Milking routine 2: Milking and post-milking disinfection
Ideally, a milking machine is as effective as possible, extracting the maximum amount of milk in the shortest amount of time possible (high milk flows per minute). The teat cups should be placed on the teats after stimulation (to shorten the milking time), avoiding air leakage that may cause vacuum fluctuations and milk reflux. It is also important to correctly align the milking unit with the cow and ensure the tubes are not twisted. The milker should watch the process carefully and not perform any other tasks, such as feeding (which is very common).
The milking unit can be removed manually or automatically. It is important not to milk the cows for longer than necessary. Don't try to get the last milk drop out. There is an amount of residual milk that should remain in the udder, and its extraction would cause irreparable damage to the sphincters. The volume of this milk varies from one animal to another, but it can reach about 700 g in an adult cow (500 g in a first-parity cow).
Post-dipping is an essential point in the prevention of mastitis. After milking, there is a film of milk left on the surface of the teat that constitutes an excellent culture for microorganisms. The disinfectant dip should be applied on the surface of the teat that has been in contact with the teat cup immediately after removing the unit. Traditionally, dips have been used to prevent contagious mastitis, although barrier dips may play an important role in prevention of environmental infections as well. The products should have a good disinfection capacity and leave the teat skin in the best condition possible (many of them include cosmetic substances for the skin and sphincter, sometimes at the expense of the disinfectant).
Post-dips are usually formulated with:
- PVP, at 5,000 ppm.
- Sodium chlorite (0.64 %) + lactic acid (2.64 %).
- Lauricidin (0.25-1%) + capric and caprylic acid (1.25-5 %).
- Chlorine dioxide (ClO2).
As with pre-dips, the use of one product or another will depend on the studies that support its use (see lists published by the NMC). So-called "plastic dips" are also available, which form a film around the teat that is removed at the next milking. They hinder transpiration and their use involves a risk of isolating bacteria responsible for contagious mastitis between the skin and the plastic film. It should be remembered that cows produce their own seal 40-45 minutes after the milking process.
Apart from disinfection, it is necessary look out for any abnormalities or dryness of the skin and sphincter, which may worsen in cold environments.
- Disinfection of teat cups: recommended especially for the control of contagious mastitis. Modern milking machines have a backflush system. The traditional use of hypochlorite has not been demonstrated to reduce the incidence of contagious mastitis.
- Control of animals with mastitis: they should be identified and milked at the end of the milking session, to separate their milk and avoid accidents with bacterial inhibitors.
- Cows should remain standing after the milking session while their sphincter closes (40-45 minutes). That is why the best recommendation is to provide them with fresh feed upon their leaving the parlour.
- Milk animals with an excessive production three times (60 litres/day). The purpose is to reduce trauma to the teats (the cluster will be placed for a shorter period of time). Overmilking is usually unavoidable, as the cows usually require longer to be stimulated. An economic estimation of the costs that a change in the management routine would entail should be carried out.