PARAMETERS IN MILK QUALITY AND MASTITIS
3 The milking routine and its effect on milk quality
This point is highlighted by the increased rate of intramammary infections during the dry period when teats are not being regularly sanitized and the keratin lining of the teat canal is not being routinely replaced. As an alternative to washing the teats with water, a large number of dairy producers choose to use teat disinfectants prior to milking to sanitize the teats. The teat disinfectant will work significantly better on teats that are not covered with dirt and manure. The use of premilking teat disinfectants has been studied for decades. Various products can be used as disinfectants such as iodine-based solutions, iodine-based gel, sodium hypochlorite, dodecyl benzene sulfonic acid, chlorine, chlorhexidine, phenolics and alcohol. Gibson et al. (2008) demonstrated that a chlorine-based dip followed by a dry wipe was effective in
Figure 2. Teats should be adequately cleaned even if the udder is dirty.
controlling cow mastitis. Robertson et al. (1994) demonstrated that teat orifices colonized with Staphylococcus aureus were 3.3 times more likely to be associated with intramammary infections. Therefore, reducing the number of mastitis-causing pathogens prior to milking is extremely important. Given the number of mastitis-causing organisms on nonsanitized teats compared with teats that are chemically disinfected, the inclusion of a disinfection step in the premilking routine is recommended. The use of a premilking teat disinfectant along with drying will reduce the milk’s bacterial count as well as the risk of new intramammary infections by reducing the number of pathogens on the teat skin prior to the attachment of the milking machine. It is important for teats to be free of dirt before the disinfectant is applied even when the udder is dirty (Fig. 2).
The teat disinfectant should remain in contact with the teat for 20 to 30 seconds for proper teat sanitation to be achieved.
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A variety of teat disinfectants can be used and their availability is dependent on the local legislations in the country where they are used. In the USA, teat dips are considered a drug and iodine-based predips are very common while their use is limited in the European Union due to fear of iodine residues in the milk. Lowering iodine concentrations from 1 % to 0.1–0.5 % in predips reduces iodine residues in milk without changing efficacy (Nickerson, 2001). Water is not commonly used in the USA to clean the teats. If water is to be used in the premilking routine, only a small amount should be applied and milkers should avoid wetting the entire udder and/or flank area. Excessive water makes drying nearly impossible and might increase the incidence of new mammary infections by transferring mastitis-causing pathogens to the teat orifice. It is important for the teats to be dry and well stimulated before the milking machine is attached.
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