Physiology of milk excretion during milking. Conditions for obtaining good-quality milk How often do you need to milk: get acquainted with different options and opinions
The mammary gland secretes milk continuously. In the intervals between milkings, it fills the capacitive system of the udder: the cavity of the alveoli, excretory ducts, milk canals, milk ducts and the cistern. As the system fills, the pressure increases and, reaching a certain value (40-50 mm Hg), becomes a factor inhibiting milk formation.
Milk in the udder can be divided into cisternal, alveolar and residual milk. Cisternal milk can be obtained by inserting a catheter (metal tube) into the cisternal pine before milking; alveolar (located in the ducts and alveoli) is secreted when milking this pine or other teats of the udder; residual milk can be extracted by injecting the animal with large doses of the hormone oxytocin. During normal milking of an animal, only cisternal and alveolar milk is milked.
The removal of milk from the udder during milking of a cow is a rather complex process, involving neuro-hormonal mechanisms. It involves the nervous system, endocrine glands and udder muscles. In order for their interaction to occur, the cow must be prepared for milking: the udder must be washed and massaged. In this case, the nerve endings of the areola area of the udder and nipples are irritated. Excitation along the nerve pathways reaches the spinal cord. From here, one part of the signals is sent to the brain, and the other to the mammary gland. In response to these signals, the posterior lobe of the pituitary gland secretes the hormone oxytocin, which after 20-30 seconds appears in the blood and reaches the mammary gland through the bloodstream, causing contraction of the muscle cells surrounding the alveoli and small tubules. The alveoli seem to be compressed, the tubules are shortened, and their lumen increases. Favorable conditions arise for milk to exit into the gland ducts. At the same time, the nipple sphincter relaxes.
When the entire mass of the alveoli contracts, large milk ducts and cisterns are filled with milk, the pressure inside the udder increases sharply (up to 50-70 mm Hg) and the milk ejection reflex occurs.
The hormone oxytocin is released not only when the udder is irritated. The same effect is caused by the sound of the milking machine being turned on, the appearance of a milkmaid and mechanical irritation of the nipples during milking. A sharp noise, fear, pain or the appearance of a new milkmaid can slow down the milk release reflex; apparently, this is due to increased production of the hormone adrenaline in the body.
The hormone acts for a short time, as it is destroyed by its antihormone. The concentration of the hormone in the blood required for milk production is maintained for 6-8 minutes. During this time, the cow needs to be milked quickly.
When preparing a cow for milking, milk supply does not occur immediately. A certain time passes until the body’s response to irritation occurs. This is the hidden period of milk production. Usually this period in cows is 40-50s, although in some animals due to individual characteristics there may be significant deviations. The duration of the latent period of milk production largely depends on the filling of the udder before milking. With strong filling, especially at the beginning of lactation or with long breaks between milkings, it can be 30 seconds; with low milk yield and frequent milkings, it can exceed 1 minute. During lactation, the latent period of milk production lengthens significantly and in the 6-7th month of lactation, as a rule, lasts more than 1 minute.
The process of extracting milk from the udder itself has 3 clearly demarcated phases. This is due to the nature of the change in pressure inside the udder under the influence of the hormone oxytocin and milk found in the gland. In accordance with the change in pressure inside the udder, the milking speed, or, as it is also called, the milk yield rate, also changes.
During machine milking, all of the indicated phases of milk production are clearly visible through the sight glass and milk hose in the milking machine, and the milkmaid has the opportunity to correctly navigate the process of milking the cow: take additional measures to influence the mammary gland and turn off the milking machine in time.
It is impossible to evoke the milk ejection reflex a second time during the same milking. This is due to the temporary non-excitability of tissues that occurs after strong stimulation during the period of previous milking (resting phase). In practical conditions, this phenomenon can be observed during milking of highly productive cows 2-2.5 hours after the main milking. In this case, the rate of milk production decreases sharply, and for a more complete extraction of milk from the udder, a long stimulating massage is required during the milking period. However, even in this case, up to 40% of the milk and 60% of the milk fat that was present in the gland before milking remains unmilked.
In the first 4 months of lactation, the rate of milk production in cows is almost at the same level. With good preparation of animals for milking, it can be more than 2.5-3.0 l/min., with average- 1.5-1.8 l/min. However, already in the 6th month the rate of milk production decreases significantly (by an average of 27-38% at intervals between milkings of no more than 12 hours). At the end of lactation, it is almost impossible to evoke a full milk let-down reflex.
Young animals, as a rule, give milk faster and more fully. They have a much shorter latent period of milk production, i.e. The release of milk under the influence of udder massage occurs earlier than in adult cows. This must be taken into account when organizing the milking process on the farm.
A delay in the start of milking when allowance occurs leads to incomplete use of the milk ejection reflex. As a result, a lot of unmilked milk remains in the udder. If repeated frequently, this leads to premature self-starting of cows, as the process of milk formation is disrupted. Disruption of the usual milking routine also contributes to an increase in the amount of residual milk in the udder. All this must be taken into account in practical work.
