bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of available soil N and rates of inoculation on nitrogen fixation by irrigated soybeans and evaluation of δ15N methods for measurement
Authors: Bergersen FJ , Brockwell J , Gault RR , Morthorpe L , Peoples MB , Turner GL
Published: November 2004

Nitrogen fixation by irrigated soybeans (Glycine max (L.) Merr. cv. Forrest) was studied in a field experiment on a grey clay soil at Trangie, N.S.W. during the summer of 1985-86. Cropping with oats during the previous winter diminished the concentration of plant-available nitrogen in the soil from 37.6 to 18.5 mg N kg-1 and induced differences in the natural abundance of 15N (S15N) in this nitrogen. Four rates of liquid inoculation with Bradyrhizobium japonicum strain CB 1809, interacted with soil nitrogen to produce a wide range of nodulation of the soybeans. The following main effects on growth and N2 fixation resulted: (a) Initially, growth and accumulation of plant nitrogen was lower in pre-cropped than in prefallowed soil but N2 fixation was higher. (b) Nitrogen fixation during seed development was high in pre-cropped soil and greatest at the highest rate of inoculation. It resulted in high yields of seed (3.5 t ha-1 with 100 times the normal inoculation) with significantly higher concentration of seed nitrogen than from plants grown in prefallowed soil. (c) With increasing rates of inoculation on the pre-fallowed soil, more uniform nodulation was associated with smaller variances in most of the parameters studied. Other findings included further validation of the S15N method of calculating the proportion (p) of plant nitrogen derived from N2 fixation, with good agreement between treatment effects based on such estimates and those based on the relative concentrations of ureides in vacuum-extracted xylem sap. The values of p from S15N measurements on shoot nitrogen were affected little by inclusion of root nitrogen, and similar values were obtained when uninoculated, unnodulated Forrest soybeans, a nonnodulating genotype (non-nod Clark 63) or extractable mineral nitrogen of soil were used to estimate the S15N of plant N assimilated from soil. More dry matter (flowers, young pods and older leaves) containing more nitrogen (23-26 kg N ha-1) fell from the canopy of plants during seed maturation on pre-fallowed soil (high nitrogen) than on pre-cropped soil (13-15 kg N ha-1). Several correlations between the various quantities measured were noted and are discussed. It is concluded that growing winter cereals on land newly broken from pasture, coupled with high rates of inoculation of the following soybeans, may be a profitable way of diminishing plant-available soil nitrogen, thus maximizing the contribution of nitrogen from N2 fixation with benefits in seed yield and protein content.
Selenium concentration in the blood of ruminants grazing in northern New South Wales. 3. Relationship between blood concentration and the response in liveweight of grazing cattle given a selenium supplement
Authors: Langlands JP , Donald GE , Bowles JE , Smith AJ
Published: November 2004

Approximately 700 yearling (Experiment 1) or unweaned (Experiment 2) cattle grazed commercial farms on the New England Tablelands of New South Wales, and were supplemented or not supplemented with selenium (Se). Whole blood and plasma Se concentrations, and liveweight gains were measured over periods of 3-7 months. In a third experiment, 96 castrated male weaned calves on a farm with a long history of unthriftiness were allocated to four groups, and were supplemented with either Se or copper in a factorial design.In Experiments 1 and 2, mean whole blood and plasma Se concentrations of unsupplemented animals on individual farms ranged from 0.004 to 0.139, and from 0.002 to 0.058 8g Se/ml respectively, but growth rates of only two of the twenty herds responded significantly to Se supplementation, and both showed diarrhoea and ill thrift at the start of the experiment. The herd in Experiment 3 also showed ill thrift, and growth rate responded to supplementation with Se, but copper depressed growth. Se concentrations in blood and plasma were generally poor indicators of responsiveness. Possible reasons are suggested.
Cattle handling at abattoirs. 3. The effects of feeding, and of different feeds, during the resting period before slaughter on liveweight carcasses and muscle properties
Authors: Wythes JR , Round PJ , Johnston GN , Smith PC
Published: November 2004

The effects of feeding lucerne hay or rice straw during the resting period before slaughter on live, carcass and liver weights, bruising, the percentages of condemned head and tongues and of rumens with ingesta spillage, and muscle properties of cattle were examined. The 217 British breed and 70 Brahman steers (mean liveweights of 582 and 603 kg) had been grazing native pastures in northern Queensland. They were transported 440 km by road to an abattoir.The seven groups (each 41 steers) had access to water from unloading at the abattoir (late day 2) until slaughter. Three groups (N2, N4 and N6) were not fed, while two groups were fed ad libitum rice straw (RS4 and RS6) and another two groups were fed ad libitum lucerne hay (LH4 and LH6) from day 3 until 24 h before slaughter. The period from mustering to slaughter was 2 days for group N2,4 days for groups N4, RS4 and LH4, and 6 days for N6, RS6 and LH6.Unfed steers lost 4.7% of their pre-transport liveweight after 3 days and 9.1% after 5 days, while the fed steers lost 34% and 6.7%, respectively.Group N2 had a heavier (P<O.05) mean carcass weight than groups N4, RS4, RS6 and LH6 (351 kg compared with 343-344 kg). Both N2 and LH4 (348 kg) were heavier (P< 0.05) than group N6 (340 kg). Trends in mean dressing percentage were the same as for carcass weight. Group N2 had a heavier (P< 0.05) mean liver weight than all other groups, with no effect of feeding treatment. Group N2 and the fed groups (except RS6) had a greater (P< 0.05) mean water content for the M. longus colli than groups N4 and N6.Treatment had no significant effect on mean bruise score, fat thickness, mean pH value of M. longissirnus dorsi 24 h post mortem, the percentage of carcasses with high (>6.00) pH values, and the percentages of heads and tongue condemned due to ingesta contamination and rumens contaminated with ingesta spillage.
Contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) Moench under water-limited conditions. II. Water stress after anthesis
Authors: Ludlow MM , Santamaria JM , Fukai S
Published: November 2004

The contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) subjected to water stress between anthesis and maturity was studied using six entries. Three of the entries (Goldrush, E57, and DK470) were selected for high osmotic adjustment and the other three (Texas 610SR, Texas 671, and SC 219-9-19-1) for low osmotic adjustment, and divided into early, intermediate and late maturity groups. Entries were either well watered, or subjected to a 50-day period of water shortage after anthesis following being well-watered prior to anthesis. Entries selected for high osmotic adjustment had mean values of osmotic adjustment at the end of the post-anthesis stress more than double those selected for low osmotic adjustment. The corresponding mean grain yield of entries with high osmotic adjustment were 24% higher than that of entries with low osmotic adjustment. The higher yield was due to both more and larger grains, and it was associated with higher harvest index and distribution index. At best, the difference in dry matter at maturity could explain only a few per cent of the difference in grain yield between entries with low and high osmotic adjustment. Water stress prior to anthesis (previous paper) reduced yield more than a post-anthesis stress of the same intensity. However, osmotic adjustment was equally effective in minimizing the reduction in grain yields in both stages. The use of osmotic adjustment as a selection trait in programs to improve the yield of grain sorghum is briefly discussed.
Variable paths to seed production within the Kangaroo Valley cultivar of Lolium perenne
Authors: Shah SG , Pearson CJ , Kirby AC
Published: November 2004

Components of seed yield were measured in an erect, early-flowering biotype and a prostrate, late-flowering biotype of Lolium perenne cv. Kangaroo Valley at temperatures from 15/10 to 24/19�C (12/12 h day/night). We aimed to determine if each biotype had distinctive components of seed yield, and if these varied according to temperature. The two biotypes had distinctive paths to seed yield. Seed yield per plant in an erect biotype depended more on seed weight per spike and less on spike number than in a prostrate biotype. The distinctive paths to seed yield, and relative stability in paths across temperatures, indicated that it was possible to select genotypes from within the Kangaroo Valley cultivar which had particular correlations among components of yield. Floral development was accelerated, but seed yield per plant and most of its components were reduced, at high temperature; only the mean daily rate of dry weight accumulation by individual seeds was the same at all temperatures. At any temperature, seed weight per spike declined almost linearly with lateness of spike emergence within a plant: spikes which emerged within 21 days of the earliest spike contributed 80% of the seed yield per plant. We conclude that biotypes can be selected within the Kangaroo Valley cultivar to have distinctive components of seed yield and, based on the two biotypes we studied, commercial seed production should be based at a location having relatively low temperatures.
A review of factors affecting minimum temperature reached on clear, windless nights.
Authors: Gardner WK , McDonald GK , Ellis SE , Platt M , Flood RG
Published: November 2004

A mathematical model of heat flux in which net flux was assumed to be proportional to the surface temperature was used to examine the effects of important environmental variables on minimum surface temperatures reached during cloudless nights. Variables considered were altitude, atmospheric water content, surface emissivity, soil heat capacity and conductivity, length of night, and initial starting temperature. Final temperatures reached were especially sensitive to changes in soil thermal conductivity and heat capacity. Both these parameters are affected by moisture content (particularly when low), making this the single most important factor affecting the severity of frost. Lower initial starting temperatures and longer nights increase the severity of frosting, as does any decrease in the depth of the atmosphere (as happens with changes in altitude) or reductions in the water content of the atmosphere. Emissivity of the radiating surface is relatively unimportant. Temperature profiles in the soil were similar, but extended to greater depths as heat capacitance declined, whereas lower thermal conductivity resulted in cooler surface temperatures while the decline in temperature did not extend as deep. The model was shown to be an improvement on one in which net flux was assumed to remain constant, and allows for a more instructive sensitivity analysis.
Exercise in Merino sheep dash the relationships between work intensity, endurance, anaerobic threshold and glucose metabolism
Authors: Pethick DW , Miller CB , Harman NG
Published: November 2004

