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Organic livestock production is a means of food production with a large number of rules directed towards a high status of animal welfare, care for the environment, restricted use of medical drugs and the production of a healthy product without residues (pesticides or medical drugs). The intentions of organic livestock production have been formulated by the International Federation of Organic Agriculture Movements (IFOAM) and were further implemented by EU regulation 2092/91 in the year 2000. The consequences of these rules for the health of the animals were not yet fully anticipated at the time these regulations were made and it has become clear that in some cases the rules are not clear enough thereby even hampering the development of the production system. In this review we shall discuss the implications of these rules for animal health, whereby we shall focus on pig, poultry and dairy production systems. Disease prevention in organic farming is based on the principles that an animal that is allowed to exhibit natural behaviour, is not subjected to stress, and is fed optimal (organic) feed, will have a higher ability to cope with infections than animals reared in a conventional way. Fewer medical treatments would thus be necessary and if an animal would become diseased, alternative treatments instead of conventional drugs should be preferred. Although homeopathy or phytotherapy are recommended according to prevailing regulations, not many organic farmers use this treatment regimen in view of lacking scientific evidence of effectiveness. Important health problems in organic livestock farming are often related to the animals’ outdoor access area. Due to such an area the animals are exposed to various viral, bacterial and parasitic infections some of which may influence the animals’ own welfare but other ones may also endanger the health of conventional livestock (e.g. Avian Influenza) or pose a food safety (Campylobacter, Toxoplasma) problem to the consumer. Many pr

The effects of including forage from semi-natural grassland in the diet of dairy cows were studied in a feeding trial with cows in mid-lactation. Diets were compared in which part of the silage from intensively managed grassland was replaced with 0% (100IM), 20% (20SPP), 40% (40SPP) or 60% (60SPP) silage from species-poor semi-natural grassland or with 60% silage from species-rich semi-natural grassland (60SPR). On a dry matter basis, the total mixed ration (TMR) contained 63% grass silage, 18% maize silage and 19% concentrates. Concentrates were either low or high in protein to prevent protein surpluses or shortages. High producing cows were offered additional concentrates in concentrate boxes. The additional concentrates had the same composition as the concentrates in the TMR. With the 60SPP diet voluntary daily intake decreased by 1.4 kg DM cow¿¹ day¿¹. Uncorrected milk production was the same for all diets, but milk fat yield was lower with the 60SPP diet and milk protein yield lower with the 60SPR diet than with the other diets. No statistically significant differences in fat and protein corrected milk production were observed between the 100IM and the 20SPP diet. The fat and protein corrected milk production with the other diets was significantly lower than with 100IM. All cows gained body weight, but there were no statistically significant differences between diets. In conclusion, if used in low quantities (<40%), silage from semi-natural grassland can be included in the diet of lactating dairy cows without reducing production. This conclusion is based on the presented results and cannot be generalized., In dit onderzoek werden de effecten bestudeerd van foeragering op semi-natuurlijke graslanden in het dieet van melkkoeien

The variation in individual seed electrical conductivity (EC) (µS cm¿¹ g¿¹) of 24 seed lots of two common bean cultivars produced at two locations was quantified using the parameters mean ¿ median, standard deviation (SD), and the range 0¿75%. Also coefficient of variation (CV) was tested, which was regarded not to be a good indicator of this type of variation. Bulk seed lot quality of this material with a very high germination percentage was determined using EC and percentage viable seeds. At physiological maturity (PM), a low variation in individual seed EC as quantified by mean ¿ median, SD and the range 0¿75% was associated with good quality as measured by a low bulk EC and a high percentage of viable seeds. At harvest maturity, associations were less clear than at PM, partly because individual seed variation was smaller and also because bulk EC values differed only slightly among most seed lots. The relationships between individual seed variation and bulk quality were different for the two sites, as shown by a statistically significant improvement of the adjusted R² of the regression when site was included in the regression model, but the relationships were not affected by cultivar. No relationship was found between CV for individual seed EC and bulk quality., Verslag van onderzoek bij bonen naar de relatie tussen variatie in de kwaliteit van individuele zaden, met als maat de elektrische geleidbaarheid en viability, en de kwaliteit van de gehele partij zaden bij oogst rijpheid

