Cattle breeding: Guidelines for laboratory and practical classes. Milk productivity of farm animals The uniformity of lactation is judged by the following indicators

The purpose of the lesson. To teach students how to record the milk production of cows, measure these indicators and use them in the assessment and selection in breeding work with cattle.

Content and methodology of the lesson. Milk is the cheapest and most complete livestock product. The milk productivity of cows depends on the breed, as well as on the conditions of feeding, maintenance and use. The process of formation and milking of milk from the mammary gland is called lactation, and the time during which animals produce milk is called the lactation period, the moment of cessation of milk production is called launch, and the time from launch to new birth is called the dry period.

A graphic representation of daily or monthly milk yields during lactation is called a lactation curve. The lactation curve is a line connecting the points of indicators of average daily or monthly milk yields by months of lactation. Months of lactation are laid horizontally, and average daily milk yields of each month are plotted vertically (Fig. 1).

Based on the data of control milk yields, the following is determined:

a) the highest daily milk yield (v.s.u.);

b) milk yield for each month of lactation;

c) average daily milk yield for each month;

Milk productivity of cows is characterized by quantitative and qualitative indicators. Quantitative indicators include milk yield per lactation, while qualitative indicators include the average content of fat and protein in milk.

Fig 1. Scheme of the lactation curve

Evaluation of boxes for milk production is carried out according to milk yield (kg) for the first 305 days of lactation, the average percentage of fat per lactation, milk protein (%), the amount of milk fat, averages for several lactations, lifetime productivity. Additional indicators for evaluation are:

1) uniformity of lactation;

2) lifetime milk yield - milk yield for the entire life of an animal;

3) milk flow rate;

4) the highest lactation;

5) shortened lactation for 90.180 days of lactation.

The uniformity of lactation can be determined by the coefficient of lactation constancy and by the highest daily milk yield. In the simplest case, the coefficient of lactation constancy is understood as the ratio of milk yield of a given month to the previous one, expressed as a percentage. The percentages obtained for 2, 3, 4, 5, 6, 7, 8, 9 months of lactation make it possible to establish the uniformity of the lactation of the animal. Depending on the value of productivity and the level of feeding of cows, the decrease in daily milk yield after reaching the maximum (2-3 months of lactation) ranges from 4-5 to 12-14% per month. Usually, in the last two months of lactation, milk yields fall by 30-50% compared to the previous month.

In some cases, the uniformity of lactation is determined by the formulas:

, (1)

where X is the coefficient of lactation constancy;

A - B - productivity for the first 70-180 days of lactation;

, (2)

where a is the actual milk yield for 305 days;

B - the highest daily milk yield;

P is the number of days of lactation.

The rate of milk flow is an indicator of the physiological properties of the udder. It is defined as the ratio of daily milk yield to milking time (expressed in kg/min).

In parallel with these indicators, the udder index is often used, i.e. the ratio of milk yields from the front and rear quarters of the udder expressed as a percentage. In practice, for this purpose, the ratio of the milk yield of the front quarters to the total milk yield, expressed as a percentage, is used. Accounting for milk productivity can be carried out by control milkings in the following periods: daily, ten days (once a decade), once a month, according to the highest daily milk yield, according to the sum of daily milk yields for three adjacent months using the Kalantar coefficient.

The percentage of fat is determined monthly, once a month due to two adjacent days. The average percentage of fat and protein in milk per lactation is determined by summing up one percent milk (product of milk yield per month by percentage of fat, protein) for each month and dividing this amount by the actual milk yield for 305 days.

For example: milk yield for the 1st month - 300 kg of milk with a fat content of 3.8%; milk yield for the 2nd month - 400 kg of milk with a fat content of 4.0%. Multiplying the milk yield per month by the average fat content in milk, we find the amount of one percent milk:

300x3.8 = 1140 (kg) 400x4.0 = 1600 (kg)

The amount of one percent milk for 2 months will be 2740 kg (1600 kg + 1140 kg). Dividing the amount of one percent milk (2740 kg) by the actual milk yield (300 kg + 400 kg = 700 kg), we get the average percentage of fat in cow's milk for two months 3.92%. The number of kilograms of milk fat is determined by dividing the amount of one percent milk by 100 (2740 kg: 100 = 27.4 kg).

