PHENOTYPIC AND GENETIC PARAMETERS OF MILK PRODUCTION AND REPRODUCTIVE PERFORMANCE OF HOLSTEIN CATTLE UNDER THE INTENSIVE PRODUCTION SYSTEM IN EGYPT

Cow productivity in Holstein-Friesian cattle was analyzed in fourteen commercial private herds.All herds belong to members of the General Cooperative for Developing Animal Wealth and Products, Egypt.A total number of 4120 lactation records for 1085 cows sired by 290 bulls were used.The records covered the period from 1999 to 2003.Traits studied were 305 day milk yield (305d MY), total milk yield (TMY), lactation period (LP), dry period (DP), age at first calving (AFC) and calving interval (CI).Data were analyzed by Multiple Trait Derivative Free Restricted Maximum Likelihood (MTDFREML) procedure using repeatability multiple trait Animal Model analysis.Means of 305d MY, TMY, LP, DP, AFC and CI were 9038 kg, 12054 kg, 407 days, 63.6 days, 29.2 months and 470 days, respectively.Heritability estimates for the same traits were 0.27, 0.22, 0.07, 0.05, 0.23 and 0.05, respectively.Also, repeatability and phenotypic and genetic correlations between traits were estimated.The results indicated that raising high yielding Holsteins in commercial farms in Egypt is technically feasible.Additive genetic variance showed large contribution to total variation in milk yield traits indicating possibility of improving these traits by genetic selection.Selection based on first lactation could be used satisfactorily to improve milk yield traits.