臺灣黑毛豬生產特性及法國本地豬種 Basque 與法國大白豬生產性能比較之研究

Abstract

本論文包括兩部分的試驗，其一為針對臺灣黑毛豬所進行的試驗分析，另一部分則為針對法國當地豬種 Basque 豬及法國大白豬所進行的試驗分析。 自 2005 年全面開放國外畜禽產品進口後，臺灣黑毛豬在臺灣肉品市場中成為具有競爭力的一個品項。「臺灣黑毛豬」指的身被黑毛的豬隻，而非指單一品種或品系；因此，臺灣黑毛豬的特性需要藉由科學方法有系統地進行相關研究；此部份的試驗採用了 500 頭臺灣黑毛豬 (收集時間自 2006 年至 2008 年) 。利用微衛星標幟分析所得之結果可將臺灣黑毛豬與其他純種豬隻群集化 (cluster)；相對於中國系豬種，臺灣黑毛豬與歐洲系豬種的親緣關係較近。此結果說明在臺灣黑毛豬的育成過程中，歐洲系豬種最常被用來進行生長 (例如：生長速率及飼料效率) 及屠體性狀 (例如瘦肉率) 的遺傳改進，特別是杜洛克品種。在臺灣，豬隻拍賣及買賣主要是根據對豬隻外表的主觀判定，使得體型特徵在黑毛豬育種中顯得非常重要。本試驗以典型相關分析找出七項體型測量值與屠體性狀間的關聯性，發現體高、胸深及胸圍與屠體重及屠體背脂厚度的關聯性最高；然而，更多的屠體及肉質性狀應該一同列入分析，以提高體型測量值對於預測屠體性狀之準確度。肌肉生成過程是決定產肉量及肉質的關鍵步驟，主要是由肌肉調控因子 (MRF) 基因家族所控制。在 myogenin 及 myf6 基因與臺灣黑毛豬及 DL 豬隻性能表現之相關性分析結果中發現，在以臺灣黑毛豬及 DL 豬隻之屠體組成為目標的育種計畫下，位在 myogenin 基因上的 MspI 限制酵素切位及位在 myf6 基因上的 BseRI 限制酵素切位具有作為候選基因的潛力 (P<0.1)；然而，此二個變異點可能會因品種或族群的不同 (臺灣黑毛豬 vs. DL 豬隻) 以及性別的不同 (DL 豬隻 --- 閹公豬 vs. 女豬) 而對於表型有不同程度的影響。 第二部分的試驗是以飼養在不同型畜舍的法國當地的 Basque 豬種 (B) 及法國大白豬 (LW) 進行性能比較，收集的性狀包括生長、屠前血液生化值、肌纖維組成、肉的化學組成、脂肪酸組成、物理性質地分析與脂肪/蛋白質氧化程度分析及品評。畜舍類型分成三種，第一種是傳統型 (C)、第二種為替代型 (L)、以及第三種為粗放型 (E)，在約兩公頃的戶外空間進行放牧，並有屋舍以供遮蔽。因此，本試驗可分為五組：BC、BL、BE、LWC 及 LWL，每組的樣本數均為 10。結果顯示，雖然「品種」為影響性能表現的主要因子 (P<0.05)， L 型畜舍對於豬隻的性能表現並無顯著的不良影響；因此，在動物福利的考量之下，L 型畜舍可以應用在法國 Basque 豬及大白豬的生產系統中。相反地，飼養在 E 型畜舍的 Basque 豬隻在生長性能的表現較差，且其肉質較硬，顯示出粗放型態容易受到許多環境因子的影響而不易管理，包括氣候、溫度及飼料供給與食物採集。另一方面，為找出各性狀間的關聯性，利用以偏相關 (partial correlation，又稱為淨相關) 為基礎的 Graphic Gaussian model (GGM) 建構出一個綜觀的網絡 (overview network)，並以 R 統計軟體中的 GeneNet 套組進行分析。所得之網絡圖像顯示兩個主要結果：第一個是利用綜觀的網絡可以呈現整體目標性狀間的直接關係，包括與已知性狀間相關性相同或是不同的結果；第二個則是由特定目標性狀為節點構成的次網絡 (subnetwork) 可以用來篩選出較具有重要性的相關性狀。此網絡分析的結果可以提供後續的試驗假設及實驗驗證之參考依據。 對於臺灣黑毛豬與法國本地豬種 Basque 而言，仍然有許多品種特性需要藉由科學方法定義及證明，例如營養需求及繁殖表現。性能改良及妥善利用其特殊性是未來進行臺灣黑毛豬相關研究的重要課題。從動物福利以及經濟的觀點綜合來看，粗放行的飼養方式對於本地豬種不見得是最佳的飼養環境；此外；無論是商業豬種 (例如，法國大白豬) 或是本地豬種 (例如，Basque 豬種)，如何在豬隻生產性能與其動物福利之間取得平衡將會是未來關注的研究方向之一。

