6,082 research outputs found
Composition and distribution of the peracarid crustacean fauna along a latitudinal transect off Victoria Land (Ross Sea, Antarctica) with special emphasis on the Cumacea
No full textThe following study was the first to describe composition and structure of the peracarid fauna systematically along a latitudinal transect off Victoria Land (Ross Sea, Antarctica). During the 19th Antarctic expedition of the Italian research vessel “Italica” in February 2004, macrobenthic samples were collected by means of a Rauschert dredge with a mesh size of 500 m at depths between 85 and 515 m. The composition of peracarid crustaceans, especially Cumacea was investigated. Peracarida contributed 63% to the total abundance of the fauna. The peracarid samples were dominated by amphipods (66%), whereas cumaceans were represented with 7%. Previously, only 13 cumacean species were known, now the number of species recorded from the Ross Sea increased to 34. Thus, the cumacean fauna of the Ross Sea, which was regarded as the poorest in terms of species richness, has to be considered as equivalent to that of other high Antarctic areas. Most important cumacean families concerning abundance and species richness were Leuconidae, Nannastacidae, and Diastylidae. Cumacean diversity was lowest at the northernmost area (Cape Adare). At the area off Coulman Island, which is characterized by muddy sediment, diversity was highest. Diversity and species number were higher at the deeper stations and abundance increased with latitude. A review of the bathymetric distribution of the Cumacea from the Ross Sea reveals that most species distribute across the Antarctic continental shelf and slope. So far, only few deep-sea records justify the assumption of a shallow-water–deep-sea relationship in some species of Ross Sea Cumacea, which is discussed from an evolutionary point of view
Effect of dietary methionine level on productivity and carcass characteristics of ross 308 broiler chickens
No full textThesis (M. Sc. Agriculture (Animal Production)) -- University of Limpopo, 2019Two experiments were conducted to determine the effect of dietary methionine level on productivity and carcass characteristics of Ross 308 broiler chickens. In each experiment, the diets were isocaloric and isonitrogenous but with different dietary methionine levels. Five diets were formulated to contain dietary methionine levels of 4, 5, 6, 8 or 9g/kg DM. The first experiment commenced with 300 unsexed Ross 308 broiler chickens with initial average live weights of 42 ± 2g per chicken. The chickens were randomly assigned to five treatments with five replications, resulting in 25-floor pens with 12 chickens per replicate. The second experiment commenced with 150 male Ross 308 broiler chickens with initial average live weight of 637 ± 12g per chicken. The chickens were randomly assigned to five treatments with three replications, resulting in 15-floor pens with 10 chickens per replicate. A complete randomized design was used in each experiment. Data was analysed using the General Linear Model (GLM) procedures of the statistical analysis of variance, Version 9.3.1 software program. Where there were significant differences, mean separation was done using the Tukey test at the 5% level of significance. A quadratic regression model was used to determine the optimal productivity of the chickens while a linear model was used to determine the relationships between dietary methionine level and responses by the chickens in the variables measured.
The treatments for the first experiment were UM4 (4g methionine/kg DM), UM5 (5g methionine/kg DM), UM6 (6g methionine/kg DM), UM8 (8g methionine/kg DM) and UM9 (9g methionine/kg DM). Feed intake, growth rate, feed conversion ratio (FCR), metabolisable energy intake and nitrogen retention of unsexed Ross 308 broiler chickens aged one to 21 days were not affected (P>0.05) by dietary methionine level. Similarly, dietary methionine level did not have any effect (P>0.05) on diet crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF) and fat digestibilities in unsexed Ross 308 broiler chickens aged 14 to 21 days. Dietary methionine level did not have any effect on live weights of broiler chickens at 21 days. Live weights of unsexed Ross 308 broiler chickens aged 7 or 14 days were not improved (P>0.05) by increasing dietary methionine level from 4 to 9g/kg DM. Crop, gizzard and small intestine weights and crop, proventriculus and gizzard digesta pH values of unsexed Ross 308 broiler chickens aged 21 days were not affected
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(P>0.05) by dietary methionine level. Similarly, dietary methionine level did not improve (P>0.05) caecum and large intestine lengths of unsexed Ross 308 broiler chickens aged 21 days. However, dietary methionine level affected (P<0.05) dry matter (DM) and ash digestibilities of unsexed Ross 308 broiler chickens aged 14 to 21 days. Proventriculus and large intestine weights, gastrointestinal tract and small intestine lengths of unsexed Ross 308 broiler chickens aged 21 days were improved (P<0.05) by increasing dietary methionine level. In addition, increasing dietary methionine level increased (P<0.05) small and large intestine digesta pH values of broiler chickens aged 21 days. Thus, dry matter digestibility, live weights at day 7 ad 14, caecum length, large intestine length and digesta pH were optimized at different dietary methionine levels of 7.26, 5.29, 4.99, 6.80, 4.84 and 6.37g/kg DM feed, respectively.
