Study On The Feeding Effect Of Lactobacillus Paracasei Added To The Diet On Laying Hens

The aim of this experiment was to investigate the effects of Lactobacillus paracasei in the diet on production performance,egg quality,serum biochemical indexes,immune antioxidant and inflammatory factors,intestinal digestive enzyme activity and cecum microbiota of laying hens,and to evaluate the suitable additive amount of Lactobacillus paracasei LK01 on laying hens.A total of 288 24-week-old brown hens were randomly divided into four groups:control group was fed the basal diet,group I was fed the basal diet+10~6CFU/kg Lactobacillus paracasei,group II was fed the basal diet+10~7CFU/kg Lactobacillus paracasei,and group III was fed the basal diet+10~8CFU/kg Lactobacillus paracasei.Each group had 4 replicates of18 animals each.The trial period was 60 days.The results showed that.(1)In terms of production performance,the average egg laying rate(P<0.05)was significantly higher in test group II(P<0.05)and test group III(P<0.05)than in the control group;the average egg weight(P<0.05)was significantly higher in all test groups than in the control group,among which test group III(P<0.05)was significantly higher than in all other treatment groups.The feed to egg rate was lower in all experimental groups compared with the control group,with the experimental groupⅢ(P<0.05)being significantly lower than the control group.(2)In terms of egg quality,there was a trend of improvement in Albumen height and Haugh unit in all experimental groups compared with the control group,among which groupⅢ(P<0.05)was significantly higher than the control group;there was a trend of improvement in mean egg weight in all experimental groups compared with the control group,among which groupⅢ(P<0.05)was significantly higher than the control group;the egg shell strength in groupⅠ(P<0.05)was significantly higher than the control group.(3)In terms of serum biochemical indexes,serum alanine aminotransferase(ALT)level was significantly higher in test groupⅢthan in the control group(P<0.05);serum total protein(TP)level was significantly higher in all test groups than in the control group(P<0.05);serum albumin(ALB)level was significantly higher in test groupⅡthan in the control group(P<0.05);serum aminotransferase(ALB)level was significantly higher in test groupⅢthan in the control group(P<0.05).ALB)levels were significantly higher in test groups II and III than in the control group and test group I(P<0.05);serum total cholesterol(TC)levels were significantly lower in test groups II and III than in the control group and test group I(P<0.05);serum triglyceride(TG)levels were significantly higher in the control group than in the test groups(P<0.05);serum triglyceride(TG)levels were significantly higher in the control group than in the test groups(P<0.05).The levels of serum phosphorus(P)were significantly higher in the test II group than in the control group(P<0.05);the levels of serum aminotransferase(AST),serum urea nitrogen(BUN),and serum calcium(Ca)were not significantly different among the treatment groups(P<0.05).levels were not significantly different(P>0.05).(4)In terms of serum immune and antioxidant indexes,the levels of total antioxidant capacity(T-AOC)were significantly higher than those of the control group(P<0.05);in terms of serum malondialdehyde(MDA),the levels in test groups II(P<0.05)and III(P<0.05)were significantly lower than those of the control group;the remaining indicators were not significantly different in the test group compared with the control group(P>0.05).(5)In terms of serum inflammatory factors,the addition of Lactobacillus paracasei to the diet had no significant effect on the serum interleukin-1β(IL-1β)level(P>0.05);in terms of serum interleukin-2(IL-2)level,the test groups were lower than the control group,among which the test groupsⅠandⅢwere significantly lower than the control group(P<0.05).In terms of serum interleukin-6(IL-6)levels,they were lower than those in the control group,with those in groups II and III being significantly lower than those in the control group(P<0.05),and those in group III being significantly lower than those in group I(P<0.05);in terms of serum macrophage Tumor Necrosis Factor-α(TNF-α)levels,they were lower than those in the control group.In terms of TNF-α,there was a tendency to decrease in all test groups,among which test groupⅢwas significantly lower than the control group(P<0.05).(6)In terms of intestinal enzyme activity,the differences in the levels of duodenal,jejunal and ileal digestive enzymes in each treatment group were not significant(P>0.05).(7)In terms of intestinal flora,at the phylum level,the phylum Bacillus mimicus and the phylum Thick-walled bacteria were the dominant bacteria,and the percentage of the phylum Helicobacter intestinalis was significantly reduced in all test groups(P<0.05).At the genus level,the phylum Synechococcus and the phylum Riebacteriaceae RC9 intestinal group were the core dominant bacteria,and the percentage of Clostridium genus was significantly reduced in testⅡgroup and testⅢgroup(P<0.05),and the percentage of dense spirochete genus was significantly reduced in all test groups(P<0.05).In conclusion,the addition of Lactobacillus paracasei to the diet could improve the production performance as well as the egg quality of laying hens,improve the serum biochemical indexes of laying hens to some extent,increase the antioxidant capacity of laying hens serum,reduce the expression of pro-inflammatory factors and inhibit the harmful intestinal flora of laying hens.In conclusion,the optimal supplemental concentration of Lactobacillus paracei was 10~8CFU/kg.