Does post‐anthesis heat stress affect plant phenology,physiology, grain yield and protein content of durum wheat in a semi‐arid Mediterranean environment?

Increasing air temperature due to changing climate is projected to decrease the length of the growing season, hasten vegetative development and maturation, and ultimately affect yield of many C3 crops. Previous multilocation trials highlighted strong relationships between thermal trends in the interval “beginning of flowering‐end of grain filling” and grain yield, and protein content in durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.). With the aim to confirm these relationships, nine durum wheat genotypes, including old (Capeiti 8, Senatore Cappelli and Trinakria) and modern (Amedeo, Arcangelo, Mongibello, Simeto, and Svevo) varieties and a Sicilian landrace (Russello) were grown at three different sites representing a climate gradient in Sicily, Italy. Moreover, the effect of post‐anthesis heat stress on these durum wheats was further investigated in two contrasting environments: open‐field (control—C) and greenhouse heat stress (HS). HS shortened the interval “beginning‐end of flowering” of 1.5 days across genotypes, and the “end of flowering‐beginning of grain filling” and maturation of 4.9 days, with a range of 1 day in Arcangelo to 11 days in Cappelli. Advances in main phenophases significantly decreased kernel weight (KW) and grain yield (GY), whereas grain protein content (PC) increased. As expected, a negative relationship was observed between GY and PC, while positive relationships were found for GY and grain‐filling duration (GFD), and GY and KW. Genotypes responded differently to heat stress, as evidenced by the net photosynthesis, transpiration rate, instantaneous water use efficiency and dry matter accumulation in kernels. Genotypes were ranked according to the heat susceptibility index (HSI): Amedeo, Arcangelo, Capeiti 8, Svevo and Trinakria resulted heat‐tolerant. These varieties were characterized by an early trigger of dry matter accumulation in kernels under HS (Amedeo, Arcangelo and Trinakria), or showed similar length of the GFD (Capeiti 8) between environments. The multilocation trial confirmed a negative relationship between maximum temperatures and grain yield, and a positive relationship between minimum temperatures and protein content during grain–filling periods. Research focusing on agronomic strategies, phenology and breeding for tolerance to heat stress is of strategic importance to cope with the detrimental effect of global warming in semi‐arid climates.     

Pharmacokinetics of cephalexin in dogs and cats after oral, subcutaneous and intramuscular administration

A three-way crossover study was carried out in 10 dogs and nine cats to establish the pharmacokinetic parameters of the semi-synthetic cephalosporin antibiotic, cephalexin sodium, when administered orally, subcutaneously or intramuscularly. Ten dogs received a subcutaneous or intramuscular injection of 10 mg/kg bodyweight cephalexin or an oral dose of three 50 mg cephalexin tablets; the peak serum concentrations achieved were 24.9, 31.9 and 18.6 micrograms/ml, respectively, and the times taken to reach these peak levels were 1.2, 0.9 and 1.8 hours. Nine cats received either a subcutaneous or intramuscular dose of 0.25 ml cephalexin suspension (approximately 20 mg/kg bodyweight) or an oral dose of one 50 mg tablet; the peak serum concentrations achieved were 54.0, 61.8 and 18.7 micrograms/ml for the subcutaneous, intramuscular and oral administrations respectively, with times to peak concentrations of 1.1, 0.7 and 2.6 hours.     

Phosphorus Budget in Integrated Multitrophic Aquaculture Systems with Nile Tilapia,Oreochromis niloticus,and Amazon River Prawn,Macrobrachium amazonicum

Integrated multitrophic aquaculture (IMTA) systems are designed mainly for efficient use of resources. Substrates added to aquaculture ponds provide space for periphyton to settle and recover nutrients, making these nutrients available to the species being reared. The present study is centered on the phosphorus budget, analyzing the main ecological compartments of IMTA systems in earthen ponds stocked with Amazon River prawn, Macrobrachium amazonicum, and Nile tilapia, Oreochromis niloticus, with or without different added substrates. The experimental design was completely randomized, with three treatments (without a substrate, with a geotextile fabric substrate, and with a bamboo substrate) and four replications. Phosphorus entered the systems mainly in tilapia feed (ca. 50–61%), inlet water (ca. 17–27%), and fertilizer (ca. 6–7%). Input of phosphorus from other compartments ranged from 1.5 to 1.9%. Most phosphorus was accumulated at the pond bottom as sediment (ca. 60–68%) and fish biomass (ca. 18–26%), or discharged in the outlet water (ca. 7–10%). Feeding is the main driver for the distribution of phosphorus in the ponds. Levels of phosphorus retained in reared animals (20–28%) were higher in these IMTA systems than in tilapia and prawn monocultures (reported as 10–20% and 10–13%, respectively). Nonetheless, the present data showed that the addition of different types of substrates might not improve the recovery of phosphorus in animal biomass as initially supposed. Even so, these IMTA systems decreased the amount of phosphorus released in effluents, and this decrease was enhanced by the addition of substrates, reducing the impact on the receiving waterbodies.     

External quality assurance system for antibiotic resistance in bacteria of animal origin in Europe (ARBAO-II), 2003

Initiated in 2003 by the European Union, ARBAO-II aims to establish a monitoring of antimicrobial susceptibility among the veterinary laboratories in all European countries based on validated methodologies. This includes an external quality control system for the most important bacterial pathogens. In 2003 two trials were performed. The first on Salmonella and Escherichia coli involved 31 laboratories in 18 countries and the second on Staphylococcus and Streptococcus included 22 laboratories in 15 countries. For the E. coli strains, 92.8% of the results complied with the reference MICs, for Salmonella 93.7%, for Streptococcus 80.4% and for Staphylococcus 93.1%. Most problems were observed when testing florfenicol (79.2% correct), gentamicin (84.2%) and amoxicillin + cl (84.9%) in E. coli; streptomycin in Salmonella (62.5%); gentamicin (56.7%), lincomycin (71.4%), clindamycin (75.4%), TMP + sulfonamides (75.7%) and chloramphenicol (78.5%) in Streptococcus; erythromycin (81.5%) and oxacillin (78.2.5%) in Staphylococcus. A few laboratories caused most deviations. However, there was no correlation between good performance for one bacterial group and good performance for other groups. This study showed that most laboratories are capable of performing correct susceptibility testing for E. coli and Salmonella, even though performance of some laboratories can be improved, and that some problems exist for Staphylococcus and Streptococcus. This clearly shows the need for continuous harmonisation of methodologies within the EU.     

Bayesian hierarchical modelling to enhance the epidemiological value of abattoir surveys for bovine fasciolosis

Four classes of Bayesian hierarchical models were evaluated using an historical dataset from an abattoir survey for fasciolosis conducted in Victoria, Australia. The purpose of this analysis was to identify areas of high prevalence and to explain these in terms of environmental covariates. The simplest of the Bayesian models, with a single random effect, validated the use of smoothed maps for cartographic display when the sample sizes vary. The model was then extended to partition the random effect into spatially structured and unstructured components, thus allowing for spatial autocorrelation. Rainfall, irrigation, temperature-adjusted rainfall and a remotely sensed surrogate for rainfall, the normalised difference vegetation index (NDVI), were then introduced into the models as explanatory variables. The variable that best explained the observed distribution was irrigation. Associations between prevalence and both rainfall and NDVI that were significant in fixed effects models were shown to be due to spatial confounding. Nevertheless, provided they are used cautiously, confounded variables may be valid predictors for the prevalence of disease.