MUC13 is a major gene that controls the susceptibility or resistance to diarrhea caused by ETEC F4 ac in piglets.In this study,the MUC13 resistant allele and performance traits of 3 successive generations of a nucleus Duroc breeding population,a total of 250 pigs,were determined using molecular and conventional breeding techniques to screen out the Duroc population homozygous for MUC13 resistant allele.Under the same feeding and management conditions,the occurrence of diarrhea in same-litter pre-weaned piglets from the 20 litters of breeding sows and 20 litters of propagating sows were 8.7% and 18.4%,respectively（P〈 0.01）.However,there was no significant difference in survival rate of same-litter weaned piglets from breeding sows and propagating sows（P 〈0.05）.The determination results showed there was no significant difference in days of age required by 1stgeneration and 3rd generation to grow to 100 kg of body weight.However,compared to that of the 1st generation,the live backfat thickness of the 3rdgeneration was reduced by 1.46 mm（P 〉0.05）.However,no significant differences in growth rate and live backfat thickness were found among the MUC13 genotypes from all the 3generations（P 0.05）.In conclusion,the homozygosis for the MUC13 resistant allele not only can control the occurrence of diarrhea in piglet but also can reduce significantly live backfat thickness.However,the homozygosis for the MUC13 resistant allele has no significant effects on growth and development of piglets.
