bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen fixation in chickpea. I. Influence of prior cropping or fallow, nitrogen fertilizer and tillage
Authors: Doughton JA , Vallis I , Saffigna PG
Published: November 2004

N fixation was measured in chickpea in a field experiment on the Darling Downs, Queensland. The 15N natural abundance method was used with barley as a non-fixing control crop. Chickpea was grown with 0, 50 and 100 kg/ha of applied N after pretreatments of either fallow or grain sorghum where sorghum stubble was either incorporated by cultivation, removed or retained on the surface with zero tillage. When chickpea was grown after sorghum both the percentage and amount of N in the tops derived from fixation were larger than after fallow. N fertilizer additions reduced per cent but not total N2fixation. Stubble management had no influence on total N2 fixed. There was a close inverse relationship (R2 = 0.95) between soil nitrate measured at establishment of chickpea and per cent of N derived from fixation. All treatment differences in per cent Nz fixation whether due to prior cropping, fallowing, N fertilizer or tillage could be explained through treatment influences on soil nitrate. Chickpea that had a plentiful supply of soil mineral N for growth accumulated significantly more plant N than plants dependent on N2 fixation. Chickpea grain yields were, however, unaffected by the source or quantity of plant N accumulated. Chickpea provided a positive soil N balance at high fixation rates and a negative balance at low fixation rates.
Temporal changes in growth enhancement by ractopamine in pigs: performance aspects
Authors: Sainz RD , Kim YS , Dunshea FR , Campbell RG
Published: November 2004

Ractopamine is a phenethanolamine with G-adrenergic agonist activity which stimulates growth in pigs. In order to test whether the growth-enhancing properties of ractopamine change over time, 40 Large White crossbred gilts (47.0 kg liveweight) were assigned to five treatment groups: CON, control diet for 6 weeks; RAC, ractopamine(20 mg/kg feed) for 6 weeks; C/R, CON for 3 weeks, then RAC for 3 weeks; R/C, RAC for 3 weeks, then CON for 3 weeks; ALT, CON for weeks 1, 3, and 5, and RAC in weeks 2, 4 and 6. The control diet was a commercial wheat and soy-based grower ration (13 MJ DE/kg, 16% crude protein, 0.9% lysine, 0.6 g available lysine/MJ DE); all pigs were fed 2.25 kg/day. Weekly measurements included body weight and P2 backfat (by ultrasound). Due to uncertainty about the data from the final week, results for weeks 1 to 3 and 3 to 5 are presented. Average daily gain (ADG) was increased by RAC (+16%) during the first 3 weeks, with no further improvement thereafter. C/R produced higher ADG (+21%) during weeks 3 to 5 compared with controls, and ALT tended to do the same (+12%, P < 0.10). Over the 5 week period, total weight gain was increased (P > 0.05) by RAC (+18%) and ALT (+15%), and tended to increase with C/R (+12%, P < 0.10) with no significant effect of R/C (+l0%, P > 0.05). There were no differences among groups in P2 backfat during the feeding period ( P > 0.05). With the exception of dressing percentage, which was increased by RAC, C/R and ALT ( P < 0.05), carcass and meat quality characteristics (carcass weight, P2 backfat, loin eye area, pH, colour, drip loss and protein solubilities) were unaffected by any of the treatments (P > 0.05). In conclusion, ractopamine stimulated growth in finishing pigs on restricted intakes; this effect diminished over time, and was more pronounced in older and heavier pigs. In addition, meat quality characteristics were unaffected.
Compensatory growth in sheep and cattle. II. Changes in body composition and tissue weights
Authors: Ryan WJ , Williams IH , Moir RJ
Published: November 2004

Compensatory growth can be due to increased protein deposition, reduced maintenance and greater feed intake. However, the contribution to and interaction between these mechanisms during compensatory growth is not clear. It was hypothesized that initial compensatory growth was due to reduced maintenance requirement and greater deposition of protein, after which compensatory growth was due to greater feed intake. Changes in the composition of sheep and cattle were measured during nutritional restriction and subsequent compensatory growth, and compared with the changes in control animals fed ad libitum throughout. At the end of the experiment the restricted cattle had compensated completely, and there was no difference in the body composition of the restricted and the control cattle. The restricted sheep did not compensate completely and were leaner than the control sheep. During nutritional restriction there was differential weight loss of carcase tissues in both the sheep and the cattle. The greatest losses were in the liver and the digestive tract in both species and in the skin of the sheep. It was concluded that the loss of these tissues reduced the maintenance requirement of the restricted animals and that the lowered maintenance requirement persisted during re-alimentation until these tissues had been fully repleted. Further, the repletion of these tissues required an increase in protein deposition, and it was a combination of these two mechanisms that was responsible for compensatory growth during the first 12 weeks of re-alimentation.
Evaluation of chemical desiccation as a selection technique for drought resistance in a dryland wheat breeding program
Authors: Regan KL , Whan BR , Turner NC
Published: November 2004

