Soluble matrix of hen's eggshell extracts changes in vitro the rate of calcium carbonate precipitation and crystal morphology

1. Extra and intramineral eggshell matrix proteins were solubilised before and after demineralisation by sequential extractions using guanidine hydrochloride and EDTA.

2. The intramineral electrophoretic profile of SDS‐PAGE showed the presence of 80, 66, 43, 36 and 15 kDa bands with a predominance of a 17 kDa band. In the extramineral part, the major protein was the 15 kDa band.

3. The introduction of intramineral extract to a metastable solution of calcium carbonate delayed the rate of crystal growth. The delay in the rate of precipitation was elicited by a single fraction (MW 50–80 kDa), isolated by gel filtration chromatography, of eggshell extracts. Extramineral extracts had no effect.

4. Addition in vitro of intramineral eggshell extracts modified the morphology of calcite; the crystals aggregated and showed irregular surfaces.

5. These observations suggest that constituents of the eggshell matrix are involved in the control of calcite growth and crytallographic structure of the hen's eggshell.     

Myocarditis caused by naturally acquired canine distemper virus infection in 4 dogs

Canine distemper virus (CDV) has long been recognized as a cause of myocarditis; however, cases of myocarditis caused by naturally acquired CDV infection have been reported only rarely in dogs. We describe here our retrospective study of naturally acquired systemic CDV infection in 4 dogs, 4–7 wk old, that had myocarditis, with myocardial necrosis and fibrosis. One of the 4 dogs had intracytoplasmic eosinophilic inclusion bodies in cardiomyocytes. Other lesions included bronchointerstitial pneumonia (4 of 4), necrotizing hepatitis (2 of 4), splenic lymphoid necrosis (2 of 4), encephalitis (1 of 3; brain was not submitted in 1 case), and necrotizing gastroenteritis (1 of 4). The presence of CDV in the heart was confirmed by immunohistochemistry in all 4 dogs.     

EXPLORING THE RECYCLING OF MANURE FROM URBAN LIVESTOCK FARMS: A CASE STUDY IN ETHIOPIA

• Livestock manure was the main organic waste in urban and peri-urban areas.• Manure production will increase by a factor of 3–10 between 2015–2050.• Only 13%–38% of excreted N by livestock will be recycled in croplands.• Intensification of urban livestock production greatly increased N surpluses.• Reducing population growth and increasing livestock productivity needed.Urban population growth is driving the expansion of urban and peri-urban agriculture (UPA) in developing countries. UPA is providing nutritious food to residents but the manures produced by UPA livestock farms and other wastes are not properly recycled. This paper explores the effects of four scenarios: (1) a reference scenario (business as usual), (2) increased urbanization, (3) UPA intensification, and (4) improved technology, on food-protein self-sufficiency, manure nitrogen (N) recycling and balances for four different zones in a small city (Jimma) in Ethiopia during the period 2015-2050. An N mass flow model with data from farm surveys, field experiments and literature was used. A field experiment was conducted and N use efficiency and N fertilizer replacement values differed among the five types of composts derived from urban livestock manures and kitchen wastes. The N use efficiency and N fertilizer replacement values were used in the N mass flow model.Livestock manures were the main organic wastes in urban areas, although only 20 to 40% of animal-sourced food consumed was produced in UPA, and only 14 to 19% of protein intake by residents was animal-based. Scenarios indicate that manure production in UPA will increase 3 to 10 times between 2015 and 2050, depending on urbanization and UPA intensification. Only 13 to 38% of manure N will be recycled in croplands. Farm-gate N balances of UPA livestock farms will increase to>1 t·ha⁻¹ in 2050. Doubling livestock productivity and feed protein conversion to animal-sourced food will roughly halve manure N production.Costs of waste recycling were high and indicate the need for government incentives. Results of these senarios are wake-up calls for all stakeholders and indicate alternative pathways.     

Livestock water productivity in mixed crop–livestock farming systems of the Blue Nile basin: Assessing variability and prospects for improvement

Water scarcity is a major factor limiting food production. Improving Livestock Water Productivity (LWP) is one of the approaches to address those problems. LWP is defined as the ratio of livestock’s beneficial outputs and services to water depleted in their production. Increasing LWP can help achieve more production per unit of water depleted. In this study we assess the spatial variability of LWP in three farming systems (rice-based, millet-based and barley-based) of the Gumera watershed in the highlands of the Blue Nile basin, Ethiopia. We collected data on land use, livestock management and climatic variables using focused group discussions, field observation and secondary data. We estimated the water depleted by evapotranspiration (ET) and beneficial animal products and services and then calculated LWP. Our results suggest that LWP is comparable with crop water productivity at watershed scales. Variability of LWP across farming systems of the Gumera watershed was apparent and this can be explained by farmers’ livelihood strategies and prevailing biophysical conditions. In view of the results there are opportunities to improve LWP: improved feed sourcing, enhancing livestock productivity and multiple livestock use strategies can help make animal production more water productive. Attempts to improve agricultural water productivity, at system scale, must recognize differences among systems and optimize resources use by system components.     

Probabilistic risk assessment of agrochemicals in the environment

Concern for the environment has resulted in greater scrutiny of both old and new plant protection products and increased efforts have been directed to developing more rigorous but more realistic procedures for the ecotoxicological risk characterization of these agrochemicals. These techniques include probabilistic analysis of toxicity and exposure data and better understanding of the relationship between structure and function in populations of wildlife and the role of keystone species in maintaining ecosystem functioning. The ecological risk assessment method described here is centered on the use of probabilistic distribution functions that independently describe exposure concentrations and toxicological responses of organisms to the chemical of concern. The distributions are transformed to permit calculation of linear regression parameters. The regression parameters for the two distributions are then used to determine joint probabilities which interrelate the exposure and toxicology data. For ease of presentation the results are presented as an exceedence plot which depicts, based on the exposure data the percent of species likely to be affected and the percent of observations likely to cause this level of effect. In this paper, the use of the method is illustrated using data for chlorpyrifos in North American aquatic environments. These probabilistic risk assessment methods are being assessed for incorporation into assessment procedures in a number of regulatory jurisdictions.     

