Ethiopian Journal of Biological Sciences

Variation of carbon pool along vegetation types: A case study in the Hallaydeghi-Asebot National Park, Eastern Ethiopia

2025-06-02T11:06:34+00:00

Estimating carbon stocks of protected areas is essential for improved understanding of carbon cycle; however, studies in the Hallaydeghi-Asebot National Park (HANP) are lacking. Thus, this study was aimed to estimate the potential reservoir of carbon in the HANP and its’ variation across three vegetation types (woodland, grassland, and bushland). The variations in soil organic carbon stock density, aboveground and below ground biomass and carbon, and litter biomass and carbon pools were estimated from data collected from sixty, 30 m x 30 m area sample plots. Due to non-normal distribution of data for LHG carbon stock, the non-parametric Kruskal-Wallis test was used to examine the effect of vegetation type, followed by Mann-Whitney U test for pair-wise comparisons between vegetation types. Results showed that total mean carbon stock of HANP in 2019 was estimated at 56.73 ± 3.25 t C per ha, with 208.20 ± 11.92 CO₂ equivalents. Soil organic carbon stock contributed significantly greater proportion (74%) to the total carbon stock of the study area compared with that by biomass carbon. The proportion of carbon stock allocation in the different pools of each vegetation type was in the order of: SOCD > AGB > BGB > LHG. Although the mean total carbon stock was similar among vegetation types, the mean soil organic carbon stock density was significantly varied among vegetation types. Soil carbon and aboveground carbon pools are the dominant contributors to the total carbon stock of HANP. Thus, carbon management efforts in the area should focus on soil preservation, reduction of vegetation destruction and assisting regeneration.

Utilization of azolla as a sustainable supplement for fish feed: Cultivation, nutritional analysis, and feeding trial study

2025-06-02T11:45:45+00:00

Cultivation of Azolla filiculoides Lam. and feeding effect on the growth performance and survival rate of Nile tilapia (Oreochromis niloticus L., 1783) was evaluated at the Bahir Dar Fisheries and Other Aquatic Life Research Centre. The study involved Azolla cultivation for fish growth for 80 and 60 days, respectively. It was found that cow dung was optimal for A. filiculoides growth, yielding nutrient concentrations of 13.8 mg/l (PO₄) and 4.4 mg/l (NO₃). This Azolla species shows potential as an unconventional feed for Nile tilapia, with T1 (cow dung) producing the highest fresh green biomass (9.66 kg/m²) and dry biomass (0.54 kg/m²). In T2, using inorganic fertilizer (NPS), the average yield was 6.7 kg/m² of fresh green biomass and 0.38 kg/m² of dry biomass. T3 (control), without fertilizer, yielded the least (1.48 kg/m² fresh and 0.07 kg/m² dry biomass). Sun-dried A. filiculoides had average percentages of dry matter content (90%), organic matter (73.33%), crude protein (21.29%), ether extract (4.1%), crude fiber (10.3%), nitrogen-free extract (NFE) (47.6%), and acid detergent fiber (ADF) (28.89%), with a total ash content of 16.67%. Furthermore, Nile tilapia fed on fresh green Azolla exhibited improved final weight, total weight gain, daily growth rate and specific growth rate. Significant differences (P<0.05) in feed conversion ratios (FCR) were observed among treatments. Nile tilapia fingerlings had a higher survival rate of 96% when fed solely on fresh green Azolla meal, in contrast to an 85% survival rate with dry Azolla meal, whereas the control group maintained a 100% survival rate. Overall, incorporating A. filiculoides into formulated or commercial fish diets could enhance their performance.

Population density, feeding, and reproductive ecology of small mammals in Wenchi Montane Forest, Central Ethiopia

2025-06-02T11:57:31+00:00

Studying the ecology of small mammals is extremely important in order to know their ecological roles in their natural habitats. A study was conducted to obtain information about the density, feeding habits and reproduction of small mammals in the Wenchi highlands between the year 2019 and 2021. Small mammals were trapped from four natural forests, woodland, and a shrubland using Sherman live-traps (for stomach content analysis) and snap traps (for embryo count) in standard trapping grids. Data were analyzed using descriptive statistics and the Chi square test. A total of 15 small mammal species were live and snap-trapped – 12 rodent and 3 shrew species. Small mammal density and biomass varied among species, seasons and habitat types (p<0.05). Stenocephylems albipes had the highest population density (23.45 ha^-1 ), while Lophiomys imhausi had the least (0.5 ha^-1 ). Small mammals had a higher density during the dry (83.33 ha^-1 ) than wet (59.35 ha^-1 ) season. The highest density (135.71 ha^-1 ) was registered in Lakeshore forest, whereas the lowest (15.30 ha^-1 ) was from Erica forest. Most rodents were mature and reproduced throughout the year. However, more pregnant females were recorded during the wet (25) than the dry (13) season. The number of embryos counted also varied among species and seasons (p<0.05). Most rodent species displayed omnivorous feeding habits. However, plants (71.1%) had the highest proportion than animal matters (19.69%). Small mammals in Wenchi forest remnants displayed a low population density, omnivorous feeding habits and varying reproductive patterns suggesting urgent conservation interventions in the area.

