First-calf Heifers Research Articles

Residual feed intake measured as replacement heifers is indicative of residual feed intake measured as mature cows

This study aimed to quantify the relationship between residual feed intake (RFI) measured in 500 heifers and subsequently as mid-gestation cows at the Roy Berg Kinsella Research Station (KIN; n=227) and Lacombe Research and Development Centre (LRDC; n=273). Heifers were initially tested for RFI adjusted for end of test rib fat (RFIfat) at 8-12 mo of age and then again as 3-yr old first-calf heifers at KIN and as 4-13 yr old cows at LRDC. Heifer RFIfat measured in drylot on a forage diet was associated (R2 >0.53; P < 0.001) with RFIfat measured again as older cows. Each 1 kg DM d-1 change in heifer RFIfat equaled 0.48±0.10 and 0.75±0.19 kg DM d-1 change in cow RFIfat for KIN and LRDC, respectively. Linear effects were also reported for RFIfat component traits, where DMI (P<0.001), ADG (P<0.060), mid-test metabolic weight (P<0.001) and end of test rib fat (P<0.001) measured as heifers were related when measured again as older cows. In addition, the linear effects of heifer RFIfat on cow RFIfat were constant across cow age groups from 4-10 yr of age. These results show that selection for RFI in heifers will result in cows that are also more feed efficient.

Impact of diferent types of selection on the milk productivity of Kostroma breed cows

The article studies the influence of homogeneous and heterogeneous selection on the milk productivity of first-calf cows (milk yield, fat and protein content in milk). The object of research is cattle of the Kostroma breed. The research methods were zootechnical, population-genetic and analytical using computer programs IAS “SELEX” Multifarm and BON-MilkRegion. The modern cattle breeding base in the Kostroma region is represented by three breeding plants and two breeding reproducers. In 2022, the Karavaevo Breeding Farm JSC received 9,297 kg of milk per cow, the Minskoe LLC pedigree reproducer received 7,371 kg of milk, and the Rodina collective farm, Gridino and Agrofirma Planet LLC received more 6000 kg of milk. Record milk yields reach 15,000 kg of milk or more in 305 days of lactation. The following lines have been identified as promising in the Kostroma breed: lines Ladka 2537 and Kursa 3722, related groups Master 106902, Meridian 90927 and Concentrate 106157. To improve the productive qualities of dairy cattle, it is necessary to use both intraline selection and cross-lines, taking into account their compatibility. In breeding farms, using homogeneous selection, high productivity indicators were obtained: in terms of milk yield - from first-calf heifers of the related groups Laird, Concentrate and Meridian, in terms of fat and protein content in milk - Laird and Ladka. With heterogeneous selection, the best combinations were identified across farms.

