| This study contained three trials, and conducted to compare the effects of high level copper or pharmaceutical zinc oxide on growth performance, gut development, and microbial number of weanling piglets, then researched the effects of levels of Cu as copper sulfate on growth performance, and cecal ecosystem in pigs after weaning, furthermore, investigated whether increasing levels of zinc and iron was necessary for high copper diet.Experiment 1 was conducted to investigate the effects of high dietary concentrations of Cu as copper sulfate and Zn as zinc oxide on the growth performance, activity of digestive enzymes, intestinal morphology, and cecal ecosystem in piglets after weaning. One hundred and five pigs (DLY) weaned at 25±1 d of age were randomly allocated to 3 treatments with 5 replicates of 7 piglets per replicate. The pigs were fed basal diet and basal diet supplemented with Zn(2500 mg/kg) or Cu(250 mg/kg) for a 28-d period. At the end of 21-d, one pig was chosen from per replicate to kill. The results showed that adding pharmacological levels of Cu and Zn improved the ADG by 23.16%(p<0.01) and 19.66% (p<0.05), decreased the F/G by 12.78%(p<0.01) and 6.67%(p>0.05) respectively. Pancreatic amylase increased (p<0.05) in pigs fed 250 mg/kg of Cu and 2500 mg/kg of Zn, Pepsin increased(p<0.05) in pigs fed 250 mg/kg of Cu. Pigs fed high dietary Cu and Zn had greater villous length and the ratio of villous length to crypt depth (VCR) of ileum, jejunum and duodenum, and VCR of ileum increased significantly(p<0.05). The amounts of Escherichia coli, Lactobacilli and Bacillus bifidus in cecum tended to reduce in pigs fed high dietary Cu and Zn. In summary, high dietary Zn or Cu increased the performance, activity of several digestive enzymes, villous length and VCR, and reduced the amounts of several microorganism in the cecum. High dietary Cu had better effects than high dietary Zn.Experiment 2 was conducted to investigate the effects of levels of Cu as copper sulfate on the growth performance and cecal ecosystem in pigs after weaning. One hundred pigs (DLY) weaned at 28±2d were randomly allocated to 4 treatments with 5 replicates of 5 piglets per replicate, sex was balanced in each treatment. The pigs were fed two-phase basal diets, or diets containing 100, 175, or 250 Cu mg /kg for a 28-d period. Digestive trial was conducted for 4 d on d 17, 18, 19, 20 of the experiment. One from each pen was slaughtered on d 21 of the experiment. The results showed that adding high levels of Cu improved the ADG by 26.92%(p>0.05), 51.10%(p<0.05) and 59.90%(p<0.05), decreased the F/G by 10.50%(p>0.05), 20.59%(p<0.05) and 15.55%(p<0.05) compared to the basal diet, respectively. And the high level supplementation of Cu had significant effect on the apparent digestibilities of crude protein(p<0.05), ether extract(p<0.05), calcium(p<0.05) and phosphorate(p<0.05) of the diets. 250 mg/kg copper diet significantly enhanced abundance of jejunum IGF-I mRNA14.49% and TLR9 mRNA49.07%(p<0.05), and elevated serum IgA16.19% and IL-2 47.30%(p<0.05) in pigs, compared to the basal diet.The amounts of Escherichia coli and Lactobacilli in cecum tended to reduce, while the concentrations of cecal volatile fatty acids was increased in pigs fed high levels of Cu. Supplementing diets with copper could reduce the microbe diversities in cecum according to the PCR-DGGE analysis. It was indicated that dietary supplementation with copper could improve growth performance, nutritional digestibility and cecal microbiota.Experiment 3 was conducted to investigate the effects of high dietary concentrations of Cu as copper sulfate and, Zn as zinc sulfate and Fe as ferrous sulfate on the growth performance, intestinal morphology and cecal ecosystem in piglets after weaning, and to decide whether necessary increased the level of zinc and ferrum. Thirty-two pigs (PIC) were weaned at 25±1 d of age. The pigs were fed weaning diets supplemented with Cu (10 or 250 mg/kg), and Zn-Fe (100 or 200 mg/kg) in a 2×2 factorial arrangement of treatments for a 21-d period. The pigs were allocated randomly to 4 treatments with 8 pigs by weight. At the end of the experiment, five pigs from each treatment were slaughtered. During the experiment, pigs fed 250 mg/kg Cu diets enhanced ADG(p=0.051) by 11.3%, and had a significant decrease the diarrhea index(p<0.05). During the first week, there was a Cu×(Zn-Fe) interaction on the diarrhea index(p<0.05). In the content of jejunum, the activity of lipase was greater in pigs fed 250 mg/kg of Cu(p=0.076). There was a Cux(Zn-Fe) interaction(p<0.01) in amylase activity. A higher copper significantly elevated the TLR9 mRNA abundance in jejunal mucosa compared to the basal copper level. The trend was an increase in villis height and the ratio of villous length to crypt depth in pigs fed 250 mg/kg Cu, and had highly significant decrease crypt depth (p<0.01). High dietary copper tended to decrease area of jejunal neutral mucin cells(p=0.055). A highly significant interaction between copper and zinc& iron was also observed on the area of jejunal neutral mucin cells(p<0.01). Pigs fed the diets supplemented with Zn-Fe tended to improve the villous length and crypt depth, had a significant enhance the ratio of villous length to crypt depth. There was a Cu×(Zn-Fe) interaction(p<0.01) in villis height and the ratio of villous length to crypt depth. The trend was an reduction in number of microorganism and the microbe diversities in cecum of pigs fed supplemented with the higher copper, and the higher Zn-Fe diets had a significant decrease the number of lactobalillus(p<0.05) and Acidobaterium(p<0.05).There was no Cu×(Zn-Fe) interaction in number of microorganism and the microbe diversities in cecum. In summary, higher copper diets would rather not add zinc and ferrous on the growth performance. in short period.The results showed that dietary supplementation of high level copper was better than pharmaceutical zinc oxide on growth-promoting effect in early weaned piglets. The optimal copper level was 175-250 mg/kg, and it was unnecessary to increase zinc and iron levels in short-term additional high copper diet. The growth-promoting effect of high copper must be associated with improving gut microbial profile, decreasing diarrhea and increasing the digestibilities of nutrients. |
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