Higher Milk Yield Research Articles

Influence of breed and environment on leukocyte telomere length in cattle.

High milk yield is associated with reduced longevity in high-producing dairy cattle breeds. Pre-term culling leads to high replacement heifer demand and economic losses for the dairy industry. Selection for this trait is limited because of low heritability and difficulties in phenotype measurement. Telomeres are elements found at the ends of chromosomes, consisting of repetitive DNA sequences, several thousand base pairs in length, coupled with nucleoprotein complexes. Eventually, in humans and most other animals, telomere length reduces with age. When telomeric DNA is truncated to a critical length, cell ageing, cell cycle arrest, and apoptosis are induced. As a result, telomere length can be considered as a predictor of health risks and an individual's lifespan. The leukocyte telomere length may be used as a proxy phenotype of productive lifespan to improve cattle selection. Our objectives were to assess the effects of breed and breed group (dairy vs. beef) on the leukocyte telomere length and to estimate the effect of cold climate on this trait in Kalmyk cattle populations from the South (Rostov Oblast) and Far North (Republic of Sakha) regions of Russia. The leukocyte telomere lengths were estimated computationally from whole-genome resequencing data. We leveraged data on leukocyte telomere length, sex, and age of 239 animals from 17 cattle breeds. The breed factor had a significant effect on leukocyte telomere length across our sample. There was no difference in leukocyte telomere length between dairy and beef groups. The population factor had a significant effect on leukocyte telomere length in Kalmyk animals. In conclusion, we found that breed, but not breed group (dairy vs. beef), was significantly associated with leukocyte telomere length in cattle. Residence in colder climates was associated with longer leukocyte telomere length in Kalmyk breed cattle.

Factors Influencing Milk Yield During Lactation of D’man Ewes in its Cradle in Algeria

Abstract A study was conducted at the National Institute of Agricultural Research (Adrar station) between 2017 and 2019 to assess the milk yield potential of prolific D’man ewes. A total of 210 daily milk production records from (of) 21 D’man ewes were collected during three successive lambings with the weighing method before and after feeding followed by manual milking. In addition, the effects of birth type, lambing rank, birth season and weight of ewes to the struggle (at breeding) on milk production were analyzed. The least-squares averages of daily and total milk production of D’man ewes were 0.85 ± 0.03 kg and 59.1 ± 0.96 kg, respectively, and the highest daily milk yield was observed in the second week of lactation. Ewes suckling more than two lambs had the highest milk yield. Indeed, ewes with triplets or more (+57.3%) and twins (+22.1%) have a significantly higher milk yield (P<0.01) than ewes nursing single lambs. The effect of the other factors was not significant on milk production of D’man ewes. It can be concluded that increasing the quantity of milk produced per ewe according to the number of lambs suckled will help to make the most of multiple lambings thanks to a low mortality rate and improved growth, especially during the first month of lactation.