EXTERIOR FEATURES OF COWS OF DIFFERENT BREEDS AND INTERBREED TYPES

The purpose of the research was to determine the features of the exterior of first-calf heifers of different breeds, interbreed types and the influence of conditional blood by improving breeds. The exterior was evaluated in the herd of dairy cattle of the "Rosiya" breeding farm of the Donetsk region of 111 first-calf heifers Angler (AN), 28 – Red Danish (RD), 2034 – Ukrainian Red Dairy (URD), 69 – Ukrainian Black-and-White Dairy (UBWD) and 16 – Holstein (H) breeds by the methods of instrumental (10 measurements), visual (10 linear descriptive signs of type) assessment and calculation of body structure indices. Among the URD, 700 animals are classified as fat-milk (FRD) and 1334 – to holsteinized (HRD) interbreed types. A significant level of interbreeding differentiation of first-calf heifers was established based on the evaluated external features. In the first-calf heifers of the H, UBWD and URD breeds, better development in height, chest and rump, as well as a general improvement in body structure, was noted. The first-calf heifers of the AN and RD breeds are characterized by the largest diameters of the length of the body and the smallest - the circumference of the shin. According to the exterior, two identical clusters of breeds and types are defined. The first includes animals of AN, RD breeds and FRD, the second – first-calf heifers of H, UBWD and HRD. The use of the H breed in crossbreeding shifts the proportions of the cow's exterior in the direction of increased height, long legs, relative narrow-chested, lowness, eyrisomia, and RD and AN – in the direction of stretched, bony, massive and overgrown. At the same time, the interbreed differentiation into quality groups according to the exterior and milk yield of HRD and FRD within a single URD exceeds in many cases the interbreed difference of the Holstein cluster (URD, UBWD, H). It was established by the analysis of variance that breed affiliation determines 0.3...7.5% of the total phenotypic variability of the exterior of first-calf heifers, and conditional blood by the H breed – 1.7...56.2%. Conditional blood by the H breed shows a direct reliable relationship with height at the withers (r = 66.0 ± 1.57%), rump (63.1 ± 1.62%), depth (22.4 ± 2.03%) and girth of the chest (42.7 ± 1.89%), width of buttocks (28.6 ± 2.00%), length of rump (21.2 ± 2.13%) and circumference of the shin (33.3 ± 1.97%). The width of the chest increases with an increase in conditional blood in the AN breed (15.0 ± 2.06%), and the length of body - in the RD breed (12.5 ± 2.07%). The established (correlation analysis) level and direction of the relative variability of conditional blood for improving breeds with exterior and milking traits confirms the expediency and perspective of using the H gene pool and the impracticality of further use of AN, RD and FRD.

Udder characteristics of inbred and outbred first-calf heifers

Udder characteristics of inbred and outbred first-calf heifers

Milk productivity of first-calf heifers of Holstein breed depending on their genealogical lines origin

Holstein breed, which was bred in the USA and Canada has gained worldwide popularity because it has the most necessary traits for dairy farming on an industrial scale. In our country, this breed has recently been widely used to improve native domestic dairy breeds, for example, Black-and-White and Kholmogory, etc., which are well adapted to local conditions of housing and feeding. One of the widespread breed improvement methods in modern cattle breeding is line breeding. Using this method, breeders and milk producers can increase the productivity of their milking herd in a signifi cantly short period of time, ensuring growth in the economy of milk production. The purpose of the work was to study the milk productivity of fi rst-calf heifers of Holstein breed depending on their genealogical lines origin. The research was carried out at Kaluzhskaya Niva LLC in the Kaluga region, which is a specialized livestock enterprise for breeding dairy cattle. The farm is engaged in breeding cattle of Holstein breed and has the status of a breeding farm for this breed. The fi rst-calf heifers of Holstein breed were the object of the study with completed the first lactation. The total number of experimental animals was 40 animals, which were divided into two groups taking into account their genealogical lines origin. The 1st group included fi rstcalf heifers belonging to the line Wes Back Ideal 1013415 (n=24) and the 2nd group to the line Refl ection Sovereign 198998 (n=16). It was established on base the analysis of the data obtained that fi rst-calf heifers of the line Wes Back Ideal 1013415 with a higher daily milk yield had a minimum milking time and a high intensity of milk ejection. In terms of milk ejection intensity they were ahead of their herdmates from the line Refl ection Sovereign 198998 and the herd average by 0.23 and 0.09 kg/min, respectively (p > 0.05). Thus, to increase milk yield, fat content and protein content of cows Holstein breed, it is necessary to use more widely the sperm of sires of the line Wes Back Ideal 1013415. At the same time, use cows with the most suitable udder (bowl-shaped udder) for robotic milking.

Colostrum Replacement and Serum IgG Concentrations in Beef Calves Delivered by Elective Cesarean Section.

