305일 산유량 추정을 위한 보정계수(補正係數)의 개발에 관한 연구 = A Study on the Development of Correction Factors to Estimate 305-day Milk Yield

국문 초록 (Abstract)

本 硏究에서는 305日 産乳量을 推定하기 위한 補正係數를 算出하고 그 正確度를 알아보기 위해 경기, 강원, 충청, 경북지역의 38개 牧場에서 蒐集한 記錄中 1,710個의 記錄을 産次別로 2個群(1産, 2産以上) 分娩月別로 3個群(12月∼5月, 6月∼8月, 9月∼11月)으로 나누어 分析하였으며 그 結果는 다음과 같다.
1. 305日 補正係數의 算出時 모든 回歸式의 R²은 0.96∼0.99로 높게 나타났다.
2. 305日 實際産乳量과 本 硏究의 補正係數로 推定한 乳量의 相關係數는 0.96이고 平均間 有意差는 나타나지 않았다.
3. USDA 補正係數로 推定한 乳量은 實際産乳量보다 過小推定되었으며 平均間 有意差를 나타냈다(P<0.01).
4. 總乳量과 月檢定乳量과의 相關係數는 6번째 月檢定乳量이 r=0.8775로 가장 높게 나타났으며 大體로 4번째부터 6번째까지가 r=0.8689∼0.8775로 높게 나타났다.
5. 各 月檢定乳量間의 相關關係를 보면 隣接한 月檢定乳量間의 相關係數가 r=0.75∼0.84로 높게 나타났다.
6. 總乳量에 대한 累積乳量의 相關係數는 連續 5回의 月檢定乳量의 累積에서 r=0.93으로 높게 나타났고 回를 거듭할수록 1에 가까와졌다.
7. 産次別로는 2産以上이 1産보다 夏節期 分娩時 乳量의 減少가 많은 것으로 나타났다.

다국어 초록 (Multilingual Abstract)

A total of 1710 lactation records obtained from Holstein cows raised at 38 ranches in Kyong-Gi, Kang-Won, Chung-Chong, and Kyong-Puk were analyzed to calculate 305-day correction factors and to test the accuracy of the factors.
Records were classified into 2 parity groups (1 and 2-7 parites) and 3 calving month groups (Dec.- May, June-Aug. and Sept.-Nov.).
The results obtained in this study are summarized as follows:
1. The R² values of regression equations to calculate 305-day correction factors were high (R² = 0.96-0.99).
2. Correlation coefficient between the actual 305-day yield and the estimated yield by 305-day correction factors in this study was high (r = 0.96) and there was no significant difference.
3. The estimated 305-day milk yield by USDA factors was underestimated than the actual 305-day milk yield and there was high significant difference between the two yields (p < 0.01).
4. The correlation between total yield and monthly test yield was the highest 6th month (r = 0.88) and the R² values appeared to be the high in 4th, 5th, 6th months (r = 0.87-0.88).
5. Correlation coefficients between adjacent monthly test productions was higher than others (r = 0.75-0.84).
6. Using the cumulative monthly test records to calcualte correction factors, the cumulative productions over the 5 months were available (r = 0.93-0.99).
7. The milk yields of cows were more severely affected by summer calving than the first lactating heifers.