root weight of lucerne decreased as soon as tops were cut, and this loss was most evident with sequential defoliation treatments. Over the five growth cycles examined, treatment 4 plants maintained root size but had a significant decline in the percentage of TNC in roots. Those of treatments 1, 2 and 3 gained in root size and maintained the percentage of TNC in roots. Results support the management principle of keeping the grazing period of lucerne to a minimum by providing adequate subdivision of lucerne swards and by adjusting stocking rates. Levels of TNC over time might provide a useful tool for field studies in the development of management strategies for lucerne.
Genetic variation for seed yield, protein content, oil content, and seed weight in Lupinus albus
Authors: Green AG , Oram RN , Read BJ
Published: November 2004

The yield, protein content, oil content and weight of seeds of 14 lines of L. albus and of 232 F3 families derived from them have been determined in a favourable environment to assess the potential for the genetic improvement of this species. Yield and protein content exhibited wide variability around mean values of 1705 kg ha-l and 38.4% respectively. Their broad sense heritabilities were 57% and 83% respectively, and neither character showed significant variety x environment interaction when parental lines were grown in two contrasting environments which significantly affected the mean values. These characters were predicted to respond to selection, but progress would be hindered by a genetic correlation between them of –0.53. Oil content had a low mean (9.1%), high heritability (90%), but a low phenotypic variance, and hence would respond little to selection. It also was subject to variety x environment interaction. Seed size should respond readily to selection. No other unfavourable genetic correlations were found between flowering time, yield, protein and oil contents, and seed weight. Transgressive segregation was common in F3 families, many of which had lower protein, higher oil or smaller seeds than either of their parents.
The effect of sulphur on the growth, sulphur and nitrogen concentrations, and critical sulphur concentrations of some tropical and temperate pasture legumes
Authors: Andrew CS
Published: November 2004

Seven tropical and five temperate pasture legume species were grown in pots of three sulphur-deficient soils with varying additions of sulphate. Growth responses and the chemical composition of the plant tops were recorded, and from the latter, tentative critical concentrations of sulphur were established. These were compared with data from two field sites (six species only). Critical concentrations of sulphur in the tops of species sampled at the immediate pre-flowering stage of growth were: Macroptilium lathyroides 0.17%, Macroptilium atropurpureum 0.15%, Desmodium intortum 0.17%, Desmodium uncinatum 0.17%, Stylosanthes humilis 0.14%, Lotononis bainesii 0.15%, Glycine wightii 0.17%, Trifolium repens 0.18%, Trifolium semipilosum 0.17%, Medicago sativa 0.20%, Medicago truncatula 0.20% and Medicago denticulata 0.20%. Sulphate concentration and nitrogen/sulphur ratios were investigated as alternative diagnostic indices, but were not considered as suitable as total sulphur indices for the assessment of sulphur deficiency in legumes. Nitrogen concentrations in the plant tops were increased by sulphate supply, and excellent correlations were established between the nitrogen and sulphur concentrations in the plant tops.
Studies of seed-borne fungi of tropical pasture legume species
Authors: Nik WZ , Parbery DG
Published: November 2004

Fungi associated with seed of 22 tropical and three temperate pasture legume species were investigated and 42 species were isolated. Most species were obtained by using the blotter method, which required supplementing with procedures such as isolation onto potato dextrose agar and Nash–Snyder agar to ensure the isolation of as many species as possible from each seed sample. In order to isolate storage fungi, seeds were incubated on salt–malt agar. This medium was also effective in isolating pathogens which survived for long periods in seed, which suggests that such pathogens may share with storage fungi physiological characteristics which aid survival in seed. Eight species – Fusarium acuminatum, F. avenaceum, F. equiseti, F. fusarioides, F. oxysporum, F. poae, Diaporthe phaseolorum and Phoma sorghina – were proven pathogenic to a range of hosts, while four others – Botrytis cinerea, Cladosporium cladosporioides, Myrothecium leucotricha and an unidentified species of Fusarium – are regarded as possibly pathogenic and worth investigating. All species of Fusarium generally reduced emergence and root growth more than shoot growth although F. oxysporum reduced shoot growth more than emergence or root growth. F. equiseti was the most severe pathogen among the Fusaria and was also very common in seed samples. D. phaseolorum, not previously reported on Macroptilium, Stylosanthes or other leguminous hosts in Australia, caused serious damage to flowers and young pods, and seriously reduced seed set and altered the proportions of hard and soft seed in more mature infected pods. In infected pods most soft seed became infected and few infected seeds germinated. D. phaseolorum was isolated only from freshly collected seed, where it was present in embryo and cotyledonary tissue. P. sorghina caused leaf spotting and pod blight. Leaf infection caused reduction in root growth and a corresponding reduction in nodulation. Pod infections reduced seed set and produced a high proportion of infected seed. Infected seed generally failed to germinate. P. sorghina was also found in embryo and cotyledonary tissue and survived in infected seed for at least 5 years. One storage fungus, Aspergillus ruber, was a seed (embryo) pathogen. In freshly infected seed, germination resulted in abnormal seedlings. Seed infected for several months failed to germinate. Hard seed were generally free of storage and pathogenic fungi, while soft seed were commonly infected. Abnormal and damaged seed were the most likely to carry pathogens and other fungi.
Utilization of amino acids by preruminant lambs. I. The effect of alterations in total essential amino acid intake at constant nitrogen intake
Authors: Dove H , Pearce GR , Tribe DE
Published: November 2004

