Purpose of the lesson. To study accounting methods and indicators for assessing the milk productivity of cows. Master the evaluation procedure and criteria for selecting cows based on milk productivity.
Equipment and visual aids. Breeding cow card (2-MOL), milk production log, control milking report (4-MOL).
An important biological feature of cattle is the ability of cows to give milk (lactate) for a long time.
Lactation is the period from the time a cow calves until she is allowed to dry off. The average duration of lactation is 305 days. During lactation, the amount of daily milk yield undergoes significant changes. After calving, daily milk yield increases, reaching a maximum at the end of the first – beginning of the second month, and, starting from the sixth month of lactation, milk yield begins to decrease (the fetus’s need for nutrients increases).
The time when milk production stops is called launch .
The period from the moment of launch until the next calving – dry period.
Service period– this is the time from calving to the fruitful insemination of the cow.
Calving period– time from one calving to another.
For the effective and economically most profitable use of cows, it is necessary that the intercalving period be equal to one year, that is, it is considered biologically feasible when a calf is produced from a cow every year. In this regard, the duration of the dry period should be no more than 60 days, lactation should be 305 days, and the service period should not exceed 80 days. The annual functional cycle of a dairy cow is shown in Figure 2.
Rice. 2 Optimal annual cycle of use of dairy cows.
During lactation, cows' milk yields vary. Each cow has its own individual changes in milk yield. All changes in the amount of milk produced by individual days and months can be presented in the form of a lactation curve (a graphical representation of milk yield per lactation). The nature of the lactation curve in cows is not the same. For some, it changes little during lactation, while for others it is subject to sudden changes. The lactation curve is determined by the level of milk production and the individual characteristics of the physiological state of cows, as well as the level of feeding and housing conditions. There are four types of cows based on the nature of lactation activity (Fig. 3):
1. High stable lactation. Cows of this type give a lot of milk and digest feed well. Characteristic of cows with a strong constitution and high milk productivity.
2. High unstable lactation activity falling after receiving the highest daily milk yield and rising again in the second half of lactation (two-peak type). Characteristic of constitutionally weak cows.
3. High, but unstable, falling quickly. After reaching the highest milk yield, it decreases sharply and during lactation it is low. Cows of this type have a weak cardiovascular system, not adapted to long-term work with high stress, such cows should be culled.
4. Sustained low lactation. Cows of this type have low milk yields and are subject to culling.
Cows are assessed by milk yield: per calendar or economic year, per lactation. The size of a cow's milk yield per lactation or year can be determined by daily recording and summing up the daily milk yield. But this is very labor-intensive. Therefore, a method of control milkings at certain intervals has been proposed: after 5, 10, 15, 20 and 30 days. When determining milk yield of cows based on control milkings, it is assumed that milk yield changes little between control days. It has been established that the shorter the interval between control milkings, the more accurately the milk yield can be determined. Milk yield for the period between control milkings is calculated by multiplying the amount of milk produced on the control day by the number of days in the period. The sum of milk yields for individual periods is the milk yield for lactation.
In breeding farms, milk yield is recorded every ten days (every 10 days), and in commercial farms – monthly. Under conditions of full feeding, the difference in milk yield for 305 days of lactation based on control milkings and taking into account daily milk yield is ± 1-1.5% for ten-day recording, and ± 3-4% for monthly recording. This error is insignificant, therefore, to facilitate accounting, control milkings are used instead of daily accounting.
When raising calves by suckling, the milk production of cows is taken into account in the following way: the calf is allowed to approach the cow and is allowed to suckle only from one half, usually the left, of the udder, and from the other (right) the milk is milked and measured. In this case, the amount of milk from the left and right half of the udder is always approximately the same. In this regard, the milk yield obtained from the right half of the udder is multiplied by two and thus the milk yield from the entire udder is determined. Using such control milkings, the lactation milk yield of cows of specialized meat breeds is determined.