Previous studies have shown that some chemical desiccants and senescing agents, when applied to adequately watered cereals 10 to 14 days after anthesis, can be used to select lines with stable grain size (kernel weight) under post-anthesis water deficits. The present study evaluated the potential of one of these chemicals, potassium iodide (KI), to select for this character in a dryland wheat breeding program. Ninety-six F2-derived lines grown in the F6and F7 generations and 11 cultivars of wheat (Triticum aestzvum L.) were grown in two experiments at two medium-rainfall sites in 1988 and 1989 and sprayed with a 0.3% solution of KI when the grains had developed one-third in the lemma. Reductions in grain yield and thousand kernel weight due to treatment with KI were greater in 1988 than in 1989, probably due to the higher growing-season rainfall in that year. The reduction in grain yield as a result of desiccation was greater than the reduction in thousand kernel weight, but the correlation between the two was low (0.09 to 0.58) and non-significant in five out of the eight comparisons. There were considerable differences among genotypes in response to the desiccation treatment in the wetter 1988. Genetic coefficients of variation ranged from 5.6 to 12.9% for yield and 2.5 to 9.5% for thousand kernel weight. The ratio of the variance component estimates for the interaction between genotypes and desiccation treatment to the variance component estimates for genotypes was generally less than one. However, genetic differences in response to the desiccation treatment could be demonstrated in some experiments, particularly at one site and in the wetter of the two years. We conclude that the chemical desiccation technique can be used to select for post-anthesis drought resistance in a dryland breeding program. However, there are some limitations to the technique, and selection needs to be confined to wetter sites and seasons.
Relationships between carbon isotope discrimination, water use efficiency and transpiration efficiency for dryland wheat
Authors: Condon AG , Richards RA , Farquhar GD
Published: November 2004

Carbon isotope discrimination (-) has been shown to be negatively correlated with water use efficiency for wheat cultivars grown in the glasshouse. In the field this negative correlation has been confirmed for peanut but it has yet to be confirmed for wheat. Indeed, several field studies on wheat have shown positive (rather than negative) relationships between dry matter production and -. The aim of this study was to determine the relationship between - and water use efficiency for wheat grown in a dryland environment characterized by winterlspring-dominant rainfall and terminal drought. Eight genotypes chosen to give a range in - of c. 2.0x10-3 were grown on a red earth at Moombooldool in the Riverina region of New South Wales. Water use and above-ground dry matter (DM) were measured over the course of the season. Water use was partitioned into transpiration and soil evaporation and values of crop water use efficiency (WET) and transpiration efficiency ( WT) calculated. To account for the effect on WT of seasonal changes in the vapour pressure deficit of the air (D), crop coefficients (k) were derived by multiplying WT by the transpiration-weighted average daytime value of D for each genotype. During the preanthesis period, when there was little limitation of soil water supply on growth, there was a positive relationship between DM and -, as observed previously. The relationship between WET and - also had a positive (though non-significant) trend, but the relationship between k and - was negative, i.e. once the effects of variation in the ratio T/ET and seasonal changes in D were accounted for, the negative correlation between water use efficiency and - re-emerged. This apparent conflict between WET and k arose because genotypes with high - values developed their leaf area faster, with two important consequences. First, high - genotypes transpired more of their water supply during the winter when D was low and the exchange of water for CO2 more efficient. Second, transpiration made up a greater proportion of total water use by high - genotypes. The relationship between water use efficiency and - was further complicated as the crops depleted the soil water store after anthesis. During this period DM production tended to be greater in low - genotypes that had conserved soil water in the preanthesis period. However, DM production also remained high for two high - genotypes. The cause of this variation in post-anthesis growth among high - genotypes was not established.
Association between collection site soil pH and chlorosis in Lupinus angustifolius induced by a fine-textured, alkaline soil
Authors: Cowling WA , Clements JC
Published: November 2004

Collection site soil pH may be a useful predictor of tolerance in Lupznus angustifolzus to chlorosis induced by alkaline soils. We examined a range of genotypes from the Mediterranean region for their tolerance of an alkaline sandy clay loam (pH 8.8) from Merredin, Western Australia. Fifteen wild L. angustifolius lines, collected on a variety of soils that ranged in pH from 4.2 to 9.0, were compared with cultivars of L. angustifolzus and known alkaline-tolerant (L. cosentinii) and alkaline-sensitive (L. luteus) lupin species. Five-week-old seedlings varied greatly in chlorosis on the alkaline soil, from almost no chlorosis (as in L. cosentinzi cv Erregulla) to severely chlorotic (L. angustifolius line MJS176 from Spain). No lines were chlorotic after acid amelioration of the soil. Chlorosis score in wild L. angustifolius was not significantly correlated with soil pH at the collection site and was not associated with a particular soil texture, but there was a significant correlation between altitude of collection sites and chlorosis scores. Chlorosis-sensitive lines were from higher altitudes, had lower root and shoot fresh weight, were lower in Fe, Mn and K and were higher in Zn, P, and S in new growth than resistant lines. Chlorosis-sensitive lines also had the largest increases in fresh weight of roots and shoots in response to soil acidification. Genotypes with better root growth and therefore lower chlorosis symptoms on alkaline soil did not necessarily have the strongest root growth on acid ameliorated soil. Soil pH at the collection site in the Mediterranean region was not a reliable predictor of chlorosis in L. angustifolius induced by an alkaline fine-textured soil in Western Australia, although significant variation in tolerance to this soil was found within the species.
National survey of viruses in pastures of subterranean clover. II. Statistical methodology for large scale quantitative ELISA
Authors: Muller WJ , Helms K , Waterhouse PM
Published: November 2004

