bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of bovine proteoglycan-II as a growth promotant
Authors: Gazzola C , Lindsay DB
Published: November 2004

Proteoglycan-II is a dermatan sulfate proteoglycan which binds peptide growth factors, and through this mechanism it has been shown to alter the growth of mammalian cells in culture. The possibility was tested that injections of proteoglycan-II could alter the growth of live animals. Proteoglycan-II from bovine occipital condyle articular cartilage was prepared, authenticated and injected into male Wistar rats. The injection of 125I-proteoglycan-II showed that it was absorbed and metabolized by the rats. Growth studies showed that treatment with proteoglycan-II at two levels of purity and at two dose rates produced no change (P > 0.05) in live weight gain, body composition or food conversion efficiency.
Epidermal growth factor and fluid balance: a review
Authors: Gow CB , Moore GPM
Published: November 2004

Lambs suffer from high mortality rates within the first 2-3 days after birth. The importance of sucking behaviour for the ingestion of colostrum and subsequently milk by the newborn animal is therefore seen as crucial for its survival and development. Epidermal growth factor (EGF) is a component of colostrum and milk (Read 1988; Gow et al. 1991) where it is thought to function as a promoter of gut maturation in young animals following ingestion. We recently reported (Gow and Moore 1992) a new physiological function for EGF, that of stimulating fluid intake in adult sheep. Here we present a review of the functions of EGF, particularly as they relate to lactation, body growth, appetite and fluid balance. We hypothesise that another function of EGF in mammary secretions may be to regulate body growth by altering sucking behaviour and activity in the neonate.
Regulation of nutrient partitioning growth and lactation
Authors: Bickerstaffe R
Published: November 2004

This paper will emphasize the impact of growth and lactation on partitioning nutrients, the role of biological signals and whether such signals can be influenced or modified. Factors considered are the mechanisms of controlling cell cycling, growth and differentiation; interaction or cross-talking between tissues (autocrinepeptides, tissue receptors, secondary messengers); effect of extrinsic and intrinsic signals on cellular growth (growth hormones, oncogenes); and manipulation of nutrient partitioning (mutated receptors, gene expression, targeting metabolic genes).
Role of computer simulation in the application of knowledge to animal industries
Authors: Black JL , Davies GT , Fleming JF
Published: November 2004

The net financial return of an enterprise depends on the interaction among a great many factors. Some of these factors relate to the animal, some to its diet, some to its environment, some to the prevalence of disease and some to circumstances outside the production enterprise such as the premiums paid for products of different quality, the relative price structure of feeds and products, and the availability and cost of capital, labour, breeding stock and other resources. Although there has been a great deal of research into many of these factors, the complexity of the interactions between them makes it virtually impossible for the human mind to assess accurately the consequences of alternative management strategies on either the efficiency of production or the long-term profitability of a livestock enterprise. By transforming the concepts and knowledge into mathematical equations and integrating them in computer programs using simulation modelling techniques, this vast store of information can be applied directly to improving the management of commercial animal enterprises. Models are also valuable for defining research priorities. These simulation models should, as far as possible, be based on descriptions of the mechanisms perceived to determine animal function, not on empirical relationships of correlation and association. This need for mechanistic models has major implications for the direction and nature of future research into animal function. Mechanistic models of animal performance alone are unlikely to result in the widespread application of knowledge to the animal industries. Models must be integrated with other modules that cover the major areas of an enterprise determining its profitability, as well as with programming features that make the whole Decision Support Software System easy to use and interpret by industry personnel. The animal model is likely to represent less than 20% of a commercially useful package. A major factor limiting the application of animal growth models is lack of an adequate description of the conditions within commercial enterprises. Collection of such data is difficult and frequently regarded as unattractive by scientists and funding organisations, but it is essential for effective application of existing knowledge through simulation models. Furthermore, industry must make frequent measurements of factors determining animal performance and enterprise profitability if the significance of predictions from animal models is to be evaluated fully. An example is presented illustrating how simulation models can improve the biological efficiency and profitability of a commercial animal enterprise when this information is available.
Modification of animal growth with growth hormone and insulin-like growth factors
Authors: Ballard FJ , Francis GL , Walton PE , Knowles SE , Owens PC , Read LC , Tomas FM
Published: November 2004

A brief overview is presented on the effects of growth hormone administration to rats, humans and animals of economic significance with an emphasis on the differences in responsiveness observed between species. Unlike the situation in humans, pigs, cattle and sheep, growth hormone is only active at very high doses in pituitary-complete rats, and it is essentially inactive in poultry. The growth hormone resistance in rats and poultry can be explained by equivalent reductions in the ability of the hormone to elicit increases in circulating IGF-I concentrations. However, the rat is not resistant to IGF-I itself because the administration of this growth factor to both male and female animals leads to marked increases in live weight gain and nitrogen retention as well as a more efficient conversion of feed to live weight. Selective growth of the gut, kidneys and spleen is also observed. To date, no IGF-I growth responses have been demonstrated in animals of economic significance, although results of acute experiments show the expected increased tissue delivery of nutrients. It is suggested that the increased availability of recombinant IGF-I and especially genetically engineered potent variants will lead to extensive growth trials in the next few years. The cc-administration of IGF peptides and growth hormone also provides an interesting opportunity because these two agents exhibit complementary effects that could lead to a synergistic growth response.
Genotypic variation among Glycine spp. for ability to acclimate to saturated soil
Authors: Hartley RA , Lawn RJ , Byth DE
Published: November 2004

