Effects Of Zinc-Bearing Palygorskite On Apparent Nutrient Digestibility,Antioxidant Capacity And Expression Of Zinc Transporter Protein Gene Of Intestine In Weaned Piglets

The purpose of this thesis was inducted to investigate the effects of zinc-bearing palygorskiteinstead of antibiotic(kitasamycin)and ZnO on growth performance,intestinal morphology,serum biochemical parameters,antioxidant function and expression of Zinc transporter-related genes in weaned piglets.A total of 128 hybrid weaned piglets(Duroc×landrace×large white)with an average initial body weight of 8.59±0.40 kg at age of 25 d were randomly divided into 4 groups with 4 replicates of 8 piglets per replicate with male and female half.Piglets in the four groups were fed a basal diet supplemented with 110 mg·kg-1antibiotic and 2 000 mg·kg-1 ZnO(Control group),55 mg·kg-1antibiotic and 1 000 mg·kg-1 ZnO and 2 000 mg·kg-1 Zinc-bearing palygorskite(Zn-Pal)(Exp.Ⅰ),2 000 mg·kg-1Zn-Pal(Exp.Ⅱ),4 000 mg·kg-1Zn-Pal(Exp.Ⅲ),respectively.Experimental periods were 35 d in duration,including 7 d adaptation and 28 d date collection and sampling period.At the end day of the test,one piglet with similar body weight from each replicatewas randomly selected,weighed,slaughtered and sampled.The experiment was divided into three parts:Experiment 1 Effects of zinc-bearing palygorskite on growth performance,organ index,intestinal morphology and serum biochemical parameters in weaned pigletsThe present study was conducted to evaluate the effects of Zn-Pal instead of antibiotic and ZnO on growth performance,organ index,intestinal morphology and serum biochemical parameters in weaned piglets.The results showed that the dietary supplementation of Zn-Pal instead of antibiotic and ZnO did not significantly effects on average daily gain and feed to gain ratio in piglets(P>0.05);There were no significant differences in the diarrhea rate and the diarrhea index between Exp.Ⅲ group and control group(P>0.05),however the diarrhea rate in Exp.Ⅱ group was significantly higher than other groups(P<0.05).The indexes of heart,spleen and kidney in Exp.Ⅱ and Ⅲ group were significantly lower than control group(P<0.05),whereas,pancreas index was higher than Exp.Ⅰ group(P<0.05).The serum content of total protein and globulin in Exp.Ⅲ group was significantly higher than Exp.Ⅰ group(P<0.05),while the albumin content and the ratio of albumin to globulin were significantly lower than control group(P<0.05).The contents of triglyceride and total cholesterol in Exp.Ⅱ and Ⅲ group were significantly lower than control group(P<0.05).The serum content of urea nitrogen in control group was significantly lower than other groups(P<0.05).The serum content of high density lipoprotein and low density lipoprotein in Exp.Ⅲ group was significantly higher than Exp.Ⅱ group(P<0.05),and the low density lipoprotein content was significantly lower than control group(P<0.05).Compared with control group,the pH value of chyme in the stomach of piglets in Exp.Ⅲ group decreased slightly,however,there was no significant difference between the two groups(P>0.05).The apparent digestibility of nutrients in Exp.Ⅲ group was significantly higher than Exp.Ⅰ and control group(P<0.05).The crypt depth of control group was significantly higher than the other three groups(P<0.05).The villus height of each segment in Exp Ⅰ and Ⅱ group was significantly lower than Exp.Ⅲ and control group(P<0.05),but the jejunal crypt depth in Exp.Ⅲ group and villus height to crypt depth ratio in control group was significantly higher than other three groups(P<0.05).zinc-bearing palygorskite had no significant effects on the activities of lipase and amylase(P>0.05),but significantly increased the activities of trypsin and chymotrypsin(P<0.05)in the pancreas in weaned piglets.The activities of trypsin and chymotrypsin in Exp.Ⅲ and control group were significantly higher than Exp.