Statistical methodology was applied to a survey of time-course incidence of four viruses (alfalfa mosaic virus, clover yellow vein virus, subterranean clover mottle virus and subterranean clover red leaf virus) in improved pastures in southern regions of Australia, with samplings in each winter and spring over 3 years. The 100 samples per paddock collected at each time of sampling provided detection probabilities of 0.63 and 0.87 for 1% and 2% infection respectively. A microtitre plate design for ELISA was developed to include 60 field samples, 10 glasshouse-grown healthy control samples and 6 glasshouse-grown samples infected with the virus under examination. This design was used on 816 plates for each of the four viruses tested. The method used for identification of virus in sap of a plant sample from a particular paddock was that the ELISA reading was both significantly greater than healthy control readings, and an outlier in the distribution of readings of all sap samples from that paddock. It is argued that as the identification of uninfected samples as infected was highly unlikely, this double criterion method was superior to the use of each criterion separately. Use of significance above healthy control values as the sole criterion would have increased virus incidences by about 60%; use of outlier identification as the sole criterion would have increased virus incidences by about 30%. A generalized linear model with binomial errors and logit link was used for adjusting the virus incidences reported in the previous paper (Helms et al. 1993) for biases due to paddocks and/or districts not sampled on some occasions. This adjustment slightly increased overall incidences in all but one sampling and confirmed the time-course increase in incidence over the 3 years of the survey. The same model also proved to be the most appropriate for investigating the effects of year, season and district on virus incidence.
Resistance to potato leafroll virus infection and accumulation in potato cultivars, and the effects of previous infection with other viruses on expression of resistance
Authors: Wilson CR , Jones RAC
Published: November 2004

A selection of potato cultivars and breeding lines was evaluated for presence of resistance to infection with potato leafroll virus (PLRV) via viruliferous aphid vectors ( IR) and/or resistance to accumulation of PLRV antigen ( AR) in infected leaf tissue. Cultivars Aracy, Delcora, Omega and Spunta, and breeding lines BR63.15 and B71.240.2 carried both IR and AR , Bismark, Serrana INTA and L/T1 had alone and Delaware had AR alone. The other cultivars tested had neither. Within both the resistant and susceptible classes for AR, the level of PLRV antigen accumulation achieved varied with cultivar. Previous infection with potato virus X (PVX) or potato virus S (PVS) either alone or together did not diminish the expression of IR or AR. However, the presence of PVX sometimes significantly increased the accumulation of PLRV in susceptible cv. Desiree and this effect was most pronounced in mature leaves of older plants. In contrast, presence of PVX in susceptible cv. Desiree did not increase the numbers of plants becoming infected with PLRV. Identifying potato genotypes with and IR AR will help the Australian potato industry to select cultivars which become infected with PLRV more slowly under conditions of high infection pressure and/or are suitable for use as parental lines in breeding virus-resistant cultivars.
Pathogenic variability of Erysiphe graminis f.sp. hordei in South Australia, 1981-1985
Authors: Hossain MA , Rahman MS
Published: November 2004

Two techniques (mobile seedling nursery and detached leaf) were used to study the pathogenic variability of Erysiphe gramznis DC. ex Merat f.sp. hordei Em. Marchal in four barley growing areas of South Australia (S.A.). The mobile nurseries were conducted over 5 years (1981-1985) to monitor changes in the spectrum of virulence and individual gene frequencies. The race-specific resistance genes M1-a6, M1-k, M1-v and M1-ra were found to be susceptible to the pathogen populations in all surveyed areas. The same virulence genes spectrum (V-a6, V-k, V-v and V-ra) was present in the pathogen populations in the surveyed areas throughout the period of 1981-1984. During the 1985 season, one new virulence matching the resistance gene in cv. Forrest was detected. The resistance in cv. Galleon did not 'break down' over the cultivation period when its cultivation rose to 55% of the barley areas of S.A. The probable reasons for apparent durability of Galleon resistance are discussed. The relative frequencies of the matching virulence genes varied only slightly over time and space. The relative frequency of V-k was always almost 100%. The relative frequencies of V-a6, V-ra and V-v occurred at a higher rate than expected, since the matching resistance genes were not deployed in barley cultivars. The results of the detached leaf experiments (1982-1984) confirmed the virulence spectrum of the pathogen populations found in the mobile nursery experiments. Three individual single colony isolates from different cultivars (Clipper, Sonja and Goldmarker) were isolated and purified. Each isolate can produce a susceptible infection on other cultivars having different resistance genes in addition to its matching cultivar. Thus, each isolate carries more than one virulence gene. In the mobile nursery tests, the resistance gene M1-v (Varunda and LaMi) showed variable infection types (I.T.l-3), but in most cases it was moderately susceptible (I.T.3). Under the controlled conditions of the detached leaf tests, it gave an I.T.3 indicating the presence of virulence gene for M1-v in the pathogen populations. Reasons for this variable reaction are discussed. Midas with an ineffective gene (M1-a6) produced a resistant reaction to all isolates, suggesting the presence of additional resistance genes in the cultivar. The Mildew resistance genes M1-a, M1-a7, M1-a9, 141-al2, M1-g, M1-h, M1-(CP) and ml-o3 were found to be resistant in all surveyed areas in both experiments throughout S.A. Either the matching virulence genes for these resistance genes were absent or they were present at a very low frequency in the pathogen populations that could not be detected by the sampling techniques used.
Responses of spring wheat exposed to pre-anthesis water stress
Authors: Robertson MJ , Giunta F
Published: November 2004