The milk productivity of cows is assessed by the quantity and quality of milk obtained from them over a certain period of time.
At the same time, quantitative, qualitative and economic indicators are taken into account.
Quantitative indicators of milk productivity:
- milk yield for lactation indicating the number of days of lactation;
- milk yield for 305 days of lactation (determined when grading cows);
- milk yield per lactation period (by quarter, per month, etc.);
- milk yield for the best three lactations, lifetime milk yield (determined during cow grading);
- highest daily milk yield;
- gross milk yield (by group of cows, farm, holding);
Milk quality indicators:
- average percentage of fat and protein content in milk during lactation
Average percentage of fat content, (protein), % = ,
where: 1% milk - multiplying the milk yield of each month of lactation by the fat (protein) content in this month;
- amount of milk fat per lactation(305 days of lactation) is determined by the formula:
Amount of milk fat, (protein), kg,
It has been established that a cow’s milk yield during lactation depends approximately 25% on the highest daily milk yield and 75% on the nature of the decline in lactation activity. In cows of abundantly milking breeds, after reaching maximum milk yield, the decrease in the level of milk productivity in the subsequent months of lactation was 6%, in low-producing breeds - 9-12% per month. The nature of lactation activity is judged by its stability. To do this, determine coefficient of constancy (stability) of lactation.
In highly productive cows with pronounced high milk yields, the coefficient of lactation constancy reaches 90-99%, in cows with rapidly decreasing milk yields - 70-80%.
Lactation constancy rate, %
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).
Coefficient of complete lactation, %
In cows with leveled lactation, the coefficient of complete lactation is 80% or more, and in those with decreasing lactation, it is 50% or less.
Lactation (from Latin lactare - to give milk) is the process of formation, accumulation and secretion of milk by the mammary gland of a cow. The time during which an animal produces milk is the lactation period. On average it is ten months. A graphical representation of the lactation process is called a lactation curve. The lactation curve in cows is a “biological clock”, from which one can draw conclusions about the completeness of animal feeding, the state of complete feeding and other factors.
The nature of the lactation curve is influenced by the level of milk productivity of cows, feeding and housing conditions, fatness, frequency of milking, type of nervous activity, heredity, and individual characteristics. Based on the nature of the curve, there are on average three types of cows. Those that have persistent lactation activity, constantly low productivity, and those that give high milk yields after calving and then sharply reduce them.
The advantage is given to those cows whose milk yield curve gradually increases and decreases evenly, that is, those that have high lactation activity. These cows are distinguished by good health, longevity, better reproductive ability, and efficient use of feed with less physiological stress. The inheritance of constancy of lactation in first-calf heifers is 15.0%, in cows with second and third lactation it is about 20%.
A connection has been established between the persistence of milk yield in cows with different numbers of lactations. The genetic correlation between the persistence of milk yields I and II and I and III lactations is 0.6, and between II and III - 0.9. This suggests that the stability of milk productivity of cows in the first lactation differs in comparison with the indicators in the second and third lactation. According to Dutch researchers, first-calf cows (5,000 heads) had a productivity of 7,250 kg, and the average highest daily milk yield was 27.8 kg of milk. After the “peak” of milk yield, its daily decrease was 0.04 kg, and in the second and third lactations, respectively: 8650; 31.6; 0.07 and 9200; 38.9; 0.08.
In the state breeding plant "Oleksandrivka" of the Kyiv region on 48 first-calf cows of the Ukrainian black-and-white breed. Milk production was determined four times a month during the first three months after calving and three times in subsequent months of lactation. Milk productivity averaged 4287 kg (range from 2403 to 6087 kg), the mass fraction of fat in milk was 3.4%, protein - 3.16.
Based on the experiments conducted, it was established that for an objective assessment of the lactation activity of cows, it is advisable to use indicators of the ratio of milk yield for lactation to the highest milk yield for the month. The higher this indicator, the more stable the lactation curve. The average indicator of lactation stability is determined in the following way. The milk yield for each subsequent month, starting from the second and up to the eighth inclusive, is calculated as a percentage of the milk yield for the previous month.