Ⅰ and Ⅱ group(P<0.05).Experiment 2 Effects of zinc-bearing palygorskite on tract element content of liver,blood and feces in weaned pigsThe present study was conducted to evaluate the effects of zinc-bearing palygorskite instead of antibiotic and ZnO on tract element content of liver,blood and feces in weaned piglets.The results showed that the zinc content of liver in Exp.Ⅱ and Ⅲ group was significantly decreased(P<0.05),compared with control group.The iron contents of liver in Exp.Ⅰ group and Exp.Ⅲ group wwer significantly lower than Exp.Ⅱ and control group(P<0.05)The manganese contents of liver in Exp.Ⅰ,Ⅱ and Ⅲ group were 9.68%,16.13%and 9.38%higher than control group(P<0.05).Compared with control group and Exp.Ⅱ Group,the copper content of liver of Exp.Ⅲ group was significantly decreased(P<0.05),the zinc content blood of Exp.Ⅲ group was significantly higher than other groups and Exp.Ⅱ group was significantly higher than control group(P<0.05).The iron content of blood in control group was significantly higher than other groups and Exp.Ⅲgroup was significantly higher than Exp.Ⅰ group;The zinc content of feces in Exp.Ⅱ andⅢ group were significantly lower than control group and Exp.Ⅰ group(P<0.05).but the iron contents of feces were significantly higher than control group and Exp.Ⅰ(P<0.05).The copper contents of feces and manganese in Exp.Ⅰ group were significantly lower than other three groups(P<0.05).Experiment 3 Effects of zinc-bearing palygorskite on antioxidant function and expression of zinc transporter-related genes in weaned pigletsThe present study was conducted to evaluate the effects of zinc-bearing palygorskite instead of antibiotic and ZnO on antioxidant function and expression of zinc transporter-related genes in weaned piglets.The results showed that serum T-AOC activity in Exp.Ⅱ group was significantly lower than Exp.Ⅰ and Ⅲ group(P<0.05),and serum T-SOD activity in Exp.Ⅱ group was significantly lower than Exp.Ⅰ group(P<0.05),serum T-SOD activity in Exp.Ⅲ group was slightly higher than control group(P<0.05),the serum CuZn-SOD activity in Exp.Ⅱ group was significantly lower than the other groups(P<0.05),and the CuZn-SOD activity of serum in Exp.Ⅲ group was not significantly different from control group(P>0.05).The serum contents of MDA in Exp.Ⅱ and Ⅲ group were significantly lower than Exp.Ⅰ and control group(P<0.05).In the liver,T-AOC capacity in Exp.Ⅲ group was significantly higher than other groups(P<0.05),and Exp.Ⅱ group was significantly lower than control group and Exp.Ⅰ group(P<0.05).The activities of CAT and CuZn-SOD in Exp.Ⅱ and Ⅲ group were significantly higher than Exp.Ⅰ group and control group(.P<0.05),and the activity of GSH-Px in Exp.Ⅱ group was significantly lower than Exp.Ⅲ group and control group(P<0.05).Compared with other three groups,the expressions of ZIP-4 and DMT1 gene were significantly increased by Exp.Ⅲ group in duodenum mucosa(P<0.05),the expression of ZnT-1,ZnT-2 and ZnT-5 gene in duodenum mucosaof control group were significantly higher than other three groups(P<0.05).Compared with other three groups,the gene expression of ZIP-4 was significantly increased(P<0.05),but the gene expression levels of ZnT-1,ZnT-2,and DMT-1 were significantly lower(P<0.05)in jejunum mucosa in Exp.Ⅲ group.The expression of ZnT-5 geneofjejunum mucosa in Exp.Ⅲ group was lower than control and Exp.Ⅰ groups.The expressions of ZIP-4,ZnT-1 and ZnT-5 of Ileum mucosa in Exp.Ⅲ group were significantly lower than other three groups(P<0.05),but ZnT-2 no difference(P>0.05).The expression of DMT-1 gene of Ileum mucosa in Exp.Ⅲ group was significantly lower than control and Exp.Ⅱgroups(P<0.05).Taken above together,under the experimental condition,zinc-bearing palygorskite insteadof antibiotic and ZnO had no different effect on performance,can decrease diarrhea rate,improve the blood routine indexes and reduce zinc excretion of feces,and up-regulated expression of ZIP-4 gene induodenum and jejunum mucosain weaned piglets.