bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of growth hormone-releasing factors and cottonseed meal on hormones and metabolites in plasma from lambs fed lucerne chaff ad libitum
Authors: Sainz RD , Hosking BJ , Hart FJ , Spencer GSG
Published: November 2004

This study was part of an experiment on the effects of cottonseed meal (CSM) and growth hormone-releasing factor (GRF) on growth in lambs fed lucerne chaff. Forty-eight crossbred lambs were fed lucerne chaff ad libitum, alone or with a cottonseed meal supplement (CSM; 300 g/day). Eight lambs from each group were injected twice daily with recombinant or synthetic GRF (rGRF and sGRF respectively; 30 8g per kg body weight/day) or excipient only for 28 or 30 days. Jugular blood samples were obtained on days 0, 7, 14, 21 and 28. On day 29, blood samples were taken from selected lambs (n = 2/group) at 0, 20, 40, 60, 80, 100, 120, 160 and 240 min after injection. Supplementation of lucerne chaff with CSM generally increased glucose and urea concentrations in plasma, reflecting improved energy and protein status. However, concentrations of growth hormone, insulin-like growth factor-1 and insulin were unaffected by CSM, as were plasma proteins, triacylglycerols and non-esterified fatty acids. Injection of rGRF and sGRF stimulated secretion of growth hormone (GH), insulin-like growth factor-1 (IGF-1) and insulin. Peak GH concentrations (20 min) following injection of GRF appeared to be higher in lambs fed CSM than in those receiving lucerne chaff alone. In contrast, maximal concentrations of IGF-1 were seen after 14 days of treatment. These changes were accompanied by increased plasma glucose, with no changes in triacylglycerols, non-esterified fatty acids and protein. Plasma urea was reduced by GRF, indicating that amino acids were diverted away from catabolism towards protein synthesis. These two sources of GRF were very similar in their endocrine and metabolic effects. This confirms similar observations regarding their effects on growth performance and carcass composition.
The effects of sustained exercise on gluconeogenesis, glycogenolysis and glycogen synthesis in Merino sheep
Authors: Harman NG , Pethick DW
Published: November 2004

The ability of sheep to maintain an elevated rate of glucose metabolism in the splanchnic tissues and skeletal muscle during long-term exercise was studied using isotope dilution and arteriovenous difference techniques. Comparisons were made between Merino ewes at rest or walking at 4.5 km h-1 on a 0' incline (30% VO2max) for 4 h or 9� incline (60% VO2max.) for 2 h. Sheep were close to exhaustion at the completion of the later rate of exercise. Exercise elicited an initial hyperglycemia with a return to euglycemia at the end of exercise. The entry rate of glucose increased 2-6 and 3.4 times during exercise at 30 and 60% VO2max respectively. Similar increases in the rate of glucose release by the liver, were seen; the increases were maintained throughout the exercise period. Assuming complete conversion of gluconeogenic substrates extracted by the liver gluconeogenesis could have accounted for 90% and 60% of the glucose release during exercise at 30% and 60% VO2max. Hepatic glycogenolysis was also substantial, and when summed with gluconeogenesis 120-150% of the glucose release was accounted for. The ability of sheep to replace glycogen depleted owing to exercise was significant in liver and type IIA muscle (m. semimembranosis) and represented rates 3-6 times those previously reported in sheep and cattle. Providing sheep do not suffer hyperthermia, they are well equipped to endure long periods of exercise owing to an ability to maintain carbohydrate balance.
Nitrogen cycling in a semi-arid Mediterranean region: changes in soil N and organic matter under several crop/livestock production systems
Authors: White PF , Nersoyan NK , Christiansen S
Published: November 2004

There is a need to quantify the effects on soil N of introducing different legumes into the farming systems of West Asia and North Africa. This paper presents 6 years results from an on-going experiment aimed at examining the productivity of several crop/livestock farming systems in north west Syria. Changes in total soil N and organic matter when either medic pasture (3 stocking rates), vetch, lentil, fallow or watermelon were rotated yearly with wheat were examined. In addition, in the sixth year of the experiment, mineral N levels in the soil and the N content of the wheat and legumes shoots were determined in order to formulate a simple N balance for each rotation. Medic pasture and vetch rotations increased total soil N and the organic matter content of the soil. Lentil had no effect on total soil N or the organic matter content. Total soil N also remained constant in the fallow rotation, but organic matter content of the soil tended to decrease. The changes in soil properties had implications for the long term production from the different rotations, and highlighted the importance of retaining legume residues for maintaining fertility.
Integrated management of canegrubs in Australia: current situation and future research directions
Authors: Robertson LN , Allsopp PG , Chandler KJ , Mullins RT
Published: November 2004

