Effects Of I3C On Meat Quality,Serum Biochemical Indexes,Behavior And Cecal Microbiota Of Immune Stressed Rabbits

The purpose of this study was to investigate the effects of indole-3-methanol(I3C)on growth performance,slaughter performance under normal feeding conditions and meat quality,serum biochemistry,behavior and cecal microbiota under immune stressed conditions of Hyla rabbits.Forty 50 days old rabbits with similar body weight were divided into four groups:Group Control,basal diet+40 mg/kg I3C(Group I3C),basal diet+LPS(Group LPS),basal diet+LPS+40 mg/kg I3C(Group LPS+I3C).I3C was dissolved in DMSO(8%)corn oil.Group Control and Group LPS were given the same dose of solvent.The experiment lasted for 21 days,including 7 days of pre feeding and 14 days of trial.On the day of slaughtering,Group LPS and Group LPS+I3C were intraperitoneally injected with 0.5 mg/kg LPS,while Group Control and Group I3C were injected with the same dose of saline.The growth performance was recorded in the trial period,and the slaughter performance,meat quality,serum biochemical indexes,behavior records within 4 h after injection and cecal microbiota were carried out after slaughter.The results show that:(1)Compared with Group Control,I3C significantly reduced the feed conversion ratio(P<0.05),but had no significant effect on the initial body weight,final body weight,weight gain and feed intake(P>0.05).(2)There was no significant effect of I3C on the eviscerated carcass weight percentage,semi-eviscerated carcass weight percentage and organ index(P>0.05).(3)There was no significant difference in thymus weight,spleen weight and spleen index among the four groups(P>0.05).The interaction between I3C and LPS had significant effect on thymus index(P<0.05).The thymus index in Group I3C was significantly higher than that in Group Control(P<0.05).(4)The interaction of I3C and LPS had significant effects on pH,L*,b*,shear force(24 h after slaughter)and mass loss,pH,b*(5 d after slaughter)of longissimus dorsi(P<0.05),and also had significant effects on pH(24 h after slaughter)and mass loss,pH,L*,a*(5 d after slaughter)of biceps femoris(P<0.05).The pH of longissimus dorsi(24 h after slaughter)and the shear force of biceps femoris in Group I3C were significantly higher than those in Group Control(P<0.05).The pH(24 h after slaughter)of longissimus dorsi and the cooking percentage of biceps femoris in Group LPS were significantly higher than those in Group Control(P<0.05).Shear force of longissimus dorsi,mass loss and pH(5 d after slaughter)of biceps femoris were significantly lower than those of Group Control(P<0.05).The weight loss of longissimus dorsi in Group LPS+I3C was significantly lower than that in Group LPS(P<0.05).Feeding I3C can improve the meat color of immune stressed rabbits.(5)The interaction of I3C and LPS had significant effect on the content of MDA in longissimus dorsi 5 days after slaughter(P<0.05).Intraperitoneal injection of LPS significantly increased the content of MDA on both 24 hours and 5 days after slaughter(P<0.05),while I3C can significantly reverse those effect(P<0.05).(6)The interaction of I3C and LPS had significant effects on serum ALP,UREA,TP,ALB and TC(P<0.05).The contents of serum TP,ALB in Group I3C were significantly higher than those in Group Control(P<0.05),and the contents of TC in Group I3C were significantly lower than that in Group Control(P<0.05).Compared with Group LPS,the contents of ALT,ALP and UREA in Group I3C+LPS were significantly decreased(P<0.05),and the content of CREA was decreased,but the difference was not significant(P>0.05).Compared with Group Control,the contents of UREA and CREA in Group LPS were significantly increased(P<0.05),while the contents of TP,ALB and TC were significantly decreased(P<0.05).(7)Compared with Group Control,the frequency and duration of biting behavior in I3C group were significantly decreased(P<0.05),and the frequency and duration of sniffing behavior were significantly increased(P<0.05).Compared with Group LPS,the frequency and duration of lying behavior in Group LPS+I3C were significantly decreased(P<0.05),and the frequency of self modification,sniffing and digging behavior were significantly increased(P<0.05).Compared with Control Group,the frequency of lying,self modification and exercise behaviors and the duration of lying behavior in Group LPS were significantly increased(P<0.05),while the frequency of drinking and digging behaviors and the duration of eating,drinking,self modification,biting,fecal eating and digging behaviors in Group LPS were significantly decreased(P<0.05).The interaction of I3C and LPS had significant effect on the frequency of sitting and self modification behaviors(P<0.05).(8)Alpha diversity analysis showed that the interaction of I3C and LPS had significant effect on Ace and Chao1 index of cecal microorganisms(P<0.05).There was no significant difference in Shannon index and Simpson index among the four groups(P>0.05).At phylum level,the dominant phylum of cecal microorganisms in the four groups were Firmicutes,Bacteroidetes and Verrucomicrobia.There was no significant difference in the abundance of dominant phylum among the four groups(P>0.05).The interaction between I3C and LPS had significant effect on Proteobacteria.The abundance of Proteobacteria in Group I3C was significantly lower than that in Group Control(P<0.05).At the family level,the relative abundance of Ruminococcaceae,Muribaculaceae and Lachnospiraceae were relatively high.I3C had significant effect on Ruminococcaceae(P<0.05).In conclusion,I3C can improve growth performance,reduce stereotyped behavior and play a positive role in the growth and animal welfare of meat rabbits.Under LPS stimulation,I3C can alleviate organ damage,delay onset time,improve cecal microbial structure and effectively alleviate the body damage caused by immune stress.