The resulting indicators for each month are added and divided by their total number. This value characterizes the persistence of lactation. The optimal indicators of the persistence of lactation of cows are 95-97.
Note to dairy cattle owners.
The highest daily milk yield (“peak”) in cows is observed on average between 30-70 days after calving.
The approximate average distribution of milk yield in cows by month of lactation is as follows (in%): I - 12; II - 14; III - 13; IV - 12; V - 11; VI - 10; VII - 9; VIII - 8; IX - 6 and X - 5.
An increase in the “peak” milk yield by 0.5 kg leads to an increase in milk yield per lactation by 90-100 kg. If cows do not reach the calculated “peak”, the protein content of the ration should be checked, and if the lactation curve is unstable, the energy content should be checked.
It is optimal if, after the “peak” of milk yield, first-calf heifers reduce their milk yield by 0.2% per day, and full-aged cows by 0.3% (or 3% every 10 days). Cows with a high genetic productivity potential have a higher “peak” milk yield, reach it later and have a higher persistence of lactation. In general, the decrease in milk productivity of cows after the “peak” of milk production should be less than 8.0% per month for first-calf heifers and 10% of full-aged cows.
The milk production of cows at startup can be about half of the “peak” milk yield.
First-calf cows have a “peak” milk yield that is 25% less, and their lactation curve is more inclined and leveled compared to full-aged cows.
A decrease in milk yield in the middle and at the end of lactation (deviation from the standard curve) indicates an imbalance in animal diets in terms of basic nutrients during this period.
The decrease in fat content in milk during the period between calving and the “peak” of milk production is 0.15-0.30%.
The lowest protein content in milk is observed during the period of highest daily milk yield.
To determine the expected milk yield for a full lactation, you can use the highest daily milk yield. Usually it is 1/200 of the milk yield for 305 days of lactation. We find 1% milk: for this, the amount of milk for the control period x% fat for the same period. Next is the sum of 1% milk for all periods / on gross milk yield for the same periods = average % fat. The amount of milk fat and protein is found by dividing 1% milk/100. Coef. Milk production shows how much milk is produced per 100 kg of live weight. For dairy products - 800-1000 kg. The rate of milk production is determined by dividing the amount of milk produced by the time taken. It is determined for 2-3 months. lactation, in high-yielding women it is higher. Milk sold on farms is calculated based on basic fat content, which varies for regions of the country. (3.4%)
Types of lactation curves:
1) high, stable lactation. Such animals give a lot of milk and digest food well;
2) bimodal – strong but unstable lactation. It falls after receiving the highest milk yield and rises in the 2nd half.
3) high, but unstable, rapidly decreasing lactation. In such animals, s.s.s. not suitable for working with high voltage.
4) Steady, low lactation (low-productive animals).
The following indicators are used to characterize the curve:
1) coefficient of lactation constancy;
2) the ratio of milk yield for different periods of lactation;
3) stability of the lactation curve is the ratio of milk yield for the second 90-100 days to milk yield for the first 90-100 days of lactation, %.
7. Methodology for planning milk yield for a group of cows assigned to a milkmaid for the upcoming lactation.
Planning consists of several stages:
1) insemination of cows is planned 2 months later, on the third month after calving, counting the first month as the month of calving.
2) the calving date is set at 10 months after insemination, counting the 1st month of insemination.
3) based on the planned timing and taking the duration of lactation as 10 months, set the timing of the dry period and designate the month of the dry period with the letter C in the corresponding calendar months of the year.
4) Knowing the calving date and taking the duration of lactation as 10 months, the ordinal months of lactation for each cow are indicated. Before the first month of the dry period there will always be the 10th month of lactation, after the 2nd month of the dry period there will be 1 month of lactation. To simplify the calculation, it is assumed that if the launch date falls in the first half of the month, then the first month of the dry period will be this month, if in the 2nd half, then the next one.
