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

Two parts of experiments are included in the present dissertation: one is on the black pig, and the other is on French Basque and French Large White breeds. black (TBP) has competitiveness in the meat market in 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 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 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).