Effect of different protein and limiting amino acid levels coupled with a supplement of chromium picolinate on lipid metabolism and carcass characteristics of pigs

This study investigated the response of different dietary protein and limit ing amino acid concentrations coupled with a supplement of chromium in grow ing-finishing pigs. Sixty Landrace X Yorkshire X Duroc bacon type pigs With an initial live weight of 33.08 (s.d. 4.80) kg were randomly assigned into six groups with an equal number of males and females. They were given diet s containing proportionately 1.0, 1.1 or 1.2 of the National Research Counc il recommendation of crude protein and limiting amino acid (lysine and meth ionine) levels and coupled with supplementing chromium at 0 or 200 mu g/kg in the form of chromium picolinate (Crpic). The experiment was completed wh en the pigs' live weight reached 120 kg. Experiment results indicated that different nutrient levels or Crpic supplement did not significantly affect pig growth (P > 0.05). However, both nutrient levels and Crpic supplementat ion increased gamma-globulin concentration (P<0.05). In addition, Crpic sup plement not only significantly reduced the backfat thickness, serum insulin level and VLDL-C + LDL-C concentration (P < 0.05) but also increased the l oin-eye area and HDL-C concentration of pigs (P < 0.05). On the other hand, the particle sizes of HDL and VLDL were decreased and increased (P < 0.05) , respectively. In addition, Crpic supplement increased the activities of a dipose tissue lipogenesis related enzymes such as fatty acid synthetase, AT P-citrate cleavage enzyme and NADP-malic dehydrogenase (P < 0.05 to 0.001). In a similar manner, Crpic supplement increased the activities of adipose tissue lipoprotein lipase and serum lecithin-cholesterol acyltransferase (P < 0.05). However, the interactions of nutrient levels X Crpic supplementat ion were insignificant (P > 0.05). Results in this study demonstrated that chromium picolinate supplement created a beneficial effect but supplements of chromium coupled with high dietary protein and limiting amino acid level s were unnecessary for bacon-type pigs.