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Data used in this investigation were collected from 4370 records relevant to 874 purebred Friesian cows which belong to Shobratana Animal Production Society, located in the north part of Delta region near Tanta city in Egypt. These cows were daughters of 43 sires. The records used covered the period from 1985 to 2003. The following six productive and reproductive traits of the first lactation were analyzed: Total Milk Yield (TMY, kg), dry period (DP, day), lactation length (LL, day), days open (DO, day), calving interval, (CI, month) and age at first calving (AFC, month).sire random effect and month and year fixed effect. Data were analyzed using Linear Mixed Model Least Squares and Maximum Likelihood (LSMLMW) computer program of Harvey (1990). The overall means of TMY, DP and LL were 5387 kg, 72.9 days and 327 days, respectively. The overall means of CI, DO and AFC were 13.4 month, 121 days and 27.8 month, respectively. Heritability estimates for TMY, DP, LL, CI, DO and AFC were 0.141±0.074, 0.109±0.069, 0.040±0.057, 0.104±0.068, 0.202±0.084 and 0.217±0.087 respectively. The ranges of breeding values of all sires in the pedigree for TMY, DP, LL, DO and CI were 685 kg, 18 day, 8.15 day, 48.2 day and 1.05 month, respectively. Spearman rank correlations and Pearson correlations among estimated breeding values of all sires in pedigree provided by the genetic analysis ranged between -0.712 to 0.907. The objectives of the present study were: 1) to estimate some genetic and non-genetic factors affecting productive and reproductive traits, 2) to estimate genetic and phenotypic parameters for these traits and 3) to estimate breeding values for sire Friesian cows in this farm. Rank correlations of animals between traits were the lowest for reproduction traits. It could be concluded that improving the environmental conditions will improve these traits.

Having a successful heifer raising operation is not only relevant financially, but also influential for the future of the dairy herds. Milk feeding has a significant role on the health and growth of calves before weaning, in addition to the direct progressive effects on future performance post-weaning. Therefore, the aim of this study was to compare the effects of constants amount of milk (CMS) versus step-up/step-down (SUSD) on calf performance in two different suckling schedules of suckling milk gradually till 9th weeks of calf age, then decreasing it till weaning. For this study, forty Holstein heifers calves utilized between birth and 8 months of age were randomly divided into four groups of 10 calves each. Grouping was performed according to suckling protocol (constant versus variable) and suckling schedule (2 versus 3 times/day). Each calf suckled 600 kg of milk in a suckling period of 120 days. Body weight (BW), in addition to five body measurements: chest girth (CG), height at wither (HW), height at rump (HR), body length (BL), and diagonal length (DL), were recorded weekly. The heaviest BW was observed on SUSD calves suckling twice/day which had also the highest HW at weaning. Similarly, were BW, HW, and CG at 6 months of age. Also, the same group achieved the largest daily BW (0.902 kg/day), BL (0.246 cm), and CG (0.338 cm/day) gains during the pre-weaning phase. However, CMS suckled 3 times/day calves had the largest daily BW gain between birth and 6 or 8 months of age. CMS twice/day calves had the largest daily gain in CG from weaning to 6 months and from weaning to 8 months of age followed by SUSD suckling 3 times/day calves. Also, CMS twice/day calves had the largest daily gain in rump height from birth to 8 months of age compared to other groups. It can be concluded that when equal amounts of milk were fed during the suckling period, suckling protocol affected growth rate before weaning but that effect diminished as calf age increased after weaning.

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