bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of intraruminal infusion of urea on the response in voluntary food intake by sheep
Authors: Egan JK , Doyle PT
Published: November 2004

Six mature Merino sheep received three treatments in a randomized block design experiment. The treatments were: chopped oaten hay diet at 90% of ad libitum intake without urea (L); the ciet offered at the same level as for L with urea infused into the rumen at 11.5 g kg-1 dry matter intake (LU); and the diet offered at 90% of the ad libitum intake achieved with urea infused at 11.5 g kg-1 dry matter intake (HU). Sheep given HU consumed 37% more (P < 0.01) organic matter (OM) than those fed L or LU, but the apparent digestibility of OM did not vary (59.2-61.8%) between treatments. The addit onal food consumption was associated with c. 20% increase (P < 0.05) in the weight of OM in the reticulorumen and significantly higher (by 10-35%; P < 0.05) fractional outflow rates of most dietary and microbial constituents of digesta. The fractional digestion rate of potentially digestible plant cell walls was not affected by urea, but the flow of microbial non-ammonia nitrogen from the abomasum was enhanced (L, 7.0; LU, 8.2; HU, 12.5 g day-1; P < 0.05). The results of this study suggest that the stimulatory effect of urea upon food intake was associated with the provision of additional microbial protein for digestion in the intestines, rather than changes in the rate or extent of organic matter fermentation in the reticulorumen.
Tolerance of Trifolium subterraneum cultivars to low pH
Authors: Kim MK , Edwards DG , Asher CJ
Published: November 2004

Eleven cultivars of Trifolium subterraneum and Trifolium semipilosum cv. Safari were grown with adequate combined nitrogen for 27 days in flowing solution culture with controlled nutrient concentrations at constant pH values ranging from 3.5 to 6.5. A solution pH of 3.5 was lethal to all cultivars, but growth was in all cases vigorous at pH 4.0 (RGR 15.2-16.9 g 100 g-1 day-1). There were no significant effects of pH over the range of 4.0-6.5 on the yield of any clover cultivar. The results are discussed in relation to an earlier study suggesting greater tolerance of subterranean clover to pH values below 4.0. Phosphorus toxicity symptoms developed in all subterranean clover cultivars with the intensity of symptom development increasing with solution pH from 4.5 to 6.5. The concentration of phosphorus in the older leaves decreased as the solution pH was increased from 4.0 to 4.5, and then increased with further increase in pH, reaching values = 1.0%. Rates of phosphorus absorption followed a similar pattern of response to solution pH. Results are discussed with reference to previously reported effects of pH on phosphorus uptake.
Initial and residual effectiveness of molybdate fertilizer in two areas of south western Australia
Authors: Barrow NJ , Leahy PJ , Southey IN , Purser DB
Published: November 2004

A range of levels of sodium molybdate was applied to existing clover pastures at Boyup Brook and at Bakers Hill in south-western Australia. In the three subsequent years, further levels of molybdate were applied to some of the sites to assess the residual value of the initial application. The effect of the molybdate application on the molybdenum concentration in clover tops was measured. Plots of molybdenum concentration in tops versus molybdate applied curved upwards at first as each additional increment provided an increased response in concentration. However, at high concentrations of molybdate in clover tops the plots curved to the right at three out of four sites as each additional increment produced a decreased response. That is, overall, the curves were sigmoid. Increases in molybdate concentration were greatest on soils with least ability to retain molybdate as measured in the laboratory. Molybdate applied one year previously was about half as effective as currently applied molybdate. After two and three years it was about 20% as effective. A single application of rnolybdate remains effective for a long period on a soil of low ability to retain molybdate because the initial application is super-abundant - rather than because of large differences between soils in the rate of decline of effectiveness.
Tolerance of Phalaris aquatica L. lines and some other agricultural species to excess manganese, and the effect of aluminium on manganese tolerance in P. aquatica
Authors: Culvenor RA
Published: November 2004

Tolerance to excess manganese in 13 Mediterranean accessions and 3 Australian cultivars of phalaris was determined in solution culture with manganese concentrations from 0.5 to 210 ppm. The effect of aluminium (0, 2.5, 5-0 ppm) on the response of two accessions to excess manganese was studied in a second experiment. Phalaris was very tolerant to excess manganese. Shoot yield at 150 ppm manganese ranged from 25 to 50% of the maximum yield, which was achieved at 0.5 ppm in some lines and at 40 ppm in others. The cultivars Australian and Sirosa were among the most tolerant types. With one exception, Algerian accessions were the least tolerant. These accessions were of similar tolerance to Egret, the most tolerant wheat cultivar examined. All phalaris lines were much more tolerant than Isis wheat, Clipper barley, Woogenellup subterranean clover and Jumbuck rape. Variation in tolerance of high internal manganese levels was the principal determinant of relative tolerance within phalaris. Shoot manganese concentrations causing 10% yield reduction ranged from 730 to 2200 8g g-1 dry wt. The greater tolerance of phalaris compared with the other species was due to lower manganese uptake and higher internal tolerance. Presence of aluminium in the solution did not increase the susceptibility of phalaris to manganese toxicity. Aluminium strongly reduced manganese uptake in phalaris. It is concluded that selection for manganese tolerance need be only of low priority in developing a phalaris cultivar with improved tolerance of acid soils.
Diagnosis and prognosis of manganese deficiency in Lupinus angustifolius L
Authors: Hannam RJ , Graham RD , Riggs JL
Published: November 2004