The ability to acclimate to, and grow well under saturated soil culture conditions (SSC) is a ubiquitous trait in soybean (Glycine max) but little information has been reported about this novel adaptive trait in wild Glycine spp. The ability of 39 diverse accessions from one wild annual and eight wild perennial Glycine spp. to acclimate to, and grow in SSC was therefore evaluated, and responses compared with those of three cultivars of soybean. Plants were exposed to SSC 26 days after sowing, and measurements made, after a further month, of the number of nodules, leaf area, and dry matter accumulation of roots, stems and leaves. None of the wild perennial Glycine spp.(subgenus Glycine) acclimated to SSC. Necrotic tissue developed in some perennial accessions as soon as six days from the imposition of SSC, and all of the perennial accessions died during the experiment. In contrast, both of the annual species within subgenus Soja (soybean, and its presumed wild progenitor, G. soja) acclimated to SSC. The subsequent rate of recovery tended to be slower in G. soja than soybean. The responses are consistent with the hypothesis that the ability to acclimate to SSC is a wild-type trait, expression of which was amplified in soybean during domestication in rice-based agriculture.
Responses of laying hens to diets differing in isoleucine content
Authors: Mannion PF , Young RA , Fuelling DE , Barram KM
Published: November 2004

The responses of Hyline (WLxNH) and Tegel (WLxAO) strain laying hens offered six 'response' diets ranging in isoleucine content from 2.8 to 8.6 g kg-1 were examined. The required range of isoleucine content was obtained by formulating a summit diet containing a surplus of all essential amino acids, but a lesser surplus of isoleucine, and blending it in appropriate proportions with a basal diet, structured similarly to the summit diet, but deficient in all essential amino acids and protein. To test that isoleucine was the first limiting nutrient in the 'response' diets, an additional six 'test' diets were given. These were identical to the 'response' diets except for the addition of L-isoleucine which raised the total isoleucine content of each by an amount equivalent to the difference between two adjacent 'response' treatments. The 12 diets were given from 30 to 46 weeks of age (phase 1) and again from 54 to 70 weeks of age (phase 2) following an intervening recovery period. Responses to the diets, determined on data from the final 4 weeks of each phase, were attributed to differences in isoleucine intake. The apparent efficiencies of utilization of isoleucine for egg synthesis and for maintenance were similar for both strains. The daily isoleucine requirement of individual laying hens was estimated to be 9.91 mg g-l egg output plus 33.56 mg kg-1 liveweight per day. Curves describing the egg output response to isoleucine intake were calculated using the Reading model and optimum isoleucine intakes were derived for various liveweights, egg outputs and ratios of input costs and output values. For example, for a flock of hens with an average weight of 2 kg and producing an average of 50 g daily egg mass, the optimum isoleucine intake varied between 581 and 684 mg d-l.
Manipulation of the feeding value of senescing annual ryegrass (Lolium rigidum Gaud.) with imazethapyr and glyphosate
Authors: Crawford MC , Simpson RJ
Published: November 2004

The effect of applying imazethapyr [(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin- 2-y1)nicotinic acid] on the in vitro dry matter digestibility (IVDMD) of annual ryegrass was studied and compared with the effects of glyphosate [N-(phosphonomethyl)glycine] . Application of imazethapyr 20 days before anthesis delayed loss of digestible dry matter (DDM) more effectively than when applied at anthesis or 8 days after anthesis. Digestibility of the stems of ryegrass when measured at anthesis was 57.9% and 61.9% for 50 g (a.i.) ha-1 and 100 g (a.i.) ha-1 of imazethapyr, respectively, compared with 50.4% for the control. Application of either imazethapyr or glyphosate decreased dry matter yield initially, mainly because growth of seed heads was reduced. Both glyphosate- and imazethapyr-treated plants produced secondary tillers. In the case of the imazethapyr-treated plants, yield forgone as a result of herbicide treatment was recovered through the production of secondary tillers and because seed head yield were not suppressed to the same extent as in the gylphosate-treated plants. When applied 20 days before anthesis, both herbicides maintained stem IVDMD at 54-60% for up to 42 days after spraying, whereas IVDMD of stems in the control declined. The IVDMD of leaf sheaths was intermediate between that of stems and leaf blades and was improved by herbicide treatment. The IVDMD of leaf blades was unaffected by herbicide treatment. Herbicide treatments 20 days before anthesis therefore delayed loss of DDWI from the vegetative part of the sward for up to 22 days after anthesis. By comparison, in the untreated sward, DDM was lost at a rate of 34.4 kg per ha per day. The total DDM of swards (including seed heads) in all treatments did not differ.
National survey of viruses in pastures of subterranean clover. III. Equipment for large scale screening of viruses by ELISA
Authors: Hulse LB , Helms K , Waterhouse PM
Published: November 2004

