bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of light and temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor
Authors: Ellison PJ , Cullis BR , Kable PF
Published: November 2004

The effect of light on in vitro germination of urediniospores of Tranzschelia discolor was studied over time at different intensitities (up to 400 8E m-2 s-l) within the temperature range 5�C to 20�C. A model was also developed from the data to predict germination at different combinations of light, temperature and times of leaf wetness. Light retarded the germination process, and its effect increased in direct proportion to intensity. At 20�C, for example, the time taken to exceed 80% germination increased from 2 h in the dark to 9 h at 200 8E m-2 s-l. The model showed that there was an interaction between light and temperature, with the effect of light becoming more pronounced as the temperature declined below 20�C. Germination percentages of the order of 90% were, however, recorded within 24 h at all combinations of light intensity and temperature studied. Light also influenced germ tube growth, causing a reduction in the rate of growth. As in germination, its effect increased with increasing light intensity. At 20�C, the average germ tube length at 9 h was 541 8m in the dark, compared with 227 8m at 200 8E m-2 s-1 and 148 8m at 400 8E m-2 s-l. A similar effect was observed at 5�C, where the average germ tube length at 24 h was 274 8m in the dark compared with 157 8m at 200 8E m-2 s-l. The effects of light on the germination and germ tube growth of urediniospores under field conditions are discussed.
Effect of monensin on methane and heat productions of steers fed lucerne hay either ad libitum or at the rate of 250 g/hour
Authors: O'Kelly JC , Spiers WG
Published: November 2004

The effect of monensin supplement (33 mg/kg feed) on methane and heat productions was studied in Brahman steers offered lucerne hay in two feeding regimes: ad libitum (AL) or at the rate of 250 g/h (GPH). The monensin treated animals consumed 65 kg less feed than untreated animals in achieving a mean liveweight gain of.56 kg over 54 days of feeding AL. The 10.5% reduction in daily feed intake due to monensin was associated with a 25.6% reduction in methane production. At equalized feed intakes (adjustments made by covariance) approximately 55% of the reduction in methane caused by monensin was explained by its anorectic effect and 45% by its specific effect on rumen fermentation. In contrast, monensin slightly increased (P = 0.07) liveweight gain, but did not affect methane production in steers fed GPH. Heat production was not significantly altered by the use of monensin in either feeding regime.
The domestication of the native grasses Danthonia richardsonii Cashmore and Danthonia linkii Kunth for agricultural use. I. Selecting for inflorescence seed yield
Authors: Lodge GM
Published: November 2004

Ecotypes of the native grasses Danthonia richardsonii Cashmore and Danthonia linkii Kunth (wallaby grasses) were collected, mostly in northern New South Wales, in 1985-86. All the D. richardsonii plants were 2n = 48 and all the D. linkii plants were 2n = 24. These were grown as spaced plants (1 x l m grid) in a parent nursery at the Agricultural Research Centre, Tamworth, and assessed for seed yield per inflorescence and traits related to seed retention within and between four successive generations. The aim of the study was to identify individual seed retaining plants over these generations. Selection of individual plants within generations was based mainly on seed yield per inflorescence as well as inflorescence shape as an indicator of seed retention. From approximately 1750 parent plants, 144 D. richardsonii and 19 D. linkii accessions remained in the fourth generation selections. Of these seven D. richardsonii and three D. linkii plants were identified as having high inflorescence seed yield. Over the four ge nerations, mean inflorescence seed yield (g per five inflorescences) increased from 0.31 to 0.42 g for D. richardsonii and from 0.12 to 0.39 g for D. linkii. Mean seed yields for selected lines in the fourth generation were 0.80 g for the seven D. richardsonii selections and 0.59 g for the three D. linkii plants. Selection resulted in an increase in glume width and the number of days to first flower in both species. Mean inflorescence length and width varied little over the four generations. Between successive generations (parent, G2, G3 and G4) 10, 5 and 6 D. linkii plants had inflorescence seed yields higher than the mean, compared with 42, 46 and 35 G4 D. richardsonii plants. However, only 17 of the D. richardsonii and three of the D. linkii plants had inflorescence seed yields greater than the mean in all generations. Autumn inflorescence seed yields in the third and fourth generations were also used as additional selection criteria for selecting seven D. richardsonii plants for further evaluation and possible commercial release.
Isoquinoline alkaloids and keto-fatty acids of Argemone ochroleuca and A. mexicana (mexican poppy) seed.II. Concentrations tolerated by pigs
Authors: Takken G , Fletcher MT , Blaney BJ
Published: November 2004