Relationships diagnostic of manganese (Mn) deficiency in Lupinus angustifolius were examined in growth chamber experiments by studying the effects of Mn supply on plant growth and on photosynthesis and Mn concentrations in young leaves and whole shoots. A critical Mn concentration in youngest fully expanded leaves (YFEL) of 30 8g/g dry matter was found to be diagnostic of reduced dry matter production. A similar critical concentration was found for whole shoots, and the criteria were consistent over a wide range of ontogeny until at least early flowering. A less sensitive criterion of Mn deficiency was that for chlorophyll 'a' fluorescence characteristics of YFEL's (17 8g/g in YFEL), which estimates photosynthetic dysfunction in relation to Mn supply. The distal segments of lupin leaves best reflected changes in fluorescence in relation to their Mn status. The prognosis of impending Mn deficiency in maturing lupin plants was also examined in field and growth chamber experiments by studying the effects of Mn supply on the relationships between the concentrations of Mn in plant components at anthesis, and the subsequent appearance of Mn deficient ('split') seed on maturing plants. The absence of Mn deficient seed in main axis and first-order lateral inflorescences of maturing lupins could be predicted by Mn concentrations in stems at anthesis of >20 8g/g. Manganese concentrations of buds, leaves and tissues containing a high proportion of leaf, were found to be poor predictors of subsequent Mn deficiency in maturing lupins.
Effect of anthelmintic dosing and stocking rate on the productivity of weaner sheep in a Mediterranean climate environment
Authors: Brown TH , Ford GE , Miller DW , Beveridge I
Published: November 2004

The effects of nematodiasis on productivity in weaner sheep was measured at Kybybolite Research Centre, South Australia, during 1976-81. Three levels of control were compared at two stocking rates (7.5 ha-1 and 16 ha-1). One group was not treated with anthelmintics, another group was treated every 3 weeks and the third group (Planned) was given five doses of anthelmintics each year: once in October, twice during the hot dry summer and twice during the winter months. The sheep were replaced by weaner sheep at shearing in October each year. The drenching regime of sheep on a particular paddock was the same for all five years. Nematodes, particularly Trichostrongylus spp., had a very large effect on the production of the sheep. The mean annual death rate of the untreated sheep was 22% and 56070, for the low and high stocking rates respectively. The regularly drenched sheep were 9-31% heavier and cut 11-46% more wool than the survivors of the untreated sheep at the low stocking rate. At the high stocking rate the regularly drenched sheep were 17-58% heavier and cut 14-56% more wool than the survivors of the undrenched sheep. The sheep given the Planned drenching program had similar final liveweights each year to the regularly drenched sheep, and in only two years out of five did the regularly drenched sheep produce significantly more wool than the sheep given the Planned program. The effect of drenching on the contamination of wool with faeces, and the resultant effect on the incidence of fly strike, is discussed. There was a significant variation between years in amount of available pasture, and there was generally slightly more pasture available on the Nil drench treatment paddocks.
Mortality in weaner sheep in South Australia under different regimes of anthelmintic treatment
Authors: Beveridge I , Brown TH , Fitzsimons SM , Ford GE , Judson GJ , Martin RR , Miller DW
Published: November 2004

Causes of mortality in weaner sheep subjected to differing regimes of anthelmintic treatment were investigated at Kybybolite, S.A., between 1976 and 1981. The greatest mortality occurred in untreated sheep during the winter months, and was directly attributable to nematode infections, principally Trichostrongylus vitrinus. Deaths occurred during the summer months of the later years of the experiment. Nematode infections were considered to be a predisposing cause, with anaemia possibly due to infection with Eperythrozoon ovis as the precipitating factor in mortalities.
Occurrence and identity of barley yellow dwarf viruses in Tasmanian pasture grasses
Authors: Guy PL , Johnstone GR , Duffus JE
Published: November 2004

A total of 1048 pasture grass plants representing four species was sampled from five different sites in Tasmania and tested for infection with viruses known to infect them in other temperate regions of the world. The species were cocksfoot (Dactylis glomerata), tall fescue (Festuca arundinacea), perennial ryegrass (Lolium perenne), phalaris (Phalaris aquafica) and timothy (Phleum pratense). The only viruses isolated from the plants sampled were two luteovirus types which were recovered by aphids and caused symptoms of barley yellow dwarf (BYD) in oat indicator plants. A total of 140 plants (13%) were infected. One plant was infected with a vector specific RPV type [transmitted only by oat aphids (Rhopalosiphum padi) and serologically like the New York type RPV isolate], 138 were infected with PAV types (vector non-specific and serologically like the New York type PAV isolate) and one plant apparently contained a mixed PAV/RPV infection. The PAV isolates varied considerably in the intensity of symptoms which they induced in oat indicator plants. Viruses were isolated only from tall fescue and perennial ryegrass plants in this survey. The initial recovery of BYD isolates with oat aphids and with blackberry-cereal aphids (Sitobion fragariae) from the pasture samples was often not a good indication of their serological specificities, particularly in young pastures. These data provide the first information on the vector specificities of viruses which cause BYD in Australia and on their serological identity.
Studies on the behaviour of furalaxyl on pythiaceous fungi and cucumbers in recirculating hydroponic systems
Authors: Price TV , Fox P
Published: November 2004

