Effects of nanoparticle chromium mixed with γ-polyglutamic acid on the chromium bioavailability, growth performance, serum parameters and carcass traits of pigs

Because chromium is a mineral that is difficult to absorb, nanotechnology was used to produce nanoparticle trivalent chromium, which has a reduced particle size and increased surface area to increase chromium bioavailability. The aim of the present study was to investigate the effect of dietary supplementation nanoparticle trivalent chromium with or without gamma-polyglutamic acid (gamma-PGA) on the chromium bioavailability, growth performance, serum parameters and carcass traits of pigs. In Trial 1, eight growing pigs (Landrace x Yorkshire x Duroc; LYD) with an initial average weight of 51.3 +/- 2.0 kg were used in a 4 x 4 Latin square design as the control group (without chromium supplements), the chromium picolinate group (CrPic), the nanoparticle chromium picolinate group (NanoCrPic) and the nanoparticle chromium picolinate mixed with gamma-polyglutamic acid (NanoCrPic-PGA) group. Chromium was added at a level of 200 mu g/kg to a basal diet containing 728 mu g Cr/kg DM, using different forms of chromium, so as to evaluate the chromium bioavailability. The results of Trial 1 indicated that the bioavailability of the supplemented chromium was as follows: NanoCrPic-PGA > NanoCrPic > CrPic (P < 0.05). In Trial 2, 64 LYD growing pigs (average bodyweight 74.46 +/- 3.9 kg) were randomly allotted to the same four dietary treatment groups as in Trial 1 and the same levels of chromium were added to the diet. Each group contained four pens and there were four pigs in each pen. The experimental results indicated that the gain : feed ratio in the NanoCrPic-PGA group was better than that in the NanoCrPic group (P < 0.001). The serum chromium concentrations in the NanoCrPic-PGA group were higher than in the control group (P < 0.05), the serum insulin concentration in the chromium supplementation groups was lower than that in the control group (P < 0.05), and blood glucose in the NanoCrPic group was lower than that in the control group (P < 0.05). The carcass traits were not affected by chromium supplementation. In conclusion, nanoparticle trivalent chromium, either alone or together with gamma-PGA, improved chromium bioavailability and feeding effectiveness.