Browsing by Subject "Produktionssystem"

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    Agronomic strategies to reduce potential precursors of acrylamide formation in cereals
    (2020) Stockmann, Falko; Graeff-Hönninger, Simone
    Food safety is of great importance as harmful substances formed during food processing can negatively affect human health. When the carcinogenic food ingredient acrylamide (AA) accidentally appeared in 2002, it was not expected that AA would take this much attention during the next years. Yet, after around 15 years of research, AA has finally been recognized as being harmful. In a first step, research focussed on food processing implications on AA formation. The impact of heat treatment, time of heating, baking agents, fermentation time, additives and enzymes were reported in several studies. Nevertheless, since 2011 food AA levels seem to stagnate or even increase in some years. Thus, the food industry did not show sufficient progress in reducing AA. Reducing sugars and amino acid free asparagine (Asn) are the main AA precursors. They can fluctuate in their content for instance in grain flour or potatoes shifting the focus of AA origin to the raw material. Thus, the production of raw material low in AA precursors seems important. However, lowering precursors of AA in the raw material necessitates suitable agronomic strategies to grow cereal species and cultivars low, especially in free Asn. Hence, the major goal of this thesis was to investigate the following questions concerning their impact on free Asn formation in cereals: 1. Which role does the management system plays, as organic vs. conventional farming systems highly differ in their cropping strategies? 2. What is the best nitrogen fertilization strategy when comparing organic vs. conventionally cropping systems? 3. Is there an impact of sulphur fertilization concerning sulphur amount and sulphur type? 4. Can expanding row distance and lowering seed density in low-input farming systems positively influence baking quality while keeping free Asn amounts low? 5. For organically grown cereals no level of free Asn was available. Thus, the question came up to which extent organically grown cereal species and cultivars including ancient grains like einkorn and emmer differ in free Asn. 6. Should free Asn be implemented in breeding programs if heritability is high? 7. Is there an impact of harvest timing on free Asn formation? Out of several field trials the following results were obtained: • The cropping system had a significant impact on grain yield, the level of free Asn and quality traits. Across all species, free Asn contents in flour were 26% lower under organic conditions compared to conventional farming. For wheat a maximum reduction of 50% in free Asn content was possible if organically produced. Spelt and rye were affected to a minor extend as only in single years organically grown cultivars showed up to 33% lower Asn contents. • Nitrogen (N) fertilization significantly influenced grain yield and baking quality in both cropping systems. In contrast, up to a certain amount of N free Asn was only affected to a minor extend. In particular, within the organic farming samples no significantly higher free Asn amounts were determined even if N fertilizer was raised or the N form was changed. A late N fertilization within the conventional cropping system increased crude protein content, while no clear effect was found on free Asn. Also, cultivars affected free Asn level significantly. Wheat cultivar Capo exhibited the lowest AA formation potential at a N supply of 180 kg N ha−1 while simultaneously reaching a crude protein content > 15% (conventional) and > 12% (organic). Thus, lowering free Asn by adjusting N treatments should not necessarily affect baking quality. In general, free Asn amounts in wheat varied widely both within cultivars and between cropping systems. Besides N, neither type nor amount of sulphur fertilization influenced free Asn significantly. • Extending row distance can increase quality traits protein and sedimentation value. Seed density was highly related to grain yield and test weight. Most importantly, free Asn was only minor affected by both treatments. Thus, larger row distances can be recommended to raise baking quality in organic farming systems without simultaneously affecting free Asn. Number of grains spike-1 seems to be related to free Asn (R2=0.72). This provides new insights on Asn synthesis during grain development and offers the opportunity to predict free Asn formation without expensive chemical analyzes. In contrast Asn and protein content did not show any relation while high protein contents in grain seem to lower AA amount in heated flour samples. • The impact of organically grown cereal species and cultivars in combination with marginal N supply on free Asn was clearly shown. A reduction potential of 85% was reached if rye was replaced by spelt. Surprisingly, the ancient species einkorn and emmer reached a very high free Asn content similar to rye. Heritability was high for wheat and spelt concerning locations, while regarding years, heritability was low for wheat but high for spelt and rye. For organically grown cereals, the relation between free Asn and AA formation was proven. Across species and years free Asn can serve as an indicator for AA formation (R2 of 0.69). • Harvest timing affects free Asn levels. In this context a delayed harvest can increase Asn significantly while shifting harvest 1-2 weeks earlier decreased Asn by up to 60% depending on cereal species and cropping system. After summarizing and stating the most promising steps in the frame of agronomic strategies to lower free Asn, a prediction tool for free Asn should be implemented that classifies the impact of agronomic strategies and leads to recommendations to farmers. Finally, the main riddle, that should be solved during the next studies is the question, why cereal species and cultivars differ in their Asn formation. This thesis gives some preliminary ideas but a much deeper insight is essential to establish long-term strategies to lower free Asn content.
