Milking Technology

8/13/2019 Milking Technology

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Milking technology

Milk letdown

Ancient people were already aware of the importance andneed to stimulate the milk ejection reflex. On paintings incaves the effect of vaginal stimulation for milk ejection wasdescribed as well as the importance to have the calf close tothe cow during milking. How important is the stimulation of the

milk ejection reflex during milking in our modern dairy cows?s it a phenomenon! the importance of which! has disappearedthrough genetic improvements? n order to answer those"uestions the biology behind milk letdown will be discussed.

#uring milking and suckling nerve receptors in the skin of theteatthat are sensitive to pressure are activated. $his mechanical

stimulation causes impulse transmission to the pituitary glandin the brain whereby the hormone oxytocin is released. $hehormone is transported to the udder via the blood. n thepicture below a schematic figure of milk ejection reflex ispresented.


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Milk ejection reflex. Stimulation of the teats (1), caused nerveimpulse transmission via the spinal cord (2) to the pituitarygland (), !here oxytocin is released and thereafter istransported to the udder via the "lood (#).

n the mammary gland the hormone causes the myoepithelialcells surrounding the alveoli to contract whereby the milk ispressed out to the milk ducts and milk cisterns! demonstratedin the picture below.


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$ contracted alveolus.

$he time it takes from beginning of teat stimulation to milkletdown is about %&'(& seconds! but varies from cow to cowand also within the cow depending on the stage of lactation. thas been postulated in former times that the oxytocinsecretion is momentary and the release just happens onceduring milking. )ecent research has! however! indicated thatoxytocin is released during the whole milking procedure.

$he milk ejection reflex! including oxytocin secretion! can bestimulated in many ways such as application of different tactileteat stimulation! by the presence! sight or hearing of the calfand by feeding concentrate in relation to milking!demonstrated in the picture below.$he most efficient stimulation of the teats for milk let down isperformed by the calf. An optimal milking techni"ue should

therefore imitate the suckling. $he suckling done by the calfincludes prestimulation! milk intake and post stimulation.

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Why teat stimulation?Prestimulation
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+restimulation is in general the procedure performed beforeattaching of the teat'cups! including drawing control milk!cleaning and drying the teats! massaging the teats and udder.#uring the pre stimulation the receptors in the teats are

stimulated and the milk ejection reflex is activated.

Milk ejection can "e stimulated in different !ays, such astactile stimulation of teats, sight or hearing of the calf, noisefrom the milking machine and in some cases "y feedingconcentrate.

$his results in milk letdown where oxytocin already has

started to act on the myoepithelial cells when the milkingmachine is attached to the udder. A shorter milking time! ahigher milk flow and in some cases a more efficient milkremoval is the benefit of a proper pre'stimulation. ,ince themilk ejection is already activated when the milking machine isattached to the udder! the milk flow curve very seldom isbimodal! demonstrated in the pictures below.


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%ffect of 1 min premilking manual stimulation on averageoxytocin profile (red line) and milk flo! ("lue line) duringmilking. Milking "egan immediately at time &' arro!s sho!start time of stripping ($dapted from Mayer et al . of%ndocrinol, 1&**, 1+#).

$his means that there is no delay in flow between milk comingfrom the cisterns and milk coming from alveolar area! whichimproves teat treatment. $he prestimulation can be performedeither manually or by the machine. However! so far we haven-t found a mechanical variant as efficient as the hand.

Post-stimulation

+ost stimulation can be looked upon as the procedure wheremanipulations of teats and udder take place after the milk flowgenerally has decreased or stopped. Machine or handstripping are examples. n experiments! performed on dairycows! it has been found that machine stripping or extra poststimulation /the last minute of milking was shifted from

machine milking to hand milking0 resulted in four to fivepercent higher milk production. n other species it was foundthat continued suckling after milk intake stimulates a highermilk production. $he effect on milk production due to post'stimulation might be explained by activation of local regulatorymechanisms within the udder. $hese mechanisms might


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influence the emptying of the udder and also the capacity ofthe milk secreting cells.