Spring wheat cv. Yecora 70 was exposed to soil water deficits during three phases between emergence and anthesis: early (22 days after sowing to terminal spikelet), mid (terminal spikelet to anthesis) and late (early boot to anthesis). The objective was to quantify the effects of water stress on partitioning of above-ground biomass to the spike, the ratio between kernel number and anthesis spike weight, canopy expansion, radiation interception and phenology. This information can be used to test the assumptions used when modelling wheat growth and yield under water-limiting conditions. The extension rate of the lamina and pseudostem was reduced when more than 50% of the extractable soil water had been extracted from the root-zone, independent of the stage when stress was imposed. Stress reduced biomass accumulation more through a reduction of the amount of radiation intercepted than reduced radiation-use efficiency. The reduction in the amount of radiation intercepted was due to lower leaf area index, as the radiation extinction coefficient was similar under stress and non-stress conditions. Stress treatments reduced spike biomass at anthesis to 58-94% of that in the well-watered control, but had little effect on the pattern of biomass partitioning to the spike and the proportion of anthesis biomass as spike. Stress after terminal spikelet reduced the ratio of kernel number to anthesis spike weight by 50%, suggesting that reduced kernel number under stress may not be solely due to a restricted assimilate supply. This study showed that current assumptions are valid regarding the response of wheat to pre-anthesis stress in terms of canopy expansion, radiation interception and biomass partitioning to the spike. However, the constancy of the ratio of kernel number to anthesis spike weight was shown not to hold under water stress.
Evaluation of pre-harvest sprouting in triticale compared with wheat and rye using a line source rain gradient
Authors: Trethowan RM , Pena RJ , Pfeiffer WH
Published: November 2004

Field grown triticales, wheats and ryes were subjected to an artificial rain gradient with the aim of discriminating among different genotypes on the basis of their tolerance to wetting, measured as change in falling number (FN) and alpha-amylase activity (AA). Below-canopy gravity irrigation throughout the growing cycle ensured stress-free conditions. The rain gradient was created by overhead irrigation from a central water line or line source. Plots were sown perpendicular to the line source and sampled for AA throughout the gradient and over sampling dates. The gradient was also analysed for FN 30 days post physiological maturity (PM+30). Based on change in AA over both the gradient and sampling dates and change in FN at PM+30, genotypes tolerant to wetting were identified. The factors rnost important in conferring tolerance to wetting among triticales were spike angle, thousand-grain weight and FN levels. Whilst the line source offered good discrimination among triticales on the basis of change in FN and AA, it was not effective in distinguishing between wheat and rye lines.
Effect of maternal administration of salbutamol to sows on post-natal growth and carcass characteristics in the progeny
Authors: Kim YS , Sainz RD , Ferlazzo J , Tulloh NM
Published: November 2004

The effects of salbutamol administration to pregnant sows on post-natal growth and carcass characteristics of the progeny were investigated. Salbutamol (4 mg/kg diet) was fed to sows during the first (0 to 38 days, TI), second (39 to 78 days, T2) or third (79 days to term, T3) trimester of pregnancy. At birth, maternal administration of salbutamol had no effect on body weight, dressing percentage or weights of liver, heart, semimembranosus and semitendinosus muscle in proportion to body weight in the progeny. No significant effects of maternal treatment with salbutamol on body weight, dressing percentage, semitendinosus muscle weight in proportion to body weight and loin eye area were observed in the progeny at 21 days. P2 fat depth at 21 days was greater (P < 0-05) in TI than in controls. The percentage of type I fibres in the deep portion of semitendinosus muscle was higher (P < 0.05) in treatment groups as compared with controls: 27.4, 42.8, 36.9 and 36.0% in control, TI, T2 and T3 respectively. At slaughter (90 kg), carcass and meat parameters including length, P2 fat depth, meat colour and drip loss were not affected by maternal administration of salbutamol. However, loin eye areas were larger in T1 than in controls. Larger loin eye areas, coupled with numerically (but not statistically) significant heavier carcasses and lower backfats, resulted in greater estimates of carcass protein mass in TI pigs as compared with controls (P = 0.06).
The effects of supplementary copper and a mineral mix on the development of lupinosis in sheep
Authors: White CL , Masters DG , Paynter DI , Howell JMC , Roe SP , Barnes MJ , Allen JG
Published: November 2004

