Fibre Transfer in Merino Ewes Mated with Damara, Merino or Dorper Rams in Central Western Queensland

Considerable concern has been expressed by the Australian wool industry regarding the contamination of the clip with coloured or kempy fibres from imported breeds of sheep. As part of the evaluation of imported sheep meat breeds in western Queensland, a study is examining fibre growth and transfer of fibres and the potential to cause physical contamination of Merino fleeces. The breeds of concern in this study are the Damara, a fat-tailed breed with a hairy, coloured fleece and the Dorper which has both pigmented fibres and a kempy fleece which is shed cyclically. Three groups of Merino 27 ewes were mated to Merino, Damara and Dorper rams respectively and fibre transfer to the Merino ewes during mating, from lambing to weaning and during grazing, assessed. Both a direct field method and a laboratory method (Hatcher 1995) are being used. Those measured by direct count were measured immediately after joining and 2, 4 and 8 weeks subsequently. and the other ewes were shorn and sampled and measured in the laboratory using the dark fibre detector. This paper presents preliminary findings of those ewes monitored by the direct field method. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia.

Remodelage neuronal de la cicatrice cardiaque suite à un infarctus du myocarde

Suite à un infarctus du myocarde, la formation d’une cicatrice, nommée fibrose de réparation, représente un processus adaptatif et essentiel empêchant la rupture du myocarde. La cicatrice est constituée de myofibroblastes, de cellules vasculaires, de fibres sympathiques ainsi que de cellules souches neuronales cardiaques exprimant la nestine. Une perturbation au niveau de ces constituants cellulaires résulte en une formation maladaptative de la cicatrice et éventuellement, une diminution de la fonction cardiaque. La compréhension des événements cellulaires ainsi que les mécanismes sous-jacents participant à cette fibrose est alors d’une importance primordiale. Cette thèse est axée sur l’identification du rôle du système sympathique et des cellules souches neuronales cardiaques exprimant la nestine dans la formation de la cicatrice ainsi que leur interaction potentielle. Nos travaux examinent l’hypothèse que les cellules souches neuronales exprimant la nestine sont endogènes au cœur et que suite à un dommage ischémique, elles contribuent à la réponse angiogénique et à la réinnervation sympathique du tissu lésé. Les cellules souches neuronales exprimant la nestine sont retrouvées dans les cœurs de différentes espèces incluant le cœur infarci humain. Elles sont résidentes dans le cœur, proviennent de la crête neurale lors du développement et sont intercalées entre les cardiomyocytes n’exprimant pas la nestine. Suite à leur isolation de cœurs infarcis de rats, les cellules souches neuronales cardiaques prolifèrent sous forme de neurosphères et, dans des conditions appropriées in vitro, se différencient en neurones exprimant le neurofilament-M. Suite à un infarctus du myocarde, les niveaux de l’ARNm de nestine sont significativement augmentés au niveau de la région infarcie et non-infarcie. Nos résultats suggèrent que cette augmentation de l’expression de nestine dans la cicatrice reflète en partie la migration des cellules souches neuronales cardiaques exprimant la nestine de la région non-infarcie vers la région infarcie. Lors de la fibrose de réparation, ces cellules représentent un substrat cellulaire pour la formation de nouveaux vaisseaux et contribuent aussi à la croissance des fibres sympathiques dans la région infarcie. Finalement, nous démontrons que la formation de la cicatrice est associée à une innervation sympathique de la région infarcie et péri-infarcie. De plus, les fibres sympathiques présentes dans la région infarcie sont observées à proximité de vaisseaux de petits calibres. Ces données suggèrent indirectement que l’innervation de la cicatrice par les fibres sympathiques peut jouer un rôle dans la réponse angiogénique suite à un infarctus du myocarde. Suite à l’administration du corticostéroïde dexaméthasone, nous détectons un amincissement de la cicatrice, associé à une réduction significative des fibres sympathiques exprimant le neurofilament-M dans la région infarcie et péri-infarcie. La diminution de la densité de ces fibres par le dexaméthasone peut être reliée à une diminution de la prolifération des myofibroblastes et de la production de l’ARNm du facteur neurotrophique nerve growth factor.

