الفهرس 
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Abstract
Data of present study were collected from a commercial dairy herd situated in Cairo-Alexandria desert road and named Alexandria-Copenhagen Company far from Alexandria by about 76 km. Data of productive and reproductive records of Holstein Friesian cows were obtained and represented the period from 1998 to 2010. The total number of lactation records was 3464 of 1060 dairy cows which were sired by 99 sires and of 691 dams. The main objectives of this work were:5. To investigate the effects of non-genetic factors on calving interval and its components (days in milk or lactation length, days open and dry period) of Friesian cattle in Egypt.6. To investigate the effects of age at first calving on productive traits this includes (total milk yield, 305-days milk yield and peak milk yield) and days open.7. To investigate the effects of level of milk production of cow on calving interval, days open and dry period.8 To estimate genetic parameters which include (heritability, genetic correlation, phenotypic correlation and breeding value), for the previously mentioned reproductive and productive traits.This study revealed the following main outcomes: Effect of age of cow, parity and lactation length was highly significant on calving interval (CI). CI increased with advancement of age, it was 361.69 day for cows 2-3 years,