How farming systems simulation can aid the development of more sustainable smallholder farming systems in southern Africa

Over the past 20 years, farming systems modelling has become an accessible tool for developing intervention strategies targeted at smallholder farmers in southern Africa. Applying the Agricultural Productions Systems sIMulator (APSIM) to credibly simulate key soil and crop processes in highly constrained, low yielding maize/legume systems has led to four distinct modes of use: (i) to add value to field experimentation and demonstration; (ii) in direct engagement with farmers; (iii) to explore key system constraints and opportunities with researchers and extension agencies; and (iv) in the generation of information for policy makers, bankers and insurance institutions. Examples of application in each of these modes are presented. Despite being demonstrated as an excellent tool for developing intervention strategies and extension material, the use of simulation is limited by a lack of competent local users. Better co-operation within the simulation community, sharing of climate, soil and crop parameterisation and validation datasets, and focussing of efforts on using models to benefit smallholder farmers are suggested as ways of increasing the use and relevance of simulation. Substantial investment in the training of agriculturalists and the further science development of systems simulation is required to tackle the enormous challenges facing agricultural development in the region.     

Application of electron spin resonance spectroscopy and spin probes to investigate the effect of ingredients on changes in wheat dough during heating

The change in microviscosity of the aqueous and lipid phases of wheat flour dough, during heating and subsequent cooling, has been measured using novel spin probes based on the isoindolin-yloxyl structure. The spin probes, water and/or lipid soluble, were used with combinations of dough ingredients: diacetyl tartaric acid ester of monoglycerides (DATEM), salt, yeast, and sodium ascorbate. The lipid soluble probe showed that DATEM does not produce a homogeneous phase with endogenous lipids but is found in a separate, less mobile phase. Also, the lipids were shown not to be involved in the baking process, although DATEM may be incorporated into the gelled starch matrix. The water soluble probe enabled starch gelatinization to be investigated in detail and showed that gelatinization produces a reduction of dielectric constant. The technique is appropriate for the detailed examination of the behavior of different ingredients during baking and also potentially to examine interactions between ingredients and flour components in dough.     

Relationship of glycaemic index with cardiovascular risk factors: analysis of the National Diet and Nutrition Survey for people aged 65 and older

OBJECTIVE: To identify associations between dietary glycaemic index (GI) and weight, body mass index and other risk factors for cardiovascular disease (CVD) - waist-to-hip ratio (WHR), lipoprotein fractions, triacylglycerols (TAG) and blood pressure (BP) - in an older British population. DESIGN: Cross-sectional dietary, anthropometric and biochemical data from the National Diet and Nutritional Survey for adults aged over 65 years were reanalysed using a hierarchical regression model. Associations between body weight, CVD risk factors, and dietary factors including GI and fibre intakes were explored among 1152 healthy older people living in the UK between 1994 and 1995. RESULTS: In the unadjusted model, GI was significantly and directly associated with TAG (beta = 0.008 +/- 0.003) and diastolic BP (beta = 0.325 +/- 0.164) in males. These relationships were attenuated and non-significant after adjustment for potential confounding factors. WHR (beta = 0.003 +/- 0.001) and TAG (beta = 0.005 +/- 0.002) were significantly predicted by GI in males and females combined. The association with WHR was attenuated by adjustment for sex, age, region and social class; the relationship with TAG was non-significant after adjustment for other potential dietary confounders. CONCLUSION: After controlling for potential confounders, no clear links were detected between GI and body weight or other CVD risk factors. This study provides little evidence for advising the consumption of a low-GI diet in the elderly to prevent weight gain or improve other CVD risk factors.     

Dispersal of breeding, adult male Phocarctos hookeri: Implications for disease transmission, population management and species recovery

Dispersal impacts on a range of population parameters making it a key piece of information in species conservation. Despite its importance, dispersal is poorly characterized for many species: pinnipeds are no exception. Understanding dispersal patterns of the New Zealand sea lion Phocarctos hookeri is crucial in the conservation management of the species as its recovery to a non-threatened status hinges on range recolonisation. In this study, we examined the movements of breeding adult male New Zealand sea lions within and following the breeding season of the 2002/03 austral summer using a novel multi colony approach. Based on resightings of 202 individually identifiable adult males, we found (1) a previously unappreciated, high level of dispersal by adult territorial males between breeding colonies during the pupping period and (2) that breeding males disperse to the extremes of the species’ range at the end of female oestrous. Our findings are contrary to the current paradigm of otariid breeding behaviour, which is believed to consist of prolonged, uninterrupted male territoriality based on intense male-male competition and sustained fasting. Adult male dispersal between colonies and across the species range has important implications for adult males as vectors of disease in three recent epizootics, species management and species recovery via recolonisation as males are apparently remaining part of a localized, vulnerable breeding population.     