Nineteen species of scarab larvae, collectively known as canegrubs, attack the root system of sugarcane in Australia. Thousands of hectares of sugarcane were damaged before the introduction of organochlorine insecticides in 1948. A controlled-release formulation of chlorpyrifos (suSCon Blue) and a non-residual formulation of ethoprophos (Mocap) replaced the organochlorines in the 1980s. Recent failures of both these products in some fields have intensified the search for alternative controls. This review covers the current knowledge of canegrub biology, ecology and control in Australia. An outline of research required to develop sustainable pest management for canegrubs is given. Knowledge of the population dynamics of canegrubs will be integrated with cultural, chemical and biological controls as appropriate for each pest in each region. A decision-support system will help pest managers to make appropriate choices.
Characterization of a unique population of Fusarium oxysporum f.sp. cubense causing Fusarium wilt in Cavendish bananas at Carnarvon, Western Australia
Authors: Pegg KG , Shivas RG , Moore NY , Bentley S
Published: November 2004

A unique population of Fusarium oxysporum f. sp. cubense affecting Cavendish cv. Williams banana plants was characterized using vegetative compatibility, volatile production, RAPD-PCR analysis, pectic enzyme production and pathogenicity. The isolates were more like race 1 isolates than race 4 isolates, although they were capable of attacking Cavendish clones. The Carnarvon isolates did not belong to any of the vegetative compatibility groups (VCGs) known to occur in Australia or overseas; they belonged in the 'inodoraturn' volatile group; they had 29% genetic similarity to race 4 isolates and 76% similarity to race 1 isolates based on RAPD-PCR banding patterns; they belonged in the same pectic zymogram group as race 1 isolates and were virulent on 3-month-old Cavendish cv. Williams, Gros Michel and Pisang Gajih Merah plants in glasshouse tests.
Some investigations into soil and vegetation relationships associated with alkaline-saline soil surfaces in the Walcha area, Northern Tablelands, New South Wales
Authors: Kreeb KH , Whalley RDB , Charley JL
Published: November 2004

The characteristics of the soil, vegetation and groundwater at a dryland salinity site on Miramoona, a property near Walcha on the Northern Tablelands of New South Wales, were investigated. Soil parameters measured at 23 points along a 200 m transect were highly correlated with the pattern of vegetation. Of overriding significance was soil pH, which varied from a high of over 10 on bare areas delineated by Critesion marinum and Cynodon dactylon to a low of less than 5 on grazing land supporting the growth of a wide range of pasture species. The bare areas were characterized by alkalinity. While they were sodic at all depths measured, they were only marginally saline and then only at the soil surface. The chemical composition of the groundwater collected from three piezometer tubes varied quite markedly over the site. It is hypothesized that the presence of alkaline bare areas on the Northern Tablelands is not a new problem, but rather the natural result of alternating wet and dry periods which have induced accumulation of carbonates and bicarbonates of the alkali cations, notably sodium. Drainage of the original perched swamps by the early landholders, tree clearing and the grazing of domestic livestock would have accelerated the process since European settlement. However, tree planting would appear unlikely to have any impact on the reclamation process in the short term. A more viable option would be the recreation of the original swamps in suitable situations, although this solution would create problems for grazing management.
Nitrogen fixation in chickpea. II. Comparison of 15N enrichment and 15N natural abundance methods for estimating nitrogen fixation
Authors: Doughton JA , Saffigna PG , Vallis I , Mayer RJ
Published: November 2004

The 15N enrichment and 15N natural abundance methods for estimating N2 fixation in chickpea were compared over a range of soil NO3-N levels at crop establishment varying from 10 to 326 kg N/ha (0-120 cm depth). Barley was used as a non-N2 fixing control crop. Both methods estimated reduced N2 fixation as soil NO3-N levels at crop establishment increased. Similar estimates of % N2 fixation were obtained at high values, but at low values the enrichment method gave lower estimates, some of which were negative. The 15N natural abundance method provided realistic estimates of % N2 fixation across all soil N03-N levels at crop establishment. An asymptotic curve described a close ( R2 = 0.95) relationship between these factors. Standard errors of estimates of means for the 15N natural abundance method remained acceptable and relatively stable over the full range of measurements; however, with the 15N enrichment method they became unacceptably large at low values of % N2 fixation. These large errors may have been partly due to legume and control plants assimilating mineral N of differing 15N enrichment. High mineral N levels associated with low values of % N2 fixation were also shown to reduce reliability of N2 fixation values estimated by the 15N enrichment method. These errors caused potentially greater inaccuracy at low values of % N2 fixation than at high values. To compare N2 fixation means statistically, transformations were necessary to stabilize variance and to impart lower weightings to plots with low values of % N2 fixation.
Control of buffalo fly (Haematobia irritans exigua de Meijere) on dairy and beef cattle using traps
Authors: Sutherst RW , Tozer RS
Published: November 2004