Equipment for large scale enzyme-linked immunosorbent assay (ELISA) was developed for a 3 year nationwide survey of the incidence of four viruses in pastures of Trifolium subterraneum (subterranean clover) in New South Wales, Victoria, South Australia, Western Australia and Tasmania. Instruments were designed to (a) automate quantitatively the addition of buffer to plant samples passing through a sap extractor, (b) standardize the washing of plates in the various stages of the ELISA protocol, and (c) replace hand pipetting with a pneumatic foot-operated pipette.
Developing better strategies to improve grain quality for wheat
Authors: Wrigley CW
Published: November 2004

There are opportunities to improve the quality and-market value of wheat grain at all stages of production, storage and transport. An essential pre-requisite is a thorough knowledge of market requirements, both for the coming crop season and well into the future in the case of breeding programs and research planning. Elucidation of the molecular basis of grain quality is an important part of the overall strategy of quality improvement. The outcome expected from such studies will be the identification of key chemical components that can serve as markers for specific aspects of grain quality. The provision of screening tests for these marker compounds then permits intelligent quality testing at harvest, planning of genotype and environment to maximize quality, and selection of suitable genotypes at an early stage of breeding. This review describes the state of our present knowledge of grain quality at the molecular/chemical level (with particular references to dough quality for wheat), and it indicates how this knowledge can be put to practical use in better suiting wheat grain for processing requirements both in Australia and overseas.
A survey of proportional dependence of subterranean clover and other pasture legumes on N2 fixation in south-west Australia utilizing 15N natural abundance
Authors: Sanford P , Pate JS , Unkovich MJ
Published: November 2004

In an attempt to understand why pasture production in southern Australia has declined markedly in recent years a survey of the symbiotic performance of the legume component of annual pastures on 81 farms (243 sites) was undertaken in the southern coastal region of Western Australia. The 15N natural abundance technique was used to determine the percentage of plant nitrogen derived from the atmosphere (%Ndfa) using capeweed (Arctotheca calendula) as principal non-fixing reference species. %Ndfa values were then related to edaphic and management information, e.g. soil total nitrogen, soil pH, stocking rates and cropping history of the sites. The principal legume species encountered exhibited similar mean %Ndfa values but substantial variation in symbiotic performance was evident across the sites, viz, Trifolium subterraneum 72%Ndfa (n = 184, range of values encountered 0-100%), Medicago spp. 7l%Ndfa (n = 24, range 7-l00%), Lotus spp. 8l%Ndfa (n = 15, range 1-l00%), Ornithopus compressus 76%Ndfa (n = 15, range 25-100%) and Trifolium balansae 69%Ndfa (n = 7, range 0-100%). In the case of subterranean clover, the most widely occurring species, almost one third (29%) of sites surveyed recorded %Ndfa values within the range 0-65%, suggesting that symbiotic performance might well be quite widely limiting to herbage production in the study region. Of the 24 edaphic and management factors evaluated, only one, %A1 in shoot, DM showed a significant relationship with %Ndfa, with 40% of the pastures surveyed deemed at risk in terms of acidity related aluminium toxicity. Correlations of %Ndfa with soil pH and soil total N produced examples of high values %Ndfa for sub-clover being associated with very low soil pH or high soil N, suggesting possible adaptation of symbiotic partnerships to acidity or high mineral N.
The influence of mixtures of Stylosanthes spp. accessions on the occurrence of anthracnose caused by Colletotrichum gloeosporioides
Authors: Davis RD , Chakraborty S , Cameron DF , Irwin JAG , Boland RM
Published: November 2004

The effectiveness of using accession mixtures of Stylosanthes spp. to manage anthracnose (Colletotrichum gloeosporioides) in pastures in northern Australia was examined during three consecutive years. Two mixtures containing six accessions were compared with the components grown as pure stands. No significant differences in anthracnose incidence (proportion of infected plants/plot) were indicated between the two mixtures and the mean incidence of their respective components grown in pure swards. Areas under the disease progress curves for the accessions were not significantly different between pure and mixed stands of the cultivars other than Seca and Verano. Resistant cultivar Seca developed more disease in a mixture than in a pure stand, and moderately resistant Verano had less disease in a mixture than in a pure stand. In the short term, no apparent anthracnose control advantage is achieved in highly susceptible accessions of Stylosanthes spp. when they are included in mixtures with less susceptible accessions. Long term studies involving grazing animals are necessary to adequately evaluate control of this disease through the use of mixtures.
Nitrogen and sulfur metabolism and plasma thyroid hormone concentrations in fleeceweight-selected and control Romney sheep at two ambient temperatures
Authors: Sun YX , Lee J , Harris PM , Sinclair BR , Shelton ID , Blair HT , McCutcheon SN
Published: November 2004