5) in the absence of actual data for a specific herd, they are guided by the table “Coefficient of change in milk yield of cows with age.” Sustained milk yield for the next lactation is distributed by month of the year using the table “Change in average daily. cow milk yield by month lactation."
Milk formation is a complex reflex process that occurs in the mammary gland. It is regulated by both the nervous and humoral systems. Blood substances are used to produce milk.
The time from the cow's calving to the cessation of milk production is called the lactation period, and the cessation of milk production is called the start. The time from launch to the next calving is the dry period.
The milk productivity of cows is characterized by the quantity and quality of milk obtained over a certain period of time; for lactation, calendar year, and also for a number of lactations. In addition, in some cases the lifetime productivity of animals is taken into account.
Milk production assessment
Cows are assessed for milk productivity by milk yield (kg), fat content in milk (%) or amount of milk fat (kg) for 305 days of lactation or for a shortened completed lactation. With shortened lactation, the actual milk yield is taken into account and the duration of lactation is indicated in days. Control milking of cows is carried out at least once a month.
The average fat content of milk for the first 305 days of lactation or for a shortened lactation is determined based on the results of systematic determinations, which are carried out once a month. It is calculated by multiplying the percentage of fat in milk for each month by the monthly milk yield, the products are added (receiving the amount of one percent milk per lactation) and the amount is divided by the actual milk yield for the same months.
The amount of milk fat per lactation (kg) is determined by dividing the amount of one percent milk by 100.
First-calf heifers are assessed by milk yield for the completed lactation, cows of two calvings - by average productivity for two lactations, full-aged cows - by average productivity for any three lactations.
On commercial farms, in the absence of data for previous years, it is allowed to evaluate cows based on the last completed lactation.
The average milk fat content of cows when assessing their productivity for a series of lactation is calculated by summing the milk yield, expressed in one percent milk, for the lactations taken into account (305-day or shortened) and dividing this amount of one percent milk by the actual amount of milk produced for the same lactations.
To determine the properties of milk production in the 2nd-3rd months of lactation, control milking of cows is carried out during the day. During control milking, the amount of one-time milk yield (kg) and the time spent on each milking (min) are taken into account.
The average milk flow rate is determined in kg/min by dividing the amount of milk produced per day (kg) by the time spent (min). The results of monitoring the milk production properties of cows are recorded in a special sheet.
Lactation and lactation curve
The mammary gland, unlike other exocrine glands, functions inconsistently, but at certain periods determined by the physiological state of the cow. The period from calving to launch is called lactation.
During lactation, cows' milk yields vary. All changes in the amount of milk produced by individual days and months can be presented in the form of a lactation curve. The nature of the lactation curve of cows is not the same.
Lactation curves of cows at the beginning of lactation are characterized by increasing milk secretion. At the same time, the highest daily milk yield appears in the second or third months of lactation, and in low-productive ones - even in the first month. With the onset of pregnancy, milk secretion begins to rapidly decrease, and at the end of lactation it stops altogether.
Factors influencing milk production
The amount of milk that cows produce during lactation depends on hereditary and a number of other factors. The most important of them: breed characteristics, feeding and maintenance, age, dry period, age of first mating, weight, milking and some others
Heredity and breed characteristics determine the potential productive capabilities of animals. An animal of a particular breed has its own limit of productivity, determined by heredity. Therefore, the problem of creating highly productive breeds and improving less productive ones is always the focus of attention of breeders.
For example, the milk productivity of black-and-white animals averages 5000 kg, and the productivity of Caucasian brown cattle is only 3000-3500 kg.
