bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures
Authors: Proffitt APB , Jarvis RJ , Bendotti S
Published: November 2004

The effect of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures was examined over an 8 week period when the soil was wet following winter rains. The experimental site was located at Merredin in Western Australia where the average annual rainfall is 307 mm. A previous long-term tillage and gypsum trial at the experimental site had resulted in the development of contrasting topsoil structures. Three grazing treatments were imposed at the trial site: grazing at the normal high stocking rate (8 DSE ha-1), grazing at half the normal stocking rate (4 DSE ha-1), and no grazing (where pasture was mown to simulate grazing without trampling). Topsoil structure was assesed by measuring water-stable aggregation (> 2 mm diameter aggregates), the relative contribution of dispersion and slaking to structural instability (measured as soil strength on < 2 mm fine earth soil fractions), steady-state infiltration rates (at 10 mm tension), and in situ soil strength characteristics (measured as penetration resistance). At the end of the grazing period, all structure attributes measured showed that topsoil structure had been damaged as a result of sheep trampling. The magnitude of such structure damage was affected by the initial physical condition of the soil and stocking rate. When compared with ungrazed pasture, there was a greater decline in structural condition as a consequence of grazing on less well-structured soil than on better-structured soil. Halving the normal stocking rate reduced the degree of structure damage on both soils. Within-season variability in soil hydraulic properties was large. The temporal changes in infiltration rates were attributed to changes in drainage pore volume brought about by the growth and decay of pasture roots, the formation and disruption of a surface crust, and the processes of soil compaction and remoulding resulting from animal trampling (no direct measurements were made). The variability in hydraulic behaviour found in this study emphasizes the need to maintain consistent sampling dates and soil water contents at sampling in long-term studies on soil structure changes.
Losses in herbage and seed yields caused by subterranean clover mottle sobemovirus in grazed subterranean clover swards
Authors: Ferris DG , Jones RAC
Published: November 2004

Subterranean clover (Trifolium subterraneum L.) was grown in swards into which small plants infected with subterranean clover mottle sobemovirus (SCMoV) were transplanted. Initial spread was mainly to plants adjacent to infected transplants and occurred during grazing and trampling by sheep. New sites of infection subsequently formed away from the original infection sites. Spread occurred mainly in spring and its extent varied with cultivar, site and year. Final SCMoV incidence in swards ranged from 17% of plants infected by isolate MJ in cv. Karridale in 1993 to 60% by isolate P23 in cv. Dinninup in 1991. With cvv. Dinninup and Junee, in two experiments SCMoV-infection decreased yields within patches with symptoms by 11-26% (herbage) and 5-31% (seed); in one of these experiments infection decreased overall yields of herbage by 9-10% and seed by 10-31%. In an experiment with cvv. Dalkeith and Woogenellup, SCMoV-induced overall herbage yield decreases of 10-13% were recorded despite extensive virus spread to control swards; yield losseswithin affected patches were 20-28% for herbage and 19% for seed. In an experiment with cw. Karridale and Woogenellup, SCMoV-induced yield losses within patches with symptoms were 38-44% for herbage and 15-41% for seed. Decreased seed size (mean seed weight) and fewer seeds both contributed to the diminished seed yields. Estimates of the effects of different levels of SCMoV infection on herbage yields were obtained for cv. Woogenellup by plotting dry weight data from (i) individual quadrats against percent plants with symptoms within them and (ii) whole plots against percent plot infection determined by ELISA. Losses increased in proportion to the level of infection. SCMoV infection of subterranean clover pastures not only decreases the feed available but also the seed bank which, when compounded over several years, leads to pasture deterioration. Heavy grazing, reseeding the pasture with susceptible cultivars and extended growing seasons are all likely to magnify SCMoV-induced losses.
Differential responses of Australian wheat cultivars to cadmium concentration in wheat grain
Authors: Oliver DP , Gartrell JW , Tiller KG , Correll R , Cozens GD , Youngberg BL
Published: November 2004

Cadmium concentration in grain was studied for wheat cultivars grown nationally in the Interstate Wheat Variety (IWV) experiments (1988 and 1989) and cultivars grown in the Western Australian (WA) experiments (1990-1992). These experiments covered a range of differing soil and environmental conditions. The adaptation of these cultivars to changes in cadmium potential at a site was determined. Significant cultivar effects were identified, but these were less significant than the site effects. The Cd concentrations in grain exceeded the current Australian maximum permitted concentration (MPC) of 0.05 mg kg-1 at one site in the IWV experiments while the concentration exceeded the MPC at a larger proportion of sites in the WA experiments. Several trends in cultivar accumulation of Cd in grain were evident. Reeves and Kulin were found to have the highest Cd concentration at a number of sites for several years in both the IWV and WA experiments. The similar pedigrees of these two cultivars suggest that while wheat breeders were selecting for certain traits during the breeding selection process, they were inadvertently selecting for the ability to accumulate Cd. In the 1992 WA cultivar experiments, generally Aroona had the highest Cd concentration in grain. Aroona has different pedigree to Reeves and Kulin. Several of the cultivars that were low Cd accumulators also had similar pedigrees. This indicates that there is potential for selecting lines that are low Cd accumulators to be grown in areas where Cd accumulation in grain is a problem.
Effects of barley yellow dwarf virus on the yield of winter wheat
Authors: Banks PM , Davidson JL , Bariana H , Larkin PJ
Published: November 2004

