8TOLLA N,DEMEKES.Effect of calving year,season,age and parity classes on production and reproduction performance of Holstein-Friesian cows at Holetta state farm[J].Addis Ababa Ethiopia,2000(24/25):345-350.
9ASSEGED B,BIRHANU M.Survival analysis of calves and reproductive performance of cows in commercial dairy farms in and around Addis Ababa Ethiopia[J].Tropical Animal Health and Production,2004,36(7):663 -672.
10SHIFERAW Y,MERGA B,TESFU K.Reproductive disorders of crossbred dairy cows in the central highlands of Ethiopia and their effect on reproductive performance[J].Tropical Animal Health and Production,2005,37(5):427-441.
