In this issue – July 2009

Musculoskeletal disorders in Queensland veterinarians  ▪  Australian surveillance for avian influenza viruses in wild birds  ▪  Splenic lymphoma in an echidna  ▪  Post-thaw motility of equine semen  ▪  Serum cobalamin concentrations in cats  ▪  Acute toxicity of snail and slug bait in dogs  ▪  Topical hydrocortisone aceponate for flea-allergy dermatitis in dogs  ▪  Activated coagulation times in normal cats and dogs  ▪  Acquired arachnoid cyst in a cat     

SCIENTIFIC AND CLINICAL: In this issue – September 2010

Agricultural shows and communicable disease transmission in poultry · Capsule endoscopy in horse small intestine · Acute lameness from a bone metastasis in a horse · Tidal breathing flow volume loop in dogs with tracheal masses · Intracranial meningioma and facial myokymia in a dog · Caudal epidural flank anaesthesia using multiport catheters in cattle · Needle-free vaccination in sheep · Smoking vets in Australia     

用β-甘露聚糖酶改善单胃动物对大豆的利用

饲用酶对于养禽业和养猪业来说并非新事物 ,但因其能节约饲料成本并能减轻畜牧生产对环境的污染 ,人们对其的兴趣与日俱增。在以小麦为基础的日粮中添加木聚糖酶而在以大麦为基础的日粮中添加 β-葡聚糖酶 ,可改善日粮的消化率并降低肠道内容物的粘稠度。所以 ,在主要应用这些饲料的地方都广泛使用这些酶 ,比如在北欧以及在北美和大洋洲的某些地区。许多日粮中还应用植酸梅以便减少粪中的磷。不过 ,酶制剂在以玉米 -大豆为基础的单胃动物日粮中的应用还非常有限。最近对于能量利用、体重均一度以及与健康状态有关的参数所作的研究表明 ,用 …     

THE EFFECT OF THE ADDITION OF ARACHIS OIL ON THE CONSERVATION OF HEAVILY–WILTED HERBAGE SEALED IN POLYTHENE FILM

A conservation experiment is described in which arachis oil was used to improve the energy content of heavily-wilted herbage of approximately 46% dry matter. The 2 oil-treated herbages and 2 control silages were enclosed in polythene film. The DM losses from all 4 silos were high compared with losses normally encountered in completely sealed silos. This is attributed to secondary fermentation which occurred after the silos were opened. The oil had a depressing effect on the digestibility of the mineral matter of both grass and silage. The metabolizable energy values of the silages are reported and discussed.     

Restricted and Satiate Feeding of Two Genetically Isolated Strains of Juvenile Channel Catfish Ictalurus punctatus Reared on 28% and 32% Protein Diets

A 10-wk growth comparison trial of two strains of channel catfish Ictalurus punctatus was conducted in 40 120-L flow-through aquaria using a 2 ± 2 × 2 factorial experiment design. The three factors evaluated were: strain (Norris and NWAC103), dietary protein level (28% and 32%), and feeding rate (restricted and satiate). Average initial weight (× SD) for the Norris strain was 3.0 ± 0.08 g/fish, while that of the NWAC103 strain was 4.7 ± 0.13 g/fish. The feeding rate for the satiated group was adjusted based on feeding observations. The feeding rate for the restricted group was adjusted to about ²/₃ of the satiate level. For both satiate and restricted feeding regimens, the NWAC103 strain consumed more feed than the Norris strain. Fish of Norris strain fed the 32% protein diet consumed more feed than fish fed the 28% protein diet; however, there were no differences in feed consumption in the NWAC103 fish fed the two protein diets. Regardless of feeding rate, the NWAC103 fish gained more weight and converted feed more efficiently than the Norris fish. Fillet composition was not affected by fish strain. Fish fed the 28% protein diet had a lower level of fillet protein than fish fed the 32% protein diet. In fish fed to satiation, a 32% protein diet resulted in a lower fillet fat level than a 28% protein diet, but no differences were observed in fillet fat levels between fish fed the two dietary protein levels for the restricted group. Results from the present study demonstrate that under laboratory conditions, the NWAC103 strain of channel catfish is superior to Norris strain in feed consumption, growth rate, and feed efficiency. Our data also indicate that either a 28% or 32% protein diet can be fed to either strain of channel catfish whether they are fed to satiation or fed a restricted ration with no detrimental effects on growth.     

