Influences Of Different Dietary Nutrient Levels On Meat Quality And Intramuscular Fat Percentage Metabolism In Rongchang Pigs

There are two parts in this study, i.e, in vivo experiment and in vitro experiment. The experiments were carried out to study the effects of different dietary nutrient levelson meat quality and intramuscular fat (IMF) metabolism in Rongchang pigs. In the experiment in vivo 84 castrated Rongchang male pigs with 10kg weight were selected to study the effect of nutrient levels on performance and meat quality. The experiment pigs were divided randomly into 2 treatments groups, i.e, high dietary nutrient level one and low dietary nutrient level one. The diet for high nutrient level was formulated according to China Lean Type-pig Feeding Standard (Revision),and the diet for low nutrient level was formulated according to Rongchang pig(GB 7223-1987)Feeding Standard. One of the animals in the two treatments groups was slaughtered at different body weights, i.e, 10～20㎏,20~50㎏,50~80㎏ and 80~110㎏. Results showed as followed: (1)With the increasing of the body weight, feed/gain(F/G) in both experiments had a rising tendency in the whole period, daily gain appeared a peak value during 35～50kg,indicating that Rongchang pigs have fastest growth during 35～50kg;(2)Slaughter percentage, carcass length, carcass slant length also had increasing tendency,but loin eye muscle area had coutrary tendency;(3)Meat colors and marbling scores and intramuscular fat content at different body weights showed a rising tendency, but lean meat percentage showed a decreasing tendency. There was no significant difference in meat measurements between the two treatments. (4) Meat colors and marbling scores were directly affected by intramuscular fat contents, and the correlation coefficient was significant, and intramuscular fat contents gave significant influence on meat quality. With the increasing of intramuscular fat contents, meat quality was improved in the whole feeding period;(5)Serum TC,HDL-CHO and LDL-CHO parameters could showed a rising tendency with the increasing of body weight;(6)Ruducing the dietary nutrient level could decrease the serum TC,TG,HDL-CHO,LDL-CHO,VLDL-CHO and FFA contents;(7) There were significant differences in production performances,carcass and meat measurements at diffirent body weights(P<0.05).The experiment in vitro used tissue culture technique and minces was collected from longissimus muscle of 110kg Rongchang pigs.The trail was carried out in a 2×3 factorial design After primary culture, insulin and glucose solution were added to the culture media (Concentration of insulin was 10-5,10-7,10-9mol/L,and concentration of glucose was 16.4,5.0,0.5mmol/L respectively). Then total RNA were extracted at 2h, 6h and 16h, gene expression quantity of HSL, LPL, ACC, FAS were determined. The results showed that for the same concentration of glucose, with decreasing of insulin level, HSL mRNA contents was increased, LPL, ACC, FAS mRNA contents was decreased. And at the same concentration of insulin, with decreasing of glucose level, four enzymes gene expression quantity had the same tendency. This suggested that with decreasing of insulin or glucose levels, adipocyte lipolysis enhanced and synthesis weakened. With increasing of incubation time, four enzymes gene expression quantity was increased, indicating that, there was a dependence relation between four enzymes gene expression quantity and time. Insulin and glucose levels in culture media had interaction for four enzymes gene expression quantity and the effects were inclined to liposynthesis.