Monitoring coverage of teat spray systems and maintenance

Post milking teat disinfection is an essential part of any mastitis control plan, and over the last 40 years has been shown to be very effective in controlling the spread of mastitis.  With the correct product, it also has major benefits in improving and maintaining teat skin condition so that the teat can withstand the rigours of milking.  Dry and cracked teat skin is not only more difficult to keep clean, but also harbours populations of mastitis causing organisms.  In addition during the milking process cows suffer discomfort and even pain when teat skin is dry and cracked.  This impacts on the milk let down response and leads to ineffective milking out.  This in turn can then go on to cause damage to the integrity of the teat and therefore the first line of the udders defence.

Pre-milking teat disinfection can also have benefits in improving teat cleanliness prior to unit attachment, can help in the control of environmental mastitis, in particular, and aid the milk let down response as part of a complete milking routine.

Manual teat spraying with a vacuum operated lance is arguably the most common form of teat disinfection, although automatic systems in all their guises are becoming more popular.

However, what constitutes teat disinfection?  The 2013 study funded by Ambic into the efficacy of teat barrel coverage by manual spraying found significant variation in both teat end and teat barrel coverage.  With some farms they were technically carrying out teat disinfection, but in practice it was totally ineffective and a waste of time and resources.  So how can effective teat spraying be monitored.

The simplest method is to check chemical use.  With manual teat spraying the average volume recommended per cow per milking is 15 ml, which was confirmed in the Ambic funded study in 2013.  Automatic teat disinfectant systems are designed to use different amounts per cow per milking, with some allowing the volume to be altered.  This information will be readily provided to you by the manufacturer/supplier.  The following table is a guide to how long the various sizes of containers should last, based on twice and three times per day and two herd sizes and 15 ml per cow per milking.

Table 1.  Teat disinfectant use (days).

  Size of container Average number of cows in milk/day
150 400
2x/d milking 3x/d milking 2x/d milking 3x/d milking
25 litre 5.5 3.7 2.1 1.4
200 litre 44.0 29.6 16.6 11.1
1000 litre 222 148 83 55

If containers are lasting much longer then insufficient chemical is being applied and the benefits of teat disinfection are being lost.  However, use is just one part of the story.  How effective is the chemical being applied?  Spraying udders is not particularly effective!  Observation is all – when teat spraying look at how effective the task has been done.  The aim is to not only cover the teat end but also all the teat barrel.  So often it is only the side of the teat nearest the operator that gets covered with disinfectant, with little or none applied to the front plane.  The problem is more noticeable in rotary and 90° rapid exit parlours, due to the position of the teats in relation to the operator.

This can easily be checked by using a piece of paper towel to “dab” the far side of the cows’ teats (but choose your cows carefully). If little disinfectant appears then you realise the task is not being effectively carried out.  With labour at a premium on many farms it is tempting to rush this part of the milking routine – but reflect on how long one case of mastitis adds to each milking.  A more detailed monitoring of the effectiveness of teat disinfection can be carried out, where teat end and teat barrel coverage is scored.  Coverage of the teat end is either a Hit or Miss and the front and rear planes of each teat are scored out of 50 – so if half the front side of the barrel is covered the score is 25.  If all the rear side is covered the score is 50, giving 75% teat barrel coverage.  This assessment can be done by farm staff or by using consultants.

Although the aim is for 100% of teat ends and teat barrels to be covered, a realistic target is 100% of teat ends and at least 50% of each side of the teat barrel.   These targets are the same for manual or automatic teat spraying – and teat dipping.

Besides the human element, equipment has to be regularly serviced.  The ends of the vacuum operated lances often become worn as the spray head usually ends up scraping along the operator pit floor.  A good spray pattern is essential. The spray nozzle can also get blocked – removing and thoroughly washing out is a simple but effective job.  Do not unblock with a needle or similar as this will adversely affect the spray pattern.

Teat disinfection is a vital part of a mastitis control programme, but is must be followed and applied effectively.  Simple monitoring and observations will help ensure success.