臺灣黑豬屠體性狀與體型及遺傳變異相關之分析

Abstract

臺灣於 2002 年加入世界貿易組織（World Trade Organization, WTO），使得國產豬肉面臨強大的市場壓力。臺灣黑豬可以提供作為具本土特色之品牌豬肉來源，但是民間的黑豬生產系統由於無政府的輔導，致使目前臺灣黑豬生產之遺傳育種、生長資料、飼養管理及營養需求等資料大都付之闕如；黑豬在肉品市場的標價方式以活體決價為主，並參照白毛肉豬的議價標準，但是白毛肉豬是以瘦肉率為訴求，與黑豬的肌內脂肪（intramuscular fat, IMF）的訴求相異，造成黑毛豬得不到肉質區隔的優勢，且黑毛豬飼養豬業者得不到應有的經濟效益。本研究針對民間黑豬養豬場進行調查，藉由體型、屠體性狀及遺傳變異等資料的收集與分析，以作為未來建立臺灣黑豬最適配種政策及屠體評級的參考資料。 本試驗收集自 7 個不同的養豬場收集了共 250 頭臺灣黑豬的資料，包括屠前體型測量值（活體重、體高、胸深、胸寬、臀寬、胸圍、體長及前管圍）、屠體性狀（屠體重、屠體長第 1 肋、最後肋及最後腰椎三點與此三點之平均背脂厚度）、第 9~10 肋間腰眼肌肉化學組成（水分、粗蛋白質及肌內脂肪含量）及抽取基因組 DNA 以 PCR-RFLP技術來分析臺灣黑豬的遺傳多態性（心臟型脂肪酸結合蛋白基因、肌肉調控因子基因—— myogenin 與 myf6及鈣離子釋放通道基因）。 試驗結果顯示，來自 7 個不同養豬場的臺灣黑豬在屠宰體重有顯著性差異（P<0.05），屠宰體重最重的是來自 Farm 1（147.37±1.38 kg），最輕的是來自 Farm 7（102.61±2.57 kg），顯示臺灣黑豬之最適屠宰體重尚無標準可依，故後續之統計分析均以屠宰體重 120 kg進行矯正。根據豬隻屠宰前進行體型測量及外觀觀察，可將臺灣黑豬分成 3 種體型：精肉型、醃肉型及肥肉型，並以此 3 種體型分組，結果顯示不同體型的豬隻在胸深、胸寬、胸圍、前管圍、屠體長、背脂厚度及肌肉內脂肪含量有顯著差異（P<0.05），未來可進一步利用胸深、胸寬、胸圍及前管圍等體型測量項目訂定適用於臺灣黑豬之體型評分指數，以及作為屠體評級的參考項目。 在本次採樣的臺灣黑豬族群中，並未發現心臟型脂肪酸結合蛋白基因、myogenin、myf6的 AvaI 切位及鈣離子釋放通道基因的不同型別在體型、屠體性狀及肌肉化學組成等有顯著差異（P>0.05），但是 myf6 的 BseRI 切位的不同基因型在體長、臀寬、前管圍、粗蛋白質含量、肌肉內脂肪含量及背脂厚度等有顯著差異（P<0.05）。 為了解本研究所採樣臺灣黑豬飼養場間之類緣關係，以H-FABP、myogenin、myf6 及 CRC 4 個基因共 8 個基因座，以及前白蛋白與白蛋白 2 個血型基因座之多態性繪出類緣關係樹狀分佈圖。結果顯示，在 CRC 基因僅 Farm 5具多態性，而其餘 9 個基因座在本次採樣的 7 個民間臺灣黑豬飼養場均具有多態性變異。而由類緣關係樹狀分佈圖之結果可大致將本次採樣的臺灣黑豬飼養場分為 5 個集團，分別為 Farm 1 與 Farm 6、Farm 4 與 Farm 7、Farm 5、Farm 2 及 Farm 3。Farm 3 與其他 6 場的遺傳距離最遠，其原因可能是來自 Farm 3 的試驗豬隻品種來源多為盤克夏豬種。 綜上所述，為建立具本土特色的優質黑毛豬肉，必須先釐清臺灣黑豬在配種及飼養管理上之問題，故本研究蒐集分析目前臺灣地區黑毛豬在體型、屠體性狀及肌肉化學組成之資料，期提供未來更進一步建立臺灣黑豬育種策略、飼養管理模式及適用於臺灣黑豬的屠體評級之參考資料。

Taiwan pork industry was confronted with market impact after joining the WTO (World Trade Organization) in 2002. In 1999, Taiwan Livestock Research Institute (TLRI) bred the “TLRI No. 1 Black Pig” to establish a new local breed of black pigs for the pork market, but it’s not well accepted by pig farms. On the other hand, our current carcass grading system is not suitable for Taiwan black pigs because it is based on the lean content and black pig is emphasized on its intramuscular fat (IMF) content. For these reasons, we want to identify black pig body conformation parameters related to carcass composition, and suitable genetic markers for carcass traits and chemical composition of meats. In this study, we collected samples from 250 Taiwan black pigs in 7 different farms as experimental animals. Data collection includes body conformation measurements before slaughter, carcass traits, chemical composition (moisture, crude protein, crude fat contents) of the M. longissimus dorsi, and polymorphic genetic markers of heart fatty acid-binding protein (H-FABP) gene, muscle regulatory factor genes – myogenin and myf6, and calcium release channel receptor (CRC) gene by PCR-RFLPs. The results showed significant differences in body conformation measurements, carcass traits, chemical composition of the M. longissimus dorsi among the different farms (P<0.05). According to body conformation measurements, Taiwan black pigs can be classified into 3 body conformation types: meat, bacon, and lard. All of chest depth, chest width, chest girth, girth of limb, carcass length, backfat thickness, and intramuscular fat are significantly different among three body condition types (P<0.05). There were two restriction sites of myf6 gene for AvaI and BseRI sites and we found significant differences of body length, rump width, girth of limb, crude protein and crude fat content, and backfat thickness on the last lumbar in different genotype of the BseRI site (P<0.05), whereas no differences among the AvaI genotypes. There were no significant differences in body conformation measurements, carcass traits, and chemical composition of M. longissimus dorsi among different genotypes of myogenin and CRC genes (P>0.05). In order to understand the genetic similarity of Taiwan black pigs from different farms, the 8 loci of H-FABP, myogenin, myf6, and CRC, and 2 loci of serum protein polymorphisms were collected for gene constitution analyses. According to the matrix of genetic distance and cluster analysis, Taiwan black pigs from different farms could be divided into five groups: Farm 1 and Farm 6, Farm 4 and Farm 7, Farm 5, Farm 2, and Farm 3. In conclusion, chest depth, backfat thickness, and genotypes of the BseRI site of myf6 gene were suitable candidates as indicators and genetic markers to classify body conformation types. Furthermore, chest depth, chest width, chest girth, girth of limb, and carcass length can used to as references for establishing the carcass grading system specific for Taiwan black pigs.