This study was conducted to determine the effect of ambient temperature on nitrogen and sulfur metabolism in 7-month-old rams from the Massey University fleeceweight-selected (FW) and control (C) lines of Romney sheep. Eight rams from each line were exposed to either 6�C or 25�C ambient temperature under a constant photoperiod. Detailed studies of sulfur metabolism were made on four of the rams from each line at each ambient temperature. Intake and faecal output of dry matter and nitrogen were lower at 25�C than at 6�C, but there was no effect of ambient temperature on digestibility of either dry matter or nitrogen. Nitrogen balance was lower at 25�C than at 6�C, but none of the parameters relating to nitrogen balance was influenced by selection line. There were also no effects of ambient temperature or selection line on clearance rates of urea or creatinine. Blood samples were collected from the animals at 2 h intervals over a 24 h period to determine plasma concentrations of urea, creatinine, thyroxine and triiodothyronine. Although the between-line differences in concentrations of these hormones and metabolites varied throughout the 24 h period, and with ambient temperature, there were no consistent interactions between the effects of selection line and ambient temperature. There were no consistent effects of selection line, or interactions of selection line with ambient temperature, on sulfur and sulfate balances, concentrations of leucine, cyst(e)ine and glutathione in whole blood or on irreversible loss rates of leucine and cyst(e)ine. However, when considered across lines and ambient temperatures, both the whole blood concentrations (P < 0.10) and the irreversible loss rates (P < 0.05) of leucine and cyst(e)ine were positively related to midside wool growth. The only significant (P < 0.05) interaction between selection line and ambient temperature was observed in the wool sulfur concentration which was lower in the FW rams than in the C rams at 6�C, but not at 25�C. It is concluded that none of the metabolic measurements made in this study explains previous inconsistencies observed in metabolic differences between sheep from lines divergently selected on the basis of fleeceweight. Wool sulfur content was again shown to be a potentially useful predictor of genetic merit for fleeceweight, but no clear metabolic basis for differences between the lines could be demonstrated even with detailed measurements of sulfur metabolism.
The performance of pure lines derived from heterotic bread wheat hybrids
Authors: Uddin MN , Ellison FW , O'Brien L , Latter BDH
Published: November 2004

Comparisons of the grain yields of pure lines derived from heterotic hybrides were made with those of the F1 hybrids and their parents for four hand-made crosses, and with the hybrid in the case of the commercial hybrid cultivar Comet. Seventy-five F7 (F6 in the case of Comet) single seed descent lines from each cross were evaluated in hill plot experiments containing five plots of each parent and hybrid per replication. Mid-parent and high-parent heterosis averaged 17% and 10.7% respectively in the four hand-made hybrids. Thus hybrid breeding of wheat could achieve a significant yield advance because the parental genotypes were advanced breeding lines or commercial cultivars. The estimated genotypic value for grain yield of the best pure line derived from each cross was 98, 96, 94, 91 and 85% of the corresponding hybrid mean yield, and even higher yields could be expected from a larger sample of derived pure lines. A hybrid breeding program cannot therefore be justified solely on the basis of yield comparisons between hybrids and pure lines.
Transport and intracellular metabolism of major feed compounds by ruminal bacteria: the potential for metabolic manipulation
Authors: McSweeney CS , Mackie RI , White BA
Published: November 2004

Current knowledge of the uptake and metabolism of the major energy yielding and nitrogenous nutrients that are naturally available to ruminal bacteria is reviewed. The potential use of metabolic engineering to manipulate these metabolic pathways and improve nutrient utilization in ruminant animals is briefly discussed. Metabolic engineering is the use of recombinant DNA techniques to enhance microbial function by manipulating enzymatic, transport and regulatory functions of the cell. Examples of the use of metabolic engineering in industrial fermentation are also given.
An investigation of the grain yield adaptation of advanced CIMMYT wheat lines to water stress environments in Queensland. II. Classification analysis
Authors: Cooper M , Byth DE , Woodruff DR
Published: November 2004

The objective of this study was to use classification methodology to characterize the genotypic variation and line by environment (L x E) interaction for grain yield of a sample of advanced CIMMYT wheat lines and three local check cultivars tested over six Queensland environments. The environments were managed to differ in the magnitude of water stress they imposed on the lines at the critical developmental stage of anthesis. The grouping of lines was based on grain yield. The yield differences among the groups were investigated in terms of yield components and dry matter production and partitioning attributes. Groups of CIMMYT lines which outyielded the two groups which contained the three Queensland cultivars were identified. The yield advantage of the groups of CIMMYT lines decreased with increasing severity of water stress at anthesis and in the environment where the most severe stress was characterized there were no yield differences among the groups of lines. The yield advantage of the groups of CIMMYT lines was generally associated with a higher number of grains per unit area and in some cases a higher grain size. While phenology variation could account for some of the yield differences among the line groups there was considerable yield variation among line groups with similar phenology patterns across the environments. Additional measurements taken on the lines to characterize differences in dry matter production and the partitioning of the dry matter to yield components were not effective in explaining the yield variation among the groups of lines after the effects of phenology were taken into account. While the incidence of the large L x (water-stress) interactions encountered in this study would complicate selection for yield, the identification of groups of advanced CIMMYT lines which outyielded the Queensland cultivars in five of the six environments suggests that the L x (water stress) interactions do not preclude scope for further improvement of grain yield of wheat in Queensland.
Exogenous growth hormone releasing factors and cottonseed meal improve growth performance and composition of gain in lambs fed lucerne chaff ad libitum
Authors: Sainz RD , Hosking BJ , Hart FJ , Schricker BR
Published: November 2004