In pedigree and commodity farms, account for milk productivity by control milkings, which are held once a month.

The milk yield of a cow on the days of control milkings will be:

5.01-10kg, 15.01-15kg, 25.01-15kg.

Therefore, milk yield per month will be 400 kg ((10 +15.+ 15) * 10 ~ 400 kg). If the control milking was carried out once a month, then the daily milk yield on the control day is multiplied by the number of days in the month and, thus, the cow's milk yield per month is obtained. Summing up the monthly milk yield, the productivity of a cow for lactation is obtained. Sometimes, in the absence of a full account of the productivity of an animal, the theoretical annual milk yield is calculated using the highest daily milk yield, multiplying it by a factor of 200.

For example: the highest daily milk yield of a cow is 15 kg, therefore, the productivity per lactation will be 3000 kg (15 kg x 200 = 3000 kg).

In some cases, the amount of milk yield for lactation can be determined by the method of prof. A.L. Kalantara.

Table 8 - Calculation of the theoretical annual milk yield (by the method of Professor A.A. Kalantar)

The amount of control milk yields	Multiplied by a factor
For 1 + 2 + 3rd months

According to A.A. Kalantar, milk yield per lactation is determined as follows.

Within three months, one control milking is carried out. The sum of milk yields for three control milkings is multiplied by the Kalantar coefficient. The value of these coefficients depends on the months of lactation during which control milkings were made, for example: control milkings were made for a cow at 3.4 and 5 months of lactation and received the following productivity:

3rd month of lactation, control day - 5.01, daily milk yield ~15kg;

4th month of lactation, control day - 5.02 - and - -12 kg;

5th month of lactation, control day - 5.05 - and - 10 kg;

Therefore, the milk yield of a cow per lactation will be 3330 kg (15 kg + 12 kg + 10 kg = 37 kg x coefficient 90-3330 kg).

Task 1. According to the cow's milk productivity card:

1) check the accuracy of determining milk yield for lactation according to ten-day control data;

2) check the accuracy of determining milk yield for lactation by control milkings carried out once a month;

3) check the accuracy of determining the theoretical annual milk yield by the highest daily milk yield and by the method of prof. A.A. Kalantara.

Table 9 - Vestochka, 45356, lactation, Simmental breed

Months of lactation	Actual milk yield, kg	Milk yield according to ten-day control data, kg				%fat per month	1% milk
			II decade	III decade

1. Milk yield of a cow for 305 days, kg ______________________________

2. Average % fat per lactation _______________________________

3. The amount of milk fat per lactation kg _________________

Using the calculation data, determine the amount of milk of basic fat content, kg _______________________________________________

Table 10 - Nickname Zorka 23492, Lactation 5 Simmental breed

lactation	Actual milk yield, kg	Daily milk yield per day control milking, kg	month, kg	per month

1. Milk of a cow for 305 days, south _________________________________

2. Average % fat per lactation _________________________________

3. The amount of milk fat for ________________________________

Table 11 - Cow productivity according to the highest daily milk yield

Name and number of the cow	Actual milk yield, kg	The highest daily milk yield, kg		Difference with actual milk yield, kg

Table 12 - Cow productivity calculated by the method of A.A. Kalantara

Average monthly milk yield according to control milkings for the following months of lactation		Theoretical annual milk yield, kg	Actual annual milk yield, kg	Difference from actual milk yield

Table 13 - The ratio of milk yield of this month to the previous one

Nickname, inv. No.											Milk yield for 305 days of lactation

where a is the actual milk yield for 305 days of lactation,

B - the highest daily milk yield,

P is the number of days of lactation.

Task 2.