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    Breeding objectives and selection schemes for Boran cattle in Kenya
    (2009) Rewe, Thomas; Valle Zárate, Anne
    Beef production with Boran cattle of Kenya presents an opportunity for utilising the potential of an indigenous breed. Improving the performance of these cattle through production of quality breeding stock may support the livelihoods of Boran cattle farmers. Organised breeding programmes for Boran cattle in Kenya are lacking. This thesis focussed on the design of optimal genetic improvement programmes for Boran cattle raised in the semi-arid tropics of Kenya. Specifically, the aims were: 1) to review the potential for beef cattle genetic improvement in sub-Saharan Africa, 2) to describe the state of institutional framework supporting Boran breeding in Kenya while considering the different categories of Boran cattle farmers, 3) to investigate the genetic and economic merit of alternative breeding programmes based on improved Boran, the unimproved Boran and the possibilities of expanding an inclusive breeding programme for these two strains of Boran cattle, 4) to discuss the feasibility of alternative breeding strategies within the context of a formal breeding programme in Kenya. The methodological approach entailed a review of the literature on cattle production and genetic improvement strategies for sub-Saharan Africa. This was done by identifying previous and on-going breeding activities among indigenous cattle breeds based on their regional distribution in Africa. An institutional framework analysis to characterise the Boran breeding sector in Kenya was also performed. Open questions were presented to the Boran cattle Breeders? Society of Kenya through an online survey to ascertain the structure of the society in terms of membership, cattle populations and animal breeding activities. The production systems, cattle types and breeding objectives were also sought from previous studies on Boran cattle in the process of developing appropriate breeding programmes. Design and evaluation of nucleus breeding programmes (genetically and economically) was done with the ZPLAN computer programme by defining the breeding objectives and selection criteria traits, describing breeding and commercial populations, describing selection groups as well as their reproduction performance parameters. The costs of the breeding programme included fixed costs and costs of animal recording. To account for genetic gain and the flow of animal genetics, a gene transmission matrix was defined utilising the selection groups alongside genetic and phenotypic parameter matrices. The information sources for the selection criteria were mainly parental selection groups and halfsibs of animal. The number of animals forming the selection groups and information sources was calculated in the NBILD and NUMBER subroutines of the ZPLAN. The interest rates for returns and costs were 8% and 6% respectively while the investment period was set at 25 years. The scope of the study was limited to two classes of farmers keeping Boran, the commercial beef ranchers and the market-oriented low-input beef producers that interact with commercial beef ranchers. Three breeding objectives were evaluated, 1) conventional breeding objectives with market (economic) values derived from bio-economic modelling, namely: direct sale weight, dressing percentage, consumable meat percentage, cow weaning rate, cow survival rate, cow weight, age at first calving, milk yield, feed intake and post weaning survival rate, 2) a combination of selected conventional target traits in addition to traits important to low-input farmers to exploit the ongoing informal interaction between the large scale ranchers and low-input systems, and 3) trait preferences for low-input farmers derived from conjoint analysis studies namely; sale weight, calving interval, temperament, tick resistance, trypanotolerance and lactation milk yield. To evaluate the benefit of perceived trypanotolerance in unimproved low-input herds, strategic recording for trypanotolerance for offspring of nucleus sires born in these herds was assumed. Closed and open-nucleus types were evaluated and variations on the nucleus size (5%, 10% and 25%). proportion of gene transfer to commercial herds (25%, 50%, 70%) and the proportion of gene importation into the nucleus (10%, 20% and 30%) were tested. The results from the institutional framework analysis showed that the Boran sector is structured with a section of the farmers being large scale