*ack to topStimulation during milking

How the tactile teat stimulation on the teat during milking isperformed is of great importance. t has been demonstratedthat milking related release of the hormones oxytocin andprolactin is influenced by the tactile stimulation of the teats. nexperiments where hand milking was compared to machinemilking /hand milking is the milking procedure which imitatesthe calf suckling very well0 it was found that the milking relatedreleases of these hormones were both higher and prolonged

during hand milking compared to machine milking. $his effectcan partly influence the milk production capacity.#uring teat stimulation also local regulatory mechanisms ofnervous origin in the mammary gland can be activated. A verygood example demonstrating the importance of localmechanism in the mammary gland is the lactating kangaroo.,he can feed two young /joeys0 of different ages from two

adjacent mammary glands with milk adapted to the specialdemands for each young. $he bigger young has his /her0 ownteat producing milk related to his /her0 demands! while thesmaller young has his /her0 own teat producing milk related tohis /her0 special demands! despite that both glands areexposed to the same hormonal and nutritional environment. tis only through the different suckling application thecomposition as well as the amount of milk to be produced in

the specific glands can be regulated to the different demandsfrom the young.t has also been indicated in dairy cows that activation of localmechanisms is of importance for both milk production capacityand milk composition. n experiments it was found that hand


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milking resulted in a higher milk production and milk with ahigher fat content compared to machine milking!demonstrated in the picture below.

#aily yield of fat in machine milked /blue line0 and hand milked/red line0 front teats during three periods1 A' when both frontteats were machine milked. *' when one front was hand

milked and the other was machine milked! 2' when both frontteats were machine milked again /four cows0 /Adapted from,vennersten et al 3. #airy ,ci. 4%5647! 766&0.

$he physiological mechanism behind these results is not yetfullyelucidated. $here are indications of the existence of local

nervousreflexes in the udder! influencing mechanisms whereby thecapacity in the milk secreting cell can be increased. ndeed!already during the fifties and sixties )ussian scientists wereaware of this phenomenon.


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Another very interesting finding in monogastric animals andruminants is that suckling8milking also might activatehormones in the stomach. However! what does this mean andwhat is the importance of this? magine a cow producing 7&&

kg milk per day ' a very high milk production capacity. 9ivingthis high amount of nutrients and calories is not possibleunless the animal is consuming large amounts of nutrients.#uring the suckling8milking procedure the hormones in thestomach are activated! demonstrated in the picture below.,ome of these hormones which are activated during milkinginfluence the feed intake behaviour and some of thehormones exert a growth stimulating effect of the gastric

mucosa. t is therefore possible that the milking relatedrelease of these hormones is involved in the adaptation of thegastrointestinal tract during pregnancy and lactation in orderto facilitate the enhanced food intake which is of vitalimportance. Having in mind that milking might influence feedintake indirectly points to the importance of appropriate cowmanagement around milking.


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-oth milking and feed intake activates gut hormones.

2onse"uently! the mammary gland is an organ that is

controlled by hormones and supported by nutrients in order toproduce milk.However! the mammary gland is an organ that also controlsits own function as well as it controls other organs in the body.,ome of these control systems are activated through themilking8suckling process! which points to the high importanceof how the machine is stimulating or acting on the teat duringmilking.

*ack to topWhy efficient milk removal?

:fficient milk removal is one important point regarding milkingtechni"ue and milking routines. $here are many reasons forthis. :fficient milk removal results in a higher milk yield. $hecomposition of the milk is influenced! in particular the fat


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content. ;hen the farmer is paid according to the fat contentof the milk it is significant to empty the udder as completely aspossible! since the last portion of the milk has the highest fatcontent! demonstrated in the picture below.


