I got a high PI (Bacteria Count) but I don't know why - 11 tips to find the cause
Viewing inside vats, receivers, and pipelines is a useful part of investigating cleaning issues.
You haven’t changed anything, yet you suddenly or gradually noticed an increase on your bacteria counts. This is frustrating. You work so hard to make quality milk only to get the bad news days and days later that you somehow fell short of your quality goal. There are some common things to check out when this happens. Hopefully these tips help you.
There are some key components to a good wash. Proper temps, chemical selection and dosing, water condition, and proper agitation or in the case of a pipeline, good slugs. The following steps dive deeper into this to help you gain control of your wash quicker.
Make sure hot water is getting to the vat. This means checking the inlet screens on wash valves, checking the temperature with a calibrated thermometer, and assuring that no mixing valves are open in the facility which would allow your hot water to blend. If you’re getting the “blend” issue, it’s time to consider check valves in the lines to prevent the hot water from back-feeding. You may even have a sign up to prevent the valves from staying open for that warm water mix you like but it’s hard to get 100% success on that. As a rule of thumb, a wash cycle should not drop below 120 degrees F. A few things can drop the temp from start to finish of the wash but if we do drop, it’s likely that fat is dropping enough in temp that it’s going back to sticky mode and plastering the insides of your system. This is also a good time to check your elements (when was the last time you had your water heater drained for removing sediment). Bonus tip - never leave your water heater on without water in it - that will surely destroy the elements as they need water on them to prevent them from blowing out.
Is chemical going into the vat? You may have everything hooked up right and maybe the chemical pumps are turning on, but you could have a hole in the line or a prime was lost. Some manuals will walk you through how to manually prime the chemical lines. This could also mean a worn-out chemical tube. Your route supplier or service provider can put you on a more aggressive maintenance cycle if you’re noticing them failing before each changeout. Another good method to manage this is to mark the drums each day or before each wash. Please remember to use appropriate safety gear when working with chemicals of any kind. Lastly, for now, make sure your drums aren’t old. This is especially true of products with chemicals like sodium hypochlorite (bleach/chlorine) or peroxide as they can gas off and depending on the opening size, weather, and sunshine on the drum, the chemical can lose its strength quickly. We recommend sizing such products to smaller containers in some cases to avoid degradation of the ingredients. A general rule of thumb is to use a detergent with chlorine, chlorine, or peroxide in less than 90 days. Some farms will need to consider even more strict timelines.
Are you getting agitation or slug in the tank or pipeline? You may not have the tools we do but a few from-the-hip guides are to watch the water coming in (easier to see in glass jars) to the receiver. You may be able to see it through a clear lid but another simple way is to place your hand on both top and bottom of various areas of the pipeline during a hot wash. Is the top as hot as the bottom? If not, you may not be getting a good slug. You should also notice a significant wham into the receiver when each slug gets there. The air injector and timer play a big role in this but leaks and other issues can also flatten the slug. It could also be that the water level isn’t right from when it was first setup. Getting this dialed in will likely require getting your service provider to make a visit.
Are you experiencing slow cool? Let’s first define slow cool. The ideal is to have enough cooling power (Btu’s) to get the milk cold as quick as you milk. Generally, the bacteria count doubles every 15 minutes. Since a passing count could be 5000 PI let’s use that for a math scenario. If you have 5,000 to start and have slow cool then in 15 minutes you’re at 10,000. In an hour you’re at 80,000 and if you’re still not below 40 after another hour, you’ve not reached 1,280,000. Pretty gross but it’s something to be very mindful of. Use your recording chart to monitor this if you’re not around during the milking/cooling routine. Is it keeping up on hot days? Is there a gradual decline? You may have a dirty condenser or low freon or a variety of other issues. The other change is simply that you’re doing such a good job with your herd that you’re putting more milk in the thank than you used to do.
Is your fresh cow pail clean? We’ve seen many dairies that use them, but it seems like it’s easy to not view these as a threat to your milk quality. The hoses, lid, gasket, pail and claw that you use for this can all be culprits of elevated bacteria loads. Remember the count doubles… imagine a pail that hasn’t been cleaned the best and used every 8 hours or so. Depending on your system, you may consider having your milking equipment provider install a connection to wash the hose and claw better and work out a product and protocol to keep the pail and lid clean for each use. In some of our investigations, we’ve found the pail to the main culprit - kind of a sleeper cell if you ask me.