Lupinosis in grazing sheep is often associated with a potentially deleterious increase in the concentration of copper in the liver. Siromin�, a mineral mix developed by CSIRO for sheep on dry herbage and containing Cu at 116 mg/kg, was tested for its suitability for use with sheep consuming toxic lupin stubble, taking particular regard for dangers of Cu toxicity. There were three dietary treatments applied at two levels (either present or absent) to 40 Merino wethers for 8 weeks. Treatments consisted of adding Cu (10 mg Cu as CuS04/kg), minerals (25 g/kg as Siromin�) and toxic lupin stubble (50 g/kg) to a basal diet consisting of oaten hay and lupin seed and containing 3 mg/kg of Cu. Toxic lupin stubble decreased feed intake and growth, increased plasma activities of liver enzymes and increased plasma concentrations of protein, globulin, bilirubin, Cu and Zn. It also decreased concentrations of Zn and Fe in liver, but had no effect on Cu. The mineral mix had no adverse effects on any signs of lupinosis, and it did not increase liver Cu concentration at either level of dietary Cu. The mineral mix prevented the inappetence caused by lupinosis in sheep fed the low Cu basal diet. Cu treatment resulted in increased concentrations of Cu and Fe in liver, and exacerbated some signs of lupinosis. The results show that the mineral mix is safe to feed to sheep grazing toxic lupin stubble, and it may provide a practical means of supplying additional Zn. The exacerbation of signs of lupinosis by the addition of only 10 mg Cu/kg as CuS04 suggests that under field conditions the supply of Cu in the absence of suitable amounts of molybdenum and sulfur should be kept to a minimum.
Corrigendum - Seasonal variation in voluntary feed intake and growth in cashmere bucks fed ad libitum diets of low or high quality
Authors: Walkden-Brown SW , Norton BW , Restall BJ
Published: November 2004

The effects of season and diet quality on voluntary feed intake and growth were examined in mature cashmere bucks over a 16 month period at Wollongbar (29�S., 153� E.). Three-year-old bucks were individually housed under natural photoperiod and fed ad libitum diets of High (pelleted lucerne, CP 17.6%, ME 8.3 MJ/kg) or Low (pasture hay; CP 6.9%, ME 6.6 mJ/kg) quality, between July 1988 and Oct. 1989 (n = 6/treatment). Bucks on both diets exhibited a seasonal pattern in voluntary feed intake with maximal intakes during spring and summer, and minimal intakes during autumn. The pattern appeared to be circannual with high intakes during spring of both years. Liveweight also varied with season peaking in mid to late summer and reaching a seasonal nadir in late autumn or early winter. Change in liveweight was closely associated with digestible energy intake ( r = 0-87, P < 0.001) resulting in a growth cycle closely resembling that of voluntary feed intake. In both treatments, bucks lost weight throughout autumn, while growth rates were maximal between mid-winter and mid-spring. Diet quality did not alter the magnitude of the autumnal decline in liveweight with bucks losing 7.6% (Low) and 7.8% (High) of liveweight during this period. However, bucks on the high quality diet exhibited significantly elevated growth rates between mid-winter and mid-spring. We conclude that mature cashmere bucks exhibit an annual growth cycle with weight loss during autumn and maximal weight gains between mid-winter and mid-spring; that the growth cycle is driven primarily by changes in voluntary feed intake; and that increasing diet quality does not reduce the autumnal decline in liveweight but significantly increases liveweight gain during the seasonal peak in growth.
Mineral and amino acid composition of wool from New Zealand Merino sheep differing in susceptibility to yellowing
Authors: Aitken FJ , Cottle DJ , Reid TC , Wilkinson BR
Published: November 2004

The susceptibility of wool to yellowing was determined on samples from fleeces of 36 Merino wethers by a laboratory procedure involving incubation at 40�C for 5 days. The sheep, although originating from several different flocks, had been grazing together for 6 years. These susceptibilities were compared with the concentrations of suint and wax in the fleece, with fibre diameter, and with mineral concentrations in suint or yolk from the greasy wool. While the susceptibility of the fleeces was correlated with suint content (r = 0.852), the highest correlations were with the potassium concentrations in either suint before (r = 0.947) or yolk after (r = 0.938) incubation. There were significant differences in the concentration of potassium in the wool after washing, between the four most resistant and the four most susceptible fleeces, and in the effect of incubation on these potassium concentrations. No differences were detected in concentrations of other minerals in the clean wool nor in the relative proportions of amino acids.
How much is a genetically superior ram worth?
Authors: Wade C , Goddard M
Published: November 2004

The economic value of a genetic difference between rams was estimated for stud and commercial tiers in the Australian Merino industry. Discounted returns were predicted using the method of Hill (1974). Results were generated for breeding schemes considering natural mating (Scheme A), artificial insemination (Scheme B), the use of home-bred sires at daughter stud level (Scheme C) and the use of culled stud ewes in lower tiers (Scheme D). The effects of discount rate and ram flock life were assessed. The value of one extra unit of genetic merit in three traits (Clean Fleece Weight, Fibre Diameter and WOOLPLAN index score) was found for commercial, daughter and parent tiers. One extra kilogram of clean fleece weight (CFW) was worth around $817 for a commercial level ram (all Schemes) and up to $390000 for a parent level ram in Scheme B. The same improvement was worth $4 per semen dose used at commercial level, and up to $3977 at parent stud level (Scheme B). Increasing the discount rate devalued later returns, reducing the number of discounted expressions. Increasing ram flock life increased ram value but reduced semen value. The results are discussed for current industry practice and values obtained previously for commercial rams. The economic value of multiple ovulation and embryo transfer is considered.
Variation in reproduction and production of Poll Dorset ewes
Authors: Hall DG , Gilmour AR , Fogarty NM
Published: November 2004

