Seven common marmoset monkeys ('Callithrix jacchus') from a laboratory colony of 17 died over a period of eight months. Death of six of these monkeys was attributed to kidney failure from an oxalate-induced nephropathy. The epidemiology of this outbreak suggested an exogenous source and there was strong evidence that the source was bark and leaves from an 'Eucalyptus viminalis' tree. Branches of this tree were introduced one month before the first death. The branches were removed one month after deaths commenced, but deaths continued for another five months. Urinalysis of all surviving marmosets at 80 and 122 days after initial contact with the 'E viminalis' branches suggested that these monkeys had renal impairment. In the cases described here, the eating behaviour of common marmosets apparently exposed the animals to toxic levels of oxalate in the bark and leaves of an 'E viminalis' tree.

Background: Use of computed tomography (CT) in canine obesity research is limited and accuracy of estimated fat is still questioned. Using latest image analysis programs, previous studies in sheep showed a significant correlation between CT-derived and hot carcass measurements. Hence we tested the method in canine research. Objective: To develop an improved research method to estimate body composition including total body fat, lean tissue and bone in two morphologically diverse breeds of dogs. Design: A whole body scan was performed twice (four weeks apart) on six beagles and six greyhounds using Picker UltraZ 2000 CT scanner. They were sedated to the prone position with fore/hind limbs pointing forward and tails tucked in. The individual CT images were taken at 10 mm interval and edited using latest software (OSIRIX) in diacom format to remove extraneous objects within the image. Images were then converted from 16 bit CT image to 8 bit binary image using Image J and rescaled to 256 greyscales using AutoCAT. Boundaries for fat, lean and bone were set to the scales of 20-130, 131-220, and 221-255 respectively. The AutoCAT program then computed the total weight of fat, lean and bone for each dog. CT-derived total body weight was calculated from the sum of fat, lean and bone. Percentages of fat, lean and bone were also calculated. Pearson correlation analysis between CT-derived and measured total body weight were performed separately in two breeds for two scans (CT1, CT2). Significant differences of fat% between breeds were determined using paired t-test. Outcomes: When CT-derived total body weight was compared with measured total bodyweight, both beagles and greyhounds showed a significant correlation (R²=0.99; P=0.000) for both scans. The method also detected a significant breed difference (P=0.000) in the mean fat% for both scans. Conclusion: The proposed method using latest image analysis software programs showed significant correlation between CT-derived and measured total body weight for both the breeds, and the results were reproducible in two scans. The body compositions of different breeds measured by the CT scan were significantly different. Future studies should compare the proposed method with other existing methods used for detecting body composition such as dual-energy X-ray absorptiometry and deuterium oxide dilution.

We evaluate the pathogenicity of Australian Marek's disease virus (MDV) isolate MPF23 (1985) against the reference strain MPF57 based on pathology, viral load and neurotpathotyping on the basis of clinical signs. Two MDV challenge isolates (MPF57 or MPF23) were administered to unvaccinated SPF layer chicks on day 5 after hatch at three challenge doses (500, 2000 or 8000 plaque forming units (pfu)/chick). Mortality, body weight, immune organ weights, MDV load in peripheral blood lymphocytes (PBL) and clinical signs were measured to 56 days post challenge (dpc). MPF23 was the more pathogenic of the two viruses inducing higher mortality (81% cf. 62%) and incidence of MD lesions (100% cf. 76%). MPF23 induced earlier, more sustained and more severe neurological signs in the period 26-56 days post challenge (dpc). However there were few differences during the period 0-23 dpc used in the neuropathotyping classification under test. The observed pattern during this earlier period classifies both viruses as neuropathotype B consistent with a very virulent pathotype. MDV load in PBL at 7 and 44 dpc did not differ between virus isolates but load at 7 dpc was significantly and negatively associated with time to euthanasia or death. MPF23 appears to be as, or more virulent than MDV strains isolated over the subsequent two decades. The neuropathotyping system developed in the USA did not clearly differentiate between the two isolates under test, however extension of the period of assessment of clinical signs beyond 26 dpc did reveal clear differences.