Male crossbred lambs weighing 12.5 kg (period 1), 20 kg (period 2) and 30 kg (period 3) were infused per abomasum with milk-based diets in which crude protein (CP) and energy contents were constant at a given Iiveweight, but in which the proportion of CP supplied as essential amino acids (EAA) varied from 120 to 876 g EAA/kg CP. Responses in liveweight gain, nitrogen balance and metabolizable energy (ME) intake (period 1 only) were measured. A number of lambs died while receiving diets containing very high or very low proportions of EAA. Possible reasons for these deaths are discussed. In all periods liveweight gains were greatest in lambs given the control diet (513 g EAA/kg CP). In period 1 this liveweight gain was close to that expected on the basis of energy intake, but in periods 2 and 3, liveweight gains on the control diets were less than anticipated. Reductions in liveweight gain were greater for diets containing low proportions of EAA than those containing high proportions. The infusion of diets containing low proportions of EAA markedly increased urinary nitrogen excretion. The effect of diets containing high proportions was less pronounced. As a result of these effects, lambs given the control diet had the highest daily nitrogen balance in all periods. Nitrogen balance was less severely affected by the dietary changes than liveweight gain, particularly with 30 kg lambs. It is suggested that the reduced retention of apparently digested nitrogen in diets other than the control diets reflected the unsuitability of the pattern of absorbed amino acids for protein synthesis. The effect of diet on the components of energy balance in period 1 was less pronounced than its effect on nitrogen balance. The metabolizability of apparently digested energy was lower in diets other than the control diet, especially those containing low proportions of EAA. This is attributed to the energy cost of increased urinary nitrogen excretion on such diets. Alternative interpretations of the results are discussed, and it is suggested that dietary amino acids will be utilized most efficiently for protein synthesis by the tissues of the lamb when essential and non-essential amino acids are provided in approximately equal proportions. There was no conclusive evidence that this optimum proportion was different for older lambs.
Changes in composition and pH of digesta along the gastrointestinal tract of sheep in relation to scouring induced by wheat engorgement
Authors: Lee GJ
Published: November 2004

Changes in the composition of digesta along the gastrointestinal tract of scouring sheep fed on wheat grain ad libitum were studied relative to sheep fed on lucerne hay ad libitum. Wheat engorgement significantly (P < 0.005) depressed the pH of the digesta in the reticulorumen and the digestive tract distal to the jejunum. A mean total volatile fatty acids concentration of 10.3mM in the caecum of scouring sheep was significantly lower than the mean of 51.6mM in sheep fed on lucerne hay. Net absorption of water was negligible in the colon of scouring sheep as digesta were only 13.7–14.7% dry matter, whereas in sheep fed on lucerne, the dry matter of digesta increased from 14.7% in the caecum to 27.9% at the rectum.
Influence of sward characteristics on grazing behaviour and growth of Hereford steers grazing tropical grass pastures
Authors: Chacon EA , Stobbs TH , Dale MB
Published: November 2004

