Oluyinka Abejide
University of Edinburgh, UK
Title: Joint genetic analysis of the performance of dairy cows in sub-Saharan Africa
Biography
Biography: Oluyinka Abejide
Abstract
The study was carried to evaluate if a joint across-country analysis may provide robust and accurate genetic parameters in cases where common sires have been used and hence, improve genetic progress. Data on Jersey cattle were obtained from the International Livestock Research Institute (ILRI), Kenya and from the Agricultural Research Council (ARC), South Africa. There were 31 sires from several foreign countries and 1 sire having daughters in both countries. Bivariate mixed linear model was fitted using ASReml. Country of performance was included in the model to account for the production system. Genetic parameters for individual (Kenya and South Africa) and joint evaluations (followed by standard errors) were estimated; Heritability (h2) of 305-day milk yield (MY) increased from 0.13 to 0.21 in individual and joint evaluations. h2 of age at first calving (AFC) increased from 0.15(0.05) to 0.58(0.05), h2 of calving interval (CI) ranged from 0.04(0.01) to 0.05(0.01), and repeatability of 305-day MY under the repeatability model increased from 0.13(0.10) to 0.43(0.01), Genetic correlation (rg) of 305-day MY and AFC was favorable from -0.53(0.24) to -0.15(0.09). However, CI and AFC for Kenya were non-estimable due to low number of records. Joint genetic evaluation increased the value of genetic parameter estimates as reflected in low standard errors than individual evaluation. This provides the potential for robust genetic parameter estimates and increased accuracy of selection especially where there are insufficient data from individual countries.