J Jo ou ur rn na al l o of f E En nv vi ir ro on nm me en nt ta al l a an nd d O Oc cc cu up pa at ti io on na al l S Sc ci ie en nc ce e Abstract A survey based experiment was conducted from November 2010 to April 2011 in 196 households to assess egg handling and qualities of scavenging chickens reared in highland, midland and lowland agro-ecological zones of Amhara Regional State, Ethiopia. For egg quality determination, among 196 households, 30 of them who keep only local chickens were identified from each agro-ecology from which 588 eggs (196 eggs from each agro-ecology) were collected. The flock size in highland, midland and lowland agro-ecologies was 8.5, 7.4 and 8.4 chickens, respectively. The results indicated that about 95% and 70% of the respondents fumigate day old chicks with smoke and clip tail feathers, respectively. The average age at first egg lay was 6.94, 6.43 and 6.57 months for highland, midland and lowland agro-ecologies, respectively. The survivability of chickens in highland, midland and lowland agro-ecological zones was 55.0%, 61.4% and 55.1%, respectively. On the average 79.1% hatchability, 58.3% chick survivability was found in the study area. The observed values of egg weight, egg length, egg width, yolk height, albumen height and Haugh unit were significantly (p< 0.05) different between the investigated agro-ecologies. Accordingly, all these traits were (p< 0.05) higher in midland than those of highland and lowland agro-ecological zones. Agro-ecology did not affect shape index, shell thickness, yolk width and yolk index values. The respective average egg weight, shell thickness and shape index values were 39.6 g, 0.296 mm and 73.2%. The average values of yolk height, yolk width and Haugh unit were 16.1 mm, 36.8 mm and 73.2, respectively. In conclusion, the midland agro-ecological system appears to favor the survivability and expression of external and internal egg quality traits of scavenging rural chickens.

The food and feeding habits of Clarias gariepinus (Burchell, 1822) were studied in Lake Koka, Ethiopia, in May 2011 (dry month) and September 2011 (wet month). Three hundred and thirty eight nonempty stomach samples were analysed using frequency of occurrence and volumetric methods of analysis. Detritus, insects, macrophytes, zooplankton and fish were the dominant food categories by occurrence, and they occurred in 79.6%, 63.6%, 63.0%, 56.2% and 15.4% of the stomachs, respectively. Volumetrically, the above food items comprised 24.3%, 14.1%, 14.5%, 19.3% and 21.8% of the total volume of food categories. Phytoplankton and gastropods were of low importance, and they occurred in 28.7% and 8.6% of the stomachs, respectively. Their volumetric contributions were 3.2% and 2.8% of the total volume of food categories. During the dry month, fish, zooplankton, insects and detritus were important food categories, while during the wet month detritus, macrophytes, insects and gastropods were important. Smaller catfish diets were dominated by detritus, macrophytes and insects, whereas larger catfish shifted to fish and zooplankton. Based on the results, C. gariepinus was found to be omnivorous in its feeding habits in Lake Koka.

