Published in Scientific Papers. Series D. Animal Science, Vol. LXI, Issue 1
Written by Muhittin TUTKUN, Sadık Metin YENER
This study was carried out to estimate the trend components (the phenotypic, genetic and environmental trends) for 305-day milk yield in Holstein Friesian Cattle raised between the years 1989-2012 at the Ceylanpınar State Dairy Farm. In order to estimate the trend components 6165 lactation records of 2055 Holstein cows was analysed. It was found that the lactation period average was 313.23 ± 28.47 days, the annual average lactation milk yield was 6197.88 ± 1681.35 kg and adjusted 305-day lactation milk yield was found to be 6164.41 ± 1713.90 kg. In order to estimate of genetic parameters, standardized milk yield according to 305-day lactation period (lactation 1, 2 and 3) were analysed primarily with repeated-measured animal models by using MTDFREML programs. According to the data obtained in the study, the lactation length, average lactation milk yield and average 305-days milk yield adjusted were calculated as 313.23 ± 28.47 days, 6197.88 ± 1681.35 kg and 6164.41 ± 1713.90 kg, respectively. The phenotypic, environmental and genetic trends for 305-days milk yield were found to be -70.72 kg/year, -70.53 kg/year and -0.19 kg/year, respectively.
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