Fluorosis, caused by excessive fluoride ingestion, is an important public health problem all over the world. It has been reported that areas of endemic fluorosis occur in all inhabited continents (1). This condition is rampant in China. Except for the municipality of Shanghai, every province in China has areas that are afflicted with endemic fluorosis (2), with nearly 70,000,000 patients with fluorosis (3). In fluoride-contaminated areas, animals are as severely affected as humans are. In addition to endemic and industrial fluorosis, more mineral supplements added to diets with increasing development of the feed industry are direct important sources of excess fluorine intake by animals, which seriously affect their growth and production. The studies on the adverse effects of high fluoride ingestion on the health and performances of animals started early in the 1930s. However, most experiments had been conducted to study fluorosis in avian species, cattle, rabbits and sheep, little data were reported in pigs, especially since the 1980s. Yet fluorosis in pig groups in China was frequently reported in recent years. So it is necessary to determine the adverse effects of fluoride levels on pigs.Depending on this, in this study it was mainly assessed the effects of excessive fluoride ingestion on growth performance, serum indexes and antioxidant systems in growing pigs. Methods Experimental designA total of 96 crossbred growing pigs (68d) weighing 24.14±1.12 kg were randomly assigned to four treatments. These treatments containing the following added fluorine (as NaF) levels: 0, 50, 100 and 150 mg/kg fluorine were randomly assigned to four replications with 6 pigs (3 barrows and 3 gilts) per pen in a completely randomized design. Pigs were allowed ad libitum access to feed and water during the experiment. The experiment lasted 84 days after a 7-day adaptation period. All diets were formulated to meet or exceed the requirements described by the NRC (4). Fluorine content was 37.39

The experiment was conducted to evaluate effect of dietary bovine lactoferrin (bLF) on lipid peroxidation and activities as well as mRNA levels of antioxidant enzymes of piglets. Duroc × Landrace × Yorkshire crossbred female piglets (n=120, 35 days of age, liveweight 9.70 ± 0.71 kg) were fed a diet containing 0, 1250, or 2500 mg/kg bLF for 30 days. After completion of the feeding experiment, twelve female piglets with 4 animals in each treatment were randomly selected to determine malondialdehyde (MDA) and total antioxidant capacity (TAOC) levelsczinc-superoxide dismutase (CuZnSOD), glutathione perioxidase (GPx), catalase (CAT) activities in serum and liver, and CuZnSOD, GPx and CAT mRNA levels in liver. Results showed that piglets treated with 2500 mg/kg bLF significantly increased (P<0.05) TAOC levels, the activities of GPx, CuZnSOD and CAT, and mRNA levels of CuZnSOD, GPx and CAT, and decreased (P<0.05) the contents of MDA as compared with control. Supplementation with 1250 mg/kg bLF also increased (P<0.05) the activities of CuZnSOD, GPx and CAT and mRNA levels of GPx and CAT, and decreased (P<0.05) the contents of MDA as compared with control, but the effect was not better than that of dietary addition of 2500 mg/kg bLF (P<0.05). The study indicated that addition of bLF improved the antioxidant function of piglets by up-regulation of mRNA levels and activities of certain antioxidant enzymes associated with free radicals metabolism.