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This study was conducted to investigate the reproductive traits 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 1993-2003. During the study 720 records were examined for reproductive traits, 1847 records were investigated for the calving interval and open periods. For the statistical analysis of the rational reproductive traits the t-test have been employed Duncan-test was used for other yields and contrast-test for corrected mean values of Effect ratios.
The pregnancy, barren, normal birth, abort, still-birth and twin rates were respectively 97.08%, 2.92%, 95.56%, 0.97%, 0.56% and 0.56%. The first calving age of the cows was 26.20 months, the calving to first service interval was 77.35 days, number of inseminations for a pregnancy was 1.64, the calving interval was 389.00 days and open period was 112.07 days.
Effects of environmental factors such as the individual farm environments, parity, year and season on the yields were examined in the study. Rational reproductive traits such as pregnancy, barren, normal birth, twin or still births and abort rates were observed to be affected by the individual farm environments significantly (P<0.05), the season factor was significantly important (P<0.05) on barren and normal birth rates and insignificant on the other traits (P>0.05). All the factors were significantly effective on the first calving age (P<0.001) as well as the calving to first service interval, whereas it was insignificant for the service number (P>0.05). The effect of year and season on the calving interval and the open period was significantly important (P<0.01), however, the farm and parity effect was insignificant (P>0.05).
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.