Effects of Different Concentrations ofHomologous Probiotics on Small lntestinal Mucosa Structure of 42-day-old Broilers

Yuxian ZHANG，Wenli WANG，Yaoxing CHEN，Zixu WANG，Jing CAO

1.Department of Husbandry and Veterinary，Beijing Vocational College of Agriculture，Beijing 102442，China；

2.College of Veterinary Medicine，China Agricultural University，Beijing 100193，China

Effects of Different Concentrations of
Homologous Probiotics on Small lntestinal Mucosa Structure of 42-day-old Broilers

Yuxian ZHANG1，Wenli WANG1，Yaoxing CHEN2*，Zixu WANG2，Jing CAO2

1.Department of Husbandry and Veterinary，Beijing Vocational College of Agriculture，Beijing 102442，China；

2.College of Veterinary Medicine，China Agricultural University，Beijing 100193，China

In the study，the methods of applied histology and histochemistry were used to determine intestinal villus length，crypt depth，the ratio of intestinal villus length to crypt depth，mucous membrane thickness and intestinal wall thickness of duodenum，jejunum and ileum of 42-day-old broilers，so as to study the effects of different concentrations of homologous probiotics on small intestinal mucosa structure of the broilers.The results showed that the effect of 0.3%probiotics on small intestine mucosal structures was the best，such as the length of intestinal villus was the longest，the ratio of villus length to crypt depth was the largest，the thickness of mucous membrane and intestinal wall was the thickest.These showed that 0.3% probiotics had best effect on improving and enhancing the digestion-absorption function of the small intestine of the broilers.

Broiler；Homologous probiotics；Small intestine；Mucosal structure

H omologous probiotics is a kind ofactive microbialadditive separated from the intestinal tract of the broilers.The research showed that probiotics can develop and breed in the intestinal tract and play a beneficial effect after ingesting by the livestock，thereby promoting the growth of the livestock，improving the efficiency of feed utilization，avoiding diarrhea and improving the disease resistance of the body，thus it is a widely applied and multifunctional green feed additive［1］.Probiotics has the merits of non-pollution，strong resistance to disease，high safety，nontolerance，no residue and low cost，etc.，moreover，it can not generate“three reactions”to human beings and animals，thus it can replace antibiotics and be widely applied in animal husbandry［1］.

Small intestine not only is the important place of nutrient substance digestion and absorption，but also has important immunologic barrier function.Good small intestinal mucosa structure is the physiological basis of the digestion and absorption of nutrient substance and the regular growth of animals［2-4］.In this study，different dosages of probiotics were added to the fodder of the broilers，so as to study the optimum concentration which has promoting effect to small intestinal mucosa structure of the broilers，thereby providing some reference and bases for the application of probiotics in the feeding of the broilers.

Materials and Methods

Experimental animal and grouping

The experimental animals were 1 500 one-day-old AA broilers（there were both cocks and hens，the average weight was about（42.90±0.26）g，and they were provided by Beijing Huadu Broiler Corporation）and were randomly divide into 5 groups，the control group was fed with full-pricebasic ration，groups 1，2，3 and 4 were respectively added with 0.1%，0.2%，0.3%and 0.4%homologous probiotics based on basic ration，each group had 10 repetitions，and each repetition had 30 broilers.The experimental period was 42 d.

Feeding and management

Maize-bean pulp was taken as basic ration，the nutritional ingredient was prepared according to the standard of NRC nutrition requirements for poultry （in 1994）.The feeding and management was based on the management regulations of broilers of Beijing local standard DB23/T169-93.The routine immunization was based on the immune procedure formulated by localepidemic prevention departments.

The source of homologous probiotics

The bacteria of homologous probiotics was screened out from the intestinal tract of the broilers，modern fermentation technology was adopted for purifying，and the corresponding carriers，which included multiple probiotics，such as Bacillus，lactic acid bacteria，Bifidobacterium，etc.，were matched，the product was brown powder，and the viable count was 20×108cfu/g.

Sample treatment

At the 42thd of the experiment，there were 5 broilers killed in each group，2-3 mm middle pieces respectively from duodenum，jejunum and ileum were got quickly，then they were dipped into the new allocative normal saline and rinsed the restricted substance，after that，40 g/L paraformaldehyde phosphate buffer（0.1 mol/L，pH 7.4）was used for fixing for 48 h，then embedded in the paraffin to prepare 10 continuous cross sectional slices（the thickness was 5 μm），conventional hematoxylin-eosin （H.E.）was used for dyeing.

