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[en] The performance records of Sanga and Friesian-Sanga crossbred cows kept at the artificial insemination (AI) Centre of the Amrahia dairy farm in the Accra plains of Ghana between the period January 1998 to December 2007 were evaluated. The intervals from calving to first AI, calving to conception, and calving interval were prolonged especially in the Sanga cows inseminated with Friesian semen, aver- aging 158.8 ± 8.9, 177.5 ± 9.5 and 517.9 ± 13.5 d respectively. In Friesian-Sanga cows bred with Friesian semen these intervals were respectively 115.7 ± 19.2, 138.7 ± 16.3 and 510.3 ± 41.0 d. These parameters were not affected (P > 0.05) by season of calving preceding AI and season of insemination. The conception rates at first AI service and for all inseminations were low in the Sanga (42.6% and 46.0% respectively) and in crossbred cows (53.5% and 53.4% respectively). They were not affected (P > 0.05) by the season of insemination. Improving the nutritional status of the cows through strategic supplementation coupled with effective heat detection techniques, appropriate timing of AI, as well as efficient methods of storage, transport and handling of semen should improve the reproductive performance of cows. (author)
[en] This paper presents a seismic hazard map for the southern part of Ghana prepared using the probabilistic approach, and seismic hazard assessment results for six cities. The seismic hazard map was prepared for 10% probability of exceedance for peak ground acceleration in 50 years. The input parameters used for the computations of hazard were obtained using data from a catalogue that was compiled and homogenised to moment magnitude (Mw). The catalogue covered a period of over a century (1615–2009). The hazard assessment is based on the Poisson model for earthquake occurrence, and hence, dependent events were identified and removed from the catalogue. The following attenuation relations were adopted and used in this study—Allen (for south and eastern Australia), Silva et al. (for Central and eastern North America), Campbell and Bozorgnia (for worldwide active-shallow-crust regions) and Chiou and Youngs (for worldwide active-shallow-crust regions). Logic-tree formalism was used to account for possible uncertainties associated with the attenuation relationships. OpenQuake software package was used for the hazard calculation. The highest level of seismic hazard is found in the Accra and Tema seismic zones, with estimated peak ground acceleration close to 0.2 g. The level of the seismic hazard in the southern part of Ghana diminishes with distance away from the Accra/Tema region to a value of 0.05 g at a distance of about 140 km.