Background: Previous studies have demonstrated that DHA n-3 FA can reduce obesity by inhibiting adipocyte differentiation. Objective: To investigate the potential of a DHA rich supplement (fish oil; FO) over non DHA (sunflower oil; SF) to reduce weight gain in dogs, when the animals were fed increased dietary energy intakes above maintenance levels (iso-caloric in both groups). The transcriptional, metabolic and phenotypic responses in two dog breeds were assessed. Design: Six beagles and greyhounds were divided equally into two treatment groups (FO and SF). During four weeks, energy intake was increased 20-80% above maintenance level achieved by feeding basal diet (kibble), coconut fat and supplement (FO or SF). Changes to body weight gain (BWG), apparent nutrient digestibility (Dry Matter, Fat, and Gross Energy), red blood cell (RBC) FA levels, White Blood Cell (WBC) inflammatory gene expression levels (HSP90, HSP70 and IL1β) were measured twice: at days 0 and 28. A paired t-test was used to determine significance between time periods, treatments or breeds. Outcomes: BWG in beagles fed FO were significantly higher (P<0.05) than those fed SF. No significant differences in BWG in greyhounds or between breeds were shown. Differences were not seen in apparent nutrient digestibility. HSP90 gene expression was up-regulated in the beagles fed FO (P<0.05), while HSP70 gene down-regulated for both breeds fed SF (P<0.05). A significant breed difference was observed for HSP70 fed SF (P<0.05). RBC EPA levels significantly increased in both breeds fed FO (P<0.05) with no significant difference in DHA levels. Only beagles fed SF showed significant increase in LA, AA (P<0.05). Both breeds fed SF showed significant decrease in GLA (P<0.05). Significant breed differences (P<0.05) were found in RBC FA levels of EPA (FO), LA, GLA and AA (SF). Conclusion: Results from the four weeks trial do not support the potential of DHA n-3 FA to reduce BWG. However, within the same time frame, WBC inflammatory gene expression and RBC FA levels showed differences between treatments and breeds. Therefore breed differences warrant further investigation and future studies should be designed for extended periods with larger datasets.

Unexpected illness and deaths occurred in an experiment to determine the efficacy of four antibiotic feed additives in a necrotic enteritis challenge model. The experimental basal diet was based on a commercial wheatsoy formulation and contained xylanase and phytase at the recommended rates of inclusion. The starter diet in week 1 (days 0-7) was fed as a mash. Adhering to the challenge model, all birds were fed a high protein diet (50 % commercial starter, 50 % fishmeal) in the second week post-hatch (days 7-14). The fishmeal diet was fed as a short cut 5 mm pellet. All diets were mixed at the University of New England, and pelleted using a small scale 'cold' pelleter, with pellet temperatures ranging from 54°C to 81°C. The experimental antibiotics were incorporated into the diets. Challenged and unchallenged negative controls (no antibiotic) were included in the experimental design. Twelve hundred and ninety-six broiler chicks were split into 54 pens of 24 birds (1:1 sex ratio per pen). All birds were fed ad libitum and had free access to water via drinker nipples. On day 9, all birds from challenged treatments were given an oral suspension containing sporulated oocysts of 'Eimeria spp'. whilst unchallenged birds received sterile PBS. As part of the model, challenged treatments were to be inoculated with 'Clostridium perfringens' (scheduled to begin on day 14).

PUFA are important for human and animal health. To our knowledge, previous studies investigating the metabolism of PUFA in dogs have not examined breed differences. The aim of the present study was to evaluate the potential to elongate PUFA in two pure breeds of dogs. Plasma fatty acid composition (%) was measured in dogs during 3 weeks supplementation with flaxseed oil (57 % α-linolenic acid (ALA) and 17 % linolenic acid (LA)) at the rate of 100 ml/kg food following 4 months of feeding an identical standard basal diet. Plasma extracted at fasting state from five beagles and five greyhounds was analysed by GC. Plasma ALA, EPA and LA increased steadily and significantly from days 0 to 22 (P < 0·05); however, no significant breed differences were shown. Plasma DHA levels, on the other hand, showed no significant increase over time, but a significant breed difference was observed, with beagles having higher plasma level from day 0 (P = 0·002). This breed difference requires further investigation. Levels of ALA and EPA were still rising significantly between days 15 and 22, indicating that PUFA levels in plasma had not stabilised in 3 weeks. These findings together suggest that flaxseed oil could be a useful source of PUFA in dogs, especially ALA and EPA, and that breed differences may be important.