Two batches of Mexican poppy seed were fed to pigs in several experiments to determine tolerable concentrations in pig diets. One batch, botanically identified as Argemone ochroleuca, was split and one half exposed to sunlight after milling. Sunlight rendered A. ochroleuca seed non-toxic at 4% in the diet, whereas 1% of freshly milled seed was toxic within 3-4 weeks. Signs of toxicity were pronounced reductions in feed intakes, lethargy, reddening of the skin and mild diarrhoea. The relative toxicity of the sunlight-exposed and freshly milled seed could not be explained in terms of the contents of the alkaloids sanguinarine, chelerythrine, protopine or berberine, but may be explained by the total isoquinoline alkaloid contents, of which the major components are dihydrosanguinarine and dihydrochelerythrine. These latter alkaloids were previously thought to be non-toxic. Based on pig performance data and alkaloid contents of different batches of A. ochroleuca, we suggest a safe tolerance of 0.2% in the diet of grower pigs, and up to 1% for finisher pigs. Similar concentrations of A. mexicana should be tolerated, based on alkaloid contents.
Catabolism and synthesis of amino acids in skeletal muscle: their significance in monogastric mammals and ruminants
Authors: Teleni E
Published: November 2004

The enhanced rate of synthesis and catabolism of amino acids in, and their release from, skeletal muscle, particularly during fasting, exercise and metabolic acidosis, highlight the integrative role of muscle in protein-energy metabolism. This review discusses aspects of such changes in muscles of monogastric mammals and ruminants. The glucose-alanine cycle, as it was originally proposed, has been well substantiated by studies using human and rat muscles. An alternative proposal, which suggested that other amino acids make a major contribution to the carbon skeleton of alanine synthesized in muscle, is less convincing, since some of the inhibitors and substrates used in relevant studies have been demonstrated to have multiple rather than specific effects. In the ruminant, the glucose-alanine cycle is quantitatively less significant than in human. The probable reason for this difference is the limited available pyruvate in ruminant muscle for transamination to alanine. This may be due to a lower carbon flux through the glycolytic pathway and/or to significant activity of the anaplerotic enzyme, pyruvate carboxylase. It is suggested that glutamine is the more important carrier of carbon and nitrogen out of skeletal muscle and that alanine may serve only as an ancillary vehicle to transport carbon and nitrogen when the availability of pyruvate for transamination in muscle is high. The more diverse role of glutamine (cf. alanine) in acid-base balance, as a respiratory fuel in the cells of the immune system and the epithelia of the small intestine, where it may also be converted to alanine for subsequent gluconeogenesis in the liver, is consistent with this suggestion.
The development of oyster diets
Authors: Nell JA
Published: November 2004

Although oyster larvae and spat have been reared successfully on algal diets for many decades, these are expensive to produce and do not always synchronize with hatchery requirements; considerable research has been conducted to determine which and why certain algal species are most appropriate and to investigate substitutes to algal feeds. Algal concentrates, commonly used in the United States, have overcome some problems associated with fresh algal feeds. However, work continues to develop cheaper non-algal alternatives. Recent promising advances have been in the formulation and preparation of experimental microencapsulated diets. However, further work upon capsules is required before the process can be commercialized. The possibility of rearing and substituting marine yeasts and bacteria for algae is an exciting and cost competitive alternative even to the microencapsulation approach.
Whither animal nutrition
Authors: Annison EF
Published: November 2004

Increased livestock production in developed countries, achieved largely by genetic improvement, improved feeding and disease control is likely to be maintained by technologies which include the use of transgenic animals, hormonal manipulation and the better definition of nutrient requirements. The latter objective will be facilitated by developments in quantitative nutrition which include improved analytical techniques such as NMR and NIR, and new methods for the continuous measurement of energy expenditure in defined tissues, and in whole animals. These new methods based on the measurement of blood flow by ultrasound, and of blood oxygen content by fibre optic technology, supplement arterio-venous difference and isotope dilution approaches which have proved so successful in recent decades.
Phenolic acids in the fibre of some tropical grasses, effect on feed quality, and their metabolism by sheep
Authors: Lowry JB , Sumpter EA , McSweeney CS , Schlink AC , Bowden B
Published: November 2004

A feature of the composition of dry-season tropical grasses, which may in part account for their lower digestibility, is the relatively high content of hydroxycinnamic acids covalently bound in the cell wall. The main phenolic acids liberated on mild alkaline hydrolysis in 19 species of native and introduced grasses in North Queensland were p-coumaric and ferulic acids, with the former predominating in 16 species. Caffeic acid was found in three species and sinapic acid in trace amounts. Total acids occurred at approximately 10 g/kg in most species, but were found at 50 g/kg in one species. When five of the species were fed as the sole diet to sheep, intake and digestibility were not clearly related to phenolic acid level in the diet. However, output of hippuric acid in the urine increased with the daily dietary intake of phenolic acids, and nitrogen excreted as hippurate was equivalent to as much as 17% of the total nitrogen in the diet. The effect of free acids on rumen function was tested by adding p-coumaric and ferulic acid directly to the diet. In contrast to the implications of numerous in vitro studies, intake and digestibility were not affected. Dry matter loss from intraruminal nylon bags was also not affected by administration of these compounds. In addition to hippuric acid, cinnamoylglycine was identified as a urinary metabolite. This appeared in animals on most of the grass diets, and was enhanced following administration of ferulic or p-coumaric acid, but not benzoic acid. It seems that phenolic acids liberated from the cell wall are unlikely to have an adverse effect on rumen microbial metabolism, but impose a serious nitrogen loss for animals on diets already deficient in nitrogen.
Restricted growth of lupin and wheat roots in the sandy A horizon of a yellow duplex soil
Authors: Dracup M , Gregory PJ , Belford RK
Published: November 2004