A new, flexible curve-fit model for linear to concave rank abundance curves was conceptualized and validated using observational data. The model links the geometric-series model and log-series model and can also fit deeply concave rank abundance curves. The model is based - in an unconventional way - on the negative-binomial distribution and calculates (like the log-series model) a species-diversity index. The index is defined as the expected number of singleton species (species present with one individual) in an infinitely large sample. The new model could satisfy the need for more flexible curve-fit models with which differences and changes in the shape of the rank abundance curve can be more accurately investigated. The common rank abundance curve-fit models are lacking that flexibility

The impact of clustering on rank abundance, species-individual (S-N) and species-area curves were investigated using a computer programme for in silico sampling

Calculating a single-sample rank abundence curve by using the negative-binomial distribution provides a way to investigate the variability within rank abundance replicate samples and yields a measure of the degree of heterogeneity of the sampled community. The calculation of the single-sample rank abundance curve is used in combination with the negative-binomial rank abundance curve-fit model to analyse the principal effect of clustering on the species-individual (S-N) curve and the species-area curve

Verslag van onderzoek bij bonen naar de relatie tussen variatie in de kwaliteit van individuele zaden, met als maat de elektrische geleidbaarheid en viability, en de kwaliteit van de gehele partij zaden bij oogst rijpheid, The variation in individual seed electrical conductivity (EC) (µS cm−¹ g−¹) of 24 seed lots of two common bean cultivars produced at two locations was quantified using the parameters mean − median, standard deviation (SD), and the range 0−75%. Also coefficient of variation (CV) was tested, which was regarded not to be a good indicator of this type of variation. Bulk seed lot quality of this material with a very high germination percentage was determined using EC and percentage viable seeds. At physiological maturity (PM), a low variation in individual seed EC as quantified by mean − median, SD and the range 0−75% was associated with good quality as measured by a low bulk EC and a high percentage of viable seeds. At harvest maturity, associations were less clear than at PM, partly because individual seed variation was smaller and also because bulk EC values differed only slightly among most seed lots. The relationships between individual seed variation and bulk quality were different for the two sites, as shown by a statistically significant improvement of the adjusted R² of the regression when site was included in the regression model, but the relationships were not affected by cultivar. No relationship was found between CV for individual seed EC and bulk quality

Organic agriculture is enhancing specific plant breeding activities to meet its requirements for varieties better adapted to the specific organic environment. To guide this proces the concept of naturalness is very important, which includes three complementary approaches: the non-chemical approach, the agro-ecological approach and the integrity approach. Each of the three approaches has major consequences. This paper analyses cognitive, emotional and normative elements of the three approaches.

Chromosomal location of resistance to Mycosphaerella graminicola was studied in substitution lines of resistant Triticum genotypes into the (susceptible) cultivar Chinese Spring (T. aestivum). (Moderately) resistant genotypes for which substitution lines were available were tested in a first screening. We selected a synthetic hexaploid wheat (Synthetic 6x; T. dicoccoides x T. tauschii), T. spelta and the wheat (T. aestivum) cultivars Cheyenne and Cappelle-Desprez. In a second screening the most suitable Argentinian isolates were identified. We decided to use the isolate IPO 92067 (all sets of substitution lines), IPO 93014 (substitution lines of Synthetic 6x, Cappelle-Desprez and T. spelta) and IPO 92064 (substitution lines of Cheyenne). In the final experiments, substitution lines of the selected genotypes into Chinese Spring were grown in two different environments and inoculated with the selected isolates at the seedling stage (lines of all four selected genotypes) or the adult stage (lines of Synthetic 6x and Cheyenne). Resistance was expressed as (reduction in) necrosis percentage or pycnidial coverage percentage; the two measures were highly (linearly) correlated. When tested in the seedling stage, all chromosomes seemed to carry genes effective against M. graminicola. Many genes were effective against only one isolate or in only one environment or their effects only showed in one resistance parameter. Often these effects were minor. Only chromosome 7D of Synthetic 6x was found with a major effect against both isolates tested. When tested in the adult stage, all lines but the one carrying chromosome 4B from the resistant parent seemed to show genes effective against M. graminicola. The line carrying chromosome 7D from Synthetic 6x showed a level of resistance similar to the resistant parent for isolate IPO 92067, but not for isolate IPO 93014. Major genes, effective against both isolates, were also found on chromosomes 5A and 5D from Synthetic 6x. Lines carryi