A histological evaluation of facial suture lines in six horses aged 1 day to 9 years

Craniofacial sutures are fibrous connections between the flat bones in the skull, allowing a small amount of movement to absorb strain and load as long as they are patent. In the present study, we examined the histological appearance of facial suture lines in horses of different ages. The internasal, nasofrontal and maxillolacrimal sutures were macroscopically identified and extracted from the skulls of six horses aged 1 day (two horses), 5 days, 2, 6 and 9 years and prepared into histological samples. The suture lines were then examined for width, form, cell density and morphology, vascularisation and morphology of the surrounding tissue and compared based on the age of the horse. Although macroscopically the sutures became difficult to identify in the 6- and 9-year-old horses, histologically they were clearly visible in all samples, indicating that the sutures were patent and consisted of connective tissue in all analysed horses. The sutures became subjectively narrower with lower cell density in older horses as compared to young horses, and there was a noticeable maturation from woven to cancellous bone surrounding the sutures. Vascular structures were present in all sutures regardless of age or location. In conclusion, this study raises awareness of the histological suture conformation in neonatal and adult horses and their persistence into adulthood. A better understanding of the histological structure of facial sutures and their continued patency into adulthood can aide in the interpretation of radiographs and computed tomography images of the head and in improving treatment methods and outcomes for horses affected with suture exostosis. In addition, if biopsies are taken, clinicians will have a basis on which to determine which cells are related to the disease process and which are normally occurring.     

Effects of elevated carbon dioxide concentration on growth and nitrogen fixation in Alnus glutinosa in a long-term field experiment

Nitrogen-fixing plant species may respond more positively to elevated atmospheric carbon dioxide concentrations ([CO2]) than other species because of their ability to maintain a high internal nutrient supply. A key factor in the growth response of trees to elevated [CO2] is the availability of nitrogen, although how elevated [CO2] influences the rate of N2-fixation of nodulated trees growing under field conditions is unclear. To elucidate this relationship, we measured total biomass, relative growth rate, net assimilation rate (NAR), leaf area and net photosynthetic rate of N2-fixing Alnus glutinosa (L.) Gaertn. (common alder) trees grown for 3 years in open-top chambers in the presence of either ambient or elevated atmospheric [CO2] and two soil N regimes: full nutrient solution or no fertilizer. Nitrogen fixation by Frankia spp. in the root nodules of unfertilized trees was assessed by the acetylene reduction method. We hypothesized that unfertilized trees would show similar positive growth and physiological responses to elevated [CO2] as the fertilized trees. Growth in elevated [CO2] stimulated (relative) net photosynthesis and (absolute) total biomass accumulation. Relative total biomass increased, and leaf nitrogen remained stable, only during the first year of the experiment. Toward the end of the experiment, signs of photosynthetic acclimation occurred, i.e., down-regulation of the photosynthetic apparatus. Relative growth rate was not significantly affected by elevated [CO2] because although NAR was increased, the effect on relative growth rate was negated by a reduction in leaf area ratio. Neither leaf area nor leaf P concentration was affected by growth in elevated [CO2]. Nodule mass increased on roots of unfertilized trees exposed to elevated [CO2] compared with fertilized trees exposed to ambient [CO2]. There was also a biologically significant, although not statistically significant, stimulation of nitrogenase activity in nodules exposed to elevated [CO2]. Root nodules of trees exposed to elevated [CO2] were smaller and more evenly spaced than root nodules of trees exposed to ambient [CO2]. The lack of an interaction between nutrient and [CO2] effects on growth, biomass and photosynthesis indicates that the unfertilized trees maintained similar CO2-induced growth and photosynthetic enhancements as the fertilized trees. This implies that alder trees growing in natural conditions, which are often limited by soil N availability, should nevertheless benefit from increasing atmospheric [CO2].