Is there salt in the softener? We often say that good hot soft water is the cheapest chemical you can have on the farm. The harder the water, the more it binds up chemicals in the wash. Some products are capable of tackling this chemically with softening agents but they are also the more expensive options. In some cases, these are still a great option to assure quality wash. As much as chemical sales are nice, we’d rather see you have confidence in a well-designed wash so back to good water. Salt may be low or maybe worse yet, the softener stopped working. You may have a good water conditioning service company that you prefer. It may be a good idea to have the inspect and maintenance your system, especially if it’s been a while. You can do a quick test by purchasing a water hardness test or test strips. The latter aren’t as accurate but will give you an idea if it’s working at all. Most detergents will hit a threshold at 20 grains of hardness so keep that in mind. Other pollutants or sediment in the well can attribute to wash issues also. Some acids will react with things like barium and cause build ups. Getting a water sample that tests for such things can help if the obvious things are not the issue. Many such minerals are regional so you’ll often share the same issues as your close neighbors (if you’re on the same water supply).
Are fresh cows causing foul issues? The industry has become quite advanced with its dry cow therapy. This did bring on a heavy use of products like Orbeseal, LockOut and even some antibiotics like Spectramast. The suspension agent in some of these products tends to be happy to park in all kinds of nooks and crannies like in your meters, the receiver jar and hopefully never in the plate cooler (one of many reasons to always have a filter before the plate cooler).
Is a fresh filter being used as recommended? It’s not uncommon to use a filter longer than it is designed to but we know it happens. This can work fine even if we don’t condone it. That said, in some cases, you might be growing a culture on your filter that is where all your milk is running through so you’re basically seeing bacteria sponge into the filter surface and then hitch a ride on the milk passing through. Again, this is compounded with time and soil load.
Is milk of infected cows getting into the bulk tank? Have any infected cows shed, and their milk ended up going downstream into the tank? This can basically inoculate bacteria into the tank. If we have a few areas struggling at the same time - slow cool, slightly off chemicals or water temps plus an influx of more bacteria than normal (from a mastitis cow) then we can see a considerable uptick of counts.
Are the chemicals on point? This one is usually the first one to be pointed at but even if your route supply hates hearing the accusation, it should not be ignored, even if it’s unlikely. There is such a thing as a bad batch of product - just like anything we buy. A service tech or cleaning specialist can titrate the product (make sure not to empty your jug so there is something to sample) to test it against the goal PPM (Parts Per Million). Each manufacturer has a designated level for 1 oz. to 1 gal. or some similar method to know the baseline of the product. Bonus tip - that red acid being lighter is probably more to do with sunlight than anything and in most cases, acid products won’t notice a change from this and we’re only witnessing the dye sun bleaching. Regardless though, when we’re looking at systems, it’s wise not to assume.
Are the wear parts needing replaced? This is the dreaded one but many of the seals, gaskets, tubes, and liners on the farm are permeable. Butter fat and other milk components can permeate into the material and leech through. This can allow biofilms to form as well as regular bacteria colonies. Talk to your service provider to know for sure but most rubber products should be replaced annually. Some products can last longer. If you’ve done a shock, you may notice a drop in PI followed by a relapse of high counts. This is possibly due to the shock killing what has leached into the rubber parts but not far beneath that, more is still stuck, so the counts can quickly come back with vengeance. One way to tell if rubber parts are getting old is the to see if they turn your finger black when you wipe the seal or gasket. If this happens, the parts need replaced.
These ideas certainly don’t cover all the bases but should give you added confidence when tackling bacteria counts. Make sure to be clear about how aggressive you want to be when speaking with your service provider. Each farm approaches this differently based on their risk level. You may need to use the shotgun approach and knock out several things to regain control for the short term. In other events, you may choose to do one thing at a time to gain clarity about what’s making the impact on your counts.
Reach out or drop a comment to let us know what questions you have so we can help you keep control of your milk quality.
Having a good light is helpful when inspecting inside a bulk tank. Look for discolorations that may be a clue into what kind of build up you have. Be sure to share this with your service provider when dicussing your cleaning concerns.