The number and order of milking have a significant impact on milk productivity, especially in highly productive and fresh-calving cows. Milking and massage, while training the udder, simultaneously influence the intensification of the work of the cow’s entire body. When preparing a cow for milking, the central nervous system and pituitary gland are irritated. The latter releases the hormone oxytocin. The effect of the hormone (facilitation of the act of milking) lasts 4-5 minutes. Therefore, the milking speed has some influence on the daily milk yield and fat content in milk. It should also be borne in mind that with appropriate preparation of animals, transferring them from three to double milking does not cause a significant decrease in milk yield, and labor costs are noticeably reduced.
The milk productivity of cows also depends on their age, and until the fifth or sixth lactation, the milk yield of cows usually increases, then for several years they are maintained at approximately the same level, after which they decrease. There is a certain, hereditarily determined pattern in the nature of changes in daily milk yield during lactation. Gives a clear idea of this lactation curve. In dairy cattle breeding, three forms of the lactation curve are established: uniform, rhythmic, and rapidly declining. A uniform lactation curve is characterized by relative constancy, that is, an increase in daily milk yield for 3 months, and then a gradual, without any special disruptions, decrease. The specificity of the rhythmic lactation curve is that high milk yields alternate with lower ones for several days with an overall relatively uniform course of the curve. With a rapidly decreasing lactation curve, milk yield, having reached a maximum, then sharply decreases. Milk production is extremely influenced by feeding and housing of livestock. The level of feeding affects not only during the lactation period of cows, but also in the earlier period of their growth and development. If the animals received optimal diets with a sufficient content of protein, minerals, and microelements throughout the entire growing period, then their development proceeded normally, and in the first lactation such animals are able to produce a large amount of milk.
It is also known that with an increase in milk yield, the consumption of feed nutrients for production decreases. Therefore, the better the feeding of dairy cows, the cheaper the milk will be.
In all dairy cows, there is a positive relationship between live weight and their productivity. Shorter or longer periods of the dry period have an adverse effect on milk production in the upcoming lactation. Depending on the age, fatness and productivity of the cow, the normal dry period usually lasts 50-65 days. The level of milk productivity also depends on the duration of the service period. An average of 85 days is considered optimal (with fluctuations depending on the level of productivity and health of the cow). With a shortened service period, milk yield for a given lactation decreases.
The timing of calving can also affect the milk production of cows. In conditions of constant good feeding in the suburban area, relatively uniform calving of cows throughout the year is desirable. In areas more remote from the city, if good pastures are available, spring calving is advisable, since this allows for maximum use of cheap pasture feed. The level of milk production is also significantly influenced by the health status of cows. Normal productivity can only be demonstrated by completely healthy animals, characterized by good development of the whole organism and capable of producing offspring every year. Another condition for increasing the milk productivity of animals is the specialization of breeds in the dairy direction.
A fairly objective indicator of milk productivity is the milk production coefficient; it shows how much milk is produced per lactation per 100 kg of live weight.
KM = (Milk yield per lactation / live weight) *100
KM = (4880/500) * 100 = 976
In our herd, the average milk yield is 976
Calculation of milk base fat content:
M b = (M f * F f)/F b
M b - milk produced with actual fat content per year: per cow; for the whole herd.
F - actual fat content of milk
F b = 3.4% - basic fat content of milk
M b = (4880 * 3.7)/ 3.4 = 5278
Requirements for milk when accepted into dairies
According to GOST 13624-88, milk obtained from healthy cows is allowed for acceptance. This must be confirmed by a certificate of veterinary and sanitary welfare of the supplying farms, issued by a veterinary specialist no more than one month ago.
Milk must be free of foreign odors, unfrozen, homogeneous liquid, without flakes, white or slightly yellow in color, with a density of at least 1.027 g/cm3, and a temperature of no more than 10° C.
Milk cannot be accepted:
obtained in the first and last 7 days of lactation;
adulterated (skimmed, diluted with water or skim milk, with the addition of neutralizing and preservative components);
polluted;
with acidity above 22° T.
Table 5.1
Milk productivity of cows and milk sales to the state
Since the fat content of milk is 3.7%, which is 0.3% more than the base one, this allows us to obtain an additional amount of milk in terms of the base fat content.