The treatments for the second experiment were MM4 (4g methionine/kg DM), MM5 (5g methionine/kg DM), MM6 (6g methionine/kg DM), MM8 (8g methionine/kg DM) and MM9 (9g methionine/kg DM). Dietary methionine level did not have effect (P>0.05) on feed intake of male Ross 308 broiler chickens aged 6 weeks. However, dietary methionine level improved (P0.05) by dietary methionine level. However, live weights of male Ross 308 broiler chickens aged 35 and 42 days were affected (P<0.05) by dietary methionine level. Similarly, dietary methionine level affected (P<0.05) DM, CP, ADF, NDF, fat and ash digestibilities of male Ross 308 broiler chickens aged 35 to 42 days. Thus, dietary methionine levels of 6.93, 7.70, 6.85 and 11.27g/kg DM optimized dry matter, CP and fat digestibilities, and live weight of male broiler chickens aged 42 days.
Dietary methionine level did not affect (P>0.05) FCR, growth rate and metabolisable energy intakes of male Ross 308 broiler chickens. Increasing dietary methionine level from 4 to 9g/kg DM improved (P0.05) on proventriculus, gizzard, caecum and large intestine weights, caecum, small and large intestine lengths, and crop, gizzard, caecum and large intestine digesta pH values of male Ross 308 broiler chickens aged 42 days. Crop and small
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intestine weights and gastrointestinal tract lengths of male Ross 308 broiler chickens aged 42 days were improved (P<0.05) by dietary methionine level. Similarly, dietary methionine level affected (P<0.05) proventriculus and small intestine digesta pH values of male Ross 308 broiler chickens aged 42 days. Thus, dietary methionine levels of 6.558 and 7.851g/kg DM optimized broiler chicken crop weight and GIT length.
Dietary methionine level affected (P0.05) by dietary methionine level. However, dietary methionine level affected meat tenderness and juiciness. Thus, dietary methionine levels of 10.09 and 13.32g/kg DM optimized broiler chicken meat tenderness and juiciness.
.National Research Foundation (NRF) and VLIROU
Influence of hosts on the ecology of arboviral transmission: Potential mechanisms influencing dengue, Murray Valley encephalitis, and Ross River virus in Australia
No full textEcological interactions are fundamental to the transmission of infectious disease. Arboviruses are particularly elegant examples, where rich arrays of mechanisms influence transmission between vectors and hosts. Research on host contributions to the ecology of arboviral diseases has been undertaken within multiple subdisciplines, but significant gaps in knowledge remain and multidisciplinary approaches are needed. Through our multidisciplinary review of the literature we have identified five broad areas where hosts may influence the ecology of arboviral transmission: host immunity; cross-protective immunity and antibody-dependent enhancement; host abundance; host diversity; and pathogen spillover and dispersal. Herein we discuss the known and theoretical roles of hosts within these topics and then apply this knowledge to three epidemiologically important mosquito-borne arboviruses that occur in Australia: dengue virus (DENV), Murray Valley encephalitis virus (MVEV), and Ross River virus (RRV). We argue that the underlying mechanisms by which hosts influence arboviral activity are numerous and attempts to delineate these mechanisms further are needed. Investigations that focus on hosts of vector-borne diseases are likely to be rewarding, particularly where the ecology of vectors is relatively well understood. From an applied perspective, enhanced knowledge of host influences upon vector-borne disease transmission is likely to enable better management of disease burden. Finally, we suggest a framework that may be useful to identify and determine host contributions to the ecology of arboviruses