Yield responses were measured of six winter wheats to field infections with Barley Yellow Dwarf Virus (BYDV). In addition to the natural incidence of virus, the range of infection levels was widened by aphicide spraying of some plots and the addition of artificially propagated viruliferous aphids to others. Significant grain yield losses attributable to natural infections by BYDV were found for all wheats despite the main infection period being in the spring. The addition of viruliferous aphids only marginally decreased yields further. Spraying with aphicides did not exclude infection but did reduce the incidence of BYDV and increase yields. A significant negative linear correlation between grain yield and percentage infection applied to each wheat genotype. The slope of the yield response appears to be a more useful measurement for comparing tolerance to BYDV of differing cereal lines than do proportional yield losses. Of the six wheats tested, Lawson, Birch 41, Birch 75, Owlet and Isis had similar tolerances to BYDV, despite substantial differences in absolute yields, while W71 was considerably more vulnerable. The mean natural incidence of BYDV in the main trial was 67%, producing an expected grain yield loss of about 2.2 t ha-1 for W71 and about 1.1 t ha-1 for the other five wheats. Effects on grain protein and potential control measures are also discussed.
Responses in ciliated protozoa and rumen fermentation in sheep supplemented with barley plus virginiamycin
Authors: Nagaraja TG , Godfrey SI , Winslow SW , Rowe JB
Published: November 2004

An experiment was conducted to determine the changes in the population of ciliate protozoa and the pattern of rumen fermentation in sheep fed a supplement of barley grain on its own or containing virginiamycin. There were three treatment groups with a total of 25 sheep housed in individual pens. All animals were fed chaffed wheaten hay to a maximum of 1.4 kg head-1 day-1. One group received no grain supplement (n = 5), one barley grain (n = 10) and the third barley plus virginiamycin (40 g/t grain; n = 10). The amount of grain was gradually increased over a period of 5 days to a maximum of 700 g of barley or barley plus virginiamycin on day 5. Grain (700 g/head) was then fed twice weekly for a further 18 days. Samples of rumen fluid were taken on days 1, 2, 3, 5*, 6, 9*, 12*, 23* and 24 (* signifies days when 700 g barley was fed). In sheep supplemented with barley the population density of ciliate protozoa was increased (P < 0.01) from day 3 of the 5 day introduction to grain (approximately 170x104 protozoa/mL at day 5), but the increase was not sustained when grain was fed at intervals of 3 or 4 days. In sheep supplemented with barley plus virginiamycin, the population density of ciliate protozoa was increased significantly (P < 0.01) only at days 5 and 6 of the experiment (approximately 100x l04 protozoa/mL at day 5). Sheep supplemented with barley plus virginiamycin at day 5 had a higher concentration of L-lactate (P < 0.05) at 6 and 12 h and propionate (P < 0.05) at 6, 9, 12 and 24 h than sheep supplemented with barley alone. It was concluded that virginiamycin was inhibitory to protozoa during the introduction to grain, and L-lactate accumulation in the rumen of sheep supplemented with barley plus virginiamycin may be a result of altered fermentation associated with reduced numbers of protozoa.
The effect of supplementary minerals, retinol and α -tocopherol on the vitamin status and productivity of pregnant Merino ewes
Authors: Kumagai H , White CL
Published: November 2004

Four hundred and twenty Merino ewes were divided into four treatment groups: control (NaCl at 175 g head-1 week-1 ), vitamins (salt containing 0.24 g/kg retinol plus 12 g/kg �-tocopherol), minerals (a multi-element mineral mix (Siromin ) at 175 g head-1 week-1) and vitamins plus minerals (mineral mix plus vitamins) in a two by two factorial design. Treatments started in November prior to mating and finished in May 1 week prior to lambing. Measurements of vitamin status and animal productivity were made on ewes and foetal and weanling lambs. Compared with salt, the mineral mix increased ewe body weight by up to 3% ( P < 0.05), annual wool growth by 4.4% ( P < 0.001) and birth and weaning weights of single lambs by 7.3% ( P < 0.01) and 3.7% (P < 0.05) respectively. Since ewes had been given selenium and cobalt bullets at weaning, the results suggest either that the bullets do not offer protection for the lifetime of the ewe and that additional bulleting is warranted, or that other minerals are limiting production. As pastures dried off, the concentrations of �-tocopherol and G-carotene fell and this was reflected in a decline in the concentrations of �-tocopherol and retinol in liver. However, the liver stores at the beginning of summer were sufficient to prevent the appearance of clinical signs of vitamin deficiency. Vitamin supplementation significantly increased the concentration of vitamins in the plasma and liver of ewes ( P < 0.001)) but it had no significant effect on ewe reproductive performance or on ewe or lamb body weights or wool growth. Vitamin supplements increased the concentrations of retinol and �-tocopherol in the liver of foetal lambs, but even with supplements the levels remained well below normal adult reference values.
Phytophthora in Australia
Authors: Irwin JAG , Cahill DM , Drenth A
Published: November 2004

