Development Differences Of Growth And Muscle And Approach To The Mechanism In Jinhua Swine And Landrace

The study was to conducted to investigate the developmental changes of growth performance, muscle contents in growing Jinhua and Landrace pigs by determing' related hormone and gene expression of muscle developing. The objective of this study was to approach to the mechanism that breed and age affecting growth performance and muscle developing and supply scientific foundations for technology of regulating meat quality in pigs and utilization of hybridization between local and foreign breeds of pigs.A total of 36 purebred piglets (sex balance in each breed, weaned at 28 days of age) were allotted to two groups according to breed. Each group has three replicates with 6 piglets (sex balance) in each replicate. The feeding experiment lasted 90 days after a 7-day of adaptation period. Jinhua pigs and Landrace were reared in the same conditions. All pigs had ad libitum access to a experimental diet and water via nipple drinkers. At their predesignated slaughter age (at 35,80, and 125 days of age),6 purebred piglets (sex balance) of each breed were randomly selected and slaughtered to determine carcass composition. Samples of serum, and muscle were collected for subsequent analysis.The special primers for MSTN,MyOD,MyoG,MyHC I,2a,2b,2x and (3-actin were designed respectively according to the gene sequences reported previously in Genebank. The total RNA was extracted from muscle tissue of pigs and the target gene mRNA amplified through RT-PCR with special primers. The cDNA fragments of MSTN,MyOD,MyoG,MyHC I,2a,2b,2x and (3-actin were obtained. The PCR product was cloned into pUCm-T Vector and sequenced. Sequence analysis suggested that all the gene fragments gained in this study shared more than 98%indentity with the reported mRNA sequences of pig in Genebank. Based on the gene cloning, the suitable annealing temperature, Mg2+concentration, and cycles in PCR system were discussed and the optimal semi-quantitative RT-PCR methods were construced to determine the developmetal changes of related gene expressoin of muscle developing in growing Jinhua and Landrace pigs. The results of carcass evaluation indicated that the developmental changes of carcass composition and meat quality parameters in Jinhua and Landrace pigs followed the same age-dependent patterns. Compared with Landrace pigs, Jinhua pigs improved by 50.48%(P<0.05),50.00%(P<0.05),28.92%(P<0.05) in marbling score at 35,80 and 125 days of age, respectively. Meanwhile, there were increased by 31.25%(P<0.05) and 22.87%(P<0.05) in IMF and subjectives color score at 125 days of age, respectively. Whereas, Carcass lean percentage decreased by 35.99% (P<0.01),25.25%(P<0.01) and 29.94 (P<0.01), LMD by 20.73%(P<0.05),50.98% (P<0.01) and 50.20%(P<0.001), drip loss by 34.43%(P<0.05),34.00%(P<0.05) and 33.08%(P<0.05) at 35,80 and 125 days of age, respectively.Analysis of serum sample indicated that the developmental patterns of serum IGF-I, insulin, T3, T4 concentrations followed the same trends in Jinhua and Landrace pigs. Serum IGF-I concentrations increased with age (P<0.05), but serum T3 and T4 levels decreased with age (P<0.05). Compared with Landrace pigs, Jinhua pigs increased by 41.04%(P<0.05),53.04%(P<0.01) and 63.28%(P<0.01) in serum insulin concentration at 35,80 and 125 days of age, respectively. Whereas, serum IGF-I levels decreased by, by 38.13%(P<0.01),37.58%(P<0.01) and 19.77%(P<0.05), serum FT4 levels by 30.77%(P<0.05) at 80 days of age. And Jinhua gilts had lower serum GH concentration (baaal GH level, mean GH level and pulse amplitude) at 80 days of age.The developmental change of MSTN mRNA, MyoD mRNA and MyoG mRNA abundance followed the same trends in the two breeds (P<0.05). Compared with Landrace, Jinhua pigs decreased by 288%(P<0.01) 44.44%(P<0.05) and 27.27%(P<0.05) in MyoD mRNA level at 35,80 and 125 days of age, and 77.78% (P<0.05) in MyoG mRNA level at 35 days of age., the carcass meat content was markedly correlated with MyoD mRNA of Jinhua pigs (Jinhua pigs r:0.783 (P<0.05); Landrace pigs r:-0.888(P<0.05).The developmental change of MyHC I,2a,2,2x mRNA abundance followed the same trends in the two breeds (P<0.05). Compared with Landrace, Jinhua pigs increased by 15.01%(P<0.05),15.85%(P<0.05) and19.82%(P<0.05) in MyHC I mRNA,7.76%(P<0.05),22.10%(P<0.05) and 58.36%(P<0.05) in 2x mRNA, Whereas, decreased by 23.47%(P<0.05),9.12%(P<0.05) and 12.65%(P<0.05) in 2x mRNA level at 35,80 and 125 days of age, respectively.