HERITABILITY OF MILK PRODUCTIVITY DEPENDING ON BETA-LACTOGLOBULIN GENE POLYMORPHISM
Rachkova E.N.
The purpose of the study was to determine the heredity coefficient of milk productivity of first-calf cows depending on the polymorphism of the beta-lactoglobulin gene. We obtained high rates of heritability (h2< 0.40).
THE HERITABILITY OF MILK PRODUCTIVITY DEPENDING ON POLYMORPHISM GENE
BETA-LACTOGLOBULIN
The study of the study raised the determination of the coefficient of heredity of milk production of heifers depending on the gene polymorphism of beta-lactoglobulin. We have obtained high indicators of the degree of heritability (h2< 0.40).
UDC 636.2.034:636.2.082.2
*Tyulkin S.V. - Candidate of Agricultural Sciences, Head department; Zagidullin L.R. - Ph.D., Head. department; Rachkova E.N. - graduate student; Akhmetov T.M. - Doctor of Biological Sciences, Professor;
Kabirov G.F. - Doctor of Science, Professor, Head. Department *Tatar Interregional Veterinary Laboratory, Kazan Kazan State Academy of Veterinary Medicine named after N.E. Bauman
e-mail: [email protected]
Key words: cow, genotype, PCR, kappa-casein gene, lactation curve, milk production.
Key words: cow, genotype, PCR, gene of kappa-casein, lactation curve, milk yield.
It is well known that during lactation, milk production occurs unevenly. Under optimal feeding and housing conditions after calving, milk secretion usually increases (daily milk yield reaches a maximum in the first to third month after calving), and then the milk yield of cows decreases: slowly or intensively.
When studying the dynamics of cows' milk yield by month of lactation, four types of lactation activity are distinguished:
Type 1 - cows are characterized by high stable lactation activity, are physically strong, have high milk yields and are able to maintain an intense metabolism for a long time;
Type 2 - cows of this type
They are characterized by high, but little stable lactation activity, that is, milk yield falls after reaching maximum levels, and then rises again in the second half of lactation. In the figure, such lactation activity looks like a two-peak lactation curve. This lactation activity is characteristic of animals with a weakened constitution;
Type 3 - cows of this type have high, but not stable, rapidly declining lactation activity. Animals have, on average, low milk yields per lactation, as well as cardiovascular failure;
Type 4 - such animals are distinguished by low stable lactation
activity, they are predominantly low-dairy.
The dynamics of milk yield by month of lactation provides the most objective picture of milk yield throughout lactation. It makes it possible to see the peak productivity of cows during lactation and judge the ability of cows to milk.
All of the above speaks to the importance of studying lactation curves and the coefficient of lactation constancy in cows with different kappa-casein genotypes.
Material and methodology
research. The research was carried out at LLC “Serp i Molot” in the Vysokogorsk region and the Republic of Tatarstan on 219 first-calf cows of the Kholmogory breed of the Tatarstan type.
To determine the kappa-casein genotype, blood was collected from the animals. DNA was isolated from blood using the ammonia method. Testing of cattle for the kappa-casein gene (C5G3) was carried out using PCR-RFLP analysis and final detection of amplification and restriction products in a horizontal gel.
electrophoresis.
The nature of lactation curves was studied according to the method of A.S. Emelyanov in 1953, coefficient of constancy of lactation (LP) - according to Bigber in 1959, revised by A. A. Aksennikova in 1964. The calculation was carried out using the following formula:
LPL = (milk yield for 4, 5, 6 months of lactation / milk yield for 1, 2, 3 months of lactation) x 100;
The results obtained during scientific research were processed using the biometric method.