Measuring items

The indexes of growth performance The broilers were weighed and recorded at the beginning and at the end ofthe experiment，the feed consumption wasdetermined and recorded.

Histological indexes After H.E. dye，the smallintestinalmucosa structure was observed under the light microscope.5 slices from each small intestine were got，and 2-5 views from each slice were selected，Moditec processing software was used to take photos，each photograph contained 5 lengths of the longest intestinal villi（from the joint of intestinal villi to the top of villi），the deepest crypt depth（from the joint of intestinal villi to the base of enteraden），the thickness of mucous membrane，the thickness of intestinal wall and the ratio of villus length to crypt depth（V/C）.

SPSS17.0 statistical software was adopted to carry out one-way analysis of variance and multiple comparisons on the determination data.

Results and Analyses

The change of the weight

As seen in Table 1，it can be shown that the birth weights of the broilers of each group had not differences（P＞0.05）；42 d after feeding，the final weights，daily gain and daily feed intake of 4 experimental groups increased compared with CK，but the feed/gain ratio all decreased；for daily gain，0.3%group had extremely significant differences with other groups（P＜0.01）；for daily feed intake，there was not difference among 5 experimental groups（P＞0.05）；for feed/gain ratio，0.3%group had significant differences with other groups （P＜0.01）；this showed that the feed intake of 0.3%group was less，the weight increment was quicker and the feed conversion ratio was higher.

The change of morphological structure of intestinal mucosal epithelium

After H.E.dye，the intestinal mucosa structure was observed under the light microscope and found that the intestinalmucosa structures of5 groups of the broilers all had complete and well arranged structures，the epithelial cell of intestinal mucosa had clear outline，bright dye and regular arrangement，the top of intestinal villi had not obscission.

The changes ofintestinalvillus length，mucous membrane thickness，intestinal wall thickness and the ratio of villus length to crypt depth （in Table 2-Table 4，Fig.1-Fig.3）

From Fig.1-Fig.3，it can be seen that for the intestinal villi of 42-day-old broilers from duodenum and jejunum to ileum，the intestinal villus length，intestinal wall thickness and villus length gradually reduced.From Table 2，it can be drawn that intestinal villus length，mucous membrane thickness，intestinal wall thickness and the ratio of villus length to crypt depth（V/C value）of duodenum of 0.3%group were all superior to these of other groups. From Table 4，it can be seen that the indexes of mucosal structure of ileum of 0.3%group were all higher than these of CK，0.2%group and 0.4% group；for intestinal villus length and crypt depth of ileum，0.3%group was higher than other groups.These indicated that adding 0.3%probiotics in broiler feed was the best.

Discussions and Analyses

Effects of different dosages of homologous probiotics on weight gain of the broilers

In this experiment，the probiotics was beneficial bacteria extracted from the intestinal tract of the broilers，such as Bacillus，lactic acid bacteria and Bifidobacterium，etc.，in which Bacillus is an aerobe，which provides an anoxic growing environment for lactic acid bacteria，and at the same time，it translates the starch into monosaccharide for lactic acid bacteria［5］.Hua Jing et al. showed that Bacillus subtilis can promote the anabolism of the protein and the lipid in the body of the broilers，promote the growth and development of skeleton and muscle，thereby benefiting to promote the growth of animals. The experimental results showed that adding 0.1%，0.2%，0.3%and 0.4% homologous probiotics in broiler feed can improve weight increment and the efficiency of feed utilization of the broilers，and reduce feed/gain ratio，but the concentration of 0.3%had the best efficiency and achieved the highest economic benefit.

Effects of different dosages of homologous probiotics on small intestine mucosal structures of the broilers