Yellow duplex soils are the dominant soil type in the cropping region of Western Australia, but crop yields on these soils are often variable and below potential. We are seeking to understand the causes of the spatially variable crop growth, and a preliminary study conducted in 1988 at a site east of Beverley indicated that variable shoot growth was associated with variable early (< 6 weeks after sowing) root growth in the sandy A horizon. The present study aimed to identify the constraints to early root growth by locating the position in the A horizon where root growth becomes restricted and measuring the local soil properties. In poor growth areas, root penetration slowed markedly at about 15 cm (about 2 weeks after sowing), while in the good growth areas roots continued to grow downwards at about 8 mm day-1 for lupin and 4 mm day-' for wheat. The soil was a particularly difficult environment for root growth, with generally low pH, low K and B, low porosity and aeration and high strength. Roots in poor growth areas appeared to experience greater mechanical impedance than in the good areas, most likely due to much lower clay contents leading to higher frictional resistance to particle movement or less stability of soil pores created by past roots or fauna.
The Southern Oscillation Index as a predictor of seasonal rainfall in the arable areas of the inland Australian subtropics
Authors: Russell JS , McLeod IM , Dale MB , Valentine TR
Published: November 2004

A detailed study has been carried out in four regions in the subtropics of Eastern Australia to determine the relationship between the Southern Oscillation Index (SOI) and subsequent seasonal rainfall. The period studied was from 1915 to 1991 for 3-monthly periods of spring (SON), summer (DJF), autumn (MAM) and winter (JJA). The 3-monthly prior SOI values were plotted against seasonal rainfall of the four regions and four seasons. These data were widely scattered but with a linear trend showing increased seasonal rainfall as the SOI increased. Linear trends were plotted for each season and region. Comparisons were made between the use of the ACE algorithm, which transforms the SOI and rainfall data, and the use of linear trends. Polynomials were used to calculate equations for each region and season, but only spring and summer produced satisfactory ACE functions. Estimates were made of spring and summer rainfall relative to prior SOI values for each region. While the SOI as a predictor of rainfall broadly estimates spring and summer rainfall, this variable has limited usefulness on its own. One of the options available with the ACE program is that additional independent variables can be added as required. Current research suggests that sea surface temperature data from specific ocean areas surrounding the Australian continent is the most useful additional variable at present. However the complexity of such an analysis is greatly increased.
The concentration of fat, protein and lactose in sows' colostrum from sucked and unsucked glands during lactogenesis II
Authors: Atwood CS , Hartmann PE
Published: November 2004

The relationship between the changes in the composition of colostrum and the removal of colostrum from individual glands during lactogenesis II in the sow was investigated. Sequential samples of colostrum were collected from all mammary glands on six sows during the farrowing period, and the amount of colostrum removed from each gland was measured by weighing the piglets at 15 min intervals. Prior to farrowing, there were large between sow variations in colostral fat (c.v. 39.8%) and protein (c.v. 22.9%) compared with lactose (c.v. 9.5%), but less within sow variations for these components (< 13.2%). From the commencement of farrowing, the sucked glands of all sows showed a significant increase in the concentration of colostral fat from 45.2 g/L to 76.1 g/L, but no consistent significant changes in the concentration of protein and lactose. The unsucked glands of all sows showed no consistent significant changes for fat, protein or lactose. Analysis of individual glands showed that 27 of the 34 sucked glands had a positive correlation between fat concentration and amount of colostrum removed. It was concluded that the withdrawal of colostrum from the mammary glands is an important component in the progressive increase in colostral fat during lactogenesis II in the sow.
The nutritive value of Persian clover (Trifolium resupinatum) herbage grown under irrigation in northern Victoria
Authors: Stockdale CR
Published: November 2004

A series of experiments is described which considered the nutritive value of Persian clover (Trifolium resupinatum) (cv. Maral) herbage grown under irrigation in northern Victoria. Digestion studies were undertaken with sheep and dairy cows, and the degradation of herbage samples in nylon bags was evaluated. Digestion coefficients were estimated, leaf and stem characteristics were measured, mineral and amino acid profiles were obtained, and protein degradabilities were assessed throughout the period of growth of Persian clover. Freshly harvested Persian clover herbage utilized before flowering appears to be an excellent feedstuff for ruminants, and its chemical composition remains relatively constant until late spring. In vivo OM digestibilities were in the range, 75-85%, although this depended on feeding level and time of the year. When vegetative, nitrogen content ranged from 3.0 to 4.6%, and neutral and acid detergent fibre levels were 24-34 and 21-27%, respectively. Acid detergent lignin concentrations were between 2.1 and 4.5% of dry matter. Dry matter contents of the herbage were often very low; this could influence intake and digestion. The chemical composition of leaves and petioles/stems were very different. The digestibility of the leaf fraction was often much lower than that of the petiole/stem fraction, but its nitrogen content was higher. Reasons for this, and their implications, are discussed. Protein degradability in the rumen was lower than expected (<70%); this was attributed to very fast rates of flow of digesta out of the rumen. Herbage minerals generally appeared to be adequate. Implications of the degree of degradation of individual amino acids and minerals in the rumen are discussed. The use of chemical characteristics to predict the digestibility of Persian clover herbage is considered and discussed.
The influence of herbage water consumption on the nutritive value of Persian clover for dairy cows and sheep
Authors: Stockdale CR
Published: November 2004

