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37.乳牛群乳量及乳質的年度改進速率

李世昌　吳明哲　黃鈺嘉　張菊犁 李素珍 曾青雲 陳志毅

 行政院農業委員會畜產試驗所

乳牛群參加乳量乳質檢測有助於提昇牧場經營效率。應用www.angrin.tlri.gov.tw網路資訊化以來，自2001至2005年間平均每戶每月有65、70、73、74、70頭泌乳牛參加乳測。每頭每日產乳量從2001年的21.46kg(176819頭次/287戶)、增為2002年的21.77kg(220193頭次/315戶)、2003年的22.02kg(243053頭次/348戶)、2004年的22.17kg(248822頭次/345戶)、2005年的22.73kg(169359頭次/319戶，僅1至9月)，這五年來，每頭日產乳量平均已增加3.31%，年度改進速率有0.83%。具有22kg以上的高乳量戶數上，該戶總乳中每毫升體細胞數少於30萬個的戶數自2001年的35戶(116高乳量戶的30.1%)，增加至2002年的41戶(136戶的30.1%)、2003年的63戶(161戶的39.1%)、2004年的79戶(164戶的48.1%)、2005年的77戶(178戶的43.2%)，乳量及乳質並重的戶數增加2.2倍(77戶/35戶)。當以上述乳量及乳質並重的戶來看，日產乳量在2001至2005年分別有24.15+1.68、24.58+1.75、24.41+1.73、24.41+1.81、24.87+2.24kg；體細胞數分別為21.05+4.09、21.92+3.88、21.02+4.00、20.54+3.80、19.67+5.40萬個/mL；固形物含量有12.28+0.36、12.38+0.26、12.39+0.26、12.45+0.29、12.47+0.28%；乳蛋白質與脂肪比(P/F ratio)有0.89+0.07、0.88+0.06、0.87+0.05、0.87+0.06、0.89+0.05。乳質的體細胞數減少量及固形物含量增加率在五年來，年度改進速率分別有1.63%及0.38%。再依每戶年度最高的日產乳量分析，2001至2005年最高日乳量平均分別有46.57+5.25、47.26+5.37、47.63+5.00、46.92+4.85、47.36+5.68kg，暗示乳量及乳質並重的牛隻泌乳高峰在47kg。在2005年的乳量及乳質並重的77戶優質戶，其乳脂肪含量平均為3.73+0.23%、蛋白質含量平均為3.24+0.07%及乳糖含量平均為4.80+0.05%。在2005年優質戶中的許慶良牧場有最高日產乳量有31.79kg、體細胞數為16.89萬個/mL、固形物含量有12.60%。根據上述測乳資訊，牛群的乳量及乳質可逐年同步改進。

關鍵語：乳牛、乳量、乳質

ANNUAL INCREASE OF MILK YIELD AND QUALITY OF COWS

S. C. Lee, M. C. Wu, Y. C. Huang, C. L. Chang, S. J. Lee, C. Y. Tseng and J. Y. Chen

Livestock Research Institute, Council of Agriculture, Executive Yuan

Production efficiency of dairy farm is achieved by participating test of milk quality. Application of web information of www.angrin.tlri.gov.tw for analysis of milk yield and quality, an average of number of cows per farm was 65, 70, 73, 74, and 70 head from 2001 to 2005, respectively. Daily milk yield per cow form 2001 to 2005 were 21.46 (176819 milk samples collected from 287 farms), 21.77 (220193, 315), 22.02 (243053, 348), 22.17 (248822, 345), 22.73 kg (169359, 319, only from Jan to Sept of 2005). For the last five years, an increase of 3.31% on daily milk yield was obtained with the annual increase rate of 0.83%. Elite farms having mean daily milk yield grater than 22 kg and with less than 30 x104/mL of milk were selected, there were 35 farms (30.1% of 116 high production farms having greater than 22 kg of daily milk yield) in 2001, and there were 41 farms (30.1% of 136 farms), 63 farms (39.1% of 161 farms), 79 farms (48.1% of 164 farms), and 77 farms (43.2% of 178 farms) from 2002 to 2005. Number of elite farms increased 2.2 times (77 farms/35 farms) form 2001 to 2005. Milk yield and quality from those of elite farms were averaged by milking year, daily milk yield were 24.15+1.68, 24.58+1.75, 24.41+1.73, 24.41+1.81, 24.87+2.24kg from 2001 to 2005, respectively; somatic cell counts were 21.05+4.09, 21.92+3.88, 21.02+4.00, 20.54+3.80, 19.67+5.40 x104/mL; total solid content were 12.28+0.36, 12.38+0.26, 12.39+0.26, 12.45+0.29, 12.47+0.28%; protein to fat ratio (P/F ratio) were 0.89+0.07, 0.88+0.06, 0.87+0.05, 0.87+0.06, 0.89+0.05. Annual decrease amount on somatic cell counts was 1.63% and annual increase percentage of total solid content was 0.38% for the last five years. Analysis on data of the highest daily milk yield of the year for each farm, year mean of the highest daily milk yield were 46.57+5.25, 47.26+5.37, 47.63+5.00, 46.92+4.85, 47.36+5.68kg from 2001 to 2005, respectively. It indicated that the yield peak of lactation curve was 47 kg from those cows in the elite farms. Among those of 77 elite farms in 2005, milk fat content averaged 3.73+0.23% and with 3.24+0.07% of milk protein content and 4.80+0.05% of milk lactose. In 2005, the greatest amount of daily milk yield was 31.79 kg from Hsu Farm with 16.89 x104 cells/mL and 12.60% of total solid content in milk quality. According the above results, both milk yield and quality for milking cows were improved annually.

Key Words: Dairy cows, Milk yield, Milk quality