1) using the average indicators of milk productivity of cows of different ages in the herd, determine the coefficients of conversion of milk yield from the 1st and 2nd lactation to the third and older.

2) calculate the milk yield of adult cows using the milk productivity of the same cows for the 1st and 2nd lactations and conversion factors. Compare estimated yield with actual yield. Enter the calculated indicators in table 16.

Table 14 - Milk yield of cows

Indicators
	1st lactation	2nd lactation	3rd lactation
Herd average (actual data)
Cow I: actual
settlement
Cow II: actual
settlement

For example: according to the grading data, the following productivity has developed in the herd: 1st lactation - 3000 kg, 2nd lactation - 3500 kg, 3rd lactation and older - 3900 kg. The transfer coefficient from the 1st lactation to the 3rd and older will be 3900: 3000 - 1.3; from 2nd to 3rd and older will be equal to 3900:3500 = 1.11.

Lactation in a cow is a difficult process at the level of physiology in the production of milk, which is created during the work of the nervous and humoral systems in the animal's body. Lactation is directly related to the overstrain function of the digestive system, as well as the lungs, heart and blood vessels. In this article, you can learn more about all the details of cow lactation.

Description

Lactation (derived from the Latin lacto - “milk content”, “milk feeding”) is the process of development and accumulation of the milk mixture in the udder of cattle female; excretion occurs during feeding or milking. At home, thanks to man, cows began to produce more milk and dairy products in general. Quality and quantity do not mean anything yet, because the most important factor is the impact of the environment on the cow's nutrition. Therefore, the name lactation period appeared, which implies a certain time interval for obtaining milk.

How many days does lactation last in cows?

Normal duration of lactation in cows occurs within 305 days. But this is not a constant indicator, since everything depends on the fertilization of the female. Ideally, if calving occurred at the same time after conception, which is about 1 year. In this case, lactation can last up to about 315 days, and the dry period can last up to 60 days.

Therefore, this stage is very individual, it all depends on the breed, the position of the cow, and, most importantly, on the content and nutrition.

The secretion of milky fluid is a reflex, since in principle it cannot be artificially caused, everything is natural. Milk arrives already at the time of delivery or before the day it should calve, but this happens very rarely. The mammary gland changes when the cow is still pregnant, that is, the fatty tissue of the udder is replaced by secretory alveoli, and after a certain time, the udder begins to grow.

Milk begins to decrease, the cow is not milked until the next birth. The mammary glands are in a period of rest, during which time the recovery process takes place, and then everything from the very beginning. Hormones take over the basic development of the udder, this is all seen during the first pregnancy. There are individuals in which the mammary glands can account for 3% of the total fat mass, there is a big load on the part of the heart and its system.

In the diet should be added drugs to increase milk production.

The lactation period has three phases.

Colostrum

This is the initial stage after calving, which can last from 7 to 10 days. Colostrum contains a lot of nutrients, such as protein, fats, various vitamins, trace elements and other nutrients. It also contains a high concentration of lactobacilli and other additional microorganisms useful for the functioning of digestion.

This is the very first food for the calf, thanks to which it develops immunity to the environment, and the opportunity to create additional positive bacteria for the digestive system. For the human diet, this is an unusual food, as it has an unpleasant and unusual taste. After the birth has passed, the cattle needs to recover, so for the first few days roughage is included in the diet, and after 4 or 5 days it can already be transferred to combined, wet or semi-moist food.

normal milk

It takes on a classic composition, a different texture and taste. In terms of duration, this phase takes from 190 to 280 days, the amount of milk always changes, there are no identical indicators. For the first months, a cow can produce up to 15 liters of milk per day, but then over time, the amount of milk fluid decreases.

When the colostrum has departed, the cow needs enhanced feeding.

This includes coarse, wet and semi-moist, concentrated foods.. You can also add root fruits and food based on dry nutrient mixtures - they increase lactation.

old milk

Formed at the end of the lactation period. May have a duration of 7 to 10 days. Leukocytes and proteins increase significantly, and acidity is much lower. This milky liquid is of very low quality, so it is not used in food production. At this stage, the cattle is transferred completely to dry food, where you can add vegetables and root crops.