Prioritising options to reduce the process steam consumption of raw sugar mills
No full textLOW WORLD sugar prices are making it increasingly difficult for raw sugar mills to remain competitive, and many milling companies are embarking on new revenue earning opportunities. In almost all new ventures, the energy from bagasse (as steam or cogenerated electricity) or the fibre itself provides an important basis for generating the additional revenue. Integral to increasing the economic viability of such projects is the need to cost-effectively reduce the steam consumed by the factory for sugar manufacture. The Sugar Research Institute has completed a comprehensive study of numerous options to reduce the process steam consumption of factories, and to determine the financial implications of the different options. Process simulation software for evaporators, pans and heaters were integrated with a basic high pressure steam model. For each process steam efficiency option, the effects on boiler load, fuel consumption, and cogeneration output could be accurately assessed for selected steam conditions at the boiler. The outputs from the integrated process model were directly linked to the financial model. For nominated input conditions, the project determined a prioritised list of technically and economically attractive options for reducing the steam consumption of the factory. The analyses were undertaken for three scenarios which include sale of export electricity, sale of surplus steam or sale of surplus bagasse. This paper describes the development of the integrated models and the results for a base case study. The results show a quintuple station is the preferred evaporator configuration for circumstances where the steam on cane is reduced from current levels of approximately 50% on cane to about 40%. To reduce the steam consumption below this level, a sextuple arrangement is preferred. A quadruple set shows inferior results for all steam on cane values. Options for steam on cane to below 30% were found to be technically feasible for cane factories, but these configurations are not likely to be economically justified
Natural history of Ross River virus-induced epidemic polyarthritis.
No full textObjective: To describe the natural history, treatment and cost of Ross River virus-induced epidemic polyarthritis (RRV disease).
Design: Questionnaire-based longitudinal prospective study.
Participants and setting: Patients in the greater Brisbane area, Queensland, diagnosed with RRV disease by their general practitioners based on clinical symptoms and paired serological tests between November 1997 and April 1999.
Main outcome measures: Scores on two validated quality-of-life questionnaires (Clinical Health Assessment Questionnaire and Medical Outcomes Study Short Form 36) were obtained soon after diagnosis and one, two, three, six and 12 months thereafter. Scores were compared between patients diagnosed with RRV disease alone and those with RRV disease plus other conditions.
Results: 67 patients were enrolled. Most patients with RRV disease alone had severe acute symptoms, but followed a consistent path to recovery within three to six months. Other conditions, often chronic rheumatic diseases or depression, were identified in half the cohort; their quality-of-life scores suggested stable chronic illness between six and 12 months after diagnosis. Non-steroidal anti-inflammatory drugs (NSAIDs) were taken by 58% of patients (average use, 7.6 weeks; range, 2–22 weeks). Time off work averaged 1.9 days, and direct cost to the community was estimated as $A1018 per patient.