Milk, being an excellent nutritious product for humans, at the same time serves as a good breeding ground for the proliferation of various microorganisms, including pathogens. Therefore, during the milk production process, dairy farm workers must constantly monitor to limit the introduction of microbes into the milk. To do this, it is necessary to improve the routes for passing livestock to pasture, maintain the necessary order on the farm territory, plant it with landscaping, keep the approaches and entrances to the farms in good condition, and regularly update disinfection mats and disinfection barriers.
In the barn, manure should be promptly removed, bedding changed, and walls disinfected and whitewashed. Cows must be cleaned, and the most contaminated areas of their body must be washed with water with the addition of disinfectants. If cows are milked in stalls, then rough and dusty feed should be distributed no later than an hour before milking, followed by ventilation of the room before milking.
In the process of obtaining milk, milkmaids and operators of machine milking of cows are required to strictly observe the rules of sanitation and hygiene. Before putting on milking machines, the udders of cows should be thoroughly washed and dried with a thoroughly wrung out absorbent cloth, constantly contained in a disinfectant solution.
The first portions of milk must be milked in a separate container. Microorganisms located on the surface of the teat, bedding and soil enter the udder through the teat canal. True, as a result of the bactericidal effect of udder tissue, a significant part of it dies. However, the most persistent forms of bacteria persist. There are especially many of them in the lower part of the nipple canal. This portion of milk (bacterial plug) must be milked into a special mug with a black mesh. The mesh allows you to promptly identify diseases of the mammary gland, since in this case protein flakes and mucus, sometimes blood, secreted by the inflamed udder will be retained on the mesh. In this way, it is possible to prevent mixing of milk obtained from a sick cow with the general milk yield of the herd, since impurities in mastitis milk spoil the entire milk yield. Toxins released into milk when cows become ill are not neutralized during pasteurization and can cause human illness with tonsillitis, scarlet fever, as well as toxicosis, allergic conditions and poisoning. Milk from cows affected by staphylococcal mastitis is especially dangerous. Milk contaminated with such microflora is discarded.
Dairy utensils and equipment for milking, processing and storing milk can become a significant source of bacterial contamination. Therefore, careful care of the equipment and the use of effective cleaning and disinfection products make it possible to obtain high-quality milk with low bacterial contamination.
Farm personnel must strictly observe personal hygiene rules. Before milking the cows, the milkmaid must put on a clean robe that is not used for any other work, tuck her hair under a scarf, and wash her hands thoroughly up to the elbows. warm water with soap and then rinse with a disinfectant solution. Fingernails should be cut short, and if there are wounds or abrasions on the fingers, a waterproof bandage should be applied. Persons working with milk must undergo a medical examination at least once a quarter, and once a year be examined for carriage of intestinal pathogens, helminths and tuberculosis. New workers entering the farm should be accepted only if they provide a certificate of medical examination and the conclusion about the absence of bacterial carriage of pathogenic and toxigenic microbes.
Persons suffering from open tuberculosis, purulent open ulcers, various contagious eye inflammations, etc. cannot be allowed to work with milk.
To prevent pathogenic microflora from entering the milk, if an animal sick with a dangerous disease (foot-and-mouth disease, brucellosis, leptospirosis, etc.) is detected in the herd, it should be immediately isolated from the rest of the herd and immediately notified to a veterinarian. A sick animal is milked last and in a separate container. The milk obtained from him is not mixed with the total milk yield of the herd, but is used in accordance with the instructions of the veterinarian or destroyed. After draining milk obtained from a sick animal, the dishes must be thoroughly washed and disinfected. In case of mass diseases of cows with diseases in which milk can be used for human food, it should be subjected to special heat treatment directly on the farm before being sent to the dairy plant.
Dangerous sources of bacterial contamination of milk are flies and rodents. On the body and legs of one fly there can be up to 1.5 million microbes, including pathogenic ones. Therefore, systematic control of flies and rodents must be carried out on farms by chemical, mechanical and biological means.
Water used for washing cows' udders, hands, utensils and equipment can also serve as a source of bacterial contamination of milk. To prevent this, use only potable water. Under no circumstances should the farm use water from contaminated wells and pits located near manure storage facilities, latrines, sewage dumps, or rain water.
For getting good quality milk It is important to follow the milking rules. When milking by hand, you must use your fist and not a pinch. When milking by machine, you should not allow teat cups to remain on the udder, as this can lead to inflammation in the mammary gland. Incomplete milking entails a decrease in milk fat content, since part of the milk fat remains in the udder.
Instability of the vacuum regime is also one of the main causes of mastitis. In addition, violation of the regime leads to rupture of the membranes of fat globules, as a result of which the quality of milk decreases.
The law prohibits any additives to milk for any purpose. Milk containing preservatives (formalin, hydrogen peroxide, potassium dichromate, chlorine preparations, etc.) and neutralizing (soda, alkali, etc.) substances should not be accepted at milk processing plants. It is also unacceptable to contain antibiotics in milk, since almost all of them are allergens. Heat treatment usually does not destroy them, and, therefore, does not reduce their negative effect. The indiscriminate entry of antibiotics into the body of humans and animals contributes to the rapid formation and spread of antibiotic-resistant races of bacteria. Therefore, when treating sick animals, especially mastitis, as well as when adding premixes containing antibiotics to feed, you should follow the appropriate instructions.