Growing trends in industrialization in Ethiopia have raised concerns about pollution of water bodies particularly of lakes. This study was therefore conducted to 1) characterize the chemical contents of major industrial effluents (namely textile ceramic and soft drink factories) that reached Lake Hawassa and 2) investigate the effects of the above mentioned factory effluents on survival of larvae fish and growth of algae. Effluent samples were collected from the outlet lagoons of each factory in December, 2009. Then, effluent samples were analyzed for total N, NO3-N, NH4-N, S 2− , − 2 4 SO , − 3 4 PO , COD, total dissolved solids (TDS) and heavy metals at the federal Environmental Protection Agency (EPA) Laboratory, Addis Ababa. The experiments on the impact of effluents on survival of fish larvae and growth of algae were conducted using six concrete paved ponds (with different concentration of effluent). The results of chemical analysis showed that textile effluent had high COD (nearly 3 times higher), TDS (19 times higher) as well as − 3 4 PO (39 times higher) than the maximum permissible limits (MPL) set by Environmental Protection Authority (EPA). Among heavy metals, Zn and Fe of textile effluent were much higher (41 and 1.5 times higher, respectively) than the MPL set by EPA. Ceramic effluent also contained high concentration of − 3 4 PO (24.5 times), S 2− , − 2 4 SO (2 times) and Zn (14 times) exceeding the limit of EPA. Regarding soft drink factory, high values of COD, − 3 4 PO and Zn were found in the effluent than the limit specified * Corresponding author. B. Berehanu et al. 793by EPA. The biological treatment lagoons of the respective source were not effective since the effluents were taken from the last treatment lagoon (outlet lagoon) and some of the measured parameters were higher than MPL. Results of the pond experiment showed that 5%, 10% and 20% concentration levels of the HTF effluent killed significantly high proportion of the fry (65%, 86.8% and 88.7%, respectively). In contrast, fry mortality in ceramic and soft drink effluent treatments, even at 10 and 20% concentration levels, stayed nearly below 10%, which were not far off from the mortality of the control groups. Algal biomass in the treated ponds varied with the type of effluent treatment and concentration level. Compared with the first day, chlorophyll "a" concentration measured on the 7 th day had increased by 51%, 48%, 74%, 27% and 31% at 0%, 1%, 5%, 10% and 20% concentrations, respectively of textile effluent. The 5% treatment level of textile effluent caused the highest rate of algal growth above the growth rate observed in the control pond, but further increased in concentration to 10% and 20% resulted in a lower growth of algae than in the control pond. Therefore, textile effluent may boost up algae growth at lower concentrations (~5%) but at higher concentration levels its toxic effect may become inhibitory. Regarding the effluent of soft drink factory, algal growth progressively diminished with increasing concentration of the...

The objectives of this study were to understand the production potential, challenges and opportunities in Hawassa. A total of 132 randomly selected milk producing households (HH's) were interviewed. Dairy cattle in Hawassa city were mainly reared for commercial milk production. 87.5, 79.8 and 60% of large, medium and small size dairy farms, respectively, produced cow milk for sale. The main feed items available in Hawassa city are crop residues, including stover, grass hay, industrial by-products and to some extent Attela-a by-product of a local alcoholic beverage. Deep wells, tap water and rarely, the Lake Hawassa and accessible rivers are drinking water sources for their animals. The average daily milk yield at household level was estimated to be 13.3, 51.5 and 81.4 liters (L) HH-1 for the small, medium and large size farms, respectively with an average being 20.31 L HH-1. Shortage of animal feeds (26%) is the most important limiting factor of dairy production followed by limited space (23%), and animal disease incidence (18%). Therefore, empowering the urban dairy producers by addressing the hampering problems, are helpful to improve production and increase the income of the producers as well as to fulfill the wide range of dairy product demand in the urban areas.

The sustainability of a given fishery is a function of the number of sexually matured fish present in water. If there is intensive immature fishing, the population of fish reaching the stage of recruitment will decrease, which in turn results in lower yield and biomass. The present study was conducted to estimate the extent of immature fish harvesting by the commercial fishery of Lake Hawassa. Random samples of 962 Oreochromis niloticus and 672 Clarias gariepinus were taken from the fishermen's catch for two weeks from May 15 to 30, 2011, which was peak spawning season for both fish species. The maturity of the sampled fish was determined by visual examination of developmental stages of gonads based on their size, structure and the space they occupy in the body cavity of fish. Lengths at first sexual maturity of male and female C.gariepinus were55.9cm and 54.8cm, respectively and that of male and female O.niloticus were 20.8cm and 20.3cm, respectively. There was heavy immature fishing of C.gariepinus as high as 77.6% but immature fish harvesting was slight for O.niloticus (23.0%). Thus immature fishing of C.gariepinus should be stopped as soon as possible since only one fifth of the population has the chance to breed and replenish the stock before it is caught. Widening the currently used mesh size from 8cm to 10cm is recommended to avoid immature fishing.