Effect Of The Dietary Acidifier And Oregano Oil Instead Of Colistin Sulfate On Weaned Piglets

This experiment was conducted to study the effects of the acidifier and oregano oil instead of colistin sulfate on growth performance,intestinal health,and blood biochemical indicators of weaned piglets(14 day).A total of 120 crossbred piglets(Landrance×Large×Duroc),weaned at 26 days of age and 7.69±0.40 kg average initial body weight,were randomly divided into three groups,with five replicates in each group and eight piglets in each replicate.Fodder in each group were containing 75 mg/kg chlortetracycline and 10 mg/kg enramycin.In addition,pigs in three groups were fed 0.10% acidifier+0.10% colistin sulfate diets,0.15% acidifier diets,0.15% acidifier+0.03% oregano oil diets,respectively.The experiment lasted for 14 days.Experiment 1: On the first and the 14 th day of the experiment,the piglets were subjected to fasting individual weighed,the average daily gain was calculated in each repetition,and the corresponding feed consumption was recorded in groups.Calculate the average daily feed intake(ADFI),daily gain(ADG),feed weight ratio(F/G)and the rate of diarrhea.The results showed as follows: 1)There were no significant differences in ADG,ADFI,F/G and diarrhea rate(P>0.05)among different treatments.Compared with 0.10% acidifier+0.10% colistin sulfate group and 0.15% acidifier+0.03% oregano oil group,the 0.15% acidifier group had a trend to increase ADFI(P=0.066)and,respectively increased by 8.38% and 8.38%.2)The salmonella of cecum in 0.10% acidifier+0.10% colistin sulfate group were significantly lower than that in 0.15% acidifier group(P<0.05),the bifidobacteria and lactobacillus of cecum in 0.15% acidifier+0.03% oregano oil group were significantly higher than that in 0.15% acidulant group(P<0.05),but there were no significant differences between the 0.15% acidifier+0.03% oregano oil group and 0.10% acidifier+0.10% colistin sulfate group(P>0.05).Accordingly,on the basis of the added fodder of 75 mg/kg chlortetracycline and 10 mg/kg enramycin,the effects of 0.15% acidifier+0.03% oregano oil on the growth performance of weaned piglets were similar to colistin sulfate,0.15% acidulant+0.03% oregano oil also can increase the number of beneficial bacteria in cecum as colistin sulfate do.So the diets add acidifier and oregano oil can replace the colistin sulfate in piglets.Experiment 2: On the 14 th day of the experiment,after the piglets were sacrificed,the pH value of the contents of the stomach,duodenum,jejunum,ileum,cecum and colon(50 cm away from the blind junction)was measured immediately with a pH90 in-line pH meter,and recorded.After killing piglets,shearing piglet duodenum,jejunum,ileum in 4% formaldehyde solution fixed more than 24 h in jars,paraffin section HE dyeing observation piglets intestinal mucosal morphology.The jejunum mucosa was collected under aseptic conditions,stored in liquid nitrogen,and its digestive enzyme activity was measured using a kit.The results showed that: 1)No significant differences were observed in pH of gastrointestinal tract among different treatments(P>0.05).2)Compared with 0.10% acidifier+0.10% colistin sulfate group,the 0.15% acidifier+0.03% oregano oil group significantly increased the villus height of duodenum,jejunum and ileum,and increased the ratio between the villus height and crypt depth(V/C)of jejunum duodenum and ileum as well(P<0.05).The villus height of jejunum,ileum and V/C of duodenum in 0.15% acidifier+0.03% oregano oil group were significantly higher than 0.15% acidifier group(P<0.05).3)The pigs in 0.15% acidifier group and 0.15% acidifier+0.03% oregano oil group had significantly higher villus height of jejunum than that in 0.10% acidifier+0.10% colistin sulfate group(P<0.05).No significant differences were found in total protease and lipase activity among different treatment(P>0.05).The result demonstrate that 0.15% acidifier+0.03% oregano oil can reducing the gastrointestinal pH,improve the intestinal morphology and Jejunal mucosal amylase activity.Experiment 3: After 14 day,blood samples were collected from the anterior vena cava of piglets for 10 mL,and the serum biochemical indexes,antioxidation indexes and related enzyme activities were measured.The results showed as follows: 1)There was no significant difference in TP,ALB,TG,TC,GLU and BUN among different treatments(P>0.05).2)Compared with 0.10% acidifier+0.10% colistin sulfate group,the 0.15% acidifier group and 0.15% acidifier+0.03% oregano oil group significantly decreased the content of serum MDA,and significantly increased the serum T-AOC(P<0.05);No significant differences were observed in GSH-PX,T-SOD,CAT among different treatments(P>0.05).3)The active of Serum ALT and AST higher than 0.10% acidulant+0.10% colistin sulfate group and 0.15% acidulant+0.03% oregano oil group,but the difference was not significant(P>0.05).No significant differences were found in serum ALP,LPS,AMS(P>0.05).4)Serum IgG concentration in 10% acidulant+0.10% colistin sulfate group and 0.15% acidulant+0.03% oregano oil group were significantly increased than that of 0.15% acidifier group(P<0.05),whereas IgM,IgA,C3 and C4 were no significantly affected between different treatments(P>0.05).From these above results,it can be seen that the effect of 0.15% acidifier +0.03% oregano oil group on the serum biochemical indices of weaned piglets is equivalent to that of 0.10% acidifier + 0.10% sulfuric acid colistin,which can replace colistin sulfate for piglet diets.