Assistance during calving and cesarean section (C-section) are important risk factors for the failure of transfer of passive immunity (FTPI) in beef calves, which increases the risk of morbidity and mortality in beef calves during the preweaning period. Colostrum replacement recommendations for beef calves, and especially for those delivered by C-section, are unavailable. The objective of this study was to determine whether or not colostrum replacement or supplementation with a commercially available product could increase serum IgG concentrations in beef calves delivered by elective C-section, compared to beef calves that nursed colostrum naturally. An elective C-section was performed in 32 pregnant beef cows and first-calf heifers. Immediately after delivery, newborn calves were randomly assigned to one of three different treatment groups. Group A calves (n = 7) were fed one packet of a commercial colostrum replacer (CR) product providing 60 g of IgG within 30 min of life. A second packet of the same CR was fed at 6 h of life. Group B calves (n = 13) were fed the same CR at the same frequency as group A; however, these calves were reunited with their dams after the second CR feeding to allow additional nursing of maternal colostrum. Group C calves (n = 12) were united with their dams immediately after surgery without colostrum intervention. Serum IgG levels at 48 h of life were greater in group C calves and in calves born to multiparous cows. Based on the results of this study, neither colostrum replacement nor supplementation result in higher serum IgG concentrations in beef calves delivered by elective C-section compared with natural nursing.

Some aspects of the relationship between the morphology of the ovaries and the exterior of first-calf heifers of the Middle Amur Region

The tie between the ovarian morphology and the exterior of 113 local black-and-white first-Calving heifers and the cross-breeds of different blood relationship with the Holstein bulls has been studied for the first time. The size of this tie varied from r = 0.01 to r = 0.22. And by this the tie of right-side ovary was stronger (r = from 0.06 to 0.22), of left-side – (r = from 0.01 to 0.09). The gynaecologist inspection of sexual organs of 96 cows, being selected visually, for the insemination by signs of heat and sexual behavior exposed the presence of the follicle of before-ovulation ripeness in the ovaries of 42.7% of animals (+++; ++++).

POLYMORPHISM OF LIPID METABOLISM GENES IN TATARSTAN-TYPE COWS

POLYMORPHISM OF LIPID METABOLISM GENES IN TATARSTAN-TYPE COWS

Delivery season and milk yield of first-calf heifers

Delivery season and milk yield of first-calf heifers

ВЛИЯНИЕ ЖИВОЙ МАССЫ МОЛОДНЯКА НА ПОСЛЕДУЮЩУЮ МОЛОЧНУЮ ПРОДУКТИВНОСТЬ ПЕРВОТЕЛОК В РАЗНЫХ КЛИМАТИЧЕСКИХ ПОЯСАХ РОССИЙСКОЙ ФЕДЕРАЦИИ

The purpose of research is to study the effect of live weight of heifers at the age of 6 months on their subsequent milk production. Objectives: to study the growth rate of heifers with different live weights at 6 months; to assess the level of milk productivity (milk yield, mass fraction of fat and protein, amount of milk fat and protein) in first-calf heifers with different live weights at 6 months. The study included more than 25 thousand first-time Holstein heifers of the same genotypes (lines), bred in four climatic zones co-vering the territory of the Russian Federation. These zones include subtropical, temperate continental, extreme continental and arctic climates. The regions of the Far North with the most severe and cold climate, unsuitable for breeding Holstein dairy cattle, were not taken into account. Data from the Selex information system were used for the analysis. Statistical processing of the obtained data was carried out on the basis of generally accepted methods of variation statistics (using MS Excel). The reliability of the difference bet¬ween the compared values was determined using the significance criterion according to the Student's table. It was found that the live weight of calves at 6 months has a certain influence on the subsequent milk productivity of first-calf heifers. However, the optimal live weight varies depending on the climatic zone. Thus, in a subtropical climate, the optimal live weight is more than 175 kg; in a temperate continental climate – more than 185; in a sharp continental climate – less than 166; in a harsh arctic climate – over 200 kg. These results make it possible to optimize the breeding process and ensure maximum milk production in different climatic conditions.

Frequency of occurrence of k-casein genotypes and their effect on the milk productivity of Kholmogory cows