Conclusions: Symptom duration and frequency of long-term symptoms may have been overestimated by previous studies of RRV disease. Disease persisting six to 12 months after RRV diagnosis was largely attributable to other conditions, highlighting the need to seek other diagnoses in RRV patients with persistent symptoms.Griffith Health FacultyFull Tex
Effects of natuzyme® supplementationon fibre digestion, growth and carcass characteristics of male ross 308 broiler chickens
No full textThesis (M.A. (Agricultural Management) -- University of Limpopo, 2020Two experiments were conducted to determine the effect of natuzyme50® supplementation on fibre digestion, growth and carcass characteristics of Ross 308 broiler chickens aged one to 42 days. The first experiment determined the effect of natuzyme50® supplementation on feed intake, growth and live weight of unsexed Ross 308 broiler chickens aged one to 21 days. Unsexed day old chicks were assigned to 4 different natuzyme50® supplementation levels of 0.0 (UNZ0), 0.75 (UNZ0.75), 1.0 (UNZ1.0) and 1.5 (UNZ1.5) g/kg DM feed, replicated 4 times and each replicate having 10 chicks. A general linear model (SAS, 2008) was used to analyse the data. Ross 308 broiler chickens on a diet supplemented with 1.5g of natuzyme50® per kg DM had higher (P0.05) have any significant effect on growth rate of unsexed Ross 308 broiler chickens aged one to 21 days. Unsexed broiler chickens on a diet supplemented with 1.5g of natuzyme50® per kg DM had higher (P<0.05) live weights than those on a diet not supplemented with natuzyme50® at the age of 21 days
The second experiment determined the effect of natuzyme50® supplementation on feed intake, growth performance and carcass characteristics of male Ross 308 broiler chickens aged 22 to 42 days. The chickens aged 22 days were assigned to 4 natuzyme50® supplementation levels of 0.0 (MNZ0), 0.75 (MNZ0.75), 1.0 (MNZ1.0) and 1.5 (MNZ1.5) g/kg DM feed, replicated 4 times and each replicate having 6 chickens. The diets were isocaloric and isonitrogenous. A general linear model (SAS, 2008) was used to analyse the data obtained. Natuzyme50® supplementation level had no effect (P>0.05) on feed intake of male Ross 308 broiler chickens aged 22 to 42 days. However, natuzyme50® supplementation level had effect (P<0.05) on growth rate of male Ross broiler chickens aged 22-42 days. Male Ross 308 broiler chickens on a diet supplemented with 1.5g of natuzyme50® per kg DM had higher (P<0.05) growth rates than those on a diet supplemented with 1.0g of natuzyme50® per kg DM. However, the significant differences did not extend to birds on a diet not supplemented with natuzyme50®, diets supplemented with 0.75 or 1.5g of natuzyme50® per kg DM which
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showed similar (P>0.05) growth rates. Natuzyme50® supplementation levels used had no effect (P>0.05) on carcass, breast and drumstick weights of male Ross 308 broiler chickens. Natuzyme50® supplementation levels had no effect (P>0.05) on meat juiciness. However, natuzyme50® supplementation improved (P<0.05) meat tenderness and flavour. Increasing natuzyme50® level of supplementation decreased (P<0.05) meat shear force values.
It is concluded that natuzyme50® supplementation improved (P<0.05) meat tenderness and flavour, and reduced meat shear force values of male Ross 308 broiler chickens. However, further studies are recommended to ascertain the current results.Edu-loa
Effect of moringa seed meal supplementation on productivity and carcass characteristics of ross 308 broiler chickens
No full textThesis (MSc. Agriculture (Animal Production)) -- University of Limpopo, 2014Two experiments were conducted to determine the effect of moringa seed meal supplementation on productivity and carcass characteristics of Ross 308 broiler chickens. The first experiment determined the effect of moringa seed meal supplementation on productivity of Ross 308 broiler chickens aged one to 21 days. Two hundred and fifty unsexed day-old Ross 308 broiler chicks were randomly allocated to five dietary treatments, replicated five times, and each replication having 10 chickens. A completely randomized design was used. The chickens were fed on a grower diet supplemented with 0 (M0), 5 (M5), 10 (M10), 15 (M15) and 20 (M20) g of moringa seed meal/bird/day. Moringa seed meal supplementation had no effect (P>0.05) on feed intake, metabolisable energy intake, nitrogen retention, feed conversion ratio and live weight of unsexed Ross 308 broiler chickens. Moringa seed meal supplementation improved (P<0.05) growth rates of unsexed Ross 308 broiler chickens aged one to 21 days. A moringa seed meal supplementation level of 13.3 g/kg DM feed optimized growth rate of Ross 308 broiler chickens aged one to 21 days.