The effect of exercise intensity on (i) the ability of sheep to sustain exercise and (ii) glucose metabolism was investigated in fed non-pregnant adult Merino ewes. Five animals were prepared with cannulae to study the splanchnic tissues using the arteriovenous difference technique either at rest or during 8 levels of exercise: 3, 5, 7 and 9 km h-1 at either 0� or 9� incline. The anaerobic threshold, determined by elevation of blood lactate concentration or lactate/pyruvate ratio, occurred at a work rate of about 6-10 watts/kg body wt (7 km h-1 on 0� incline, 3 km h-1 on 9� incline). Only exercise well in excess of the anaerobic threshold resulted in ewes showing fatigue. Fatigue was not associated with carbohydrate depletion or lacticacidosis. Changes in the partial pressure of CO2 and the pH of blood indicated a marked respiratory alkalosis that was related to the severity of exercise, suggesting that thermoregulation may have been an important component of fatigue. Splanchnic blood flow declined when the intensity of exercise exceeded the anaerobic threshold; however, this did not compromise splanchnic function as assessed by oxygen and metabolite uptake. During exercise below the anaerobic threshold euglycemia was maintained while a pronounced hyperglycemia, that became more severe as the work rate increased, was found for exercise above the anaerobic threshold. The release of glucose by the liver increased significantly at all work rates and markedly so after the anaerobic threshold, such that the resultant hyperglycemia was consistent with an exaggerated hepatic glucose release due to 'feed forward' control. The contribution of lactate and glycerol to gluconeogenesis, assuming complete conversion, remained constant at 18-25% except at the highest work load where the contribution significantly declined to 9%. The decline was due to (i) saturation of hepatic lactate uptake and (ii) a failure for glycerol concentration and so uptake to increase beyond a work rate of 22 W kg-1. The requirement for gluconeogenic end products of digestion for animals grazed under extensive conditions would be 9-30% greater than for animals not exercising, depending upon the speed and inclination of exercise.
A soil test for aluminium toxicity in acidic subsoils of yellow earths in Western Australia
Authors: Carr SJ , Ritchie GSP , Porter WM
Published: November 2004

Many of the yellow earths in the Western Australian wheatbelt have naturally acidic subsoils which can reduce the yield of wheat grown on them. Current methods of assessing soil acidity cannot identify which soils have subsoil acidity severe enough to restrict wheat yields. We conducted 53 field experiments at 34 sites in 5 regions over 3 years to determine the relationship between yield of wheat and several different indices for identifying subsoils with toxic concentrations of aluminium, Al. Initially, we identified that the concentration of aluminium, [All, in the soil solution and in 1 : 5 0.005 M KCl extracts of soil from the 15-25 cm layer was responsible for the majority of the decrease in wheat yield. The concentration of Al in a 1 : 5 0.005 M KCl extract in the 15-25 cm layer was well correlated with grain yield of wheat grown on yellow earth soils in the Merredin region, provided the soils had similar fertilizer treatments. The ratio [All : [Na] in a 1 : 5 0.005 M KCl extract was a better predictor than [All alone of grain yield of wheat grown on yellow earths in different regions and with different fertilizer practices. The three seasons had little effect on the correlation between yield and different soil indices. The correlations determined were strongly affected by regional differences, which were probably due to differing water supply and availability. The choice of toxicity index depended on the uniformity of fertilizer management practices within a region and it appeared that both ionic strength and calcium were important mitigating factors.
Propagation of yellow bells (Geleznowia verrucosa Turcz., Rutaceae) from seed
Authors: Paynter BH , Dixon KW
Published: November 2004

Geleznowia verrucosa Turcz. (Rutaceae) is a commercially important, bush-picked wildflower that has no known commercial means of propagation. This study examined factors influencing seed dormancy and likely to restrict germination of the species. Germination of entire, untreated seed was low (less than 2%), but removal of a small portion of the testa at or near the radicle end of the seed improved germination. This response was affected by the temperature under which the seed germinated, but was unaffected by exposure of the seed to light while germinating. The percentage germination of nicked seeds 52 days after sowing increased from 8% to 16-19% by increasing the temperature from 15/10�C to 20/15�C; 55-60% of nicked seed germinated when the germination temperature was increased to 23/15�C. The germination of nicked seed was reduced by leaching in running tap water. Following 1 week of leaching the germination percentage of nicked seed at day 52 in the glasshouse was reduced from 16% to 9%, with a further decrease to 5% after 2 weeks of leaching. There was also no stimulatory effect on the germination of entire seeds by stratifying the seed at 5�C after periods of solarisation. It is concluded that dormancy of fresh seeds of G. verrucosa is caused, in part, by the mechanical restriction of the testa on embryo growth and elongation.
Flood irrigation of wheat on a transitional red-brown earth. I. Effect of duration of ponding on soil water, plant growth, yield and N uptake
Authors: Melhuish FM , Humphreys E , Muirhead WA , White RJG
Published: November 2004