A cow in a year can give milk from 9 to 10 months, despite the fact that 2-3 months before giving birth, she remains at rest. During this period, she rests, gaining strength for the birth of a calf. Bitter tastes predominate in milk, so milking is stopped.

Nutrition techniques during lactation

In order for the milk to be of high quality, the cow's udder must pass great amount blood, which contains nutrients enriched with additional vitamins. Therefore, a balanced and high-quality nutrition during the lactation curve is considered a huge guarantee. high performance cattle and long feeding of the calf. The cow is transferred to individual nutrition, that is, to a diet.

Consider several types of feed:

• wet food- the composition includes juicy food enriched with pieces of root fruits, or it can be all kinds of waste that is in the food industry;
• semi-moist food- this is a roughage based on herbs, which are preserved in an airtight container, it contains special concentrates and additives to increase the productivity of the animal;
• roughage- this is hay, which contains various field and meadow grasses;
• dry food mixtures- this includes special feed pellets, which include concentrated nutrients, where the basis is grass meal;
• concentrated feed- grain fruits, such as corn, millet and other crops;
• vegetable feed- fruits of vegetables, as well as root crops.

Before introducing this or that complementary food into the diet of an animal, it is necessary to take into account its weight and productive functions of the body, and, of course, age affects the amount of dairy products excreted. For every 100 kilograms there should be half a feed unit. If you do not give the right amount of feed, then the body of the cattle will be oppressed, that is, starvation will begin.

Feeding frequency

Experienced farmers and veterinarians agree that a lactating cow should be fed 3 times a day. This is the best option for significant thoroughbred horned cattle. If a cow is from a highly productive family, and she gives more than 5 thousand liters of milk in one year, then this nutrition will be very small. Therefore, complementary foods are added to the diet, which will provide 4 or 5 meals a day.

Remember to follow these tips to improve the absorption and effectiveness of groundbait:

• mix root vegetables with a mixture of succulent feed;
• at the end of milking, the cow should be given concentrated, dry or semi-moist food;
• Moisture-cured bait is needed in large quantities.

Types of milking machines

Classification of machines occurs according to the types of installed engines. They are divided into equipment with a dry motor and an engine in oil. The difference is that the blades of a dry motor are made of graphite material, which deteriorates very quickly, and when it works, it creates a lot of noise. Therefore, the price value is very low.

The oil-powered apparatus has blades made of a metallic material that move due to a special lubricant. There is almost no noise. Durable in use.

The milking machine is classified according to the principle of "smart action" and the characteristics of the working process.

• According to the types of installed glasses, which can include both one- and two-chamber glasses.
• According to the method of milking, use of two-stroke or three-stroke machines.
• By pump type- piston and centrifugal. The piston pump can be operated without a connected pulsator. Differs in the low price and simplicity in application. The pulsator-based pump works better and produces quality milking.
• Milk collection. Household plan model, where there is a convenient container that is removed and easily drains the milk. Thanks to advanced production, special tubes are available that are easy to connect to the tank itself.

How to choose?

Today, the world market is rich in various milking machines. They can be distinguished by several criteria - these are dimensions, equipment and power. When choosing this device, you should pay attention to how the collection of milk fluid will be carried out and how many cows can be connected to one device.

When a farmer chooses one or another device, it is necessary to build on certain indicators that are responsible for technical properties when installing.

The period during which milk is obtained from a cow: from the time of her calving to the launch of the dead wood is called lactation. The duration of the lactation period in cows with an annual calving is an average of 10 months. For comparison: in goats - 6; in sheep - 4; in mares - 8-10.

Milk production is expressed in milk yield. For this, the amount of milk milked per day is periodically measured or weighed.