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emptied completely while the other one was unmilked. $heemptied gland was immediately filled up with sucrose solutionand in this gland the milk secretion continued despite the highudder pressure. 2onversely! in the unmilked udder "uarter the

milk secretion was inhibited. $his observation strengthenedthe hypothesis about inhibitor substances present in the milk!which suppress milk secretion. hours

milking interval is often practiced. $welve hourBs interval is themost optimal milking interval with twice daily milking. Milkproduction /kg milk0 increases a couple of percentage pointswith e"ual intervals compared to une"ual milking intervals.;hat is the mechanism behind this phenomenon? Milksecretion starts to decline 7& hours after the previous milking!while udder pressure is increasing. %= hours after previous

milking the milksecreting process has stopped! demonstrated in the picturebelow.


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/he rise in intramammary pressure and the fall in milksecretion rate !ith lengthening milking intervals ($daptedfrom 0amann odd, in Machine milking and lactation, ed

-ramley et al, 1++2).


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from ='>= more milk per day. n addition lactation becomesmore persistent and prolonged. $he reason why milkproduction increases with a more fre"uent milking could be amore fre"uent exposure of hormones stimulating milk

secretion to the mammary gland. However! as mentionedabove the milk contains an inhibitor with negative feed backcontrol on milk secretion. A more fre"uent removal of thisinhibitor therefore results in a higher production. An interestingfinding in this respect is that cows with a small udder cisternare more sensitive to the fre"uency of milking. $he smaller thecistern the greater the effect of fre"uent milk removal on milkproduction and the bigger the cistern the less the response to

fre"uent milking.


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lactation ($dapted from 0amann odd, Machine milkingand lactation, ed -ramley et al, 1++2).

Cdder health has been reported to be improved with morefre"uent milking. However! it is worth noticing that teats havemore sores! chaps and lesions with more fre"uent milking. Onthe other hand! the rates of new infections have decreasedand the level of somatic cells in the milk show a tendency todecrease. More fre"uent milking leads to a more fre"uentrinse out of bacteria from the gland! which partly can explainthe observations with an improved udder health!

demonstrated in the picture below.

/eat end uality scores per group (group 2 milked t!ice aday, group three times a day and group # four times a day)and lactation period. (3rom 4pema -enders, 4n 5roc. 4nt.Symp. on 5rospects for $utomatic Milking, 1++2).


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Milking fre"uence

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E

Milk yield 7&& 77F 77=

#ry matter intake 7&& 7&% 7&F

DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

4ncrease in dry matter intake (6) and milk production (6)!hen co!s !ere milked three and four times a day comparedto t!ice a day ($dapted from 4pema -enders, 4n 5roc. 4nt.Symp. on 5rospects for $utomatic Milking, 1++2).

How is this possible? t has been observed that the morefre"uently milked animals are drawing on their body reservesto a greater extent than twice daily milked animals. t is alsopossible that their metabolism is more efficient due to a morefre"uent activation of endocrine systems related tometabolism. ndeed! it has been indicated that gastrointestinal

hormones are activated during milking and it has beendemonstrated in monogastric animals that the milking relatedhormone oxytocin is involved in the maternal metabolism.Maybe the most important benefit of more fre"uent milking isimproved animal welfare. t has been observed that most highyielders will not lie down during the last few hours beforemilking. Moreover! many high yielders are producing up to (&

kg milk per day and are milked twice a day with '7( hourmilking intervals. $his means that those cows are yieldingnearly F& kg milk during morning milking. 2ows with such highamounts of milk in the mammary gland must be exposed to atremendously high udder pressure which undoubtly will causediscomfort. ndeed it has been observed that high yielding


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cows want to be milked more fre"uently than twice or threetimes a day when they have their own choice.n summary! increased milking fre"uency affects the high

producing dairy cow in a positive way with respect toproduction! health and animal welfare according to currentobservations. A more fre"uent milking than twice daily isbetter adapted to cows normal behaviour and need! since thecalf is suckling as fre"uently as F'4 times per day.