Etridiazole and furalaxyl inhibited growth of Pythium irregulare in agar at 0.1 and 1 mg l-1, respectively, but sporulation was not inhibited by 10 and 5 mg I-'. In stationary hydroponic nutrients, recovery of P. irregulare declined with increasing concentrations of etridiazole and furalaxyl above 10 mg l-1 and with increasing duration of exposure to concentrations below 10 mg l-1. Zoospores of Phytophthora cryptogea were dispersed throughout recirculating nutrient film (NFT) systems, but few were recovered by plating nutrients sampled 1 h after inoculation. The fungus was detected by baiting nutrients up to 5 days after inoculation, but was not detected in nutrients treated with 20 mg l-1 furalaxyl. Concentrations of furalaxyl in the NFT system declined by 50% over 7 days. Furalaxyl significantly increased sodium levels in the NFT nutrients. Cucumber plants growing in furalaxyl-treated nutrients contained significantly higher levels of sodium and iron and decreased levels of zinc; fruit yields were significantly decreased but there were no effects on leaf or stem dry matter. Disease did not develop on cucumber plants growing in an NFT system inoculated with P. cryptogea. Pot experiments indicated the fungus was pathogenic at temperatures of 10/15�C, and seed treatment with thiram was ineffective in controlling the pathogen. The management of P. cryptogea in NFT systems by furalaxyl or controlled environments is discussed.
Heterosis and breed effect on carcass traits of rams. II. Carcass adiposity traits
Authors: Ch'ang TS , Hood RL , Evans R
Published: November 2004

A total of 632 intact rams comprising three purebreds (Dorset Horn, Merino and Corriedale) and their six contemporary F1 crossbreds produced during phase I of the CSIRO Sheep Crossbreeding Experiment were used in the study. The rams were slaughtered at an average age of 21 months, at which time their average (� s.e.) carcass weight was 28.4 �0.2 kg. This paper, the second in the series, is concerned with estimation of the linear effects due to heterosis (hI), breed-transmitted effect (gI) and breed-maternal effect (gM) on four adiposity traits: perirenal fat weight, subcutaneous fat depth, percentage ether extract of m. semimembranosus and adipocyte diameter from the perirenal fat sample. The results showed that, in general, breed-transmitted effects are relatively more important than breed-maternal effects in accounting for breed differences in adiposity traits. Further, data based on all the adiposity traits under investigation are consistent in placing the Corriedale as the 'fattest' of the three purebreds studied. The hI effect is variable, depending on both the trait and the breed combination. Thus, perirenal fat weight (%hI = 22.6) and subcutaneous fat depth (%hI = 13.9) are both more heterotic than percentage ether extract (%hI = 1.6) or adipocyte diameter (%hI = 2.8). In every trait, the estimates of hI are lower in value (actual unit or as a percentage) for the Merino-Corriedale breed combination than for either the Dorset Horn-Merino or the Dorset Horn-Corriedale breed combination, demonstrating the importance of breed as a source of variation in heterosis effect.
The decline in the availability to plants of applied copper fertilizer
Authors: Brennan RF , Gartrell JW , Robson AD
Published: November 2004

The availability of copper sulfate for uptake by wheat plants declined linearly with time over 13 years of contact between the soil and the applied copper for a yellow brown lateritic sandy earth in a semiarid mediterranean environment. A steady decline in both the copper concentrations of the youngest emerged blade (YEB) and copper content in shoots of wheat plants resulted with increasing time of soil contact. For all copper additions, a linear model was fitted to the decline in YEB copper concentrations with time. This model predicts that copper deficiency would be observed 18, 30 and 44 years after the application of the 2.75, 5.5 and 8.25 kg copper sulfate/ha at this site.
The high-molecular-weight glutenin subunit composition of Australian wheat cultivars
Authors: Lawrence GJ
Published: November 2004

The seed storage proteins of 106 Australian wheat cultivars were fractionated by sodium dodecyl sulfate polyacrylamide gel electrophoresis to determine the allelic composition of the cultivars at each of the three loci controlling high-molecular-weight (HMW) glutenin subunits. Amongst the cultivars, three alleles were identified at the Glu-A1 locus, eight at the Glu-B1locus and four at the Glu-D1 locus. The results are presented in the form of a key to aid identification of unknown samples. Sixteen of the cultivars were found to consist of two or more biotypes with respect to HMW glutenin subunit composition.
The effect on yield distribution of early generation selection for quality
Authors: O'Brien L , Ronalds JA
Published: November 2004

