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This study was conducted to investigate the lactation and dry period durations, real and 305 days milk yields, milk fat and protein levels and somatic cell counts of Holstein-Friesian cattle in five randomly chosen private farms in England which have a developed cattle management policy. Also the effects of the individual farm environments on the above traits have been observed.
The material of the study was the yield records of the Holstein-Friesian cattle between the years 1993-2004. During the study 1847 records were investigated for the dry period durations, 2514 records were examined for lactation period durations, real and 305 days milk yields, milk fat and protein and somatic cell counts. For the statistical analysis of the milk production traits the Duncan-test was used.
The investigated milk yield traits of lactation and dry period durations, real and 305 days milk yields, milk fat and protein rates and milk somatic cell counts were 324.32 days. 67.18 days, 7715.23 kg, 7218.62 kg, 4.03%, 3.33% and 138.00 ('000 cells/ml), respectively.
Effects of environmental factors such as the individual farm environments, lactation number, year and season on the yields were examined in the study. Lactation and dry period duration, real and 305 days milk yield, milk fat and protein rates and somatic cell counts were affected by the farm environment and yielding year significantly (P<0.01). where as season had an insignificant effect on the real milk yield and the somatic cell count whilst the lactation turn had an insignificant effect on the dry period duration. These two factors (season and lactation turn) had significant effects on other traits (P<0.01 and P<0.001).
The results of this study have shown that the cattle breeding farms can obtain high level yields by providing optimal conditions to the animals. Management conditions and high quality breeders have enabled the farms to reach higher yields every passing year.