불균등 착유 시간간격의 오전·오후 유량기록을 이용한 1일 산유량 추정에 관한 연구
A Study on Estimating Daily Yield from Morning or Afternoon Milking Records with Unequal Milking Intervals
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초록
오전(AM) 및 오후(PM)의 단일 착유기록에 의한 유우의 1일 생산량 추정을 위한 통계적 모형에 대한 연구를 실시하였다. 본 연구에서 조사한 모형들 가운데, Model 7은 각 요인 조합 구간별로 개별적인 회귀식을 추정함으로써 산차, 착유시간 간격, 비유 단계에 따른 이분산성을 고려할 수 있기 때문에 평균 오차 제곱합, 추정치와 실제 1일 유 생산량간의 상관계수 및 추정치의 분산을 고려할 때 가장 적합도가 높은 것으로 사료된다. 오후 착유 기록을 이용한 1일 유 생산량 추정치는 오전 착유 기록을 이용한 것보다는 정확도가 낮은 것을 나타났으며, Model 7의 경우 1일 유 생산량 추정을 위한 제반 요인이 추가되어 정확도가 높일 수 있으면서도 모형이 간단하기 때문에 적용이 간편한 장점이 있다.
Abstract
This study was conducted to evaluate the adequacy of an alternative a.m.-p.m. testing scheme for milk yield in comparison with the official test method based on weighing two milkings within 24 h. A total of 8,309 p.m. milking weights and 6,767 a.m. milking weights from 72 Holstein cows raised at N.L.R.I. were collected between October 2000 and November 2001. Seven statistical models were fitted to the data to derive formulas for estimating daily milk yields from morning or evening yields. In general, use of evening milkings less accurately estimated than did use morning milkings. Although the models do not differ much in the correlations between estimated and true daily milk yields, systematic under- and overestimation of daily milk yields were observed in all models with the exception of model 7, which accounted for heterogeneous variances by parity class, milking interval class, and lactation stage by fitting separate regression formulas within each combination of three factors.
참고문헌 (8)
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