Three experiments were done with lactating dairy cows and one with wether sheep to study the effects of adding water to, or removing water from, fresh Persian clover on its apparent digestion and utilization in ruminants. In these experiments, the dry matter content of freshly harvested herbage averaged 10%; this was extended by wilting herbage for 12-24 h, adding a small amount of dry feed to the diet or loading the rumen with additional water. This resulted in mean water consumption ranging from 62 to 173 L/day in lactating cows. Water consumption per se appeared to have no effect on apparent digestibility coefficients in the total gastrointestinal tract or milk production (P > 0.05) at either low or high levels of feeding. However, digestibility coefficients were significantly lower (P < 0.05) when wilted Persian clover herbage was fed to animals, with concomitant reductions in milk yield; most of this reduction was due to herbage respiration and enzymatic losses probably associated with the breakdown of non-structural carbohydrates. It has been suggested that digestibility coefficients may be reduced with forages of very high water content due to reduced mean retention times of digesta in the rumen. Chromium dilution rates in rumen fluid were fast and there was a tendency for these to be positively related to water consumption. Therefore, while there may have been reduced digestion of nutrients in the rumen with higher flow rates, this must have been countered-balanced by greater digestion in the intestines.
The impact of chlorsulfuron and diclofop-methyl on nutrient uptake by wheat.
Authors: Osborne LD , Robson AD , Bowran DG
Published: November 2004

The effect of the herbicides chlorsulfuron and diclofop-methyl on nutrient uptake and utilization by wheat was examined in two glasshouse and one field experiment. In the glasshouse, chlorsulfuron decreased shoot weight, root weight and root length. Phosphorus uptake was decreased by chlorsulfuron, especially when combined with low phosphorus supply. Uptake of potassium was also decreased while uptake of nitrogen, calcium and magnesium was not affected. Under field conditions, chlorsulfuron decreased concentrations of a range of elements in plant shoots during early growth by up to 30%. This effect faded with increasing plant age. Chlorsulfuron treatment did not decrease nutrient concentrations in mature grain or grain yield. The elements in order of decreasing sensitivity to chlorsulfuron application were: macro-elements phosphorus, potassium > nitrogen, sulfur > calcium, magnesium and micro-elements zinc, copper > manganese > iron. There were differences in sensitivity to chlorsulfuron treatment between cultivars; Kulin was more sensitive than Reeves. Diclofop-methyl application had little effect on nutrient concentration in plant shoots. Zinc and copper concentrations were reduced in vegetative growth, although only copper concentrations were reduced in mature grain of Kulin. The uptake of nutrients which principally move to plant roots by diffusion was decreased more by herbicides than the uptake of nutrients which principally move by mass flow. It is therefore likely that the herbicides are modifying the ability of roots to explore soil rather than decreasing absorption at the root surface.
Effects of placement of elemental S and sulfate on the growth of two rice varieties under flooded conditions
Authors: Samosir SSR , Blair GJ , Lefroy RDB
Published: November 2004

Sulfur deficiencies are increasing in rice producing areas as a result of the increasing use of S free fertilizers. The presence of oxidized and reduced soil layers in flooded soils affect S availability to rice plants. A glasshouse experiment was conducted where 35S-labelled sulfate or elemental S was either broadcast onto the surface soil soon after transplanting or incorporated in the 7-21 cm soil layers 30 days before transplanting. The soil used was an S deficient Aquic Haplustalf. Two rice varieties C4-63 and Pulu Bolong, which had high and low O2 diffusion rates from roots respectively, were used in the study where plants were harvested at 42 days after transplanting (dat) and at maturity. Rhizosphere oxidation and root growth were factors contributing to the higher fertilizer S uptake at 42 dat in C4-63 than in Pulu Bolong. Filled grain yield was higher in C4-63 than Pulu Bolong. At 42 dat shoot yields, and at maturity straw yields, were highest in the surface sulfate (SS) treatment. Uptake of S derived from the fertilizer, relative to total S taken up by the plant averaged over the two varieties was 82% in the SS, 52% in surface elemental (SE), 34% in deep sulfate (DS) and 8% in the deep elemental (DE) treatments. At maturity the values were 51% (SE), 42% (SS), 30% (DS), and 5% (DE). The lower values for deep placement were due to lower oxidation of elemental S and decreased root activity at depth. There was a significant time x fertilizer placement x soil layer x variety interaction in the amount of fertilizer S recovered in the KH2P04- extractable sulfate and sulfide soil pools at 42 dat and maturity. At maturity, 34 to 74% of the fertilizer S was recovered in the soil sulfate and sulfide pools and in the algae and surface water in the presence of plants, and 20 to 34% in the pots without plants. The data indicate that surface application results in greater utilization of fertilizer S and suggest that combined P/S fertilizer sources are likely to be more efficient than N/S sources.
Application of cytokinins to flowers to increase pod set in Lupinus angustifolius L
Authors: Atkins CA , Pigeaire A
Published: November 2004

