Genetic divergence in two tropical maize composites after four cycles of reciprocal recurrent selection          下载免费PDF全文

Adesike O. Kolawole  Abebe Menkir  Melaku Gedil  Essie Blay  Kwadwo Ofori  Jennifer G. Kling 《Plant Breeding》2017,136(1):41-49

Two tropical maize composites were subjected to four cycles of reciprocal recurrent selection to develop divergent inbred lines with good combining ability. This study was conducted to examine the extent of genetic diversity, changes in allele composition and genetic structure, of 100 randomly selected S₁ lines each from the original (C₀) and advanced (C₄) selection cycles of TZL COMP3 and TZL COMP4, genotyped using single nucleotide polymorphism (SNP) markers. Results revealed that the proportion of alleles at both low and high frequencies decreased from C₀ to C₄, whereas those at intermediate frequencies increased at C₄ in the two composites. More unique and other alleles were lost at C₄ in TZL COMP3 relative to those in TZL COMP4. The changes in different measures of genetic diversity were either small or negligible with selection in the two composites. The proportion of markers departing from Hardy–Weinberg equilibrium (HWE) decreased with selection, whereas the total number of pairs of markers in linkage disequilibrium increased with selection in the two composites. Examination of changes in population structures using a model‐based approach as well as cluster and multivariate analyses found a high degree of concordance in stratifying the 400 S₁ lines into four non‐overlapping groups corresponding to the two selection cycles each within the reciprocal composites. The observed molecular‐based divergence between cycles within the same composite and the clear differentiation between the complementary composites highlight the importance of reciprocal recurrent selection for preserving genetic diversity for long‐term selection. This increases the potential of the advanced selection cycles to sustain genetic gain in productivity of hybrids adapted to the savannas in West and Central Africa.  相似文献   

Genetic diversity and population structure analysis of Grass pea (Lathyrus sativus L.) accessions collected from North-Western Ethiopia using SSR markers     

Mekonen  Desalegn Abebe  Abraham  Adane  Oselebe  Happiness  Afiukwa  Celestine  Ilesanmi  Oluyinka  Abebe  Tiegist Dejene 《Genetic Resources and Crop Evolution》2022,69(3):1247-1260

Genetic Resources and Crop Evolution - Grass pea (Lathyrus sativus L.) is a legume crop known to be an excellent source of protein, tolerant to drought, waterlogging, and salinity. The crop is used...  相似文献   

Suramin sensitivity of stocks ofTrypanosoma evansi isolated in the Sudan     

G. Abebe  T. W. Jones  R. Boid 《Tropical animal health and production》1983,15(3):151-152

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Effects of dietary protein concentration on the response of growing chicks to methionine.     

T R Morris  R M Gous  S Abebe 《British poultry science》1992,33(4):795-803

1. Experiments were conducted independently at two stations to measure the requirement for methionine in chick diets with crude protein (CP) varying in 8 steps from 140 to 280 g/kg diet (experiment 1) or from 90 to 300 g/kg (experiment 2). 2. Protein composition was the same at all protein concentrations within a trial. The diet was designed to be first-limiting in methionine and DL-methionine was added to provide 5 ratios of methionine to CP at each protein concentration. 3. Methionine required for maximum growth rate or maximum efficiency of food utilisation was estimated at each protein concentration by fitting a quadratic regression equation to the relevant data. The requirement was also estimated by fitting the Reading model to data for growth rate and methionine intake. 4. In both trials and by all three methods of estimation, the methionine requirement (g/kg diet) for maximum performance increased as a linear function of dietary CP concentration and nearly in direct proportion to CP. 5. It is concluded that diets which contain surplus protein, beyond that needed to maximise growth rate or food efficiency, need supplementation with methionine beyond that required when dietary protein is just adequate. A suitable rule for practical formulation is that methionine concentration in chick diets should be not less than 0.025 times the dietary CP concentration.  相似文献   

Pastoralists’ perceptions of feed scarcity and livestock poisoning in southern rangelands, Ethiopia     

Abebe A  Eik LO  Holand Ø  Adnøy T  Tolera A 《Tropical animal health and production》2012,44(1):149-157

A survey was conducted between April and July 2007 to generate information on dry season feeding management and livestock poisoning in the southern rangelands of Ethiopia. A total of 119 pastoralists were interviewed using a semi-structured questionnaire. Moreover, additional information was obtained through informal discussions. The study revealed that pastoralists have rich knowledge of natural resource management and utilization and employ various strategies such as migration, collection of grasses and pods, and cutting branches to overcome feed scarcity during dry/drought periods. Migration of livestock and people to areas with better grazing is the widely used strategy. However, the implementation of this strategy is diminishing as a result of changes such as bush encroachment, expansion of settlements, and crop cultivation in dry-season grazing lands. The respondents also indicated the presence of poisonous plants in the rangeland, and about 20 such plants were identified by the respondents. Various species and classes of livestock are reported to be affected by toxic plants particularly in the dry and early rainy seasons when feed is in short supply. A more extensive survey is required to document all poisonous plants in the rangelands and to identify the major toxic principles in the different species. Future development interventions should consider the prevailing constraints and potentials of the rangelands with active participation of the pastoralists.  相似文献   

Evaluation of three non‐genetically modified soybean cultivars as ingredients and a yeast‐based additive as a supplement in practical diets for Pacific white shrimp Litopenaeus vannamei          下载免费PDF全文