Long periods of waterlogging during irrigation are thought to adversely affect wheat growth and yield. This work quantifies these effects for wheat (Triticum aestivum L. cv. Bindawarra) growing on a transitional red-brown earth. The crop was irrigated on four occasions during spring. At each irrigation six ponding treatments were imposed involving sprinkler irrigation (SP) or flooding for 1, 12, 24, 48 or 96 h. Each plot always received the same treatment. Nitrogen fertilizer was applied at sowing (23 kg N ha-1 as ammonium phosphates) and at the end of tillering, 3 weeks before the first irrigation (100 kg N ha-1 as urea). There was also a 1 h ponding treatment which did not receive urea at the end of tillering. Grain yield on the 48 h and 96 h ponding treatments was significantly lower than on SP, 1 h and 12 h. Yield declined by 69 kg ha-1 for each day that water was ponded on the surface, or by 55 kg ha-1 for each day that the estimated soil water depletion was below 25 mm. The wheat crop suffered stress due to lack of aeration for periods varying from 42% (1 h and SP) to 68% (96 h) of the time interval between early stem elongation and physiological maturity. The grain yield and N uptake data indicate that the site was highly responsive to N fertilizer. However, there was no significant effect of ponding treatment on total N uptake, suggesting that the yield differences between the ponding treatments were not caused by differences in N availability. The results demonstrate that yield loss through waterlogging can be minimized by changing to irrigation management practices that minimise the period of ponding.
Assessment of yield loss caused by common root rot in wheat cultivars in Queensland
Authors: Wildermuth GB , Tinline RD , McNamara RB
Published: November 2004

The effects of common root rot (CRR) caused by Bipolaris sorokiniana on grain yield, number of tillers, number of grains and grain weight of wheat plants were determined in four field experiments. Sites with different soil populations of B. sorokiniana were selected and inoculum of the fungus added to some plots. Disease and yield measurements were made on eight cultivars and lines differing in susceptibility to CRR. Timgalen, Songlen and Hartog were susceptible whereas Kite, 1008 C16, 141-4 and ISWYN 32 were partially resistant to CRR. Grain yield, tiller and grain number, but not grain weight decreased as disease severity increased. Diseased plants had lower tiller numbers than healthy ones and as a consequence a reduced number of grains and grain yield per plant. Five methods were compared for estimating yield loss caused by the disease. Polynomial regression equations for each cultivar between yield and disease rating of sub-crown internodes or multiple regression equations between yield and disease parameters of sub-crown internodes or tiller bases were established. A third method involved the projection of yield losses from one cultivar to other cultivars and in a fourth method yield losses were estimated from actual yields. In addition, an equation Yield loss (%) = 3 46 + 0.23 disease severity) (%) was established in one experiment and used as a fifth method in the other experiments. Yield losses estimated by methods 1 and 2 were similar and higher than those from the other methods. In areas where disease severity is high, methods 1 and 5 appear to be the most suitable for determining yield losses. Losses in a susceptible cultivar, Timgalen, varied between 13.9 and 23.9% whereas those in a partially resistant cultivar, 1008 C16, varied between 6.8 and 13.6%.
Effect of molasses, sodium bentonite and zeolite on urea toxicity
Authors: Stephenson RGA , Huff JL , Krebs G , Howitt CJ
Published: November 2004

Molasses, sodium bentonite (montmorillonite clay) and zeolite (crushed clinoptilolite rock) were examined as supplement ingredients to improve the safety margin of urea supplementation in a series of seven experiments. These experiments were designed to provide an understanding of the relationship between urea intake and the influence of the above ingredients on rumen pH and total ammonia concentrations. Rumen fistulated Merino ewes of 35-40 kg liveweight were administered various amounts of urea with and without supplement mixes. Rumen parameters were measured at 0, 0.5, 1-0, 1.5, 2.5, 5.0 and 24 h after treatment administration. Acetic acid and sucrose were also tested together with molasses for comparative effects on rumen parameters. In the last experiment, blood pH and total plasma ammonia were also determined. Free ammonia values of rumen liquor were calculated for experiments 2 to 7. In four experiments, molasses at 50, 100 and/or 150 g mixed with urea significantly reduced the normal rapid rise in ruminal pH, total and free ammonia values compared with urea (10 g) only treatments. In two experiments, associated presence or absence of clinical toxicity at various quantities of urea (8 to 25 g) with and without active ingredients confirmed the postive effect of molasses in preventing toxicity at <0.44 g urea/ kg liveweight. The addition of molasses reduced the increase in ruminal pH by up to 0-5 pH units and absolute values were consistently below pH 7-0. Sucrose (100 g) and acetic acid (800 mL of 1 M ) had the same and greater effect, respectively, compared with molasses (150 g) when added with urea (10 g) on ruminal pH and total and free ammonia changes over five hours post treatment. The partly hydrated urea / bentonite mix (approx 1 : 1 bentonite : water ratio) was associated with a delay in the increases in ruminal pH and free ammonia concentrations. Bentonite mixes, in either fully hydrated or fully dehydrated states, and zeolite mixes resulted in no significant effects. With reference to previous reports, the results support the positive role of a stable acid pH in the rumen for ensuring safe urea supplementation.
Nitrogen response characteristics of wheat protein in relation to yield responses and their interactions with phosphorus
Authors: Holford ICR , Doyle AD , Leckie CC
Published: November 2004