The design and testing of traps are described for control of the buffalo fly Haematobia irritans exigua on dairy and beef cattle in Australia. The initial design, for use on milking cows, consisted of a translucent, plastic-covered tunnel, with compartments separated by plastic partitions and doorways with black shade-cloth curtains. The curtains brushed flies off the cattle as they passed through the tunnel. The flies were attracted to the light and ascended the walls to be confined in the dome-shaped roof. The traps removed 80% of the flies each time the cattle passed through them. During farm trials in 1990-91, fly numbers (8) on milking cows were reduced by 85% compared with those (94) on other cattle on the same farm, and by 65% compared with neighbouring milking cows (30), which received an average of three pesticide treatments. Breeding of buffalo fly was reduced by 81% on the pastures grazed by milking cattle using the traps. In 1992 and 1993, a smaller portable trap was developed for use by all types of cattle. Replacement of the shade-cloth curtains with brushes and addition of a translucent false ceiling increased the efficiency of the trap from 80 to 90%. The traps achieved 90% control on five dairy and two beef properties compared with cattle given traditional pesticide treatments. The results demonstrate the feasibility of controlling Haematobia without insecticides, by using a simple, sustainable and environmentally friendly trap, provided that cattle use the traps regularly.
Virginiamycin to protect sheep fed wheat, barley or oats from grain poisoning under simulated drought feeding conditions
Authors: Godfrey SI , Rowe JB , Thorniley GR , Boyce MD , Speijers EJ
Published: November 2004

Lactic acidosis can occur when large amounts of cereal grains are given to sheep without adequate adaptation. Virginiamycin has been shown to reduce lactic acid accumulation in vitro and in the rumen of sheep following ingestion of readily fermentable carbohydrates. The aim of this experiment was to determine if virginiamycin would prevent acidosis in hungry sheep given wheat, barley or oat grain without any adaptation. Merino wethers, penned individually and given wheat chaff 300 g/day for 9 days, were offered 2.1 kg of wheat, barley or oat grain, with or without virginiamycin. Rumen fluid was collected before and 6 and 24 h after grain feeding. Blood samples were obtained before and 24 and 48 h after grain feeding. 24 h after grain feeding, rumen pH was lower (P0.001) and rumen L-lactate higher (P0.05) in sheep given wheat without than with virginiamycin. D- and L-lactate were produced in equal proportions in sheep given grain plus virginiamycin, while sheep fed on grain without virginiamycin produced more of the L-lactate isomer 24 h after grain feeding. There was no effect of virginiamycin on grain intake, although intake of sheep given oat grain was lower (P0.01) than intake of sheep given wheat or barley. The number of sheep withdrawn from the experiment after grain feeding was lower (P0.05) when wheat was given to sheep with virginiamycin compared with untreated wheat grain. Feeding virginiamycin with grain did not reduce grain intake, but reduced the severity of acidosis in sheep given wheat grain.
Na/K ratios as the basis of salt tolerance in wheat
Authors: Chhipa BR , Lal P
Published: November 2004

Na/K ratios of salt tolerant and susceptible varieties of wheat were measured. The Na/K ratio in wheat grain and straw above or below a particular level indicate the tolerance of wheat to salinity. This fact was confirmed by applying presoaking treatments of plant hormones to test susceptibility of varieties. On the basis of the results obtained in two pot experiments, the limit of the Na/K ratio of grain and straw of wheat for designating a variety as tolerant is <0.15 and <0.4 respectively, while this ratio at, the tillering stage is 0.5.
Interactions between three species of mushroom cecids (Diptera: Cecidomyiidae) and three hybrid strains of the cultivated mushroom Agaricus bisporus
Authors: Clift AD , Terras MA
Published: November 2004

The effect of three species of paedogenetic cecidomyiid larvae, at two infestation times, on the yields of three hybrid Agaricus bisporus strains is reported. The densities of larvae that developed, time of larval swarming and rates of pupation were recorded. Mycophila barnesi was the most damaging species, followed by Heteropeza pygmaea and Henria psalliotae. Time of infestation was important, with earlier infestations of all species more damaging, both in direct yield loss and by larvae contaminating sporophores. The hybrid strains also responded differently, with the U3 hybrid most susceptible, followed by U1 and the Intermediate hybrid. The exception was M. barnesi infesting the Intermediate hybrid at spawning, contaminating over 90% of the sporophores.
Opportunistic association between Pythium species and weed residues causing seedling emergence failure in cereals
Authors: Pittaway PA
Published: November 2004

Field trials were conducted to establish the link between weed residue management, Pythium infectivity and cereal seedling emergence failure. The herbicide glyphosate was used to manage weed-free and weed residue treatments, and the systemic fungicide metalaxyl was used to protect seedlings from pythiaceous attack. Seedling vigour and emergence were enhanced by the application of metalaxyl, and by the total suppression of weed growth. Invasion of cereal seedlings by pythiaceous fungi was greatest when seed was sown into cloddy seedbeds within 1-3 days after herbicide application. Debilitated weeds enhanced the activity of pythiaceous pathogens, promoting the invasion of cereals sown into the residues. If sowing is delayed for 3 weeks after herbicide application, pythiaceous activity will be reduced by saprophytic competitors colonizing the residues, resulting in improved seedling vigour and establishment.
The influence of temperature, inoculum level and race of Fusarium oxysporum f.sp. cubense on the disease reaction of banana cv. Cavendish
Authors: Brake VM , Pegg KG , Irwin JAG , Chaseling J
Published: November 2004

