以遺傳標幟進行台灣黑毛豬生產模式與生長、屠體性狀及肌肉化學組成評估之探討

Abstract

台灣於 2002 年加入世界貿易組織 (World Trade Organization, WTO)，由於進口豬肉較便宜，國內養豬產業受到強大的市場壓力，所以發展出具有本土特色之品牌豬肉成為重要的課題。台灣黑豬的肉含有豐富的肌內脂肪 (intramuscular fat, IMF)，使得肉質鮮美，能夠做出市場區隔，所以台灣黑豬可以做為本土特色之品牌豬肉的來源。 由於民間黑豬場的種原及配種策略無法確知，為了解台灣黑豬的種畜來源及類緣關係，本研究收集了來自於 8 個不同豬場共 299 頭台灣黑豬及台灣現有之豬隻種原的樣本，包含杜洛克、藍瑞斯、約克夏、盤克夏、畜試黑豬一號、桃園豬及梅山豬，利用 15 組微衛星標幟進行試驗，並以 PHYLIP 軟體計算遺傳距離，以瞭解台灣黑豬與各豬種間的類緣關係。結果顯示 Farm 1、2、3、4、5、7 及 8 與杜洛克、藍瑞斯及畜試黑豬一號分在同一群組，顯示其種畜來源類似；Farm 6 與盤克夏分在同一群組；桃園豬與梅山豬分在同一群組，藉由結果可了解各豬場台灣黑豬所使用的種原有所差異，但仍可發現主要的種原有杜洛克、藍瑞斯、畜試黑豬一號及盤克夏。 為瞭解不同豬場之台灣黑豬在體型測量值、屠體性狀及第 9~10 肋間腰眼肌肉化學組成的差異，選取了來自 8 個不同豬場共 434 頭台灣黑豬進行試驗。結果顯示 Farm 3 之台灣黑豬有較好的體型表現且其整齊度高；在屠體性狀方面，Farm 5 及 8 有較厚的背脂厚度，而 Farm 3 的背脂厚度則較薄；在肌肉化學組成方面，Farm 3、4 及 5 有較高的肌內脂肪含量。綜上所述，可發現 Farm 3 之台灣黑豬的整體表現較好，似乎可作為台灣黑豬最適生產模式的參考。 本研究選用兩種與豬隻生長及屠體性狀有關的基因-第一型及第二型類胰島素生長因子 (insulin-like growth factor I and II, IGF-I and IGF-II)，利用 PCR-RFLP 技術進行台灣黑豬遺傳多態性的分析，結果發現 IGF-I 基因的 HhaI 切位的不同基因型只有在胸深有顯著差異，其餘性狀皆無顯著差異，而 IGF-II 的NciI 切位的不同基因型對於背脂厚度及肌內脂肪量有顯著差異，顯示 IGF-II 的NciI 切位可作為選拔背脂厚度及肌內脂肪量的篩選基因。 為瞭解台灣黑豬的生長狀況，本試驗選用與 Farm 3 有類似種原的黑豬進行生長試驗，結果發現生長曲線呈現類似斜線且平穩的趨勢，顯示台灣黑豬體重於100 公斤後仍維持穩定的增重速率，可能是背脂厚度的增長速率增加所造成。此外可發現本試驗之台灣黑豬之日增重及肌內脂肪含量有較畜試黑豬一號高的趨勢，且本試驗之台灣黑豬在 50 及 95 公斤體重時之背脂厚度較畜試黑豬一號薄，在 130 公斤體重時之背脂厚度有薄於畜試黑豬一號在 120 公斤體重時之背脂厚度的趨勢，且肌內脂肪量有高於畜試黑豬一號的趨勢。顯示本試驗之台灣黑豬在生長及屠體性狀表現優於畜試黑豬一號，似乎是較畜試黑豬一號好的黑豬生產模式。 由上述試驗結果可知，Farm 3 之台灣黑豬有不錯的體型表現、較薄的背脂厚度及較高的肌內脂肪量，似乎是較好的黑豬生產模式，且透過生長試驗可發現，本試驗台灣黑豬在日增重及屠體性狀的表現上都優於畜試黑豬一號，更適合作為台灣黑豬的最適生產模式。而透過 NciI 切位之 IGF-II 基因之選拔，可使台灣黑豬具有高肌內脂肪量，增加豬肉的附加價值。透過各項試驗，期望本研究可作為台灣黑豬最適生產模式的參考之一。

