豬大腸桿菌F4ab/ac抵抗力相關基因單核苷酸多態型對藍瑞斯、約克夏及杜洛克豬生長性能與屠體性狀之影響

Abstract

Diarrhea of neonatal and weaning pigs is a serious disease in pig industry. Enterotoxigenic E. coli (ETEC) expressing F4 fimbriae is a common porcine enteric pathogen, causing diarrhea in new born and weaning pigs, and edema disease in pigs after weaning. The F4 fimbriae are filamentous surface appendages that allow the bacteria to attach to F4 variant specific receptors on brush borders of enterocytes, and then to colonize the small intestine of piglets. The locus controlling susceptibility towards ETEC F4ab/ac has been mapped to SSC13q41. The mucin 4 (MUC4), mucin 13 (MUC13) and transferrin receptor (TFRC) genes have been proposed as candidate genes for the disease resistance to ETEC F4ab/ac. However, there was still no report on the possible effect of selecting resistance to ETEC F4ab/ac on the growth performance and carcass traits in pigs. The purpose of this study was to investigate the effect of single nucleotide polymorphisms (SNPs) in ETEC F4ab/ac resistance-related genes on the growth performance and carcass in purebred pigs in Taiwan. For evaluating the effect of selecting SNPs on growth performance, 1480 centrally performance tested purebred boars (1057 Duroc, 317 Landrace, and 106 Yorkshire) were used. The performance traits included average daily gain, feed conversion ratio, backfat thickness, age at 110 kg of body weight, and body weight at 150 days of age. The selection index of each individual was also calculated. For carcass traits, a total of 159 purebred pigs (100 Duroc, 47 Landrace and 12 Yorkshire) from a commercial farm were used. There were 74 males and 85 females. The carcass traits included dressing percentage, backfat thickness at the first-rib, the last-rib, and the last lumbar backfat and pH value of ham and loin muscle at 45 minutes and 24 hours postmortem. The genotypes of MUC4, MUC13 and TFRC SNPs were determined by polymerase chain reaction based restriction fragment length polymorphism. The results indicated that there was no polymorphism in TFRC. The allelic frequencies of the ETEC F4ab/ac susceptive G allele in MUC4-C8227G in centrally performance tested Duroc, Landrace, and Yorkshire pigs were 0.02, 0.46, and 0.51, respectively. The allelic frequencies in the pigs from the commercial farm in female were 0.04, 0.50, and 0.60. In males, the allelic frequencies were 0.05, 0.42, and 0.07. The allelic frequencies of G allele in MUC13-A908G in the centrally performance tested boars were 0.50, 0.71, and 0.62 in the three breeds of pigs. The allelic frequencies of MUC13-A908G in female pigs of the three breeds from the commercial pig farm were 0.53, 0.80, and 0.50. In males, the allelic frequencies were 0.42, 0.77, and 0.50. Results of statistical analysis revealed that there was no significant effect of the SNPs in MUC4 and MUC13 on the growth performance in Duroc and Yorkshire (P>0.05). The SNP in MUC4 showed significant effect on days of age arrive 110 kg body weight and body weight at 150 days of age of Landrace boars. For carcass traits, the susceptible GG type in MUC13 showed higher pH value than other genotypes. The results of this study suggested that selecting disease resistance to ETEC F4ab/ac by SNPs in MUC4 and MUC13 may not affect the growth performance in Duroc and Yorkshire pigs, but may affect the growth of Landrace pigs. However, the effect of SNP in MUC13 on carcass traits requires further validation.