*ack to topMilking routines

t doesn-t matter how well the genetic potential and feeding ofthehigh yielding dairy cow has been taken into consideration inorder to achieve optimal milk production if milking routines andmilkinge"uipment are not optimal. $he milking routine has to beperformed in a consistent way. $he tube alignment has to becorrect and also the installation of the milking e"uipment is

important.

An optimal milking routine includes different steps such as5fore milking! cleaning teats and udder! manual prestimulationand teat dipping when needed after milking. A proper manualprestimulation of the teats facilitates milk ejection. $heimportance of pre'stimulation has been discussed previously.

How will an optimal pretreatment be performed?:xperimentally the importance of a strict milking routine hasbeen demonstrated from a production point of view. Gactationproduction was studied where cows were exposed to differentmilking routines. A strict routine /cleaning and drying teats andudder for around %& seconds and application of milking


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machine within (& seconds from start of stimulation0 resultedin an increased lactation production of about F=& kg. $hecontrol treatment was a routine with a short drying time andvariable waiting time! demonstrated in the picture below.

%ffect of pretreatment on milk production, second and thirdlactation co!. 7o!s !ere exposed to a standard milkingroutine consisting of 189:+s premilking stimulation and

1.2289:&,2* min interval and a control routine consisting of1;89:*s premilking stimulation and .&


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startusing routines which will create positive emotions for the cow.#uring the seventies scientists demonstrated that feedingduring milking resulted in a more efficient udder emptying!

higher peak flow and a tendency towards increasedproduction. $he observation resulted in a recommendation tofeed concentrates in the parlour in some countries.*ut what was the mechanism behind this observation and is itworthwhile to continue feeding concentrate in the parlour?nterestingly! it has been found that feeding during milkingboth prolonged and increased the milking related release ofthe hormone oxytocin! demonstrated in the picture below.


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$he milk ejection reflex might be inhibited as well. $here aredifferent types of inhibition! centrally in the brain or locallywithin

the udder. ;hat then can cause inhibition of the reflex?)ough treatment of the cows by the milker! discomfort duringmilking caused by the milking machine! unfamiliarsurroundings and inconse"uent management are severalexamples.

n order to stimulate the milk ejection reflex and not to inhibitit! it is

very important to treat the cows in the most proper way bothduring and before milking. Milking represents a very complexse"uence of conditioning processes. $he very first cuesindicating approaching milking /noise of milking machinebeing turned on! release of cows from stanchions! etc0 startsthe complex series of sychophysiological processes thatprepare the cow for milk let down. f this process is disturbedin one way or another milk ejection can be inhibited. $herefore

the recommendation will be consistent timing of routines! suchas udder wash! teat cup application and synchroni@ation ofother routines such as feeding or preparing of bedding. $heevents should take place in a regular order every day.

*ack to topTeat treatment/mastitis

$he prere"uisite to produce milk in an economical way is tohave a relatively high yield with high "uality! which means

high production from healthy animals not suffering from anykind of disease in the mammary gland. Mastitis is the mostcommon and costly disease in dairy herds. n many cases thefarmer is only aware of the clinical cases! demonstrated in thepicture below.


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7linical cases ($) and su"clinical cases (-) of mastitis($dapted from >elson 5hilpot, Mastitis Management, 1+;).

t has been reported that clinical mastitis rates are generally

>&'7&& cases87&& cows per year. ,ubclinical infection levelsare ='%= of "uarters infected by a major pathogen bacteria.$he clinical mastitis is rather easy to detect for the farmer. $hesymptoms are clotting and discolouration of the milk! and thegland becomes hard! red or swollen and in severe cases thecow has fever and loss of appetite. $he subclinical mastitis


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can be harder to detect! since both the milk and udder canappear rather normal! while the somatic cells in the milkincrease! demonstrated in the picturebelow.

iagnoses of mastitis $:clinical, -:su"clinical.