Pathogen-specific patterns of milking traits in automatic milking systems

Early detection of intramammary infection (IMI) can improve animal health and welfare in dairy herds. The implementation of sensors and automatic milking systems (AMS) in dairy production inherently increases the amount of available data and hence also the potential for new approaches to mastitis management. To utilize the full potential of data from AMS and auxiliary sensors, a better understanding of physiological and pathological changes in milking traits associated with different udder pathogens may be imperative. This observational study aimed to investigate pathogen-specific patterns in milking traits recorded in AMS. The milking traits included; online somatic cell count (OCC), electrical conductivity (EC), milk yield (MY), and average milk flow rate (AMF). Data were collected for a study period of 2 years and included 101 492 milkings from 237 lactations in 169 cows from one farm. Measurements of OCC were recorded at cow-level and data on EC, MY, and AMF were obtained at quarter-level. In addition to the data obtained from the AMS, altogether 5756 quarter milk samples (QMS) were collected. Milk samples were obtained monthly for bacteriological culturing. We included findings of 13 known mastitis pathogens to study pathogen-specific patterns in milking traits. These patterns were compared with those in a baseline group consisting of cows that did not have any positive milk culture results throughout the lactation period. Patterns of the milking traits are described for all positive samples both across 305 d in milk (DIM), and in the 15-d period before a positive bacteriological sample. The association between a positive sample and the milking traits (ln(OCC), EC-IQR; the ratio between the quarter with the highest and the quarter with the lowest level of EC, and MY) for the 15 d before the detection of a pathogen was assessed using mixed effects linear regression models. All pathogens were associated with alterations in the level and variability of ln(OCC) relative to lactations with no positive bacteriological samples. A positive sample for Staph. aureus was associated with increased values for MY during the 15 d before a positive diagnosis. It is biologically plausible to interpret changes in OCC and EC-IQR as consequences of an intramammary infection (IMI), while higher MY in bacteriologically-positive cows is most likely linked to the increased risk of infection in high-yielding cows. In this study, the most notable changes in the traits (OCC and EC-IQR) were observed for Staph. aureus and Strep. dysgalactiae, followed by Strep. simulans, Strep. uberis, and Lactococcus lactis. Even if we did not detect significant associations between positive bacteriology and EC-IQR, visual assessment and descriptive statistics indicated that there might be differences suggesting that it could be an informative trait for detecting infection when combined with OCC and possibly other relevant traits using machine learning algorithms.

Milking Temperament and Its Association with Test-Day Milk Yield in Bulgarian Murrah Buffaloes.

The goal of this research was to evaluate milking temperament and its relationship with test-day milk (TDMY0) yield in Bulgarian Murrah buffaloes. This study involved 90 buffalo cows reared under a tie-stall production system which were milked twice a day with a milking pipeline. The behavioral responses of the buffaloes were reported during preparation for milking and during actual milking. The average temperament score during preparation for milking was 1.83, and 1.93 during milking itself. The most common reaction was leg lifting (18.9%), followed by cows moving on the stall bed (10%), definite kicking (9.9%), and 13.3% managing to remove the milking cluster during milking. The frequency of buffaloes showing adverse reactions (scores 4 and 5) increased considerably during milking compared to preparation for milking. Repeated scoring of temperament during the same lactation did not show a significant difference in the frequency of temperament assessments both in preparation for milking and during milking. The minimal difference may be due to the accuracy of the assessment or a momentary change in the condition of the animals during the two scorings. Cows with the most unwanted milking behavior (scores 5 and 4) had the highest LS means for TDMY, 8.18 kg and 7.65 kg, respectively. The reasons for these buffaloes remaining until later lactations was their high milk yield and the injection of oxytocin before milking, which helps them to be fully milked.

Impact of pre-partum nutraceutical or monensin intraruminal boluses on colostrum quality and Holstein dairy cows’ performance: exploratory field study

A smooth transition phase is the key for optimal dairy cows’ performance and reduced antibiotics use. Therefore, the objective of our Our study was to compare the effect of an antibiotic growth promoter and a nutraceutical bolus, onhealth, colostrum, milk production, and profitability in transition dairy cows. Seventy-five animals blocked by parity, previous milk yield, lactation length, and body condition score (BCS) were assigned in a randomised design to 1 of 3 groups: control (CON; N = 26) receiving no treatment; monensin (MON; N = 27) receiving, a slow-releasing intraruminal bolus of sodic monensin at −20 d relative to expected calving; nutraceutical (ECS; N = 22) receiving, at −5 d before the expected calving an intraruminal bolus of Echinacea purpurea dry extract, vitamin E, l-carnitine and Silybum marianum released within 24h. Colostrum yield and density were recorded; its composition and immunoglobulins content were analysed. Every 20 days BCS was recorded; individual milk yield was recorded daily until 70DIM and monthly thereafter until 305 DIM. Milk quality was tested monthly. An economic evaluation until 70DIM was performed. Colostrum and Δ BCS were analysed by analysis of covariance. Economics and BCS were analysed with ANOVA, and milk yield and quality with ANOVA for repeated measures. The MON and ECS had lower colostrum protein and His, Arg, Ala, Met, Val and Ile content, and in higher milk yield until 35 (ECS) and 70 (MON) DIM compared to the CON. A trend for a higher partial income was observed for MON and ECS compared to the CON group, suggesting a positive impact of the treatments.

