a1 Department of Animal Science, , National Chiayi Institute of Technology, Chiayi, Taiwan, ROC
a2 Department of Food Industry, National Chiayi Institute of Technology, Chiayi, Taiwan, ROC
This study investigated the response of different dietary protein and limiting amino acid concentrations coupled with a supplement of chromium in growing-finishing pigs. Sixty Landrace × Yorkshire × 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 diets containing proportionately 1·0, 1·1 or 1·2 of the National Research Council recommendation of crude protein and limiting amino acid (lysine and methionine) levels and coupled with supplementing chromium at 0 or 200 ng/kg in the form of chromium picolinate (Crpic). The experiment was completed when 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 supplementation increased y-globulin concentration (P < 0·05). In addition, Crpic supplement not only significantly reduced the backfat thickness, serum insulin level and VLDL-C + LDL-C concentration (P < 0·05) but also increased the loin-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 adipose tissue lipogenesis related enzymes such as fatty acid synthetase, ATP-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 × Crpic supplementation 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 levels were unnecessary for bacon-type pigs.
(Received December 22 1997)
(Accepted June 23 1998)