Phytophthora spp. are one of Australia's most serious plant pathogens, causing well in excess of $200 million in lost production annually across all of our plant-based industries. Of the more than 50 species of Phytophthora recorded worldwide, over 20 are present in Australia. All species, along with their hosts, distribution and current control measures have been tabulated. Use of molecular markers to analyse population genetic structure has shown that most of these pathogens have been introduced from overseas, and become widely distributed in Australia within relatively short periods of time. The review highlights the general biology of Phytophthora spp. and their impact on agricultural production in Australia, with particular emphasis on the genetics of host/pathogen interactions, population genetic structure and reproduction of Phytophthora populations in Australia. The review highlights the role molecular technologies may play in developing an understanding of host-pathogen recognition and pathogenesis in Phytophthora. Three case histories, involving P. sojae, P. medicaginis and P. cinnamomi, have been developed to provide insights into current levels of understanding, and to identify gaps in our knowledge. Current control measures are summarized and possible new avenues of control discussed.
Inheritance of anthracnose resistance in the tropical pasture legume Stylosanthes hamata
Authors: Iamsupasit N , Cameron DF , Cooper M , Chakraborty S , Edye LA
Published: November 2004

Eight tetraploid accessions of the tropical pasture legume Stylosanthes hamata with varying levels of response to the anthracnose pathogen (Colletotrichum gloeosporioides) were crossed in a half diallel scheme. Based on mean disease severity ratings (MDR), two parents, 55830 and 75164, were grouped as resistant (R), 55828 and 65365 were susceptible (S), and the remaining four, cvv. Verano and Amiga and 65371 and 75162 were moderately resistant (MR). Of these, the two resistant parents appear to carry different genes for resistance. The MDR of 20 of the 28 F2 populations was significantly different from their mid-parent MDR and the expression of resistance, in most cases, was recessive. Only a limited number of the F2 distributions for crosses between RxS, RxMR and MRxS parents conformed to a single gene model. The inheritance patterns observed were considered to be predominantly quantitative. Variation for general combining ability, was as large as or larger than that for specific combining ability suggesting that a large proportion of the genetic differences among the parents was additive. The finding that the resistance is inherited as a quantitative trait is consistent with results on the epidemiology of anthracnose in tetraploid S. hamata.
Effect of heat shock during grain filling on grain quality of bread and durum wheats
Authors: Borghi B , Corbellini M , Ciaffi M , Lafiandra D , Stefanis Ede , Sgrulletta D , Boggini G , Fonzo Ndi , De Stefanis E , Di Fonzo N
Published: November 2004

In southern Europe the Mediterranean climate is responsible for the remarkable variability in both yield and quality from year to year and also from location to location, but it offers also a unique opportunity for the production of high-quality wheats which are deficient in the European Economic Community. This study was conducted to determine the role of the fluctuation of temperatures during grain filling on the rheological properties of bread and durum wheats (Triticum aestivum and Triticum turgidum) as evaluated with a Chopin alveograph. During the 1991-92 season, four cultivars of bread and durum wheat were grown in several locations scattered along the Italian peninsula and the island of Sicily. In each location different temperature profiles were imposed during grain filling by anticipating or delaying sowing date or by covering the plots with plastic tunnels. Viscoelastic properties, evaluated by the variations in W, P and L alveograph parameters were significantly affected by the imposed treatments. In presence of a long period of temperature in the range of 30-35�C a dough 'strengthening' effect was observed, while frequent episodes of daily maximum temperatures above 35�C led to a dough 'weakening' effect. These results observed both in durum and bread wheat confirm those firstly detected on bread wheat in Australia in areas charcterized by a Mediterranean-like climate. The practical relevance of these effects differs in the two species: an increase of dough strength is considered detrimental in breadmaking quality, while it exerts a positive effect in pastamaking quality.
Double muscling in cattle: a review
Authors: Arthur PF
Published: November 2004

Muscular hypertrophy of genetic origin in cattle, commonly referred to as double muscling, is reviewed in this paper with a discussion on its possible use in beef and dairy-beef production systems in Australia. The double-muscled syndrome is an inherited condition, and is found in many breeds of cattle. The highest frequency of occurrence is found in the Piedmontese and Belgian Blue breeds. Deliberate effort was made in the last few decades to increase the frequency of double muscling in these two breeds. The syndrome is associated with some production problems such as reduced fertility, dystocia and reduced calf survival. Cattle showing the syndrome, however, have higher meat yield, a higher proportion of expensive cuts of meat, and lean and very tender meat. The superior meat and carcase characteristics have been responsible for their widespread use in Europe, where premium price is paid for double muscled carcases. Piedmontese and Belgian Blue cattle have recently been imported into Australia. These double-muscled breeds will have a role to play in beef and dairy-beef production systems in Australia. For commercial production it is recommended that the breeding female herd be kept free from double muscling. A terminal sire breeding system is suggested, whereby normal females are mated to double muscled sires and all progeny slaughtered.
A technique to quantify and characterize the density of fibres and follicles in the skin of sheep
Authors: Nagorcka BN , Dollin AE , Hollis DE , Beaton CD
Published: November 2004