Public sector soybean (Glycine max) breeding: Advances in cultivar development in the African tropics

Formal public sector soybean breeding in Africa spans over four decades, and it was initiated by the International Institute of Tropical Agricultural (IITA). As the demand of soybean continues to outstrip production, strategic projects such the Tropical Legume (TL) were initiated, in which the main goal was to enhance the productivity of soybean in the farmers’ fields in Sub‐Saharan Africa. One of the strategies to enhance the productivity of soybean in the farmers’ fields is through developing and deploying improved soybean varieties in the target countries. Through the TL I and TL II projects, a number of varieties were released in the target countries, Kenya, Nigeria, Malawi and Mozambique by employing participatory variety selection (PVS). This review provides highlights of the achievements made by IITA breeding programme and insights of what needs to be done to enhance yield improvement for soybean in Africa using demand‐driven breeding approaches.     

Genetic divergence in two tropical maize composites after four cycles of reciprocal recurrent selection

Two tropical maize composites were subjected to four cycles of reciprocal recurrent selection to develop divergent inbred lines with good combining ability. This study was conducted to examine the extent of genetic diversity, changes in allele composition and genetic structure, of 100 randomly selected S₁ lines each from the original (C₀) and advanced (C₄) selection cycles of TZL COMP3 and TZL COMP4, genotyped using single nucleotide polymorphism (SNP) markers. Results revealed that the proportion of alleles at both low and high frequencies decreased from C₀ to C₄, whereas those at intermediate frequencies increased at C₄ in the two composites. More unique and other alleles were lost at C₄ in TZL COMP3 relative to those in TZL COMP4. The changes in different measures of genetic diversity were either small or negligible with selection in the two composites. The proportion of markers departing from Hardy–Weinberg equilibrium (HWE) decreased with selection, whereas the total number of pairs of markers in linkage disequilibrium increased with selection in the two composites. Examination of changes in population structures using a model‐based approach as well as cluster and multivariate analyses found a high degree of concordance in stratifying the 400 S₁ lines into four non‐overlapping groups corresponding to the two selection cycles each within the reciprocal composites. The observed molecular‐based divergence between cycles within the same composite and the clear differentiation between the complementary composites highlight the importance of reciprocal recurrent selection for preserving genetic diversity for long‐term selection. This increases the potential of the advanced selection cycles to sustain genetic gain in productivity of hybrids adapted to the savannas in West and Central Africa.     

Efficiency of SNP and SSR-based analysis of genetic diversity,population structure,and relationships among cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) germplasm from East Africa and IITA inbred lines

The extent of genetic diversity and relatedness of cowpea germplasm from East Africa are poorly understood. A set of 13 microsatellites (SSR) and 151 single nucleotide polymorphisms (SNPs) markers were applied to assess the levels of genetic diversity in a sample of 95 accessions of local cowpea germplasm and inbred lines of Vigna unguiculata. The average genetic diversity (D), as quantified by the expected heterozygosity, was higher for SSR loci (0.52) than for SNPs (0.34). The polymorphic information content was 0.48 for SSR and 0.28 for SNP while the fixation index was 0.095 for SSR and 0.15 for SNPs showing moderate differentiation and high gene flow among cowpea accessions from East African countries. The results of data analysis of both SSR and SNP markers showed similar clustering patterns suggesting a substantial degree of association between origin and genotype. Principal coordinate analysis (PCoA) with SSR and SNP markers showed that accessions were grouped into two and three broad groups across the first two axes, respectively. Our study found that SNP markers were more effective than SSR in determining the genetic relationship among East African local cowpea accessions and IITA inbred lines. Based on this analysis, five local cowpea accessions Tvu-13490, Tvu-6378, Tvu-13448, Tvu-16073, and 2305675 were identified to be tightly clustered sharing several common alleles with the drought tolerant variety Danila when analyzed with SSR and SNP markers. The findings will assist and contribute to future genetic diversity studies aimed at the genetic improvement of local Eastern Africa cowpea accessions for improved overall agronomic performance in general and breeding for drought tolerant in particular.     

Exploitation of predators in UK fruit and hop culture

A wide range of species of predators has been exploited, or has the potential to be exploited, as biological control agents against pests of fruit and hop. They include members of the families Miridae, Anthocoridae and Chrysopidae, and of the mite family Phytoseiidae. Some species can colonise fruit plantations naturally, whereas others are mass-cultured and introduced artificially. The characteristics of the various predator species are considered in relation to the requirements for biological control agents in specific crop situations.     

Transmission electron microscopy of the vertical crystal layer and cuticle of the eggshell of the domestic fowl

1. Eggshell pieces (1 cm2) were decalcified using a solution of EDTA (200 g/litre, pH 6.9 to 7.0) in paraformaldehyde (2 g/litre) and glutaraldehyde (0.5 g/litre) in phosphate buffer. 2. They were prepared for transmission electron microscopy (TEM). 3. TEM identified a vertically aligned matrix associated with the vertical crystal layer (VCL). It is hypothesised that the vertical orientation of calcite crystals in the VCL is closely linked to this vertical matrix. 4. TEM also revealed the presence of a 2-layered cuticle, the inner layer containing vesicles which were absent in the outer. 5. Cuticular vesicles contain hydroxyapatite and are thought to play a role in the termination of shell formation. The current paper presents data relating to microbial apatitic systems that strengthen this hypothesis.