Zymogram patterns of α-amylase isozymes inEthiopian tetraploid wheat landraces: insight into their evolutionaryhistory and evidence for gene flow

The variation for -amylaseisozymes was analyzed in 71 tetraploid wheat (AABB genome)landraces from Ethiopia, including accessions of Triticumdicoccon Shrank, T.turgidum L., T.durum Desf., T.pyramidale Percival and T.aethiopicum Jakubz., by thin-layerpolyacrylamide gel isoelectric focusing. Four zymogram phenotypeswere obtained from all the materials studied. Except inT. dicoccon, however, thestandard pattern of the durum wheat variety, LD222, was predominant.T. dicoccon showed twozymogram types that differed for the absence or consistently weakactivity of band 18(-Amy-B1)of the malt type. Band 1(-Amy-B3)of the malt type was fixed in T.dicoccon and present in only 10% of thefree-threshing (FT) types. Generally, the resultsindicated that the variation for-amylase isozymes in cultivatedtetraploid wheats, including landraces from secondary centers, is lowpossibly due to the founder effect or as a result of selection. Thedata were useful for inferences about the evolutionary history ofEthiopian wheat landraces. It is speculated thatT. dicoccon was the firstwheat to arrive in the Ethiopian highlands ca.5000 years ago. However, it is not known whether the present day FTEthiopian tetraploid wheat landraces are direct descendants ofT. dicoccon, or whetherthey were introduced independently. The clear differences in-amylase zymogram patterns favor the latterhypothesis. However, the presence of band1 in some of the FT types indicated the occurrence of geneflow between the FT types and T.dicoccon, which may also explain thequantitative nature of spike threshability in these landraces.Possible implications for durum wheat breeding arediscussed.     

Cropping sequence and nitrogen fertilizer effects on the productivity and quality of malting barley and soil fertility in the Ethiopian highlands

The productivity and quality of malting barley were evaluated using factorial combinations of four preceding crops (faba bean, field pea, rapeseed, and barley) as main plots and four nitrogen fertilizer rates (0, 18, 36, and 54 kg N ha^?1) as sub-plots with three replications at two sites on Nitisols of the Ethiopian highlands in 2010 and 2011 cropping seasons. Preceding crops other than barley and N fertilizer significantly improved yield and quality of malting barley. The highest grain yield, kernel plumpness, protein content, and sieve test were obtained for malting barley grown after faba bean, followed by rapeseed and field pea. Nitrogen fertilizer significantly increased yield, protein content, and sieve test of malting barley. All protein contents were within the acceptable range for malting quality. Inclusion of legumes in the rotation also improved soil fertility through increases in soil carbon and nitrogen content. We conclude that to maximize yield and quality of malting barley, it is critical to consider the preceding crop and soil nitrogen status. Use of appropriate break crops may substitute or reduce the amount of mineral N fertilizer required for the production of malting barley at least for one season without affecting its quality.     

Prevalence, bacterial causes, and antimicrobial susceptibility profile of mastitis isolates from cows in large-scale dairy farms of Northern Ethiopia

The study was undertaken to determine the prevalence of bovine mastitis, isolate mastitis causing bacteria, assess the association of some risk factors, and determine the antibiotic resistance pattern of bacterial isolates in cows in large-scale dairy farms of Northern Ethiopia. A total of 305 lactating and nonlactating cows were included in the present study. The overall prevalence of clinical and subclinical mastitis was 3.6 and 33.8?%, respectively. The quarter level prevalence was 15.4?%; from which, 11.9 and 1.1?% were subclinical form and blind teat, respectively, while the remaining 2.4?% were of clinical form. Staphylococcus aureus accounted for 36?% of the isolates followed by Escherichia coli (27.3?%). Risk factors including age (p?9?years (OR?=?3.63, 95?% CI?=?1.42-9.25)), cows with four to seven calves (OR?=?3.39, 95?% CI?=?2.06-5.60), and cows in late lactation stage (OR?=?3.79, 95?% CI?=?1.64-8.75). In multivariable logistic regression analysis, age (p?=?0.005) and lactation stage (p?=?0.027) showed statistically significant association with the occurrence of mastitis. The antimicrobial susceptibility pattern showed high susceptibility of S. aureus to nalidixic acid (82.4?%) followed by chloramphenicol (58.8?%); however, these species were resistant to the rest of the antimicrobials tested. Highest resistance was observed against clindamycin and ampicillin. Coliform bacteria (E. coli and Klebsiella pneumoniae) showed resistance to most of the antimicrobials used. Detailed investigation is needed to identify the interplay of managemental and environmental risk factors to design appropriate control measures.     

Estimation of genetic parameters for growth traits and Kleiber ratios in Boer x Central Highland goat

Tropical Animal Health and Production - Accurate performance evaluation and genetic parameters estimation are the prerequisites for any successful genetic improvement program. This study was...