Forty-eight crossbred wether lambs (38 kg) were randomly assigned to two dietary groups (LUC, chaffed lucerne ad libitum; CSM, LUC plus 300 g cottonseed meal/lday) and two hormone treatment groups (rGRF, recombinant growth hormone-releasing factor (GRF); sGRF, synthetic GRF) plus controls (CON, excipient only), and slaughtered after treatment for 28 (n = 36) or 30 (n = 12) days. An initial slaughter group (n = 12) was killed on day 0. CSM reduced intake of lucerne chaff, but increased total feed intake. CSM also increased liveweight gain and wool growth, with no effect on feed conversion efficiency. CSM increased carcass weight and decreased subcutaneous fat depth, with no effect on dressing percentage or longissimus dorsi (LD) area. Meat tenderness tended to decrease with CSM supplementation. CSM increased carcass protein accretion ( P < 0.01), with no significant change in fat gain or final composition (P > 0.05). CSM increased weights of the pelt, liver and empty body, and decreased the proportion of digesta in liveweight. Weights of blood, forestomachs and small intestine tended to increase as well (P < 0.10). Both sources of GRF had similar effects. Intakes were not significantly affected by GRF, but feed conversion efficiency improved (P < 0.01) with GRF treatment (6.4 v. 9.2 feed:gain for GRF and CON respectively). Liveweight gains and final weights of the whole body and carcass were increased additively by CSM and GRF. GRF reduced fat depth and increased LD area, with no effect on dressing percentage, carcass length or meat tenderness. These changes reflected increased carcass protein and reduced fat contents, brought about by increased accretion of protein and water and reduced fat gain due to GRF. GRF increased weights of blood and liver beyond the general increase in body size. Cottonseed meal and GRF additively produced significant improvements in growth performance and carcass quality of young wether lambs fed a roughage diet. GRF may be a useful tool to improve livestock production under extensive and intensive conditions.
Nitrogen transactions in the rumen of sheep given a barley straw diet supplemented with untreated or formaldehyde-treated sunflower seed meal
Authors: Faichney GJ , Tagari H , Teleki E , Boston RC
Published: November 2004

The effect of formaldehyde treatment of the sunflower seed meal in a barley straw based diet on rumen N transactions was studied in two fistulated crossbred sheep using 15N-ammonia and 15N- and 14C-urea. Treatment decreased organic matter and N digestibility to a small extent, but substantially decreased urine N excretion so that N retention increased. Treatment resulted in decreases in ammonia and urea synthesis which were reflected in reduced rumen ammonia and plasma urea levels; the net flow of N from the rumen ammonia pool to the plasma urea pool was reduced by 50%. 56-65% of the bacterial N was derived from ammonia. The contribution of bacterial N to N in the protozoal fraction decreased from 45 to 40% in the first sheep, but increased from 35 to 39% in the second; as a consequence, there was a very close relationship (r2 = 0.95) between this parameter and rumen ammonia recycling. Treatment decreased protozoal turnover time in the first sheep, but increased it in the second sheep; this effect may have been due to an increase in lysis of protozoa in the first sheep and a decrease in lysis in the second. Solutes mixed throughout the rumen in from half to one hour.
Growth and yield response of barley and chickpea to water stress under three environments in southeast Queensland. III. Water use efficiency, transpiration efficiency and soil evaporation
Authors: Thoma s , Fukai S
Published: November 2004

Two cultivars of barley and one cultivar of chickpea were grown in both well-watered and water stress conditions in three experiments. Water use efficiency (biomass produced per unit evapotranspiration) was lower in chickpea than in barley, and between two barley cultivars it was higher in early-maturing Corvette than in late-maturing Triumph. These differences in water use efficiency were mostly related to the differences in transpiration efficiency (biomass produced per unit transpiration). The latter appeared to reflect the differences in biomass production under well-watered conditions, as similar differences were found in light use efficiency (biomass produced per unit of photosynthetically active radiation intercepted) among the three crops. Transpiration efficiency was inversely related to vapour pressure deficit of the air. In three experiments soil evaporation accounted for about 55% and 10-30% of total water use for chickpea and barley respectively during observation periods, when rainfall was excluded from the plots. Slow canopy development of chickpea was a reason for such a high proportion of soil evaporation, and this contributed to its lower water use efficiency compared to barley. The amount of radiation transmitted to the soil surface appeared to be an important factor determining soil evaporation, even when soil water was not fully available and limiting soil evaporation.
Economic values of traits for pig improvement. II. Estimates for New Zealand conditions
Authors: Skorupski MT , Garrick DJ , Blair HT , Smith WC
Published: November 2004

A computer model simulating life cycle production of a breeding sow and growth performance of her offspring was used to estimate economic values of reproduction and growth performance traits. The model simulated digestion and metabolism of dietary nitrogen in growing pigs (20 to 85 kg), based on the linear/plateau relationship between daily protein deposition and digestible energy intake. Economic values (EVs) of reproduction and growth performance traits were calculated by simulating effects of genetic changes in several biological components, in a farrow-to-finish production system, assuming ad libitum feeding. Results demonstrated that economic values of traits depended on the average genetic merit in the pig herd and its interaction with the management circumstances (level of feeding, nature of the diet, life cycle length) of the production system.
Intercomparing residuals to find outliers in randomized blocks
Authors: Basford KE , Tukey JW
Published: November 2004