In simulation of a wheat-breeding situation, random F3 lines derived from seven wheat crosses were quality tested, and decisions to retain or discard them were made on the individual test results for flourmilling extraction, flour protein content and four separate measures of protein quality. Decisions were also made using regimes of tests that selected entries for high flour extraction and their balance of grain hardness, protein content and quality optimum for different wheat end-uses (bread, cakes, pastries, etc.). In the F4 generation all entries were grown in replicated yield trials. The effect of early generation selection for quality on the subsequent yield distribution was assessed by comparing the F4 yield distributions of the entire population with those for the designated quality test. Independent culling for flour-milling extraction and protein quality did not alter the nature of the subsequent yield distributions. However, independent culling in the F3 for flour protein content resulted in the loss of more lines of above average yield than below average yield in the F4 generation. Furthermore, the significant negative correlation between F3 flour protein content and F4 grain yield indicates that overemphasis on selection for high protein content would reduce the rate of yield improvement in the following generation. Application of the early generation testing regimes resulted in up to 66% of the lines being classified as having undesirable quality without the nature of the subsequent yield distribution being affected. The results of this study have application to the planning of wheat-breeding programmes that aim to produce high-yielding, good-quality wheats.
Nutritional evaluation of south-west Queensland pastures. 2. The intake and digestion of organic matter and nitrogen by sheep grazing on Mitchell grass and mulga grassland associations
Authors: McMeniman NP , Beale IF , Murphy GM
Published: November 2004

The intake and digestion of organic matter and nitrogen by sheep grazing two Mitchell and one mulga/ grassland association was studied under a variety of seasonal conditions. The in vitro digestibility of the diets selected by sheep grazing both pasture types was in the range 60-70% when seasonal conditions were good, but fell to 52.3% and 48.2% for the Mitchell and mulga/ grasslands respectively when the pasture were dry. Digestible organic matter intakes of intact sheep grazing the Mitchell grass pastures were 14.0-16.3 g (kg W)-1 day-1 when seasonal conditions were average to good and 13.5 g (kg W)-1 day-1 after the pastures had dried out. Comparable figures on the mulga/grassland pastures were 17.8-18- 1 g (kg W)- day- with good seasonal conditions and 11.8 g (kg W)-1 day-1 with dry pasture. The nitrogen concentrations in the diets varied from 7 to 26 g/kg OM on the Mitchell grass associations and from 17 to 34 g/kg OM on the mulga/grassland. Apparent digestion of dietary N within the rumen ranged from 70% to 90% on both sites when there was green forage in the diets, but fell to 58.5% and 37.6% on the Mitchell and mulga/grassland respectively when the pastures were drought affected. Under the latter conditions the quantity of amino acid N absorbed from the small intestines was depressed at both sites, as was the efficiency of microbial N production in sheep grazing the Mitchell grass pastures. These findings are discussed in relation to the protein and energy requirements of sheep grazing the two pasture associations.
Genetic variability for manganese concentration in Phalaris aquatica growing in acid soil
Authors: Culvenor RA , Oram RN , David DJ
Published: November 2004

High levels of manganese in forage can retard the growth of livestock. The feasibility of breeding for lower manganese concentration in shoots of phalaris was examined in a variable population growing in acid, manganiferous soil. Sampling leaves of a particular physiological age in a field-growing breeding population provided an adequate indicator of manganese concentrations in whole shoots. Significant family differences were demonstrated. When transferred to sand culture, high manganese selections maintained consistently higher tissue manganese concentrations than low manganese selections over a wide range of manganese treatments. However, the range of variation was much smaller than in the field. Inheritance of manganese concentration was studied in 52 field-grown half-sib families and their parents from the breeding population. Mean family leaf sample concentrations ranged from 179 to 331 8g Mn g-1. Narrow-sense heritability estimates were 0.72 from the half-sib analysis and 0.40 from the parent-offspring relation. The former estimate is considered the more accurate, because the parent-offspring estimate was depressed by high random variation in some parent means. The mean manganese concentration of the population is predicted to decrease by approximately 80 8g g-1 in each generation in which progeny are raised only from those 25% of plants with the lowest manganese concentration. Although this estimate may have been influenced by available soil aluminium, it indicates that breeding for lower manganese concentration in phalaris is feasible.
The relationship between vegetative and reproductive development in the mango in northern Australia
Authors: Scholefield PB , Oag DR , Sedgley M
Published: November 2004

Vegetative and reproductive growth was recorded on mature mango trees (cultivar Kensington) over two years in northern Australia. There were four vegetative growth flushes during each year, but not all shoots grew during each flush. Observations on the flowering of shoots of known age showed that the older shoots produced most inflorescences. Microscopic examination of terminal buds showed that floral initiation occurred within a month of the commencement of the flowering flush under these tropical conditions. The main vegetative growth flushes occurred prior to flowering between March and May, and during flowering and early fruit development in July and August.
Differences in natural abundance of 15N in the extractable mineral nitrogen of cropped and fallowed surface soils
Authors: Turner GL , Gault RR , Morthorpe L , Chase DL , Bergersen FJ
Published: November 2004