The second experiment determined the effect of moringa seed meal supplementation on productivity and carcass characteristics of female Ross 308 broiler chickens aged 22 to 42 days. The chickens weighing 558 ± 10 g/bird were randomly allocated to five treatments with five replications having 10 birds. The chickens, aged 21 days, were allocated to the treatments in a completely randomized design. The chickens were fed on a grower diet supplemented with 0 (FM0), 5 (FM5), 10 (FM10), 15 (FM15) and 20 (FM20) g of moringa seed meal per kg DM. Moringa seed meal supplementation had no effect (P>0.05) on feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy intake, carcass weight, breast meat weight, abdominal fat pad weight, liver weight, heart weight, thigh weight, meat flavour, juiciness and tenderness of female Ross 308 broiler chickens. However, moringa seed meal supplementation improved (P<0.05) nitrogen retention and gizzard weights of female Ross 308 broiler chickens.
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It was concluded that moringa seed meal supplementation improved growth rate of unsexed Ross 308 broiler chickens aged one to 21 days. Similarly, moringa seed meal supplementation increased nitrogen retention and gizzard weights of female Ross 308 broiler chickens aged 22 to 42 days
Effect of moringa seed meal supplementation on productivity and carcass characterictics of ross 308 broiler chickens
No full textThesis (MSC. Agriculture (Animal Production)) --University of Limpopo, 2014Two experiments were conducted to determine the effect of moringa seed meal supplementation on productivity and carcass characteristics of Ross 308 broiler chickens. The first experiment determined the effect of moringa seed meal supplementation on productivity of Ross 308 broiler chickens aged one to 21 days. Two hundred and fifty unsexed day-old Ross 308 broiler chicks were randomly allocated to five dietary treatments, replicated five times, and each replication having 10 chickens. A completely randomized design was used. The chickens were fed on a grower diet supplemented with 0 (M0), 5 (M5), 10 (M10), 15 (M15) and 20 (M20) g of moringa seed meal/bird/day. Moringa seed meal supplementation had no effect (P>0.05) on feed intake, metabolisable energy intake, nitrogen retention, feed conversion ratio and live weight of unsexed Ross 308 broiler chickens. Moringa seed meal supplementation improved (P<0.05) growth rates of unsexed Ross 308 broiler chickens aged one to 21 days. A moringa seed meal supplementation level of 13.3 g/kg DM feed optimized growth rate of Ross 308 broiler chickens aged one to 21 days.
The second experiment determined the effect of moringa seed meal supplementation on productivity and carcass characteristics of female Ross 308 broiler chickens aged 22 to 42 days. The chickens weighing 558 ± 10 g/bird were randomly allocated to five treatments with five replications having 10 birds. The chickens, aged 21 days, were allocated to the treatments in a completely randomized design. The chickens were fed on a grower diet supplemented with 0 (FM0), 5 (FM5), 10 (FM10), 15 (FM15) and 20 (FM20) g of moringa seed meal per kg DM. Moringa seed meal supplementation had no effect (P>0.05) on feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy intake, carcass weight, breast meat weight, abdominal fat pad weight, liver weight, heart weight, thigh weight, meat flavour, juiciness and tenderness of female Ross 308 broiler chickens. However, moringa seed meal supplementation improved (P<0.05) nitrogen retention and gizzard weights of female Ross 308 broiler chickens.
