| In this experiment,the effects of yeast engineering bacteria containing antibacterial peptide Cec Md,3cs and 3js on growth performance,nutrient metabolism rate,slaughter performance,blood biochemical index,intestinal flora and immune function of broilers at different growth stages were studied.The experiment was conducted with a single factor complete randomized design,400 healthy 1-day-old arbor acres broilers were randomly divided into 5 groups.Two control groups were designed in the experiment: the blank control group and antibiotic group,three experimental groups were added Cec Md,3cs and 3js in leased died.There were 4replicates in each group and 20 chickens in each replicate(male and female).The blank control group drank normal water,in the antibiotic group,50 mg/d of Tylosin was added to the diet,and 8 mg/L of yeast engineering bacteria containing Cec Md,3cs and 3js were added to the water fed also.During period 1~6 weeks,and the daily gain and ever age daily feed intake of broilers were measured every week.Metabolic tests were carried out at 3 weeks and 6 weeks of age,respectively,and Slaughter test was carried out according to the age of week,serum and chyme was collected.Production performance,slaughter performance,metabolic rate of nutrients,serum biochemical index,intestinal microorganism and immune index of broilers were analyzed.The results showed that:(1)The daily gain was significantly increased by the yeasts with Cec Md and 3js in 3wks,and increased by 9.12% and 8.72% compared with the control group(P<0.05),the daily intake was significantly increased by the yeasts with Cec Md and 3cs in 3wks,and increased by 7.59%and 8.23% compared with the control group(P<0.05).The daily gain and daily intake were significantly increased and the feed/gain was significantly decreased by the yeast with Cec Md,3cs and 3js in 6 wk(P<0.05).The metabolic rate of ADF significantly increased for chickens fed yeasts with 3cs in 3wk(P<0.05),the metabolic rate of CP significantly increased by yeasts with Cec Md and 3cs in 6wk(P<0.05).(2)The slaughter weight,semi-net weight,semi-net rate,total net rate in 3wks and total net rate in 6wks were significantly increased for chickens fed yeasts with 3cs(P<0.05),which were increased by 4.74%,18.57%,11.94%,10.04% and 3.30% compared with the controlrespectively,the chest muscle weight and legs muscle weight in 3wks and semi-net rate in 6wks were significantly increased for chickens fed yeasts with Cec Md,3cs,and 3js(P<0.05),the total net weight was significantly increased by the yeasts with Cec Md and 3cs in 3wks(P<0.05),the slaughter weight,chest muscle weight,semi-net weight,total net weight,and slaughter rate,chest muscle rate were significantly increased by the yeasts with Cec Md in 6wks(P<0.05),the yeasts with 3js also increased the chest muscle weight,semi-net weight and total net weight in6wks(P<0.05).(3)The serum total protein content was significantly increased by the yeasts with 3js in2wks(P<0.05).The serum albumin content significantly increased in 2wks and the serum alanine aminotransferase content reduced in the 1wk,2wks and 4wks for chickens ate the yeasts with Cec Md and 3cs(P<0.05).Beside 3wks during the yeasts with Cec Md and 3js that chickens were fed reduced serum urea nitrogen levels in the 1wk,2wks,4wks,5wks and 6eks,and chickens fed 3cs also decreased serum urea nitrogen levels in 2wks(P<0.05),the alanine aminotransferase content significantly decreased by the yeasts with Cec Md,3cs and 3js in 2wks and by the yeasts with Cec Md in 5wks(P<0.05).(4)The number of Escherichia coli in the 1wk,4wks and 5wks and the number of Salmonella from the 2wks to 6wks were significantly reduced for chickens ate the yeasts with Cec Md(P<0.05),the number of Escherichia coli in 3wks and 5wks and Salmonella from 2wks to 6wks declined significantly for feeding the yeasts with 3cs(P<0.05),the number of Escherichia coli in the third week and the number of Salmonella from 2wks to 4wks were significantly declined for chickens fed the yeasts with 3js(P<0.05).The number of lactobacilli from 4wks to 6wks and the number of Bifidobacterium in 2wks,3wks,5wks and 6wks were significantly increased by the yeasts with Cec Md(P<0.05),the number of Lactobacillus in5 wks and Bifidobacterium in 5wks and 6wks were significantly increased by the yeasts with 3cs(P<0.05).the number of Bifidobacterium in 5wks and Bifidobacterium in 3wks to 6wks were significantly increased by the yeasts with 3js(P<0.05).(5)The thymus index in 3wks to 6wks,the spleen index in the 1wk to 6wks and the bursal index from 3wks to 6wks were significantly increased by the yeasts with Cec Md(P<0.05),the thymus index in 3wks and 5wks,the spleen index from 2wks to 6wks and the bursal index from4 wks to 6wks were significantly increased by the yeasts with 3cs(P<0.05),the thymus index inthe 2wks,5wks and 6wks,the spleen index in the 4wks to 6wks were significantly increased by the yeasts with 3js(P<0.05).The IgA content in 3wks and 5wks,the IgG content in 3wks and the IgE content in 4wks and 5wks were significantly increased by the yeast with Cec Md(P<0.05),the IgA content was significantly increased by the yeasts with 3cs and 3js in 6wks(P<0.05),the IgG content in 3wks and the IgM content in the 1wk were significantly increased by the yeasts with 3js(P<0.05).To sum up,the daily gain,daily intake and feed/weight were increased by the yeast engineering bacteria containing Cec Md,3cs and 3js of broilers at different growth stages,and the slaughter weight,semi-net rate,total net rate were increased of broilers.The contents of BUN and ALT in the blood of broilers were decreased and the growth of harmful bacteria in intestinal tract of broilers was inhibited,which promoted the increase of beneficial microflora,but had little effect on the metabolic rate of nutrients,the contents of TP,Alb and immunoglobulin in blood of broilers. |
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