الفهرس 
Introductionيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Data used in this study were obtained from milk record of Holestein Friesian herd kept at dalla farm which far from Cairo city by 130 km. data were collected during the period from 1987 to 1996. A total of 3758 normal lactation records of cows producing for at least 150days were used. Number of sires, cows within sires and daughters per sire were 345, 1292 and 10.60 respectively. Genetic analysis included sires with at least 10 daughters were used. Traits studied were cumulative monthly milk yield (CMY)and 305 days milk yield.
The results obtained from the analysis of data could be summarized as follows:
1-least squares means for 30 d My ,60 d My,90 d My, 120 d My, 150 d My, d180 d My, 21 d My, 240 d My, 270 d My and 305 d My were 518, 1155, 1774, 2340,3881, 3354, 3745,4105,4362 and 4544 kg, respectively.
2-month of calving had a significant effect on CMY and 305 d My expect for 30 d My. In addition, winter and spring calvers had the highest CMY and 305 d MY.
3-year of calving had a significant effect on different traits studied.
4-parity had a significant effect on CMY and 305 d My.
The present results show that CMY and 305 V reached maximum in the third lactation.
5- Sire and cow within sire had a significant effect on CMY and 305 d My.