Attention to hygiene will ensure high quality milk produced from healthy animals
High quality raw milk for a satisfactory economical gain - is directly linked to healthy animals
Maintaining a high standard of hygiene is one of today’s most important milk production objectives. The hygiene level directly influences the production’s economical result and dairies are enforcing this by steadily raising their quality requirements for raw milk. More importantly though, consumers are concerned about the safety of dairy products and the conditions under which these are produced. It is therefore critically important to ensure high quality raw milk can be produced from healthy animals under good hygienic conditions and that control measures are applied to protect human health.
FROM COW TO CONSUMER
Legal requirements for safety, quality and production conditions are currently enforced in many countries. European (EU) directives (89/362/EEC and 92/46/EEC) specify that raw milk must come from healthy animals and infectious diseases or foreign substances that are communicable to human beings through milk, should not endanger human health. Furthermore the equipment, tools and conditions under which milk is produced must fulfil certain minimum requirements. Milk’s content must also meet specified hygienic standards in terms of bacterial and somatic cell numbers present.
New EU regulations are in preparation to replace the aforementioned and to cover foodstuffs in general through the whole chain, from primary production to the consumer. Another reason for such regulations is to facilitate trade of milk and dairy products.
In accordance with legislation and driven by demands for efficient production of high quality products with trace-ability - dairies are now increasingly placing stronger demands on the quality of raw milk. New schemes are being successively introduced with stronger demands for differential payment of milk according to its quality. High somatic cell counts and residuals are strongly emphasised within these schemes. Additionally, the frequency of collecting bulk milk samples for analyses is increasing to meet rising safety, quality and trace-ability demands.
Consequently, it is extremely important for the milk producer to assure the best hygiene within production. Producing consistently high quality raw milk for a satisfactory economical gain - is directly linked to healthy animals and low veterinary treatment costs.
FROM FEED TO BULK MILK TANK
The final quality of dairy products offered to the consumer, is determined by characteristics of the whole process - from the animal’s feed production to the consumer’s table.
The hygienic and compositional quality of the feed plus drinking water can easily influence the raw milk’s quality. Animals consuming feed of inferior hygienic quality, may express digestive disorders - resulting in an unhygienic animal environment, with possibly poor hygiene during milking and negative animal health.
Poor quality silage may contain certain microorganisms or spores that spread in the barn during feeding and then transfer to the milk during milking. The quality of cheese originating from raw milk produced under such conditions may be seriously affected. Additionally, barn environmental factors may further negatively influence health and can include the animal’s udder health. Important udder health risk factors include barn type and design, along with stalls, manger height, floor type, bedding material, frequency of manure removal, cleanliness of stalls, hoof care, clipping of cow’s hair, barn humidity and the ventilation system. Hoof health is of particular importance herein.
Cows should be kept clean and dry, under comfortable conditions. When handling raw milk without considering the above factors, the milk producer risks obtaining it from unhealthy animals and may find antibiotic or veterinary drug residues present. The preventive measure is to control animal health by pro-actively considering the above and other factors.
Pre-milking udder preparation including fore milking and teat cleaning, has a direct mastitis-controlling effect because it reduces the number of pathogens. It also has an indirect mastitis-preventing effect because it minimises the risk of teat congestion and oedema to an effective teat-cup position, at the start of milking. The latter effect results in a shortened milking duration and improves the degree of udder evacuation.
Several investigations show the importance of practising good pre-milking teat or udder preparation procedures. Recent research confirms teats should be dry before milking. Wetting of the teats before milking followed by drying - did provide low bacterial counts in the milk. Washing of the whole udder should be avoided. If this is required, then it is critical teats are dried before attaching the milking machine.
Cotton towels were found to be superior to paper towels for reducing bacterial and spore counts in milk. Cleaning for 20 seconds was shown to be 50 per cent more efficient than cleaning for six seconds. One towel should be used per cow per milking. Cotton towels should be cleaned between milking sessions - preferably in a washing machine. Results from studies with the DeLaval Voluntary Milking System (VMS ) - show that automatic teat cleaning using the system’s specific teat-cleaning device, removes almost all spores from the teats.
The 89/362/ECC (EU) directive states: “Before milking of the individual cow, the milker must inspect the appearance of the milk. If any physical abnormality is detected, milk from the cow must be withheld from delivery”. This requirement can easily be fulfilled in conventional milking and appropriately executed by using a foremilk cup.
However with Automatic Milking Systems (AMS) it cannot be fulfilled if there is no human attendance during milking. Proposals have been submitted to change this directive but discussions are still in progress both by and between, legislators and scientists. The definition of abnormal milk is a highly important issue in this context. It is up to individual national authorities to decide how to apply the directives to AMS and to ensure safe and high quality in their countries until such new or modified directives are available.
Mechanical milk extraction should be conducted using machines that are designed, tested and serviced according to prevailing standards. These machines should also be used within accepted milking routines. Machine settings like milking vacuum and pulsation characteristics should be applied in accordance with the manufacturer’s recommendations. In general if this is followed, good udder health can be maintained. However if over-milking and inappropriate pre-milking preparation are practised, or high frequencies of liner slip are not prevented - udder health can be negatively affected. The latter can occur directly through increasing the number of new infections, or indirectly by affecting teat condition.
Post milking teat disinfecting
Research work carried out since the mid-seventies shows the feasibility of applying post milking teat disinfecting. Post milking teat dipping or spraying is widely used today. It is particularly effective in preventing environmental mastitis types.
Frequency of mastitis created during the dry period is an increasing problem. Such infections may persist into lactation and cause clinical mastitis or elevated milk somatic cell counts. Dipping dry cow’s teats using a special teat seal with a long lasting effect, is an important tool for helping control such mastitis.
Cleaning of milking equipment
The milking equipment should be cleaned as soon as possible after milking. A rinse cycle should initially be executed, using tepid water. The purpose of this is to remove residuals from the milk and soil in advance of the cleaning cycle.
Cleaning using detergents should be performed within sufficient time and with the cleaning solution at the highest possible temperature. It is important to have as much turbulence as possible for the cleaning solution during cleaning. Cleaning should be completed by flushing the milking system with clean water then draining it, or by flushing it with clean air. The milking system should be dry before the next milking.
Regular and efficient cleaning of the milking system is particularly important when using AMS. Investigations show the milking circuit should be cleaned at least three times a day within as equal intervals as possible. Cleaning less than three times a day may cause increased bacterial counts in the milk. Efficient cleaning of the cooling tank is equally important. Cleaning with acid detergent may be required at frequent intervals, depending on the hardness of the water.
Cooling of milk
It is generally recommended that milk be cooled to a refrigerated temperature within a few hours after milking and stored at 4 °C or below. Primary cooling might be required to avoid the blend temperature of the milk in the bulk tank, exceeding a certain level. Cooling of milk shortly after extraction is also important for minimising lipolytic activity. The latter process becomes more important the higher the milking frequency and also in AMS, where intervals between milking occasions vary for individual cows.
MONITORING AND RECORDING
On-farm monitoring, analysing and recording is becoming successively more important as herds become larger, plus various processes are automated and people involved become more specialised. Monitoring and recording is made for various reasons including checking if operations are properly carried out, are under control and also for trace-ability. It should be possible to take action and rectify any operation or situation that is out of control, following monitoring.