Wheat fertilizer experiments at 58 sites on the north-western slopes and plains of New South Wales clearly demonstrated a widespread and severe deficiency of nitrogen on many soils. The frequency (70%) and magnitude of responses to nitrogen were much greater than previously recorded. Nitrogen fertilizer required to achieve near-maximum yields was also much greater, with more than half the experiments requiring more than 30 kg N/ha and 23 experiments requiring more than 60 kg/ha. Deficiency of nitrogen for grain protein was almost universal with only two experiments failing to respond to nitrogen fertilizer. The yield response curves for all except three experiments were well fitted by the exponential (Mitscherlich) equation, but the majority of protein response curves were convex to the X axis, or linear, so that maximum protein concentrations could not be estimated. There were four distinct types of protein response curves, and their occurrence seemed to be related to the degree of nitrogen deficiency. Where nitrogen was most deficient (mean protein <10.5%), response curves were convex or linear; at intermediate deficiency (mean protein 11.7%), response curves were sigmoid, and at low deficiency (mean protein 13.4%), curves were exponential. Yield response rarely occurred where grain protein was greater than 12%. In 10 experiments with convex or sigmoid curves, the first increment of fertilizer depressed protein levels, due to the dilution effect of a large yield response. Increasing amounts of phosphorus fertilizer increased the response to nitrogen in nine experiments and in most of these the response curvature was correspondingly decreased, especially at the highest rate of phosphate. These interactions showed that nitrogen was the primary limiting factor in most of these experiments. P fertilizer tended to depress protein concentrations, especially in the absence of N fertilizer, but it had no consistent effect on protein response to N. Because of the dominance of convex protein response curves, much higher levels of fertilizer N were required to give maximum protein responses than were required to give maximum incremental yield responses. It was usually uneconomic therefore to use fertilizer solely to maximize protein increases.
Irrigation management of soybean (Glycine max (L.) Merrill) in a semi-arid tropical environment. I. Effect of irrigation frequency on growth, development and yield
Authors: Garside AL , Lawn RJ , Byth DE
Published: November 2004

The effect of frequency of irrigation on the growth, development and yield of soybeans was studied in two experiments at the Irrigation Research Station, Ord Irrigation Area (15�39'S., 128�43' E.), Western Australia. Irrigation frequencies were based on Class A pan evaporation and involved irrigation after every 30, 60, 120 or 240 mm of cumulative pan evaporation. An additional treatment, saturated soil culture (SSC) or continuous furrow irrigation (analogous to 0 mm pan evaporation), was included in one of the experiments. Seed yields increased linearly with increasing irrigation frequency with the highest yields being obtained with SSC. Increasing the frequency of irrigation increased seed yields through the promotion and prolongation of crop growth. Growth rates of all plant components, viz. vegetative, reproductive, roots and nodules 'were enhanced by more frequent irrigation, senescence was delayed, and leaf area retained later in the growing period. Greater yields were reflected mainly in larger seed. The physiological basis for the observed responses is discussed.
Predominance of flowers and newly formed pods in reproductive abscission of Lupinus angustifolius L
Authors: Pigeaire A , Delane R , Seymor A , Atkins CA
Published: November 2004

The stage of development at which reproductive organs abscised on the main inflorescence of Lupinus angustifolius L. plants was studied in field plot trials which incorporated site, sowing date, density and cultivar treatments. The average number of pods on the main inflorescence at final harvest ranged over 1.8 to 8.4, the Reproductive Index (number of seeds per gram total above-ground dry weight, excluding seeds) varied from 3.1 to 7.6, and the Harvest Index from 0.17 to 0.50. Four stages at which abscission occurred were identified (flower [ovaries 7-8 mm long], pl [pods 9-10 mm], p2 [pods 11-13 mm], p3 [pods 14-27 mm long]) and used to assess reproductive development on a week by week basis. In all treatments, losses of flowers and pl pods accounted for 92% or more of total reproductive abscission and, of this, the majority was due to flower abscission. The number of abscised pl pods was relatively stable across treatments, but the number of p2 and p3 pods which abscised varied markedly with sowing date, possibly indicating a relationship with changes in environmental conditions. Examination of ovaries following cryosectioning and fluorescence microscopy showed that pollination of ovules occurred with a similarly high frequency in flowers destined to abscise (77%) compared with those destined to form pods (88%). The difference was due to a 50% probability of pollination of the fifth ovule in ovaries of flowers forming pods and only a 25% probability in those which abscised. The data are discussed in relation to the likely physiological basis for the regulation of reproductive abscission in the species.
Duration of zinc uptake inhibition by chlorsulfuron in wheat
Authors: Osborne LD , Robson AD
Published: November 2004

The duration of inhibition of zinc uptake by chlorsulfuron was examined in wheat plants in a glasshouse experiment. Chlorsulfuron decreased shoot weight, root weight and zinc uptake. Plants that were treated with chlorsulfuron and adequately supplied with zinc partially recovered from root and shoot growth inhibition by 6 weeks and zinc uptake was recovering by 8 weeks. Plants that were seriously zinc deficient did not recover. In this experiment, potential grain yield was only reduced by chlorsulfuron when zinc supplies were inadequate. It is suggested that the recovery of plants from zinc deficiency may be the result of two processes; hydrolysis of chlorsulfuron with time removing constraints to root growth and functioning, and the release of root exudates from zinc deficient plants effective at mobilizing zinc from soil. In the field, chlorsulfuron is only likely to induce zinc deficiency and reduce yield in wheat where supplies of this trace element are marginal for growth.
Metabolism in sheep of gallic acid, tannic acid and hydrolysable tannin from Terminalia oblongata
Authors: Murdiati TB , McSweeney CS , Lowry JB
Published: November 2004