Zootechnical and veterinary specialists must strictly adhere to the established rules, terms and methods of processing animals. In this case, you should be guided in each specific case by special instructions and recommendations. It is also necessary to observe quarantine periods for grazing and feeding grass from meadows and pastures after treating them with chemicals.
Dairy industry enterprises should not accept milk with a rancid, musty taste, pronounced smell and taste of onion, garlic and wormwood. Such milk is not suitable for the production of high-quality dairy products. In this regard, it is necessary to exclude from the diet of lactating cows feeds that negatively affect the quality and technological properties of milk. They should not be accidentally eaten by animals. It is important to carry out work to improve the botanical composition of grasses in pastures.
It is also known that when animals eat herbs of the buttercup family, milk develops a red tint and an unpleasant taste, horsetails - a bluish color (and it quickly turns sour), and sour sorrel - a sour taste and rapid clotting. The cream obtained from such milk does not churn into butter well.
When keeping cows on cultivated pastures, the quality of milk depends on soil and climatic conditions, the botanical composition of grass mixtures, the phase of plant vegetation, the dose of mineral fertilizers, irrigation and other agrotechnical measures. Legume-cereal grass mixtures are more balanced and biologically complete for dairy cattle than cereals, due to the increased content of sugar, essential amino acids, calcium, phosphorus, trace elements and other nutrients. When an increased dose of nitrogen fertilizer is applied to cereal pastures, the dry matter content in the grass decreases. Grazing cows on cereal pastures with an excessive dose of nitrogen fertilizer has a negative effect on the microbiological processes in the rumen, the coefficient of use of feed nitrogen for milk production decreases, and it worsens chemical composition and technological value. When cows are fed legumes and cereals, the biological value of milk increases. Therefore, the correct use of green feed in combination with others, in particular with concentrates, contributes to the production of high-quality milk with good technological properties.
During the winter, hay is a good source of nutrients for dairy cows. It helps normalize digestion and produce high quality milk. Briquettes and pellets serve as valuable food for cows in winter. However, it should be borne in mind that an increased content in the diet of grass meal granules or other finely ground roughage and concentrates will change the processes of rumen digestion, lead to excessive formation of propionic acid in the rumen and a decrease in acetic acid, and this leads to a decrease in fat content and an increase in the amount of non-protein nitrogenous substances in milk.
Dairy feeds are root and tuber crops rich in easily digestible carbohydrates (sugar and starch). However, an excess of them in the diet leads to a decrease in the fat content of milk, a deterioration in its taste and technological properties. Therefore, they should be fed in recommended quantities in combination with hay, haylage and silage.
You cannot feed excessive quantities of tops or silage from them, cabbage, rutabaga, turnips, otherwise the milk will acquire a specific taste, and its fat and protein content will be reduced.
It should be remembered that an excess of concentrated feed in the diet of cows (more than 400 g per 1 kg of milk) has a negative impact on the health of animals and the quality of milk. An excess of cakes and meals has a particularly unfavorable effect.
Lack of energy in the diet not only reduces milk yield, but also negatively affects the content of fat and protein in milk and the quality of dairy products. An excess of non-protein substances, including synthetic nitrogenous substances (urea, etc.), is also unacceptable.
To ensure the required mineral composition of milk, and, consequently, its good taste and technological properties when producing cheese, condensed milk and other canned milk, cows’ diets must be balanced in terms of macro- and microelements and vitamins. Vitamin deficiency is eliminated by feeding appropriate feeds and supplements.
An important condition for obtaining high-quality milk is strict adherence to the daily routine. You should also properly use various odorous substances, lubricating oils, etc. For example, treating the udder teats with an antiseptic emulsion or vaseline oil can only be done after milking the cows.
Milk adsorbs foreign odors and retains them firmly. At the same time, its hygienic and technological properties are reduced. This must also be taken into account when organizing feeding and housing, as well as when milking and transporting milk.
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9. Physiological basis of the process of machine milking of cows. Methods for extracting milk from a cow's udder.
The udder of a cow (Fig. 2.2) consists of four independent lobes, often unevenly developed. Most cows produce more milk in their hind lobes than in their front lobes. Each lobe has 1 mammary gland, 7 connective tissue, 2 milk ducts and a nipple. In the mammary gland, milk is produced from the animal’s blood, which flows through the milk ducts into the milk cistern 3 and into the nipple cistern 4.
