Hormonal oestrus synchronization in four sheep breeds in Ethiopia: Impacts on genetic improvement and flock productivity - Gizaw, Solomon; Tesfay, Y.; Mekasha, Yoseph; Mekuriaw, Z.; Gugsa, T.; Ebro, A.; Gebremedhin, Berhanu; Hoekstra, Dirk; Tegegne, Azage (International Livestock Research Institute, 2016)