Sirius: a mechanistic model of wheat response to environmental variation

Sirius is a wheat simulation model that calculates biomass production from intercepted photosynthetically active radiation (PAR) and grain growth from simple partitioning rules. Leaf area index (LAI) is developed from a thermal time sub-model. Phenological development is calculated from the mainstem leaf appearance rate and final leaf number, with the latter determined by responses to daylength and vernalisation. Effects of water and N deficits are calculated through their influences on LAI development and radiation-use efficiency. This paper describes the model and its validation using data from independent and near independent experiments at Lincoln, New Zealand, and Rothamsted, UK. Despite there being no calculation of tiller dynamics or grain number, the model accurately simulated the behaviour of crops exposed to a wide range of conditions. We conclude that the accurate prediction of phenological development and LAI is much more important for grain yield prediction than are the components of yield. Although grain population is not a necessary step in yield calculation in Sirius, the model proved useful in investigating the effects of stress in setting grain number. The analysis showed that the influence of stress on partitioning of biomass to the ear during pre-anthesis ear growth was much more important in determining grain number than was the effect on biomass accumulation during the same phase.     

Effects of alternate phases of fish oil and vegetable oil-based diets in Murray cod

Fish oil (FO)- and canola oil (CO)-based diets were regularly alternated in a daily cycle (amCO: alternation of CO in the morning and FO in the afternoon, and pmCO: alternation of FO in the morning and CO in the afternoon) or in a series of weekly cycles (2W: alternation of 2 weeks on CO and 2 weeks on FO, 4W: alternation of 4 weeks on CO and 4 weeks on FO), over a 16-week period in juvenile Murray cod ( Maccullochella peelii peelii ). No significant differences were observed between any of the treatments in relation to the final weight. However, fish subjected to the 2W schedule were larger ( P >0.05) than all other treatments (37.2 ± 0.30 vs. 34.3 ± 0.58 in the control treatment). Fish receiving the 2W treatment had a significantly lower total net disappearance of eicosapentaenoic acid 20:5n-3 (EPA) and docosahexaenoic acid 22:6n-3 (62.1% and 24.0% respectively) compared with the control treatment (fish continuously fed a blend of 50% FO and 50% CO). Likewise, Murray cod receiving the amCO daily schedule had a significantly lower total net disappearance of EPA in comparison with the CD and pmCO treatments. These data point towards the existence of cyclical mechanisms relative to fatty acid utilization/retention.     

Comparison of seroagglutination, ELISA, and indirect fluorescent antibody staining for the detection of K99, K88, and 987P pilus antigens of Escherichia coli.

Seroagglutination (SAT), enzyme-linked immunosorbent assay (ELISA), and indirect fluorescent antibody staining tests (IFAT) were compared for reliability in the detection of pilus antigens K99, K88, and 987P of Escherichia coli. Test sensitivities were compared using mixtures of piliated bacteria of several strains diluted to a constant optical density with a nonpiliated strain. Relative sensitivities and specificities of the 3 tests were also compared using 55 E. coli strains that had previously been serotyped and characterized for pilus genes by DNA probe. Although specificity was not a serious problem with any of the tests, the SAT was relatively nonsensitive. The IFAT showed the greatest sensitivity of the 3 tests in detecting K88, K99, and 987P E. coli.     

Temporal distribution of porcine circovirus 2 genogroups recovered from postweaning multisystemic wasting syndrome affected and nonaffected farms in Ireland and Northern Ireland.

Porcine circovirus type 2 (PCV2) is now recognized as the essential infectious component of porcine postweaning multisystemic wasting syndrome (PMWS). PMWS was first recognized in high-status, specific pathogen-free pigs in Canada in 1991 and is now an economically important disease that affects the swine industry around the world. Recently, reports of genomic studies on PCV2 viruses indicated that 2 distinctive genogroups of PCV2 exist.4,10 This report involves the results of a study on the distribution of predominant PCV2 genogroups recovered from samples taken from PMWS-affected and PMWS-nonaffected farms on the island of Ireland over a 9-year period and the results of a study on PCV2 genogroup recovery from fecal samples taken from a farm in Northern Ireland from 2003 to 2005 that was first diagnosed as PMWS positive in August 2005. The results indicate that, although at least 2 distinct genogroups of PCV2 have been circulating on pig farms on the island of Ireland, there does not appear to be a direct relationship between infection with these different genogroups of PCV2 and the development of PMWS.     

Amoxycillin: clinical trials in dogs and cats

Amoxycillin, a new broad spectrum semi-synthetic penicillin was subjected to preliminary clinical testing in 351 cases in dogs and 264 in cats in veterinary practices. Two formulations were used: capsules by mouth and an aqueous suspension by injection. Those taking part were asked to use amoxycillin in the treatment of all conditions that they considered required an antibiotic and to report their results in terms of success or failure according to criteria laid down. Samples were taken whenever practicable for bacteriology. Dose ranges were 4 to 11 mg per kg for the oral capsules twice daily in dogs and most cats and 11 mg per kg once daily in some cat cases over five days and 2 to 7 mg per kg for the injectable suspension once daily in both species for three to five days. Results for the full range of conditions are given in tabulated form. Overall percentage of success according to the criteria laid down was 80.1%.