25) milking procedure - Babcock Institute - University of Wisconsin ...

Dairy Essentials - Lactation and Milkingparlors, the foremilk can be strippeddirectly onto the floor and flushed awaywith water as soon as it has been observed.—Milk of cows with clinical signs ofmastitis must be discarded.3) Wash teats with a warm sanitizingsolution.—Wash and massage all teats with warmwater containing a mild disinfectant.—Use water sparingly and avoid wettingmuch of the udder as water draining downonto the teats increases the risk of mastitisand the number of bacteria in the milk.—Use a single cloth or paper towel foreach cow. Use of the same cloth from onecow to the next increases the risk ofcontamination and transmission of mastitiscausingbacteria from cow to cow.4) Dip teats with a safe and effectivedisinfectant (optional).—“Predipping,” if allowed by the law, isan effective practice that reduces thenumber of new infections by environmentalmicroorganisms. Only products tested forpredipping should be used. Predippingconsists of immersing the teats in adisinfectant. To be effective, most predipdisinfectants must remain in contact withthe teats 20 to 30 seconds.5) Dry teats thoroughly.—Dry the teat thoroughly. Single usedisposable paper towels are the best way todry the teats, but are expensive. Cloths areacceptable when used only for one cow andprovided they are laundered betweenmilkings. Residual moisture on the teat,and water on the side of the udder, isloaded with bacteria and will eventuallycontaminate the liner, the teat, and the milk,creating risk of mastitis and lowering milkquality. In addition, dry teats minimizeslippage of the milking unit during milking.—The cow’s milk let-down reflex isinitiated as the teats were cleaned,massaged and dried.6) Attach teatcup within one minute.—Attach the milking unit to the teatswithin one minute after the start ofpreparation. Each teatcup should beslipped onto the teat with minimal entranceof air into the milking unit.7) Check milk flow and adjust milkingunit as needed.—Check that milk flows from each teat.—Adjust the position of the milking unit.Rapid and complete milking is possibleonly when the milking unit is properlyaligned. Usually, the front teatcups need tobe positioned slightly higher than the backteatcups. Some milking machinemanufacturers recommend a support armon which to rest the long milk and vacuumtubes and to adjust the milking unit into itsbest fitting position. Improperly alignedmilking units slip often and milk flow maybe restricted, both of which contribute tothe development of mastitis.—Do not leave a milking unit squawking.—Readjust milking unit as needed duringmilking. Air entering the teatcup maycause tiny droplets of milk to back flush athigh speed into the teat canal. Ifcontaminated, these droplets allow bacteriato enter the udder and cause mastitis. Thisprocess occurs more often near the end ofmilking, when milk flow is decreasing.8) At the end of milking, shut off thevacuum before removing teatcups.—Do not overmilk. The majority of cowswill milk out in 4 to 5 minutes. The forequarters are usually milked out earlier thanthe rear quarters, which produce moremilk. Thus the fore quarters tend to beslightly overmilked. Usually, this is not aproblem; one or two minutes of overmilking with a properly functioningmachine does not predispose the udder tomastitis.—Avoid stripping. In the past, it was acommon practice to massage the udderwith the milking machine in place to collect98 The Babcock Institute