Hydrolysable tannin (HT) is present in a variety of tropical browse plants, some of which poison ruminants. In an attempt to clarify the toxic action, we investigated the major urinary metabolites resulting from dosing of sheep with the HT, tannic acid; its simplest and major phenolic component, gallic acid; and the HT-containing and toxic Terminalia oblongata. Phenolic metabolites were separated by HPLC and their structures investigated by proton and 13C NMR. Gallic acid was less toxic (w/w) than tannic acid. Comparison of urinary metabolites from rumen and abomasal administration indicated that decarboxylation and reductive dehydroxylation of phenolics occurred principally in the rumen and a significant proportion was totally degraded. Rumen metabolism appeared to prevent toxicity from gallic and tannic acid at dose rates of <0.4 g/kg liveweight per day. Resorcinol glucuronide and the glucuronide of 2-carboxy-2'4'4,6,-tetrahydroxy diphenyl 2, 2'-lactone were the major urinary metabolites derived from tamic acid and probably from yellow-wood HT while resorcinol glucuronide was the major product of gallic acid metabolism. Minor urinary metabolites included unconjugated pyrogallol, resorcinol and phloroglucinol. Toxicity appeared to correlate with the passage of the diphenyl lactone metabolite, presumably arising from the degradation of the hexahydroxydiphenic acid moiety in HT. The current studies indicate that yellow-wood toxicity probably occurs under circumstances when animals ingest leaf containing high levels of HT without prior conditioning. A diagnosis of yellow-wood toxicity could be confirmed by the detection of resorcinol and diphenyl lactone metabolites in urine of affected ruminants.
Effect of forage particle length on rumen digesta load, packing density and voluntary feed intake by sheep
Authors: Gherardi SG , Kellaway RC , Black JL
Published: November 2004

The effect of forage particle length (4 to 101 mm) on packing density of oesophageal extrusa was investigated following ingestion of chopped wheaten hay by sheep. Packing density of oesophageal extrusa from 4 mm hay was greater than that from hay 21 mm and longer; the difference was associated with smaller particle size and a lower modulus of fineness. There was a significant positive correlation between the intake rate of hay by individual sheep and size of extrusa particles for three of the five forage lengths. The effect of packing density of ingested forage on rumen digesta load and voluntary intake was examined subsequently by feeding sheep hay chopped to either 4 or 21 mm lengths. hducing the particle length of hay from 21 to 4 mm resulted in small increases (P < 0.05) in the intake of dry matter (DM) [26.0 cf. 27.8 g per kg runen digesta-free liveweight (RFLW)] and organic matter (OM) (23.8 cf. 25.5 g per kg RFLW). Increases in intake were paralleled by increases (P < 0.01) in loads of both rumen DM (29.7 cf. 33.9 g per kg RFLW, for 4 and 21 mm hay respectively) and OM (25.2 cf. 29.1 g per kg RFLW). The higher digesta load was associated with higher concentrations (P < 0.05) of DM (133.6 cf. 122.5 g per kg total digesta) and OM (114.9 cf. 103.8 g per kg total digesta) in the rumen, but not with a difference in the measured packing density of particulate matter. The increase in the intake of 4 mm hay was totally attributable to the greater DM load of rumen digesta because the fractional outflow rate of particulate matter was lower for the 4 mm hay (0.55 cf. 0.63/day) and the apparent fractional rate of digestion was similar (0.42 cf. 0.43/day) in sheep fed the two lengths of forage.
Calculation of the heritability of spinning fineness from phenotypic and genetic parameters of the mean and CV of fibre diameter
Authors: Butler KL , Dolling M
Published: November 2004

In sheep selection programmes where fibre diameter distribution measurements are available, such as when using the FDA method of assessing fibre diameter, spinning fineness (as defined by Anderson, S.L. (1976), J. Text. Inst., 67, 175-80) might be preferable to using mean fibre diameter as a sheep selection criteria. This paper uses a Taylor's expansion to obtain an approximation to the heritability of spinning fineness when the phenotypic and genetic parameters of only the mean and the coefficient of variation of fibre diameter are available. The approximation assumes that the mean and coefficient of variation of fibre diameter are both phenotypically and genetically independent. Approximations are also obtained for the genetic correlation between spinning fineness and mean fibre diameter, and between spinning fineness and coefficient of variation. Using the approximations, estimates of heritability of spinning fineness and of the two genetic correlations are calculated for published studies.
Glasshouse comparison of North Carolina phosphate rock, alkali-treated Christmas Island phosphate rock and single superphosphate as P fertilizers on an acidic soil
Authors: McLaughlin MJ , Dann PR , James TR , Garden DL
Published: November 2004

