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Simple Summary: Mastitis is a costly disease in dairy animals and significantly affects milk quality and quantity. The milk somatic cell count (SCC) is an acceptable method for diagnosing intramammary infections and evaluating the quality of milk. Mastitis is a multifactorial disease augmented by poor farm hygiene and milking practices. Therefore, the aim of the present study was to understand dairy farmers' knowledge about mastitis control, farm hygiene, milking practices, teat dipping, milk quality, milk SCC, the total bacterial count, social responsibility, etc., and its association with the bulk tank SCC using a structured questionnaire. The socioeconomic profiles, attitudes, and knowledge of farm managers from 63 dairy farms were analyzed. It was concluded that various parameters, such as the economic impact of mastitis, milking procedures, methods for subclinical mastitis detection, the awareness of the legal requirements of the SCC, and the total bacterial count (TBC), were associated with the SCC in bulk tank milk of dairy herds. The primary objective of this study was to investigate the association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and their socioeconomic characteristics. Additionally, we estimated the association between the bulk tank SCC and bulk tank milk hygienic quality in dairy herds. Bulk tank milk samples from 120 dairy herds enrolled in the milk quality payment program were collected for the determination of the SCC, the total bacterial count (TBC), the preliminary incubation count (PIC), the laboratory pasteurization count (PC), and the coliform count (CC). Based on the bulk tank SCC results, 63 herds were selected and categorized into three groups: (a) low SCC: ≤250,000 cells/mL (n = 16); (b) medium SCC: >250,000 ≤ 400,000 cells/mL (n = 24); and (c) high SCC: >400,000 cells/mL (n = 23). Socioeconomic profiles, attitudes, and knowledge of somatic cell count and milk quality were assessed using previously tested questionnaires, which were used to interview the herd managers of the 63 selected dairy herds. Among the findings, 87.0% of the dairy herds had an SCC < 400 × 103 cells/mL, and presented milk production as the main economic activity of the farm, whereas only 47.0% of dairy herds with an SCC > 400 × 103 cells/mL had milk production as the main economic activity of the farm (p < 0.031). In a total of 95% of the selected herds (n = 60), milking machines were used, with pipeline milking machines being more predominant, accounting for 70.8% in herds with a medium somatic cell count (SCC) and 78.3% in herds with a high SCC, as opposed to herds with a low SCC at 50% (p < 0.031). The frequency of dairy producers' awareness of the maximum legal requirements for the bulk tank SCC and TBC was higher in herds with a higher SCC than in herds with a medium SCC. In conclusion, the results of this study indicate a significant association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and socioeconomic characteristics. These findings emphasize the importance of knowledge and the socioeconomic profiles of dairy farms in maintaining and enhancing milk quality in dairy herds. [ABSTRACT FROM AUTHOR]

Prototheca spp. is a frequent cause of bovine mastitis and is highly resistant to commonly used disinfectants. This study aimed to: (1) evaluate the antimicrobial activity of polyhexamethylene biguanide (PHMB) against mastitis-causing Prototheca spp., and (2) evaluate the biofilm production ability of Prototheca spp. A total of 85 Prototheca bovis and 2 Prototheca blaschkeae isolates from bovine mastitis cases were submitted to biofilm production assays and antimicrobial susceptibility tests against PHMB and disinfectants commonly used in dairy herds (chlorhexidine digluconate, povidone-iodine, sodium dichloroisocyanurate, and sodium hypochlorite). The minimal inhibitory concentration (MIC) and minimal algicidal concentration (MAC) were determined by microdilution assays. We observed that PHMB (MIC 90 : ≥2 µg/mL and MAC 90 : ≥4 µg/mL) and chlorhexidine gluconate (MIC 90 and MAC 90 : ≥2 µg/mL) presented the highest antimicrobial activity against P. bovis isolates, followed by sodium dichloroisocyanurate (MIC 90 and MAC 90 : ≥1,400 µg/mL), sodium hypochlorite (MIC 90 and MAC 90 : ≥2,800 µg/mL), and povidone-iodine (MIC 90 and MAC 90 : ≥3,200 µg/mL). Concerning P. blaschkeae isolates, PHMB (MIC and MAC ≥1 µg/mL) and chlorhexidine gluconate (MIC and MAC ≥1 µg/mL) were the disinfectants that presented the lowest concentration values required to inhibit the isolates. Regarding biofilms formation, 63.5% (n = 54/85) of the P. bovis isolates were classified as strong, 28.3% (n = 24/85) moderate, and 8.2% (n = 7/85) weak biofilm producers. In contrast, the P. blaschkeae isolates were classified as weak and moderate biofilm producers. These findings suggest that PHMB has the potential to be used for teat and milking-equipment disinfection for the prevention of mastitis-causing Prototheca spp. in dairy herds. [ABSTRACT FROM AUTHOR]

Simple Summary: Prototheca algae are among the primary agents of bovine mastitis, incurring significant losses to the dairy industry related to a decrease in milk quality and yield, premature culling, and early replacement of infected cows. To date, there is no effective therapy for bovine mammary protothecosis. Here, the in vitro algaecide activity of quaternary ammonium (QA), a sanitizer used for animal and human purposes, was observed in Prototheca algae isolated from mastitic cows, indicating the potential use of this compound as an antiseptic/disinfectant for milking facilities and surrounding environmental areas. The in vitro algaecide activity of quaternary ammonium (QA) against Prototheca isolated from bovine clinical mastitis was investigated, in which the clinical severity was scored, milk samples were subjected to microbiological culture, and algal species were identified by molecular typing. A total of 4275 milk clinical samples of different cows from ten large dairy farms were used. Forty-four (1%) samples of cows from three dairy farms yielded growth of Prototheca, of which 88.6% (39/44) were identified as Prototheca bovis and 11.3% (5/44) as Prototheca sp. by MALDI-TOF MS, whereas 100% of the isolates were identified as P. bovis using PCR sequencing of the cytb gene. Among cows for which clinical severity scoring was available, 78.8% (26/33) and 21.2% (7/33) had mild and moderate infections, respectively, whereas no animal showed severe clinical signs. The algaecide activity of QA in Prototheca was observed in low concentrations among all isolates, in 20.4% (9/44) at 35 ppm, 36.4% (16/44) at 17 ppm, and 43.2% (19/44) at an 8 ppm, in addition to activity on three reference Prototheca strains. Overall, the study highlights the predominance of P. bovis as the causative agent of algal mastitis in bovines. Prototheca induced abnormalities preponderantly in the milk and mammary gland tissue of cows, and to our knowledge, our study is the first to apply clinical severity scoring in protothecal mastitis. In addition, the study underlines the activity of QA in low concentrations against Prototheca, indicating its potential use as an antiseptic/disinfectant in milking facilities and dairy environments. [ABSTRACT FROM AUTHOR]