A new, flexible curve-fit model for linear to concave rank abundance curves was conceptualized and validated using observational data. The model links the geometric-series model and log-series model and can also fit deeply concave rank abundance curves. The model is based ¿ in an unconventional way ¿ on the negative- binomial distribution and calculates (like the log-series model) a species-diversity index. The index is defined as the expected number of singleton species (species present with one individual) in an infinitely large sample. The new model could satisfy the need for more flexible curve-fit models with which differences and changes in the shape of the rank abundance curve can be more accurately investigated. The common rank abundance curve-fit models are lacking that flexibility.

Calculating a single-sample rank abundance curve by using the negative-binomial distribution provides a way to investigate the variability within rank abundance replicate samples and yields a measure of the degree of heterogeneity of the sampled community. The calculation of the single-sample rank abundance curve is used in combination with the negative-binomial rank abundance curve-fit model to analyse the principal effect of clustering on the species-individual (S-N) curve and the species-area curve. With the usual plotting of S against log N or log area, assuming that N is proportional to area, S-N curves and species-area curves are the same curves with only a shifted horizontal axis. Clustering results in a lower recorded number of species in a sample and stretches the S-N curve and species-area curve over the horizontal axis to the right. In contrast to what is suggested in the literature, we surmise that the effect of clustering on both curves will gradually fade away with increasing sample size. Since the slopes of the curves are not constant, they cannot be used as species diversity indices or site discriminant. S-N curves and species-area curves cannot be extrapolated.

The morphology and rumen fermentation kinetics of the maize cultivars (Zea mays L.) Vitaro and Volens were investigated in detail throughout their growing period as a first step towards understanding the relation between plant characteristics and cell wall fermentability of forage maize. Vitaro is known to have a 9% higher whole plant organic matter digestibility than Volens. Leaf and internode development, fresh (FW) and dry weight (DW) per plant and dry matter content (DMC) of leaves, internodes and developing ears, as well as rumen fermentation characteristics of the stem, were monitored during two seasons. Vitaro plants had a larger final leaf area than Volens plants but their number of leaves (and internodes) was the same. Fully developed Vitaro internodes were shorter and thicker than Volens internodes, resulting in a shorter plant for Vitaro. After anthesis, FW and DW of individual internodes did not vary significantly throughout the growing period. Whole plant FW increased sharply after anthesis, which was associated with the development of the main ear. In both cultivars, DMC of the whole plant more or less doubled between anthesis and harvesting. Vitaro had a higher DW per plant than Volens, but not a larger ear proportion. In rumen fermentation tests on whole stem samples, using the gas production technique, gas production after 72 hours and Tilley & Terry digestibility were significantly higher for Vitaro than for Volens, indicating a higher total degradability for Vitaro. It was concluded that the two cultivars form a suitable model system for studying the causes of differences in rumen fermentation between maize roughages.

