| Dietary high doses of zinc oxide(2000-4000 mg/kg)supplementation has a significant effect on alleviating diarrhea in weaned piglets.However,it causes a lot of waste of zinc sources and serious environmental pollution.In order to reduce the amount of use,as well as reducing pollution.Porous zinc oxide is a new type of zinc source to be developed,which has a large surface area,uniform particles,good fluidity,high mixing uniformity,low residue,low pollution of heavy metals or other substances Cross-contamination may be small and less applicable in livestock production.The objective of the present study was to evaluate the effects of low-dose porous zinc oxide and nano-zinc oxide on weaned piglets,and investigated the effects of low-dose hydroxymethionine zinc replacement inorganic zinc on growth performance,blood biochemical indicators and apparent digestibility of nutrients in finishing pigs.Looking for a new alternative to high-dose zinc oxide and minerals to reduce trace elements.The main research contents and results are as follows:1.Effects of porous zinc oxide on growth performance,blood biochemical parameters and tissue micronutrients of weaned pigletsA total of 128 35-day-old "D × L× Y" healthy weaned pigs were selected and used single-factor trial design and randomly divided into 4 treatment groups with 8 replicates per treatment and 4 pigs per replicate(male and female each half).The four treatments were:basal diet group(blank control group),basal diet + feed grade zinc oxide(3000 mg/kg)(positive control group),basal diet + porous zinc oxide(200 mg/kg,500 mg/kg),the trial lasted 28 d.The results showed that the addition of porous zinc oxide(200 mg/kg or 500mg/kg)to the diets increased the average daily gain,average daily feed intake,and diarrhea rate of weaned piglets,and there was no significant difference between the diets and the high dose zinc oxide group(P> 0.05);Adding 500 mg/kg porous zinc oxide to diets significantly decreased serum aspartate aminotransferase activity and malondialdehyde content,and decreased zinc content in the liver(P<0.05),but had no significant effect on trace elementcontent in muscle(P>0.05).Adding 500 mg/kg porous zinc oxide or 3000 mg/kg zinc oxide to the diet significantly increased villus height in the jejunum and ileum,as well as the ratio of duodenum,jejunum and ileum villus height to crypt depth,while reducing duodenum.And jejunal crypt depth(P<0.05).In addition,the presence of porous zinc oxide in diets had no significant effect on serum amino acids(P>0.05).In summary,the addition of porous zinc oxide(200 mg/kg or 500 mg/kg)to the diet can increase the growth performance of weaned piglets,improve serum biochemical indicators and intestinal morphology,increase antioxidant capacity,and reduce zinc levels in the liver.High-dose zinc oxide,and applied to the actual production.2.Comparative study on replacement of high-dose zinc oxide with porous zinc oxide and nano-zinc oxide for weaned pigletsA total of 128 35-day-old "D × L× Y" three-way hybrid healthy weaned piglets were randomly divided into 4 treatment groups,each treated with 8 replicates and each with 4 pigs.The four treatments were basal diet group(blank control group NC),basal diet + 3000mg/kg feed grade zinc oxide(positive control group PC),basal diet + 500 mg/kg porous zinc oxide(HiZ)and Basic diet + 500 mg/kg nano zinc oxide(ZNP),28 days in the trial period.The results showed that ADG was significantly higher in PC and ZNP groups than in NC group(P <0.05).The incidence of diarrhea in HiZ group was similar to that in PC group(P>0.05).The diarrhea rate in HiZ group was lower than that in ZNP group(P> 0.05).There was no significant difference in the concentration of trace metal elements in the pig muscle of each experimental group(P> 0.05).Compared with the PC group,the zinc content of piglets in the HiZ and ZNP groups was significantly decreased(P <0.05),and there was no significant change compared with the NC group(P> 0.05).Adding different forms of zinc oxide to the diet had little effect on the concentration of other trace metals in the kidney(P>0.05).The duodenal villus height and jejunal crypt depth of piglets in PC group were higher than those in other groups(P <0.05).The depth of ileal crypts in PC,HiZ and ZNP groups was lower than that in NC and LHZ groups(P <0.05).The serum DAO activity in NC group was significantly higher than that in other groups(P <0.05).Compared with the NC group,the serum GSH-Px activity in the piglets fed with zinc oxide(PC,HiZ and ZNP groups)wasthe highest,and the MDA content was the lowest(P <0.05).The serum DAO,GSH of the piglets fed with the HiZ and ZNP feeds.