Browsing by Subject "Production"

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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.
Food-grade Lactobacilli expression systems for recombinant enzymes
(2013) Böhmer, Nico; Fischer, Lutz
Lactobacilli are Gram-positive bacteria used throughout the food industry as traditional starters for various fermented foods. Lactobacilli would be superior for recombinant enzyme production regarding the food safety demands since most of them are Generally Recognised As Safe (GRAS) organisms. The major advantages of Lactobacilli as food-associated microorganisms used for recombinant enzyme production are their safe and sustainable use as overall safety food-grade expression systems. In the work presented, Lactobacilli were studied in detail as food-grade expression systems for recombinant enzyme production. In a first analysis, the two pSIP expression systems, pSIP403 and pSIP409, were investigated to produce a hyper-thermophilic Beta-glycosidase (CelB) from Pyrococcus furiosus in Lactobacillus plantarum NC8 and Lactobacillus casei as hosts, respectively. Both Lactobacilli harbouring the pSIP409-celB vector produced active CelB in batch bioreactor cultivations, while the specific CelB activity of the cell-free extract was about 44% higher with Lb. plantarum (1,590 ± 90 nkatpNPGal/mgprotein) than with Lb. casei (1,070 ± 66 nkatpNPGal/mgprotein). A fed-batch bioreactor cultivation of Lb. plantarum NC8 pSIP409-celB resulted in a specific CelB activity of 2,500 ± 120 nkatpNPGal/mgprotein. A basal whey medium with supplements was developed as an alternative to the cost intensive MRS medium used. About 556 ± 29 nkat pNPGal/mgprotein of CelB activity was achieved in bioreactor cultivations using this medium. It was shown that both Lactobacilli were potential expression hosts for recombinant enzyme production. An additional approach was performed to produce a metagenome-beta-galactosidase using Lb. plantarum NC8 with the pSIP expression system. Using this system, a quite low maximal galactosidase activity of only 0.18 nkatoNPGal/mgprotein was detected. A 13 times higher activity of 2.42 nkatoNPGal/mgprotein was produced after the knock out of the interfering native Kluyveromyces lactis Beta-galactosidase in the well-known food-grade K. lactis pKLAC2 expression system. Nevertheless, the best performing expression system for the recombinant production of the metagenome-derived enzyme was the Escherichia coli BL21 strain with a pET vector, resulting in the highest Beta-galactosidase of 82.01 nkatoNPGal/mgprotein. Beside the use of the pSIP expression system, a novel expression system for Lb. plantarum was developed. This system is based on the manganese starvation-inducible promoter from the specific manganese transporter of Lb. plantarum NC8 which was cloned for the first time. The expression of CelB was achieved by cultivating Lb. plantarum NC8 at low manganese concentrations with MRS medium and the pmntH2-celB expression vector. A CelB activity of 8.52 µkatoNPGal/L was produced in a bioreactor. The advantages of the novel expression system are that no addition of an external inducing agent was required, and additionally, no further introduction of regulatory genes was necessary. The new promoter meets the general demands of food-grade expression systems. The glutamic acid racemase of Lb. plantarum NC8 was cloned and characterized in this work for the first time as a possible target for a food-grade selection system for this species. Glutamic acid racemases (MurI, E.C. 5.1.1.3) catalyse the racemisation of L- and D-glutamic acid. MurIs are essential enzymes for bacterial cell wall synthesis, which requires D-glutamic acid as an indispensable building block. Therefore, these enzymes are suitable targets for antimicrobial drugs as well as for the potential design of auxotrophic selection markers. A high expression system in E. coli BL21 was constructed to produce and characterize the biochemical properties of the MurI from Lb. plantarum NC8. The recombinant, tag-free Murl was purified by an innovative affinity chromatography method using L-glutamic acid as the relevant docking group, followed by an anion exchange chromatography step (purification factor 9.2, yield 11%). This two-step purification strategy resulted in a Murl sample with a specific activity of 34.06 µkatD-Glu/mgprotein, comprising a single protein band in SDS-PAGE. The purified Murl was used for biochemical characterization to gain in-depth knowledge about this enzyme. Only D- and L-glutamic acid were recognised as substrates for the Murl with similar kcat/Km ratios of 3.6 sec-1/mM for each enantiomer. The findings in this study may contribute to further development and implementation of food-grade Lactobacilli expression systems for recombinant enzyme production. Furthermore, the results obtained may help to optimise and select hosts and expression systems for industrial enzyme production for the needs of the food industry.
