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75.CVM基因雜合型乳牛之夏季泌乳性能表現

吳明哲⁽¹⁾ 林德育⁽¹⁾ 黃鈺嘉⁽¹⁾ 蔡秀容⁽¹⁾ 張菊犁⁽¹⁾ 李素珍⁽¹⁾ 丁進來⁽²⁾

行政院農業委員會畜產試驗所⁽¹⁾  中華民國乳業協會⁽²⁾

脊椎畸形複合症（Complex Vertebral Malformation, CVM）基因型分為三型，正常型(TV)、雜合型(CV)及有病型(CVM)。有病型是一種致死遺傳，除了外觀上體型較小，可發現脊椎發育不全、脊椎變形、融合等各式各樣的病變，同時前肢及後肢腳趾骨明顯的向後翻轉彎曲，早產或是死產而造成酪農經濟損失，但雜合型是否會影響耐熱性與泌乳性能仍有待進一步研究。為瞭解CVM基因雜合型乳牛之夏季泌乳性能表現，檢測2008年17場參與中華民國乳業協會牧場，1756頭母牛，檢測結果除兩娟姍牛場，計120頭牛全為正常型外，共有186頭雜合型分佈於15個牧場，每場至少有兩頭以上的雜合型，比例為11.4%。由近5年DHI資料分析，雜合型305天體成熟乳量平均為8266kg與正常型8403kg差異不顯著。而雜合型夏季乳量平均為25.4與正常型25.6kg差異亦不顯著。但乳糖率正常型略高於雜合型(4.87% > 4.84%)，而雜合型之乳蛋質率與尿素氮則略高於正常型(3.32% > 3.28%, 11.3%>11.0%)，其餘的泌乳性能如總固型物、乳脂率、檸檬酸、體細胞數、蛋白質脂肪比，夏季產乳指數等，正常型與雜合型間差異均不顯著。整體而言，雖然CVM雜合型母牛夏季乳量略低，但差異很小，不需急於淘汰，但需留意公牛或精液的選擇，以逐步降低不良基因頻率。

關鍵語：脊椎畸形複合症、荷蘭牛、夏季

milk production PERFORMANCE of CVM GENE CARRIERS IN SUMMER

M.C. Wu⁽¹⁾, D.Y. Lin⁽¹⁾, Y.C. Huang⁽¹⁾, S.R. Tsai⁽¹⁾, C.L. Chang⁽¹⁾, S.J. Lee⁽¹⁾ and  J.L. Ding^{(2) (1)}Livestock Research Institute, Council of Agriculture  ⁽²⁾Dairy Association of ROC

Complex Vertebral Malformation, CVM, has three genotypes, normal(TV), carrier(CV) and defected(CVM).  CVM is a lethal genetic defect and refers to a combination of symptoms that include fused vertebrae, contracted joints in the front and rear legs, reduced body size and etc.  Major economic losses of CVM includes stillbirth and abortion.  But, the information of milk production performance of carrier was limited, especially in tropical summer.  From 17 dairy herds of dairy association, ROC, 1756 cows were genotyped for CVM in 2008.  Two herds, 120 cows, with all Jerseys are free of CVM.  There were 186 carriers, 11.4%, in 15 herds and each herd had at least 2 carriers.  By analysis of recent 5-year DHI data, 305-2X-ME and total milk of carrier(CV) and normal(TV) were 8266 kg vs. 8403 kg and 25.4 kg vs. 25.6 kg.  The differences were not significant.  Similar results were found for total solids, milk fat %, milk citric acid %, somatic cell counts, fat-protein ratio and Summer Milk Index(P>0.05).  Although, the milk protein and urea nitrogen % of carriers were slightly higher than normal cows’(3.32% >3.28%, 11.3% >11.0%), and lactose % was reverse, normal cow’s higher than carriers’(4.87% >4.84%).  In conclusion, the carrier cows produced near the same milk as normal cows in summer.  Culling carrier cows could not improve summer production efficiency.  The pace of culling carrier cows need not speed up.  But, farmer need be aware of bull or semen selection to reduce the defect gene frequency gradually.

Key words: Complex vertebral malformation, Holstein, Summer