Evaluation of locally formulated feed on the growth performance and survival rate of Nile tilapia (Oreochromis niloticus) in an aquarium

2025-06-02T12:13:38+00:00

A 90-day feeding trial was conducted at the Bahir Dar Fisheries and Aquatic Life Research Centre to develop a nutritionally optimized feed for Nile tilapia using locally available ingredients and to evaluate its impact on the fish's growth and survival rates. The study tested three locally formulated diets alongside a commercial feed (control). The test diets were prepared using soybeans, lupine (Lupinus albus), and cowpeas as primary protein sources. A total of 168 mixed-sex Nile tilapia fingerlings (average weight 17.23 ± 0.32 g) were randomly divided into three groups (triplicates per treatment) and housed in 12 rectangular glass aquariums (dimensions: 90 x 45 x 44 cm, 180 L), set up with a recirculating water system and no substrate. Each aquarium was stocked with 14 fingerlings. Fish were fed at 5% of their body weight twice daily, at 9:00 AM and 3:00 PM. Bi-weekly sampling was conducted to monitor growth, and daily observations recorded mortality. The results showed a significant difference (p<0.05) in the growth performance of Oreochromis niloticus across the four diets. The study concluded that locally available feed ingredients can replace up to 100% of commercial feeds without negatively impacting the growth and survival of Nile tilapia. Among the tested diets, cowpea meal demonstrated the best growth performance. However, the slight decline in growth observed with the 100% replacement diets highlights the need for further research to enhance the nutritional quality of locally sourced feed ingredients. Such improvements could boost the efficiency of local feed resources and overall Nile tilapia production.

Growth differentiation factor 9 (GDF9) gene polymorphism and its association with litter size and some morphometric traits in local goats of Ethiopia

2025-06-02T12:18:17+00:00

Litter size is one of the major economically important reproductive traits in goat reproductive system. Identifying genes of major effect on litter size and utilizing them in breeding programs offers the opportunity to improve reproductive efficiency and profitability. Hence, the objective of the study was to identify growth differentiation factor 9 (GDF9) gene polymorphism and its association with litter size and morphometric traits in local goats. Blood samples and data on eight morphometric traits were collected from 150 does with different litter size (singleton, twin and triplet) at Dera district, North Shewa. All samples were genotyped using GDF9 gene primer pairs. Genetic polymorphism, population genetic indices and association analysis were done. The analysis of variance showed a significant variation (p<0.05) in morphometric traits among does with different litter size. The GDF9 locus showed two alleles (462, 478) and three genotypes (462/462, 462/478 and 478/478) that segregated with different frequencies. Only allele 462 was observed in does with singleton. However, both allele 462 and 478 were observed in does with twins and triplets with different frequencies (0.65 and 0.67). The closest genetic relationship was found between goats having twin and triplet (0.09), while does of singleton and their triplet counterparts were distantly apart (0.16). Significant (p<0.05) variation was observed among genotypes with different litter size and morphometric traits. However, further investigation with large sample size and different prolific goats’ population across different locations is required to substantiate the current result.

Microbiological and physicochemical analysis of Tej (Ethiopian honey wine) collected from Southwest Ethiopia

2025-06-02T12:21:46+00:00

Tej is a homemade fermented alcoholic beverage with tremendous social and economic importance in Ethiopia. However, there are issues associated with the safety, quality, and physicochemical properties of traditionally fermented Tej. Thus, this study was aimed to assess the microbial quality and the physicochemical properties of Tej collected from southwest Ethiopia. A total of 30 samples of Tej were collected from two regions, Oromia National Regional State (15 samples) and Southwest Ethiopia Peoples’ Region (15 samples). The microbiological and the physicochemical characteristics were analyzed by following standard analytical protocols. Microbial quality analysis revealed that lactic acid bacteria (6.8 ± 0.33 log cfu/mL) and yeast (6.7 ± 0.47 log cfu/mL) were the dominant microorganisms, with high significant differences (p = 0.001) in mean microbial count among the samples. On the other hand, the overall mean counts of aerobic mesophilic bacteria was (6.4 ± 1.30 log cfu/mL). However, molds, aerobic spore-forming bacteria and Enterobacteriaceae were not detected in all Tej samples. The mean physicochemical properties of Tej samples were recorded as follows: pH (3.6 ± 0.34), titratable acidity (0.19 ± 0.06 g/l00 mL), electrical conductivity (625 ± 152 μS/cm), specific gravity (0.73 ± 0.01), moisture content (96.70 ± 3.60 g/100 mL), and ash content (0.03 ± 0.05 g/100 mL). In conclusion, the microbial and physicochemical properties of Tej conducted in this study revealed the good keeping quality of the product, however further advanced investigations on microbial and chemical analyses, and use of starter cultures are recommended.