Cavendish banana plants were grown in soil infested with different levels of microconidia of races 1 and 4 of Fusarium oxyspomm Schlect. f. sp. cubense (E.F. Smith) Snyd. & Hans. The 4-week-old plants were incubated at 20� and 28�C in temperature controlled cabinets subject to natural light fluctuations. Race 1, which does not normally infect Cavendish in the field, infected the plants at both temperatures, as did race 4. Results indicated that temperature was primarily affecting plant growth rather than influencing the aggressiveness of the pathogen. Inoculum levels were also found to influence disease severity with a minimum of 4.5 x l04 microconidia/g dry weight of soil required before macroscopic symptoms were observed. The suitability of month-old tissue culture derived plants for screening for resistance and the evolution of the Cavendish attacking race 4 strains are discussed in the light of these findings.
Corrigendum - Leaf area development in barley—model construction and response to soil moisture status
Authors: Milroy SP , Goyne PJ
Published: November 2004

A model to simulate leaf area development for barley at the whole plant level was constructed. Data for leaf area development in the absence of soil water stress were collected from irrigated field trials grown at Hermitage Research Station, near Warwick, Queensland, in 1990. The response of leaf area expansion to soil water status was measured in a glasshouse trial. In the model, green leaf area per plant (GPLA) is derived as the difference between total leaf area produced per plant (TPLA) and senesced leaf area (SPLA). TPLA and SPLA are described by logistic functions of thermal time. Two types of senescence are included: that due to ageing of the whole plant (ontogenetic senescence) and senescence associated with the development of large canopies (light-induced senescence). The onset of ontogenetic senescence is linked to anthesis, whereas light-induced senescence occurs if the leaf area index of the crop exceeds 5.5. Leaf expansion of plants in pots varying in the fraction of transpirable soil water available (FTSW) was compared with leaf expansion of those in well-watered pots three times per week. The relationship between relative leaf expansion (RLE) and FTSW was described by a logistic function (r2 = 0.96). A 50% reduction in RLE occurred when FTSW = 0.34. Similarly, a logistic function described the relationship between relative transpiration (RT) and FTSW (r2 = 0.96). A 50% reduction in RT occurred when FTSW = 0.17. Potential leaf expansion as predicted by the non-stressed model was reduced in response to moisture stress via a ramp function relating RLE to RT. The model gave an unbiased prediction of the leaf area dynamics for 21 rainfed and irrigated crops of barley grown in southern Queensland between 1986 and 1993 (RMSD = 1.09 m2 m-2, r2 = 0.75, n = 76). Precision may have been reduced by the lack of information available on parameters for soil water balance when barley is grown on a range of soil types.
Studies on water damage in mungbean. I. Effect of weathering on seed quality and viability
Authors: Williams RW , Lawn RJ , Imrie BC , Byth DE
Published: November 2004

The expansion of mungbean production in Australia is severely limited by the susceptibility of current cultivars to weather damage in the field. The aim of this research was to describe the causes, process, and effects of weathering in mungbean as the first step toward the breeding of resistant cultivars. Symptoms of weather damage were produced by exposing plants to simulated rainfall/high humidity and by subjecting seeds to cycles of wetting and drying. In both cases, symptoms progressed from discolouration, wrinkling, and cracking of the testa, to germination of the seed. Symptoms produced in controlled experiments were the same as those observed in the field. Only seeds that imbibed during the wetting phase developed symptoms of weather damage on drying. Exposure to one cycle of weathering also advanced the timing and degree of damage to seeds during subsequent cycles. This was associated with an increased rate of water absorption in weathered seeds. The lowering of apparent resistance to weather damage with prior exposure to rainfall suggested that only protected material be screened for weathering resistance. The death of seeds remained the ultimate expression of the changes induced by weathering.
Studies on water damage in mungbean. II. Electrical conductivity of seed leachate as an assay of level of damage
Authors: Williams RW , Lawn RJ , Imrie BC , Byth DE
Published: November 2004

Weather-damaged seeds of mungbean are unsuitable for the production of bean sprouts and some other food uses. The breeding of resistant cultivars requires an understanding of the weathering process and the use of suitable criteria for measuring the degree of weather damage. The aim of this research was to describe the effect of weathering on the electrical conductivity of leachate from exposed seeds and to evaluate this technique as a means of discriminating among levels of weather damage. Seeds were weathered in the field or immersed in water in the laboratory for varying durations during one or more cycles of wetting and drying. Leachate conductivities generally increased with increasing visual damage and decreasing viability of seeds. When measurements of conductivity were delayed, the results appeared to be confounded by the extent to which solutes were lost during previous exposure/s to weathering. Measurements soon after immersion tended to reduce this effect and to better reflect the level of weather damage in seeds of mungbean. It was concluded that leachate conductivity technique can provide a reliable assay of weather damage in mungbean. When seeds have been exposed to severe weathering, however, the relationship breaks down, and the technique can give misleading results.
Survival of Colletotrichum gloeosporioides on Stylosanthes scabra cv. Fitzroy during the dry season
Authors: Boland RM , Chakraborty S , Irwin JAG
Published: November 2004