Relationships between sward characteristics, grazing behaviour and growth of Hereford steers were studied on nitrogen-fertilized (378 kg ha-1 yr-1) Setaria anceps cv. Nandi and Digitaria decumbens swards continuously stocked at 4.3, 6.2 and 8.0 beasts ha-1 during five periods over 2 years. Availability of herbage, as measured by bite size, and nitrogen content and in vitro digestibility of herbage in the top of the swards were the two most important factors influencing the performance of steers. The relative importance of these factors varied between seasons, between stocking rate treatments and to a lesser extent between pasture species. The highest growth rates were measured on the leniently stocked pastures because steers were able to harvest feed easily (a large bite size) and could more readily select the more nutritious plant parts from the top of the sward. The swards were highly heterogeneous, and numerical analysis of data showed that at the same herbage yield, spatial distribution of herbage (leaf bulk density and leaf to stem ratio) and the nutritive value (in vitro digestibility and nitrogen content) of herbage greatly influenced the growth of steers. Cattle were unable to satisfy their feed requirements on some high quality but low-yielding swards, despite increasing grazing time to compensate for the small bites prehended (up to 707 min in 24 hr in spring). Consequently nitrogen and digestibility contents of extrusa samples were at times poor indicators of performance.
Effect of species and cultivation on the responses to phosphate of annual pastures and crops
Authors: Ozanne PG , Petch A
Published: November 2004

Three crop species, sand-plain lupin, Lupinus cosentinii L. (cv. Chapman), narrow-leaf lupin, L. angustifolius L. (cv. Uniharvest), and wheat, Triticum aestivium (cv. Gamenya), were grown under field conditions in soil fertilized then cultivated to 10 cm depth. Two annual pasture species, subterranean clover, Trifolium subterraneum L. (cv. Daliak), and Wimmera ryegrass, Lolium rigidum Gaud. (cv. Wimmera), were also grown in the field both with and without cultivation. All species were fertilized with seven levels of phosphate broadcast on the soil surface before cultivation. The amount of phosphate which produced 90% of maximum yield depended on species and cultivation practice: wheat required 98 kg phosphorus/ha; L. angustifolius, 65 kg/ha; L. cosentinii, 42 kg/ha; subterranean clover, after cultivation, 49 kg/ha; subterranean clover, not cultivated, 28 kg/ha; Wimmera ryegrass after cultivation, 40 kg/ha; Wimmera ryegrass, not cultivated, 18 kg/ha. All species except wheat required less current phosphate in this experiment than they did 3 years earlier on the same site in virgin soil. Cultivation changed the distribution of soil phosphate, and the roots of the pasture species followed the phosphate distribution.
The breed structure and genetic analysis of the pedigree Sahiwal breed in Australia
Authors: Herron ND
Published: November 2004

The breed structure and genetic history of the pedigree Sahiwal breed in Australia were analysed from registration data from the Society's Herd Book. It is stressed that the study is a special case—a new breed founded on 10 imported animals, numerically small, and still in its development stage. The breed structure was divided into four levels, with 10 imported animals at the top determining the genetic make-up of the breed. The genetic contribution of imported animals to the breed was 73.5%. Determination of the percentage direct relationship of important animals showed that several animals made a major contribution to the genotype of the breed. The maximum contribution of any one animal was 36.2%. Total inbreeding in 1974 was 21.2%. This comprised 5.6% current inbreeding, 8.3% long-term inbreeding and 7.3% strain inbreeding. The index of subdivision calculated from non-current and long-term inbreeding was 1.88, which indicated that there was little effective subdivision of the breed into separate strains. The effective generation length was 6 years. There was no selective registration of either sex.
The effect of fallowing on yield of wheat. III. The effect on grain nitrogen content
Authors: French RJ
Published: November 2004

The nitrogen content of wheat grain in the South Australian wheat-belt is related to water and nitrogen supply. Grain nitrogen decreased with increasing water supply; it tended therefore to be less in wet seasons, less under fallow because of additional stored water and less on fine-textured soils which also provided more water. Grain nitrogen increased as the nitrogen supply was increased either as additional nitrate due to fallow or as nitrogenous fertilizer. The effect of fallow on grain nitrogen varied with the season. In dry growing seasons, the grain nitrogen percentage was usually higher on the non-fallow treatment, because of the dominant effect of a lesser water supply. In moist growing seasons, the grain nitrogen percentage was higher on the fallow because of the dominant effect of a better nitrogen supply. Since rainfall is unpredictable, the net effect of fallowing on the grain nitrogen percentage is also unpredictable.
Repeseed adaptation in Northern New South Wales. II.* Predicting plant development of Brassica campestris L. and Brassica napus L. and its implications for planting time, designed to avoid water deficit and frost
Authors: Hodgson AS
Published: November 2004

