الفهرس 
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Abstract
The present work was aimed to study the reproductive performances of imported Holstein Frisian heifers to Egypt in pregnant heifers state. The environmental influences including climate, season, feeding and management on the reproductive performances of imported pregnant heifers before and after parturition till next conception were recorded. This study was aimed to record the different reproductive parameters, and monitoring them with relation to different environmental conditions so that to enhance the improvement of reproductive performance was improved and suppress other environmental conditions that reduce the reproductive performance.
This study was carried out on 393 Holstein Frisian Heifers, all imported from Germany with average age 30 months, and pregnancy duration vary from 4 to 9 months. The animals belong to Sanad farm for animal and agriculture production.
The heifers was divided in to two main groups:
• group A: Heifers subdivided according to nature of parturition in relation to season:
A1: Heifers calved normally in summer season.
A2: Heifers calved normally in winter season.
A3: Heifers suffered dystocia in summer season.
A4: Heifers suffered dystocia in winter season.
A5: Heifers suffered abortion in summer season.
A6: Heifers suffered abortion in winter season.