AN analysis of cow productivity of two commercial Friesian herds (namely Mashal and Kornbera in Gharbia and Giza Governo-rates, respectively), was carried out on 1646 lactation records. The Iwo herds belong to the General Cooperative of Developing the Animal Wealth and Products (GCDAWP), Data were collected in the period from 1981 to 1988 on yield of milk recorded in 90 days (90DY), 305 days (305DY) and total lactation yield (TY), lactation length (LP), dry period IPP), age at first calving (AFC), days open (DO) and calving interval (CI).
Averages of 90DY. 305DY. TY, LP, DP. AFC, _DO and CI were 1503 kg, 3838 kg, 4028 kg, 304 days, 69 days, 27.5 months, 100 days and 381 days, respectively. Herd effects were significant (P 0.05 or P < 0.01) for 305DY, TY, DP and DO, and non-signficant for 90DY, LP, AFC and CI. Cows of Ma.shal farm recorded higher 305DY and -rt, longer DP and shorter LP. DO and CI than those of kombera. Locally-born cows in Mashal farm had higher 90DY, TY, LP. DO and CI and shorter up than the imported ones, while im-ported cows in kornbera had higher 90DY and 305DY (and shorter UP, ap. Do and Cl) than locally-born cows. AFC of imported or 10- cally-born heifers was significantly affected (P < tun) by year and season of birth. As year of calving advanced milk yield increased (p