Poll Dorset ewes were joined to Booroola Merino (n = 22) or Trangie Fertility Merino (n = 26) rams in single sire joinings during late summer/autumn of 1978, 1979, 1980 and 1981. Rams were changed each year and there were 1678 individual ewe joinings. A maximum of 527 ewes were used in any one year, and they represented 14 studs and varied in age, reproductive history and liveweight. The traits, litter size, maternal lamb survival, lambs weaned per ewe lambing and weight of lamb weaned per ewe lambing (kg at 100 days) were analysed for the effect of year, stud, age, lambs born and ewe liveweight. Litter size averaged 1-37, maternal lamb survival 0.70, and number of lambs weaned per ewe was 0.94. There were large variations in the reproductive traits due to year and stud and lesser effects due to age. Each extra kilogram of ewe liveweight at joining increased litter size by 0.012 and weight of lamb weaned by 0.39 kg, but had no significant effect on maternal lamb survival or number of lambs weaned. Multiple-bearing ewes weaned 0.72 more lambs and 16 - 2 kg more lamb weight than single-bearing ewes. Lamb survival was similar for singleand multiple-bearing ewes. Greasy fleece weight averaged 2.2 kg ewe-' and single bearing ewes produced 0.19 kg/ewe more than multiple-bearing ewes. Dystocia caused 53% and starvation/mismothering/exposure caused 23% of lamb deaths; the proportion of deaths due to starvation/mismothering/exposure increased with increasing ewe joining liveweight. The large variation between studs in reproductive performance partly reflected genetic differences between Poll Dorset flocks which could be exploited. Estimates of heritabilities ranged from 0.06 to 0.14 � 0.10 for the reproductive traits and were 0.10 � 0.12 for ewe liveweight and 0.16 � 0.20 for greasy fleece weight. However much of the between stud variation may also have arisen from early environmental effects. Estimates of repeatability ranged from 0.06 to 0.l5 � 0 05 for reproduction traits and were 0.44 � 0.06 for ewe liveweight at joining and 0.56 � 0.08 for greasy fleece weight.
Genetic parameters for Australian maternal and dual-purpose meatsheep breeds. II. Liveweight, wool and reproduction in Corriedale sheep
Authors: Brash LD , Fogarty NM , Gilmour AR
Published: November 2004

Performance of sheep from a large Corriedale stud flock was assessed. Weaning and yearling liveweights, greasy and clean fleece weights, clean fleece yield and average fibre diameter records on approximately 3000 animals representing 64 sires were analysed. Also scrotal circumference of 1009 rams representing 27 sires were analysed. Some 3740 reproduction records over 11 years, for 980 ewes representing 114 sires, were also analysed. Heritability estimates were 0 34 �0.07 for weaning liveweight, 0.132 � 0.04 for yearling liveweight, 0.32 � 0.07 for greasy and 0.29 � 0.07 for clean fleece weights, 0.534 � 0 10 for clean fleece yield, 0-56 � 0 10 for yearling and 0 62 � 0 - 14 for hogget fibre diameters and 0.l5 � 0.11 for scrotal circumference. The genetic correlations between liveweight and fleece weight ranged from 0.13 to 0.34, and those for liveweight and fibre diameter were close to zero. The genetic correlations of scrotal circumference with liveweight and wool traits were positive and moderate. Reproductive performance in the flock was high, with fertility 92% and litter size 1.62, resulting in 148% lambs born and 130% lambs tagged alive of ewes joined. Estimated heritabilities for reproduction traits were 0-03 � 0.02 for lambs born and for lambs tagged, and the component traits, fertility 0 01 � 0 -02, litter size 0.04 � 0.03 and neonatal lamb survival was zero. Lambing date had a heritability of 0.06 � 0.03. Estimates of repeatability ranged from 0-04 � 0-01 for fertility to 0.07% 0.02 for lambs tagged and lambing date. Predicted heritabilities for the average of 3.8 records per ewe generally agreed with those estimated for average ewe lifetime performance, which ranged from 0.02 � 0.08 for fertility to 0.12 � 0.09 for lambs tagged and 0.l3 � 0.09 for lambing date.
Release of sulfur from rice residues under flooded and non-flooded soil conditions
Authors: Lefroy RDB , Chaitep W , Blair GJ
Published: November 2004

