RESUMO
The study was conducted to investigate the effect of copper-loaded chitosan nanoparticles on the composition and metabolism of the caecal microbiota in rats. Forty male Sprague-Dawley (SD) rats (average body weight of 82 ± 5 g) were randomly assigned to five groups (n = 8). The dietary treatments were: (i) basal diet, (ii) basal diet + 80 mg/kg BW CuSO(4), (iii) basal diet + 80 mg/kg BW chitosan (CS-I), (iv) basal diet + 80 mg/kg BW copper-loaded chitosan nanoparticles (CSN-I) and (v) basal diet + 160 mg/kg BW copper-loaded chitosan nanoparticles (CSN-II). The trial lasted 21 days. The results showed that compared with control, Average day gain (ADG) of group CSN-I and CSN-II increased (p < 0.05). No significant difference was found in CuSO(4) or CS-I-treated groups (p > 0.05). There were no effects of these treatments on average day feed intake (ADFI) of rats (p > 0.05). The counts of Bifidobacteria and Lactobacillus in group CSN-II were higher than those of the control group (p < 0.05), while the counts of total aerobes, total anaerobes, Salmonella, Clostridium and coliform were lower than those of the control (p < 0.05). The activity of ß-glucuronidase in group CSN-I or CSN-II was significantly depressed (p < 0.05), while the activities of α-galactosidase and ß-galactosidase were enhanced significantly (p < 0.05). The pH of the caecum digesta and the concentration of propionate and butyrate in group CSN-I and CSN-II were higher than those of the control group (p < 0.05). No significant difference was found in these parameters in CuSO(4) or CS-I-treated groups (p > 0.05). The results indicate that the microbiota and environment of caecum are beneficially changed by the administration of copper-loaded CSN.