Evaluation of agro-industrial by-products as protein sources for duck production in the Mekong Delta of Vietnam

This thesis is based on four studies to determine the nutritive value and ileal and total tract amino acid digestibility of agro-industrial by-products, and the effects of inclusion of these by-products in diets on the biological performance of growing crossbred Muscovy and common ducks in the Mekong Delta, Vietnam. The results show that brewery waste (BW) was characterised by high protein content,good balance of essential amino acids, but high crude fibre content. The best growth performance was observed when 50% of the concentrate was replaced by BW for both Muscovy and common ducks. The crossbred Muscovies had better performance and gave higher economic benefit than the local Muscovies, and common ducks gave the lowest profit. BW could be offered either in mixed or separate feeding systems without any effects on performance and carcass yield (Paper I and II). Soya waste (SW) and ensiled shrimp waste (ESW) are good protein sources, but low in dry matter (DM) and methionine content (SW) and high in chitin content (ESW). The best performance in terms of growth rate and carcass quality was found with replacement of up to 60% of soybean meal by SW, and only 20% of fish meal by ESW, which gave the lowest feed costs (Paper III). The inclusion of ESW in diets for adult crossbred common ducks resulted in a linear decrease of the apparent total tract digestibility of dry matter, organic matter, ether extract, N free extract and N retention with increasing levels of ESW. The digestibility of individual amino acids followed a similar pattern to the nutrient digestibility. The apparent total tract digestibility of most individual amino acids was higher than the apparent ileal value (Paper IV). It can be concluded that from nutritive and economic apects the three agro-industrial byproducts evaluated have proven to be acceptable feed ingredients in duck diets. Replacement up to levels of 20% (ESW), 50% (BW) and 60% (SW) of fish meal, concentrate and soybean meal, respectively, in diets for growing crossbred ducks can be recommended under the conditions of the Mekong Delta

Structure learning of undirected graphical models for count data

Biological processes underlying the basic functions of a cell involve complex interactions between genes. From a technical point of view, these interactions can be represented through a graph where genes and their connections are, respectively, nodes and edges. The main objective of this paper is to develop a statistical framework for modelling the interactions between genes when the activity of genes is measured on a discrete scale. In detail, we define a new algorithm for learning the structure of undirected graphs, PC-LPGM, proving its theoretical consistence in the limit of infinite observations. The proposed algorithm shows promising results when applied to simulated data as well as to real data

Evaluation of organochlorinated pesticide residue in the water of Ba Tri agricultural canal Ben Tre province

The residues of Organochlorine pesticides from the water of the agricultural canal and river in Ba Tri district, BenTre province were determined by gas chromatography with electron- capture detector. The solid phase extraction (SPE- C18) cartridge was applied to extract organochlorine pesticides residues in water samples. The samples were collected during the dry, wet season and the crop growing 2006-2007. The results showed that most of water samples were contaminated with pesticide at concentration from 0.01 to 2.00 ppb. The residue of pesticides in water mainly depended on the crops season and have highest value in the beginning of growing period. The concentration of pesticides residues decreased from rice- field to canal and river. There were many forbidden pesticide such as HCH, Endosulfan, Heptachlor, Dieldrin etc. have been found with high frequency in water. It causes a big risk for human heath and aquatic biota

Agri-Food Value Chain Performance during the COVID-19 Pandemic: An Empirical Study of Chu-mango Business Linkages in Dong Thap, Vietnam

This study aims to identify important factors that directly influence value chain performance (quality, responsiveness, flexibility and efficiency), which are explained by value chain integration (collaboration, commitment, coordination and joint decision-making) in the case of unexpected risk (the COVID-19 pandemic). This study contributes to maintaining the business linkage model among farmers – cooperatives – enterprises in the caseof the COVID-19 pandemic and quickly recovering after the COVID-19 pandemic. Structural equation modelling (SEM) was used for data analysis following an iterative process based on theoretical and empirical analyses toobtain a structural model fit and test the research hypothesis. The findings indicate that the VCI positively influenced the VCP of Chu-mango business linkages at the 1% significance level through coordination (Beta = 0.345;construct reliability (CR) = 3.272), collaboration (Beta = 0.289; CR = 3.128), and joint decision-making (Beta = 0.324; CR = 3.245). This study provides empirical data on the relationship between VCI and VCP through the Chu -mango value chain in Dong Thap Province during the COVID-19 pandemic to raise awareness from stakeholders and encourage value chain thinking to improve performance. This result may pave the way for relevant policymakers to look for policies and strategies for better inclusiveness of stakeholders to show the importance of the VCI in improving the performance. Moreover, the study is an empirical case contributing to the agribusiness value chain in a developing country; it applies the agribusiness value chain of the tropical fruit domain and can be used for otheragricultural products in other cases of unexpected risks

Optimal condition for Propagation and Growing of Dendrobium thyrsiflorum

Dendrobium thyrsiflorum is a medicinal orchid that is being gradually destroyed due to over-exploitation. This research focuses on in vitro production of D. thyrsiflorum plantlet under optimal acclimatization conditions. The results of the study showed that the best medium for seed germination was MS basal medium (full-strength MS nutrient plus 100 ml L-1 coconut water; 7 g L-1 agar, 30 g L-1 sucrose, and 0.5 g L-1 active charcoal) supplemented with 60 g L-1 mashed sweet potatoes, which induces 97.8% of seed germination. The shoot was well developed in MS basal medium supplemented with 60 g L-1 mashed sweet potatoes and 0.4 mg L-1 6-Benzylaminopurine (BA) and, corpulent and green in shoot morphology. The shoot multiplication rate was greatest on MS basal medium supplemented with 0.4 mg L-1 BA and 0.4 mg L-1 Kinetin with 4.53 times, and the shoot height was reported at 3.45 cm after 8 weeks of subculture. Further, The shoot was 100% rooting, with an average of 4.51 roots/shoot and 5.34 cm per root in length when the shoot was implanted on MS basal medium plus 60 g L-1 mashed sweet potatoes and 0.75 g L-1 active charcoal. Especially, plantlets after transplanting to the orchid net house reached a 94.8% survival rate on tree fern after 24 weeks. Hence, the results of the study suggested a successful production of D. thyrsiflorum plantlet on the selected media compositions