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Akassa B.,Bako Agricultural Research Center | Belew D.,Jimma University | Debela A.,Jimma University
Journal of Agronomy

A study was conducted to determine the effect of inter and intra row spacing on potato (Solarium tuberosum L.) seed and ware tuber emergence and subsequent growth in 2011/12 production season. The experiment was laid out in a 6×3 factorial combination arranged in a randomized complete block design with three replications (Six levels of inter: 60, 65, 70, 75, 80 and 85 cm and three levels of intra row spacings: 20, 30 and 40 cm). Most of the variables collected in this experiment were significantly affected by inter, intra and/or their interactions except the number of main stem which did not show any change as the result to change of these treatments. Though most of the variables considered require wider spacing, it was observed that an indefinite increase in the space between plants and rows did not result to an increase in any of the variables apart from extending days to flowering and maturity. For the optimum emergence and successful growth of potato tubers for both seed and ware, spacing of 70-75 and 20-30 cm between plants and rows, respectively were identified as the best combination to be used in the study area. © 2014 Asian Network for Scientific Information. Source

Merera C.,Hawassa University | Merera C.,Bako Agricultural Research Center | Abebe G.,Ethiopia Sheep and Goat Productivity Improvement Program | Sebsibe A.,Ethiopian Meat and Dairy Technology Institute | Goetsch A.L.,Langston University
Journal of Applied Animal Research

Yearling sheep from Highland (Arsi-Bale, H) and Lowland (Black Head Ogaden, L) areas of Ethiopia were used to determine effects and interactions of animal origin, feeding and lengths of rest and feeding on harvest measures. Ten sheep of each origin were rested for 1, 2 or 3d after arrival at the abattoir and before slaughter with ad libitum availability of grass hay and water and an overnight fast preceding slaughter. Eighteen to 20 sheep of each origin were fed for 2, 4 or 6 weeks in length with ad libitum grass hay and a concentrate supplement at 220 g/day per animal. There was an interaction (P<0.05) between origin and the linear effect of feeding period length in average daily gain, with a much greater value for H-F2 compared with other treatments (209, 120, 125, 118, 90 and 113 g/day for H-F2, H-F4, H-F6, L-F2, L-F4 and L-F6, respectively). Hot carcass weight increased linearly with increasing length of rest (P<0.05), with a tendency (P<0.09) for greater change for H vs L animals and the effect (P<0.05) of feeding vs rest (8.09, 8.34, 8.73, 7.88, 8.19, 8.02, 9.08, 8.54, 9.13, 8.17, 8.03 and 8.57 kg for H-Rl, H-R2, H-R3, L-Rl, L-R2, L-R3, H-F2, H-F4, H-F6, L-F2, L-F4 and L-F6, respectively). Carcass pH or instrumental color did not change due to treatment. In conclusion, there is considerable opportunity to increase carcass weight of H by manipulating periods of rest after arrival at the abattoir and before slaughter longer than 1 day. Moreover, 2 weeks of feeding H sheep markedly increased carcass weight. © GSP, India. Source

Mirkena T.,International Livestock Research Institute ILRI | Mirkena T.,University of Natural Resources and Life Sciences, Vienna | Mirkena T.,Hawassa University | Duguma G.,International Livestock Research Institute ILRI | And 10 more authors.
Journal of Animal Breeding and Genetics

Based on the results of participatory approaches to define traits in the breeding objectives, four scenarios of ram selection and ram use were compared via deterministic modelling of breeding plans for community-based sheep breeding programmes in four diverse agro-ecological regions of Ethiopia. The regions (and production systems) were Afar (pastoral/agro-pastoral), Bonga and Horro (both mixed crop-livestock) and Menz (sheep-barley). The schemes or scenarios differed in terms of selection intensity and duration of ram use. The predicted genetic gains per year in yearling weight (kilograms) were comparable across the schemes but differed among the breeds and ranged from 0.399 to 0.440 in Afar, 0.813 to 0.894 in Bonga, 0.850 to 0.940 in Horro, and 0.616 to 0.699 in Menz. The genetic gains per year in number of lambs born per ewe bred ranged from 0.009 to 0.010 in both Bonga and Horro. The predicted genetic gain in the proportion of lambs weaned per ewe joined was nearly comparable in all breeds ranging from 0.008 to 0.011. The genetic gain per year in milk yield of Afar breed was in the order of 0.018 to 0.020kg, while the genetic gain per generation for greasy fleece weight (kg) ranged from 0.016 to 0.024 in Menz. Generally, strong selection and shorter duration of ram use for breeding were the preferred options. The expected genetic gains are satisfactory but largely rely on accurate and continuous pedigree and performance recording. © 2011 Blackwell Verlag GmbH. Source