EFFECT OF GLOBAL WARMING ON SUSTAINABLE LIVESTOCK PRODUCTION IN THE SUB-SAHARAN AFRICA

The greenhouse gas emissions from Animal production related activities has turn out to be an important cause of global warming. This can be attributed to the continent-wide massive burdens arising from the switch in food consumption pattern. Anthropogenic activitiesrelated to livestock production contribute 37% of methane (CH4) emission, 9% of carbon dioxide (CO2) output and utilize 8% of the world water. An estimated aggregate of 7.1 billion tonnes of CO2 are generated by the feed and livestock industries. The effect of global warming is presently being experienced such as unstable rainfall pattern, drought, extended walk in search of pasture and water, coupled with significant impact on livestock productivity (rate of weight gainand milk production potentials).The potential of Sub-Saharan Africa to achieve sustainable animal production is being threatened by global warming, it is. therefore necessary to leverage on the use of livestock breed that combine the heat tolerance of the local stock with the high milk yield of the exotic breed (crossbreeding) to produce an improved breed of livestock. Ameliorative strategies such as strategic supplementation of diets, matching genetics to specific systems and management of manure with potential to improve productivity of livestock should be included into livestock production systems in the Sub-Sahara Africa. The use of Geographic Information System (GIS) techniques will also assist to acquire ideal results on susceptibility of smallholder farmers. Finally, there is the need for shift in policy to promote the livelihood of indigenous livestock farmers under favourable environmental conditions.

Signatures of positive selection after the introduction of genomic selection in the Finnish Ayrshire population

The Finnish Ayrshire (FAY) belongs to the Nordic Red breeds and is characterized by high milk yield, high milk components, good fertility, and functional conformation. The FAY breeding program is based on genomic selection. Despite the benefits of selection on breeding values, autozygosity in the genome may increase due to selection, and increased autozygosity may cause inbreeding depression in selected traits. However, there is lack of studies concerning selection signatures in the FAY after genomic selection introduction. The aim of this study was to identify signatures of selection in FAY after the introduction of genomic selection. Genomic data included 45,834 SNPs. The genotyped animals were divided into 2 groups: animals born before genomic selection introduction (6,108 cows) and animals born after genomic selection introduction (47,361 cows). We identified the selection signatures using 3 complementary methods: 2 based on identification of selection signatures from runs of homozygosity (ROH) islands and one based on the decay of site-specific extended haplotype between populations at SNP sites (Rsb). In total, we identified 34 ROH islands on chromosomes 1, 3, 6, 8, 12-15, 17, 19, 22, and 26 in FAY animals born before genomic selection (between 1980 and 2011) and 30 ROH islands on chromosomes 1-3, 13-17, 22, and 25-26 in FAY animals born after genomic selection introduction (between 2015 and 2020). We additionally detected 22 ΔROH islands on chromosomes 2-3, 11, 13, 14, 16, 18, 20, and 25-26. Finally, a total of 31 Rsb regions on chromosomes 2, 3, 14, 18, 20, and 25 were identified. Based on the results, genomic selection has favored certain alleles and haplotypes on genomic regions related to traits relevant in the FAY breeding program: milk production, fertility, growth, beef production traits, and feed efficiency. Several genes related to these traits, e.g., PLA2G4A, MECR, CHUK, COX15, RICTOR, SHISA9, and SEMA4G overlapped or partially overlapped the observed selection signature regions. The association of genotypes within these regions and their effects on traits relevant in the FAY breeding program should be studied and genetic regions undergoing selection monitored in the FAY population.

A Single-Cell Transcriptome of Bovine Milk Somatic Cells.

