Joint genetic analysis for dairy cattle performance across countries in sub-Saharan Africa

This study assessed the feasibility of across-country genetic evaluation of dairy cattle in sub-Saharan Africa where data on livestock production is scarce. We estimated genetic parameters for 305-day milk yield in the first lactation and across five lactations, age at first calving and the interval between first and second calving, and calculated estimated breeding values of individual animals for these traits. Records from 2,333, 25,208 and 5,929 Holstein cows in Kenya, South Africa and Zimbabwe respectively, and 898 against 65,134 Jersey cows from Kenya and South Africa respectively were used in the analyses. Genetic gain from sire selection both within and across-countries was predicted. Genetic links between countries were determined from sires with daughters having records in two or more countries, and from common ancestral sires across seven generations on both the maternal and paternal side of the pedigree. Each country was treated as a different trait in the across-country evaluation. Results showed that genetic variance and heritability were not always estimable within-country but were significantly different from zero in the across country evaluation. In all three countries, there was greater genetic gain in all traits from an across-country genetic evaluation due to greater accuracy of selection compared to within-country. With the current data, Kenya stood to benefit most followed by Zimbabwe then South Africa from an across-country evaluation. Provided genetic links exist across countries, an across-country breeding programme using joint genetic evaluation is feasible and would provide a platform for accelerated genetic progress through selection and germplasm exchange between sub-Sahara African countries.