The natural abundances (S15N with reference to atmospheric N2) of the stable isotope of nitrogen (15N) in the total nitrogen and in KCl-extractable mineral nitrogen (typically 96% NO-3-N and 4% NH+4-N) were measured in the surface 10 cm of a transitional red earth at Yanco, N.S.W., and of a grey soil of heavy texture at Trangie, N.S.W. Measurements were made in Autumn (May), prior to planting crops of winter oats, at the time of harvest (October) and in December, using both cropped and continuously fallowed soils. At Trangie, additional measurements were made in September, near the beginning of rapid growth in spring. Despite differences in soil type, pH .and location, both sites showed: (i) S15N in extractable mineral nitrogen varied with time (decreasing from 18.7 to 6.0% in fallowed soil at Yanco, and increasing from 5.8 to 12.0%~ under oats at Trangie), and in cropped versus fallowed treatments (12.0 and 5.3% respectively in December at Trangie), and values were different from those of the total soil nitrogen, in which S15N remained virtually unchanged (over all times and sites, S15N = 8.2 � 0.2 at Trangie); (ii) after removal of the crop, S15N in increments of extractable mineral nitrogen were higher than in the total nitrogen of previously cropped soils, whilst in the continuously fallowed soils, S15N of extractable mineral nitrogen was lower than in the total nitrogen. In addition, at Trangie, S15N in the extractable mineral nitrogen was highest late in growth of the oat crop, and this was reflected in the values for S15N of nitrogen assimilated in the crop. Values of the S15N of plant nitrogen agreed well with the S15N of extractable mineral N when the former were determined in increments of plant N during fixed periods of growth and plotted appropriately (the mid-point between sampling times) in relation to the time courses of changes in the mineral N. These results are discussed in relation to the use of 15N natural abundance techniques for estimating nitrogen fixation by nodulated legumes and in the study of other aspects of soil nitrogen cycle processes.
The effect of supplements of rumen-degradable protein and formaldehyde-treated casein on the intake of low-nitrogen roughages by Bos taurus and Bos indicus steers at different stages of maturity
Authors: Hunter RA , Siebert BD
Published: November 2004

The response in voluntary feed intake, firstly to supplements of rumen-degradable protein and then to additional supplements of formaldehyde-treated casein (FTC) was studied in Aberdeen Angus (Bos taurus) and Brahman (Bos indicus) steers fed long-chopped spear grass (Heteropogon contortus) and pangola grass (Digitaria decumbens). The intake responses were measured at four stages of maturity of the steers ranging from soon after weaning to near maturity. On diets deficient in nitrogen the magnitude of the intake response to rumen-degradable protein was greater in Angus than in Brahmans. With the exception of the Angus steers fed spear grass soon after weaning, there was no significant response to FTC with either diet beyond that achieved with rumen-degradable protein. From published values of the digestible protein supplied by the diets and the protein requirements of cattle for maintenance, it was calculated that pangola grass, prior to supplementation with FTC, supplied sufficient digestible protein for maintenance. On the other hand, that supplied by spear grass, prior to supplementation with FTC, was substantially below that required for maintenance. These experimental and calculated data are discussed in terms of factors limiting feed intake, and conclusions drawn about protein requirements for the expression of maximum feed intake of roughage diets.
Effects of severity and repetition of water stress on seed production of Macroptilium atropurpureum cv. Siratro
Authors: Kowithayakorn L , Humphreys LR
Published: November 2004

Macroptilium atropurpureum cv. Siratro was grown in large soil beds in a glasshouse with a water table at constant height below. Water stresses of dawn leaf water potential of - 1.0 MPa (medium stress) or of - 1.5 MPa (severe stress) were developed over 14 or 28 days, either singly or repeated after 42 days of rewatering. These stresses caused some death of terminal shoots and abscission of old leaves, but rapid rates of leaf differentiation restored leaf density to the levels of the control plants upon rewatering. A subsidiary experiment showed lower levels of leaf water potential in young leaves near the apex than in leaves subtending inflorescences.Persistent increases in the rate of floral bud appearance occurred upon rewatering, but the ratio of floral buds surviving to form an inflorescence with flowers was reduced both during and after the imposition of stress. A single cycle of medium stress increased seed yield 36% relative to the control plants, due to increased inflorescence and flower density. Repetition of water stress after 42 days was disadvantageous, and the effects of longer intervals between stress merit investigation. Severe stress of - 1.5 MPa was not beneficial to seed production.
Shading behaviour of sheep: preliminary studies of its relation to thermoregulation, feed and water intakes, and metabolic rates
Authors: Johnson KG
Published: November 2004

Two flocks of Merino ewes, containing 46 and 49 animals respectively, were observed for 6 days during summer while they grazed on irrigated pasture that was partly shaded.Approximately 20% of the animals stayed longer in the sun than the animals that used shade most. From the second flock, five animals of the shading (SH) group were compared in laboratory trials with five non-shading (non-SH) animals. During heat exposure to air temperatures rising from 20 to 50�C over 3 h, non-SH sheep had significantly higher rectal temperatures and lower respiratory rates, suggesting that they were more thermolabile. SH sheep did not respond differently to non-SH sheep to being fed at 50�C instead of 20�C, although SH sheep ate significantly more food (24%) and drank significantly more water (33%) at both temperatures. In a further trial of individual feed and water intakes at 20�C, differences in consumption were again recorded, but were not statistically significant. No significant difference in oxygen consumption between SH and non-SH animals was measured at 20�C.The correlation between shading preferences and thermoregulation in these two flocks indicates that individual sheep may differ in their patterns of thermal adaptation when shading is optional. A possible relation between shading preference and food and water requirements suggests that shading patterns of sheep may also be associated with differences in nutritional adaptation.
The effect of lysine and maize oil in growing and laying diets on the laying performance of crossbred pullets
Authors: Karunajeewa H , Tham SH
Published: November 2004

