Effects of chromium-loaded chitosan nanoparticles on growth, carcass characteristics, pork quality, and lipid metabolism in finishing pigs

The study was conducted to evaluate the effects of chromium-loaded chitosan nanoparticles (Cr-CNP) on growth, carcass characteristics, pork quality, and lipid metabolism in finishing pigs. A total of 160 crossbred barrows with an average initial BW of 66.10±1.01 kg were randomly allotted to 4 dietary treatments, with 4 pens per treatments and 10 pigs per pen. Pigs were fed the basal diet supplemented with 0, 100, 200, or 400 μg/kg of Cr from Cr-CNP. All pigs were given free access to feed and water for 35 d. Two pigs from each pen were selected to collect serum samples and slaughtered to measure carcass characteristics and pork quality and collect adipose tissue samples. The results showed that gain to feed ratio of pigs fed supplemental Cr from Cr-CNP increased (P<0.05) compared with those fed the control diet. Dietary Cr-CNP increased the carcass lean ratio (P<0.01) and longissimus muscle area (P<0.05), decreased carcass fat ratio (P<0.001), and backfat thickness (P<0.01) linearly and quadratically. The 24 h drip loss was decreased (P<0.01) linearly and quadratically, while 45 min pH value and Hunter L, a, b values in longissimus muscle were unaffected with the dietary supplementation of Cr-CNP. Supplemental Cr from Cr-CNP increased serum free fatty acids (linear and quadratic, P<0.001), lipase activity (linear and quadratic, P<0.01), and serum insulin-like growth factor I (quadratic, P<0.01), while decreased serum insulin (linear, P<0.001). Dietary supplementation of Cr-CNP decreased activities of fatty acid synthase (linear and quadratic, P<0.01) and malate dehydrogenase (linear, P<0.01), while increased the activity of hormone-sensitive lipase (linear and quadratic, P<0.05) in subcutaneous adipose tissue. The present results indicated that dietary supplementation of Cr as Cr-CNP had beneficial effects on growth, carcass characteristics, and pork quality, and positively affected lipid catabolism in finishing pigs.