A description is given of a non-destructive technique to count fibres and quantify their relative positions in the skin of sheep by making impressions of the skin surface of live sheep. Each impression contains within it clear morphological structures caused by individual wool fibres as they emerge from individual follicles, and clusters of wool fibres emerging from follicle bundles. Individual fibres and clusters of fibres can also be seen to be grouped together forming 'follicle groups'. The detailed accuracy of the impressions is confirmed by examining scanning electron microscope (SEM) images of a model of the skin obtained using the skin impression, and by examining SEM images of the impression itself. The impressions of individual fibres and clusters of fibres (produced from follicle bundles) appear to be countable using image analysis software. The new technique provides a low cost method (i.e. low relative to the cost of analysing skin biopsies) for measuring the density of fibres and fibre bundles, and the number of fibres per bundle in the skin. The measurements are expected to be of significant commercial interest to wool breeders.
Effect of reproductive state and concentrate supplementation on liquid and particulate turnover in the rumen of ewes given ammonia treated straw
Authors: Perez JF , Gasa J , Castrillo C , Guada JA
Published: November 2004

Rates of passage of liquid and particulate markers (Co-EDTA, Cr mordanted fibres and Yb) were measured in ewes at late pregnancy, lactation and non-breeding status. Animals were given ammonia treated barley straw ad libitum supplemented daily with 250 and 550 (pregnancy), 550 and 850 (lactation) and 250, 550 and 850 (non-breeding) g of concentrate. The effect of the reproductive state was analysed only on ewes fed on 550 g of concentrate. Lactating ewes showed a higher voluntary straw intake (970 g/day) than pregnant or non-breeding ewes (720 and 790 g/day respectively), but there were not significant differences in the OM digestibility (OMD) among reproductive states. Increasing concentrate supplementation promoted significant decreases in the voluntary intake of straw, associated with an enhanced OMD ( P < 0.05). Fractional outflow rates (FOR/h) were higher in pregnant and non-breeding than in lactating ewes, although differences were only significant ( P < 0.01) for Chromium derived values. Ewes given 250 g of concentrate showed lower ( P < 0.05) FOR than those given 550 and 850 g/day. Results support the idea that in ruminants fed on low quality roughages, voluntary dry matter intake is mainly restricted by rumen capacity, although the energy status of the animals might influence the extent of this restriction.
Response to phosphorus fertilizer compared under grazing and mowing
Authors: Cayley JWD , Hannah MC
Published: November 2004

The response to phosphatic fertilizer of a pasture based on perennial ryegrass, subterranean clover and phalaris was assessed over 4 years. The pasture was established on a previously unfertilized area. Single superphosphate was applied at five rates. In addition there was an unfertilized treatment. The highest rate of fertilizer, expressed as elemental phosphorus (P), was reduced from 100 kg/ha in years 1 and 2 to 60 and 40 kg/ha in years 3 and 4 respectively. Each year total pasture drymatter (DM) production was measured during a 6-month growing season from early winter to late spring under four systems of defoliation: mown monthly (MI), mown every 2 months (M2), mown every 3 months (M3) or set stocked with 1 year old sheep (G). Grazed plots were stocked at 10, 14 or 18 sheep/ha in 3 of the years, and at 8.75, 12.25 or 15.75 sheep/ha during the remaining year. The production of mown pasture generally decreased with increasing frequency of cutting, and was always less than the production of grazed pasture. Mean values for MI, M2, M3 and G were 2.85, 4.35, 5.44 and 6.86 t DM/ha respectively. The absolute and marginal responses to fertilizer (kg DM/kgP) were always greater for the grazed treatments. This suggests that data from mowing trials seriously underestimate the fertilizer response of grazed systems. The amount of fertilizer required to reach a given proportion of potential yield response did not differ between the systems in the first 3 years, but in year 4, more fertilizer was required by the grazed system to reach a given proportion of potential yield (P < 0.01. Strategies for correcting the response curves of the mown treatments are considered.
Microbiological aspects of sugarcane yield decline
Authors: Magarey RC
Published: November 2004

Sugarcane is an important Australian crop earning over $1.8 billion in export revenue annually. The crop is grown as a monoculture, and much of the production area has been continually cropped for over 60 years. Increasing production trends plateaued in the 1970s and soil based constraints now reduce industry income by $200~1 annually. The condition, termed sugarcane yield decline (YD), is similar to replant diseases in other crops. Large growth responses to soil fumigation, soil solarisation, and the application of fungicides, suggest that soil microbiology is intimately involved. Research has identified a previously unclassified oomycete, Pachymetra chaunorhiza, as a new sugarcane root pathogen. Additional root pathogens identified include Pythium arrhenomanes and various nematode species. Other organisms which appear to be involved in YD, are discussed.
Wheat protein trends in northern and central NSW, 1958 to 1993
Authors: Verrell AG , O'Brien L
Published: November 2004