-There was no significant difference in Px and MDA levels(P> 0.05).Compared with the HiZ and ZNP groups,the IFN-γ mRNA expression in the duodenum and ileum of the PC group was down-regulated(P < 0.05).Dietary supplementation of zinc oxide(PC,HiZ,and ZNP groups)up-regulated the mRNA expression of TFF3 and Nrf2(P < 0.05).In duodenum and ileum,the expression level of TFF3 mRNA in HiZ group was lower than that in ZNP group(P < 0.05).Compared with ZNP group,the expression of Nrf2 mRNA in HiZ group was decreased,and the expression of Nrf2 jejunum mRNA was increased(P < 0.05).In general,porous zinc oxide and nano zinc oxide can be used as substitutes for high-dose common zinc oxide for weaned pigs.3.Effect of low-dose hydroxymethionine zinc replacement inorganic zinc on growth performance,blood biochemical indicators and apparent digestibility of nutrients in finishing pigsA total of 300 "D× L × Y" finishing pigs(75kg ± 1)were randomly selected and divided into 5 treatment groups,each treated with 6 replicates and 10 replicates each.D1 group was fed the basal diet.In group D2,the basal diet was reduced by 60% copper and zinc.In group D3,the basal diet was reduced by 60% copper and zinc + 14 mg/Kg NCG-Cu.The group D4 was fed the basal diet.60% copper zinc + 417mg/Kg hydroxyl methionine zinc chelate,D5 group feeding basal diet decreased by 60% copper zinc + 14mg/Kg NCG-Cu + 417mg/Kg hydroxyl methionine chelate zinc.The results showed that finishing pigs fed with NCG diets significantly reduced the average daily feed intake(P=0.044),and had a tendency to decrease the feed-to-meat ratio(P=0.062),but the average daily pig growth among other groups was increased.There was no significant difference in weight,average daily feed intake,and feed/feed ratio(P > 0.05).There was no significant difference in serum alanine aminotransferase(ALT),alkaline phosphatase(ALP),aspartate aminotransferase(AST)activity,and albumin(ALB)and urea nitrogen(UREA)content in finishing pigs of the experimental groups(P > 0.05).The serum globulin(GLB)content in D4 group was significantly higher than that in control group and 60% copper group(P <0.05),but there was no significant difference between D3 group and D5 group(P > 0.05);the serum creatinine(CREA)content in D3 group The highest was significantly higher than the other experimental groups(P < 0.05).There was no significant difference in serum creatinine among the other experimental groups(P > 0.05).There was no significant difference in serum immunoglobulin A and immunoglobulin M content in finishing pigs between the experimental groups(P > 0.05).Serum Ig was highest in the D4 group,which was significantly higher than that in the D5 group(P < 0.05).There was no significant difference in other groups(P > 0.05).There was no significant change in apparent digestibility of crude protein,calcium,and iron in finishing pigs(P > 0.05).The apparent digestibility of phosphorus in D2 group was the lowest,significantly lower than that in D3,D4,and D5 groups(P < 0.05).There was no significant difference between the two groups(P > 0.05).The apparent digestibility of zinc and copper in D4 group was significantly higher than that in D1 and D2 groups(P < 0.05),but there was no significant difference between D3 and D5(P> 0.05).In summary,the addition of porous zinc oxide(200 mg/kg or 500 mg/kg)to the diet can improve growth performance of weaned piglets,improve serum biochemical indicators and intestinal morphology,increase antioxidant capacity,and enhance intestinal immunity.Zinc content in the liver can replace high-dose zinc oxide and is applied to actual production.In addition,the addition of low-dose hydroxymethionine zinc instead of inorganic zinc to diets had no effect on the growth performance of finishing pigs,which could improve blood biochemical indicators and increase the apparent digestibility of zinc and copper. |