Exogenous application of a 2 mol m-3 buffered solution of N6 benzylaminopurine (BAP) to flowers on the main stem inflorescence of Lupinus angustifolius L, cv. Danja profoundly altered reproductive development by reducing post-anthesis abscission of flowers and small pods. The same effect of BAP was recorded for a mutant (abs-) of cv. Danja, in which organ abscission was completely absent, indicating that localized application of cytokinin enhanced reproductive development rather than reduced pedicel abscission per se in the parent line. Application to pedicel and sepals at the open flower stage completely eliminated flower abortion on the main inflorescence, compared with less than 50% pod initiation on untreated inflorescences, more than doubled final pod yield on the main inflorescence and increased the number of mature pods on the whole plant by 33%. A single dose of BAP, to an inflorescence which bore flowers ranging in their stage of development from post-anthesis to immature flower buds, significantly increased the number of pods initiated and at final harvest, measured on a per plant basis. A number of synthetic and naturally occurring cytokinins, including zeatin riboside and dihydrozeatin riboside, were also effective. BAP application induced a longer period of flowering and resulted in a considerably thickened raceme. This was most marked at the distal end which showed enhanced cambial development and secondary vascularization compared with untreated controls. The positive effects of BAP application on pod initiation were not restricted to cv. Danja but were found also for cv. Warrah and cv. Gungurru, both of which have enhanced pod set compared with Danja. Enhanced pod initiation on the main inflorescence generally reduced the number of pods developing on branch inflorescences. Additional application of BAP to flowers on branches, even at the most opportune time and at the most effective site, did not enhance pod initiation and, in some cases, significantly reduced pod set on these branches. The data indicate that it would be very difficult to exploit the positive effect of exogenous cytokinin application on pod set in field crops of lupin. However, selection or genetic engineering of plants with higher levels of endogenous cytokinins in flowers or flower parts at anthesis may provide a means by which to assess the importance of this factor in determining yield stability.
Control of annual grasses by spraytopping and the effect on triticale grain yield
Authors: Dowling PM , Nicol HI
Published: November 2004

IA range of pre-season management treatments was imposed on a mixed annual grass sward in October 1987, prior to planting triticale into a cultivated and a direct-drilled seedbed in June 1988. The management treatments included three rates of glyphosate: Roundup� (110, 180, 360 g a.i./ha); two rates of paraquat: Gramoxone� (100, 200 g a.i. ha); and one rate of fluazifop-butyl: Fusilade� (53 g a.i./ha � Pulse� wetting agent). All treatments decreased potential grass regeneration, with V. bromozdes being the least affected. Improved control was achieved by increasing application rate, and by adding a wetting agent to fluazifop. Actual grass seedlings emerging within the crop followed a similar pattern to potential grass regeneration. Grass emergence, particularly of V. bromoides and L. rigidum, was always greater on the direct-drilled seedbed. Grain yield was greater on the prepared seedbed. On both seedbeds, yield was inversely related to grass DM 97 days after sowing (DAS) and grass weed seedling numbers 50 DAS. The effectiveness of the herbicides appeared to be related to maturity dates of the target species. The high potential seed-set of the annual grasses present (> 500 000/m2), of which V. bromozdes was the main component, highlights the difficulty of controlling such species. It is suggested that the large apparent decline from total seed-set to potential seedling numbers (14000/m2) resulted from the high stocking pressure by sheep over summer. For a number of annual grasses, a more rapid method for determining seed number based on seed weight and seedhead number is proposed, providing a more informed basis for decision making. We conclude that spraytopping to maximize yield of later sown direct-drilled crops (e.g. triticale) is essential, despite the difficulty in optimizing timing of spraytopping in mixed pasture swards.
The nitrogen economy of broadacre lupin in southwest Australia
Authors: Unkovich MJ , Pate JS , Hamblin J
Published: November 2004

The time courses of above- and below-ground accumulation of biomass and N were followed in a crop of narrowleaf lupin (Lupinus angustifolius L. cv. Illyarrie) at Geraldton, W.A., and concurrent N2 fixation assessed using the 15N natural abundance technique. Crop biomass peaked at 10 t DM and 231 kg N ha-1 with 13% of this N below ground. The crop accumulated the bulk (90%) of its N through symbiotic N2 fixation. Of the 164 kg total plant N ha-1 remaining in recoverable biomass at maturity 44% was recovered as grain, 49% as other above-ground residues and 7% as roots. Despite a decrease in recoverable N of 67 kg ha-1 between peak biomass and maturity, 96 kg N ha-1 was returned as crop residues after grain harvest. Investigation of six farm crops in the study region gave values for nitrogen accumulation at peak biomass ranging from 199 to 372 kg ha-1 of which, on average, 86% (222 kg ha-1) was fixed from the atmosphere. Predicted N returns to the soil from fixation averaged 65 kg ha-1, though the range (32-96 kg ha-1) indicated that south-west Australian lupin crops provide somewhat variably sized pools of mineralizeable crop residues for following cereal growth.
Genetic parameters for Australian maternal and dual-purpose meatsheep breeds. I. Liveweight, wool production and reproduction in Border Leicester and related types
Authors: Brash LD , Fogarty NM , Barwick SA , Gilmour AR
Published: November 2004

