Estimation of Variance Component and Environment Effects on Somatic Cell Scores by Parity in Dairy Cattle

젖소집단의 산차에 따른 체세포점수의 환경효과 및 분산성분 추정

  • 조광현 (축산연구소) ;
  • 나승환 (축산연구소) ;
  • 서강석 (축산연구소) ;
  • 김시동 (축산연구소) ;
  • 박병호 (축산연구소) ;
  • 이영창 (축산연구소) ;
  • 박종대 (축산연구소) ;
  • 손삼규 (축산연구소) ;
  • 최재관 (축산연구소)
  • Published : 2006.02.28


This study utilized test day of somatic cell score data of dairy cattle from 2000 to 2004. The number of data used were 124,635 of first parity, 134,308 of second parity, 77,862 of third parity, 41,787 of forth parity and 37,412 of fifth parity. The data was analyzed by least square mean method using GLM to estimate the effects of calving year, age, lactation stage, parity and season on somatic cell score. Variance component estimation using test day model was determined by using expectation maximization algorithm- restricted maximum likelihood (EM-REML) analysis method. In each parity, somatic cell score was low for younger group and was relatively high in older groups. Likewise, for lactation stage, the score was low in early-lactation and high in late-lactation in first parity and second parity. Nevertheless, for the third, fourth and fifth parity, however, high somatic cell score was observed in mid-lactation. Generally, the score was high in the peak. Although in fourth and fifth parity, the score was low in late-lactation. Environmental effect of season, somatic cell score was generally low from September to November for all parities. The score was high between June and August when the milk production is usually low. The heritability in each parity were 0.05, 0.09, 0.10, 0.05 and 0.05 for parity 1, 2, 3, 4, 5, respectively. Genetic variance value was estimated to be high in second, third and fifth parity in early-lactation and to be low in first and forth parity.


Variance component;Somatic cell score;EM-REML;Environmental effect


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