Effect of urea-molasses-treated highland bamboo leaves supplementation on lactating crossbred dairy cows nutrient utilization, body weight, milk yield and its composition and economic performance under on-farm condition in Guagusa Shikudad district, Ethiopia.

BACKGROUND: In Ethiopia, locally available feed resources are commendable in livestock production to make the sector sustainable and productive. OBJECTIVES: This on-farm evaluation was conducted to evaluate the effect of urea-molasses-treated highland bamboo (Yushania alpina) leaves (UMTHBL) in lactating crossbred dairy cows' nutrient utilization, body performance, milk yield and quality and economic performance. METHODS: On-farm feeding trial was conducted using 12 lactating cows with initial body weight (328.08 ± 0.98 kg), initial milk yield (3.14 ± 0.78 L) of uniform parity (2) and stage of lactation (early) using a Randomized Complete Block Design. Three dietary treatments, namely, 6 h grazing (control) + concentrate (T1), control + UMTHBL ad lib (T2), control + untreated BL adlib (T3) with three replications were used. Analysis of variance was employed for the feeding trial data analysis. RESULTS: The UMTHBL increased more dry matter and nutrients intake than untreated. A significant difference (p < 0.05) was recorded between UMTHBL feeding (T2) and T1 and T3 in terms of increased milk yield. The highest (6.26 L) and the lowest (3.27 L) mean milk yield per day were recorded for cows fed UMTHBL and the control group, respectively. Urea-molasses treatment improved the crude protein (CP) and reduced fibres content than untreated. Treatment effects were not-significant (p > 0.05) for milk compositions. Similar to milk yield, dairy cows in T2 consumed more CP which is also reflected in higher body weight and economic benefit. CONCLUSION: It can be concluded that employing treatment technology for highland bamboo leaves could support the crossbred dairy cows' production in smallholder farmers.

Integrating knowledge on biophysical and socioeconomic potential to map clusters for future milk production in Ethiopia.

Despite growing milk demand and imports, market-oriented milk production and formal processing in Ethiopia is limited to areas around Addis Ababa, notwithstanding its competing land use demand. This study assessed biophysical and market potential for developing the dairy sector, characterizing Ethiopian dairy clusters. Biophysical data from geographic information system (GIS) sources and information from key informants were combined in mapping and ranking these clusters on milk production potential. Twenty-four indicators in six major categories were applied for this assessment: feed availability, environmental conditions for dairy cattle, current production status, access to inputs and services, output market access, and production expansion potential. Feed availability (fodder, crop residues, and agro-industrial by-products as well as land availability and affordability) were the main drivers for dairy development, followed by the current production status, mainly driven by number of (improved) dairy cattle and (formal) milk volumes. Dairy clusters close to Addis Ababa had the highest overall scores for development potential, mainly determined by local demand and access to inputs. For dairy sustainable dairy development in Ethiopia, companies seeking long-term opportunities may avoid the Addis Ababa area and develop dairy production and processing in other clusters especially in Amhara and Tigray regions, with good milk production potential but less developed market infrastructure. The combination of biophysical data and key informant knowledge offered key strengths in delivering valuable results within a short time span. It however requires a careful selection of knowledgeable key informants whose expertise cover a broad scope of the dairy value chain.

Metal availability in a highly contaminated, dredged-sediment disposal site: field measurements and geochemical modeling.

Two complementary approaches were used to characterize arsenic and metal mobilizations from a dredged-sediment disposal site: a detailed field study combined with hydrogeochemical modeling. Contaminants in sediments were found to be mainly present as sulfides subject to oxidation. Secondary phases (carbonates, sulfates, (hydr)oxides) were also observed. Oxidative processes occurred at different rates depending on physicochemical conditions and contaminant contents in the sediment. Two distinct areas were identified on the site, each corresponding to a specific contaminant mobility behavior. In a reducing area, Fe and As were highly soluble and illustrated anoxic behavior. In well-oxygenated material, groundwater was highly contaminated in Zn, Cd and Pb. A third zone in which sediments and groundwater were less contaminated was also characterized. This study enabled us to prioritize remediation work, which should aim to limit infiltration and long-term environmental impact.

Operator-splitting-based reactive transport models in strong feedback of porosity change: The contribution of analytical solutions for accuracy validation and estimator improvement.

Reactive transport is a highly non-linear problem requiring the most efficient algorithms to rapidly reach an accurate solution. The non-linearities are increased and the resolution is even more demanding and CPU-intensive when considering feedback of dissolution or precipitation reactions on hydrodynamic flow and transport, commonly referred to as the variable porosity case. This is particularly true near clogging, which leads to very stiff systems and therefore small time-steps. The operator-splitting approach often cited is a widely use method to solve these problems: it consists in solving sequentially the transport then the chemistry part of the problem. Operator-splitting appears to be an accurate approach, provided that the solution is iteratively improved at each time-step. The paper details analytical solutions and test-cases for this class of problems. They demonstrate that iterative improvement is then compulsory. They also helped develop an improved estimator/corrector method which allows to reach convergence faster and to reduce stiffness. The efficiency improvement is significant as illustrated by an example of carbonation of a cement paste, a well-known problem that leads to complete clogging of the interface layer.