Analyses of two separate Border Leicester data sets are reported. In the first set, genetic parameters were estimated for 14 month liveweight and greasy fleece weight from 1312 ewe and ram records representing 75 sires of the Border Leicester and Glen Vale breeds (a related genotype) using derivative-free REML procedures. The heritability estimate for liveweight was 0.24 � 0.07 and greasy fleece weight was 0.17 � 0-05, with the genetic correlation being -0 21 � 0 -30 and phenotypic correlation 0.54 � 0.02. In the second data set, reproductive performance was analysed and genetic parameters were estimated from 7395 joining records for 1604 ewes, representing 165 sires, from two Border Leicester stud flocks. Reproduction traits analysed were fertility (ewes lambing of ewes joined), litter size (lambs born per ewe lambing) and lambs born (per ewe joined). The studs differed in performance for all reproductive traits; fertility (67 v. 82%), litter size (1-27 v. 1-43) and lambs born (85 v. 117%). The estimates of heritability and repeatability respectively for ewe performance were: fertility 0.01 � 0.01 and 0.05 � 0 01, litter size 0.01 � 0.02 and 0.05 � 0.01, lambs born 0.00 � 0.01 and 0.06 � 0.01. Estimates of heritability for average ewe lifetime performance were 0.04% 0.05 for fertility, 0-02 �0.05 for litter size and 0.03 � 0.05 for lambs born, based on averages of 4.6 joining and 3.5 litter size records for ewes. The genetic correlations between lambs born and its components fertility (0.96 � 0.18) and litter size (0.83 � 0.44) were high, with the genetic correlation between fertility and litter size being 0.65 � 0.52. Implications for breeding programs for Border Leicester flocks within LAMBPLAN are discussed.
Effect of potassium fertilization of pyrethrum (Tanacetum cinerariifolium) on yield, pyrethrins concentration in dry achenes and potassium concentration in soil and plant tissues
Authors: Salardini AA , Chapman KSR , Holloway RJ
Published: November 2004

Pyrethrum (Tanacetum cinerariifolium), a small perennial plant, has been commercially grown for production of pyrethrins (Py) in Tasmania since 1983. Two field experiments were conducted on clay loam and sandy clay loam krasnozem soils at Harford and North Motton in the northern region and a two-year experiment on an alluvial sandy loam at Ouse in the southern region of Tasmania to study its potassium (K) requirements. Potassium, at rates up to 200 kg K ha-1, was band-placed at planting (basal K) of pyrethrum splits. At Ouse in the spring of the following year up to 100 kg K ha-1 was side-dressed in the subplots. No achene yield response was observed at Harford with the soil Colwell K (Kc) of 80 mg K kg-1 and North Motton (Kc = 132), but at Ouse (Kc = 50) in the first year a maximum increase of 86% in the achene yield was attained at 50 kg K ha-1. In the second year at Ouse, the achene yield response occurred with residual basal K up to the 200 kg ha-1 rate, where the achene yield was 3.9-fold greater than the control. In addition to the increase gained from the residual K in the second year, 50 kg side-dressed K ha-1 increased the achene yield by a maximum of 50%. Basal K did not have any effect on the Py concentration of the first year crops, but it increased the Py concentration in the second year crop at Ouse. Side-dressed K also increased the Py concentration. The Py yield at the highest rate of 200 kg basal and 25 kg side-dressed K ha-1 was more than 6.5-fold that in the control treatment. The Kc and the concentration of K in apical tissues were correlated to the rates of applied K, achene yield and Py yield, and their potential as techniques to predict pyrethrum response to K application is discussed.
Cutaneous circulation is correlated with Merino wool production
Authors: Hocking Edwards JE , Hynd PI
Published: November 2004

Laser Doppler velocimetry was used to investigate the cutaneous circulation and its relationship to wool growth in Finewool and Strongwool Merinos. Skin blood flow measured with the laser Doppler velocimeter (LDV) was highly correlated with estimates of blood flow obtained using 57Co-labelled microspheres (R2 = 0.85; P < 0.01), although the absolute values estimated by the microsphere technique were significantly higher (P < 0.001). Strongwool Merinos had a greater rate of blood flowing through the skin than Finewool Merinos, and this was associated with both wool production per unit area of skin (R2 = 0.27, P < 0.01) and with the total volume of germinative tissue in the skin (R2 = 0.54; P < 0.04). The relationship between the microvascular anatomy of the skin and blood flow was also examined in four Finewool Merinos and four Strongwool Merinos. Silicone rubber was infused into the deep circumflex iliac artery within the abdominal flank, from which an index of the area of vascular tissue per unit volume of skin was estimated. This index was not related to blood flow, wool growth or follicle density within nor between strains of Merinos. Both the usefulness and limitations of the LDV are discussed, and it was concluded that (a) blood flow has an important role in the level of wool produced both within and between strains of Merinos, and (b) laser Doppler velocimetry is a useful tool for the study of blood flow in the skin of sheep.
Plant population dynamics in subterranean clover and murex medic swards. II. Plant population density
Authors: Blumenthal MJ , Ison RL
Published: November 2004

