Acta Veterinaria et Zootechnica Sinica ›› 2025, Vol. 56 ›› Issue (12): 6351-6363.doi: 10.11843/j.issn.0366-6964.2025.12.037

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Isolation and Identification of a Chicken Source Bacillus subtilis Strain and Its Protective Effect on Diarrhea in Chicks

LÜ Ziyi1, ZHANG Xinbo1, WANG Hongzhi2, GUO Honglei1, ZHAO Chunxu1, LIU Shunbo1, MA Ning1*   

  1. 1. College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China;
    2. Hebei Functional Feed Additive Technology Innovation Center, Hebei Institute of Traditional Chinese Veterinary Medicine Industry Technology, Shijiazhuang 050000, China
  • Received:2024-07-26 Online:2025-12-23 Published:2025-12-24

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Abstract: This experiment mainly carried on isolation and identification Bacillus subtilis (B.S) from healthy egg chicken fecal samples, and explored the protective effect on E.coli O78 induced diarrhea in chicks. The experiment used morphological identification and 16S rDNA sequencing to isolate, screen and identify B.S. The tolerance to pH, bile salts, and artificial gastrointestinal fluids and hemolysis was assessed. Ninty-six healthy 1-day-old Dawu Jinfeng laying hens were selected for animal experiments and randomly divided into eight groups, 12 chickens per group: The control group (fed with basal diet, CON), low dose group (fed with basal diet and orally administeres 1 mL×109 CFU of B.S JZH 9, LBS), medium dose group (fed with basal diet and orally administeres 1 mL×1010 CFU of B.S JZH 9, MBS), and high dose group (fed with basal diet and orally administeres 1 mL×1011 CFU of B.S JZH 9, HBS). The model group (fed with basal diet and orally administered 1 mL×4.5×1012 CFU of E.coli O78, Model), low dose prevention group (LBS + E.coli), medium dose prevention group (MBS + E.coli), and high dose prevention group (HBS + E.coli). The study analyzed the effects of the B.S JZH 9 on the growth performance and intestinal health of E.coli O78 challenged laying chicks. The experiment lasted for 21 days, with oral administration of B.S JZH 9 fod 1~18 days and oral administration of E.coli O78 for 19~21 days. The results showed that the isolated Gram-positive bacteria, identified as B.S by 16S rDNA, named B.S JZH 9. With the characteristics of acid and bile salt resistance, no hemolytic reaction, and tolerance to artificial gastrointestinal fluids. The results of animal testing showed that compared with the CON, the LBS, MBS, HBS had no significant effect on average daily gain (ADG), average daily feed intake (ADFI), and feed conversion rate (FCR) from 1 to 21 days. Compared with the Model, the LBS + E.coli showed a trend of reducing FCR from 1 to 21 days and the LBS + E.coli, MBS + E.coli and HBS + E.coli significantly increased the villus height and villus-crypt ratio, while the MBS + E.coli and HBS + E.coli significantly reduced the crypt depth of duodenal. Compared with the CON, the content of E.coli was significantly increased in the jejunum of the Model, while feed different concentrations of B.S JZH 9 reduced the relative content of E.coli to varying degrees. In summary, B.S JZH 9 isolated from the feces of healthy laying hens, promoted growth performance, increased the villus height and villus-crypt ratio of small intestinal, reduced crypt depth, increased the absorption area of the small intestine, and reduced the content of E.coli in the jejunum, thereby regulating intestinal health and slowing down the damage caused by E.coli O78 to the intestine.

Key words: Bacillus subtilis, laying hen, growth properties, intestinal health

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