The elementary structural unit of the mammary gland is the alveolus - a vesicle with a diameter of 0.1 to 0.4 microns, the walls of which consist of a single layer of secretory cells. The alveoli are located around the common excretory duct, forming a lobule that includes 150–200 alveoli (lobule length 1.5 mm, width 1 mm, height 0.5 mm). The lobules are combined into larger lobes with large ducts flowing into the cavity above the nipple - the udder cistern. The cow's udder nipple has a cistern 4, separated at the top by a round fold from the udder cistern 3, and at the bottom passing into a narrow teat canal, surrounded by a dense muscle ring - sphincter 5. Between milkings, the sphincter is tightly compressed, preventing milk from flowing out of the udder. Milk does not flow out of the udder between milkings also due to the special arrangement of the milk ducts, which have expansions and contractions, as well as special sphincter-like thickenings. Breast tissue is like a sponge and milk can only be extracted by squeezing it. Compression is carried out by contraction of the myoepithelium under the influence of the hormone oxytocin. By the beginning of the next milking, the udder tanks contain from 4 to 20% milk. The main part of milk - 80-96% - is located in the alveoli and small ducts of the mammary gland. It is relatively easy to extract milk from the cisternal section; it flows out on its own if you overcome the resistance of the nipple sphincter by inserting catheters into the nipples. To obtain milk from the alveolar region of the udder, it is necessary to induce the milk ejection reflex in the cow.
The entire process, the beginning of which is the irritation of the udder receptors, and the end of which is the transfer of milk from the alveolar region to the udder tank, is called the milk ejection reflex. This is a neurohormonal reflex, since irritation from the receptors of the mammary gland to the central nervous system goes along the nerve pathway, and from there the excitation is transmitted to the mammary gland both through nerves and through hormones.
The operator, by washing and massaging the udder, irritates the nerve endings (receptors) 6, from which excitation, passing through the nerves, enters the brain through the spinal cord. From the central nervous system, signals return to the mammary gland in two ways. One path is purely nervous (the first phase), when excitation returns to the mammary gland from the spinal cord, causing vasodilation and increasing blood circulation, expansion of the milk ducts and cisterns, which facilitates the passage of milk into them from the alveolar region. As a result of the first phase of the milk ejection reflex and relaxation of the nipple sphincter, the calf can receive a cisternal portion of milk within 2-6 seconds after the start of sucking.
The second phase of the milk ejection reflex includes, in addition to the nervous one, a hormonal component. This phase begins 30–60 s after irritation of nipple receptors and lasts 4–6 minutes. In response to irritation of the receptors of the mammary gland and the receipt of signals in the brain, the hormone oxytocin is released into the blood from the posterior lobe of the pituitary gland, which reaches the mammary gland with the blood and causes contraction of the stellate cells of the alveoli, while increasing the permeability of the walls of the secretory cells. Under the influence of oxytocin, the ducts shorten and expand, facilitating the passage of milk into the tanks, from where it can be easily removed by the milking machine.
As a result of repeated milking in constant conditions on the farm and the coincidence in time of the act of milking with certain environmental factors (time, place, sequence of operations on the udder, etc.), conditioned milk release reflexes are formed in cows and a stable stereotype of behavior during machine milking is developed.
Milk ejection that occurs as a result of direct irritation of the receptor zones of the nipples and udder is called unconditional reflex. Milk ejection that occurs as a result of the action of external stimuli on the nervous system through other analyzers of the animal (visual, auditory, olfactory, etc.) is called conditioned reflex. The milk ejection reflex (conditioned and unconditioned) occurs simultaneously in all lobes of the udder, despite the different amounts of milk formed in them.
The technology of machine milking of cows involves the following operations:
Creating a vacuum in the air system of the milking machine (installation);
Preparing the cow's udder for milking;
Putting teat cups on teats;
Milking and transporting milk to a storage tank;
Removing glasses from nipples.
All the most labor-intensive operations of machine milking are performed mechanized. The exception is preparing the cow's udder for milking, putting on and removing teat cups, which take 15...20% of the total milking time. Recently, robotic milking machines have been developed (mainly abroad - Holland, USA), in which the search for the cow's teats, putting on glasses, and removing them after milking is completed automatically. Udder washing and massage are also automated.
The main factors in organizing cow milking are the frequency and intervals between milkings. The frequency of milking is established taking into account the capacity of the udder and other biological characteristics of the cows, as well as the specific economic conditions of keeping the animals.
The intensity of milk production depends on the filling of the udder with milk. When it is less than half full, it is not recommended to milk cows.
Milk can be extracted from the udder naturally (calf suckling) by hand and machine milking.
Machine milking can be done in two ways: sucking milk using a vacuum and squeezing milk from the teats. The latter method, which imitates manual milking, has not become widespread due to the complexity of the design of milking machines.
To implement the technology of machine milking, technological lines are created, which represent a system of interconnected machines and units that perform all the necessary milking operations.
Zootechnical requirements for machine milking technology are determined by the physiology of the animal, and boil down to the following.
1. Preparatory operations on the udder must be completed within one minute.
2. Milking cups should be put on after the cow has let in her milk.
3. Milking of the most highly productive cows should be completed in 4…6 minutes. (milking speed up to 2l/min.).
4. There must be a complete drainage of milk from the nipple chambers of the teat cups during the period of greatest milk production.
5. It is necessary to ensure that the cow is completely milked by the machine without manual milking.
6. For push-pull machines, the teat cups must not be left on the teats after milk has stopped flowing from the udder.
In accordance with the requirements for technology, there are also requirements for milking machines. They should easily and quickly ensure the opening of the nipple sphincter, not subject the nipples to excessive compression, and not cause irritation; create a vacuum and the duration of the sucking stroke in accordance with intrauder pressure and the rate of milk flow. Milking cups should fit teats of various sizes, not creep onto the udder and not pinch the upper mouth of the teat canal. They must be held on the udder without the use of a special device.