commercial ranchers keeping approximately 17% of a total population of 580,000 heads of cattle. The rest were Boran farmers operating in low-input production systems keeping over 80% of the total population. The large scale commercial ranchers were found to be divided into two groups, about 52% of these farmers were elite breeders that record with the Kenya Stud Book and the rest were mainly commercial. The large scale commercial ranchers keep the improved Boran while the low-input farmers keep the unimproved Boran. The large scale commercial ranchers were organised into a breed society, namely, the Boran Cattle Breeders Society (BCBS), incorporating both the elite breeders and the commercial group. The BCBS was identified as a key stakeholder in the breeding of Boran cattle because of their informal role as suppliers of breeding stock. The results from the evaluation of alternative open and closed-nucleus breeding programmes utilising the Boran cattle populations were obtained with the ZPLAN computer programme. For the elite breeders?, where a total population of 52,000 cows with a breeding unit of 25% was assumed, the overall monetary genetic gain was KSh86 per cow while the profit per cow was KSh361 under the conventional breeding objective. The breeding programme with the entire BCBS group where a population of 99,972 cows was assumed obtained a higher monetary genetic gain and profit than the elite group per cow of KSh93 and KSh431 respectively under the same breeding objective. The results revealed the effect of a larger effective population size on performance of breeding programmes. The breeding programme based wholly on market oriented low-input producers was evaluated using farmer trait preferences as the breeding objective. This breeding programme posted a negative gain for milk yield of -1.1 kg, which improved when restrictions on growth and adaptation were applied. The introduction of the combined breeding objective that included adaptation and disease tolerance traits resulted in a drop in sale weight gain by almost 2 kg. However, post-weaning survival rate improved from 0.4% to 1% and trypanotolerance gained 20% packed cell volume within this breeding objective. There was reduction in feed intake under the combined breeding objective, which is desirable considering the prevailing limitations on land, feed and climatic conditions. This may induce a change in focus from the continuous improvement in sale weight. The gains in post weaning survival rate would support this objective. The results from the expanded breeding programme may be beneficial to both the low-input farmers and the commercial ranchers because of the advantages conferred from the improvement in adaptation traits. The benefits of extra recording for trypanotolerance in the commercial herds of the expanded programme were not realised. In general, the open-nucleus programmes were superior genetically while the closed-nucleus programmes were superior economically. The larger nucleus sizes (25%), higher gene contributions to commercial herd (70%) and limiting nucleus opening to 10% were most profitable. The limitations of the study were observed from the online interviews with respect to the amount of information that could be retrieved from key persons. Similarly, information on the legal framework of the breeding sector was scarce since Kenya has no active livestock breeding policy. The design and evaluation of the breeding programmes was possible with ZPLAN, however, in this study, genetic variance for traits, which normally diminishes with selection and inbreeding, was not account for. This may have had implications related to overestimation of genetic response and economic returns. Nonetheless, the potential of the Boran for both beef production and fitness traits coupled with the presence of institutional support for animal recording in Kenya were evaluated as strengths of the system. This study has shown the possibilities of combining market and non-market traits useful in breeding programmes for cattle utilised in different production systems. This approach is useful in cases where interactions exist between different categories of farmers. To benefit from advantages offered by open-nucleus breeding, recording may be avoided in the commercial herds and selection be done under criteria that are acceptable by the farmers. Further investigations on farmer organisations and comprehensive livestock breeding policies may aid the process of establishing co-ordinated breeding programmes for Boran cattle in Kenya.