Two experiments were conducted to determine the growing degree-day (D°) requirements of annual B. campestris and B. napus cultivars, and to evaluate their use in planning crop development strategies to avoid frost and moisture deficit at three locations. In the first experiment, base temperatures and D° requirements were calculated for four phases from planting to grain-filling, on the basis of linear temperature-development rate responses measured in the field at Tamworth, N.S.W. The phenological pattern of each species was predicted for several planting dates at locations representing the north-west slopes, northern tablelands and an intermediate region, by using long-term mean daily temperatures and calculated Do requirements. From these predictions and long-term mean daily rainfall and pan evaporation rates, the available soil moisture depletion was estimated for each planting date. For each location, planting date strategies for both species were evaluated for avoidance of frost and moisture deficit. The predicted optimum planting dates for B. napus and B. campestris were, respectively, 20 June and 5 August for the north-west slopes, 20 August and 1 October for the northern tablelands, and 30 June and 18 August for the intermediate region. In the second experiment, the influence of planting date on the grain yield of B. campestris and B. napus was studied in several seasons at each of the locations studied in the first experiment. The planting date that gave the highest yield varied between species and locations. B. campestris was favoured by later dates than B. napus. For both species these dates were earliest on the north-west slopes and latest on the northern tablelands. Yields of B. napus were higher than those of B. campestris at all locations when each species was planted at a favourable time. Predicted optimum planting dates from experiment 1 are discussed in relation to the field results from experiment 2.

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*Part I, Aust. J. Agric. Res., 29: 693 (1978).
Ecosystem processes in semiarid grasslands. I. Primary production and water use of two communities possessing different photosynthetic pathways
Authors: Christie EK
Published: November 2004

Above- and below-ground productivity and estimated evapotranspiration rates of a C3 native grassland and a sown C4 buffel grassland community growing on sandy red earth soils at Charleville were studied over a 12-month period. Resistance to water vapour transfer from leaves of both species was measured in the field and glasshouse. Although buffel grass had the highest maximum above-ground growth rate in summer, the most striking difference between the two communities was the much greater standing root crop and root production of the C4 community. Above-ground growth rates were very low in winter, and the differences in rates between communities were small. Over the summer growing period the water use efficiency of the C3 community was about 60% the value for the C4 community. Leaf resistance of the latter species was found to be greater under conditions of limiting and non-limiting water supply. The role of external factors influencing the distribution of these grasslands, as well as the agronomic implications of the study, are discussed.
The effect of defoliation on inflorescence production, seed yield and hard-seededness in swards of subterranean clover
Authors: Collins WJ
Published: November 2004

Swards of three strains of subterranean clover (Seaton Park, Yarloop, Midland B) were subjected to a range of defoliation treatments. In all strains, cutting at weekly intervals at a height of 1.5–2 cm from 1 month after sowing until the onset of flowering led to a slight delay in flower initiation but the time of flowering was little affected. The rate of inflorescence production, however, was always increased, as was the total number of inflorescences produced by the end of flowering. In particular, seed yields were increased by at least 30% compared with uncut controls. This effect was attributable partly to increased inflorescence numbers and partly to increases in other yield components as a consequence of the burial of a large proportion of burrs. Cutting increased the initial level of hard-seededness in Seaton Park and Yarloop; in addition the rate of breakdown of hard-seededness in all strains was slower in seed from the defoliated swards. When cutting was continued until midway through flowering (with the cutting height progressively raised) the seed yield in Yarloop and especially in Midland B was much lower than that obtained when cutting was stopped at the beginning of flowering; but in Seaton Park there was no reduction. With further cutting-until the end of flowering-seed yields were less than when cutting was stopped midway through flowering. Extending cutting into the flowering period (compared with cutting only until the onset of flowering) resulted in a decline in the initial level of hard-seededness and an increase in the rate of breakdown of hard-seededness in Midland B but had little effect in Yarloop or Seaton Park.
Corrigendum - The effect of defoliation on inflorescence production, seed yield and hard-seededness in swards of subterranean clover
Authors: Collins WJ
Published: November 2004