According to the Australian Wheat Board, the average level of protein in the Australian wheat crop is declining with a marked decline in the Australian Standard White (ASW) grade. Data on wheat protein concentration were collected for 125 wheat receival sites along with wheat production, area sown to wheat, and monthly rainfall in northern NSW from 1958 to 1993. Protein trends of the major wheat segregations were examined along with the effect of year-to-year variation in winter rainfall and the impact of the segregation and storage system on trends in protein. The variation in protein content was inversely associated with variation in yield (-1.5%/t. ha) and was attributed to year-to-year variation in winter rainfall (May to October). For the period for which the wheat segregation system has operated, 1970 to 1993, ASW in the study region has apparently declined at the rate of -0.ll%/year. Expansion of the storage and segregation system and access to load-by-load protein testing in the early 1980s led to a large proportion of wheat that had been delivered into ASW, in the 1970s, being redirected into higher protein segregations. Redistribution of wheat receivals in the 1970s around the 11.5% protein level removed this distortion and indicated a rate of decline for wheat <11.5% of -0.06%/year. In the absence of segregations, the weighted average protein was declining at a rate of -0.08%/year and accounting for year-to-year variation in rainfall the underlying trend in protein was 0.04%/year. Allowing for the year-to-year variation in rainfall and the limitations of the segregation system the decline in protein in wheat redistributed below 11.5% was 0.05%/year and may reflect a run-down in soil fertility. Wheat in this category was increasing significantly, over time, as a proportion of total receivals.
Pre-harvest sprouting tolerance in wheat in the field and under rain simulation
Authors: Trethowan RM , Rajaram S , Ellison FW
Published: November 2004

Segregating and fixed lines, selected under controlled conditions in the rain simulator at the Plant Breeding Institute (PBI), were evaluated and selected further in the field at the International Maize and Wheat Improvement Centre's (CIMMYT) Toluca field station, Mexico. The field evaluation was conducted under natural rainfall to confirm the effectiveness of the selected tolerance. Plots at Toluca were sampled at 10 and 21 days post physiological maturity. Percent visible sprouting was determined and a sprouting index calculated. After the final sampling date, plots were harvested and falling number was measured. Standard partial regression coefficients indicated that plant maturity was the major influence on visible germination (r = 0.80***) among families, whilst fluctuations in minimum temperature in the 10 days immediately following physiological maturity had the greatest effect on sprouting tolerance both within families (r = -0.78***) and across all data points ( r = -0.52***). The influence of temperature, rainfall, and plant maturity on falling number measurements was less well defined, with fluctuations in minimum temperature prior to ( r = -0.22***), and maximum temperature following (r = 0.27***), physiological maturity the only major influences. Preharvest sprouting tolerance determined by rain simulation at PBI in 1993 correlated significantly with field estimates of tolerance at Toluca in 1994 (r = 0.76***).
The value of skill in seasonal climate forecasting to wheat crop management in a region with high climatic variability
Authors: Hammer GL , Holzworth DP , Stone R
Published: November 2004

In Australia, and particularly in the northern part of the grain belt, wheat is grown in an extremely variable climate. The wheat crop manager in this region is faced with complex decisions on choice of planting time, varietal development pattern, and fertiliser strategy. A skilful seasonal forecast would provide an opportunity for the manager to tailor crop management decisions more appropriately to the season. Recent developments in climate research have led to the development of a number of seasonal climate forecasting systems. The objectives of this study were to determine the value of the capability in seasonal forecasting to wheat crop management, to compare the value of the existing forecast methodologies, and to consider the potential value of improved forecast quality. We examined decisions on nitrogen (N) fertiliser and cultivar maturity using simulation analyses of specific production scenarios at a representative location (Goondiwindi) using long-term daily weather data (1894-1989). The average profit and risk of making a loss were calculated for the possible range of fixed (i.e. the same every year) and tactical (i.e. varying depending on seasonal forecast) strategies. Significant increase in profit (up to 20%) and/or reduction in risk (up to 35%) were associated with tactical adjustment of crop management of N fertiliser or cultivar maturity. The forecasting system giving greatest value was the Southern Oscillation Index (SOI) phase system of Stone and Auliciems (1992), which classifies seasons into 5 phases depending on the value and rate of change in the SOI. The significant skill in this system for forecasting both seasonal rainfall and frost timing generated the value found in tactical management of N fertiliser and cultivar maturity. Possible impediments to adoption of tactical management, associated with uncertainties in forecasting individual years, are discussed. The scope for improving forecast quality and the means to achieve it are considered by comparing the value of tactical management based on SO1 phases with the outcome given perfect prior knowledge of the season. While the analyses presented considered only one decision at a time, used specific scenarios, and made a number of simplifying assumptions, they have demonstrated that the current skill in seasonal forecasting is sufficient to justify use in tactical management of crops. More comprehensive studies to examine sensitivities to location, antecedent conditions, and price structure, and to assumptions made in this analysis, are now warranted. We have examined decisions related only to management of wheat. It would be appropriate to pursue similar analyses in relation to management decisions for other crops, cropping sequences, and the whole farm enterprise mix.
Changing perceptions of the effect of plant phenolics on nutrient supply in the ruminant
Authors: Lowry JB , McSweeney CS , Palmer B
Published: November 2004

