China Animal Husbandry and Veterinary Medicine ›› 2025, Vol. 52 ›› Issue (5): 2318-2327.doi: 10.16431/j.cnki.1671-7236.2025.05.035

• Basic Veterinary Medicine • Previous Articles    

Study on the Correlation Between β-lactase blaZ Gene and Microorganisms in Milk of Cows with Latent Mastitis in Shandong Region

LIU Zhixu1, HAN Wenchang1, LI Yanqin2, ZHANG Liwen3, LIU Yan3, YUAN Shaowei3, LIJianbin2, WANG Xiao2, CAO Rongfeng1   

  1. 1. College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China;
    2. Institute of Animal Husbandry and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan 250100, China;
    3. Shandong OX Livestock Breeding Co., Ltd., Jinan 250100, China
  • Received:2024-07-16 Published:2025-04-27

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Abstract: 【Objective】 This study aimed to explore the relationship between β-lactase blaZ gene and microorganisms in milk of cows with latent mastitis in Shandong region,and provide theoretical basis for preventing and controlling latent mastitis in cows and reduce antibiotic resistance genes in raw milk.【Method】 From February to June 2023,478 milk samples from 478 cows randomly selected from 33 dairy farms in 15 cities were tested for the β-lactase blaZ gene and 15 microbial genes using PCR method.Heatmap of the relative abundance of blaZ genes and microorganisms based on the pheatmap function in R language was drew,Logistic regression fitting was performed using the glm function in R language.The above scheme was repeated with 506 milk samples from 506 cows with latent mastitis in 5 cities of Shandong province.【Result】 The positive rate of blaZ gene in randomly obtained milk samples from 15 cities in Shandong province was 19.25%,with a high positive rate in small ranches.The relative abundance of coagulase-negative Staphylococcus,yeast and Enterococcus spp.in milk was relatively high,and they were positively correlated with the blaZ gene (P＜0.01 or P＜0.05).blaZ gene was only negatively correlated with the relatively low abundance of Klebsiella spp.(P＜0.05).The positive rate of blaZ gene in milk of cows with latent mastitis was 52.17%.The relative abundance of yeast,Enterococcus spp.and coagulase-negative Staphylococcus in milk was relatively high.The blaZ gene was only positively correlated with coagulase-negative Staphylococcus (P＜0.01) and negatively correlated with Streptococcus uberis (P＜0.01).【Conclusion】 The expression level of blaZ gene in milk with latent mastitis in Shandong region was higher than that in randomly sampled milk. In milk from Shandong region, blaZ gene mainly originated from coagulase negative Staphylococcus aureus, which was also the main pathogenic bacterium causing latent mastitis in the region.

Key words: latent mastitis in dairy cows; β-lactase blaZ gene; Logistic regression; microbial abundance

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