The milking machine should be easy to manufacture and maintain, reliable in operation, should not require manual adjustment during the milking process, and should provide the ability to conveniently visually monitor the flow of milk from the udder.
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Features of milking cattle
Milking is the process of obtaining milk from farm animals (cows, goats, sheep, mares, etc.).
In a lactating cow, milk is formed in the udder in the intervals between milkings and is retained in it due to the capillarity of the mammary gland, the special structure of the ducts and the presence of sphincters (compressor muscles) in the nipples. Milking is carried out thanks to complex milk ejection reflexes. Under the influence of irritation of the nerve endings of the mammary gland during milking, the sphincters of the nipples relax, the smooth muscles of the udder contract, and milk is removed from the tanks and large excretory ducts. After a few seconds, under the influence of the hormone oxytocin, the stellate cells around the alveoli contract, the alveoli shrink, and the milk from them passes into the ducts and cisterns. However, even after careful milking, a certain amount (10-15%) of milk (residual milk) with a fat content of 9-12% remains in the udder.
Over time, lactating cows develop conditioned reflexes of milk release to the environment. The noise of the engine of the milking machine, the appearance of the milkmaid, and other conditioned stimuli cause compression of the alveoli and the release of a hormone from the pituitary gland, as in the normal process of milking, unusual stimuli (sharp noise, change in the usual environment, etc.) can inhibit the milk ejection reflex. Therefore, when milking, it is important to maintain silence and maintain the established order.
The frequency of milking is set so that in the intervals between milkings the udder is filled with milk and milk formation is not inhibited. Typically cows are milked 2-3 times a day, highly productive and fresh cows 3-4 times. Before starting, the number of milkings is gradually reduced.
Cows are milked two or three times during the day. In some cases, when milking three times, 10% more milk is obtained than when milking twice. But this is typical for cows with a small udder capacity. In cows with a large udder capacity, milk yield does not increase in such cases. When the number of milkings is reduced from three to two, labor costs are reduced by 25-30%.
Compliance with the rules of milking technique helps to obtain maximum milk yield. The milking process consists of the main process and auxiliary operations. The operator does not directly participate in the main process of milking milk from the udder of cows using the machine. Auxiliary operations are divided into preparatory and final, which are performed by the operator on non-automated installations.
There are six preparatory operations: the operator moves with the milking machine to the next cow, washing the udder with warm water at 40-45 ° C, wiping it with a towel, massaging the udder, milking the first streams of milk and putting milking cups on the teats. There are also six final operations: the operator goes to the cow, machine milking, disconnecting and removing teat cups from the teats, monitoring the condition of the udder, draining the milk.
Udder massage has a particularly beneficial effect on the completeness of milking and the fat content in milk, which increases milk yield by 8-12% and the fat content in milk by up to 1%. So, the first portions of milk contain 0.5-0.7% fat, and the last -8-12%.
The health of a cow largely determines its productivity. For example, with tuberculosis, the milk yield of cows decreases by 20-35% compared to healthy animals, and with brucellosis - by 40-60%. Mastitis, diseases of the limbs, diseases of reproduction, and metabolism reduce milk yield by up to 20-50%.
Machine milking
When machine milking, the most favorable physiological conditions are created for the removal of milk from the udder: the machine simultaneously milks all four lobes of the udder.
On farms with tether housing, cows are milked in stalls, using milking machines with a milk line of the ADM-8 type or portable buckets AD-100a, DAS-2B. When using installations with a milk pipeline, the load per operator can be increased to 50 cows.
On farms with free-stall housing and free-stall housing on deep litter, cows are milked in machine-type installations with a lower milk line. To milk cows in these installations, farms are equipped with special milking parlors (Figure 1), which can be independent structures adjacent to the premises for keeping cows, or located under the same roof with them. At milking parlors, pre-milking areas are arranged, the dimensions of which depend on the number of animals in one section (at the rate of 2.5-3 m 2) per head.
If there are no suitable premises in the barns, then the construction of a new milking platform is necessary. Its size is determined depending on the number of dairy cows and the duration of milking.
To achieve continuity of the milking process and more complete milking, modern units offer mechanical udder massage with electronic control.
The nerve receptors of the skin of the udder are irritated through tactile influences, that is, when milking the first streams at the beginning of the process, test milking, washing the udder, manual massage, attaching glasses and when the teat rubber pulsates during milking. To achieve optimal stimulation, a specific combination of pre-operations must last for at least 60 seconds. Since all these operations are manual, it is necessary to reduce their time in order to achieve high labor productivity of milkers with automated milking processes. The resulting deficit in stimulation can only be compensated by increasing the stimulating effect of the pulsating teat rubber and the function of the stimulus is transferred to the machine. This occurs when using the ACE Pulse method (APF - alternative increase in pulsation frequency). Thanks to the interval increase in the pulsation frequency of the teat rubber to 200 double strokes per minute throughout the entire milking process, intense stimulation of the receptors is achieved.