Mohair research update 18 : the importance of the live weight of Angora goats on husbandry and production

The live weight of farm animals is strongly associated with production, profitability, management requirements and animal survival (Table 1). The mature live weight of farm animals and of goats is positively associated with their potential to grow rapidly. Live weight is directly related to the nutrient requirements of goats, irrespective of their productive state.

For Angora goats in particular, live weight is associated with mohair production and mohair fibre diameter, age at puberty, reproductive performance and ovulation rate, carcass attributes, meat production and sale value at the end of their productive life. Live weight also affects the timing of the eruption of incisor teeth.

Use of part records in Merino breeding programs - The inheritance of wool growth and fibre traits during different times of the year to determine their value in Merino breeding programs

Fibre diameter can vary dramatically along a wool staple, especially in the Mediterranean environment of southern Australia with its dry summers and abundance of green feed in spring. Other research results have shown a very low phenotypic correlation between fibre diameter grown between seasons. Many breeders use short staples to measure fibre diameter for breeding purposes and also to promote animals for sale. The effectiveness of this practice is determined by the relative response to selection by measuring fibre traits on a full 12 months wool staple as compared to measuring them only on part of a staple. If a high genetic correlation exists between the part record and the full record, then using part records may be acceptable to identify genetically superior animals. No information is available on the effectiveness of part records. This paper investigated whether wool growth and fibre diameter traits of Merino wool grown at different times of the year in a Mediterranean environment, are genetically the same trait, respectively. The work was carried out on about 7 dyebanded wool sections/animal.year, on ewes from weaning to hogget age, in the Katanning Merino resource flocks over 6 years. Relative clean wool growth of the different sections had very low heritability estimates of less than 0.10, and they were phenotypically and genetically poorly correlated with 6 or 12 months wool growth. This indicates that part record measurement of clean wool growth of these sections will be ineffective as indirect selection criteria to improve wool growth genetically. Staple length growth as measured by the length between dyebands, would be more effective with heritability estimates of between 0.20 and 0.30. However, these measurements were shown to have a low genetic correlation with wool grown for 12 months which implies that these staple length measurements would only be half as efficient as the wool weight for 6 or 12 months to improve total clean wool weight. Heritability estimates of fibre diameter, coefficient of variation of fibre diameter and fibre curvature were relatively high and were genetically and phenotypically highly correlated across sections. High positive phenotypic and genetic correlations were also found between fibre diameter, coefficient of variation of fibre diameter and fibre curvature of the different sections and similar measurements for wool grown over 6 or 12 months. Coefficient of variation of fibre diameter of the sections also had a moderate negative phenotypic and genetic correlation with staple strength of wool staples grown over 6 months indicating that coefficient of variation of fibre diameter of any section would be as good an indirect selection criterion to improve stable strength as coefficient of variation of fibre diameter for wool grown over 6 or 12 months. The results indicate that fibre diameter, coefficient of variation of fibre diameter and fibre curvature of wool grown over short periods of time have virtually the same heritability as that of wool grown over 12 months, and that the genetic correlation between fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part and on full records is very high (rg > 0.85). This indicates that fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part records can be used as selection criteria to improve these traits. However, part records of greasy and clean wool growth would be much less efficient than fleece weight for wool grown over 6 or 12 months because of the low heritability of part records and the low genetic correlation between these traits on part records and on wool grown for 12 months.

Transient analysis of mammalian cell growth in hollow fibre bioreactor

A mathematical model describing the dynamics of mammalian cell growth in hollow fibre bioreactor operated in closed shell mode is developed. Mammalian cells are assumed to grow as an expanding biofilm in the extra-capillary space surrounding the fibre. Diffusion is assumed to be the dominant process in the radial direction while axial convection dominates in the lumen of the bioreactor. The transient simulation results show that steep gradients in the cell number are possible under the condition of substrate limitation. The precise conditions which result in nonuniform growth of cells along the length of the bioreactor are delineated. The effect of various operating conditions, such as substrate feed rate, length of the bioreactor and diffusivity of substrate in different regions of the bioreactor, on the bioreactor performance are evaluated in terms of time required to attain the steady-state. The rime of growth is introduced as a measure of effectiveness factor for the bioreactor and is found to be dependent on two parameters, a modified Peclet number and a Thiele modulus. Diffusion, reaction and/or convection control regimes are identified based on these two parameters. The model is further extended to include dual substrate growth limitations, and the relative growth limiting characteristics of two substrates are evaluated. (C) 1997 Elsevier Science Ltd.