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    Development potential of smallholder livestock production in Zambia
    (2019) Lubungu, Mary; Birner, Regina
    The continued increase in the demand for livestock products in Africa presents a development opportunity for smallholder livestock farmers. If this opportunity is harnessed well, it can contribute to rural poverty reduction. However, translating this opportunity into reality requires unlocking smallholder farmers productivity potential, considering that livestock performs numerous functions beyond just serving as an income source. To support this development opportunity for smallholder livestock farmers, it is essential to enable a large share of small-scale farmers to engage in livestock farming and increase the productivity of smallholder livestock farming systems in an equitable and environmentally sustainable way. Taking Zambia as an example, this thesis aims to identify and analyze factors that have been obstacles to livestock development. Based on two rounds of panel data collected from smallholder farm households in Zambia, it was observed that the share of farmers who keep cattle is limited and that farmers move in and out of cattle production, despite the many benefits that livestock offers. Therefore, there is a need to identify what enables and disables farmers to keep livestock. There is also a need to identify the driving factors of livestock herd growth since small herd size is one factor that prevents farmers from participating in the market for livestock products. To better understand how livestock production systems can be developed equitably, it is also necessary to understand the gender dimensions of livestock farming to ensure that women will not be left out of the growth process. Moreover, to be able to support livestock production effectively, it is also essential to identify the governance challenges that are likely to occur in the implementation of livestock development interventions. Against this backdrop, the thesiss overall goal was to identify options to promote sustainable livestock production systems. The thesis focused on cattle, which is the most valuable large asset among smallholder farmers in Zambia. The thesis had four specific objectives, which are addressed in separate chapters: (i) To unravel the mystery of moving in and out of cattle keeping; (ii) to identify the factors determining the livestock herd size among smallholder farmers in Zambia; (iii) to understand the gender dimensions in cattle production; and (iv) To uncover the governance challenges of implementing the vaccination campaigns in Zambia To achieve these objectives, a mixed-method research approach was used, involving both quantitative and qualitative methods. The quantitative analysis was based on an existing household survey data set, which is representative at the national level. Various econometric techniques were applied, including probit, correlated random effect, and zero-one inflated beta regressions. For the qualitative component of the study, a combination of empirical data collection methods was applied, which included focus group discussions, individual household in-depth interviews, key informant interviews, and a participatory mapping method called Process-Net-Map. Analytical methods for the qualitative component of the study included content analysis as well as causal narratives. The analysis showed that moving in or out of cattle production is influenced by human population growth, climatic variability, livestock population density, male household labor availability, and institutional support. The findings indicate that household-level factors and regional factors and their interaction influence households ability to take up cattle production and continue this activity over time. One can derive from this analysis that regional incentives, such as an increase in the demand for draft power, are important to encourage cattle production, but household level challenges, such as labor availability, need to be addressed, as well. The analysis also indicated that loss of cattle due to death, rather than cattle sales, was a major reason for the reduction in herd size. Mortality rates were found to be responsive to animal health interventions, which underlines the need for effective animal health services as a precondition for improved productivity in livestock production. The analysis also showed that farmers mainly increased their herd size by keeping the off-spring of their herd rather than by buying animals. Low conception rates due to limited feed resources during the dry season were identified as a major obstacle to a faster increase in herd size. Farmers who were able to enter into cattle production typically used their income from crop farming to acquire the first stock. This finding indicates that, in the absence of well-functioning rural financial markets, smallholders who cannot generate a surplus from crop farming will not be able to move into cattle production. The analysis also threw light on the factors that enable women to own cattle. These factors included financial independence and the accumulation of other assets. Women were also more likely to own cattle in households with larger herd sizes. Perceived intra-household conflicts were identified as an obstacle to female cattle ownership. Considering the important role of livestock support programs, an in-depth analysis of a program was carried out that supported livestock vaccination campaigns. The Process Net-Map method served to identify the governance challenges faced by the program. The findings established that the complexity of the procurement procedure, the limited capacity of the central actors, and a lack of urgency from influential actors resulted in procurement delays, and a diversion of funds caused delays in the release of funds. Lack of influence by the farmers also contributed to the inefficiency of the implementation procedure. The findings are likely to be relevant for implementing other livestock development programs that involve the distribution of publicly procured inputs. Overall, it was concluded that the problems identified in the thesis need to be addressed. Otherwise, smallholder livestock farmers will not be able to exploit the opportunity of rising demand for livestock products. A number of policy recommendations were derived from the findings. These include the provision of institutional and technical support for the intensification of smallholder cattle production, strategies to bridge the gender gap in cattle production in a way that does not result in household conflicts; and innovative approaches to improve the efficiency in the implementation of livestock development programs.