The production of milk by dairy cows far exceeds the nutritional needs of the calf and is vital for the economical use of dairy cattle. High milk yield is a unique production trait that can be effectively enhanced through traditional selection methods. The process of lactation in cows serves as an excellent model for studying the biological aspects of lactation with the aim of exploring the mechanistic base of this complex trait at the cellular level. In this study, we analyzed the milk transcriptome at the single-cell level by conducting scRNA-seq analysis on milk samples from two Holstein Friesian cows at mid-lactation (75 and 93 days) using the 10× Chromium platform. Cells were pelleted and fat was removed from milk by centrifugation. The cell suspension from each cow was loaded on separate channels, resulting in the recovery of 9313 and 14,544 cells. Library samples were loaded onto two lanes of the NovaSeq 6000 (Illumina) instrument. After filtering at the cell and gene levels, a total of 7988 and 13,973 cells remained, respectively. We were able to reconstruct different cell types (milk-producing cells, progenitor cells, macrophages, monocytes, dendritic cells, T cells, B cells, mast cells, and neutrophils) in bovine milk. Our findings provide a valuable resource for identifying regulatory elements associated with various functions of the mammary gland such as lactation, tissue renewal, native immunity, protein and fat synthesis, and hormonal response.

Prevention of ketosis in cows: the role and effectiveness of Кеххtone

Ketosis is a common metabolic disease in dairy cattle that is often diagnosed in the late stages of pregnancy or early stages of lactation, especially in high-yield cows. To counteract this disease, we used the drug Kexxtone, which protects for 95 days, starting from 3–4 weeks before the planned calving. The study showed that the administration of this drug led to a significant decrease in the level of ketone bodies in the blood of cows on the third and ninth day after calving. Notably, on the third day after calving, the content of ketone bodies in the blood of animals treated with the drug during the second lactation was significantly lower than in the control group of cows by 1.38 times (Р < 0.05), on the ninth day of research, this indicator in cows of this group significantly decreased by 2.48 times and amounted to 0.81 ± 0.05 mmol/L (Р < 0.01), and in the control group – 2.01 ± 0.31 mmol/L. It was also found that the insemination index was almost the same in cows during the second lactation. Still, a significant decrease in this indicator was noted in the third and fourth lactation of cows when using the drug Kexxtone. Thus, during the third lactation in experimental cows, this index was 1.6 ± 0.18 (Р < 0.01), and in the control group – 2.13 ± 0.35. In cows of the experimental groups, a higher average daily milk yield was observed compared to animals that were not given the drug. In some cows during the fourth lactation, which was not treated with Kexxtone, high levels of ketone bodies were detected in the blood, which may indicate the need for health monitoring and additional measures to prevent ketosis. In addition, a high average daily milk yield was found in cows from the experimental groups, possibly due to the drug Kexxtone's positive effect on the animal body's physiological processes and increased productivity of dairy cattle. These results indicate the potential benefits of using Kexxtone to ensure the health and productivity of cows at different stages of their life. These results allow us to recommend the use of the drug to prevent the occurrence of ketosis and increase cow yield. Additional research may be helpful for a deeper understanding of the mechanisms of the drug's action and its effect on the body and productivity of cows.

Archetypal clustering reveals physiological mechanisms linking milk yield and fertility in dairy cattle

