Study Of The Effect Of High-Dosage Of PGRF Gene Plasmid On Pigs' Growth

This study was carried out to examine the effect of high injected dosage of pGRF on pigs' growth and to verify its security in production. Single factor design was adopted.56 three-line crossbred weaned piglets were allotted to 8 groups(initial weight:7.82?0.26kg),each group have the same weight, sex and genetic character. The 8 groups were allotted to 4 treatments, there were 2 replicates in per treatment. The treatments were: (1) Saline was injected; (2) 3mg pGRF was injected in the first day of experiment; (3) 3mg pGRF was injected in the first day, 3mg was injected again 45 days later; (4) 3mg pGRF was injected in the first day, 6mg was injected again 45 days later. During the experiment food-intake and weight-gain were noted. Feeding experiment was ended at the 150th day, 8 pigs in per treatment were slaughtered. Before slaughter 20ml blood was taken out from vein and then divided into three portions. General parameter in blood, biochemistry parameter in serum and hormone in plasma were detected respectively. After slaughter a bitofheart, liver, spleen, lung and kidney were taken from each pig for histopathology observation. A bit of heart, live, spleen lung, kidney - muscle from injected position and non-injected position was taken to detect the remnant of plasmid.Results showed: Compared to the control group,3mg dosage made ADG-. ADFI> F/G increase 0.84%, 4.23% and 3.37% respectively, but difference was not significant. 6mg dosage made ADG% ADFI and F/G decrease 3.2%, 4.59 and 1%, difference was not significant. 9mg dosage made ADG decrease 4.62%, F/G increase 4.71%, difference was not significant. The total trend was high injected dosage restrained growth performance .higher dosage and stronger restrained effect. 3mg and 6mg can make pig's weight of liver significantly decrease, but won't do harm to pig's health in other aspects. 9mg dosage made platelet significantly decrease(p<0.01),creatine in serum significantly increase(p<0.05), and granule degeneration happen in liver and kidney. pGRF gene plasmid had no significant effect on carcass composition but could improve the quality ofpork in some aspects. By the end of the experiment, the level of GH, GRF, SS in the plasma of each treatment all declined to normal level and had no significant difference compared to the control group. The plasmid's remnant can't been detected in the hear, liver, spleen, kidney, muscle from injected position and non-injected position of 3mg and 6mg groups. The plasmid's remnant, just 0.00014% of initial injection dosage, could only been detected in the muscle of injected position in 9mg group. These suggested injected dosage don't exceed 6mg was safe for pig.