In a 3 x 3 x 3 factorial experiment, the laying performance of White Leghorn x Australorp pullets, given growing diets (8-20 weeks of age) with the factorial combinations of three levels (4.5, 5.0 and 5.5 g/kg) of lysine and three levels (0, 10 and 20 g/kg) of maize oil and laying diets with 0, 10 and 20 g/kg and 0, 15 and 25 g/kg maize oil from 20 to 52 and 52 to 60 weeks of age, respectively, was measured.In the growing phase, neither the lysine nor maize oil levels in the diet had a significant effect on growth performance. The level of lysine in the growing diet had no effect on subsequent laying performance. There were significant interactions between the levels of maize oil in the growing and laying diets on rate of lay, egg output and feed conversion efficiency. The inclusion of 20g/kg maize oil in the laying diet increased egg weight. None of the dietary treatments had a significant effect on the weights of egg components (yolk, albumen and shell).With increasing level of maize oil in the laying diet, the concentration of myristic, palmitoleic, oleic and linolenic acids in the egg yolk decreased and that of stearic, linoleic and arachidonic acids increased.
The nutritional value for meat chickens of water-damaged wheat from temporary bulk stores in Queensland
Authors: Mannion PF , Blaney BJ , Levitt MS
Published: November 2004

The nutritional value of water-damaged wheat and free-flowing wheat from temporary bulk stores at Goondiwindi was determined. Each was fed to meat chickens as the sole grain component or combined in several proportions, and compared with a control wheat in diets of similar nutrient composition. In addition, the nutrient composition of water-damaged and free-flowing wheat from temporary stores at Meeandarra, Thallon, Jandowae and Millmerran in southern Queensland was determined.A progressive reduction in the ratio of total amino acids to crude protein (0.98-0-70 w/w) and innitrogen-free extract (789-685 g kg-1 dry matter) was associated with increasing severity of water damage. Ether extract and gross energy contents of the dry matter were low in water-damaged wheat from all sites, but only the wheat with the most damage had a lower metabolizable energy content (12.99 versus 14.12 MJ kg-1) in the dry matter and as a proportion of gross energy (71% versus 76%) than free-flowing wheat from the same site.The three diets containing high levels of rotten (two diets) and severely water-damaged wheat (one diet) resulted in an average liveweight gain (26.1 g day-1) and feed conversion (1.86) which was poorer than that of the free-flowing wheat (28.1 g day-1, 1.59) and the average of other less water-damaged wheat treatments (29.7 g day-1, 1.57). The higher average liveweight gain of the latter treatments relative to the free-flowing wheat and control (27.3 g day-1) treatments was significant but was not reflected in better feed conversion. Possible reasons for these findings are discussed.
Relationship between net blotch (Drechslera teres) and losses in grain yield of barley in Western Australia
Authors: Khan TN
Published: November 2004

Losses in the yield of cv. Dampier due to net blotch (Drechslera teres (Sacc.) Shoem.) were examined in six environments in Western Australia. Based on comparison between least diseased and most diseased treatments, there was an overall yield reduction of 21% (P < 0.05). Three models (Critical Point, Area Under Curve and Multiple Point) were used to study the relationship between net blotch infection and percentage yield loss. All models gave similar results. Because of its simplicity, the Critical Point Model based on mean net blotch infection on the top three leaves at GS 75 was chosen. The percentage yield loss in cv. Dampier was defined to be 37% of the mean diseased area on leaves 1 (flag), 2 and 3 at GS 75. This relationship is very similar to that developed earlier for scald, and a common equation for both scald and net blotch was suggested.
Selection of early maturing barley with improved response to drought stress
Authors: Omara MK
Published: November 2004

Selection for early maturing genotypes of barley with improved response to drought was practised among 303 F3 families derived from 11 crosses between five early and two late cultivars of highly diverse origins. Forty-one out of 152 uniformly early F3 lines were selected according to the mean performance and the regression stability index for number of ears/plant over a series of six drought-stressed and non-stressed environments established in clay and sandy soils. The performance of the 41 F4 selections and the five early parents was assessed under a short growing season of drought-stressed sandy soil treatments where plants were subjected to a 20-day dry period at different stages of plant age.Heritability for number of ears/plant estimated from parent-offspring regressions \vas higher under the favourable treatment of the clay soil (0.31) than under the stressed sandy soil treatments (0.15) A selection advance of 25.2% was manifested only under the favourable treatment of the clay soil. A correlated response to selection was also detected in grain yield/plant which amounted to 24.4% of the parental mean under the favourable treatment only. This was attributed to the strong association between number of ears/plant and grain yield/plant observed under the favourable condition which was rather weak under drought. Therefore, number of ears/plant in not a satisfactory selection criterion for developing betteryielding cultivars for moisture-stressed sandy soils. The expected genetic advance by selecting among F4 lines for grain yield/plant under drought is greater (28.7%) than that based on number of ears/plant (15.15%).The response of the early selections to drought stressed sandy soil treatments was characterized by a 10 days' reduction in time to flowering and a corresponding prolongation in time from flowering to maturity. Moreover, the early selections which recovered from a drought period imposed later than the seedling-jointing stage reached maturity earlier, but with significant increases in number of ears/plant and grain yield/plant than the control.
Nitrogen metabolism and plasma urea concentrations in fleeceweight-selected and control Romney rams
Authors: McCutcheon SN , Mackenzie DDS , Blair HT
Published: November 2004