It is possible that the use of harder-seeded varieties of sub. clover (Trifolium subterraneum) and the recently domesticated murex medic (Medicago murex) may improve annual legume persistence in pasture leys. To determine the mechanisms of production and persistence in these two species, plant population density changes in single seed (sprayed) and naturally regenerating (unsprayed) swards were monitored in four varieties of sub. clover and two lines of murex medic over a three year period at Forbes in central-west N.S.W. Seedling recruitment was very sensitive to soil water and temperature at the time of germination and emergence, particularly in murex medic. Murex recruitment under irrigation was at least four times greater than without irrigation on a germinable seed basis. Irrigation of sub. clover swards did not improve recruitment to the same extent as it did in murex medic. Even the soft seeded cultivars (Junee, Seaton Park and Woogenellup) can regenerate from residual seed in the year following a year in which no seed was set, although there are qualifications for Woogenellup. Plant population density (D) declined over the growing season, despite the specific effects of environment and management; initial plant population density (Di) appears to have the greatest influence on dry matter production over the growing season.
Nutritional responses in wool growth by four Merino genotypes of differing wool growth performance
Authors: Lee GJ , Williams AJ
Published: November 2004

Sheep from four Merino flocks, different in annual clean fleece production when grazed together, were offered a range of nutritional treatments to compare their ability to digest dietary organic matter (experiment 1) and to compare the relationships of wool growth and fibre diameter with nutrient intake (experiment 2). The sheep were selected from a finewool (Fl), a strong wool (S), and two medium-Peppin (MP6 and MP10) flocks. The nutritional treatments varied intakes of two pelleted diets-B and F. Diet B consisted of oat grain, lucerne chaff, and oaten straw, while diet F was as for B but fortified with fishmeal. The digestibility of both diets was negatively related to the level of intake, and there were some differences between the flocks in their ability to digest organic matter. Clean wool growth per unit area of skin was curvilinearly related (P < 0.001) to N intake, but was not influenced by diet per se. The regression coefficient for the relationship of clean wool growth with N intake and the estimated maximum wool growth rate of flock F1 were less than the other flocks. However, flock MP10 grew less wool than flocks S and MP6 at any given intake. Variation in (fibre diameter)2 accounted for 0.6 of the variation in wool growth, with responses in fibre diameter to intake being similar to those observed in wool growth. The responses in plasma cystine of the flocks to N intake differed, with the relationship for flock F1 being curvilinear and reaching a maximum at an intake of 27 g N day-1, while the responses of the other flocks were essentially linear. The relationships between plasma cystine level and wool growth differed between the flocks such that wool growth of sheep from flocks S and MP6 was more responsive to increased plasma concentration of cystine.
Genetic parameters for ultrasound fat depth and eye muscle measurements in live Poll Dorset sheep
Authors: Gilmour AR , Luff AF , Fogarty NM , Banks R
Published: November 2004

The study was conducted to estimate heritabilities and genetic correlations for liveweight, fat depth at the C site and eye muscle depth, width and area measured by B mode ultrasound on live young sheep. Records on 4338 animals were available for analysis, representing 161 sires and 79 managementlsex groups. The management groups were allocated to young (5-9 months), medium (10-13 months) and old (14-18 months) data sets for analysis, representing 89, 82 and 19 sires respectively. The heritabilities of liveweight, ultrasonic fat depth and ultrasonic eye muscle measurements were estimated after adjusting for managementlsex group, birth and rearing type, age class of dam and age of the animal. The heritability estimates for the three age data sets respectively were: for liveweight 0.19 � 0.06, 0.11 � 0.06 and 0.37 � 0.18; for fat depth 0.01 � 0.03, 0.18 � 0.07 and 0.28 � 0.15; and for eye muscle depth 0.15 � 0.05, 0.11 � 0.06 and 0.l6 � 0.11. After adjusting for sex/management group and liveweight within sex (the other factors listed above being no longer significant), heritability estimates were: for adjusted fat depth 0.11 � 0.05, 0.33 � 0.09 and 0.29 � 0.16 and for adjusted eye muscle depth 0.l5 � 0.06, 0.l5 � 0.06 and 0.19 � 0.12. The heritability estimates for eye muscle area, estimated as the area of an ellipse with dimensions equal to the measured depth and width, were about 10% lower than for eye muscle depth, but the genetic correlations with depth, in each case were 0.94 or higher. The heritability estimates for eye muscle width were less than 0.05 in young and medium age animals and 0.12 to 0.15 in old animals with high genetic correlations with depth which were not different from 1.00. Ultrasound measurements of fat depth at the GR site were available on 2065 lambs under 8 months of age representing 76 sires in 33 groups. The heritability estimates for fat depth adjusted for liveweight, at the GR and C sites in these lambs were both 0.10 � 0.05 with the genetic correlation between sites being 0.76 � 0.19. There is potential for including eye muscle depth in selection indices to improve leanness. Ultrasound measurement of eye muscle width and area will not improve prediction of eye muscle over that attained by measuring eye muscle depth. Predicted responses in liveweight, fat depth and eye muscle depth for five breeding objectives for terminal sires, using the appropriate LAMBPLAN selection indices, are shown and discussed.
Growth and yield of sorghum lines extracted from a population for differences in osmotic adjustment
Authors: Tangpremsri T , Fukai S , Fischer KS
Published: November 2004

