Changes and Correlations of Duroc Muscle pH,Glycogen,Lactic Acid and TBA under Different Storage Condition

The changes and correlations of muscle pH, glycogen, lactic acid and in- tramuscular fat oxidation in Duroc pigs 10 d after their slaughter, and the effects of different storage temperature and time on Duroc muscle pH value, water loss rate, glycogen, lactic acid and 2-thiobarbituric acid （TBA） were studied. The results showed that during the 10 h after the slaughter, the pH value was decreased rapid- ly, the lactic acid content was increased significantly, while the glycogen and TBA contents were remained stable. At the storage temperature of 4 ℃, storage time showed no significant effects on Duroc muscle pH value and glycogen, lactic acid and TBA contents. At the storage temperature of -20 ℃, storage temperature had significant effects on pH value, while no significant effects on other indicators. The correlation analysis demonstrated that during the 10 h after the slaughter, the TBA content was negatively related to glycogen content （P〈0.05）, but positively related to lactic content （P〈0.05）; the pH value was negatively related to lactic acid content （P〈0.05）. At the storage temperature of 4 ℃, the TBA content was negatively relat- ed to water loss rate （P〈0.01） and lactic acid content （P〈0.05）; the water loss rate was positively related to pH value （P〈0.01） and lactic acid content （P〈0.05）. At the storage temperature of -20 ℃, the TBA content was negatively related to pH value （P〈0.01） and positively related to water loss rate （P〈0.05）; the water loss rate was negatively related to pH value （P〈0.01） and lactic acid content （P〈0.05）.

Breeding of Duroc Breeds Homozygous for MUC13 Diarrhea-resistant Allele

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.

Comparison of Semen Quality and Spermadhesins' m RNA Expression between Luchuan and Exotic Boars

Spermadhesins,as the most important components of boar semen seminoproteins,play a regulatory role in sperm motility,sperm capacitation and sperm-ovum fusion.In order to study the fertility differences among different boar breeds,the sperm motility,sperm viability and sperm deformity,as well as the spermadhesins＇ m RNA expression in fresh semen of Luchuan,Landrace and Duroc boars were compared.The results showed that the sperm motility and viability of Luchuan boar showed no significant differences with those of Landrace and Duroc boars（P〉 0.05）,but its sperm deformity was significantly lower than those of the other two exotic breeds（P〈0.01）;no significant differences were found in the m RNA expression levels of spermadhesins between Luchuan and Landrace,Duroc boars（P〉0.05）,excepting that the m RNA expression level of AQN1 in Luchuan boar semen was significantly lower than that in Duroc boar semen（P〈0.05）;the m RNA expression levels of AQN3,AWN and PSP-II in Landrace boar semen were significantly higher than those in Duroc boar semen（P〈0.05,P〈0.01）.In short,there were significant differences in the m RNA expression levels of spermadhesins among different pig breeds,which showed no significant correlations with the differences in sperm motility,viability and deformity.