Effects Of Kitasamycin On Growth Performance,Residue In Tissues,Hind-gut Microbiota And Fat Metabolism In Pigs

Problems of environmental safety,livestock products safety and drug resistance resulting from widely used antibiotics for animals become increasingly serious.With the development of microbiology,an increasing number of researches showed that antibiotics resulted in fat metabolism disorder and did harm to animal.However,these results are inconsistent,and the underlying mechanism needs studying.Therefore,the present experiments were conducted to investigate the effects of different dosages of dietary kitasamycin,which is a kind of antibiotic allowed being used in feed,on growth performance,residue in tissues,hind-gut microbiota and fat metabolism in pigs.Effects of dietary addition of kitasamycin on growth performance,hind-gut microflora and fat content in tissues of weaned piglets24 healthy DLY weanling piglets(weaned at day 25)with an initial average body weight of 7.27±0.31 kg were randomly allocated to 4 treatments with 6 replicates per treatment and 1 pig per replicate according to the body weights,to feed with the basal diet(control group),basal diet + 50 mg/kg kitasamycin,basal diet + 200 mg/kg kitasamycin and basal diet + 400 mg/kg kitasamycin.The whole trial lasted for 28 days.In the morning of day 29,all the piglets were blooded,killed and sampled.The results were as follows:(1)When compared with the control group,200 mg/kg and 400 mg/kg kitasamycin decreased the diarrhea rate significantly(P<0.05).(2)When compared with the control group,50 mg/kg and 400 mg/kg kitasamycin decreased the index of pancreas significantly(P<0.05),50 mg/kg and 200 mg/kg kitasamycin decreased the relative density of small intestine siginificantly(P<0.05),and 200 mg/kg kitasamycin decreased the relative density of intestine siginificantly(P<0.05).(3)When compared with the control group,200 mg/kg and 400 mg/kg kitasamycin decreased the amount of Bifidobacterium in cecal content(P<0.05).(4)When compared with the control group,50 mg/kg kitasamycin increased the concentrations of acetic acid,propionic acid and total VFA in cecal content(P<0.05),and 400 mg/kg kitasamycin increased the levels of propionic acid and total VFA in cecal content and acetic acid in colon content significantly(P<0.05).(5)When compared with the control group,dietary kitasamycin supplementary had no significant influence on the concentrations of cholesterol and triglyceride in serum and IMF.These data indicated that dietary kitasamycin supplementary of weanling piglets decreased the diarrhea rateand the number of Bifidobacterium in cecal content.At the same time,low dose of kitasamycin increased the content of VFA in cecum digeta.Kitasamycin had no significant influence on fat content in tissues.Effects of dietary addition of kitasamycin on growth performance,hind-gut microflora,lipid metabolism and residue in tissues of growing pigs42 healthy DLY pigs with an initial average body weight of 63.32±1.00 kg were randomly allocated to 3 treatments with 7 replicates per treatment and 2 pigs per replicateaccording to the body weights,to feed with the basal diet(control group),basal diet + 50 mg/kg kitasamycin and basal diet + 200 mg/kg kitasamycin.The experiment was seperated into 2 periods including administation period(63 d)and withdrawal period(7 d).When the periods ended,pigs were blooded,killed and sampled.The results were as follows:(1)When compared with the control group,50 mg/kg and 100 mg/kg kitasamycin increased ADG and 50 mg/kg kitasamycin increased F/G in the period of 63-80 kg(P<0.05).However,dietary kitasamycin supplementary had no significant effect on growth performance of pigs from 80 kg to 100 kg and 100kg to 120kg.(2)When compared with the control group,50 mg/kg and 100 mg/kg kitasamycin groups had higher ATTD of ash(P<0.05),and 50 mg/kg kitasamycin increased the ATTD of DM,and 200 mg/kg kitasamycin increased the ATTD of GE in the period of 63-80 kg.From 80 kg to 100 kg,200 mg/kg kitasamycin had lower ATTD of EE and ash(P<0.05).When compared with the control group,50 mg/kg kitasamycin had lower ATTD of EE,and 200 mg/kg kitasamycin had higher ATTD of DM,CP and OM in the period of 100-120 kg(P<0.05).(3)When compared with the control group,50 mg/kg kitasamycin increased the averageback fat thickness remarkably(P<0.05).(4)When compared with the control group,200 mg/kg kitasamycin decreased the relative weight and the density of small intestine significantly(P<0.05).(5)When compared with the control group,50 mg/kg kitasamycin decreased the number of Bacillus significantly.50 mg/kg kitasamycin also decreased the number of Lactobacillus and Bifidobacterium(P<0.05)in cecum when campared with 200 mg/kg kitasamycin group.Furthermore,200 mg/kg kitasamycin decreased the number of Eschericha,Lactobacillus and Bifidobacterium in colon significantly(P<0.05)when compared with the control group.(6)When compared with the control group,50 mg/kg kitasamycin had higher contents of acetic acid,propionic acid,butyric acid and total VFA in cecum and colon(P<0.05).(7)When compared with the control group,50 mg/kg kitasamycin increased the concentration of serum total cholesterol.Lower serum contents of LPS and MDA were observed in 50 mg/kg and 200 mg/kg kitasamycin supplementary groups(P<0.05).(8)When compared with control group,50 mg/kg kitasamycin increased IMF and the mRNA expression of FAS,SCD,SREBP-1c,GPC-1? and IL-1?(P<0.05).(9)At the end of administration period,the content of kitasamycin in the liver of 50 mg/kg kitasamycin group was 4.55 ?g/kg in average.The contents of kitasamycin in the liver and rectum digesta of 200 mg/kg kitasamycin were 35.7 ?g/kg and 23176 ?g/kg,respectively.And in the urine and longissimus dorsi muscle,the content of kitasamycin was less than 1 ?g/kg.After 7 withdrawal days,the contents of kitasamycin in the liver of 50 and 200 mg/kg kitasamycin groups were less than 1 ?g/kg.These results indicated that dietary low dose of kitasamycin supplementary of pigs increased the content of VFA and decreased the amount of gram-positive bacterium in cecum,and improved the mRNA expression of fat metabolism related genes which resulted in fat deposition in longissimus dorsi muscle.However,high dose of kitasamycin affected the amount of microflora in colon and had no significant influence on fat depisition in longissimus dorsi muscle.Liver was the main residual tissue of kitasamycin,and most of the kitasamycin was eliminated from the faece.After 7 withdrawal days,the residue of kitasamycin in liver was absolutely gone.