To increase the volume of domestic dairy products, it is necessary to use modern breeding methods and select animals with high genetic potential. To determine the genetic potential of animals, molecular genetic markers are used, which make it possible to study how a specific genetic variant or combination of genes affects the desired trait. The purpose of the study is to identify the frequency of occurrence of allelic variants of the kappa-casein gene (CSN3) in Kholmogory cows and their relationship with milk production. The object of the study is 195 cows. To determine the genotypes of kappa-casein, the method of polymerase chain reaction of restriction fragment length polymorphism was used. The research was carried out in 2023 on the basis of JSC Kholmogorsky Breeding Plant (Arkhangelsk region). Results: in the studied herd, allele A of the kappacasein gene dominates – 80 %, respectively, allele B was 20 %. The predominant genotype is AA – 63.08 % (n = 123), the less common genotype AB is 33.33 % (n = 65), the least common genotype is BB – 3.59 % (n = 7). To assess milk productivity and milk quality in cows with different CSN3 genotypes, productivity indicators for the last completed lactation were compared. The total number of cows with completed lactation in the study sample was 130 heads, of which: 37 cows were first-calf heifers, 6 cows in the second lactation and 87 cows in the third or more lactation. In total, according to the comparison results, cows with the BB genotype had the highest indicators: milk yield – 6916±275 kg, mass fraction of fat – 4.14±0.22 %, mass fraction of protein – 3.16±0.07 %, amount of milk fat – 286±19 kg, amount of milk protein – 219±12 kg. Thus, the desired genotype for the CSN3 gene is BB. At the moment, there are very few carriers of this gene, so it is necessary to carry out selection and breeding work aimed at increasing their numbers.

Использование геномной оценки в совершенствовании продуктивных качеств коров голштинской породы

Abstract. Purpose of the study is analysis of productive and reproductive qualities of the Holstein cattle of the Tyumen region in comparison with the leading American enterprises using genomic selection. Materials and methods. Zootechnical, statistical and economic methods were used. As part of the work, the tasks were solved to consider the growth and development of replacement young animals; the main indicators of reproduction of heifers and cows of the main herd were analyzed; the milk productivity of cows and first-calf heifers was estimated according to the primary accounting data; a zootechnical assessment of sires used in the economy was carried out; the results of the genomic assessment were compared with the actual milk production. The scientific novelty of the work lies in the fact that genotyping was carried out in the conditions of a large industrial complex, because the use of genomic evaluation was not widely used in farms in the Russian Federation. Research results. The indicators of the intensity of growth of replacement young animals grown in the conditions of the Evika-Agro enterprise correspond to the world standards of the breed, and in some cases exceed them. The intensity of growing heifers allows for earlier insemination, which also contributes to early calving - 98% of animals calve up to 25 months of age. Estimates of milk production are largely consistent with those of advanced farms in the United States. “Evika-Agro” LLC uses outstanding sires from the world’s gene pool to improve economically useful traits, thereby accelerating the rate of selection. Analysis of the genomic assessment showed a significant discrepancy between the genetic basis of milk production and the actual level of milk production. This is most noticeable in the lifetime earnings index ($ 682) and the average increase in milk per lactation (916.2 kg) between the worst and best heifers in the sample.

Influence of genetic factors on productive traits of firstcalf heifers

The objects for the research were Holsteinized fi rst-calf heifers-daughters of sires with blood of 90 % or more of Holstein breed. In order to carry out the research three groups of first-calf heifers per 30 heads in each were formed. The 1st group included daughters of the sire Privelezh, the 2nd group included the daughters of the sire Alt Pilsner, and the 3rd group included the daughters of the sire Alt Tyson. The infl uence of sires on the productive traits of Holsteinized fi rst-calf heifers of Black-and-White breed was assessed under the conditions of the Petrovsky Agricultural Production Complex in the Bashmakovsky district of Penza region. It was revealed as a result of the research that the highest milk yield for 305 days of lactation was shown by the daughters of the sire Privelezh, which amounted to 9398 kg of milk and had a statistically signifi cant diff erence with the daughters of the sire Alt Pilsner – 3657 kg (Р > 0,999) and with the daughters of the sire Alt Tyson – 3542 kg (Р > 0,999). In terms of qualitative traits of milk productivity, the highest indicators were for fi rst-calf heifers of the 2nd and 3rd groups. For example, in terms of the mass fraction of fat the difference between cows of the 2nd and 1st groups was 0,16 abs.% (Р > 0,95). Diff erences were revealed between the 1st and 2nd groups by 0,04 abs.% (Р > 0,999). At the same time, due to higher milk yields animals of the 1st group exceeded their herdmates of the 2nd group in the yield of milk fat and protein by 127,92 kg (Р > 0,95) and 111,67 kg (Р > 0,999); 3rd group by 128,90 kg (Р > 0,999) and 109,08 kg (Р > 0,999), respectively. First-calf heifers of the 3rd group had the highest live weight (568,7 kg), the diff erence with their herdmates of the 1st group was 57,2 kg (Р > 0,999). Animals of the 2nd group exceeded the first group by 53,0 kg (Р > 0,999). The greatest variability in milk yield over 305 days of lactation was characterized by the 3rd group of cows (Cv=19,83 %) vice versa 17,45 and 18,92 % in the 1st and 2nd groups. First-calf heifers of the 1st group were distinguished by the greatest effi ciency and usefulness, although no significant differences were found between the groups. For example, per 1 kg of live weight, the Biological efficiency of a cow coefficient was 445,45 and the Cow biological f usefulness coefficient was 306,23.

