September 3, 2008

Managing Milk Quality

One of the hardest things to get through to new recruits coming into dairying was that “dairy farming” was not just about growing grass and milking cows while cleaning up afterwards.

I tried to enthuse them by saying they were entering “the Food Industry”. I tried to impress them further by telling them is was actually “the Health Food Industry” and that they were producing “nutraceuticals”! I cannot claim any success as there still seems to be as many problems with milk quality today as there were 30 years ago.

The following is edited from advice by Grant Norton, Ecolab, Christchurch, NZ.


The aim of milk quality management is to achieve a Grade-Free season every year and achieve the highest classification in annual farm dairy inspection.

Good signs
• No problems at any time during the plants regular inspection.
• No breakdowns of equipment risking milk quality.
• Well-documented systems that cause no risks.
• No grades during the year.
• Staff who enjoy working there.

Bad signs
• A dirty dairy that you would not want to work in.
• A dairy you would not want to drink the milk from.
• Regular grades during the season over the whole range of defects.
• Staff who do not enjoy working there.

Why bother about Grade Free (GF) certificates?

A GF certificate is one of the most important items to have in your CV. The number of farmers and staff who fail to get them is very disappointing. They are very much easier to lose than to gain.

Farm owners are the official recipients of the certificate, so make sure that you as Herd Manager get a copy, and also get copies for all staff involved.

Once you have more than one certificate, it then becomes an even greater motivation tool for the staff as nobody wants to be the person who blows it. You can get the boss to pay bonuses on winning it, or provide surprise benefits that again are highly motivating. It’s like a team on a winning run – it’s important that you keep on winning.

The GF certificate is such a highly motivating document that a copy needs to be displayed in some prominent place at the farm dairy for all to see every day. Some farmers have a row of them above the fireplace in the front room for visitors to notice! That tells you how proud they are of their operation and their product. They know they are in ‘the health food business’ and their farm dairy is not a ‘shed’! A shed is where the tractors and bikes are kept. Where you milk the cows is now a ‘neutraceutical harvesting plant’.

Retired dairy farmer Graham McBride in the Waikato got fifteen 100% GF certificates in fifteen years of farming. He had them framed and displayed in the farm dairy which was great industry public relations for overseas visitors.

Why GF certificates go down the drain?
• Running mastitis cows in the milking herd.
• Mastitis-treated cows not marked properly ending up in the milking herd with cups on them.
• Heifers and induced cows not milked for 10 milkings before saving to the Bulk Milk Tank (BMT).
• Main herd cows not milked for 8 milkings before saving to BMT.
• Flushing milk out of plant with water when milk volumes are low.
• Not doing a hot wash night and morning while colostrum is going through the plant.
• Not enough milk in the BMT after the first saved milking to reach the stirrer to allow it and the refrigeration unit to be left on without the milk freezing.
• Not doing a RMT on all quarters of all cows before saving their milk to BMT.
• Colostrum tank not marked and locked properly so tanker empties it into the supply.
• BMT not washed properly before new season supply.
• Dirty milk line – full of patches of cheese with a hard layer of protein over it. Disturbance lets the bugs out.
• Plate cooler half blocked from misuse or lack of filters.
• Wet udders allowing bugs and sediment entry via the liners.
• Allowing cups to fall in dung and sucking into system.
• Blocked cracked and leaking jetters.
• Not enough flow through the jetters.
• Hot water too cold – someone turning thermostat down trying to save power.
• Cutting corners on the wash regime to save money or to get out of the shed early.
• Plate cooler water too warm in summer.
• Refrigeration unit taking too long to bring milk down to 7 degrees.
• Rubber ware being used too long before replacement.
• Not using enough cold water for pre rinse before hot wash.
• Forgetting to take the milk line out of the BMT before the wash routine.
• Cows fed silage or put on crop or feed pads before milking causing feed taints in the milk or high bacteria numbers on the udder.
• Not changing a split inflation straight away.
• High somatic cells at the end of lactation (often on the first or last collection) when milk volume is low and cows giving less than 5 litres.
• Test buckets dirty.