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It was concluded that moringa seed meal supplementation improved growth rate of unsexed Ross 308 broiler chickens aged one to 21 days. Similarly, moringa seed meal supplementation increased nitrogen retention and gizzard weights of female Ross 308 broiler chickens aged 22 to 42 days
Effect of threonine supplementation level on performance of male ross 308 broiler chickens fed a diet containing cellulase
No full textThesis (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2023An experiment was conducted to evaluate threonine supplementation levels for optimal performance and carcass quality of male Ross 308 broiler chickens aged 22 to 42 days and fed diets mixed with a cellulase enzyme. The diets were isocaloric and isonitrogenous but with different dietary threonine levels. A complete randomized design was used. The treatments were CT4 (4 g of threonine/kg DM), CT5 (5 g of threonine/kg DM), CT6 (6 g of threonine/kg DM) and CT7 (7 g of threonine/kg DM) g of threonine/kg DM. A quadratic type of equation was used to determine dietary threonine levels for optimal performance of the chickens. Dietary threonine levels of 4, 5, 6 or 7 g/kg DM used in the present study had no effect (P>0.05) on feed intake, dry matter (DM) digestibility, live weight, live weight gain, feed conversion ratio (FCR), metabolizable energy (ME) intake and nitrogen retention of male Ross 308 broiler chickens. Dietary threonine levels had no (P>0.05) effect on gut organ digesta pH values, gut organ lengths and gut organ weights of Ross 308 broiler chickens aged 42 days. Dietary threonine level had no effect (P>0.05) on wing weights of the chickens aged 42 days. However, threonine level in the diet affected (P0.05) on meat lightness and yellowness of the chickens. However, threonine level in the diet affected (P0.05) thigh, drumstick, and breast pH values of the chickens. However, dietary threonine level affected (P0.05) meat flavour and juiciness values. However, dietary threonine level affected (P<0.05) meat tenderness, shear force and water holding capacity values of the chickens. A dietary threonine level of 4.78 g per kg DM was calculated to result in optimal meat tenderness of the chickens. The results obtained indicate that threonine levels required for optimal performance of the chickens are within the recommended dietary levels of 4 to 8 g/kg DM for broiler chickens, possibly indicating that diets containing cellulase require additional threonine to utilize additional energy generated
Population Genetics and Photobiont Selectivity in Antarctic Lichens
No full textThis thesis examines population genetic structure and migration indices of an Antarctic endemic lichen Buellia frigida as well as algal selectivity of the lichens Buellia frigida, Umbilicaria aprina and Umbilicaria decussata in the Ross Sea Region of Antarctica. My aim was to determine where current populations may have originated (i.e. ancient or recent introductions to Antarctica) and if the level of algal selectivity potentially affects colonisation.
Chapter 2 reviews historical climate change in Antarctica, particularly in the Ross Sea Region, and introduces the basic characteristics of lichens. It also outlines how molecular analyses of lichen can aid in determining the genetic structure of populations and add to the growing data set which highlights sites in the Ross Sea Region (e.g. Dry Valleys) as glacial refugia.
To examine population differentiation between populations in this region it was necessary to develop polymorphic markers capable of delineating individuals. Chapter 3 focuses on the development of five microsatellite markers for this purpose. The initial data for these microsatellites suggested they were suitable for individual genotyping and characterization of B. frigida population structure being mycobiont specific with a high degree of polymorphism. A method of decreasing inhibiting factors present in lichen cells is also provided.
In Chapter 4 regional genetic differentiation was revealed by an analysis using microsatellite markers developed in Chapter 3 over 11 populations in five regions of the Ross Sea Region. The identification of three populations with high allelic richness and sites of high dispersal indicated three regions as putative refugia (Terra Nova Bay, Dry Valleys and Beardmore Glacier). Terra Nova Bay has not previously been highlighted putatively as refugia. Limited mixing between adjacent geographical areas (such as the Dry Valleys and Ross Island) was identified, with migration likely to be influenced by wind currents.
The photobionts of the lichens Buellia frigida, Umbilicaria aprina and Umbilicaria decussata were examined using ITS rDNA sequence analysis in chapter 5. This identified that over a latitudinal gradient of roughly 10˚, there was a single haplotype present in the majority (>95%) of samples. This haplotype was nearly identical to haplotypes from as far afield as Svalbard showing a consistency in photobiont selection over a very wide geographical range and may be micro-climate specific. Other haplotypes present were specific to single geographical areas, and mutation may play the major role in this.
Collectively, these findings suggest that despite potentially high dispersal of propagules, populations of lichen species in the Ross Dependency show differentiation among locations and are potentially limited in their dispersal to different habitats. This may be the result of high selectivity for the photobiont. I conclude that lichen populations in the Ross Sea Region have originated from ancient, refugial populations rather than being populated via recent dispersal from northern continents. Dispersal within this region is likely to be restricted by ice-covered areas and relichenisation is potentially limited to particular photobiont strains which are suited to the micro-climatic conditions found in this region. In order to minimise the consequences of anthropological disturbance, we recommend the continued protection of areas (e.g. Dry Valleys) housing high lichen and photobiont diversity
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