Продуктивность коров при разной комбинации линий

The purpose of the study was to study the milk productivity of cows with different combinations of lines. The object of the study were first-calf cows of the black-and-white breed of the line Vis Back Aidiala 101341, Reflection Soveringa 198998, Montvik Chiefteina 95679. Cows obtained by intraline selection of the Aidial line have a high level of milk productivity, with milk yield of 5571 kg of milk, milk fat yield of 226 kg and protein yield of 171 kg, while significantly (P<0.05-0.01) superior to first-calf heifers, belonging to the Sovering line for 102 kg, 4 kg of fat and 4 kg of protein, and to the Chieftain line - for 259 kg of milk, 16 kg of fat and 11 kg of protein, respectively. When crossing the Ideal-Sovering lines, the highest milk yield is observed (5667 kg), with good milk fat content (4.01 %), high yield of milk fat (227 kg) and milk protein (172 kg). With the reverse cross Sovering-Idial, slightly lower milk productivity rates were obtained. When using bulls of the Aidial line on cows of the Governer line, high milk fat content (4.07 %) and milk fat yield (228 kg) were obtained, with average values of milk yield (5596 kg), protein mass fraction (3.01 %) and its yield (168 kg). Unsuccessful combinations of lines in both forward and reverse directions are crosses of the Idial and Chieftain lines. The descendants of such combinations have the lowest milk productivity. Thus, the use of line manufacturers R. Sovering and V.B. Idiala, both with intraline selection and interline combination, gives the best milk productivity indicators. Consequently, it is necessary to evaluate bulls according to the compatibility of lines; this has a great influence on the productivity of the offspring, since sires of the same line, when inseminating cows of the same lines, produce offspring of different productivity.

Продуктивность и биохимический профиль крови первотелок при повышении уровня кормления

High productivity and longevity of animals are the key challenges in modern dairy farming. In addition to high milk yields, first-calf heifers also have to increase their body weight. Due to their physiological characteristics, they are unable to consume large amounts of bulky forage to provide energy and nutrients for potential productivity. One of the ways to solve this problem is to increase the feeding level of first-calf heifers at the expense of concentrates. The assessment of the relationship between the level of feeding and the level of productivity and health of the animal was carried out by studying metabolic processes using biochemical markers of blood serum. The studies were carried out in the Moscow region for 150 days on 36 first-calf heifers, which were divided into three groups of 12 cows each according to the group-analogue principle. The control group received a ration balanced according to detailed norms for annual productivity of 8 to 9 thousand kilograms of milk per lactation. The second experimental group received a ration with increased content of metabolizable energy by 7.8% and crude protein by 8.2% of the requirement, the third group – by 15.1% and 16.4%, respectively, due to additional feeding of a targeted protein- vitamin-mineral concentrate. The researchers found that increasing the feeding level allowed to increase the live weight of first-calf heifers by 5.6% and 6.8% and the average daily milk yield by 6.4% and 9.6% in comparison with the control, and did not have a negative effect on the character of metabolism. All indicators of protein, lipid, carbohydrate and mineral metabolism were within reference values. The content of the albumin fraction in the blood serum of cows in the experimental groups was 39.7% and 39.5% of the content of total protein, while in the control group it was 36%. A significant increase in the content of the albumin fraction, by 5.12% (p=0.04) in the 2nd experimental group and by 7.24% (p=0.01) in the 3rd experimental group, with a simultaneous decrease in the content of total protein, characterizes a higher intensity of biosynthetic processes in the body associated with increased milk formation. Indicators of mineral metabolism were also within the physiological norm. The increase in magnesium content in cows of the 3rd experimental group is associated with an increase in its level in the diet of first-calf heifers. The increase in alkaline phosphatase activity indicates an increase in the functional activity of the liver, which is also associated with milk formation.

Reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding

Inbreeding is one of the main criteria in programs for the conservation and use of genetic resources, and it can be used to control genetic processes in populations of farm animals. The use of inbreeding involves the production and consolidation of rare genotypes, which determine the outstanding quality of animals. The purpose of the work was to determine the reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding. The research was carried out in the pedigree farm in the Kaluga region. The research of the reproductive ability of first-calf heifers obtained through inbreeding and outbreeding were shown significant differences in the duration of the calving interval. So, cows obtained through the remote inbreeding had the lowest duration calving interval (385.4 days) and their herdmates from outbreding had the longest calving interval (404,5 days), the difference was 19.1 days (p<0.05) or 5.0%. Cows from remote inbreeding had the shorter calving interval than their herdmates from moderate inbreeding by 15.9 days (p<0.05) or 4.1%. It was found that higher milk yields for 305 days of the first lactation had cows obtained through remote inbreeding (6413.1 kg), and low milk yields of milk were obtained from first-calf heifers from moderate inbreeding (5634.8 kg), the difference was 778.3 kg (p<0.05) or 9.0%. They also surpassed the milk yield of their herdmates obtained from outbreeding by 266.6 kg (p<0.05) or 4.3%. First-calf heifers obtained through moderate inbreeding were inferior in milk yield to herdmates from outbreeding by 511.7 kg or 9.1% (p<0.05).

Use of the feed additive Optimus in feeding of cows of Black-and-White breed

An important limiting factor in intensive milk and beef production systems is protein. The lack of protein feed provokes the need to use modern and new protein sources. Modern approaches to the system of standardized feeding of ruminant animals help to improve the quality of protein in rations, which is assessed by the ratio of its degradable and non-degradable parts. In this regard, innovative feed additives such as Optimus to stimulate microbial protein synthesis and a source of non-degradable protein are of particular interest. The purpose of the research was to study the effect of Optimus feed additive on the productive traits of highly productive Holstein cows under the conditions of industrial milk production technology. In order to conduct the study, 3 groups (control and two experimental) of Holstei highly productive first-calf heifers were formed on the principle of pair-analogs taking into account age, live weight, lactation period, and productivity. In the ration of the cows of the 1st experimental group 500 g/head/day of Optimus additive was added instead of 500 g of KK-60-1 compound feed, in the 2nd experimental group 1 kg/head/day was added instead of 1 kg of KK-60-1 compound feed. Thus, the diff erence in milk yield between cows of the 1st and 2nd experimental groups compared to the control group was 87,3 and 148,0 kg, respectively. Milk production coefficients in the 1st and 2nd experimental groups were also higher than the control group by 15,0 (p < 0,05) and 30 kg (p < 0,01). Thus, the use of the feed additive Optimus in doses of 500 g/head/day and 1 kg/head/day instead of compound feed KK-60–1 in feeding of Holsteinized first-calf heifers during the period of increasing the milk yield under the conditions of industrial milk production technology showed positive results. A more optimal dosage should be 1 kg/head/day.

INFLUENCE OF TIMING OF ARTIFICIAL INSEMINATION OF FIRST-CALF HEIFERS ON THE INDICATORS OF THEIR MILK PERFORMANCE AND THE CHARACTER OF THE LACTATION CURVE

The article presents the results of a study on the dependence of the milk performance in first-calf heifers on the timing of their productive insemination, carried out using modern automated systems for monitoring the physiological state of animals. It has been established that first-calf heifers inseminated on days 90–110 of lactation possess the highest milk yield, which is 9.29–21.96% higher than that of cows inseminated at earlier or later dates.