Increased rice cropping intensity, due to shorter maturity varieties and shorter turn around times between crops, has lead to an increase in burning of rice straw. This can have significant short and long term effects on the productivity of the rice cropping system. A glasshouse experiment was conducted using an Aquic Haplustalf soil to study the release of S from different rice residues (straw and ash) under different water management conditions (non-flooded and flooded), and with and without the addition of S fertilizer. Rice straw residues (0.086 and 0.108%S) and ash produced from them (0.168 and 0.374%S), labelled with 35S, were used to investigate the importance of residue form and residue S concentration for the release of S. A loss of approximately 60% of the S from low-S straw and 40% from high-S straw was recorded on burning. The results showed that the addition of 6 kg S ha-1 as gypsum significantly increased grain yield across treatments. The addition of gypsum resulted in an increased S release from high-S straw residue under non-flooded conditions as measured by plant uptake, suggesting a priming effect of gypsum on S release from residues. The incorporation of straw and ash resulted in significantly increased grain yield in some but not all treatments. The percentage recovery of S in plants was higher in ash than in straw treated soil, but since S had been lost during burning, the absolute amount recovered (soil+plant) was higher in straw than in ash-treated soil. The 35S data indicate that if there is a critical S level for mineralization of rice straw, this level is less than the 0.086% in the residues used in this experiment.
Genotypic variation for stolon and other morphological attributes of white clover (Trifolium repens L.). Populations and their influence on herbage yield in the summer rainfall region of New South Wales
Authors: Jahufer MZZ , Cooper M , Brien LA
Published: November 2004

A random sample of 60 germplasm accessions from the Australian white clover germplasm collection was characterized in the field at Glen Innes, N.S.W. Genotypic variation for stolon and other morphological attributes was measured in one season. Herbage yield was evaluated over seven seasons to quantify the magnitude of accession-by-season interaction. There were significant (P < 0.01) differences among accessions, seasons, and accession-by-season interactions for herbage yield. Classification was used to group the accessions on their seasonal herbage yield. A summer active group, a winter active group and a group showing autumn activity for herbage yield were identified. There was significant (P < 0.01) variation among accessions for all plant attributes measured and their accession mean repeatability was moderate to high. There were strong genotypic correlations among the morphological attributes. Five of the morphological attributes (stolon density, stolon branching, plant spread, plant height, stolon thickness and leaf length) expressed a strong genotypic correlation with average herbage yield over seven seasons. The genotypic variation estimated for herbage production and plant attributes signifies the potential of the collection to be used as a source of variation for the genetic improvement of productivity and perenniality of white clover for Australian environments.
Wool follicle morphology and cell proliferation in New Zealand Romney sheep: a seasonal comparison of fleeceweight-selected and control rams
Authors: Holle SA , Harris PM , Davies AS , Birtles MJ
Published: November 2004

Effects of selection for high fleeceweight in the New Zealand Romney sheep were investigated in relation to the morphology of individual follicles and changes in the germinative cell population of the follicle bulb. Two-year-old Romney rams, 10 from each of two selection lines (Massey University fleeceweight-selected (FWT) and control (CLT) flock), were run together on pasture for a period from June to early December. At three times during this observation period (June, August and November) skin samples were taken from their midside flanks after local injection of bromodeoxyuridine (BrdU), to assess proliferation of bulb cells and several dimensional measurements of the follicle bulb and dermal papilla. FWT sheep had larger follicle dimensions than CLT sheep during winter and summer, with a greater number of proliferating bulb cells. Both flocks showed a seasonal change in follicle size, with a decline during winter, but the size of the dermal papilla was less affected than the germinative tissue area. Measurements of proliferation density (number of proliferating cells per area/volume of bulb tissue) suggest that changes in proliferation density do not contribute to flock differences in fleece production. However, during summer, FWT showed a 40% advantage over CLT sheep in hourly cell production based on data from three dimensional follicle bulb extrapolation. The different genotypes showed variations in width, as well as area of cortex and inner root sheath (IRS), measured across the top of the dermal papilla. The expression of these differences was further enhanced through seasonal influences, suggesting that there is an interaction between genetic/flock influences and seasonal influences on cell distribution to cortex and inner root sheath.
Evaluation of Bos indicus and Bos taurus straightbreds and crosses. I. Post-weaning growth of steers in different environments
Authors: Arthur PF , Hearnshaw H , Kohun PJ , Barlow R
Published: November 2004

Post-weaning growth of 186 steers comprizing straightbred Hereford (H x H) and Brahman (B x B), first-cross (B x H) and back-cross (H x BH and B x BH) was evaluated. The steers had been raised to weaning (8 months of age) by dams which grazed either high, medium or low quality pasture (pre-weaning pasture system) at Grafton, N.S.W. The steers were grown on pasture from time of weaning in one of three locations in New South Wales representing subtropical, temperate-good, and temperate-good to poor environments, and slaughtered when the average fat cover of the back-cross steers in each environment was 4-10 mm at the 12113th rib. Pre-weaning pasture system had a significant effect on post-weaning growth, with mean post-weaning (8-48 months of age) average daily gain (ADG) of steers from low (327� 8 g/day) being higher than that of steers from medium (304�6 g/day), which in turn, was higher than that of steers from high (276�9 g/day) quality pre-weaning pasture, indicating that steers from low and medium quality pastures exhibited compensatory growth. From 8 to 24 months of age, first-cross BxH steers had the highest ADG in all environments. The ranking of the other genotypes differed across environments. In the environment where growth rate was lowest (178 g/day for B x H), B x B and B x BH steers grew faster than H x H and H x BH steers; where growth rate was highest (584 g/day for B x H), the order was reversed; and where growth rate was intermediate (323 g/day for B x H), there were no significant differences in ADG among H x H, H x BH, B x BH and B x B steers. Steers from only two environments were retained after 24 months of age. Mean ADG from 8 to 36 or 48 months of age was not significantly different among straightbred and back-cross steers, but was lower than that for the first-cross steers. Genotype x environment interaction for liveweight at slaughter was not significant. First-cross B x H steers were 56 kg (11%) heavier (P < 0.05) than back-cross steers, which in turn, were 37 kg (8%) heavier (P < 0.05) than straightbred steers at slaughter.
Digesta flow studies in sheep fed two mature annual legumes
Authors: Li X , Kellaway RC , Ison RL , Annison G
Published: November 2004