Infected stems of the tropical pasture legume Stylosanthes scabra cv. Fitzroy were assessed over two consecutive dry seasons to determine if Colletotrichum gloeosporioides survived as conidia on lesions formed during the previous wet season or as hyphae within infected tissue. In the second season, infected stem pieces placed on the soil surface (debris) and in a 15�C incubator at the beginning of the dry season were assessed in addition to the material from living plants. Infective conidia were present in sufficient numbers to be detected in all but the initial sample in each season, and C. gloeosporioides could be isolated from lesions on plant tissue throughout both dry seasons. Conidium density on live stems was variable in the first season, where no rain fell until the onset of the wet season in mid-November. Conidia were present in similar densities on stems throughout the second dry season, when intermittent light rain fell during the assessment period. The mean density of conidia was significantly higher on live stems than on debris or stems stored at 15�C. Large numbers of conidia were produced on stem pieces from living plants and debris after incubation under conditions conducive to sporulation. Conidia were, therefore, present or could be rapidly produced to initiate an epidemic once favourable conditions for dispersal and infection occurred.
Biserrula pelecinus L.-a legume pasture species with potential for acid, duplex soils which is nodulated by unique root-nodule bacteria
Authors: Howieson JG , Loi A , Carr SJ
Published: November 2004

Biserrula pelecinus is a monotypic genus which displays agronomic potential for acid, duplex soils. Whilst it is widespread in the Mediterranean basin, it represents a new pasture legume to Australia. The root-nodule bacteria isolated from B. pelecinus nodules collected from Morocco and Sardinia were unique in the sense that they appeared to be specific to this legume. They also grew at a lower pH on an acidified growth medium than the rhizobia for clover, peas and medic, which indicated a potential adaptation to acid soils. B. pelecinus was not nodulated by any of the commercially available species of root-nodule bacteria in use in Australia that we evaluated. Hence, it appears that the development of B. pelecinus for industry will be contingent upon the commercialization of its specific rhizobia. Several genotypes of B. pelecinus produced vigorous growth and high seed yields at two field sites in the wheatbelt of Western Australia, which received less than 250 mm rainfall in 1994.
Estimates of genetic parameters and breeding values for New Zealand and Australian Angus cattle
Authors: Meyer K
Published: November 2004

Genetic parameters and adjustment factors for birth, weaning, yearling and final weight were estimated for the New Zealand Angus population, fitting an animal model including maternal genetic and permanent environmental effects as additional random effects. Overall, pooled covariance matrices agreed well with those for Australian Angus, though heritability estimates for birth weight were somewhat lower than in Australian Angus. BREEDPLAN estimates of breeding values and their accuracies were obtained for each population separately. Correlations between estimates for sires with accurate proofs in both countries agreed with their expectations, giving no indication of a genotype x environment interaction. A joint genetic evaluation using adjustment factors specific to each country but the same covariance matrices is recommended.
Evaluation of Angus, Charolais and Hereford as terminal sire breeds on Hereford and first-cross cows. II. Carcase characteristics and retail yield of progeny
Authors: Arthur PF , Hearnshaw H , Johnston D , Stephenson PD
Published: November 2004

The characteristics and retail yield of carcases of 482 Angus, Charolais and Hereford sired progeny out of straightbred Hereford (HxH), and first-cross Brahman x Hereford (BxH), Simmental x Hereford (SxH) and Friesian x Hereford (FxH) dams were evaluated. The cattle had been raised and slaughtered for either the vealer (both sexes), yearling domestic (both sexes) or the heavy export steer market. The data were analysed within market type, and at a constant age at slaughter (281, 478 and 829 days for vealer, yearling domestic and heavy export carcases respectively) and also at a constant hot P8 fat depth (4.6, 7.8 and 14.9 mm for the three markets respectively) and constant hot carcase weight (160, 200 and 343 kg for the three markets respectively). At a constant age, carcases of Charolais sired progeny were significantly (P < 0.05) heavier (8-16%, depending on market type), leaner, had larger eye muscle area and higher dressing percentage than those of Angus and Hereford sired progeny. This resulted in 12 to 17% (P < 0.05) more kg of boneless saleable meat (retail yield) from carcasses of Charolais sired progeny. At a constant hot P8 fat depth, the magnitude of the sire breed differences increased, whereas at a constant hot carcase weight, the differences became non-significant or were reduced in magnitude. At a constant age, progeny of BxH dams had higher ( P < 0.05) dressing percentage than those of the other dam breeds for all market types except the vealer market. Progeny of FxH dams had more (P < 0.05) channel and kidney fat than those of the other dam breeds, even at a constant hot P8 fat depth. Retail yield, as a percentage of the boned side, was highest for carcases of progeny of BxH dams and lowest for those of progeny of FxH dams (70.2% and 70.3% v. 69.1% and 69.2%, for vealer and yearling domestic carcases respectively, at a constant age). Sire and dam breed effects for the individual primal cuts, as percentages of the boned side, were not significant for most of the primal cuts, and where significant, the differences were very small.
The lipid composition of cashmere goat fleece
Authors: Hillbrick GC , Tucker DJ , Smith GC
Published: November 2004

