Effects Of Yucca Extract And Clostridium Butyricum On Growth Performance And Intestinal Health Of Weaned Meat Rabbits

This experiment aimed to investigate the effects of dietary supplementation of yucca extract(YSE)alone and in combination with Clostridium butyricum(C.butyricum)alone or in combination on the growth performance,nutrient digestibility,meat quality,gut barrier,and metabolites of weaned meat rabbits.Using completely randomized design,a total of 400 33-day-old weaned meat rabbits with similar average body weight(1.05 ± 0.02 kg)were randomly divided into 4 treatment groups for 40 d:(1)basal diet group,(2)basal diet contained 300 mg/kg of yucca extract,(3)basal diet supplemented with 0.4 × 1010 colony-forming units(CFU)/kg of C.butyricum,and(4)the blend of 0.4 × 1010/kg CFU of C.butyricum and 300 mg/kg of yucca extract.Each group had five replications,and each replication included 20 rabbits.Regarding to growth performance,meat quality,and nutrient apparent digestibility,when compared with the Ctrl group,dietary YSE treatment significantly increased the body weight of meat rabbits at 50 and 60 d,daily weight gain from d 40-50 and 40-80,and decreased the diarrhea rate(P < 0.05).Adding C.butyricum to the diet significantly increased the body weight of meat rabbits at 60 d and increased the feed intake from 40 to 60 d(P < 0.05).Dietary YSE and C.butyricum in combination notably increased the body weight and weight gain of meat rabbits at 60,70,and 80 d(P < 0.05),and increased carcass properties(P < 0.05).Considering the meat quality,supplementation YSE and C.butyricum to the diet significantly reduced the water loss rate,drip loss,and muscle shear force of the longest back muscle,and increased the p H45 min of the muscle and crude fat content(P < 0.05).In addition,the dietary treatment had no significant difference in crude fat digestibility of meat rabbits,but dietary YSE or C.butyricum inclusion to the diet could remarkably increase the digestibility of crude protein,acid detergent fiber,and calcium of rabbits.As far as serum biochemical indices and antioxidant capacity concerned,dietary treatment significantly increased the concentration of total protein,albumin,and globulin in the serum and reduced the level of serum urea nitrogen as compared with the Ctrl group(P < 0.05).The urea nitrogen content of the YSE + C.butyricum group was significantly lower than that of the alone C.butyricum and YSE groups(P < 0.05).The YSE + C.butyricum group also remarkably reduced the activity of alanine aminotransferase and aspartate transferase.Adding YSE and C.butyricum to the diet can increase the total antioxidant capacity(TAC)and superoxide dismutase activity in the serum,muscle,and intestine,as well as increase the glutathione peroxidase activity in the muscle,intestine,and liver,whereas it reduced the content of malondialdehyde in the serum,liver,muscle,and intestine(P < 0.05).When considering the intestinal barrier and cecal microbiota,the outcomes showed that supplementing YSE and C.butyricum to the feed significantly increased the villi height,decreased crypt depth,and increased the villus-to-crypt ratio as compared to the Ctrl group(P < 0.05).However,the experimental treatments did not significantly affect the Chao1,Simpson,and Shannon indices of cecal microbiota,but the combination of YSE and C.butyricum increased the beta-diversity of microbiota.At the microbial community level,Firmicutes and Bacteroidetes were the dominant phyla in the cecum of meat rabbits,and the addition of YSE and C.butyricum increased the abundance of Firmicutes while reducing the abundance of Bacteroidetes and Proteobacteria.At the genus level,the combined addition of YSE and C.butyricum notably increased the abundance of beneficial bacteria Ruminococcaceae and decreased the proportion of pathogenic bacteria such as Pseudomonadaceae and S24-7.Correlation analysis found that the abundance of Pseudomonadaceae_Pseudomonas,Ruminococcus,Lachnospiraceae Clostridium,and Allobaculum was positively correlated with TAC,while Shigella and Blautia levels were negatively correlated with TAC.The abundance of Lachnospiraceae Clostridium,Pseudomonadaceae_Pseudomonas,Blautia,and intestinal villus height was significantly positively correlated,while the abundance of Allobaculum and Shigella was negatively correlated with intestinal villus height(P < 0.05).The levels of Ruminococcus and Lachnospiraceae Clostridium were significantly negatively correlated with crypt depth(P < 0.05).In terms of intestinal metabolome,lipids and lipophilic molecules,organic heterocyclic compounds,organic acids,and derivatives,and phenylpropanoids and polyketides accounted for 16.74%,33.33%,16.46%,and 9.48%,respectively,of the intestinal metabolites of meat rabbits.The dietary addition of YSE and C.butyricum significantly affected the composition of intestinal metabolites.There were 51 different metabolites between the Ctrl group and the YSE + C.butyricum group,of which 36 were notably upregulated and 15 were significantly downregulated.A total of 15 affected KEGG metabolic pathways were enriched,with the most different metabolites enriched in glycerophospholipid metabolism and bile secretion,and the degree of enrichment in glycerophospholipid metabolism was most significant,where taurine and hypotaurine metabolism were the top enriched differential metabolic pathways in topological analysis.Collectively,the above results indicate that dietary supplementation with YSE and C.butyricum could increase the digestibility of nutrients in meat rabbits by promoting intestinal development,improving the composition of intestinal microbiota,and affecting changes in intestinal metabolites,thereby improving the growth performance of weaned rabbits.In addition,the addition of YSE and C.butyricum increased the antioxidant capacity and muscle quality of the body,and the combined use of yarrow extract and C.butyricum has a better effect than the utilizations of along YSE and C.butyricum.