MilkTech International © MilkTech International Completeness of Milking

© MilkTech International

MilkTech International

Completeness of Milking

© MilkTech International 12-Aug-05 MTT.COM 2

Learning Objectives

This module will help you to:Understand the concepts of residual milk and “strippings milk”Measure and record the completeness of milkingInterpret measurementsMake recommendations


What is Undermilking?

Undermilking is incomplete milkingRefers to the event that an unacceptable amount of milk is left in the udder after teat cups are removed post-milking. Milk left in the alveoli is called “residual milk”. Milk left in the ducts or udder cisterns is referred to as “available milk” or “strippings”.


What is Undermilking?

Residual milk cannot be removed, even by careful machine stripping or hand-stripping,without an intramuscular injection of oxytocin. High amounts of residual milk may result from incomplete milk ejection associated with poor milking routines, frightened or nervous cows, sore teats, or uncomfortable milking equipment.


Why does Undermilking Occur?

Incomplete removal of the “strippings” milk occurs when:the teat cups of the milking machine are removed before the last of the available milk drains into the udder cisternsthe milk pathway in one or more of the four quarters becomes blocked near the end of milking.

blockages occur when clusters do not hang evenly on the udder and/or when one or more of the four teats moves too deeply into its teat cup (referred to as "teat cup crawling").


Causes of Incomplete Milking

Liner design not suited to the type of teats or animals being milked.Poor condition of linerClusters that fail to hang evenly on udder due to connecting hoses that are too long, too short, twisted, or poorly aligned relative to the cow.Clusters that are too light in relation to the bore of liner used and/or the system vacuumHigh milking vacuum levelsA mismatch between the claw inlet and the short milk tube causing partial closure of the short milk tube where this tube joins the claw.


Problems with Incomplete Milking

Some studies suggest that incomplete milking might increase the percentage of sub-clinical infections developing into clinical infections.Severe under-milking can reduce lactation and total milk yield in high producing cows.


Problems with Overmilking

Severe overmilking will increase “machine on” time and contribute to hyperkeratosis, or roughening of teat ends, when using some types of liners.Severe overmilking, in combination with high milking vacuum and high compression lines, can pull out too much keratin from the teat canal and prolong the time required for teats to reseal after milking. This may contribute to increased mastitis infection in cases where cow housing hygiene is poor.


So what is an acceptable amount of milk to be left

in the udders post-milking process?


Measuring Milk After Milking

There are a several ways to measure the milk left in the udder after milking:Hand stripping by quarter (or udder)Machine stripping by quarterMachine stripping by cluster

Each method extracts a different average amount of milk, and therefore each method has different interpretation guidelines.


Hand Stripping by Quarter

Video clip 1 demonstrates the hand stripping by quarter procedure.

1) Begin stripping into a measuring device immediately after the machine comes off of the cow. Measure the amount extracted from each quarter.2) If a quarter yields less than 100 ml, record it as completely milked.3) If a quarter yields more than 100 ml, stop stripping as soon as 100 ml is obtained and record the quarter as under-milked.


Hand Stripping by Quarter

With some practice you can learn to gauge the amount of milk left in a quarter and can do away with the measuring flask. (see video clip 2)Remember to begin hand stripping as soon as the machine comes offPerform vigorous hand stripping for no longer than 15 seconds on each teat


Machine Stripping by Udder

Strippings milk can also be measured by re- applying the milking machine after it has been removed. This method is only practical for farms that have milk meters.

Video Clips 3 and 4 demonstrate the machine stripping method


Machine Stripping by Udder

Note the milk yield after automatic removal.Reapply the machine and apply enough downward pressure to re-establish milk flow but not so much pressure that liner slips occur.Continue machine stripping for up to one minute.Record the final milk yield and the difference between milk harvested and strippings milk.

the extra milk harvested by machine stripping.

With this method the dividing line for under milking is about 1200 ml or 1.2 kg.


Machine Stripping by Quarter

You can also machine strip by individual quarters but this requires special equipment and is usually only warranted for research purposes.


Interpreting Hand stripping by quarter

When hand stripping by quarter:a herd with less than 20% of quarters that is under-milked is a very cleanly milked herd.That means that 80% (or more) of quarters have less than 100 ml of strippings milkand no more than 20% of quarters have more than 100 ml of strippings milk.


Interpreting Hand stripping by udder:

When hand stripping by udder:A herd with less than 20% of udders that are under milked is a very cleanly milked herdThat means that 80% (or more) of udders have less than 250 ml of strippings milk.And no more than 20% of udders have more Than 250 ml of strippings milk.


Interpreting Machine stripping by udder

When machine stripping by udder:The average of all cows should be less than about 500 ml or 0.5 kg per udder A herd with less than 20% of udders that are under milked is a very cleanly milked herd

That means that 80% (or more) of udders have less than 1200 ml of strippings milk.OR no more than 20% of udders have more than 1200 ml of strippings milk.


Let’s Review

Undermilking is an unacceptable amount of milk is left in the ducts or cistern of the udder after the milking machine is removed.


Some Causes of Under-milking

Teat cups crawl and stop milk from flowing from the udder into the teats

Liner design not suited to the type of teats or animals being milked.Poor condition of linerClusters that are too light in relation to liner and/or milking vacuum milking machine removed to early

Milking vacuum is too high


Some Causes of Under-milking

Incomplete milk ejection associated with poor milking routines, or nervous cowsClusters hang unevenly on udder Mismatch between the claw inlet and the short milk tube causing partial closure of the short milk tube


What Problems Can Result?

Incomplete milking may increase percentage of sub-clinical infections developing into clinical infections or reduce lactation/total milk yield in high producing cows.Severe overmilking may increase “machine on” time and contribute to hyperkeratosis, or roughening of teat ends, when using some types of liners.Severe over-milking can contribute to a prolonged period of open teat canals after milking.


Recommendations

For a quick screening of the completeness of milking use the hand strip by quarter method.

If more than 20% of quarters are under milked (>100 ml of strippings) then further investigation is requiredThis method a rough estimate and gives a ‘pass/fail’ mark This method is also very good for measuring systematic under milking in particular quarters that may be a sign of uneven weight distribution of milking unitsUse the bimodal statistical analysis (see barnyard statistics module) to determine sample size and confidence levels for pass/fail diagnosis.


Recommendation

For a more precise measure of the average strippings per cow use the machine stripping method by udder on farms with milk meters or the hand stripping by udder method on farms without milk meters (or bring your own milk meter). Machine stripping, on farm with meters, may be easier to implement on a large number of cows than hand stripping methods.

This method also gives better statistical power to detect differences between treatments (e.g. different liners) than the pass/fail method used for hand stripping by quarter. (see barnyard statistics section for statistical methods)


Recommendation

For research level investigation the machine strip by quarter method gives both a more accurate measure of strippings milk and distribution across quartersThis method provides the most information but requires special test equipment and careful technique and is also more disruptive of the milking routineConsult the research methods module for more detailed information.

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