The morphology and rumen fermentation kinetics of the maize cultivars (Zea mays L.) Vitaro and Volens were investigated in detail throughout their growing period as a first step towards understanding the relation between plant characteristics and cell wall fermentability of forage maize. Vitaro is known to have a 9% higher whole plant organic matter digestibility than Volens. Leaf and internode development, fresh (FW) and dry weight (DW) per plant and dry matter content (DMC) of leaves, internodes and developing ears, as well as rumen fermentation characteristics of the stem, were monitored during two seasons. Vitaro plants had a larger final leaf area than Volens plants but their number of leaves (and internodes) was the same. Fully developed Vitaro internodes were shorter and thicker than Volens internodes, resulting in a shorter plant for Vitaro. After anthesis, FW and DW of individual internodes did not vary significantly throughout the growing period. Whole plant FW increased sharply after anthesis, which was associated with the development of the main ear. In both cultivars, DMC of the whole plant more or less doubled between anthesis and harvesting. Vitaro had a higher DW per plant than Volens, but not a larger ear proportion. In rumen fermentation tests on whole stem samples, using the gas production technique, gas production after 72 hours and Tilley & Terry digestibility were significantly higher for Vitaro than for Volens, indicating a higher total degradability for Vitaro. It was concluded that the two cultivars form a suitable model system for studying the causes of differences in rumen fermentation between maize roughages.

Internode 7 of the stem of two forage maize (Zea mays L.) cultivars was studied anatomically and chemically at anthesis and subjected to fermentation tests in rumen fluid, using an automated gas production system. For anatomical studies internode 7 was sectioned at the top, middle and base. For chemical analyses and fermentation studies, the internode was divided into five sections. The number of sclerenchyma layers increased from top to base of the internode, whereas cell wall thickness of the sclerenchyma decreased from top to base. The highest and lowest sections of the internode had a higher sugar content and lower levels of neutral detergent fibre, acid detergent fibre, and acid detergent lignin, and slightly higher levels of crude protein than the middle three sections. Also their hemicellulose and cellulose contents were different but the differences with the middle three sections were small. Maximum gas production from fermentation in rumen fluid was higher for cell wall material from the highest and lowest than from the middle three sections. This was mainly due to differences in chemical composition: the highest and lowest section had a higher lignin and a relatively high hemicellulose content compared with the middle three sections. Digestibility of the cultivar with the higher whole plant digestibility, Vitaro, exceeded that of the cultivar Volens for each of the sections examined within the selected internode. Secondary cell wall disappearance was only weakly correlated with lignin content or gas production. This suggests that other factors are important in the fermentation process. These may include anatomical factors influencing the accessibility of the tissues to micro-organisms and chemical and/or physical factors such as lignin composition, lignin localization within the cell wall and nature and extent of cross-linking lignin to other cell wall components.

Organic agriculture is enhancing specific plant breeding activities to meet its requirements for varieties better adapted to the specific organic environment. In the past five years, therefore, attempts have been made to translate the principles of organic farming into rules, regulations and guidelines for organic plant breeding and propagation. These principles are based on the concept of naturalness, which includes three complementary approaches: the non-chemical approach, the agro-ecological approach and the integrity approach. Departing from the concept of naturalness, criteria have been developed to evaluate existing plant breeding and propagation techniques for their compliance to the principles of organic agriculture. Each of the three approaches of the concept of naturalness has major consequences. If these consequences are taken seriously, plant breeding and propagation strategies and techniques for organic farming will greatly differ from breeding and propagation for conventional farming. To better understand the choices to be made and to make them acceptable to the mainstream seed industry, it is necessary to further clarify the underlying framework. This paper provides this clarification by analysing the cognitive, emotive, and normative dimensions of the three approaches. Distinguishing the three different approaches of naturalness in organic agriculture, as well as their three dimensions, and analysing the consequences for the breeding and propagation strategies and techniques can also help to identify and prioritize short-term and long-term steps for the practical development of organic seed production and plant breeding.

Sweet potato (Ipomoea batatas (L.) Lamk) is an important staple food for the people of north-eastern Uganda. Crop yields per unit area are low partly because of biological constraints, including pests like millipedes. The objective of this study was to generate information on pest incidence and control strategies of millipedes by interviewing farmers in different districts. The respondents associated the dying of planting material with drought. However, millipedes also damaged planting material planted early in the rainy season. The sweet potato butterfly (Acraea acerata, Lepidoptera: Nymphalidae) was present, but considered by farmers to be insignificant. Measures to control sweet potato pests, like sanitation, were hardly implemented and insecticides were not used at all. Most respondents performed piecemeal harvesting. Whenever farmers delayed the harvest, they risked severe damage of their sweet potato crops by weevils (Cylas spp., Coleoptera: Curculionidae) and millipedes (Diplopoda). Millipedes pierce and tunnel the storage roots, especially when harvesting is delayed. The farmers did not mention specific natural control agents for millipedes. Knowledge about pests was generally limited, so control strategies were poorly developed, understood and applied.