This study examined the differences in the chemical composition of the lipid extracted from the fleeces of intact and gonadectomized Australian cashmere goats (Capra hircus laniger). Lipid was extracted with either petroleum ether or chloroform/methanol, and analysed by gas chromatography and gas chromatography/mass spectrometry. A large number of buck specific fatty acids (29), which could be potential pheromones, were identified or tentatively identified. The fatty acid composition of buck fleece lipid is more complex than previously reported.
Seasonal changes in systemic hormone profiles and their relationship to patterns of fibre growth and moulting in goats of contrasting genotypes
Authors: Rhind SM , McMillen SR
Published: November 2004

In a 2 x 2 factorial experiment, seasonal changes in hormone and insulin-like growth factor-1 (IGF-1) profiles were compared in goats of two genotypes (Siberian (S) and Icelandic x Scottish feral (IF); n = 20 per genotype) with differing patterns of secondary fibre growth. Half of the goats of each genotype were fed rations containing either 100 or 180 g crude protein (CP)/kg dry matter. The period of secondary fibre growth was longer and the rate of growth greater in S than IF goats, but there were no effects of dietary protein concentration. Mean plasma concentrations of insulin, cortisol, T3 and T4 were higher in winter and those of prolactin, GH and IGF-1 concentrations were higher in summer. Growth of secondary fibre in S goats between January and March was associated with higher plasma prolactin and lower plasma insulin concentrations at this time than in IF goats in which there was no secondary fibre growth. The observed genotypic differences in times of onset and cessation of fibre growth were not associated with differences in the times of seasonal changes in any of the other hormones measured, and there was no effect of dietary protein level on hormone profiles. The higher mean growth rate and greater diameter of secondary fibre in S goats was associated with higher mean concentrations of T4 than in IF goats, throughout the study. Four S goats which exhibited secondary fibre growth during the summer had higher (P < 0.05) mean plasma insulin concentrations than other animals of that genotype. It is suggested that genotypic differences in prolactin concentrations in late winter/spring may affect the time of onset of secondary fibre growth and that the cessation of growth may be influenced by differences in the timing of the seasonal decline of circulating prolactin concentrations to basal levels. However, the maintenance of relatively high plasma insulin concentrations may prolong growth in some circumstances. The higher concentrations of T4 in S than IF goats may have a role in the enhancement of the rate of fibre growth in these animals. The onset of moult in both genotypes was associated with the spring increase in plasma prolactin concentrations.
Animal production under a series of Pinus radiata-pasture agroforestry systems in South-West Victoria, Australia
Authors: Bird PR , Bird PR , Kellas JD , Kellas JD , Kearney GA , Kearney GA , Cumming KN , Cumming KN
Published: November 2004

Liveweight and greasy wool production data from young wethers were collected for the period autumn to early summer for the years 1986 to 1994 from an on-going Pinus radiata-pasture project at Carngham, Victoria. A plantation established in 1981 on a grazing property was thinned in 1983 to give trees spaced at: (i) no trees (a grazing control), (ii) 8 mx 12 m, (iii) 4 mx9 m, (iv) 4 mx3 m in a 5-row belt then a 10-row pasture gap, and (v) 2 mx3 m (original spacing). By 1989 the density of trees in these systems was slightly reduced by windthrow, animal damage and thinning to (ii) 60 trees/ha, (iii) 200 trees/ha wide-spaced, (iv) 200 trees/ha 5-row belt and (v) 1360 trees/ha. All trees in systems (ii), (iii) and (iv) had been pruned to 6 m by late 1992. The sheep stocking policy was initially based on a set 10 sheep ha-1. Since 1991 the stocking rate has been varied yearly in an attempt to maintain similar production per sheep. The pastures were re-sown in 1989 with perennial rye-grass and subterranean clover cultivars. Since 1991, wool production per ha from the 200 trees/ha wide-spaced system has been consistently less than in systems (i), (ii) and (iv). Wool production among systems differed significantly since 1992. Expressed as a percentage of wool production achieved on open pasture, the relative values for the agroforestry systems from 1990 to 1994 as follows.
Nitrogen fixation by irrigated lucerne during the first three years after establishment
Authors: Gault RR , Peoples MB , Turner GL , Lilley DM , Brockwell J , Bergersen FJ
Published: November 2004