Frequency of shearing increases growth of fibre and changes objective and subjective attributes of Angora goat fleeces

The impact of genotype and of frequency and timing of shearing, on mohair attributes and production of modern Angora goats was studied. Goats in the southern hemisphere grazed pastures between February 2004 and 2006. There were seven shearing treatments by three genetic strains with four or eight replicates of individual goats. Treatments were: three different 6-month shearing intervals and two of 12-month shearing intervals with different months of shearing, a 7-month winter shearing interval and a 3-month shearing interval. Genetic strain was based on sire line: 1·0 South African; 1·0 Texan; and Mixed 0·5 South African and 0·5 Texan. Annual greasy mohair production was 5·08 kg, and average clean fleece production was 4·37 kg. The Angora goats produced an annual clean fleece equivalent to 0·122 of their mean fleece-free live weight which was equal to 0·34 g/kg/day. Measurements were analysed over the period of spring 2004 shearing to spring 2005 shearing, excluding the June–December shearing treatment. Increased frequency of shearing increased fleece growth and affected 13 objective and subjective attributes of mohair that were evaluated including clean washing yield, fibre diameter and fibre diameter variation, incidence of medullated fibres, staple length, fibre curvature, crimp frequency, style, staple definition, staple fibre entanglement and staple tip shape. The direction of these effects were generally favourable and for most attributes the magnitude of the response was linear and commercially important. Each additional shearing resulted in an additional 149 g of clean mohair representing 0·034 of the annual clean mohair production. This increase was associated with a 0·6 cm increase in staple length and 0·32 μm increase in mean fibre diameter. In conclusion, Angora goats shorn less frequently grew less mohair that was more likely to be entangled in spring. Managers of Angora goats should take note of these findings.

Influence of energy and polymer-escapsulated methionine supplements on mohair growth and fibre diameter of Angora goats fed at maintenance

We studied the fleece production of Angora wether goats provided with energy, to maintain liveweight, and polymer-encapsulated methionine while they were fed on poor quality roughage rations in early summer. Forty goats (mean fleece-free liveweight 28.5 kg) were randomly allotted to 5 treatments and housed individually for 12 weeks. The treatments were: control, fed to lose 5 kg liveweight; M, fed to maintain liveweight; and 3 maintenance rations with either 0.5, 1 or 2 g day-1 of polymer-encapsulated methionine. The basal ration was oaten chaff (56.8% digestible dry matter) and all maintenance- fed goats received a supplement of 150 g day- 1 gristed barley. Goats required an estimated 267 kJ ME kg-0.75 day-1 to maintain liveweight. Goats fed the control diet grew less mohair (P<0.05) with reduced mean fibre diameter (P< 0.05) than maintenance-fed goats (4.9 g day-1, 30.0 pm compared with 5.8 g day-1, 31.9 pm). For maintenance-fed animals, the addition of 1 g day- methionine (0.15% of dry matter intake) increased mohair growth by 0.8g day-1 (P<0.075). Feeding barley to prevent liveweight loss and feeding polymer-encapsulated methionine at maintenance is unlikely to result in economic responses in mohair production of goats grazing low quality summer pastures

Effect of sugar beet pulp fibre fractions on growth performance, fecal digestibility and digestive physiology in rabbits around weaning

The present study investigated the effect of the different fibre components of sugar beet pulp (SBP) on growth performance and some digestive traits. Four semi-synthetic diets were formulated with similar NDF (33% DM) and protein (16% DM) level. Control diet was formulated to contain the lowest level of soluble fibre (3% DM) and SBP diet the highest (9%). The soluble (pectins) and insoluble fractions of SBP were studied in other two diets (Pectin and InsSBP diets). A total of 136 weanling rabbits (25 d of age) was housed individually, randomly assigned to 4 experimental groups, and fed ad libitum with the experimental diets during 10 days after weaning. The type of diet did not affect growth rate and stomach pH. Animals fed with SBP diet showed higher DM and NDF digestibility (4 and 83%, respectively), gain:feed ratio (13%), cecal and total tract weight (13 and 9%) and ileal viscosity (148%) than rabbits fed the Control diet, but lower cecal pH (9%). Pectin diet increased ileal viscosity and decreased the weight of stomach content with respect to SBP diet. Rabbits fed InsSBP diet showed similar results to SBP diet but lower ileal viscosity and cecal pH than those fed Pectin diet. In conclusion, SBP and their soluble and insoluble fractions are well digested in young rabbits. However the soluble and insoluble fibre of SBP produce different effects in the gastrointestinal tract.