Own results
research. In cows of the Kholmogory breed of the Tatarstan type in Serp and Molot LLC, having the kappa-casein genotype AA and BB, the peak of the highest productivity (629 kg and 673 kg of milk, respectively) occurs in the 3rd month of lactation. In cows with the AB genotype, the highest productivity was observed in the 2nd month of lactation and amounted to 659 kg of milk (Table 1, this can be seen more clearly in Figure 1).
Table 1 - Dynamics of milk yield of cows with different kappa-casein genotypes during lactation
Lactation month Kappa-casein genotypes
(n=156) (n=63) (n=6)
I 507±17.2 554±19.4 559±18.4*
II 569±24.8 659±27.3* 635±23.5
III 629±27.1 634±20.1 673±24.9*
IV 571±21.6 601±20.6 609±25.2
V 544±27.8 590±24.5 603±21.8
VI 478±20.1 507±22.0 515±22.9
VII 476±18.7 479±21.7 481±25.9
VIII 464±20.6 444±20.4 486±23.1
IX 448±18.8 427±21.8 448±26.0
X 382±28.7 351±32.6 375±10.2
milk yield in 305 days 5068±163.1 5246±128.4 5384±96.3
lactation
Differences between BB, AB and AA: * - P<0,05
Lactation month
Figure 1 - Lactation curves of first-calf heifers with different genotypes
kappa-casein
The excess of the average monthly milk yield of cows with the BB genotype over the AA genotype was observed throughout almost the entire lactation.
Characterizing individual periods of lactation using the lactation curve, it can be noted that in the second phase of lactation, some cows progress more slowly, while others progress more quickly.
decreased milk secretion. An objective indicator characterizing
stability and smoothness of lactation curves is the coefficient
collapsibility. We determined the value of the decline coefficient from the second to the fifth month of lactation (Table 2).
Table 2 - Characteristics of lactation curves of cows with different kappa-casein genotypes
Kappa-casein genotype n Coefficient of decline in lactation curve, % Coefficient of lactation constancy
AA 156 4.59 93.4
AB 63 11.69 91.9
BB 6 5.31 92.5
According to the data obtained, a smoother and more leveled lactation curve is observed in cows with homozygous kappa-casein genotypes AA and BB. The coefficient of decline in the lactation curve from the second to the fifth month of lactation in cows of these groups was 4.59 and 5.31%, respectively, while in cows with the AB genotype it was higher by 7.10 and 6.38%, respectively.
An objective indicator
characterizing the degree of constancy of the lactation curve is
coefficient of constancy of lactation (LP). All groups of animals are characterized by high rates of lactation constancy (91.9 - 93.4%).
The nature of lactation activity in cows with different kappa-casein genotypes has been studied by other researchers.
Black-and-white cows with the kappa-casein AA genotype had a more stable and smooth lactation during the autumn calving season, while animals with the AB genotype had a more stable and smooth lactation during the spring calving season.
In addition, there was a tendency towards superior milk productivity of cows with the kappa-casein AB genotype over 305 days of lactation, both during the spring and autumn calving seasons.
A smoother and more leveled lactation curve is observed in black-and-white cows with homozygous kappa-casein genotypes AA and BB. The coefficient of decline in the lactation curve from the second to the fifth month of lactation in cows of these groups was 7.76 and 9.40%, respectively, while in cows with the AB genotype it was higher by 4.3-5.9% and reached 13. 67%. At the same time, cows with the AA genotype (3.95) and with the BB genotype (3.86) had the highest indicators of the coefficient of lactation constancy. The coefficient of lactation constancy in cows with the AB genotype is slightly lower and amounted to 3.58. Minor differences between animals of different genotypes showed, in general, evenness and constancy
lactation curves.
The coefficient of lactation constancy (LP) of all studied groups of red-and-white cows with different kappa-casein genotypes is at a high level. However, the highest LP was observed in first-calf heifers with the AB genotype, which indicates greater stability of their lactation. In second place in terms of this indicator are heifers with the BB genotype. Calculation of the coefficient of lactation decline from the 2nd to the 5th month showed that heifers with the BB genotype had a lower decline rate during this period; animals with the AB and AA genotypes were in second and third place, respectively.
