Considering potential roles of selected MicroRNAs in evaluating subclinical mastitis and Milk quality in California mastitis test (+) and infected bovine milk

Abstract

AbstractThis study investigates the relationships between subclinical mastitis and milk quality with selected microRNAs in cow milk. California Mastitis Test (CMT)‐positive (n = 20) and negative (n = 20) samples were compared (Experiment I). Additionally, samples with CMT‐positive but microbiological‐negative, as well as positive for only Staphylococcus subspecies (Staph spp.) and only Streptococcus subspecies (Strep spp.) were examined (Experiment II). Four groups were formed in Experiment II: Group I (CMT and microbiological‐negative) (n = 20), Group II (CMT‐positive but microbiological‐negative) (n = 10), Group III (Staph spp.) (n = 5), Group IV (Strep spp.) (n = 5). While electrical conductivity, somatic cell count (SCC), malondialdehyde (MDA) increased, miR‐27a‐3p and miR‐223 upregulated and miR‐125b downregulated in the CMT‐positive group in Experiment I. SCC and MDA were higher in CMT‐positive groups. miR‐27a‐3p and miR‐223 upregulated in Groups III and IV. While miR‐155 is upregulated, miR‐125b downregulated in Group IV. Milk fat is positively correlated with miR‐148a and miR‐223. As miR‐27a‐3p positively correlated with SCC and MDA, miR‐125b negatively correlated with electrical conductivity and SCC. miR‐148a and MDA were positively correlated. miR‐155 was correlated with fat‐free dry matter, protein, lactose, and freezing point. miR‐223 was positively correlated with SCC and miR‐148a. Results particularly highlight miR‐27a‐3p and miR‐223 as potential biomarkers in subclinical mastitis, especially those caused by Staph spp. and Strep spp., while miR‐148a, miR‐155, and miR‐223 stand out in determining milk quality.