Nodulation, N2 fixation (estimated by 15N natural abundance methods) and dry matter production were studied in a lucerne (Medicago sativa) crop managed for hay production at Ginninderra Experiment Station, A.C .T. Measurements were taken in the year of establishment and during two subsequent growing seasons. There were three treatments: (1) no inoculation and no annual fertilizer applied, (2) initial inoculation and superphosphate applied annually, (3) no inoculation, superphosphate applied annually and ammonium sulfate periodically. Before planting and after each growth season, soil was analysed for extractable mineral nitrogen, total nitrogen and the 15N natural abundance of this nitrogen, to the depth explored by lucerne roots. Before planting, no appropriate root-nodule bacteria (Rhizobium meliloti) were detected in the soil and initially plants were nodulated only in the inoculated treatment. Thereafter nodulation increased on the other treatments. Eight months after sowing there were no differences between treatments in numbers of R. meliloti g-l soil or in nodulation. In the third growing season, almost 30 kg ha-1 (dry wt) of nodules were recovered to a depth of 25 cm. These nodules were primarily located on fine, ephemeral roots and many appeared to be renewed after cutting of the lucerne. In the year of establishment, dry matter yields (0% moisture) totalled 3 to 4 t ha-1 in three hay cuts. In succeeding years, total yields were in the range 10 to 13 t ha-1 in four or five cuts per season. Nitrogen removed in the harvested lucerne reached 340 to 410 kg N ha-lyr-l in the second and third years and between 65 and 96% of this N arose from N2 fixation, depending on the method of calculation used. Poorer dry matter production and N2 fixation in treatment 1 in the third growing season was attributed to an insufficient supply of available phosphorus. Fixed N removed in Lucerne hay from treatment 2 totalled at least 640 kg N ha-1 in the three years of the experiment. Also, there were substantial increases in soil nitrogen due to lucerne growth. Although soil compaction made the quantification difficult, at the end of the experiment it was estimated that there was at least an extra 800 kg N ha-1 in the total soil nitrogen under lucerne compared to strips of Phalaris aquatica grown between the lucerne plots. It was concluded that lucerne contributed at least the same amount of fixed nitrogen to the soil as was being removed in the harvested hay.
Stochastic dominance and mean-standard deviation analysis: some critical issues
Authors: Parton KA , Carberry PS
Published: November 2004

Stochastic dominance and mean-standard deviation analysis can be effective procedures for ranking risky alternatives that are expressed in terms of probability distributions of outcomes. However, the conditions applying to their use and their limitations need to be understood. These are set out in the paper, together with an extension that overcomes some constraints to the use of stochastic dominance analysis.
Using a least-squares optimization procedure to estimate botanical composition based on the alkanes of plant cuticular wax
Authors: Dove H , Moore AD
Published: November 2004

The existing mathematical methods for estimating botanical composition of an animal's diet from the concentrations of plant alkanes in herbage and faecal samples all have significant limitations. These include the need for an arbitrary selection of a subset of alkanes for use in the calculations, the loss of information, or the generation of negative estimates for diet components when more than two species are present. We present a new algorithm for solving the diet composition problem, which overcomes these difficulties and is rapid to compute. This algorithm (known as non-negative least squares-NNLS) is shown to perform as well as previous methods on a set of herbage mixtures of known composition. Issues relating to the estimation of the errors of diet composition estimates are discussed.
Probiotic control of lactate accumulation in acutely grain-fed sheep
Authors: Wiryawan KG , Brooker JD
Published: November 2004

When sheep were acutely fed a grain diet, ruminal pH rapidly dropped to less than 5.0, lactic acid exceeded 100 mM and clinical symptoms of acidosis were evident within 24 h. When acute grain feeding was preceeded by inoculation of the rumen with 108 cfu of Selenomonas ruminantium subsp. lactilytica strain JDB201, ruminal lactate was undetectable and ruminal pH was stabilized at 6.3-6.5 for up to 24 h. Inoculation of the rumen with a mixture of 108 cfu each of Selenomonas ruminantium subsp. lactilytica strain JDB201 and Megasphaera elsdenii strain JDB301 was shown to be more effective than Selenomonas ruminantium subsp. lactilytica alone and maintained ruminal stability following acute grain feeding for up to 4 days. A continuous culture model of acidosis was also developed to test the effect of probiotic inoculation in combination with 0.75 8g/mL of Virginiamycin in preventing lactate accumulation and establishing a stable fermentation in vitro. The data suggest that although probiotic treatment is effective, a combination of probiotic and antibiotic may be the best approach to achieve rapid ruminal adaptation during acute grain feeding of sheep.
The effect of a saline and non-saline water table on peach tree water use, growth, productivity and ion uptake
Authors: Boland AM , Jerie PH , Mitchell PD , Irvine JL , Nardella N
Published: November 2004

The effect of salinity and shallow water tables (1.4 m depth) used in combination with Regulated Deficit Irrigation (RDI) on peach trees (Prunus persica, L. Batsch) was studied over 2 years. Under RDI management a non-saline water table contributed up to 30% of water use. A lack of control of vegetative growth in the first season indicated that a shallow water table may interfere with RDI management. A decline in tree health and growth under RDI and a non-saline water table in the following season may have resulted from salinity and/or waterlogging effects. Saline irrigation under RDI management caused an additional decline in tree growth compared with RDI under non-saline conditions, and resulted in a reduction in productivity (yield and fruit size) and increased uptake of sodium (Na) and chloride (Cl) ions in various plant tissues. Similarly, a saline water table caused a decline in tree growth and fruit size in the first season and increased uptake of Na and C1 ions. For all treatments, accumulation of C1 in the leaves, Na and C1 in the fruit, Na in the bark and storage of Na in the butt wood and structural roots was demonstrated. Differences in mechanisms of transport of Na and C1 and the importance of older wood as a storage organ for ions are proposed. The potential for butt wood as a precise indicator of past salinity treatment is suggested. A combination of a shallow water table and moderate salinity environment was shown to present a potential health hazard for peach trees. The need for refinement of RDI management to incorporate leaching in the presence of saline irrigation and/or water tables is proposed. The management of drainage is also essential.
Effect of the environment in which seeds are grown and softened on the incidence of autumn seed softening in two species of annual medics
Authors: Taylor GB
Published: November 2004