Mature subterranean clover (Trifolium subterraneum cv. Junee) and Persian clover (Trifolium resupinatum cv. Kyambro) were fed to cannulated sheep. Flow rates of dry matter and nitrogen in the abomasum and ileum were estimated using a double marker method. Contents of hemicellulosic polysaccharides (xylose and mannose monomers) were higher in Kyambro than in Junee. Although Junee contained higher levels of total N and amino acids, the relative concentrations of cystine and methionine were markedly higher in Kyambro. Dry matter intakes and flow rates in the abomasum, ileum and faeces were similar on Kyambro and Junee. Dietary nitrogen intake was lower and endogenous re-cycled nitrogen higher on Kyambro than on Junee. Ileal flow of nitrogen was similar to nitrogen intake on Kyambro. Apparent nitrogen digestibility was lower in the whole tract and higher in the intestines on Kyambro. The higher apparent digestibility of nitrogen in the intestines of sheep eating Kyambro was associated with a greater proportion of nitrogen leaving the stomach coming from endogenous sources. The lower nitrogen digestibility of Kyambro in the whole tract indicated lower digestibility of dietary nitrogen, which was associated with higher contents of xylose and mannose.
Chemical composition and in vitro digestibility of lines of Lolium perenne selected for high concentrations of water-soluble carbohydrate
Authors: Radojevic I , Simpson RJ , StJohn JA , Humphreys MO
Published: November 2004

Differences in the water-soluble carbohydrate concentrations of herbage of northern European perennial ryegrass cultivars (Aurora, Melle, Cariad) grown under southern Australian conditions, and a New Zealand perennial ryegrass cultivar (Ellett) which yields well in southern Australia, were investigated in relation to their nutritive value. The water-soluble carbohydrates (WSC), total nitrogen, in vitro dry matter digestibility (IVDMD), neutral detergent fibre (NDF), and digestibility of NDF (NDFD) were measured in all cultivars. Aurora and Cariad exhibited higher WSC concentrations than the other cultivars, particularly during summer. This buffered the decline in IVDMD that was due to declining NDFD at that time of the year and resulted in an improvement in IVDMD of between 2 and 6%. Although WSC and nitrogen concentrations of the herbage were negatively correlated, this was due mainly to divergent seasonal variation in these components of the herbage.
Characterization of the high α -amylase levels in grain of the wheat cultivar BD 159
Authors: Mares DJ , Mrva K , Panozzo JF
Published: November 2004

TThe advanced wheat breeding line BD 159, from Victoria, exhibited a wide variation in falling number values at trial sites in 1990 when corresponding values for standard cultivars were uniformly high. The variable and unpredictable behaviour of BD 159 appears to be typical of a number of advanced lines and parental stocks from Australian breeding programs. The grain samples of BD 159 with low falling numbers had elevated levels of a-amylase which was distributed evenly in the proximal and distal halves of the grains. This distribution pattern, which was quite distinct from the steep gradient in a-amylase activity typical of germinated grains, and the absence of any evidence of sprouting indicated that the anomalous behaviour of BD 159 is a new and different form of the late maturity a-amylase syndrome previously described in wheat varieties such as Spica and Lerma 52. The high levels of a-amylase were reproduced at Narrabri in northern New South Wales when plants were transplanted from the field and allowed to ripen in a cool temperature glasshouse. Plants which were left to ripen in the field produced grain with a very low a-amylase activity.
Long-term effects of lime on pasture yields and response to phosphate fertilizers on eight acidic soils
Authors: Holford ICR , Crocker GJ
Published: November 2004

Eight experiments on acidic soils of the Northern Tablelands of New South Wales were carried out to measure lime effects on clover-based pastures and their response to fertilizer phosphate (P). Each experiment lasted 3 years. The seven soils deficient in P all responded to lime in the first year, and pasture yield responses were associated with lime-induced increases in isotopically exchangeable or soluble soil P or both. Three of these soils were also relatively high in soluble aluminium (Al) or manganese (Mn), and the lime-induced suppression of these toxic cations probably also contributed to the beneficial effects of lime. Negative effects of lime on fertilizer P response were more frequent than positive effects, and tended to occur on higher A1 soils. Lime eliminated the need for fertilizer P on at least three P-deficient soils during the 3 year period of the experiments, and this was also associated with increases in availability and uptake of soil P. Lime suppressed P sorptivity in all soils, but this caused an increase in fertilizer P effectiveness in only two soils (in the first year). Hence, the positive effect of lime on soluble soil P, which occurred on all soils and which would tend to lower fertilizer P effectiveness, seemed to be dominant over its negative effect on soil P sorptivity. Residual effects of lime and fertilizer P were similar, both declining after the first year, with five soils still responsive in the third year.