Mirkena T.,International Livestock Research Institute ILRI | Mirkena T.,University of Natural Resources and Life Sciences, Vienna | Mirkena T.,Hawassa University | Duguma G.,International Livestock Research Institute ILRI | And 7 more authors.
Livestock Science

This review summarizes available information on genetics of adaptation in major livestock species focusing on small ruminants. Adaptation to humans and consequences of domestication on predator aversion, mechanisms of adaptation to available feed and water resources, severe climates and genetic evidence of disease tolerance or resistance have been presented. The latter focuses on gastrointestinal parasites and bacterial diseases. The resource allocation by the animal to production and fitness traits under both optimal and sub-optimal conditions has a genetic background. Such information would help in identifying the most appropriate and adapted genotypes capable of coping with the environmental challenges posed by the production systems or, wherever possible, in adapting the environments to the requirements of the animals. © 2010 Elsevier B.V. Source

Worku M.,Bako Agricultural Research Center | Banziger M.,International Maize and Wheat Improvement Center | Schulte auf'm Erley G.,Leibniz University of Hanover | Friesen D.,CIMMYT Ethiopia | And 2 more authors.
Field Crops Research

Development of more nitrogen (N) efficient maize (Zea mays L.) varieties capable of producing higher maize grain yields under conditions of low soil N supply could improve the livelihoods of smallholder subsistence farmers in sub-Saharan Africa who cultivate infertile soils and are unable to purchase fertilizer inputs due to lack of access or cash constraints. A previous study found that increased grain yield under N stress was associated with higher post-anthesis N uptake, grain production per unit N accumulation and N harvest index. This study examines the underlying physiological mechanisms as well as root morphological differences as they affect N efficiency.Sixteen hybrids with contrasting N-efficiency were evaluated under a range of soil N fertility levels at Harare, Zimbabwe, in 2003 and 2004 and Kiboko, Kenya, in 2003 for grain yield, harvest index, ears per plant, kernel number per ear, kernel weight, kernels per row, kernel row number and grain carbon/nitrogen (C/N) ratio as well as anthesis-silking interval and indicators of photosynthetic efficiency during grain filling. Differences in root-system size (estimated by root electrical capacitance), root density and distribution (estimated by coring), and soil mineral N depletion were assessed between contrasting hybrids.There was considerable genetic variability in yield components and dry matter partitioning among the hybrids under all N conditions and a strong relationship between N efficiency and dry matter partitioning. Significant hybrid-by-environment interactions indicated that increasing harvest index under high-N conditions may not increase harvest index under low-N conditions. The N-efficient hybrids were characterized by a lower anthesis-silking interval, higher dry matter production during grain filling, higher kernel number and relatively higher grain C/N ratio under limited N supply compared with inefficient hybrids. These hybrids were also associated with stay-green characteristics in that they maintained more green leaves, and had lower leaf senescence and higher leaf chlorophyll content during and after flowering. This may imply a higher photoassimilate supply in the N-efficient hybrids during and after flowering under low-N conditions.Between two contrasting hybrids, an N-efficient hybrid had greater root-length density in, and depleted more mineral-N from the surface soil layer than an N-inefficient hybrid. Although there was significant variation between hybrids, total root-system size was not significantly related to N efficiency indicating that selection for improved performance under low-N did not increase total root-system size in tropical maize. Although this study found a relationship between root-length density, soil mineral N depletion and plant N efficiency, the effects were not sufficiently compelling to conclude that they are causative factors. © 2012 Elsevier B.V. Source

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