Records of 5662 normal lactations produced by 1029 cows were analyzed by a single-trait Animal Model to estimate transmitting abilities of cows and their dams and sires for some lactation traits of Holstein cattle raised in El-Salhia commercial farm in Egypt Lactation traits stucled were 90-day milk yield (M90), 305-day milk yield (M305), total milk yield (-ROY) and length of lactation period (LP). Repeatability estimates were moderate or slightly high (0.388. 0.402 and 0.417) for M90. M305 and IMY. respectively and low (0.146) for LP. Transmitting abiiities (TA) were estimated for cows (CTA) using their own records, along with those for their dams (DTA) and sires (STA) without using their own records. Ranges rn estimates of CIA for M90. M305, TMY and LP were 321 kg, 1087 kg, 1388 kg and 121 days, respectively. The corresponding ranges were 182 kg, 600 kg, 801 kg and 6.7 days for DTA and 208 kg, 702 kg, 851 kg and 8.5 days for STA. The percentages of cows and their dams and sires that had positive transmitting abilities for M90, M305, TMY and LP were 47.9, 47 3, 47.5 and 54.3% for CTA. 46.3, 46.4, 45.7 and 53.3% for DTA and 50.4, 52.5, 50.4 and 51.8% for STA. Ft could be concluded that selecting cows according to CIA would be more efficient than selecting them according to STA or DTA.
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