This method allows, with the lowest technical costs, to distribute tactile stimulation throughout the entire milking period and make manual stimulation absolutely unnecessary at the beginning of milking. When using the APF method, a significant increase in milk yield in cows is achieved, compared to milking machines without machine or without sufficient manual stimulation. The research results are confirmed in practice by an increase in milk yield by 5 - 8%.
Recently, a lot of modern, economical equipment for milking cows has appeared on the market. An example is the Milk Master milking machine from De Laval. Used for tethered housing. The design basis takes into account the needs of both the cow and the milker.
Milking is controlled by the flow of milk coming from the cow. All cows are different. They require an individual approach. Milk Master starts working in the low vacuum phase with reverse pulsation. This gently stimulates the cow to begin milk production. As soon as the milk flow begins, the machine switches to the main milking phase mode with a normal level of vacuum and pulsation, so that the milking process takes place as quickly and efficiently as possible. The Milk Master display shows indicators of milk yield, milk flow speed or milking time. Four indicator lights show the individual milking phase. The red light on the top cover of the machine begins to flash slowly as soon as the cow has finished milking. Information about milk production and flow levels makes herd management more progressive. An unexpected drop in milk yield may be the first signal of heat or a symptom of a disease. Information read from the milk yield indicator is a powerful tool for monitoring the effectiveness of feeding changes at the beginning of lactation.
The automatic release device for the milking machine facilitates the milking process. This device is controlled by Milk Master. The red light starts flashing as soon as the milking unit is disconnected from the udder.
Selection and formation of groups of cows for milking on sites
Cows that meet the following requirements are suitable for milking cows on milking platforms:
They have a bathtub-shaped, cup-shaped and rounded udder shape, the bottom of the udder is flat, its distance to the floor should be no less than 45 and no more than 65 cm;
The length of the nipples is from 6 to 9 cm, the diameter in the middle part after milking is from 2 to 3.2 cm, the distance between the front nipples is from 6 to 20 cm, between the rear ones, and between the front and rear ones from 6 to 14 cm;
The udder quarters must be evenly developed - the permissible difference in the duration of milking of individual quarters is no more than 1 minute;
The duration of milking a cow is no more than 7 minutes;
The permissible volume of milk after milking should be no more than 200 mg, and no more than 100 ml from a separate quarter.
The “Tandem” installation can be recommended primarily for those farms where there is no herd selected in terms of milking time and milk production rate. At the same time, to achieve maximum productivity in the Herringbone installation, cows must be selected for milk production rate and productivity.
When transferring animals to milking in milking parlors from linear milking machines, it is necessary to accustom them. Cows are accustomed to the sounds of the milking parlor, the weight of the udder and other technological procedures.
Cows are selected into groups according to their physiological state: fresh (1-3 months after calving), first half of lactation (3-6 months), second half of lactation (6 or more months). Groups of queens are formed according to the duration of milking time and the rate of milk production. The order of movement of cows for milking should be organized taking into account their physiological state: first, fresh cows, then the first half of lactation and after the second half of lactation.
Machine milking technology
When machine milking cows, it is necessary to take into account the process of milk production, which is regulated by the nervous and humoral system of the animal, its conditioned and unconditioned reflexes.
The process of machine milking of cows includes preparing the milking machine and the udder of cows for milking, the milking process itself (putting on milking cups, monitoring the milking process, machine milking and removing milking cups).
On milking machines of the “Tandem” or “Herringbone” type, the udders are washed out of the hoses using a special sprayer. Along with washing, the udder is lightly massaged, which promotes a more active milk supply. Thanks to these actions, the cows become ready to produce milk, which is noticeable by the swelling of the udder nipples, which become more elastic and pink. If the milk release reflex does not occur after washing and wiping the udder, then the operator quickly performs a massage, clasping individual quarters of the udder with his fingers and stroking them down towards the nipples. In some cows, the milk letdown reflex is triggered only by teat massage. Before putting on the teat cups, one or two streams of milk are milked from each nipple. When milking the first streams, the operator determines the presence of an allowance of milk, the condition of the mammary gland, and frees the excretory channels from bacteria contained in large quantities in the first streams.
The first streams of milk are milked into a special mug with a removable plate or a dark strainer. This makes it possible to detect a cow’s disease with mastitis (the presence of flakes, blood, mucus and other changes in the milk). For this purpose, it is advisable to use the “Biotest-1” device designed by BelNIIZH, which is based on measuring the electrical conductivity of milk. You should not milk the first streams onto the floor, as the milk of sick cows can be a source of infection.
When milking on “Tandem” or “Herringbone” type installations, the first streams of milk are milked before the udder is washed and massaged. A cow that has swelling, redness, induration and sores on the udder and teat cannot be milked with a machine. It must be milked by hand into a separate bowl. After this, hands should be thoroughly washed and disinfected.
Wash and boil the towel used to wipe the udder. This cow is isolated from the general herd for treatment.