The results of experiments laid out in a randomized complete block often appear to contain one or more unusual values. Techniques for detecting such exotic values, understanding of alternative descriptions of exoticity, one or the other of which applies rather often, leading to what might be done when exotic values are detected, can all be of practical use. This study was designed to investigate such a two-way data set: (a) by using for detection the combination of a median polish to highlight unusual values and an analysis on its residuals that is guided by the order statistic medians from a unit half-Gaussian distribution, (b) by exploring an alternate analysis on a logarithmic scale, and (c) by either Winsorizing or applying missing-value techniques to those values found to be exotic. It details the processes and the ways in which the results may be interpreted by application to data from an experiment conducted by the Rubber Research Institute in Malaysia. This article provides a concise practical tool for the investigation of such data, leading into more appropriate statistical analysis.
Inconsistent transmission of banana bunchy top virus in micropropagated bananas and its implication for germplasm screening
Authors: Thomas JE , Smith MK , Kessling AF , Hamill SD
Published: November 2004

Banana bunchy top virus (BBTV) was readily transmitted through tissue culture in banana (Musa sp.) cv. Lady finger (AAB) and Cavendish cv. Williams (AAA). Lines derived from infected and healthy field plants had similar in vitro multiplication rates. BBTV-infected in vitro cultures displayed symptoms of stunting, leaf curling, chlorotic and green flecks, and poor root growth. Symptoms became milder with time, and were often difficult to discern in older, rapidly multiplying cultures. A triple antibody sandwich ELISA using polyclonal and monoclonal antibodies was very efficient for detecting BBTV in vitro. Symptomless, ELISA-negative plants arose in 10 out of 11 lines derived from BBTV-infected field plants and first appeared after 9 months continuous in vitro culture at a constant 28�C. Meristem tip culture or heat therapy was not used. These plants remained symptomless and ELISA-negative after planting out in the glasshouse (individual plants checked for up to 16 months). The implications of this inconsistent transmission of BBTV for germplasm indexing and exchange are discussed.
Corrigendum - Genetic parameters for terminal sires estimated using data of progeny from Border Leicester × Merino ewes
Authors: Kenney PA , Goddard ME , Thatcher LP
Published: November 2004

Three and a half thousand lambs from Border Leicester x Merino ewes mated to 133 sires from five Poll Dorset, one White Suffolk, one Siromt, two Meridale and four Merino studs were slaughtered, their carcasses halved and one side divided into six primals. Subcutaneous fat was dissected from all six primals, and bone from only the three rear primals. There were four slaughter groups: average slaughter weights of 30 and 35 kg for ewes and 35 and 45 kg for cryptorchids. Heritabilities and phenotypic and genetic correlations for all traits measured (>50) are published in an appendix. Where comparisons were available, estimates were similar to those for purebred animals. Genetic parameters for various assessments of fat were similar except for channel and omental fat. The GR fat depth was the best predictor for total subcutaneous fat, cannon bone length for total bone, and eye muscle area for total soft tissue. Carcass weight and GR appear to be the most important measurements for use in selection for breeding of sires for the prime lamb industry. Slaughter weight and fat depth at the C site could be used as suitable alternatives on live animals. Production of lean meat is not likely to be increased greatly by including measurements other than liveweight and GR in a selection index. Of the other measurements bone length and eye muscle measurements showed most promise.
Least-squares estimation of diet composition from n-alkanes in herbage and faeces using matrix mathematics
Authors: Newman JA , Thompson WA , Penning PD , Mayes RW
Published: November 2004

It is possible to estimate diet composition from an analysis of n-alkanes in the faeces of ruminant animals. For instance, to estimate the proportion of two species in a diet, two equations are constructed using the known concentrations of two different n-alkanes in the herbage and in the animal's faeces. These two equations are solved for the two unknown quantities of the diet components. Two problems exist with this method. First, it is often the case that we have estimated concentrations of more than two different n-alkanes. This can lead to a problem in deciding which two n-alkanes to use to construct the simultaneous equations. The choice of this pair of n-alkanes is arbitrary in its selection and wasteful of other useful information. The second problem is that sometimes the solution to the simultaneous equations yields nonsensical answers, such as a negative proportion of one species in the diet. In addition to making it difficult to estimate dietary proportions, estimating digestibility becomes impossible. In this paper, we present a technique which provides an estimate of the dietary proportions. This estimate uses information on all the n-alkanes available, and it has a very desirable property of being a least squares estimate. We also present a method for determining the least squares estimate subject to the constraint that all proportions must be non-negative. We provide examples for estimating the proportions of grass and clover in the diet of sheep and the digestibility of those diets.
Pathogenic variation in Australian isolates of Mycosphaerella graminicola
Authors: Ballantyne B , Thomson F
Published: November 2004

