荷蘭牛擠乳效能與產乳性能相關標記基因探討

乳牛群擠乳效能與產乳性能顯著影響乳牛場生產效率，結合相關標記基因輔助選拔，可有效降低乳牛群非自願性淘汰率與提升選拔效益。本研究旨在建立擠乳效能相關基因，催產素/運載蛋白I基因 (OXT) 與含splA/ryanodine受體結構域之細胞因子信號傳導抑制因子盒1基因 (SPSB1)，多態性位點鑑定平台，並綜合評估該兩基因與四個已知產乳相關基因 (CXCR1、LEP、CSN3 與DGAT1)之影響。應用MS-PCR法建立OXT基因型鑑定平台與PCR-RFLP法建立SPSB1基因型鑑定平台。產乳效能資料來自台灣花蓮泌乳牛群圓盤式搾乳機智慧管理系統擠乳紀錄 (包括乳量與擠乳時間) 與該場乳牛群改良 (DHI) 性能資料，並採集369 頭泌乳牛血液，進行DNA萃取與基因型鑑定。運用 SAS 9.4 進行分析，擠乳效能之統計模式包括上述六個基因之基因型、產次、擠乳時段（早晨與晚間）、泌乳階段 (DIMs)，以及產次與DIMs交感為固定效應，殘差為逢機效應。DHI性能資料分析模式，除擠乳時段外，餘與擠乳效能分析之統計模式者同。結果顯示，OXT-TT與SPSB1-GG型泌乳牛具有顯著較高單次擠乳量與305天校正脂肪量、較快下乳速率、較短總下乳時間與較低體細胞分數。同時，SPSB1-GG型泌乳牛之305天校正乳量與乳蛋白質率也較高，CXCR1-CC與LEP-CT型者具顯著較高單次擠乳量、較快下乳速率及較短總下乳時間；但前述兩基因多態性對產乳性狀影響不顯著。CSN3-AA型泌乳牛具顯著較高單次擠乳量、305天校正乳量與下乳速率，惟乳蛋白質率則以CSN3-BB型者顯著較高。此外，具DGAT1基因之A等位基因泌乳牛具顯著較高單次擠乳量與下乳速率；但305天校正脂肪量與乳脂肪率，則以DGAT1-KK型者顯著較高。綜合評估本研究探討之各基因多態性對泌乳牛擠乳效能與產乳性狀之影響，建議經非遺傳影響因素 (如產次與飼養管理等環境效應) 校正後，更新用種乳牛 CXCR1-LEP-CSN3-OXT-DGAT1-SPSB1基因之有利組合基因型為CC-CT-AA-TT-AA-GG。

關鍵字

乳牛；擠乳效能；產乳性能；單核苷酸多態性

並列摘要

Improving milkability and milk production of dairy herds that significantly affect production efficiency, combined with marker-assisted selection, can effectively reduce the involuntary culling and thus improve selection efficiency. The aims of this study were to identify polymorphic sites and setup genotyping platform of milking efficacy related maker genes, oxytocin-neurophysin I gene (OXT) and splA/ryanodine receptor domain and SOCS box containing 1 gene (SPSB1), and further comprehensively to evaluate the impact of the two genes and four known milking-related genes (CXCR1, LEP, CSN3, and DGAT1) on milkability and milk production. The polymerase chain reaction-restriction fragment length polymorphism and mutagenically separated polymerase chain reaction techniques were used to establish the genotyping platform with genotype identification. Milking traits evaluated included milkability data and DHI records of a commercial dairy cattle farm in Hualien, Taiwan. Milkability data (single milking yield and time) originated from the smart dairy managing system of rotary milking parlour used in the farm. A total of 369 lactating cows was blood sampled for DNA extraction and genotyping. The data was analyzed using SAS version 9.4 (SAS Institute Inc. 2008). In addition to random residual, the statistical model for milkability traits included the genotypes six genes studied, parity, milking period (morning and evening), days in lactation (DIMs), and parity*DIMs interaction as fixed effects. Also, the same model was employed for the DHI performance data analysis, except milking period excluded from the model. Results showed that cattle with OXT-TT and SPSB1-GG genotypes had more single milking yield (SMY) and 305-2X-ME fat yield, faster milking speed (MS), shorter total milking time (TMT), and lower somatic cell scores. Furthermore, SPSB1-GG genotype cattle showed significantly higher 305-2X-ME milk yield and milk protein percentage. Also, CXCR1-CC and LEP-CT genotypes cattle are favored in term of higher SMY, faster MS, and shorter TMT. But CXCR1 and LEP gene polymorphisms were not related with milk production of dairy cattle. Although CSN3-AA genotype cattle showed significantly higher SMY, 305-2X-ME milk yield, and MS, CSN3-BB genotype cow had higher milk protein percentage. In addition, cow with DGAT1-A allele showed significantly higher SMY and MS, but DGAT1-KK genotype cattle produced higher 305-2X-ME fat yield and milk fat percentage. In conclusion, after non-genetic factors adjustments, cattle with CC-CT-AA-TT-AA-GG genotype combination for CXCR1-LEP-CSN3-OXT-DGAT1-SPSB1 genes would be favorable for milking efficiency promotion in dairy breeding program.

並列關鍵字

Dairy cattle ； Milkability ； Milk production ； Single nucleotide polymorphism

參考文獻

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