Modern technologies for the production of milk with tethered content cows and milking them in the milking parlors allow to take into account the amount of milk yield and the quality of milk of each cow of the herd daily. And the use of special computer programs makes it possible to calculate the milk yield of a cow for any period of her lactation and life. This certainly makes it easier for breeders to evaluate cows as accurately as possible.

However, when animals of a dairy herd are tethered, control milkings are used - periodic accounting of the quantity and quality of milk: ten days (once every 10 days) or monthly (once a month). At the same time, milk yield from a cow per month is determined by calculation. With ten-day control, milk yield for the control day is multiplied by 10, while the sum of three such milk yields gives milk yield for a month of lactation. With monthly control, milk yield for the control day is multiplied by 30. Of course, such an assessment is inferior in accuracy to individual daily accounting of milk yield, but it allows you to evaluate and compare cows of a dairy herd with each other, and, therefore, select animals according to their own productivity.

The sum of milk yields for all months of lactation is the milk yield for the entire finished lactation. However, in Russia, for comparison of cows, an assessment was made according to the amount of milk yield for 305 days of lactation (normal duration of lactation). In the event that the duration of lactation is more than 305 days (extended), the milk yield is recalculated for normal lactation.

If a cow's lactation is shortened (less than 305 days), then it is evaluated by milk yield for the entire lactation without recalculation. Cows with a lactation duration of less than 240 days (8 months) are not evaluated.

The highest daily milk yield of a cow is usually reached in the second month of lactation. Considering that there is a high positive correlation between the highest daily milk yield and milk yield per lactation, in some cases, a rapid assessment of the milk production of cows is used. In this case, the highest daily milk yield is multiplied by a factor of 200 (with full feeding and uniform lactation, the highest daily milk yield is usually 1/200 of the milk yield for 305 days of lactation). This estimate is not accurate and is used as a preliminary one.

When assessing milk productivity, not only the quantity, but also the quality of milk is taken into account, i.e. its fat and protein content. milk samples for qualitative analysis herds are taken from each cow at least once a month for two adjacent days from each milk yield in proportion to its size. Based on the results of a monthly assessment of the quality of cow milk, the content of fat and protein in milk is calculated on average per lactation. To do this, determine the amount of one percent milk for each month according to the formula:

Amount of 1% milk per month (kg) =

Milk yield per month (kg) H percentage of fat (protein) in this milk yield.

Average percentage of fat (protein) per lactation =

To evaluate cows by the yield of milk fat or protein, the amount of fat (protein) per lactation in kilograms is determined by the formula:

Amount of fat (protein) per lactation (kg) =

The division by 100 is due to the fact that, by definition, 1% milk is such milk, 100 kg of which contains 1 kg of fat or protein.

According to the yield of milk fat, it is possible to compare cows of different milk fat and abundant milk content.

The amount of milk, milk fat, percentage of fat and protein in milk, if necessary, is determined not only for one completed lactation, but also for other periods (for a number of lactations, for the entire productive life of a cow, etc.).

Ceteris paribus, cows that are able to maintain milk yield at the highest daily level for a long time have the highest milk yield per lactation. This ability is revealed during the study of the nature of the course of lactation. The lactation curves show the peculiarity of the lactation activity of a cow most clearly. The lactation curve is a graphic representation of the course of lactation. When drawing a lactation curve, the months of lactation are laid off along the abscissa, and the average daily milk yield of each month is plotted along the ordinate. Features of the lactation curve depend on the individual properties of the cow, mainly on her tendency to milk and maintain high daily milk yields during lactation.

A.S. Emelyanov identified four types of cows according to the nature of lactation curves:

Type I - strong stable lactation activity. Such animals are well milked, significantly increasing the level of milk yield by the time the highest daily allowance is reached, they are able to long time maintain the level of productivity set by the milking and gradually reduce it by the last months of lactation.

Type II - strong, but unstable lactation activity, which is characterized by a two-peak lactation curve. Such cows are well milked, but after receiving the highest daily milk yield, their productivity decreases and rises again in the second half of lactation.