Genetic and phenotypic correlations among feed efficiency, immune and production traits in indigenous chicken of Kenya
(2023) Miyumo, Sophie A.; Wasike, Chrilukovian B.; Ilatsia, Evans D.; Bennewitz, Jorn; Chagunda, Mizeck G. G.
This study aimed at estimating genetic and phenotypic relationships among feed efficiency, immune and production traits measured pre- (9–20 weeks of age) and post- (12 weeks from on-set of lay) maturity. Production traits were average daily gain (ADG) and average daily feed-intake (ADFI1) in the pre-maturity period and age at first egg (AFE), average daily feed-intake (ADFI2) and average daily egg mass (EM) in the post-maturity period. Feed efficiency comprised of residual feed intake (RFI) estimated in both periods. Natural antibodies binding to keyhole limpet hemocyanin (KLH-IgM) and specific antibodies binding to Newcastle disease virus (NDV-IgG) measured at 16 and 28 weeks of age represented immune traits pre- and post-maturity, respectively. In the growing period, 1,820 records on ADG, KLH-IgM and NDV-IgG, and 1,559 records on ADFI1 and RFI were available for analyses. In the laying period, 1,340 records on AFE, EM, KLH-IgM and NDV-IgG, and 1,288 records on ADFI2 and RFI were used in the analyses. Bi-variate animal mixed model was fitted to estimate (co)variance components, heritability and correlations among the traits. The model constituted sex, population, generation, line and genotype as fixed effects, and animal and residual effects as random variables. During the growing period, moderate to high heritability (0.36–0.68) was estimated for the production traits and RFI while the antibody traits had low (0.10–0.22) heritability estimates. Post-maturity, the production traits and RFI were moderately (0.30–0.37) heritable while moderate to high (0.25–0.41) heritability was estimated for the antibody traits. Genetic correlations between feed efficiency and production traits in both periods showed that RFI had negative genetic correlations with ADG (−0.47) and EM (−0.56) but was positively correlated with ADFI1 (0.60), ADFI2 (0.74) and AFE (0.35). Among immune and production traits, KLH-IgM and NDV-IgG had negative genetic correlations with ADG (−0.22; −0.56), AFE (−0.39; −0.42) and EM (−0.35; −0.16) but were positively correlated with ADFI1 (0.41; 0.34) and ADFI2 (0.47; 0.52). Genetic correlations between RFI with KLH-IgM (0.62; 0.33) and NDV-IgG (0.58; 0.50) were positive in both production periods. Feed intake, RFI and antibody traits measured in both production periods were positively correlated with estimates ranging from 0.48 to 0.82. Results from this study indicate selection possibilities to improve production, feed efficiency and immune-competence in indigenous chicken. The genetic correlations suggest that improved feed efficiency would be associated with high growth rates, early maturing chicken, high egg mass and reduced feed intake. In contrast, improved general (KLH-IgM) and specific (NDV-IgG) immunity would result in lower growth rates and egg mass but associated with early sexual maturation and high feed intake. Unfavorable genetic correlations between feed efficiency and immune traits imply that chicken of higher productivity and antibody levels will consume more feed to support both functions. These associations indicate that selective breeding for feed efficiency and immune-competence may have genetic consequences on production traits and should therefore be accounted for in indigenous chicken improvement programs
Simultaneous lotsizing and scheduling - extensions and solution approaches
(2018) Wörbelauer, Martin; Meyr, Herbert
The present thesis focuses on simultaneous lotsizing and scheduling. A comprehensive review of the literature is presented in which the historical development of the subject and the current research gaps are, based on a classification scheme, described. Additionally, a review focusing on so-called „secondary resources“ (e.g., setup operators or raw materials), which are considered alongside the primary production resource, is provided. The insights on different types of secondary resources help to develop a new model formulation generalizing and extending the currently used approaches, which are specific to certain settings. Some illustrative examples demonstrate the functional principle and flexibility of this new formulation which can thus be used in a wide range of applications. Finally, a new heuristic to solve large-scaled simultaneous lotsizing and scheduling problems is presented. The heuristic creates a modified multi-line master problem by aggregating products into groups. The resulting problem is less complex and its solution can be used to define single-line sub problems. These sub problems are solved by heuristics present in the literature and the results are then combined to form a solution to the original problem. Numerical tests show the applicability of the aforementioned approach to solve problems of practical relevance.