Three fertilizers were compared for their P release to pasture species growing on an acidic soil under glasshouse conditions. The fertilizers were a reactive apatitic phosphate rock (North Carolina, NCPR), a KOH-treated crandallite/millisite/goethite phosphate rock (Christmas Island C-grade ore, KC) and single superphosphate (SSP). Four successive crops were grown after an initial application of five rates of each fertilizer. The effect of P recycling on the yield responses to fertilizers was assessed in one set of treatments by replacing P removed in successive herbage harvests with P in sheep dung. NCPR and KC were not as effective as SSP for the first crop, and effectiveness decreased as fertilizer application rate increased. With subsequent crops (24) and for total dry matter production data (crops 1-4 combined) the relative effectiveness of NCPR depended on P recycling treatment. When P was removed at each harvest, NCPR was just as effective as SSP, but KC was less than one third as effective as SSP. When P was recycled after each harvest, NCPR was less effective than SSP, and KC was at best only one-third as effective as SSP. After three crops, the residual value of the three fertilizers was assessed against crop response to a fresh application of SSP. Residual value of all fertilizers was significantly increased by recycling P to the pots. KC had a significantly lower residual value than the other fertilizers, but there was no significant difference between the residual value of initially applied SSP and NCPR. Solubility of P in the SSP and KC fertilizers as measured by water and neutral ammonium citrate was well correlated with plant response to the fertilizers, while the performance of NCPR was underestimated by these methods.
Effect of superphosphate application on macro-nutrient and micro-nutrient concentrations in grazed stylo-native grass pasture in tropical Australia
Authors: Hendricksen RE , Gilbert MA , Punter LD
Published: November 2004

Soils of northern Australia are generally old, strongly weathered, and of low fertility status. Some knowledge of the status of nitrogen, phosphorus and sulfur and its effects on pasture productivity is available from small plot trials, but few detailed studies of macro-nutrient and micro-nutrient levels in grazed pastures have been reported. Such a study from a site near Mareeba in north Queensland has recently been completed. The major components of the pasture were kangaroo grass ( Themeda triandra), giant speargrass (Heteropogon triticeus) and the legumes, Stylosanthes scabra cv. Seca and S. hamata cv. Verano, which were oversown into the native grass pasture 6 years previously. Generally, the effects of superphosphate on nutrient concentration were minor compared with the effects of season, plant part and species. Superphosphate application increased concentrations of P and S, but decreased concentrations of Zn and Mo and the N/S ratio in both sets of legume and grass. There was no effect on the concentrations of N, K, Na, Ca, Cu and Co. Fertilizer effects did not often interact significantly (P < 0.05) with season, species and plant part (green leaf and stem). Seasonal changes in nutrient concentration were not consistent for all nutrients. As the growing season progressed from December to June, concentrations of the mobile nutrients, N, P, K, Na, Cl, S, Se and I decreased, the immobile nutrients Ca and Mo increased, but Mg, Cu and Co and the N/S ratio remained relatively constant. Both Zn and Mn concentrations remained constant with season in the legumes, but increased in the grasses. Season * species interactions were often significant for the grasses possibly due to the differing maturity patterns of kangaroo grass and giant spear grass. Cattle grazing the native pasture during the wet season are likely to be deficient in N, P, Na, S and Cu based on the nutrient concentrations in plucked pasture samples and published dietary requirements. However, cattle grazing productive stylo - native grass pasture which has received adequate single superphosphate are likely to suffer only from Na deficiency. At suboptimal levels of superphosphate, a deficiency of P in the diet is also indicated.
Wool fibre tenacity and its relationship to staple strength
Authors: Gourdie RG , Orwin DFG , Ranford S , Ross DA
Published: November 2004

Wool fibre tenacity and its relationship to staple strength was studied in a pen-feeding trial of 40 New Zealand Romney ewes. A method for estimating fibre tenacity is described based on normalizing fibre breaking load by cross-sectional area measured on fibre fracture-surfaces. The validity of this protocol was demonstrated by showing that (i) fibre diameter measured at the point of rupture was not significantly (P > 0.05) changed by breaking, and (ii) that the tenacity estimate was not significantly (P > 0.05) correlated with cross-sectional area variation along fibres, and (iii) showed lower fibre-to-fibre variation than other accepted measures of intrinsic material strength. The majority (83.5%) of the 1200 fibres broken in this study cleaved in smooth-planed fractures normal to the long axis of the fibre, the remaining fibres demonstrated axial-splitting following rupture. Tenacity did not differ significantly between the two break-types (P > 0.05). Tenacity demonstrated small negative correlations (P < 0.05) with fibre cross-sectional area and ellipticity. No change in tenacity (P > 0.05) occurred within fine, slow-growing 'wool-break' regions and tenacity did not vary significantly (P < 0.05) between body sites on sheep. Tenacity showed no significant variation (P > 0.05) with differential winter feeding, but significant variations (P < 0.01) of wool tenacity occurred between sheep. The sheepto-sheep differences in tenacity showed significant relationships with two indices of staple strength, work (P < 0.01) and peak-force (P < 0.01). Variability in fibre tenacity between sheep and its relationship to staple strength may provide some explanation of the origin of 'tender' and 'sound' wools.
A polymerase chain reaction assay for cucumber mosaic virus in lupin seeds
Authors: Wylie S , Wilson CR , Jones RAC , Jones MGK
Published: November 2004