Population genetic structure in Lens taxa revealed by isozyme and RAPD analysis

An understanding of the genetic structure of populations is vital for the formation of optimum collection, conservation and utilization strategies for plant genetic resources. This is of particular importance in the case of in-situ conservation, a strategy gaining in popularity. The population genetic structures of five wild lentil taxa, Lens culinaris subsp. orientalis, L. odemensis, L. ervoides, L. nigricans and L. lamottei were investigated using isozyme electrophoresis and random amplified polymorphic DNA (RAPD). Approximately 20 plants from each of 5 populations per taxon were screened for variation at 11 isozyme loci and using three RAPD primers. Levels of variation were generally low, although considerable variation existed in the levels of diversity found within populations of L. culinaris subsp. orientalis and L. lamottei. Comparison of the results obtained in this study with the results obtained in a previous study indicate that this is a trend occurring across all species. It implies that levels of diversity within populations must be measured and considered prior to targeting of specific populations for in-situ conservation. Analysis of molecular variance of both isozyme and RAPD data revealed that between 78% and 99% of the variation was attributable to between-population differences. Isozyme results from L. lamottei populations were, however, contradictory. Possible explanations for this difference are discussed.     

Cardiopulmonary effects of xylazine sedation in the foal

Six healthy foals underwent instrumentation for measurement of the cardiopulmonary effects of sedation with 1.1 mg/kg bodyweight xylazine hydrochloride given intravenously. Responses to xylazine in foals at 10 and 28 days of age were not significantly different. Foals became sedate and markedly ataxic, and four of the six foals became recumbent. Heart rate decreased significantly but no arrhythmias were detected. Arterial blood pressure increased initially and then fell significantly below pre-injection values. Changes in respiratory airflow, upper airway obstruction and respiratory noise were noted in the initial 20 mins of sedation, after which respiratory rate fell, tidal volume increased, and minute volume decreased gradually. Arterial blood gas tensions and pH did not change significantly during the 120 mins following xylazine administration. Control studies showed no significant changes. All foals recovered uneventfully.     

The use of the enzyme-linked immunosorbent assay (ELISA) to detect the IgM and IgG antibody response to Leptospira interrogans serovars hardjo, pomona and tarassovi in cattle

Leptospira interrogans serovars pomona, hardjo and tarassovi were each used to inoculate 6 cattle. Three-hundred and ninety-nine sera collected from the inoculated animals and from a control group over a 3-month period were tested using the microscopic agglutination test (MAT) and the enzyme-linked immunosorbent assay (ELISA). Leptospiruria was monitored by microscopic examination and culture. The ELISA detected specific IgM antibody against the serovars in all infected cattle 1 week after inoculation. This IgM antibody persisted in most of the animals for 3-5 weeks. Specific IgG antibody appeared at the same time or just after IgM, but persisted for much longer. Levels of antibody detected by the ELISA and the MAT did not correlate with each other, nor with the periods of leptospiruria found in the infected cattle.     

Effect of Morphology of Mechanically Developed Wheat Flour and Water on Starch from Gluten Separation Using Cold Ethanol Displacement

The mechanical development of wheat flour and water creates micro and macro structures in dough or batter that critically influence the ability to separate starch from protein by fluid displacement. This study sought to identify specific structural and rheological features and to relate these to separation as indexed by the separation factor. Structural features, especially protein and starch distributions, were examined using visible light microscopy applied to dough samples that had been exposed to a protein dye. Flour and water samples were developed in a Brabender microfarinograph at conditions (water content and time of development) generally suitable for use of the USDA Western Regional Research Center, cold‐ethanol fluid‐displacement method. No truly homogenous structures were observed. However, distinct segregation of protein and starch were apparent at all conditions. Structural features correlated qualitatively with the success of separation indexed by the overall separation factor (α_p/s) for the separation process. Highly segregated states characterized by large protein bands, clustered starch, and large open spaces were obtained with intermediate development (25 ± 5 min) and were most readily separated (α_p/s = 118 ± 7). Segregated states with relatively thin protein bands (≤10 μm dia) in complex networks entrapping starch were obtained after additional development (≥45 min) and were less completely separable (α_p/s = 32 ± 2). Segregated states with irregularly organized protein in the form of clumps and bands were obtained with minimal development and were partially separable (α_p/s = 65 ± 4). Consistency indicated on the microfarinograph increases monotonically throughout and beyond the period of maximum separability. However, elasticity changes and a high rate of increase in consistency evident in the microfarinogram may reflect changes in the structure that also reduce separability. The study demonstrated the use of the ethanol method to isolate development from displacement phenomena forindependent study.