Nitrogen retention and plasma urea concentrations were examined in 2-year-old Romney rams from fleeceweight-selection and control lines. In four experimental periods rams were fed chaffed lucerne hay (110% of maintenance energy requirements) three times daily (Period I), twelve times daily (Period II), twice daily (Period IV), or were fasted (Period 111). Nitrogen balance was measured in Period I, while plasma concentrations, urinary excretions and clearances of urea and creatinine were examined in Periods II-IV. Water intake and urine output were measured in all periods. Plasma urea concentrations were also measured in the same rams at grazing. Differences between the lines in water intake, urine output, faecal and urinary nitrogen excretion and nitrogen retention were not significant. Control rams maintained significantly higher plasma concentrations of urea and creatinine than fleeceweight-selected rams but only under controlled feeding conditions (particularly twelve times daily feeding). Differences between the lines in plasma urea concentration could be accounted for by the (non-significantly) greater urinary urea excretion, and lower creatinine clearance rate, of control rams. Measurement of plasma urea concentration in sheep may provide a useful predictor of genetic merit for fleeceweight. However, it will be necessary to measure plasma urea concentration under controlled feeding conditions to accurately rank animals. Concurrent measurement of creatinine clearance rate and urinary urea excretion should also enhance the accuracy of prediction of genetic merit.
Yield components and nitrogen partitioning of maize in response to nitrogen before and after anthesis
Authors: Pearson CJ , Jacobs BC
Published: November 2004

Zea mays hybrid XL66 was grown with irrigation in sand in the field and subjected to different rates of nitrogen supply from floral initiation to anthesis and again from anthesis to maturity. Nitrogen supply during spikelet differentiation affected grain number markedly. Nitrogen supply during grain filling had a small but significant effect on the rate of grain filling and an effect on the rate of nitrogen entry to the grain, causing a 1.3-fold change in percentage grain nitrogen. Increasing the nitrogen supply produced larger plants, but the distribution of nitrogen and dry weight among plant parts were similar and the harvest indices for dry weight (0.46) and nitrogen (0.66) were the same over all nitrogen treatments. We found no evidence that shoot size per se controlled grain number or rate of grain growth; rather, fertilizer management during spikelet differentiation had most effect on yield of XL66.
Comparative tolerance of sugarcane, navybean, soybean and maize to aluminium toxicity
Authors: Hetherington SJ , Asher CJ , Blamey FPC
Published: November 2004

The aluminium (Al) tolerance of three sugarcane (Saccharum spp.) cultivars was compared with one cultivar each of navybean (Phaseolus vulgaris), soybean (Glycine max), and maize (Zea mays) in a short-term solution culture experiment. The experiment was conducted under closely controlled conditions of pH (adjusted daily to 4.2 � 0.02) and root temperature (28�C) over a wide range of Al levels expressed as the sum of activities of monomeric A1 species (mean +aAL mono 0, 4, 14, 54, and 222 8M). The three sugarcane cultivars, Q77, Q113 and Q117, were found to be considerably more tolerant of Al in solution than were the other three species. At 14 8M +aAL mono toxicity symptoms on the sugarcane roots were slight, but were well developed on the roots of the other three species. At 220 8M +aAL mono the distance from the root tip to the first visible lateral was reduced by 9-30% in the sugarcane cultivars compared with 79% in maize and navybean, and 91% in soybean. Interpolation of curves fitted to root length data indicated critical (i.e. 10% total root length reduction) +aAL mono of 11-21 8M for the sugarcane cultivars compared with 2.0 8M, 1.8 8M, and 1.0 8M for soybean, maize, and navybean, respectively. Implications for the management of sugarcane tand are discussed briefly.
The effect of stocking rate on the population dynamics of siratro in siratro (Macroptilium atropurpureum)-setaria (Setaria sphacelata) pastures in south-east Queensland. II. Seed set, soil seed reserves, seedling recruitment and seedling survival
Authors: Jones RM , Bunch GA
Published: November 2004

