台灣荷蘭牛泌乳性狀之重複勢估計

自乳牛群性能及經營效率改良計畫所建立之資料庫中，擷取牛隻分娩日期介於1996年1月至2007年12月間完成乳量性能檢定之泌乳牛泌乳性狀紀錄，計有584場酪農戶、1,957頭公牛及其後裔女兒牛共74,095筆紀錄，以VCE5變方成分估計軟體之限制性最大似然法（Restricted Maximum Likelihood, REML）計算泌乳性狀之重複勢。結果顯示，乳生產性狀之全期乳量、全期脂量、全期蛋白質量與全期乳糖量等性狀之重複勢估值（repeatability ± SE）分別為0.55±0.05、0.43±0.06、0.40±0.05與0.38±0.04；乳成分性狀之乳脂率、乳蛋白質率、乳糖率、無脂固形物率與總固形物率者分別為0.47±0.06、0.43±0.05、0.29±0.05、0.31±0.05與0.35±0.06；代表乳品質性狀之體細胞分數者則為0.57±0.05。乳生產性狀之永久環境變方比例介於0.04至0.23間，以全期乳量者（0.23）最高，乳成分性狀者介於0.13至0.22間，以乳蛋白質率者（0.22）最高，而體細胞分數者則為0.44。體細胞分數之重複勢在所有泌乳性狀中為最高者，顯示各胎次間之體細胞分數表現存在強烈之相關性，由於體細胞數與乳房健康性狀間有較強之遺傳相關，此表示初產牛具高體細胞者，後續泌乳期發生乳房炎趨勢可能較高。乳牛泌乳性狀重複勢之估值可作為乳牛遺傳評估之重要參數，亦可提供酪農進行牛隻淘汰管理之參考。

關鍵字

台灣荷蘭牛；泌乳性狀；變方成分估計；重複勢

並列摘要

There were 74,095 daughter cow's milking records retrieved through the Dairy Herd Improvement (DHI) database in Taiwan from January 1996 to December 2007. All milking records have been assigned to 584 Herds and 1,957 sires, respectively. The repeatability, of lactation traits applied for dairy cows in Taiwan, has been estimated under the method of Restricted Maximum Likelihood (REML) with VCE5 package. The repeatability for milk yield, fat yield, protein yield, lactose yield, fat%, protein%, lactose%, solid non fat%, total solid% and somatic count score (SCS) were 0.55 ± 0.05, 0.43 ± 0.06, 0.40 ± 0.05, 0.38 ± 0.04, 0.47 ± 0.06, 0.43 ± 0.05, 0.29 ± 0.05, 0.31 ± 0.05, 0.35 ± 0.06 and 0.57 ± 0.05, respectively. The ranges of permanent environmental variance fraction were from 0.04 to 0.23 for milk production traits, 0.13 to 0.22 for milk composition traits and 0.44 for SCS. The SCS had the highest repeatability among lactation traits therefore there was a stronger correlation existed among different lactations. The higher repeatability of SCS means that if a dairy cow has higher SCS in primiparous stage, it would be with higher possibility of suffering from mastitis in the later lactation. The repeatability of lactation traits for Taiwan Holsteins was not only as a critical estimate using in genetic evaluation, but also as an important reference in culling management of dairy cows.

並列關鍵字

Taiwan Holsteins ； Lactation traits ； Variance component estimation ； Repeatability

主題瀏覽