Merino ewes (n 108) joined to a single sire were allocated into three flocks, with ewes in one flock being chemically defaunated in the second month of gestation. Single lambs born to defaunated ewes (BF lambs) were heavier at birth and at weaning than lambs born to faunated ewes (F lambs). After weaning, all BF and F lambs were individually housed then half of the F lambs were chemically defaunated (DF lambs). In trial 1, BF, DF and F lambs were offered a concentrate-based diet containing either 14 or 19 % protein for a 10-week period. Wool growth rate of BF lambs was 10 % higher than that of DF or F lambs and was increased 9 % by the high-protein diet. While there was no main effect of protozoa treatment on enteric methane production, there was an interaction between protozoa treatment and diet for methane production. BF and DF lambs produced more methane than F lambs when fed the low-protein diet but when fed the high-protein diet, emissions were less than (BF lambs) or not different from (DF lambs) emissions from F lambs. In trial 2, lambs were offered 800 g roughage per d and, again, methane production was not affected by the presence of protozoa in the rumen. The data indicate that while lambs without rumen protozoa have greater protein availability than do faunated ruminants, there is no main effect of rumen protozoa on enteric methane production by lambs fed either a concentrate or roughage diet.

Marek's disease virus (MDV) is the causative agent of Marek's disease (MD) in the chicken. MDV is an important oncogenic avian pathogen that leads to world-wide economic costs to the poultry industry estimated at more than $US1 billion. Natural infection is via inhalation of feather dander containing the virus then infects lymphocytes and feather follicle epithelial cells from which virus is shed in dander subsequently. Infection of lymphocytes causes lysis and immunosuppression followed by either latent infection or transformation and induction of neoplastic lymphomas in various organs. MDV is still a major concern for the poultry industry in spite of widespread vaccine use, partly because of isolation of very virulent strains from vaccinated chickens. This thesis investigates aspects of the pathogenesis and molecular epidemiology of MD in chickens relevant to the current MD situations in Iraq and Australia.

Feed efficiency is an economically important trait in beef production. It can be measured as residual feed intake. This is the difference between actual feed intake recorded over a test period and the expected feed intake of an animal based on its size and growth rate. DNA-based marker-assisted selection would help beef breeders to accelerate genetic improvement for feed efficiency by reducing the generation interval and would obviate the high cost of measuring residual feed intake. Although numbers of quantitative trait loci and candidate genes have been identified with the advance of molecular genetics, our understanding of the physiological mechanisms and the nature of genes underlying residual feed intake is limited. The aim of the study was to use global gene expression profiling by microarray to identify genes that are differentially expressed in cattle, using lines genetically selected for low and high residual feed intake, and to uncover candidate genes for residual feed intake. A long-oligo microarray with 24 000 probes was used to profile the liver transcriptome of 44 cattle selected for high or low residual feed intake. One hundred and sixty-one unique genes were identified as being differentially expressed between animals with high and low residual feed intake. These genes were involved in seven gene networks affecting cellular growth and proliferation, cellular assembly and organization, cell signalling, drug metabolism, protein synthesis, lipid metabolism, and carbohydrate metabolism. Analysis of functional data using a transcriptional approach allows a better understanding of the underlying biological processes involved in residual feed intake and also allows the identification of candidate genes for marker-assisted selection.

Long chain 'n'-3 fatty acids are beneficial to mammals because of their anti-inflammatory role. However, whether flaxseed oil, which is rich in short chain 'n'-3 fatty acids, has such a role, it has not been extensively examined. This study investigated the supplementation of flaxseed oil on the regulation of genes involved in inflammatory responses such as heat shock proteins ('HSP90' and 'HSP70') and interleukin ('IL1β') in the white blood cells of dogs. Five beagles and 5 greyhounds were supplemented with Melrose® flaxseed oil at the rate of 100 mL/kg food for 21 days. The blood was collected at day 0, 15, and 22 following supplementation. The expression of 3 genes was quantified using real-time polymerase chain reaction. Plasma concentrations of fatty acids such as alpha linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, and arachidonic acid were measured, and their correlations with changes in gene expression were determined. Flaxseed oil supplementation downregulated the expression of 'HSP90' and 'IL1β' in greyhounds but showed no significant effect on these genes in beagles. 'HSP70' remained unchanged in both breeds following the supplementation. Correlations of 'HSP90' and 'IL1β' expression levels with the plasma fatty acid concentrations on day 22 showed a significant negative correlation in greyhounds. Dietary flaxseed oil altered the expression of genes involved in inflammation in white blood cells. Because the expression of the genes may vary in different breeds, it will be useful to consider breed responses to dietary manipulation in canine nutrition management.