III type - high, but unstable lactation. Cows with such lactational activity are well milked, but are not capable of long-term retention of high milk yields. They decline quite rapidly throughout lactation.

IV type - stable low lactation. Such lactational activity is observed in cows that are not prone to milking, but at the same time are able to maintain the achieved level of productivity well during lactation.

Lactation curves of various types are shown in Figure 23.

Rice. 23

Taking into account the dependence of milk productivity on a number of paratypical factors, it should be noted that comparing cows by the nature of the course of lactation is advisable only if the animals are in the same conditions of feeding, keeping, with the same milk production technology, etc.

An individual assessment of cows is carried out in order to select animals and determine their purpose: breeding - new generations of animals are obtained from these cows; custom - to receive from them marketable products; production marriage - these animals are culled at the end of lactation.

Group accounting of milk productivity (by herd, farms of the district, region, etc.) is carried out in order to determine the efficiency of milk production in the specified group of animals. In group accounting, the milk yield per average annual cow is determined by the formula:

The average annual number of cows is determined by dividing the number of feeding days in the accounting year by 365 days.

In order to stimulate the improvement of the quality of milk produced in the farms for the regions, depending on the zoned breed of livestock, a basic level of fat percentage, and, recently, protein in cows' milk has been established. At the same time, payment for milk when it is sold is made not by its actual weight, but by weight in terms of basic fat content according to the formula:

For the Penza region, the basic fat content is 3.4%.

where: P 1 - milk yield for the first three months of lactation (1,2,3);

P 2 - milk yield for the next three months of lactation (4,5,6).

The coefficient of usefulness of lactation,%

In cows with equalized lactation, the lactation usefulness factor is 80% or more, with decreasing lactation - 50% or less.

Milk coefficient, kg

Economic indicators of milk production

- milk yield per average cow per calendar year. For various economic purposes, the annual milk yield per average annual cow of a herd, farm, and farm is often taken into account. This is done as follows:

1. Determine how much during the reporting year each cow was on the farm or how many feed days per cow; the number of foraging days of all cows is summed up, and then divided by 365 - this is the number of days in a year, and the average annual number of cows is obtained;

2. Set the number of heifers transferred to the composition of cows, and the calving time of each of them. Days after calving, during which each of the young cows was on the farm in the reporting year, are considered forage days; calculate the total number of forage days for all first-calf heifers transferred to the herd of heifers; take into account the number of culled or retired cows for various economic reasons;

3. The total number of forage days for all groups of cows without exception is summed up and divided by 365. Thus, the average number of forage cows per year is established;

Number of average annual cows, heads =

4. The gross milk yield obtained on the farm for the reporting year is divided by the number of average annual cows and the average milk yield per cow is obtained.

Calculation of milk yield per average annual cow is made according to the formula:

Milk yield per average annual cow, kg =

- feed costs (feed units) per 1 liter of milk is determined by the formula:

- cost of 1 liter of milk, rub.;

- milk production per 100 hectares of arable land, agricultural land, c(determines the level of animal husbandry and agriculture);

- profitability,%.

The milk productivity of cows varies over a very wide range (from 1,000 to 30,000 kg of milk or more). Even in the same climatic zone for the same calendar period, the average milk yield of cows in individual farms varies significantly. These differences are due to the complex interaction of breed and individual characteristics of animals, physiological state, feeding conditions, maintenance and intensity of use.

test questions

Define the concept of lactation. How does milk production (milk yield, fat, protein) change during lactation? What is the reason for this?

Factors affecting the duration of lactation

Service period and dry period, their significance.

What indicators are used when evaluating cows for milk production?

How is the average percentage of fat and protein in milk calculated?

Is there a relationship between the amount of milk yield, fat and protein in milk? Give examples.

How do indicators of milk productivity (milk yield, fat, protein) change throughout the entire period of economic use of a cow?

How does the milk productivity of a cow change under the influence of adverse factors external environment? Give examples.

Factors affecting the volume and efficiency of milk production.

Breeds of the dairy direction of productivity, their characteristics and distribution.