Mammalian metabolism of plant phenolics, initially studied in monogastric animals, gave an emphasis to their toxic and antinutrient effects. Subsequent studies in tropical ruminants and wild herbivores have highlighted the high levels than can occur in some diets and the extensive microbial modification and degradation that can occur in the tract. This paper reviews aspects of plant phenolics as they relate to ruminant nutrition in tropical or semi-arid environments in which some forage plants contain high levels of phenolic compounds. Effects range from occasional acute toxicity of hydrolysable tannins, to acetate-releasing microbial degradations that apparently enable certain phenolics to act as nutrients. The most important and complex effects are those due to tannin-protein interactions. Although these can clearly reduce feed intake, nutrient digestibilities, and protein availability, many of the interactions are still not understood. The diverse effects of plant phenolics on nutrient flow probably result from the balance between adverse effects on some organisms and the rate at which they are degraded or inactivated by other organisms, and improved animal performance can likely be obtained by manipulation of rumen microbial metabolism.
The secretion of gonadotrophins, insulin and insulin-like growth factor 1 by Merino rams supplemented with different legume seeds
Authors: Blache D , Miller DW , Milton JTB , Martin GB
Published: November 2004

Supplementing mature rams with lupin seed (Lupinus angustifolius, a highly digestible source of energy and protein) increases gonadotrophin secretion within 5-10 days. When sheep receive a post-ruminal supplement of protein and energy equivalent to that in the lupin supplement, LH secretion is increased but not to the same extent as with lupin seed itself. This suggests that lupin seed contains a specific mixture of nutrients or an unknown component that exerts effects on the brain centres that control gonadotrophin secretion. This hypothesis was tested by comparing the responses to isonitrogenous and isoenergetic supplements of 3 legumes: lupins, cowpeas, and soybeans. Rams were fed the supplements for 10 days and blood was sampled every 20 min for 24 h on days -1, 5, and 10 relative to the start of supplementation. The plasma was assayed for LH, FSH, and the metabolic hormones insulin and insulin-like growth factor 1 (IGF-1). Both the cowpea and the lupin supplements increased LH pulse frequency and the mean concentrations of insulin and IGF-1 on days 5 and 10 compared with day -1 (P < 0.05). The soybean supplement did not affect LH pulse frequency or the concentrations of insulin or IGF-1. Only the cowpea supplement increased the mean concentration of FSH. The nutritional stimulation of the reproductive centres of the brain appears not to be specific to lupins, because the diet supplemented with cowpeas evoked similar responses. The lack of response to soybean seed suggests that the effects of diet on secretion of metabolic and gonadotrophic hormones are not due simply to the total energy and protein content of the diets, but to subtle differences in their chemical constituents.
Variation within Stylosanthes sp. aff. scabra and comparison with its closest allies, S. scabra and S. hamata
Authors: Jansen PI , Edye LA
Published: November 2004

Forty Stylosanthes scabra, S. hamata, and S. sp. aff. scabra lines were grown at CSIRO Lansdown Research Station, North Queensland. Morphological features were grouped with the numerical classification program PATN. Agronomical attributes were recorded and analysed for each group. The resulting 5 groups were largely homogeneous by species. Seed colour, the presence of leaf bristles and stipule horn lateral bristles, stem and inflorescence viscidity, growth habit, and stem length and thickness were important features separating the groups. There were significant differences in yield and seed yield between the groups. Hardseededness ranged from 2 to 79% and the low level of hardseededness in many high-yielding lines is cause for concern. Stylosanthes sp. aff. scabra was found to differ from S. scabra in its narrower and hairless leaves and the presence of stipule horn lateral bristles in combination with a very short or an absent stipule horn terminal bristle. Apart from 1 line, the S. sp. aff. scabra lines fell within 2 groups: a prostrate, low-yielding, anthracnose-susceptible group; and an erect, high-yielding, anthracnose-resistant group. Lines from the second group will be released for commercial use.
Development and density of wool follicles in Merino sheep selected for single fibre characteristics
Authors: Moore GPM , Jackson N , Isaacs K , Brown G
Published: November 2004