The highest milk yields by month of lactation in first-time heifers of the Black-and-White breed with different kappa-casein genotypes were identified in the following sequence BB>AB>AA, and the lactation curves of the experimental animals belonged to type 1 according to the classification of Emelyanov A.S. .
Conclusion. Thus, the conducted studies showed that the analyzed animals, having different genotypes of kappa-casein, belong to types I and 2 of lactation activity, characterized by a high stable and gradually decreasing lactation curve. In addition, there was a tendency towards superior milk productivity
cows with the kappa-casein BB genotype throughout almost the entire lactation. Our results
researchers on the lactation activity of cows with different kappa-casein genotypes are consistent with the results of other scientists. Analysis of the data obtained suggests that the nature of lactation compares favorably with animals of the black-and-white, red-and-white and Kholmogory Tatarstan type, which carry the B allele of the kappa-casein gene in their genome.
LITERATURE:
1. Aksennikova, A.D. Determination of the constancy of lactation / A. D. Aksennikova // Bulletin of Agricultural Science. -1963. - No. 3. - P. 15-18.
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TYPES OF LACTATION CURVES AND LACTATION CONSISTENCY COEFFICIENT IN COWS WITH DIFFERENT KAPPA-CASEIN GENOTYPES
Tyulkin S.V., Zagidullin L.R., Rachkova E.N., Akhmetov T.M., Kabirov G.F.
In this work, the nature of lactation activity in cows of the Kholmogory breed of the Tatarstan type with different kappa-casein genotypes was studied. Studies have shown that, compared with analogues with the AA genotype of kappa-casein, the highest monthly milk yields are in animals with the AB and BB genotypes. All animals with different kappa-casein genotypes have fairly high lactation constancy coefficients of 91.9-93.4. Our research results are similar to the results of other scientists.
TYPES OF LACTATION CURVES AND COEFFICIENT OF PERSISTENCE OF LACTATION IN COWS WITH DIFFERENT GENOTYPES OF KAPPA-CASEIN
Tyulkin S.V., Zagidullin L.R., Rachkova E.N., Akhmetov T.M., Kabirov G.F.
In this study, we studied the nature of activities for lactation in cows of Kholmogorskaya breed the Tatarstan type with different genotypes of kappa-casein. Studies have shown that in comparison with analogues with the AA genotype of kappa-casein greatest monthly milk yield in animals with genotype AB and BB. In all animals with different genotypes of kappa-casein is quite high coefficients of persistence for lactation 91.9-93.4. The results of our research are similar to the results of other scientists.
UDC 636:637.12.04.07:637.12.6 TECHNOLOGICAL PROPERTIES OF GOAT'S MILK
Fatikhov A.G. - graduate student; Khaertdinov R.A. - Doctor of Biological Sciences, Professor, Head. Department of Kazan State Academy of Veterinary Medicine named after N.E. Bauman
e-mail: [email protected]
Key words: goat's, cow's, sheep's milk, coagulability, heat resistance. Key words: goat, cows, sheep milk, coagulation, thermal resistance.
Currently, goat milk and products made from this raw material are in great demand among the population. The distribution network mainly supplies pasteurized drinking goat milk, and its processed products: yogurt, kefir, curdled milk, cottage cheese and cheese are completely in short supply. This is explained by the fact that in our country dairy goat farming has just begun to develop and there are very few enterprises processing goat milk. For example, 30 thousand goats are bred in Tatarstan, but in the republic
Not a single dairy enterprise has mastered the processing of goat milk, so the bulk of goat milk is supplied for deep processing to the Sernur cheese plant in the Republic of Mari El. Only a small part of goat milk is sold on the Agroprompark Kazan market in the form of a natural whole product. An obstacle to the widespread introduction of deep processing of goat milk at dairy enterprises is the need to install specialized equipment to
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