How to gain a Grade Free certificate.
• Where practical always run a separate mastitis herd and this herd should always be milked after the main herd.
• Remember to disconnect from the BMT as soon as the main herd has finished.
• Even if you are running a separate mastitis herd, these cows need to be clearly marked in some way so that if for some reason they end up in the main herd they are still identifiable and cups are not put on.
• Heifers and induced cows need to be withheld from the BMT for at least 10 milkings. These cows could have colostrum present for this long.
• It needs to be 8 milkings for main herd cows but also make sure they are through their Dry Cow Treatment withholding period before their milk goes into the BMT.
• Be very careful flushing milk out of a plant when your milk volumes are low. In the early part or late part of the season you may be only saving 300 litres of milk/milking. It takes very little water to mix with that small amount to cause a freezing point grade. Remember you will be saving 4 milkings before pick up so that is also 4 lots of water. Water can also be contaminated with coliform bacteria so could contaminate your milk.
• Colostrum melts in the range of 48-60°C so it is imperative that a hot wash is used night and morning while you have colostrum going through the plant. If you don’t remove all the fat (i.e cold wash at night) there is a possibility that you could have some remaining that contains some inhibitory substance that could contaminate the next milking.
• If you do not have enough milk in the silo to leave the refrigeration unit on all the time, your milk will warm up allowing the bacteria to start multiplying which will cause a grade very quickly. Coliforms can double in numbers every 20 minutes. Start with 50 bugs/ml and do the maths!
• Strep uberis causes environmental mastitis. A uberis-infected quarter can contain millions of bacteria. One cow with one infected quarter if it is bad enough, is enough to give you a bacto ‘F’ on an early pick-up. Remember she will go into the BMT 4 times before pick-up.
• Also remember a cow can have a low somatic cell count and still have a strep uberis infection. Do a RMT test on every quarter of every cow before you start saving her milk. Treat her if necessary.
• Clearly label all colostrum tanks to prevent accidental pick-up by the tanker driver.
• BMT should be checked thoroughly and hand scrubbed if necessary. Make sure you check the back entry, under the door seal, outlet, stirrer and behind and below the door on the inside. Generally it will be a protein soil so scrub with a chlorinated alkali solution. Wear gloves and goggles. Do not scour the affected area with a product like jiff as this will scratch the surface of the silo making it easier for soil to stick to.
• The whole plant should be checked and cleaned and rubberware replaced as necessary during the off-season. You should also do monthly checks during the season and fix any issues before they start causing a problem. If you see a problem building in the milk line, identify the cause, fix it and then scrub the area clean.
• Always have a filter in place if anything is going through the plate cooler. Be careful not to tear the filter while putting up the housing. Filters are designed for a single milking only.
• If you have to wash udders before cupping wipe with a paper towel.
• Keep the milking platform as free from dung as possible. Dung can contain up to 5 billion bacteria/gm. If you suck it up into the system and get tested, you grade.
• During every pre-wash cold rinse, you should check the performance of every jetter. If a jetter is blocked or leaking, fix it before you carry on. There should be a minimum of 3 litres of water/minute going through every jetter. If unsure put it on a test bucket and time it for a minute and measure. You should have at least 3 litres in the test bucket.
• Hot water needs to be a minimum of 80° C at the cylinder. Remember fat doesn’t start to melt till 48°C so you must maintain your wash above 60°C. If you don’t, soils will start depositing back onto the surface.
• Don’t ever cut corners with the wash regime. Use the required amount of cold rinse (at least 15 litres/set of cups) and then your hot wash at 10 litres/set of cups, with the right amount of chemical in this hot wash. Your wash solution needs to contact the milking surface for a reasonable amount of time to enable it to soften and then remove the soil loading.
• Keep an eye on the temperature of the plate cooler water especially in the warmer months. Remember that a plate cooler working efficiently should cool your milk down to within 2 degrees of the cold water going through it. Therefore the colder your water is the less energy your refrigeration unit will use to get the stored milk down to 7 degrees. This also creates less time for bacteria to multiply while the milk is above 7 degrees.
• If rubberware is not replaced as it wears out, it starts to break down and absorb milk into it, creating a home and a food source for bacteria, especially thermodurics. All black milk hoses and droppers should not be used for any longer than 2 seasons before replacement. Inflations have a 2500 milking life. After that they are a lot less efficient and will not milk cows out properly. Milk pump diaphragms should be replaced at season start and again just before Christmas.
• If you have a mechanical milk pump then the mechanical seal on that pump should be replaced before the start of every season regardless.
• Be very careful flushing milk out of the plant with water. Always remember to disconnect from BMT before doing your plant wash.
• If you have to use feed pads of feed crop or silage, then the best time to do this is straight after milking to avoid contamination of milk with taints and bacteria etc.
• If an inflation splits inside the shell, you will get bacteria entering the milk through that split. You will also have milk enter the pulsator airline which needs to be rinsed out while it is still wet. If left it can cause grade issues. Take the end off the pulsator line and rinse it out with the wash down hose.
• Hand stripping cows is the only true way of assessing the amount of mastitis in the herd. If somatics are on the rise, then this should be adopted and suspect cows given a RMT. Cows that are producing low levels of milk should be dried off, as they will be contributing the major share of the bulk somatic cell count. Remember somatic cells do not increase once the milk has left the cow.
• Test buckets should be treated just like the plant and washed after every use. Pay particular attention to the milk hose as this is the part that comes into contact with the plant. Quarter milkers should be banned from the dairy altogether.

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