الفهرس 
Effect of year of calvingOnly 14 pages are availabe for public view
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Abstract
Data for this study were obtained from the Friesian cattle herd, raised at Sakha Farm, located in the Northern Delta, Kafr El- Sheikh, Egypt. Data were collected over a period of 15 years from 1972 to 1986 and comprised 2700 normal lactation records from 1166 cows. The number of sires and number of daughters per sire were 139 and 7.73, respectively. The number of daughters per sire ranged from 2 to d7, all sires were random. For production, traits studied were maximum monthly milk yield (MMY), 305 day milk yield (305MY), total milk yield (TMY) and lactation period (LP); for lifetime production, total lifetime milk yield (MT) and total lactation period (TLP); for longevity, age at disposal (cull..age) and number of lactations completed (NLC), all weights were in kg and cull.’age was in months. Estimates of non genetic and genetic parameters of these traits were studied. Data were analysed using Mixed Model Least Squares analysis and Maximum Likelihood Computer Program (LSML, 1976) of Harvey (1977).