Seed is the main source of infection of narrow-leafed lupin (Lupinus angustifolius) crops by cucumber mosaic virus (CMV). The ELISA procedure is currently used for large-scale, routine testing of lupin seed samples, but a more sensitive, reliable and labour-saving assay is needed which detects levels of seed infection as low as 0.1%. A Polymerase Chain Reaction (PCR) using ground dry seed samples was developed for this purpose. Primers based on concensus sequences of eight published CMV coat protein cDNAs (RNA3) of CMV subgroups 1 and 2 were used. The assay involved (1) a reverse transcription step for cDNA synthesis and (2) amplification of a specific fragment (482-501 bp depending on the strain) by PCR. Two methods of extracting virus from infected lupin material were used: (i) a rapid procedure which was effective for samples with higher levels of infection, e.g. infected leaves and 20.5% infected seed; (ii) a phenol-chloroform procedure, which led to greater sensitivity, enabling reliable detection of 0.1% seed infection. It detected CMV in 16 commercial seed samples (0.1-8% seed infection) belonging to seven cultivars from 12 different localities. Both methods were suitable for routine testing of the flour derived from grinding dry seed. On dissection of infected seeds, CMV was detected in the cotyledons and embryo and usually in or on the testa. The PCR assay detected virus from both CMV subgroups, but only subgroup 2 was found in lupin seed samples. The two CMV subgroups can be distinguished by digestion of amplified DNA with the restriction enzyme EcoRI; only CMV strains of subgroup 2 are digested to yield two fragments of size 330 and 170 bp.
Effect of short-term grain feeding on bovine body-fat colour: a cautionary note
Authors: Yang A , McLennan SR , Armstrong J , Larsen TW , Shaw FD , Tume RK
Published: November 2004

Seventeen Brahman steers were removed from pasture and fed a high grain diet for 8 weeks prior to slaughter. Carotenoid concentrations were determined in samples of serum and subcutaneous fat obtained either from live animals or at slaughter. At slaughter carcass fat colour was assessed according to AUS-MEAT specification. The concentrations of G-carotene in the serum of these animals fell rapidly (over 60%, P lt; 0.001) in the first 2 weeks on the grain diet and then plateaued. There was no change in either the concentrations of carotenoids in subcutaneous fat or in fat colour of these cattle during the whole period of grain feeding. The overall average liveweight gain was 0.59 kg/day. Failure to observe changes in concentrations of carotenoids was unexpected, and may be partly due to the fact that these cattle did not settle to the trial conditions in the feedlot, as indicated by the significantly higher cortisol concentration in their serum compared with the initial slaughter group. The implications of the outcome of this study are discussed.
The effect of sheep trampling and grazing on soil physical properties and pasture growth for a red-brown earth
Authors: Proffitt APB , Bendotti S , Howell MR , Eastham J
Published: November 2004

The experiment reported examined the effect of sheep trampling and grazing during wet conditions on soil physical properties and pasture growth over three winter seasons. The soil type studied was a structurally unstable sandy clay loam (a calcic red-brown earth) located in a dryland agricultural area (307 mm average annual rainfall) of Western Australia. Deferred grazing was investigated as a management option to reduce structural deterioration at the soil surface. Changes in soil physical properties as a result of trampling were related to soil water storage and pasture productivity. Infiltration rates were reduced as a result of sheep trampling, but there were no measurable changes in soil bulk density. Differences in pasture production between continuously grazed and ungrazed treatments were related to the amount of stored soil water, which in turn was related to infiltration rates. Pasture root growth during the season was also reduced as a result of trampling. Deferred grazing yielded the same quantity of biomass for feed over the reduced period available for grazing and proved to be a beneficial management practice since reasonably high infiltration rates were maintained. Results from the study also indicated that pasture must be adequately grazed to reduce leaf area later in the season when evaporative demand increases. A high leaf area over this time period may result in early pasture senescence.
Dietary lipids for ruminants: protection, utilization and effects on remodelling of skeletal muscle phospholipids
Authors: Scott TW , Ashes JR
Published: November 2004

Processes have been developed which protect dietary fat from ruminal metabolism, enabling greater quantities of lipid to be included in the diet of ruminants without causing deleterious effects on cellulose digestion and methane formation in the rumen. The inclusion of both protected fat and protected protein in the diet of lactating ruminants increased the percentage of milk fat and eliminated the reduction in protein content which is often observed as a result of feeding protected fat by itself. The inclusion of protected fat and protected protein in the diets of feedlot cattle increased metabolizable energy and rumen non-degradable protein. This resulted in improved feed conversion and dressing percent. There were substantial changes in the fatty acid composition of triacylglycerols of milk and adipose tissue as a result of feeding oil seeds protected from ruminal hydrogenation. The inclusion of protected fats containing linoleic or eicosapentaenoic acids in the diet of lotfed cattle resulted in major alterations in the fatty acid composition of the molecular species of muscle phospholipids. The significance of these changes in relation to phospholipid remodelling, signal transduction pathways and the characteristics of lipid-derived second messengers is discussed.