الفهرس 
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Abstract
The data were collected over a period of ten years (from 1985 to 1994) from two farms belonging to the Egyptian company for Meat and Milk production, Ministry of Agriculture, Egypt. The First farm (Fariskur) city and the another farm was Showha farm, which is situated at the North Part of Nile Delta, about 8 km south of Mansoura city. Live body weights of 1110 Friesian calves (650 male and 460 Female) progeny of 22 sires were used in the present study. The traits in this study were birth weight, weaning weight and different ages during 12 months and daily gains during the period from birth until 12 month, all weight and daily weight gain were in Kg. Factors which affected on these traits were year of birth and season of calving, farm, sex of calf as fixed effects and sire effect as random effect. Overall means of birth weight, weight at three, six, nine and twelve months of age were 30, 79, 122, 165 and 204 Kg, respectively. The average daily gain were 0.556, 0.521, 0.498, 0.468 and 0.502 kg/day during the period from birth to three months of age, 3 to 6, 6 to 9, 9 to12 and from birth to twelve months of age. Heritability estimates of birth weight, weight at 3, 6, 9 and 12 months of age were 0.122, 0.188, 0.095, 0.165 and 0.184, respectively. Sire effect on different daily weight gain during different studied periods showed highly significant effect, except during the period from 36 months of age. Heritability estimates of daily weight gain from birth to three months of age, 3 to 6, 6 to 9, 9 to12 were 0.190, 0.031, 0.073 and 0.182, respectively. The range of ETA`s for daily weight gain from birth to three months of age, from 3to 6, from 6 to 9, from 9 to 12 and from birth to 12 months of age were 0.0590, 0.0173, 0.0455, 0.0713 and 0.444 kg/day, respectively. The percentage of number of sires that had positive estimates of ETA?s for different traits studied were ranged from 37.5 to 54%. All Spearman rank correlation coefficients among ETA?s of studied traits were strong and positive The present results indicated that the variation to definable environmental effects must be removed use of suitable adjustment factors to estimate accurate genetic parameters. The economic importance must be given to growth traits breeding programs to improve the growth performance of bull and heifer calves. Great variation was observed in growth traits indicated that genetic change can be made by selection for these traits to improve the growth rate in Friesian claves under Egyptian condition