Livestock are a cornerstone of rural livelihoods and economic development in many low-income countries, yet their productivity remains low. Improving livestock performance requires coordinated interventions in genetics, health, and nutrition supported by skilled professionals, modern technologies, and strong institutional infrastructure. In this context, North–South and South–South collaborations are essential for strengthening research capacity and implementing effective breeding strategies. Therefore, the KOEF 03/2020 project aims to build genomic research capacity by training Ethiopian experts in animal breeding, with a focus on quantifying heterosis and inbreeding depression in African dairy cattle. Implemented by Mekelle University (Ethiopia), BOKU University (Austria), and the International Livestock Research Institute (ILRI) in Ethiopia and Kenya, the project also fosters institutional partnerships and promotes South-South and North-South collaboration.

To achieve these goals, the project facilitated multiple international exchanges focusing data analysis, sample collection, and consultations with local institutions engaged in dairy improvement. The core research investigated breed differences and heterosis effects in crossbred Ethiopian dairy cows, using milk yield (a productivity trait) and calving interval (a fitness trait) as key indicators.A total of 4,759 phenotype records and genotype data of dairy cows with 38,344SNP were obtained from the African Dairy Genetic Gains (ADGG) project in Ethiopia. Local ancestry information was calculated using Efficient Local Ancestry Inference (ELAI) software, employing reference populations comprising Local cattle (Fogera (37) and Boran (44)) and international breeds (Jersey (37) and Holstein Friesian (29)).  The prediction of heterosis effects was performed by calculating the additive, dominance, and epistasis levels from ancestry informative markers. A Mixed linear model was fitted in ASReml-R.

Heritabilites of 0.18 and 0.003 were estimated for milk yield and calving interval, respectively. Significant breed differences were observed for milk yield and calving interval, with values of 8.11 kg and-38.16 days, respectively, indicating that the milk yield of pure international dairy cows is more than double that of local Ethiopian cows and calving interval is more than one month shorter for international dairy cows. No significant dominance and epistatic effects were identified, indicating that F1 or F2 cows will be intermediate in performance compared to ancestral pure breeds. These results are not supported by a recent meta-study that found strong heterosis effects for milk production and many functional traits in similar types of crosses under tropical conditions. Therefore, further analysis is needed.