The incidence of autumn seed softening, which is believed to offer some protection against false breaks of season, was investigated under a range of environmental conditions in three medic cultivars over three years of softening. Newly ripened pods of burr medic (Medicago polymorpha L.) cvv. Serena and Santiago, and barrel medic (M. truncatula Gaertn.) cv. Cyprus, that were grown at three sites were transferred to four seed softening sites in December. Their progress of seed softening was determined in March, April and June. The seed softening process was also studied in a range of laboratory treatments. Seed growing environments were more important than seed softening environments in determining rates of seed softening in all cultivars. However, the distribution of softening between summer and autumn was generally consistent between the growing and softening environments. More than half the annual softening of Serena and Santiago seeds occurred between the first week of March and June in each of the first three years. A smaller proportion of Cyprus seeds softened between March and June in the first and third years than was the case with the other cultivars. In the first year of softening most of the Serena and Santiago seeds that went on to soften between March and June were already present as latent soft seeds (impermeable seeds that soften rapidly once subjected to appropriate temperature fluctuations) in March, as determined by short-term treatment at 35/10�C. There were fewer latent soft seeds present at this time in later years that responded to this same treatment, suggesting that the longer-term hard seeds had other temperature requirements for the final stage of seed softening. High correlations (r2 = 0.90) were obtained between percent seed softening of the three cultivars in the field in the first year and after laboratory treatment with diurnal temperature fluctuations of 60/15�C for 16 weeks, followed by four diurnal cycles of 35/10�C. Autumn seed softening is sufficiently consistent under a wide range of environmental conditions to be a worthwhile selection criterion in medic improvement programs.
Genetic manipulation of rumen bacteria: from potential to reality
Authors: Gregg K , Allen G , Beard C
Published: November 2004

The development of techniques for manipulating the molecular genetics of bacteria led naturally to suggestions for using this technology to alter rumen function. Despite early difficulties, methods are now available to insert new genetic material into several rumen bacterial species, including Butyrivibrio fibrisolvens, Prevotella ruminicola, and Ruminococcus albus. One strain of B. fibrisolvens has been modified to detoxify a naturally occurring poison that causes major losses of livestock in Australia, Africa, and Central America. The stability of that modified organism has been demonstrated by its recolonization of the rumen and retention of its altered genotype over 5 months in vivo. Many of the persistent doubts about rumen bacterial genetic manipulation and the viability of altered organisms in a competitive environment have been shown to be capable of resolution, and interest in this area of research may be revitalized by these results. Apart from the achievement of specific metabolic improvements, the technology now available will allow extensive characterization of the molecular genetics of rumen bacteria with a precision that was not previously possible.
A comparative study of the in vitro activities of three enzymes - Na+,K+ adenosine triphosphatase, γ -glutamyl transpeptidase, and ornithine decarboxylase - in skin sampled from Merino sheep with different capacities for wool growth
Authors: Williams AJ , Morley FC , Thornberry KJ , Nicol HI
Published: November 2004

The concentration of sodium, potassium adenosine triphosphatase, and the in vitro activities of p-glutamyl transpeptidase and ornithine decarboxylase, were studied in skin from Merino sheep to determine whether these traits differed in skin from sheep whose rate of wool production was influenced by genetic and dietary factors. Sheep from 2 flocks were compared, these being selectively bred for high (Fl+') or low (Fl-') clean fleece weight per head. The sheep were given one of 2 pelleted rations (L and H). The L ration provided metabolisable energy approximately equal to 0.75 times maintenance. The H ration provided approximately twice maintenance, and this ration had a higher protein content due to the inclusion of formaldehyde-protected casein. Eight sheep were studied in each flock at each dietary level. The average concentration of sodium, potassium adenosine triphosphatase, measured by 3H ouabain binding, was 132 pmol/g air-dry skin (s.e.d. = � 30). The activity of p-glutamyl transpeptidase was 0.698mol product/h.mg protein from skin (s.e.d. = � 0.17). The average activity of ornithine decarboxylase in skin was 6.0 8mol carbon dioxide released/h.g skin (s.e.d. � 1.2). Plucking of fibres from the skin 4 h before sampling resulted in an increase (P < 0.05) in the activity of ornithine decarboxylase to 12.9 nmol carbon dioxide1h.g skin. For each of the enzymes, the measured values tended to be greater in the skin of sheep from the genetically high-producing flock and in skin from sheep on the H ration, but none of these differences was statistically significant.