ХИМИЧЕСКИЙ СОСТАВ И ТЕХНОЛОГИЧЕСКИЕ СВОЙСТВА МОЛОКА КОРОВ-ПЕРВОТЕЛОК ПРИ РАЗНЫХ СПОСОБАХ СОДЕРЖАНИЯ И ТЕХНОЛОГИЯХ ДОЕНИЯ

Industrial milk production is based on high-tech processes at the current stage. Strong requirements imposed on milk quality are due to the quality of raw materials for producing a wide range of dairy products. The production of milk that meets sanitary and hygienic standards and the requirements of regulatory and technical documents (regulations and standards) is a priority in dairy cattle breeding. Analysis of the chemical composition of milk obtained from the control and experimental groups showed that the milk fat content was the highest (4.06 %) in the 1st experimental group and exceeded the control (3.93 %) and the 2nd experimental (3.94 %) groups. Under the loose housing system the mass fraction of protein was 3.15 %; the value was 0.02 points larger compared with the tie housing system. The milk density in the animal groups ranged from 1027.0 to 1029.0 kg/m3 , which meets the requirements of GOST 31449-2013. The largest mass fraction of dry solids in milk was found in the 2nd experimental group (12.58 %). The data analysis indicates that the housing system type and the milking technology of first-calf heifers have an effect on the number of milk fat globules per 1 cm3 and their diameter. The analysis of the quantitative and qualitative composition of fat globules has provided more complete data about the milk fat fraction, which is a crucial index in milk production. The milk obtained from the Holstein breed heifers in the studied groups can be used for cheese making. The third yogurt sample had a milky white colour, homogeneous throughout the mass; the consistency was homogeneous, with good curd tension and low viscosity; the sample had a pure, fermented milk flavour, without foreign traces.

КОЛОСТРАЛЬНЫЙ ИММУНИТЕТ ТЕЛЯТ НА ФОНЕ ИММУНОКОРРЕКЦИИ ОРГАНИЗМА КОРОВ-МАТЕРЕЙ

The aim of this work was to evaluate the effect of immunostimulating drugs Salus-P-E and Bovistim-K on the quality of colostrum and the immune status of calves after drinking colostrum. Work was carried out on first-calf heifers of the Holstein breed. Three groups of deep-calving cows were selected according to the principle of analogue groups of 10 animals each. Cows of the 1st experimental group were injected intramuscularly in the middle third of the neck with Salus-P-E at a dose of 10 ml three times 60, 30 and 15 days before the expected date of calving, the 2nd experimental group – Bovistim-K at the same time and dose, in the control group, biological preparations were not used. Colostrum sampling was carried out twice: within 60 minutes after calving and 24 hours after calving. In the second series of experiments, we studied the clinical and physiological state and blood parameters of newborn calves after drinking colostrum. The colostrum of cows of the 1st and 2nd experimental groups contained more immunoglobulins than control samples by 23,8 and 27,67 g/l; total protein - by 3,08 and 3,32%; the level of caseins – by 0,34 and 0,22%, respectively. Against the background of immunocorrection of the organism of deep-calving mother cows, there is an increase in the amount of hemoglobin, total protein, reserve alkalinity and certain changes in the ratio of protein fractions of blood of newborn calves. In the first day of life, an increase in the blood serum of calves of the experimental groups was found compared to the control: albumin by 7,9 and 8,4%; α-globulins – by 18,6 and 15,7%, β-globulins – by 22,1 and 16,9%, γ-globulins by 24,4 and 21,4%, respectively. Drinking high-quality colostrum (Brix over 24) contributed to an increase in average daily gains in calves of the 1st and 2nd experimental groups by 18,2 and 20,2%. The use of immunostimulating drugs Salus-P-E and Bovistim-K increases the immunocompetent properties of colostrum, which contributes to the formation of a high level of colostral immunity in the body of newborn calves, reducing morbidity and improving growth and survival rates.