Wool follicles are classified into 3 major types: primary (P), original secondary (SO), and derived secondary (SD). They are formed during fetal life as successive waves of initiation pass through the skin. P follicles are the first to be initiated. SO follicles develop between the primaries and are separated from them at non-randomly distributed sites. SD follicles are the last to be initiated and branch from SO and other SD follicles. We have measured the densities of these follicles in 4 lines of sheep selected for different fleece characters. Primary follicle and total follicle densities (NP and NP + NS) were estimated by conventional procedures. The densities of pilary canals were also obtained to provide a measure of Np + NSO. Follicle counts in both adult and fetal animals showed that NP and NP + NSO were relatively constant across the lines. Predominantly, density differences were due to variations in the numbers of follicles initiated during the last wave, forming the derived secondary population. Changes in follicle densities were therefore effected by developmental mechanisms that increase or decrease the extent of branching rather than by altering the numbers of P and SO follicles. The results suggest firstly that the numbers of initiation sites for P or SO follicle formation in the fetus, corresponding to the pilary canals of adult skin, are limited. Secondly, the skin has the capacity to continue to initiate follicles after most or all of the sites have been occupied. It is concluded that the mechanisms controlling follicle initiation site densities and total follicle densities are independently regulated in the sheep. The observations are discussed in relation to factors that influence the densities of the different follicle types. The results have practical implications for changing fleece weight and fibre diameter through selective breeding.
REML estimates of variance and covariance components for production traits in Australian Merino sheep, using an animal model. 1. Body weight from birth to 22 months
Authors: Vaez Torshizi R , Nicolas FW , Raadsma HW
Published: November 2004

Variance components for direct additive genetic, maternal additive genetic, and maternal environmental effects, and the covariance between direct and maternal additive genetic effects, were estimated by restricted maximum likelihood (REML) procedures, using an animal model, for body weight between birth and 22 months of age in Australian Merino sheep. Direct heritability was estimated to be 0.30 for birth weight, 0.28 for weaning weight, 0.24 for body weight at 10 months, 0.34 for body weight at 16 months, and 0.34 for body weight at 22 months. Maternal heritability estimates were 0.29, 0.41, 0.14, 0.07, and 0.07 for the same performances, respectively. Our results suggested that for birth weight and weaning weight, maternal additive genetic effects and the covariance between direct and maternal additive genetic effects were important. Following weaning, maternal additive genetic effects were the only significant maternal effects. Genetic correlations between direct and maternal additive effects were -0.43, -0.59, and -0.29 for birth weight, weaning weight, and body weight at 10 months, respectively. Direct and maternal additive genetic correlations between birth weight and body weight performances at later ages were positive and moderate, ranging from 0.17 to 0.52 and from 0.06 to 0.65, respectively, whereas they were positive and high between weaning weight and later weights, ranging from 0.59 to 0.77 and from 0.61 to 0.85, respectively. A carry-over of maternal influence after weaning was shown. Early (indirect) selection for body weight at weaning or 10 months will achieve a substantial proportion (between 53 and 81%) of direct response for performance at later ages (16 and 22 months).
Trans-bonded pairs of E-cadherin exhibit a remarkable hierarchy of mechanical strengths
Authors: Perret E. , Leung A. , Feracci H. , Evans E.
Published: November 2004

Classical cadherins are primary mediators of calcium-dependent cell interactions in multicellular organisms. Organized in five tandemly repeated E-cadherin (EC) modules, the extracellular segments of these membrane-spanning glycoproteins interact homophilically between opposing cells to create highly regulated patterns of attachment stabilized by cytoskeletal elements inside the cells. Despite many structural and functional studies, a significant controversy exists in regard to the organization of cadherin binding in adhesion sites. Supported by considerable evidence, perhaps the most widely held view is that opposing N-terminal EC1–EC2 (EC12) domains form a “zipper” of bonds. However, immobilized on two atomically smooth surfaces and pushed to adhesive contact, opposing cadherins become fully interdigitated and unbind through three discrete jumps comparable with domain dimensions when pulled apart. So the question remains as to whether mechanical adhesion strength emanates solely from interactions between the peripheral N-terminal domains or involves multiple overlapping domains. It is also unclear whether a primary adhesion complex is formed by a single opposing pair of cadherins or whether the complex involves a more complicated network of cis-bonded multimers. To address these questions, we used a special jump/ramp mode of force spectroscopy to test isolated pairwise interactions between recombinant fragments of ECs. Besides the formation of strong trans-bonded dimers, we find a remarkable hierarchy of rupture strengths for bonds between the full five-domain fragments that suggests multiple mechanical functions for cadherins, perhaps providing distinct properties needed for transient-specific recognition as well as stable tissue formation.
Araceae from the Early Cretaceous of Portugal: Evidence on the emergence of monocotyledons
Authors: Friis Else Marie , Pedersen Kaj Raunsgaard , Crane Peter R.
Published: November 2004

A new species (
Mayoa portugallica
genus novum species novum) of highly characteristic inaperturate, striate fossil pollen is described from the Early Cretaceous (Barremian–Aptian) of Torres Vedras in the Western Portuguese Basin. Based on comparison with extant taxa,
Mayoa
is assigned to the tribe Spathiphylleae (subfamily Monsteroideae) of the extant monocotyledonous family Araceae. Recognition of Araceae in the Early Cretaceous is consistent with the position of this family and other Alismatales as the sister group to all other monocots except
Acorus
. The early occurrence is also consistent with the position of Spathiphylleae with respect to the bulk of aroid diversity.
Mayoa
occurs in the earliest fossil floras (from circa 110 to 120 million years ago) that contain angiosperm flowers, carpels, and stamens. The new fossil provides unequivocal evidence of monocots in early angiosperm assemblages that also include a variety of key “magnoliid” lineages (e.g., Chloranthaceae) but only a limited diversity of eudicots.
Solving and analyzing side-chain positioning problems using linear and integer programming
Authors: Kingsford Carleton L. , Chazelle Bernard , Singh Mona
Published: November 2004

