Effects Of High Fat Diet On Growing And Finishing Efficiency And Pork Quality Of IUGR Pigs

It has been shown that intrauterine growth retardation results in low birth weight. low birth weight in pigs has been associated with reduced postnatal growth rate and impaired pork quality. In order to clarify the effect of IUGR on growing and finishing efficiency and pork quality, and the regulatory effect of nutrition on growth performance and pork quality of IUGR pigs, present study was conducted to investigate the difference in growth performance, carcass traits, pork quality and lipid metabolism of NBW and IUGR pigs fed with feed varied in dietary fat content. A total of twenty NBW (BW1.83±0.17kg) and twenty IUGR (BW0.97±0.11kg) pigs weaned at28days were selected and fed with control diet (C) or high fat diet (HF,10%lard substituted for10%corn starch in control diet). Four experiment group was formed (birth weight/diet); NBW/C, NBW/HF, IUGR/C, IUGR/HF (n=10per group). The study was divided into4periods of28-56days (phase1),56-84days (phase2),84-140days (phase3), and140days of--slaughter (phase4). Growth performance, carcass traits, pork quality, lipid metabolism and related gene expression in muscle and fat tissue were measured at the end of experiment. The results showed as follows:(1) Birth weight had significant effect on growth performance of growth-fishing pigs. ADFI in all phases and ADG in previous3phases increased as birth weight increased (P<0.05). IUGR pigs utilized feed less efficiently than NBW pigs in phase1(P<0.01). Pigs fed with HF diet showed decreased ADFI and F/G in all phase (P<0.05). As dietary fat content increasing, ADG in phase3increased (P<0.01).(2) Regardless of age at slaughter, IUGR pigs had lower carcass weight (P<0.05). Compared with NBW, IUGR pigs at154days showed decreased dressing percentage and light value, and increased drip loss (P<0.05). IUGR pigs at178days exhibited increased lion-eye area, marbling score and shear force, and decreased pH45min and average back fat thickness (P<0.05). As dietary fat content increasing, IMF of IUGR pigs at154days increased (P<0.05).(3) As birth weight increasing,serum TC level significantly decreased (P<0.05) and TG level tended to be decreased (P=0.09). The concentration of TG, LDL and HDL in serum increased as dietary fat increased(P<0.05). As dietary fat content increasing, serum TC tended to be decreased and serum LDL be increased for IUGR pigs(P=0.07).(4) MDH activity in liver tended to be decreased as birth weight increased (P=0.07). As dietary fat level increasing, fat content in liver significantly increased (P<0.01). LPL activity in liver was significantly decreased and fat content was significantly increased of IUGR pigs that fed with HF diet (P<0.05).(5) As birth weight increasing, the level of LPL mRNA and SREBP-lc mRNA level increased (P<0.05); the level of SREBP-lc mRNA and HSL mRNA in fat tissue decreased (P<0.05). Increasing dietary fat content down-regulated the expression of ACC mRNA and LPL mRNA in muscle (P<0.05). The level of LPL mRNA and FAS mRNA level was significantly decreased in muscle of IUGR pigs that fed with HF diet (P<0.05)The results suggested that IUGR impair growth performance, carcass traits and pork quality of pigs and as the age increased, the difference between IUGR and NBW pigs decreased. Increasing dietary fat content improved growth performance and pork quality of IUGR pigs, but the level was still lower than NBW pigs. The possible mechanism that IUGR and dietary fat content had significant effect on growth performance and pork quality of pigs was related to the change of gene expressions associated with lipid metabolism.