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;hat is mastitis? Mastitis is an inflammation in the mammary

glandwhich can be caused by bacterial infections or trauma. ;henbacteria are growing! they release metabolites and toxins thatstimulate the defence mechanisms in the cow. $heinflammation response leads to a migration of white bloodcells from the peripheral circulation into the udder. $he cellcount of the milk increases from normally 7&& &&& cells8ml orless per udder "uarter up to several million per ml. $he

increased cell count is accompanied by an activation ofseveral milk en@ymes! demonstrated in the picture below.


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/he inflammatory process involved in mastitis ($dapted from$.. -ramley. 4n Machine milking and lactation, ed -ramley etal, 1++2).

$he pathological conse"uences of mastitis are tissue damageandalteration of secretory function. $his leads to reduced milkyields and changes in milk composition. A correct estimationof the loss in milk yield is hard to do! since non'infected udder"uarters tend to compensate for the decrease in yield of theinfected "uarter. $he mechanism behind the regulation of this

compensation is still unknown. )egarding the altered milkcomposition! fat and lactose levels are dropping! while totalprotein levels change only slightly serum proteins areincreasing and casein are decreasing leading to deterioratedcheese making "uality. $he milk concentrations of ions areincreasing resulting in an increased milk conductivity!demonstrated in the picture below.

/he relationship "et!een somatic cell count in milk, theuantities of the components in milk and milk production


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(3rom ?iesecke et al, 4n 5ractical mastitis control in dairyherd, 1++#).

How is the milking machine influencing mastitis? $he milkingmachine can facilitate the transmission of pathogens betweencows and between udder "uarters. $he action of the milkingmachine can also cause bacteria to move from the exterior ofthe teat into the teat sinus! caused by excessive vacuumfluctuations.


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evelopment of teat end thickness values (7utimeter) "eforeand immediately after milking in relation to different milking

methods and trial periods (0amann and Stanit@ke,Milch!issenschaft, #*


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knowledge about animal re"uirements for space! air supply!thermal protection! nutrition! behaviour etc. )egardingbehaviour it is important to have an understanding of thecowBs ability to detect events in her surroundings! memori@e

the specific significance and act accordingly. As an example!efficient management re"uires good knowledge about learningabilities of dairy cows! in particular when it comes to milkingparlours and robotic milking systems.

$he different ways and importance of learning can beexemplified as follows. ;hen cows are introduced to a new

area of a barn! it is useful to let the animals get accustomed tothis area by their own choice! without forcing by the personnel.$o find out that a new area is safe usually re"uires >'F visits.;hen heifers are to be introduced to the milking parlour thetime for them to learn entering the parlour can be reduced ifthey are given the opportunity to freely investigate the parlourbefore the beginning of their lactation.

;hen it comes to milking it is important to have in mind thatthe motivation for this cannot be expected to be of suchpredictable nature and such strength as to those for drinkingand food intake.


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confiding interaction. t is important for the animals to perceivea positive and safe interaction with the herdsman. ndeed!animals handled aggressively are more fearful of humans andfear is often created by uncertainty.

$he herdsmanBs behaviour could have direct economicalconse"uences. ndeed! experimental results demonstrate thatdairy cows treated with pleasant handling milk more per year.$he herdsmanBs handling in the parlour during milking/touching of the cows through patting and stroking0 canencourage the cows to more easily enter the parlour andexhibit less stress and thereby less inhibition of milk letdown.

Also! the use of the voice influences the cowBs production. thas been observed that in the higher yielding herds theherdsman talked to the cows far more often than in the loweryielding herds. $alking with instead of talking to theanimals was associated with high yielding cows.

n many herds today it is not unusual for animals to showdifferent types of more or less abnormal behaviour! such astongue rolling and bar biting. $his could be a result of too littleactivity for the animals and possibilities to practice theirnormal behaviour such as search for food. 2ows on pasturedonBt show oral stereotypes.


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influence animal health! animal welfare and production.

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