Motivation: Side-chain positioning is a central component of homology modeling and protein design. In a common formulation of the problem, the backbone is fixed, side-chain conformations come from a rotamer library, and a pairwise energy function is optimized. It is NP-complete to find even a reasonable approximate solution to this problem. We seek to put this hardness result into practical context.

Results: We present an integer linear programming (ILP) formulation of side-chain positioning that allows us to tackle large problem sizes. We relax the integrality constraint to give a polynomial-time linear programming (LP) heuristic. We apply LP to position side chains on native and homologous backbones and to choose side chains for protein design. Surprisingly, when positioning side chains on native and homologous backbones, optimal solutions using a simple, biologically relevant energy function can usually be found using LP. On the other hand, the design problem often cannot be solved using LP directly; however, optimal solutions for large instances can still be found using the computationally more expensive ILP procedure. While different energy functions also affect the difficulty of the problem, the LP/ILP approach is able to find optimal solutions. Our analysis is the first large-scale demonstration that LP-based approaches are highly effective in finding optimal (and successive near-optimal) solutions for the side-chain positioning problem.

Availability: The source code for generating the ILP given a file of pairwise energies between rotamers is available online at http://compbio.cs.princeton.edu/scplp

Contact:  msingh@cs.princeton.edu
Defining maritime boundaries: ‘the murky hand of history's oversight’ in the Gulf of Maine
Authors: Marshall Joan
Published: November 2004

In this paper, an unresolved boundary dispute in the Gulf of Maine, between the United States and Canada, in an area known as the Grey Zone is examined. In the context of a juridically weak framework of principles for determining international maritime boundaries, the case of a small fishing community caught between conflicting national interests and a lucrative fishing zone being claimed by both countries is examined. Left unresolved with the 1984 International Court of Justice decision defining the ‘Hague Line’, this dispute is made more problematic because of ambiguous objectives and conflicting agendas between national governments, between state and community levels and within the community itself.
Municipally managed gentrification in South Parkdale, Toronto
Authors: Slater Tom
Published: November 2004

Earlier studies of Canadian inner‐city gentrification, especially in Toronto, project an image of the process as being emancipatory: a middle‐class reaction to the oppressive conformity of suburbia, modernist planning and market principles. This paper, a case study of gentrification in South Parkdale, Toronto, questions this image by illustrating the role of local context in theory and policy and the consequences of gentrification for vulnerable inner‐city populations. Once a desirable residential neighbourhood, South Parkdale experienced disinvestment following the construction of the Gardiner Expressway in the 1960s and also experienced further problems in the 1970s and 1980s following the deinstitution‐alisation of psychiatric patients from adjacent hospitals. Discharged patients suffered from a shortage of affordable housing options, and many ended up in substandard rooming houses and bachelorettes, of which South Parkdale has a disproportionate share in Toronto. The neighbourhood's sporadic gentrification since the mid‐1980s has intensified in recent years, as the City of Toronto is regularising and licensing the neighbourhood's low‐income housing—a major concern for tenants who fear that landlords will use recent provincial legislation on tenancy to attract wealthier residents into their improved buildings. This paper examines this situation with qualitative evidence and argues that gentrification in South Parkdale, driven and managed by neoliberal policy, is far from an emancipatory process and argues for an interpretation of gentrification that looks beyond the experiences of the middle classes.
The distribution and morphometry of lakes and reservoirs in British Columbia: a provincial inventory
Authors: Schiefer Erik , Klinkenberg Brian
Published: November 2004

An inventory of provincial lakes and reservoirs has been developed to characterise and assess the distribution and morphometry of standing water bodies in British Columbia. In the province, there are over 241,500 lakes and reservoirs greater than 1,000 m

2

in size. These water bodies cover 2.37 percent of the province area and contain an estimated 521 km

3

of water (312 km

3

in natural lakes and 209 km

3

in reservoirs). A hypsometric relation suitable for order‐of‐magnitude estimates of lake volume from lake area is presented. Based on the distribution and morphometric attributes of lakes, several distinctive limnologic regions were identified, including the northeastern Alberta Plateau (highest proportion of circular lakes), the southwestern Alberta Plateau (lowest lake density/coverage and highest proportion of irregularly shaped lakes) and the Milbanke Strandflat (highest density of lakes). Observed regional and scale‐related patterns in lake distribution/morphometry appear to be largely related to geomorphic controls, particularly tectonic and glacial history. Large‐scale hydrologic implications of these standing water bodies and potential ecosystem/water resource management applications of the provincial inventory are also discussed.