This paper reports on the results of a diagnostic study conducted to assess the problems and needs of sorghum farmers in north-east Ghana with the aim of determining the type of research that would be useful for them in their own context. The importance of the crop and its position within the cropping system are identified. Sorghum is still an integral part of the livelihoods of farmers. The crop is very versatile and not only contributes to food security but also plays a part in the socio-cultural, socioeconomic, and religious aspects of the lives of farmers. Farmers have different uses for the varieties they grow, which depends on the morphological, agronomic and gastronomic traits of the crop. Sorghum varieties introduced from the research institutions have several problems including lodging, poor grain quality, bird damage and precocious germination. Farmers have developed management strategies for dealing with some of these problems. Nevertheless, further work is required by breeders to make the varieties more acceptable to users. Sorghum production constraints identified include poor soils, erratic rainfall and pest infestation of the grain during storage. The diagnostic study suggests that because farmers produce their own seed, enhancing their ability to improve the quality of their seed would be of benefit to them. The study further underscores the importance and value of diversity for farmers. It also highlights their understanding of diversity, and management and use of variation in their agronomic practices. Areas identified for further research together with farmers aim at enhancing farmers’ knowledge towards strengthening their practices in diversity management and improving seed storage practices.

Sweet potato (Ipomoea batatas (L.) Lamk) is an important staple food for the people of north-eastern Uganda. Crop yields per unit area are low partly because of biological constraints, including pests like millipedes. The objective of this study was to generate information on pest incidence and control strategies of millipedes by interviewing farmers in different districts. The respondents associated the dying of planting material with drought. However, millipedes also damaged planting material planted early in the rainy season. The sweet potato butterfly (Acraea acerata, Lepidoptera: Nymphalidae) was present, but considered by farmers to be insignificant. Measures to control sweet potato pests, like sanitation, were hardly implemented and insecticides were not used at all. Most respondents performed piecemeal harvesting. Whenever farmers delayed the harvest, they risked severe damage of their sweet potato crops by weevils (Cylas spp., Coleoptera: Curculionidae) and millipedes (Diplopoda). Millipedes pierce and tunnel the storage roots, especially when harvesting is delayed. The farmers did not mention specific natural control agents for millipedes. Knowledge about pests was generally limited, so control strategies were poorly developed, understood and applied.

The maintenance and utilization of crop genetic diversity is important to ensure food security. The relative importance of yam and cowpea varieties and the influence of the socio-cultural and local economy context on the diversity maintained were analysed in Benin. Whereas the diversity is large, some varieties were rare, other ones on the way of being abandoned or already lost. Socio-cultural as well as economic and agronomic characteristics explained why some of them were still maintained. For example, the early-maturing yam variety Laboko was planted by most farmers to have tubers available in time for religious purposes, and some specific cowpea varieties played a role in the funeral of the parents in law. Farmers' preferences were translated into criteria they use to appreciate varieties. The diversity of the varieties sold on the market and their availability over time reflect farmers' strategies and conservation practices. The large price differences between varieties confirm the variation in quality as perceived by consumers. The most widely grown yam variety, Florido, is available on the market throughout the year but has a very low price. Market price differences among varieties are much smaller for cowpea than for yam. The processes of loss and displacement of some local varieties are described and the need for conservation is addressed. Different factors that may influence the level of varietal diversity in these crops, like the need to synchronize harvesting with high market prices, were analysed in depth. As opposed to mono-disciplinary approaches of scientists to farmers' problems and constraints, farmers show an inter- or trans-disciplinary behaviour and express their preferences through multi-criteria processes.