Gleeson D, Edwards P, O’Brien B. Effect of omitting teat preparation on bacterial levels in bulk tank milk. Irish J Agric Food Res. 2017;55:169–75. Abebe R, Hatiya H, Abera M, Megersa B, Asmare K. Bovine mastitis: prevalence, risk factors and isolation of Staphylococcus aureus in dairy herds at Hawassa milk shed, South Ethiopia. BMC Vet Res. 2016;12:1–11. Mild mastitis: Abnormality of the milk is the main sign with little evidence of change in the udder and no systemic signs such as dullness and loss of appetite. Bulk farm milk samples were cultured to determine milk quality indicators such as TBC, CC, and CPS. Sample preparation was performed following the International Organization for Standardization protocol (ISO 8261:2001) [ 40]. Tenfold serial dilution of milk was performed by transferring 1 ml of milk of the previous dilution into 9 ml of 0.1% peptone water and was mixed by vortex. One milliliter of milk was discarded from the last dilution. Each sample was serially diluted up to 10 − 8 for TBC and 10 − 6 for CC and CPS. For some cows no matter how much antibiotic you use the chances of cure are very low. For example a 5-year old cow, treated at 150 days in milk, with a SCC of 2,000,000 cells/mL because of Staph aureus infection has approximately 1% chance of cure. The main reason for failure in these cases is that the antibiotics never reach the bacteria in sufficient concentration. These cows need to be identified and removed from the herd. Treatment will not be economic. Summary

The first is easier than the second. Mild mastitis can often disappear in a few days with no treatment or with massage and hand stripping of the quarter. However the bacteria may still be there. The same process may also occur after antibiotic treatment, particularly short courses with short milk withholds. Getting a visible cure without a complete bacteriological cure may result in an increase in subsequent clinical infections and a permanently raised SCC. Bava L, Zucali M, Sandrucci A, Brasca M, Vanoni L, Zanini L, Tamburini A. Effect of cleaning procedure and hygienic condition of milking equipment on bacterial count of bulk tank milk. J Dairy Res. 2011;78:211–9. https://doi.org/10.1017/S002202991100001X. Vairamuthu S, Sinnai J, Nagalingam K. Factors influencing production of hygienic raw milk by small scale dairy producers in selected areas of the Jaffna district, Sri Lanka. Trop Anim Health Prod. 2010;42:357–62. Increased knowledge of the udder microbiota is an important step in understanding mastitis dynamics, a disease affecting herd health and milk production yields world-wide [ 1]. To date, however, only a few studies have used HTS technologies to determine longitudinal shifts in the bacterial community of milk samples collected from healthy quarters [ 16, 22]. In the present study, we aimed to investigate the temporal changes in the udder microbiota of Norwegian Red cows over 5 months, which encompassed both the early and mid-lactation stages. The bacteria present were identified through amplicon sequencing of the V3-V4 region of the 16S rRNA genes. During library preparation, amplification in the negative controls were not detected in the qPCR system and it is hence unlikely that the samples suffer from contamination. For that reason, the controls were not included in the data analysis. In an attempt to acquire bacteria from deep within the udder, samples were collected after regular milking. This practice was used to avoid contamination of bacteria from the environment that had entered the teat apex [ 2, 3, 21]. Without invasive methods it is not possible to rid the samples of all contaminants, but Porcellato et al. [ 2] employed this type of sampling technique, and despite finding evidence of some environmental genera in the samples, their relative abundance was lower compared to milk taken from bulk milk tanks. This suggests that employing this sampling technique rids the samples of some of the environmental bacteria that are present in the teat apex. Three to four weeks were chosen as an interval between sample collection. This means that a transient subclinical intramammary infection could be missed as the pathogen could be cleared from the udder before the next sampling. However, no case of mastitis or mastitis treatment was recorded in the Norwegian Cattle Health Recording System through the duration of the experiment for the cows in the study.Chambers JV. The microbiology of Milk and Milk products. In: Robinson RK, editor. Dairy microbiology handbook. 3rd ed. New York: John Wiley & Sons, Inc; 2002. p. 39–90.