Having prepared the cow, the operator immediately turns on the machine and puts on the milking cups. To do this, opening the milk tap or lowering the clamp on the milk hose, he brings the device under the udder with one hand, and with the other, one after the other, puts the glass on the nipples. To avoid leaks, you need to lift the glass up and at the same time bend the milk tube so that air does not get sucked into the glass. Long-term air leaks reduce the vacuum in the main pipeline, which worsens the operating mode of other already operating devices. When the glasses are put on correctly, you won’t hear any hissing; they need to be put on in the following order: near back, far back, far front, near front.
When placed on the nipples, the operator takes the glasses with his right hand, with a large and index fingers remain free. With their help, the nipple is directed into the milking cup. After putting on the glasses, the operator must make sure that the machine is working properly and milk is being milked intensively, only then should he approach the preparation of the next cow.
Maintaining the sanitary condition of the milking machine and dairy equipment
Milking equipment is sanitized after each milking by performing the following operations:
Wash the outside of the milking machines with warm water from a sprayer, insert glasses into the milk heads and prepare all equipment for washing;
Rinse in circulation with a hot (60±50C) detergent solution to remove the protein-fat film;
Disinfect in order to destroy pathogenic microflora and reduce bacterial contamination;
Rinse with water to remove residual detergent and disinfectant solutions.
Circulation washing with detergent and disinfectant solutions is carried out within 10-15 minutes.
In addition to washing and disinfection, milking equipment should be periodically disassembled, washed and cleaned manually.
When performing circulation washing, it is necessary to disassemble the corner pipes, the milk collector, the milk counter - once a week, and the milking machines - once a month.
To prevent the formation of milkstone, washing with an alkaline detergent is alternated with an acidic one. In the absence of an acid detergent, milking equipment is washed once a week with 0.1-0.2% solutions of acids (hydrochloric, acetic or sulfuric) for 20-30 minutes.
It is necessary to strictly observe the concentration of detergents, disinfectants and the temperature of the water for washing milking equipment, since the use of increased concentrations, as well as very cold or hot water, leads to a change in the physical and chemical properties of rubber products and a decrease in the quality of milk.
Milk cooling baths, milk collection tanks and other containers are manually processed after each use in the following sequence:
a) rinse the inner surface with warm water to remove milk residues;
b) washed with a 0.5% washing solution at a temperature of 45-50ºС using brushes;
c) wash off the remaining cleaning solution with warm water;
d) disinfected with a disinfectant solution;
e) washed with tap water until the disinfectant is completely removed.
When using dezmol as a detergent, additional disinfection is not required.
At least once every two weeks, you should completely disassemble the milking machines, thoroughly wash and disinfect all its parts, paying special attention to the teat rubber. Rubber parts are checked for their further suitability, then kept for 30 minutes in a 1% washing solution at a temperature of 70-80 ° C, after which they are washed with brushes and brushes and rinsed with hot water.
The remaining parts, immersed in a bath with a hot 0.5% washing solution, are washed using brushes and brushes, then immersed in clean water at a temperature of 70-80°C for 20 minutes. After washing the parts, assemble the devices and pass 10 liters of hot disinfectant 0.1% solution through them.
Once every 6 months, all rubber parts in the devices are replaced with new ones, and the removed parts, after thorough disinfection and degreasing, are placed to “rest” in special devices.
When testing milking equipment, it is necessary to pay attention to all components of the milk line, the internal surfaces of which come into contact with milk: milk taps, pumps, intake hoses, which must be regularly disassembled and washed with detergent and disinfectant solutions using brushes.
Exposure to alkaline detergents may result in the formation of a white coating on the inner walls of the milk pipe. To remove it, the milk line is washed with a 0.2% solution of acetic or 0.15% solution of hydrochloric acid.
Igor Nikolaev
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The vitamin composition and taste have placed cow's milk on a pedestal. It is the most popular among the milk of other animals. It is not difficult to obtain it in large quantities both on a personal and industrial scale. But often in a herd one cow produces much less milk than the other.
The secrets are not only in hereditary factors and physiological abilities of the udder and the body. The interest of the cattle owner to carry out a set of milking activities is also important.
The appearance of milk in a cow is considered a complex physiological process. The udder receives useful substances, which form the basis of your favorite treat. And from the digestive system, nutrients enter the blood.
For example, for a cow to give a liter of milk, up to five hundred liters of blood must pass through its udder.
Thus, a lot depends on the circulatory system, which must work like a clock. The hormonal and nervous systems play an important role.
The udder is a mammary gland divided in the middle by a septum. The latter acts as a support for the right and left halves. They, in turn, are divided into quarters - front and back. Accordingly, there are four teats on the udder (rarely up to six). Milk is produced in many small sacs called alveoli. This is exactly the explanation for the question of where the cow gets her milk.
On the inside they are covered with secretory epithelium, which produces milk. The alveoli communicate through tubes with ducts flowing into the milk tank. It is connected to the nipples.
During lactation, the alveolar system changes. Such a complex process depends on external factors, including mastitis, differences in milk productivity and composition.
The epithelium connects the leading parts of milk from nutritional components supplied by the blood:
- proteins;
- fats;
- lactose.