Fertility in dairy cattle has declined as an unintended consequence of single trait selection for high milk yield. The unfavorable genetic correlation between milk yield and fertility is now well-documented, however, the underlying physiological mechanisms are still uncertain. To understand the relationship between these traits, we developed a method that clusters variants with similar patterns of effects and, after the integration of gene expression data, identifies the genes through which they are likely to act. Biological processes that are enriched in the genes of each cluster were then identified. We identified several clusters with unique patterns of effects. One of the clusters included variants associated with increased milk yield and decreased fertility, where the 'archetypal' variant (i.e., the one with the largest effect) was associated with the gene GC, while others were associated with TRIM32, LRRK2, and U6. These genes have been linked to transcription and alternative splicing, suggesting that these processes are likely contributors to the unfavorable relationship between the 2 traits. Another cluster, with archetypal variant near DGAT1 and including variants associated with CDH2, BTRC, SFRP2, ZFHX3, and SLITRK5, appeared to affect milk yield but have little effect on fertility. These genes have been linked to insulin, adipose tissue, and energy metabolism. A third cluster with archetypal variant near ZNF613 and including variants associated with ROBO1, EFNA5, PALLD, GPC6, and PTPRT were associated with fertility but not milk yield. These genes have been linked to GnRH neuronal migration, embryonic development, and/or ovarian function. The use of archetypal clustering to group variants with similar patterns of effects may assist in identifying the biological processes underlying correlated traits. The method is hypothesis-generating and requires experimental confirmation. However, we have uncovered several novel mechanisms potentially affecting milk production and fertility such as GnRH neuronal migration. We anticipate our method to be a starting point for experimental research into novel pathways which have been previously unexplored within the context of dairy production.

Milk recording data indicates the importance of fertility, including age at first calving, on the progression of first lactation cows to second lactation.

Dairy farmers do not recoup the rearing costs incurred from birth to first calving until second lactation but varying proportions of first lactation cows are removed from the herd before second calving. Herein, we used milk recording data to examine the outcomes and performance of first lactation cows to gain insight into farmer decisions to keep or remove them from the herd. An InterHerd+ dataset derived from 500 milk recording dairy herds in UK was used to examine first lactation cows which calved in 2020. Of 29,128 first lactation cows that calved in 2020, 82.6% remained within the herd and re-calved, 4.9% conceived but exited the herd before re-calving, 6.0% were served but exited the herd after failing to conceive and 6.6% exited the herd without being served. The fertility data on these cows support the logical conclusion that farmers retain cows that are served and conceive sooner, possibly in order to keep within a broadly seasonal calving pattern. Cows which were served but not conceived had a median AFC 16-20 days greater than the median AFC for those that conceived. Farmers may also be retaining cows with relatively high milk yields and lower somatic cell counts, or these parameters may be an indicator of a range of attributes affecting the farmer's decision. The data also suggest that farmers are rearing more replacements than required, because over one third of the cows removed in first lactation are never served, and 70% of these are sold within 120 days post-partum. These cows had a significantly older median age at first calving of 818 days, but their early removal without serving suggests there is an oversupply of replacements forcing farmers to dispose of these cows early in lactation. In order to develop a deeper understanding of herd turnover and replacement, future work could examine cow removals in lactation 2 onwards.

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.

Randomized clinical trial evaluating the effects of administering acidogenic boluses at dry-off on udder health, milk yield, and herd removal

Acidogenic boluses can mitigate potential negative effects of high milk yield at dry-off on udder health. This randomized controlled trial aimed to investigate the effect of administering acidogenic boluses at dry-off on dry period intramammary infection (IMI) dynamics and on milk production parameters, somatic cell count linear score (LSCC), clinical mastitis (CM), and herd removal in the next lactation. A total of 901 cows from 3 dairy farms were randomly allocated to a control (CON, n = 458; no administration of acidogenic boluses at dry-off) or treatment group (TRT, n = 443; administration of 2 acidogenic boluses at dry-off). Quarter milk samples were collected at dry-off and after calving and submitted for bacteriological milk culture. The effects of treatment on the presence of quarter-level postpartum IMI, cure of existing IMI, and acquisition of new IMI, and on the prevalence of cow-level high LSCC (LSCC ≥4) in the first 30 days in milk (DIM) were analyzed using mixed effects logistic regression. Mixed linear regression was used to analyze cow-level milk production parameters (i.e., milk yield, fat corrected milk, fat and protein yield, and LSCC) in the first 90 DIM and until 300 DIM. For CM and herd removal, Cox proportional hazard regression models were used. In addition to treatment group, lactation group at dry-off, presence of high LSCC in the last test-day, average milk yield in the week before dry-off, presence of CM in the lactation of enrollment, and biologically relevant interactions were offered in all models. There was no evidence of a difference in IMI dynamics or in milk, fat corrected milk, protein or fat yields in the subsequent lactation between groups. The TRT group had a lower LSCC in the first 2 mo postpartum compared with the CON group (2.58 ± 0.3 vs. 2.92 ± 0.3 and 2.42 ± 0.3 vs. 2.81 ± 0.3, for first and second month postpartum). The prevalence of high LSCC in the first 30 DIM was 9.1% lower in the TRT compared with the CON group (16.3% vs. 25.5%; risk difference: -9.2; 95% confidence interval [CI]: -15.8, -2.5). Cows in the TRT group exhibited reduced hazards of CM in the subsequent lactation compared with cows in the CON group (hazard ratio: 0.75; 95% CI: 0.63, 0.89) as well as a reduced hazard of herd removal (hazard ratio: 0.82, 95% CI: 0.77, 0.88). The administration of acidogenic boluses as a component of dry-off management is a promising approach to maintain good udder health and reduce the hazard of CM and herd removal during the subsequent lactation.