Seven isolates of Mycosphaerella graminicola gave a range of infection patterns when inoculated onto 20 wheat testers in glasshouse tests. Linear modelling and the biplot technique indicated host-pathogen interaction, hence evidence for physiologic specialization. Two isolates from Western Australia (WA) gave only limited disease on the cultivar Egret which is field resistant in WA. The cvv. Heron and Robin which are related to each other and to Egret also showed limited disease with the WA isolates and with certain NSW cultures. Five New South Wales (NSW) isolates produced moderate to severe infection on this cultivar which is field susceptible in NSW. Among the bread wheats used as sources of resistance in southern NSW only one, M1696, remained healthy with all isolates; nine other lines developed little disease with most isolates but more infection with other isolates, especially two isolates isolated from the field in severe epidemics. There was agreement between replicates within and between experiments. The relevance of these findings to breeding programs is discussed.
Isolation and selection of bacteria and yeasts antagonistic to preharvest infection of avocado by Colletotrichum gloeosporioides
Authors: Stirling AM , Coates LM , Pegg KG , Hayward AC
Published: November 2004

Bacteria and yeasts were isolated from leaves, flowers and fruit of avocado trees that had not been sprayed with pesticides for several years. Of the 1050 microorganisms isolated, 37% inhibited mycelial growth of Colletotrichum gloeosporioides on potato dextrose agar. Many of these organisms also significantly reduced spore germination of the fungus on cellophane overlaying weak sugars agar and a greater proportion of yeasts than bacteria were more effective. Some bacteria and yeasts also reduced spore germination of the pathogen on avocado leaf disks. The predominant group of suppressive bacteria was Bacillus spp., and the antagonistic yeasts included Aureobasidium spp. and a variety of pink and white colony types. Antibiotic resistant isolates of Bacillus, carbendazim resistant isolates of two yeasts and an Aureobasidium sp. were sprayed on avocado leaves and survived for at least 2 months on the phylloplane. On the basis of performance in these tests, isolates with biocontrol and colonization potential were selected and tested for their capacity to provide disease control on fruit. In repeated tests, several bacteria and yeasts consistently reduced lesion development and lesion size on detached avocado fruit when applied prior to inoculating fruit with the pathogen.
Estimates of food intake using slow-release devices and carcass composition of Angus cows from a control line and a line selected for increasing yearling weight
Authors: Morris CA , Cullen NG
Published: November 2004

Data from cows in two Angus lines, established in 1971 and comprising a yearling weight selection line (AS1) and its contemporary control (ACO), were recorded over three periods per year to estimate food intakes at pasture in a 3-year study begun in 1991. In each period, daily organic matter intake (DOMI) was estimated using chromic oxide slow-release devices. In total, 126 cows were included over an average of 2.6 periods each. Forty-six cows were slaughtered after weaning to determine if there were any line differences in body composition. The repeatability of DOMI estimates was 0.46�0.04, whilst the value between cows was 0.24�0.05. The AS1 cows were 15.0% heavier and ate 10.5% more than the ACO cows (P < 0.001). Estimated intakes per unit body weight or per unit metabolic body weight did not differ between lines. Adjusted calf weaning weights at 6 months of age per unit DOMI of the dam were 20.2 and 19.4 kg/kg respectively ( P < 0.05), a 4.1% increase by the AS1 line. The AS1 cows had 17.7% (P < 0.001) heavier carcasses than ACO cows. When adjusted to equal hot carcass weight on a log-log basis, AS1 cows had significantly more bone and less fat ( P < 0.01) than ACO cows. Kidney weights, but not heart or liver weights, were significantly greater for AS1 cows than for ACO cows (P < 0.01) when adjusted to a constant empty live weight. It was concluded that the cow-calf pairs in the AS1 line had a 4% greater calf weaning weight per unit of DOMI by cows than those in the ACO line, and differences were associated with cows which had relatively larger kidneys, more % bone and less % carcass fat soon after weaning.
An in vitro perfusion method to estimate rates of plant residue breakdown and associated nutrient release
Authors: Lefroy RDB , Konboon Y , Blair GJ
Published: November 2004

Procedures are required to screen leaf litter and crop residues to estimate breakdown rates and to examine the effects of chemical treatment or soil biota on decomposition rates. A simple, cheap and effective apparatus has been developed, utilizing a hospital drip bag and administration set, and the results from this apparatus compared with those from a more elaborate glass apparatus. The C release rate and total C release from barrel medic (Medicago truncatula) hay were found to be the same from both systems over 42 days. The UNE (University of New England) in vitro perfusion apparatus is cheap enough to make and simple enough to operate for sufficient sets to be run to allow statistically valid comparisons between residues or residue treatments. The C and nutrient release from wheat straw, chickpea trash, barrel medic hay and two tree legumes, Flemingia macrophylla and Albizia chinensis, were studied over 84 days. Carbon release was highest from chickpea and medic. Carbon release from Albizia was lower than from medic despite it having a lower C:N ratio. Nutrient release rate differed between nutrients and between the residues.
Amelioration of coarse textured acidic soils used for macadamia production. I. Tree growth, yield and leaf nutrient composition
Authors: Stephenson RA , Aitken RL , Gallagher EC , Moody PW
Published: November 2004