Swards of three strains of subterranean clover (Seaton Park, Yarloop, Midland B) were subjected to a range of defoliation treatments. In all strains, cutting at weekly intervals at a height of 1.5–2 cm from 1 month after sowing until the onset of flowering led to a slight delay in flower initiation but the time of flowering was little affected. The rate of inflorescence production, however, was always increased, as was the total number of inflorescences produced by the end of flowering. In particular, seed yields were increased by at least 30% compared with uncut controls. This effect was attributable partly to increased inflorescence numbers and partly to increases in other yield components as a consequence of the burial of a large proportion of burrs. Cutting increased the initial level of hard-seededness in Seaton Park and Yarloop; in addition the rate of breakdown of hard-seededness in all strains was slower in seed from the defoliated swards. When cutting was continued until midway through flowering (with the cutting height progressively raised) the seed yield in Yarloop and especially in Midland B was much lower than that obtained when cutting was stopped at the beginning of flowering; but in Seaton Park there was no reduction. With further cutting-until the end of flowering-seed yields were less than when cutting was stopped midway through flowering. Extending cutting into the flowering period (compared with cutting only until the onset of flowering) resulted in a decline in the initial level of hard-seededness and an increase in the rate of breakdown of hard-seededness in Midland B but had little effect in Yarloop or Seaton Park.
Corrigendum - Apical chlorosis and leaf spot of Tagetes spp. caused by Pseudomonas tagetis Hellmers
Authors: Trimboli D , Fahy PC , Baker KF
Published: November 2004

An undescribed apical chlorosis caused severe losses in seedlings of Tagetes erecta and T. patula types in Sydney, Brisbane and Melbourne in 1976. Bacterial leaf spots without chlorotic haloes invariably accompanied the disease. The same bacterium was isolated from leaf lesions and chlorotic tissue and produced leaf spots and chlorosis on marigold, zinnia and sunflower with spray inoculation. Leaf spots did not develop on T. signata. Apical chlorosis developed on a diverse range of plants following wound inoculation. The pathogen was shown to be seed-borne. The pathogen was identified as Pseudomonas tagetis, cultural and biochemical characteristics described, and a neotype culture proposed. An exotoxin was produced in vitro which caused apical chlorosis in Zinnia elegans and T. patula.
Resistance to water movement through wheat root systems
Authors: Seaton KA , Landsberg JJ
Published: November 2004

A three-layer electrical analogue model was used to calculate resistance to water movement through the roots of wheat plants growing in small weighing lysimeters. In one experiment the wheat was grown in two soil types; in a second experiment one soil type was used but different root systems were induced by controlling the water table before the start of the experimental period. Resistance calculations were based on hourly measurements of transpiration rate, leaf water potential and water uptake from three soil layers (qi), calculated from measurements of soil water potential at three depths. The number of main roots per stem (required for the model) and root surface area in each layer (Ai) were obtained from measurements of root lengths and diameters in soil cores taken at
the end of each experiment.
Estimates of the resistance to flow through stems led to estimates of ψ0), the water potential at the stem base, at any stem flow rate. Axial (main) root resistances (Rxi) were calculated from the Poiseuille equation. Values of the resistance to water movement through the roots in layer i were
calculated from the set of equations describing uptake from each layer in terms of flow rates, potential gradients and resistances; these values, inserted in the solution for 1/10 from the set of three equations, yielded total root resistances (RT) and estimates of the effective soil moisture potential (^ψs) for the whole profile. (RT) ranged from 63.9 to 627.3 bar sec mm-3 (cf. stem resistance between 24 and 70 bar sec mm-3) and was inversely related to flow rate through the main roots, which indicated a constant potential drop (^ψs – ψ0) of about 10 bars, irrespective of soil type or root system. Radial
root resistances, estimated as At(<ψsi – ψ0)/qi, ranged from 4.6 x 104 to 4.2 x 106 bar sec mm-l and were inversely related to qi.
Inaccuracies in estimates of Rxi do not affect the results much and the model used is potentially valuable as a framework for field research.
Distribution and dissemination of Mycosphaerella graminicola (Fuckel) Schroeter in relation to the epidemiology of speckled leaf blotch of wheat
Authors: Brown JS , Kellock AW , Paddick RG
Published: November 2004

The distribution of M. graminicola and the dissemination of ascospores in relation to the epidemiology of speckled leaf blotch of wheat in Victoria was studied. The fungus was present on wheat stubble throughout the Victorian wheat-belt and ascospores were discharged from stubble following periods of leaf wetness caused by rain or dew. Fertile perithecia were found on 1-year-old but not 2-year-old stubble. The viability of freshly ejected ascospores remained high throughout the growing season, and when shaded from direct sunlight ascospores remained viable for 1–2 weeks after release. The main period of ascospore discharge was late autumn to early spring, during which time the daily mean number of ascospores trapped 0.3 m above a commercial wheat stubble frequently exceeded 1000/m3 air.