From 47 S2 lines which had been extracted from a random mated population of sorghum, eight lines for a glasshouse experiment and four lines for a field experiment were divergently selected for variation in osmotic adjustment, and were grouped into two, High and Low osmotic adjustment (OA). Both the glasshouse and field experiments examined whether osmotic adjustment modified the plants' response to soil water deficit and also whether grain sink demand for assimilates, varied by removal of 50% spikelets, affected osmotic adjustment. In each experiment, there were well-watered control and water stress treatments. In both experiments, the dawn osmotic potential in the High OA group was always lower than in the Low OA group under water limiting conditions, and the difference was significant after anthesis. The difference in osmotic potential was about 0.1 MPa in the field and up to 0.25 MPa in the glasshouse. In the glasshouse experiment, removal of 50% spikelets at anthesis significantly decreased osmotic potential during grain filling, suggesting that osmotic adjustment is influenced by the availability of assimilates in the leaves. Under well-watered conditions, the two groups behaved very similarly in terms of maximum leaf area, green leaf area retention during grain filling, total dry matter production, grain yield and grain number in both experiments. Under water-limiting conditions, the High OA group produced larger maximum leaf area and had better leaf retention during grain filling. Despite similar water use, total dry matter was also significantly higher in the High OA group though the difference was small. Grain number was also greater in this group in both experiments, whereas grain yield was significantly higher in the High OA group in the field, but not in the glasshouse where severe water stress developed more rapidly. It is concluded that the adverse effect of water stress can be reduced by adopting sorghum genotypes with high osmotic adjustment. However, selection for high osmotic adjustment needs to ensure that osmotic adjustment is not solely due to small head size.
Effects of cereal grains on fibre digestion in vitro
Authors: Opatpatanakit Y , Kellaway RC , Lean IJ , Annison G , Kirby A
Published: November 2004

Cereal grains including wheat, barley, oats, maize and sorghum were incubated with strained rumen fluid in vitro with either ryegrass or lucerne in the ratios of 0:100, 25:75, 50:50, 75:25 and 100:0 at 3g�C for 24 h. Expected NDF digestibilities in mixtures of cereal grain and forage were calculated by interpolation between NDF digestibilities of each grain and of each forage. These were compared with measured NDF digestibilities to detect deviations due to synergism or inhibition. Wheat, barley and maize had inhibitory effects, whereas oats and sorghum had synergistic effects, on NDF digestibility with both forages.
Use of isozyme phenotypes for rapid discrimination among sugarcane clones
Authors: Gallacher DJ , Lee DJ , Berding N
Published: November 2004

Verification of cultivar identity is essential in routine plant breeding and associated research. The current study aimed to determine if scoring of isozyme phenotypes resolved with starch gel electrophoresis would provide a cheap, useful method of identifying sugarcane clones. One hundred Saccharum spp. hybrid clones selected at random from the Bureau of Sugar Experiment Stations's (BSES1s) parental germplasm collection at Meringa were surveyed for 20 enzyme systems. Fully expanded leaf or non-chlorophyllic leaf spindle tissue of field grown plants was used. Three enzyme systems (alcohol dehydrogenase, peroxidase and phosphoglucomutase) jointly yielded 11 reliable, inter-clonally variable markers. Isozyme variability in the population sample surveyed was lower than had been observed in earlier studies of progenitor Saccharum spp. The remaining enzyme systems were invariant or could not be scored reliably. An average of 3-52 band differences per pair allowed separation of 97% of all possible pair-wise combinations. Complete discrimination of clones cannot be achieved with these markers, but they are reliable for checking identity of suspected mislabelled clones.
Partition of nutrients and return to oestrus in lactating Bos indicus cows
Authors: Hunter RA , D'Occhio MJ
Published: November 2004

This study examined the hypothesis that partitioning of nutrients towards maternal tissue growth, rather than milk production, may favour a more rapid return to cyclic ovarian activity in lactating Brahman cows. Three strategies to decrease milk production in well-fed cows were tested. Continuous infusion of the somatostatin analogue RC-121 and immunization of cows against growth hormone releasing hormone had no significant effects on milk yield, cow and calf weight change and the duration of the period of anoestrus post-calving. Restriction of udder capacity by surgical occlusion of two teats reduced milk yield by about 20% (P < 0.001). During the first 6 weeks of lactation, cows with restricted udder capacity gained 0.31 kg/day compared with a loss of 0.08 kg/day by controls (P < 0.05). From weeks 7-20, both groups gained at 0.4 kg/day. The duration of the period of anoestrus after calving was approximately 6 months in each group. In experiments in which calves were weaned, all cows returned to ovarian activity within 16 days of weaning. It was concluded that purebred Brahmans preferentially partition nutrients towards the mammary gland and that partially redirecting nutrients towards maternal tissue growth rather than milk secretion did not result in a more rapid return to cyclic ovarian activity.