Effects Of Dietary Probiotics For The Brooding Period On The Growth Performance,Intestinal Health,and Subsequent Production Performance Of Laying Hens

This experiment was conducted to investigate the effects of dietary Bacillus subtilis(BS)and Enterococcus faecium(EF)on the growth performance,intestinal health and laying performance of laying hens,and to explore the application effect of probiotics in the early stage of laying hens.A total of 528 Lohmann laying hens aged 1-day-old were assigned in a 2×2 factorial design,which encompassed 2 dietary levels of BS(0 or 6×10~6CFU/g)and 2 dietary levels of EF(0 or 4×10~5CFU/g)in 6 replications,and 22 birds per replication for 30 wk.The experimental treatment was conducted from week 1 to 8,and all groups were fed basic feed without probiotic treatment from week 9 to 30.The results showed that:1)BS supplementation from 1 to 8 weeks significantly decreased F/G and average feed intake of laying hens from 1 to 8 weeks(AFI,P<0.05),and tended to increase average body weight gain(BWG)from 9 to 20 weeks(P=0.054).EF supplementation at 1-8 weeks significantly increased F/G at 1-8 weeks(P<0.05),tended to decrease average body weight at 8 weeks(P=0.067),BWG at 1-8 weeks(P=0.067),and significantly decreased AFI at 9-20 weeks(P<0.05).2)The addition of BS from 1 to 8 weeks tended to increase the content of growth hormone(GH,P=0.057)and growth hormone receptor(GHR,P=0.078)in serum at 8weeks.EF supplementation from 1 to 8 weeks significantly increased the content of serum GHR and insulin-like growth factor-1 at 8 weeks(P<0.05).The addition of BS and EF at1-8 weeks had a significant interaction effect on serum growth related hormones at 8weeks(P<0.05),and the combined addition significantly increased serum GH and GHR contents(P<0.05).3)The serum anti-Mullerian hormone(AMH)content at 20 weeks was increased by BS supplementation from 1 to 8 weeks(P=0.058).EF supplementation at 1-8 weeks significantly increased the contents of serum estradiol,follicle-stimulating hormone and progesterone at 20 weeks(P<0.05).There was a significant interaction between BS and EF supplementation at 1-8 weeks on the serum AMH content at 20 weeks(P<0.05),and the combined supplementation significantly reduced the serum AMH content at 20 weeks(P<0.05).4)The addition of BS at 1-8 weeks significantly decreased the contents of serum ALP,LDL-C and TC at 8 weeks(P<0.05),and tended to decrease the content of serum ALT at 8weeks(P=0.068).EF supplementation from 1 to 8 weeks significantly increased the content of serum ALB at 8 weeks(P<0.05),and decreased the content of serum ALT at 8weeks(P<0.05).The addition of BS and EF at 1-8 weeks had an interaction effect on serum ALB at 8 weeks,and the combined addition significantly increased serum ALB content(P<0.05).5)The addition of BS at 1-8 weeks significantly increased the villus/CD ratio(VH/CD,P<0.05)in ileum at 8 weeks,and tended to increase the villus length(VH)in jejunum at 8weeks(P=0.085).The effect of BS supplementation from 1 to 8 weeks significantly decreased the crypt depth of ileum at 20 weeks(CD,P<0.05),and tended to decrease the duodenal CD(P=0.058)and ileal VH(P=0.068)at 20 weeks.The relative length of duodenum(P=0.066)and relative weight of ileum(P=0.091)at 8 weeks were decreased by EF supplementation from 1 to 8 weeks.The addition of BS and EF at 1-8 weeks had an interaction effect on ileal morphology at 8 weeks,and the combination of BS and EF significantly decreased ileal VH and VH/CD(P<0.05).6)The addition of BS from 1-8 weeks significantly increased the relative abundance of Bacteroidetes(P<0.05),and significantly decreased the relative abundance of Proteobacteria and Cyanobacteria(P<0.05)at the phylum level of 8 weeks.The effect of BS supplementation from 1 to 8 weeks significantly reduced the relative abundance of Desulfobacterota at the 20-week phylum level(P<0.05).EF supplementation from 1 to 8weeks significantly increased Proteobacteria at 8 weeks(P<0.05),and tended to increase the relative abundance of Cyanobacteria(P=0.099).The addition of BS and EF from 1-8weeks significantly increased the relative abundance of Alistipes at the genus level at 8weeks(P<0.05).The addition of EF at 1-8 weeks tended to increase the relative abundance of Lactobacillus at the genus level at 8 weeks(P=0.061).There was a tendency to decrease the relative abundance of Barnesiella(P=0.085)and Clostridia＿vadin BB60＿group(P=0.094).The addition of BS and EF at 1-8 weeks had an interaction effect on the genus level at 20 weeks,and the combined addition significantly increased the relative abundance of Methanobrevibacter(P<0.05).7)The addition of BS at 1-8 weeks significantly increased the content of serum immunoglobulin A(Ig A)at 8 weeks(P<0.05).The effect of BS supplementation from 1 to8 weeks significantly increased the contents of Ig G and Ig M in serum at 20 weeks(P<0.05).EF supplementation significantly increased the contents of serum immunoglobulin G(Ig G)and immunoglobulin M(Ig M)at 8 weeks(P<0.05),and tended to increase the content of Ig A(P=0.054).The contents of Ig A,Ig G and Ig M in serum at week 20 were significantly increased after the addition of EF from week 1 to week 8(P<0.05).The addition of BS and EF at 1-8 weeks had a significant interaction effect on serum Ig A at 20 weeks,and the combined addition significantly increased the content of serum Ig A(P<0.05).8)The addition of BS from 1 to 8 weeks tended to increase the average daily feed intake(ADFI,P=0.080)from 21 to 30 weeks,eggshell weight(P=0.071)from 25 weeks and eggshell thickness(P=0.091)from 30 weeks.Compared with the group without probiotics,the egg production rate of the BS group increased by 2.27%at 21-30 weeks(P>0.05).EF supplementation from 1 to 8 weeks significantly decreased ADFI and average egg weight of laying hens from 21 to 25 weeks(P<0.05),and tended to reduce laying rate from 21 to 25 weeks(P=0.094).In conclusion,dietary BS during brooding period can improve intestinal flora,promote the propagation of beneficial bacteria,improve intestinal morphology,maintain intestinal health and improve the immune level,and its effect can last until laying period to improve performance during laying period,which is better than EF and the combined addition of the two strains.