Taiwan had played a member of World Trade Organization (WTO) in 2002, so the pork industry was confronted by import pressure. To deal with this problem, the stockbreeders tried to establish a new local brand focusing on Taiwan black pigs. The meat of Taiwan black pigs is more popular in Taiwan because of its higher intramuscular fat content (IMF%). Nevertheless, the productive models of Taiwan black pigs in different farms were uncertain. Therefore, the first experiment was to investigate parental breeds of Taiwan black pigs by using 15 pairs of microsatellite markers. Total of 299 Taiwan black pigs from 8 private farms, 38 Taoyuan, 32 Meishan, 12 Berkshire, 31 Duroc, 21 Landrace, and 33 Yorkshire pigs were analyzed. The genetic distance among these pig breeds was calculated by PHYLIP software. From the genetic distance viewpoint, the results showed that farm 1, 2, 3, 4, 5, 7, 8, Duroc, Landrace and TLRI black No. 1 pig were grouped. Farm 6 and Berkshire were grouped. Meishan and Taoyuan were grouped. The breeding policies of productive models were different among farms, but we could figure out that Duroc, Landrace, TLRI black No. 1 pig and Berkshire might be the major parental breeds of Taiwan black pigs in the study. In order to understand the difference of body conformations, carcass traits, and chemical compositions of M. longissimus dorsi of Taiwan black pigs between different farms, we sampled 434 Taiwan black pigs in 8 different farms. The results showed that Taiwan black pig from the farm 3 had better performance of body conformation and higher uniformity than others. In carcass traits, backfat thickness of Taiwan black pigs from farm 5 and 8 were thicker than others while pigs from farm 3 had thinner backfat. In addition, the results showed Taiwan black pigs from farm 3, 4, and 5 had higher IMF% in chemical composition of muscle. Taken together, the performances of body conformation, carcass traits, and chemical composition of muscle in Taiwan black pigs from farm 3 were better than pigs from other farms. It was indicated that Taiwan black pigs from farm 3 might be more suitable productive model. Moreover, we picked up two genes, IGF-I and IGF-II, which was related to growth and carcass traits for genotyping by PCR-RFLP. The results showed body conformations, carcass traits, and chemical compositions of muscle were not significant different among pigs with different IGF-I genotypes (P＞0.05), but there were significant differences of backfat thickness and IMF% (P<0.05) among different genotypes of IGF-II gene. In order to predict the model of growth rate of Taiwan black pigs, we selected black pig that the breed was similar to farm 3 to do the growth test. The results showed the growth curve of Taiwan black pigs grew steady. Because the growth rate of backfat increased, the weight of Taiwan black pig maintained steady gain after 100 kg. In addition, the average daily gain and intramuscular fat of Taiwan black pigs in this study were higher than TLRI black No.1 pigs. The backfat thickness of Taiwan black pigs were thicker than TLRI black No.1 pigs at 50 and 95 kg, but the backfat thickness of Taiwan black pigs at 130 kg were thinner than TLRI black No.1 pigs at 120 kg. Besides, the intramuscular fat of Taiwan black pigs were higher than TLRI black No.1 pigs. It showed that the productive model of black pigs in this study were better than TLRI black No.1 pigs. These results suggested that Taiwan black pig from farm 3 had better performance of body conformations, thinner backfat thickness, and higher IMF%. It was the better productive model of Taiwan Black pig. In addition, daily gain and carcass traits of Taiwan black pigs were better than TLRI black No.1 pigs in this test. Meanwhile, IGF-II gene might be a genetic maker which could increase IMF%. It could increase additional value of meat. Throuh test, we expected that this research could become a reference of optimal productive model of Taiwan black pigs.