Macadamia growers have responded to increasing soil acidity in plantations by applying ameliorants, but optimum pH for production has not been identified. The effects of lime applications on the growth, yield and leaf composition of macadamia (Macadamia integrifolia Maiden and Betch) trees were investigated at each of two sites (Pomona and Cootharaba) with acidic sandy soils in south-east Queensland. Trees at the Pomona site had been established for 6 years whereas, at Cootharaba, the trees had been recently planted. The effects of annual applications of nitrogen and nitrogen plus lime were also studied at the Cootharaba site. Tree parameters and soil properties were monitored each year for 5 years after treatment application in 1988. Treatments resulted in pH (water) values ranging from 4.6 to 7.5 and 4.3 to 6.5 at the Pomona and Cootharaba sites, respectively. with a concomitant range in soil Ca and A1 levels. Despite the wide range in soil properties, lime had no significant (P < 0.05) effect on nut-in-shell yield in any year, and the results suggest that macadamia is relatively tolerant of soil acidity. However, yields from treatments with pH values greater than 5.5 tended to be lower than those with more acidic pH values, suggesting that overliming may adversely affect long-term productivity. High lime rates also resulted in a marked reduction in the number of proteoid roots. At the Cootharaba site, nitrogen treatments significantly (P < 0.05) increased nut-in-shell yield despite the juvenile growth stage of the trees precluding nut yield until the 1993 season. Although lime applications at the Cootharaba site resulted in some increase in leaf Ca concentrations, treatments at the Pomona site, with older trees, had little effect on leaf nutrient composition.
The animal: options for managing intake
Authors: Dynes RA
Published: November 2004

Managing voluntary feed intake of grazing animals is essential to maximise returns and to meet market specifications. Restricting nutrient intake is successfully achieved by controlled grazing management techniques and with feed additive use in intensive feeding systems. Increasing feed intake in the long-term will be a greater challenge to research. There is considerable potential with existing genotypes of sheep to increase intake, because intake appears to be limited by a lack of hunger drive rather than by limitations due to tissue energy transactions or gut load. Increasing voluntary feed intake will be successful if we can increase the hunger drive within the brain. Increasing the hunger drive may be achieved by decreasing the metabolic satiety signal arising from tissue transactions, by reducing the magnitude of the satiety signals arising from the gastrointestinal tract or by modifying neurotransmitters within the brain to enhance the hunger drive.
RAPD-PCR identification of Verticillium dahliae isolates with differential pathogenicity on cotton
Authors: Ramsay JR , Multani DS , Lyon BR
Published: November 2004

Strains of the fungal wilt pathogen Verticillium dahliae cause considerable economic losses in field crops throughout the world. We have investigated the use of molecular genetic techniques for the identification and classification of strains infecting cotton plants (Gossypium spp.) in the major production regions of Australia. The amplification, sequencing, and restriction digestion of specific ribosomal DNA sequences proved to be diagnostic for the genus/species, but was incapable of differentiating between individual isolates with quite diverse morphologies or origins. RAPD-PCR analysis using a subset of 13 informative decamer primers, however, did reveal significant differences between the isolates and enabled the genetic similarity of the V. dahliae strains to be estimated. RAPD-PCR fingerprints were shown to be reproducible following in planta culture of V. dahliae isolates and could be a valuable tool for the identification and epidemiological study of fungal populations. Although fungal isolates were found to elicit a range of reactions during pathogenicity testing on 5 cotton cultivars, comparison of the RAPD-PCR banding patterns did not suggest a strong correlation between molecular genetic and virulence characteristics.
Nitrogen fertiliser residues for wheat cropping in subtropical Australia
Authors: Strong WM , Dalal RC , Weston EJ , Cooper JE , Lehane KJ , King AJ
Published: November 2004

Applied nitrogen (N) recovered by fertilised wheat and by successive wheat crops in a 4-crop sequence (1987-90) was studied by applying 15N-depleted ammonium nitrate (0, 2.5, and 7.5 g/m2) to a Vertisol in the summer-dominant rainfall region of northern Australia. Recoveries of applied N by each of the 4 crops in order of cropping sequence were 60.3� 4.2, 4.4 � 2.3, 1 . 3 � 0.49, and 0- 8 � 0.56%, there being no effect of 2 tillage treatments, conventional tillage (CT) and no till (NT), on uptake of applied N. There was very low recovery of residual fertiliser N after the first wheat crop was harvested; usually <lo% of the applied N was recovered. There was evidence of a substantial N carryover benefit where fertiliser N (7.5 g/m2) was applied in 1987, but not when applied at the same rate in 1988 or 1989. Carryover effect was shown only when fertiliser N was applied after a long fallow when antecedent NOT-N was already high (100-150 v. 30-55 kg/ha with a normal summer fallow). Carryover of subsoil NO3 -N from a single N fertiliser application to the crop, as occurred with application in 1987, will provide useful buffer for declining N supplies of soil N in seasons of good crop response. Routine application of N at moderate rates (<75 kg/ha) provides an effective means of supplementing declining soil N reserves for winter cereals in this region of unreliable rainfall.