X. Qiu  A. Buentello  R. Shannon  A. Mustafa  A. Abebe  D.A. Davis 《Aquaculture Nutrition》2018,24(1):173-183

Two growth trials and a physiology assessment were conducted to evaluate three non‐genetically modified (GM) soybean cultivars as ingredients in practical diets for Pacific white shrimp, Litopenaeus vannamei. In addition, a commercially available fermented yeast product was evaluated as dietary supplement. For the growth trials (46 and 35 days, respectively, for trials 1 and 2), the basal diet was primarily composed of soybean meal (SBM), fishmeal (FM), whole wheat, corn protein concentrate, poultry meal (PM, pet food grade) and corn starch. Non‐GM cultivars were processed with novel methodologies to produce Navita? ingredients (N1, N2 and N3) which were incorporated at low (L) or high (H) levels into the experimental diets, in partial replacement of FM and full replacement of conventional SBM. The last two formulations incorporated the fermented yeast for a total of nine experimental diets (Table 1 ). Results from the growth trials indicate that shrimp fed diet 5 (HN2) exhibited significantly lower (p < .05) weight gain as compared to shrimp fed diets 1 and 2 (basal and LN1, respectively) in trial 1, as well as compared to animals fed diets 1, 2, 3 and 8 (basal, LN1, HN1 and basal + yeast) in trial 2. The feed conversion ratio significantly increased for shrimp fed diet 5, in contrast with shrimp fed diets 1, 2, 3 and 8 in trials 1 and 2, as well as compared to shrimp fed diets diet 6 (LN3) in trial 2. For the physiological assessment (stress and immune responses), only the effects of diets 1, 3, 8 and 9 (basal, HN1, basal + yeast and HN1 + yeast, respectively) were investigated. Granular cell counts were significantly higher for shrimp fed the yeast‐containing diets. Haemolymph glucose and haemolymph packed cell volume were significantly reduced for shrimp fed diets 3, 8 and 9. No significant differences were observed in total haemocyte counts, hyaline cells counts, semi‐granular cells counts, haemolymph protein, haemocyte phagocytic capacity and haemocyte respiratory burst activity. Results of this work indicate that selective soy breeding technology coupled with novel processing options has the potential to increase the nutritional value of conventional SBM for shrimp feeds. Trends on immune responses were more difficult to elucidate possibly due to the limited length of the feeding trial.  相似文献   

Comparative performance of top-cross maize hybrids under managed drought stress and variable rainfed environments     

Abebe Menkir  José Crossa  Silvestro Meseka  Bunmi Bossey  Shehu G. Ado  Kwadwo Obengantiwi  Chabi G. Yallou  NTji Coulibaly  Gbadebo Olaoye  Haruna Alidu 《Euphytica》2016,212(3):455-472

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Hydatidosis of slaughtered cattle in Wolaita Sodo Abattoir,southern Ethiopia     

Kebede N  Mekonnen H  Wossene A  Tilahun G 《Tropical animal health and production》2009,41(4):629-633

The study was carried out from July 2007 to June 2008 in Wolaita Sodo Abattoir to assess the status of hydatidosis in cattle. Routine meat inspection, hydatid cyst count and characterization were conducted. Out of 400 cattle slaughtered in Wolaita Sodo Abattoir 64 (16%) animals were found harboring hydatid cysts. Thorough meat inspection in the abattoir revealed that 74 visceral organ were found harboring one or more hydatid cysts. The infection of the lung, liver, spleen and kidney were found to be 45.94% 45.94%, 6.75% and 1.35% respectively. From the total of 283 hydatid cysts counted 153(54.06%), 17(6.00%), 5(1.76%), 108(38.16%) were found to be small, medium, large and calcified cysts respectively and 170(60.28%), 5(1.76%) and 108(38.16%) were sterile, fertile and calcified cysts respectively. The rate of cyst calcification was higher in the liver than in the lung while fertility rate was higher among the cysts of the lung. Hydatid cyst viability rate of 40% was observed.  相似文献   

Genotype X environment interaction in two breeds of chickens kept under two management systems in Southern Ethiopia     

Fassill Bekele  Hans Magnus Gjøen  Jessica Kathle  Tormod Ådnøy  Girma Abebe 《Tropical animal health and production》2009,41(7):1101-1114

Rhode Island Red (RIR) and Fayoumi chickens were evaluated on-station in a college farm and on-farm in village farms, whereas local chickens were only tested under on-farm condition. Traits recorded are egg production and egg quality, body weight and feed efficiency at 4, 8 and 12 months of age. Significant age effect was found for most traits except for shell thickness, albumen height and egg length. Also, significant breed by management system interactions were found for all traits measured in both systems. Fayoumi chickens were higher in egg production in both management systems. Moreover, they were higher than RIR in feed efficiency. RIR were higher in most egg quality traits and had higher weight gain. Local chickens performed below the two exotic breeds in most of the traits, but had higher weight gain than Fayoumi. Chickens kept on-farm had poorer performance than those kept on-station in all traits except for yolk colour.  相似文献   

Potato Breeding for Nitrogen-Use Efficiency: Constraints,Achievements, and Future Prospects     

Baye Berihun Getahun 《Journal of Crop Science and Biotechnology》2018,21(3):269-281

In this review, the genetic potential and efforts made on different aspects of potato breeding for nitrogen-use efficiency (NUE) and the possible physiological and genetic mechanisms determining NUE in potato in relation to other model crops are presented. Strategies to utilize the diverse gene pool of potato and improve the NUE in contrasting N environments are currently evaluated under field conditions using different selection approaches. So far, focused efforts have been made on the identification of potato genotypic differences which will allow for the analysis of specific components of nitrogen-use efficiency and the effect of nitrogen fertilizer on a range of physiological processes and morphological traits of potato. To my knowledge, despite the availability of genome sequence and QTLs identified for NUE and related agronomic and physiological traits in potato, and genomic information from other model crops, candidate genes on NUE have not yet been identified in potato. To maximize the success rate of potato breeding for NUE, basic knowledge how plants respond to different N regimes and other environmental conditions and use of DNA marker technology are vital.  相似文献