Measurements were made of the seed set, seed content in cattle faeces, soil seed reserves, seedling regeneration and seedling survival of Siratro (Macroptilurn atropurpureum) in south-east Queensland. Measurements were made from 1972 to 1985 in pastures of Siratro/setaria (Setaria sphacelata) sown in 1968 and stocked at 1.1, 1.7 and 2.3 and at 3.0 (1969-1973) reduced to 2.0 (1974-1985) heifers ha-1. Siratro seed set and seedling demography were markedly affected by stocking rate. At the highest stocking rate, Siratro yields were low and seed input ceased after 1972, yet appreciable seedling recruitment from the soil seed bank was maintained for a further 10 years. At the lightest stocking rate (1.1 heifers ha-1), seed set and soil seed reserves were highest, but seedling recruitment was of little importance as almost all seedlings died. Seedling recruitment and survival were best at an intermediate stocking rate (1.7 heifers ha-1), where they were the key to long-term persistence of Siratro. Soil seed reserves of Siratro ranged from 500 m-2 under light stocking to < 100 m-2 after several years of heavy stocking. Very little seed was recovered in cattle faeces. Likely factors responsible for seedling death (light, water, nutrients, grazing, frosting and insect damage) are discussed. The limitations of seed set and seedling regeneration in the persistence of Siratro are contrasted with some other perennial pasture legumes. Studies of this type can help in qualitatively predicting long-term persistence of pasture legumes under different conditions of management and climate.
The identity of barley yellow dwarf virus isolates in cereals and grasses from mainland Australia
Authors: Sward RJ , Lister RM
Published: November 2004

Four serologically distinct types of barley yellow dwarf virus (BYDV) were identified infecting cereals and grasses collected around mainland Australia. On the basis of serological relatedness to North American type-isolateq, the Australian isolates were classified as MAV-, PAV-, RMV- and RPV-like. However, aphid transmission studies showed that, while the Australian PAV-, RPV-, and RMV-like isolates had conventional vector relationships, the Australian MAV-like isolates had Rhopaloszphium padi as a major vector species. Differences in the Sitobion species occurring in North America and Australia made comparisons of the transmissibility of MAV- and PAV-like isolates by these vectors impractical. Isolates serologically like PAV were by far the most common viruses in each State surveyed, with the next most common varying from State to State. The identifications of RMV- and MAV-like isolates are the first confirmed records of these types of BYDV in Australia.
Dynamics of pasture invasion by three weeds, Avena fatua L., Carduus tenuiflorus Curt. and Onopordum acanthium L
Authors: Auld BA
Published: November 2004

Three weeds, Avena fatua L., Carduus tenuiflorus Curt. and Onopordum acanthium L., were deliberately introduced to two 1 ha fields in which they had not been recorded previously. One field was mown annually after weed seed fall, the other was grazed by sheep in late summer-autumn. The population growth and spread of flowering individuals of each species from sites of 10 original mother plants in each field was recorded for two years of spread. The location of daughter plants was described using a single parameter from fitted curves.Grazing compared with mowing had no significant effect on population growth, dispersal or area occupied for any species. C. tenuiforus populations had greater dispersing fractions than the other species, and this appeared to be influenced by wind. This species also had a greater initial population growth and spread than the other species. In the second year, the population of C. tenuiflorus declined in grazed and ungrazed treatments, which was attributed to its population's tendency to establish each year from a single cohort. Although the population size and dispersal gradients of A. fatua and O. acanthium were similar after two years of spread for each species, O. acanthium occupied a greater area owing to a higher frequency of low density patches. Spread rates for O. acanthium, A. fatua and C. tenuifloms respectively, increased, remained constant and decreased with time.
Factors limiting the intake of feed by sheep. 13. Voluntary roughage consumption in late pregnancy and early lactation in relation to protein nutrition
Authors: Weston RH
Published: November 2004

Studies were made of (i) the effect of protein nutrition on voluntary roughage consumption in late pregnancy and early lactation, and (ii) the effect of pregnancy on the voluntary consumption of a high protein ground mixture of roughages and concentrates. The three roughage diets used were based on wheaten hay, a mixture of wheaten and lucerne hays and wheaten straw. In late pregnancy, voluntary consumption varied with roughage quality being highest with the wheaten hay diet and lowest with the straw diet. The provision of protein supplements decreased the consumption of wheaten hay diet (-6%), increased the consumption of mixed hay diet during days 31-18 pre-partum (+ 5%), but not at other times, and increased straw diet consumption (+ 17%). The intake of the high protein ground diet was not affected by pregnancy until about day 21 pre-partum, after which it declined at c. 0.9% per day. In early lactation, protein supplement decreased the consumption of wheaten hay diet (-6%), but had no effect on the consumption of mixed hay diet. It was concluded that (i) roughages of comparatively low protein value may provide adequate protein for the expression of maximum voluntary roughage consumption in late pregnancy and early lactation, (ii) feed intake regulation in late pregnancy could not be based solely on physical limitations, on energy metabolism considerations or on hormonal responses, and (iii) changes in the metabolism of maternal adipose tissue in late pregnancy could play a role in the intake regulation.
Epidemiology of nematode infections of weaner sheep in the cereal zone of South Australia
Authors: Pullman AL , Beveridge I , Martin RR
Published: November 2004

Trichostrongyloid nematode infections of weaner sheep were investigated at the Turretfield and Minnipa Research Centres in the cereal zone of South Australia over a three-year period (1982-1985). Acquisition of nematode larvae from pasture occurred over a limited period each year, principally during the winter months, and coincided with the elimination of, or a reduction in the numbers of adult nematodes; sheep subsequently resisted challenge by infective larvae. Faecal egg counts were elevated during the summer, but declined to negligible levels during the winter months when larval challenge was at its maximum. Scouring, which was common in untreated sheep during winter at Turretfield, did not occur in regularly treated sheep, but no adverse effects were noted at Minnipa.