Evaluation of silk sericin as a biomaterial: In vitro growth of human corneal limbal epithelial cells on Bombyx mori sericin membranes

Sericin and fibroin are the two major proteins in the silk fibre produced by the domesticated silkworm, Bombyx mori. Fibroin has been extensively investigated as a biomaterial. We have previously shown that fibroin can function successfully as a substratum for growing cells of the eye. Sericin has been so far neglected as a biomaterial because of suspected allergenic activity. However, this misconception has now been dispelled, and sericin’s biocompatibility is currently indisputable. Aiming at promoting sericin as a possible substratum for the growth of corneal cells in order to make tissue-engineered constructs for the restoration of the ocular surface, in this study we investigated the attachment and growth in vitro of human corneal limbal epithelial cells (HLECs) on sericin-based membranes. Sericin was isolated and regenerated from the silkworm cocoons by an aqueous procedure, manufactured into membranes, and characterized (mechanical properties, structural analysis, contact angles). Primary cell cultures from two donors were established in serum-supplemented media in the presence of murine feeder cells. Membranes made of sericin and fibroin-sericin blends were assessed in vitro as substrata for HLECs in a serum-free medium, in a cell attachment assay and in a 3-day cell growth experiment. While the mechanical characteristics of sericin were found to be inferior to those of fibroin, its ability to enhance the attachment of HLECs was significantly superior to fibroin, as revealed by the PicoGreen® assay. Evidence was also obtained that cells can grow and differentiate on these substrata.

Selecting hardwood taxa for wood and fibre production in Queensland's subtropics.

Optimal matching of species to sites is required for a sustainable hardwood plantation industry in the subtropics. This paper reports the performance and adaptation of 60 taxa (species, provenances and hybrids) across two rainfall zones and a range of soil types in southern Queensland. Specifically, performance of taxa is compared across five replicated taxon–site matching trials at age 6 y. Three trials are in a 1000-mm y–1 rainfall zone of the Wide Bay region near Miriam Vale and two in a drier (about 750 mm y–1) rainfall zone near Kingaroy in the South Burnett region. In the higher-rainfall zone, the taxa with the fastest growth in the three trials at age 6 y were Corymbia citriodora subsp. variegata Woondum provenance, which ranked 1st, 6th and 5th respectively; E. longirostrata Coominglah provenance, ranked 3rd, 2nd and 3rd; and two sources of E. grandis, Copperlode provenance (ranked 4th and 1st) and SAPPI seed orchard (ranked 6th and 4th), which were planted in only two of the three trials. Similarly, in the lower-rainfall zone, E. grandis and its hybrids appear promising from the 6-y growth data., This excellent early growth, however, has not continued in either rainfall zone, with these taxa, 8 y after planting, now showing signs of stress and mortality. Based on trial results in these two rainfall zones, the taxon that appears the most promising for sustainable plantation development with high average annual volume index values and low incidence of borer attack is Corymbia citriodora subsp. variegata (6.7 m³ ha–1). Eucalyptus grandis and E. longirostrata both have better average annual volume indexes (8.2 m³ ha–1 and 7.4 m³ ha–1 respectively) but are very susceptible to borer attack. The current and long-term productivity and sustainability of plantation forestry in these rainfall zones is discussed. Further, the implications of predicted climate change (particularly reduced rainfall) for growing trees for fibre production and carbon sequestration are explored.

Improving on-farm cotton root growth and functioning under limited water

The objectives of this project over a 3 years study period are: 1) validation and on-farm adoption of improved root growth and functioning for managing cotton production under limited water and nitrogen nutrition; and 2) Delivering improved understanding of enhancing root growth and functioning to about 50% cotton growers in the regions leading towards a better adaptation to future climate driven challenges, particularly limited water availability in Queensland and New South Wales. The research is expected to be supported through cash and/or in-kind contributions by CRDC and Agri-Science Queensland (DEEDI).