25 – Milking Procedurethe last milk (stripping). This practiceshould be completely abandoned because itincreases the stress on the teat tissue andthe risk of air admission in the unit, therebyincreasing the risk of mastitis.—Shut off the vacuum to the milking unitbefore detaching the teatcups from theteats. Pulling a teat from a teatcup undervacuum increases the risk of teat damageand infection because it creates a massiveliner slip.9) Dip or spray teats with a safe andeffective disinfectant (teat dip) .—Dip or spray the bottom two-thirds ofeach teat with a mild disinfectant.Solutions that will not chap or irritate theteats include many commercial products,chlorhexidine (0.5%), iodine (0.5-1%) low inphosphoric acid, and hypochlorite (4%) lowin sodium hydroxide.10) Disinfect milking units (optional).—To prevent the spread of infectionbetween cows, it is becoming morecommon to disinfect teatcup liners beforeusing them for the next cow. The preferredprocedure is to dip the teatcup liners in abucket filled with clear water to rinse milkresidue. Then, the teatcups are submergedin a bucket with water and a milddisinfectant (15 to 25 milligrams iodine perkg of water, that is, a 15 to 25 ppm iodinesolution) for 2.5 minutes. Finally, the linermust be dried before attaching the milkingunit to the next cow. If not done properly,this step may enhance more than hinder thespread of mastitis. Many milking machinemay be equipped with an automatic systemto disinfect liners rapidly and effectively(backflushing).HANDLING THE COLLECTED MILKThe collected milk should be filtered,cooled and stored in a separate, clean milkroom. The milk can be filtered using an inlinefilter as the milk is pumped out of themachine or by passing the milk collected ina milking bucket through a filter manually.If the filter is disposable, it should be usedonly once. Alternatively, a cloth filter maybe used, washed and disinfected after eachmilking. The filter retains milk clots andother large particles, and after usage itsinspection helps to evaluate the overallhygiene of milking—in particular, thethoroughness of carrying out Steps 2 and 3above.Prompt refrigeration of the milk aftercollecting is vital to prevent multiplicationof bacteria and loss of quality. Ifrefrigeration facilities are not available,milk should be cooled to within 2 o C of thetemperature of the local water supply.Cooled milk should be stored ideally at 4 o Cuntil transported to the processing plant.Note that even good quality milkcontaining less than 10,000 bacteria/mlcannot be stored more than two days at 4 o Cwithout risk of quality deterioration. Milknot stored at 4 o C should be transported to amilk processing plant as soon as possible.CLEANING THE EQUIPMENTA milking machine functions properlyonly when cleaned thoroughly after eachuse. An impeccably clean machine isnecessary to harvest a milk of high qualitythat is safe and flavorful for humanconsumption, and that remains stable for along time (long keeping time or shelf life).When a milking machine is designed, theease of cleaning must be taken into account:• The material used to constructpipelines must be smooth (aluminum,stainless steel, etc.), durable and resistthe corrosion of acids and alkalinesolutions;• The machine must be constructed witha minimum of right angles (joints) toreduce flow disturbance and theformation of deposits;• All pipelines need to be adequatelysloped to provide drainage aftermilking and cleaning.University of Wisconsin-Madison 99

Dairy Essentials - Lactation and MilkingTable 1: Basic steps in cleaning milking equipment.StepWater Durationtemp (min.)Action and comments1-Pre wash 35 o to 45 o C Remove the bulk of the residual milk in the milking machine;“Pre-warm” the equipment for better action of the cleaningsolutions.2-Wash(alkalinedetergent 1 )3-Water rinsemin. 50 o Cmax. 75 o C10 A chlorinated product helps remove protein; the alkalinityremoves the fat, and a complexing agent (EDTA) prevents theformation of salt deposits depending on water hardness.(optional)4-Acid rinse 2 35 o to 45 o C 5 Neutralizes chlorine and alkaline residues (prolongs life ofrubber parts); prevents mineral deposits and helps preventmilkstones; kills bacteria.5-Water rinseWarm water helps the equipment dry faster.6-SanitationBefore using the equipment again, a sanitizing solution ofhypochlorite (200 mg per kg of water, or 200 ppm) reduces thenumber of bacteria on the equipment.1Examples of active agents in alkaline detergents: sodium hydroxide, sodium carbonate, trisodiummonophosphate, and polyphosphates. Dilution rate must be as indicated by manufacturer’s label.2Examples of acids: phosphoric acids or organic acids (acetic acid, citric acid, etc.). Most acid products containcorrosion inhibitors. Dilution rate must be as indicated by manufacturer’s label.Cleaning the outside of milking unitsWhen milking is finished, all visible dirtand milk deposits must be removed fromthe outside of the milking units and theflexible tubes by scrubbing and rinsing inclean water.Washing the pipelines and the insideof the milking unitsStrong flow turbulence of milk passingthrough a right angled pipeline and heatmay cause milk components (protein) toprecipitate and form “milkstones.”The basic steps to adequately clean amilking machine manually or with a“clean-in-place” system are summarized inTable 1. It is not possible to combine all thenecessary properties of a cleanser in onepreparation because elimination of fat andprotein film normally requires alkalinedetergent, whereas an acid solution isneeded for mineral deposits. Thusalternative use of alkaline detergents andacids is recommended. In addition, toassure the proper cleaning action of manydetergents, the following must also be partof the cleansing process:1) A mechanical action (manualscrubbing) or a high velocity flow(“clean-in-place” system) are neededfor a sufficient amount of time (contacttime) to lift and carry particles away;2) The total volume of water used mustbe sufficient to ensure contact betweenthe detergent solution and theequipment;3) The concentration of detergent mustbe adequate to obtain the desiredcleaning action;4) The water temperature must not betoo high or too low; temperaturedictates the effectiveness of manydetergents.100 The Babcock Institute