Abstract
A total of 4382 lactation records for 1868 Holstein cows sired by 182 bulls in a herd belongs to The Modern Agricultural Development Company (Dina). The data were analyzed using SAS (1998) and DF-REML (Meyer, 1998) for estimating the phenotypic and genetic parameters of some productive and reproductive traits. Means of total milk yield (TMY), 305-day milk yield (305-dMY), lactation period (LP), annualized milk yield (AMY), dry period (DP), days open (DO) and calving interval (CI) were 13172 kg, 10847 kg, 370 day, 10899 kg, 63.47 day, 154 day and 430 day, respectively. All the studied traits, except AMY, were significantly affected by parity of the cow. Also, year of calving showed a significant effect on all traits. Season of calving showed no significant effect on all traits except TMY and DP. Estimates of heritability ranged between 0.0003 for DP and CI to 0.13 for 305dMY. All estimates of the phenotypic and genetic correlation coefficients among these traits were positive. The results indicated that Holstein cattle in Egypt could produce high amount of milk if kept under reasonable management standards.
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