During the connection process, all these components change. But vitamins, enzymes, hormones, and mineral salts reach the animal’s plasma from the blood in natural terms, as is. Their content may vary. For example, the calcium composition in milk is fourteen times higher than in blood plasma. The same can be said about phosphorus, only the number is ten. As for sodium, there is a smaller composition - the difference is seven times in favor of plasma.
During lactation, milk is produced in the udder without interruption:
- first it flows into the cavities of the alveoli;
- excreted through small ducts into large ones;
- tanks are filled.
The whole process takes up to half a day, and then the mammary gland ceases to be so active.
If a cow is not milked for more than sixteen hours, the pressure in the udder increases and milk secretion stops completely.
Not milking a cow even for the specified period means starting the process of absorption of milk components. Allowing omissions leads to a decrease in milk production; the animal simply gives less of it. The udder must be large enough so as not to overfill, the cow must be prepared for this.
Milking
Milking cattle representatives is a very responsible and complex process, as is the production of milk. The udder is full. If you place catheters into the nipples, you will notice large streams. But despite the intensity, less than half of the contents will be milked. A smaller part of a cow's milk is in the tanks before milking.
There are known cases when at the very beginning of milking a significant part of the milk was in the tanks. To get the rest, you need to compress the alveoli. It turns out that the first milk portions flow out of the tank quite easily. The cow makes no effort to leak it out and cannot even hold it back.
For full impact, you need to make an effort to compress the alveoli located in the nipples. In this case, a manual method or using milking equipment is used. They contain the bulk of the milk produced.
It is never possible to completely empty the udder. There is a little more than a liter of residual milk left there. It does not disappear, new arrivals join it and within a few days the milk is milked out.
If residual milk is considered a natural physiological phenomenon, then sometimes it does not completely empty the udder due to poor quality milking.
How does milking happen?
Milking is considered a reflex. To a certain extent, the flow of blood plays a role in the flow of milk. This is clear from the increase in udder temperature, it becomes hot, and the nipples become slightly enlarged.
Thus, the following components of the body are involved in milking:
- nervous system;
- endocrine glands (thyroid, posterior pituitary, stellate cells);
- breast muscles.
If you try to turn off the sensitive receptors of the mammary gland in laboratory conditions, the natural milking process is disrupted. Simply touching the nipples is pointless; they need to be squeezed carefully, since it is possible to reach the necessary receptors with a volitional squeeze.
The greatest impact should be on the base of the nipples. Experienced livestock breeders adapt to the process.
Based on experiments conducted, experts were able to prove that evenly squeezing the nipples one hundred times a minute gives excellent results.
Of course, this is a labor-intensive process, but the resulting product is worth it.
Ejection hormone
From talking about the number of nipple squeezes during milking, it’s worth moving on to the release hormone. This is oxytocin. Most of all, it is cultivated in the blood by the third minute from the beginning of the process. After just four or five minutes of milking, the hormone becomes inactive.
Therefore, the ability to obtain milk is directly related to the ability to use these reflexes.
An experienced housewife or owner of dairy cows should carry out all procedures promptly so as not to miss the period of action of oxytocin. It is desirable that the milking scheme be the same. In this way, it is possible to achieve continuity and fruitfulness of the milking process.
Razdoy
The measures taken to ensure high-quality feeding, maintenance and milking of calving cows are called milking. If the whole complex is carried out correctly, then high milk yields are obtained and the productive health of the animal is maintained.
When the calves appear, milking can begin. About two weeks after calving, the cow is milked up to five times a day. Then three times. This is especially true for young females, when it is necessary to achieve high levels of milk yield and. Although, for financial reasons, many farms are switching to double milking - in the morning and in the evening, since these purposes will require a reduction in costs.
Previously, it was believed that milk remained during milking. Then this misconception was debunked. It turned out that it is constantly being formed. A smaller part of a cow's milk is stored in the glandular cells themselves, and a slightly larger part is stored in the alveoli. Only the last “vessels” accumulate milk, which is inferior in fat content to the other.
It is the last drops of milk that are called cellular and the fattest. In general, the more filled the alveoli are, the lower this indicator becomes.
A smaller portion of milk is obtained from cows in the final stage of lactation. Even the smaller the gap between milkings, the lower the pressure in the udder. But the white nutrient liquid arrives faster and overall productivity also increases. A short period of milk storage in the udder contributes to an increase in fat content.
Experts have developed certain milking rules that all livestock farmers should learn:
- washing the udder with warm clean water;
- Massaging the udder stimulates milk flow. Before milking, first rub the right half, then the left. Then they do several squeezes, as if pushing the udder upward, as a calf does. Before completing the process, the udder is massaged again, as if driving milk out of the ducts;
- milking should take place at the same time, in a constant place;
- After the birth of the first calf, milking should occur up to four times a day at intervals of seven hours. This way it is possible to avoid pressure in the alveoli in a young cow;
- observance of the order of cows. In general, developed habits must be observed. The cow is very sensitive to any changes;
- a kind attitude towards the animal, so as not to create stressful situations. During milking, you should not scare her, shout at her or hit her.
Every diligent herd owner or newcomer to the agricultural industry is faced with the problem of choosing an animal. The latter need to remember a few rules that will help you buy a good-quality cow that brings good milk yield.
