Effect Of PGRF Gene Plasmid On Growth Performance And Neuro-endocrine Somatotropic Axis Hormone In Pigs

The following two experiments were undertaken to evaluate the effects of porcine growth hormone-releasing factor gene plasmid(pGRFGP)on growth performance and Neuro-endocrine somatotropic axis hormones in pigs.In the first experiment,24 duroc×large white×landrace crossbred barrow pigs were arranged into two groups. Pigs of treatment were injected 4.5mg pGRF and pigs of control group were injected 2 mL saline(0.9%). the results showed that: the pGRF gene plasmid increased the ADG of pigs in the injected group by 13.3%(p<0.05),the F/G and ADFI dropped by 4.9%(p>0.05),16.1%(p<0.05)than the control in 1d~30d; between 31d and 60d,the effect of the pGRF gene plasmid is not evident; In entire growing period,the pGRFgene plasmid dropped the F/G by 10.5%(p<0.05)(.1)compared to growth performance, improvement feed efficiency was more marked in entire growing period.(2)the effect of porcine growth hormone-releasing factor gene plasmid on growth performance was weaking with the pig growing. The effect was better in foretime.In the second experiment, 10 duroc×large white×landrace crossbred barrow pigs were arranged into two groups at random after blood Catheter was surgically installed in the jugular vein for each pig. Pigs of treatment were injected 4.5mg of pGRF and pigs of control group were injected 2 mL saline(0.9%).On 30d repeated it. Samples of plasma were taken on different days and assayed the concentration of GRF,SS,GH and IGF-1. after 5 days post-injection, the GH concentration increased significantly than the control(p<0.05).the GH concentration reached the tiptop on the 12th day and was 1.57 times(p<0.01)higher than the contro, after then,the concentration of treatment decreased step by step and end up with the concentration of the control; the GRF concentration reached the tiptop on the 12th day, was 1.43times higher than the control(p<0.01),1.325 times higher than the control(p<0.05).after 17days, the concentration of treatment decreased step by step and end up with the concentration of the control. The SS concentration did not change significantly;(2)in this experiment, The gene plasmid started in 5~8 days to release slowly, achieved the peak on the 12th day.(3)after secondary injection pGRF gene plasmid, From the 33th day, the GH concentration escalate, the GH concentration reached the tiptop on the 12th day and was 1.44 times(p<0.05) higher than the control; the IGF-1 concentration of the 39th,45th,60th,22th day were 1.66 times (p<0.05), 1.73 times(p<0.05),1.17 times(p<0.05)higher than the control; the GRF concentration reached the tiptop on the 12th days, was 1.38 times higher than the control(p<0.05), The concentration did not change significantly on other days. The SS concentration did not change significantly on entire days.(4)the result of correlation analysis showed that after injected the pGRF gene plasmid ,the GRF was significantly related to the GH positively(P<0.01),the corelative coefficient was 0.81;the SS was related to the GH negatively,the correlative coefficient was -0.65;the GRF,GH was related to the IGF-I positvely,the SS was related to the IGF-I negatively.the GH was related to the IGF-I positively significantly(P<0.05),the correlative coefficient was 0.67.