The normal structure and function of small intestine is the basic guarantee of the sufficient digestion and absorption of nutrient substance，especially，the intestinalvillus length，crypt depth， mucous membrane thickness and superficial area of villus are important indexes measuring the digestion-absorption function of small intestine［4-6］.The experimental results showed that the intestinal mucosa structures of 5 groups of the broilers all had complete and well arranged structures，the epithelial cell of intestinal mucosa had clear outline，bright dye and regular arrangement，intestinal villi had not obscission，especially the top of intestinal villi.After adding the probiotics in broiler feed， the height of intestinal villi of duodenum，jejunum and ileum showed dosedependentgrowth，moreover，the height of intestinal villi of probiotics group was higher than that of CK. Hereinto，the villus height，the thickness of intestinal mucosa and in-testinal wall thickness of duodenum，jejunum and ileum of the broilers in 0.3%group were all higher than these of CK，the villus height of duodenum had extremely significant difference with that of CK （P＜0.01），and that of jejunum had significant difference with that of CK （P＜0.05），however，that of ileum had not significant difference with that of CK （P＞0.05）.The ratio of the length of intestinal villi to crypt depth in duodenum showed dose-dependent growth，moreover，the ratio of 0.3%group was significantly higher than that of CK （P＞0.05）.The research of physiology of nutrition also showed that the ratio of the length of intestinal villi to crypt depth comprehensively reflected the function of small intestine，the decline of the ratio showed the decrease of digestionabsorption function［7］，therefore，the growth and development of animals was inhibited.This experimental results showed that probiotics had effect on the digestion and absorption of small intestine.Different concentrations of probiotics all can enhance the digestion-absorption ability of small intestine of the broilers and make the growth and development of the broilers quicken，what’s more，0.3%concentration of probiotics was the best，and can perfect and maintain the normal structure of small intestine mucosa of the broilers，improve the digestion-absorption ability of small intestine of the broilers，moreover，its daily gain was the most obvious，the feed consumption was the least，the growth and developmentwasthe quickest，feed/gain ratio was the lowest and the economic benefit was the highest.

Table 1 Effect of homologous probiotics on the weight of the broilers

Table 2 Effects of different concentrations of homologous probiotics on intestinal villus length，mucous membrane thickness，intestinal wall thickness and the ratio of villus length to crypt depth of duodenum of 42-day-old broilers

Table 3 Effects of different concentrations of homologous probiotics on intestinal villus length，mucous membrane thickness，intestinal wall thickness and the ratio of villus length to crypt depth of jejunum of 42-day-old broilers

Table 4 Effects of different concentrations of homologous probiotics on intestinal villus length，mucous membrane thickness，intestinal wall thickness and the ratio of villus length to crypt depth of ileum of 42-day-old broilers

Conclusions

（1）Different concentrations of homologous probiotics were added into the basic ration of the broilers；from the analysis results of weight increment，feed consumption，feed/gain ratio，feed conversion and economic benefit，adding 0.3%probiotics had best efficiency.

（2）From small intestine mucosal structures of 42-day-old broilers of view，the broilers of 0.3%group had the most gain weight，the largest indexes like intestinal villi length and crypt depth，etc.，and the strongest digestion-absorption ability；therefore，0.3% additive amount was the most reasonable for promoting the growth of the broilers.

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Responsible editor：Nanling WANG

Responsible proofreader：Xiaoyan WU

不同浓度的同源益生素对42日龄肉鸡小肠黏膜结构的影响

张玉仙1，王文利1，陈耀星2*，王子旭2，曹静2
（1．北京农业职业学院畜牧兽医系，北京102442；2．中国农业大学动物医学院，北京100193）

为了研究不同剂量的益生素对肉仔鸡小肠黏膜结构的影响，试验采用应用组织学和组织化学方法，测定了42日龄肉鸡十二指肠、空场、回肠的绒毛长度、隐窝深度、绒毛长度与隐窝深度比值、黏膜厚度和肠壁厚度等。结果表明：0．3%益生素对肉鸡小肠黏膜结构的影响最佳，肠绒毛长度最长，绒毛长度/隐窝深度比值最大，黏膜厚度和肠壁厚度最厚。说明0．3%益生素对改善和增强肉鸡小肠的消化吸收功能效果最好。

肉鸡；同源益生素；小肠；黏膜结构

北京农业职业学院院级项目（XYYF-14-18；XY-YF-14-16）。

张玉仙（1971－），女，北京通州人，副教授，硕士，研究方向动物药理和组织学，E-mail：185266201@qq．com．*通讯作者，教授，博士，博士生导师，研究方向为动物解剖与组织学，E-mail：yxchen@cau.edu.cn。

2015-06-13

Supported by the Project of Beijing Vocational College of Agriculture（XY-YF-14-18；XYYF-14-16）.

*Corresponding author.E-mail:yxchen@cau.edu.cn

Received:June 13，2015 Accepted:November 28，2015

修回日期 2015-11-28