Two parts of experiments are included in the present dissertation: one is on the Taiwan black pig, and the other is on French Basque and French Large White breeds. Taiwan black pig (TBP) has competitiveness in the meat market in Taiwan under the pressure of the import of livestock and poultry products since 2005. As 'Taiwan black pig' is a general term of pigs covered with black hair, the characteristics of TBP have to be scientifically and systematically determined. The present work collected 500 TBP in the commercial slaughter plant during 2006--2008. Microsatellite markers were used to cluster TBP and other purebred pigs on the basis of Nei's genetic distance, and the result indicated that TBP in the pork market was more similar to the European than Chinese breeds. This finding coincided with the fact that the European breeds, especially the Duroc breed, were the most often used to improve the growth performance (e.g., higher growth rate and better feed efficiency) and carcass quality (e.g., higher lean percentage) of TBP in Taiwan. In Taiwan, the auction and the trading of pigs are carried out according to subjectively appearance judgment, which makes the body conformation characteristics standing out in breeding TBP. By canonical correlation analysis between the seven measurements of body conformation and carcass traits, body height, chest depth and chest circumference turned out to be the major parameters related to carcass weight and backfat thickness. However, more items of carcass and meat quality traits are needed for examining the correlation strength of these parameters in the future. Myogenesis is an important process in determining the quality and quantity of meat production, which is mainly regulated by the muscle regulatory factor (MRF) gene family. Two MRF family genes --- myogenin and myf6, were included in the genetic association study in the TBP and the commercial Duroc×Landrace (DL) pigs. The results revealed that the MspI site at the myogenin gene and the BseRI site at the myf6 gene had potential to be candidate genes in the breeding of the TBP and the DL pigs to improve carcass composition (P<0.1). Nevertheless, those two sites were breed- or population-dependent (TBP vs. DL pigs) and sex-dependent (castrated male vs. female DL pigs). In the second part, two genetically distant breeds, French Basque (B) and French Large White (LW) pigs, were used to investigate the effects of breed and housing system on production performance traits, including growth, slaughter reactivity, muscle fiber composition, chemical and fatty acid composition, technological quality and lipid/protein oxidation of meat and sensory evaluation. The housing systems were the conventional (C), alternative (L) and extensive (E); thus, there were five groups of treatments --- Basque pigs in three types of housing systems and Large White pigs in C and L types of housing systems (10 pigs/each group) in the experiment. Although the breed effect was the major factor affecting production performance traits (P<0.05), no adverse effect of the L system on production performance indicated that the L system can be used in pig production of the Basque and the Large White breeds from the welfare-oriented point of view. Inferior growth performance and tougher meat of the Basque pigs in free-range rearing system indicated disadvantages in environmental and management factors, such as climate, ambient temperature and feeding regime. Additionally, the same data set was used to infer the direct interactions using a shrinkage approach based on the graphic Gaussian models (GGMs) through partial correlation; the R-package GeneNet was applied to construct the network. The major results revealed: (1) an overview network presented the direct connections of investigated variables through partial correlation estimations, where some were similar to or different from the known correlations between those variables; and (2) the extracted subnetwork with interested variables filtered out the more important related variables. The most needed validation of future work can be identified according to the results of networks. For both TBP and the French Basque breed, there are still a lot of breed-characteristics needed to be scientifically elucidate, such as nutrition requirement and reproduction performance. Performance improvement and well-utilization of the unique characteristics are the major targets in the future studies of TBP. From the welfare-oriented and economic points of view, the extensive rearing system may not always be the most suitable to the native pig breeds; additionally, a balance between production performance and animal welfare should be considered for both conventional breeds (e.g., Large White pig) and local breeds (e.g., Basque pig).