Lima SF, Teixeira AG, Lima FS, Ganda EK, Higgins CH, Oikonomou G, Bicalho RC. The bovine colostrum microbiome and its association with clinical mastitis. J Dairy Sci. 2017;100:3031–42. Amentie T, Eshetu M, Mekasha Y, Kebede A. Milk postharvest handling practices across the supply chain in eastern Ethiopia. J Adv Vet Anim Res. 2016;3:112–26. Sex of farm owner, experience in dairying, education level, training on hygienic milk production, material of milk utensil and udder/teat drying were not related to TBC, CC, CPS or the presence of S. aureus in bulk milk in univariable regression analysis. Multivariable regression analysis of risk factors associated with milk quality indicators and occurrence of S. aureus in bulk milk Over a long period of time both of these types of mastitis can persist, leading to chronic inflammation and damage in the udder ( chronic mastitis). Ngasala JB, Nonga HE, Mtambo MMA. Assessment of raw milk quality and stakeholders’ awareness on milk-borne health risks in Arusha City and Meru District, Tanzania. Trop Anim Health Prod. 2015. https://doi.org/10.1007/s11250-015-0810-y.ISO 7218:2007. Microbiology of food and animal feeding stuffs — general requirements and guidance for microbiological examinations. Geneva: International Organization for Standardization; 2007.

O, Solbu H, Refsdal A, Roalkvam T, Filseth O, Minsaas A. Results and evaluation of thirty years of health recordings in the Norwegian dairy cattle population. J Dairy Sci. 2007;90:4483–97. ISO 8261: 2001. Milk and milk products — general guidance for the preparation of test samples, initial suspensions and decimal dilutions for microbiological examination. Geneva: International Organization for Standardization. Brussels: International Dairy Federation; 2001. Pantoja JCF, Reinemann DJ, Ruegg PL. Associations among milk quality indicators in raw bulk milk. J Dairy Sci. 2009;92:4978–87. https://doi.org/10.3168/jds.2009-2329. Jayarao BM, Pillai SR, Sawant AA, Wolfgang DR, Hegde NV. Guidelines for monitoring bulk tank Milk somatic cell and bacterial counts. J Dairy Sci. 2004;87:3561–73. Elmoslemany AM, Keefe GP, Dohoo IR, Wichtel JJ, Stryhn H, Dingwell RT. The association between bulk tank milk analysis for raw milk quality and on-farm management practices. Prev Vet Med. 2010;95:32–40.Consistent with our findings, previous studies associated dirty barns [ 16, 49], dirty cows [ 16, 56], and soiled udder and teats [ 7, 15, 61] with elevated TBCs in bulk milk. In the present study, season significantly associated with TBC, with higher counts during the wet season than during the dry season. This agrees with previous reports [ 8, 19, 66]. During rainy seasons, the udder and teats of dairy cows are soiled with feces and mud, which increase microbial contamination of milk [ 8]. Premilking udder preparation is essential to produce high-quality milk [ 5]. A teat cleaning procedure that includes wet cleaning followed by manual drying with a towel reduces microbial contamination in milk [ 7, 51]. In this study, herd size did not influence TBC, which agrees with reports from Myanmar [ 56] and the USA [ 17]. The absence of an association between herd size and TBC in this study could be attributed to small differences in the number of cows among the farms. Fig 5: There is little sense in treating an older cow with chronic Staph aureus and a persistently high cell count Antibiotics Nacul HZ, Revoredo‑Giha C. Food safety and the informal milk supply chain in Kenya. Agric Food Secur. 2022;11(8):1–14. https://doi.org/10.1186/s40066-021-00349-y. Two consecutive petri dishes with colony counts between 30 and 300 per plate were considered for TBC, while plates that contained 10–100 and 15–300 colonies were considered for CC and CPS, respectively. Then, the bacterial count in the respective original sample was expressed as the number of colony forming units per ml (cfu/ml) of samples according to ISO 7218:2007 [ 43]. Isolation and identification of Staphylococcus aureus