Developmental programming of production and reproduction in dairy cows: III. Association of level of maternal milk production with offspring's birth weight, survival, productive and reproductive performance and AMH concentration from birth to the first lactation period

Although some studies investigated the relationship of dam milk production (DMP) with offspring birth weight and productive performance, limited information is available on the association of level of DMP with reproductive performance in dairy cows. Therefore, the present study was conducted to understand whether dams with various levels of milk production produce offspring with different fertility. In study I, offspring were classified based on the level of DMP into five categories, including DMP1 (dams with <10.00 × 103 kg of 305-day milk production), DMP2 (dams with ≥10.00 × 103 kg and <12.00 × 103 kg of 305-day milk production), DMP3 (dams with ≥12.00 × 103 kg and <14.00 × 103 kg of 305-day milk production), DMP4 (dams with ≥14.00 × 103 kg and <16.00 × 103 kg of 305-day milk production) and DMP5 (dams with ≥16.00 × 103 kg of 305-day milk production). In study I, data of birth weight, milk yield and reproductive variables of 14,536 offspring born to lactating dams and corresponding data of DMP were retrieved. In study II, blood samples (n = 339) were collected from offspring in various categories of DMP for measurement of serum AMH. Offspring were heavier at birth in DMP4 and DMP5 categories than DMP1 and DMP2 categories (P < 0.05). Milk yield of offspring increased as DMP elevated (P < 0.05); however, offspring in DMP1 and DMP2 categories produced higher milk as compared with their dams during primiparity (P < 0.05) whereas offspring in DMP3, DMP4 and DMP5 categories produced less milk as compared with their dams during primiparity (P < 0.05). Milk fat to protein ratio during the first month of lactation was greater in DMP4 and DMP5 categories than DMP1 category (P < 0.05). Offspring of DMP4 and DMP5 categories were inseminated and conceived at younger ages than offspring of DMP1 category during nulliparity (P < 0.05). Calving to conception interval was longer in DMP5 than DMP1 category in primiparous offspring (P < 0.05), but concentration of AMH did not differ among various categories of DMP (P > 0.05). In conclusion, dams with greater level of milk production produced heavier offspring with higher milk yield but worse transgenerational improvement in milk production and diminished reproductive performance, which were seemingly under higher pressure of negative energy balance during the first month of lactation.

Productivity and milk quality of Saanen and Anglo- Nubian breeds of goats under the conditions of the Lower Volga region

Prospects for the development of dairy goat farming and goat milk production in many countries of the world, including Russia, are directly related to the dietary and healing properties of the product. An urgent problem is the comparative assessment of the adaptive and productive traits of dairy goats of imported selection under various ecological and climatic conditions of Russia, including the conditions of the sharp continental climate of the Lower Volga region. The purpose of the work was to give a comparative assessment of the eff ectiveness of breeding lactating goats of Saanen and AngloNubian breeds of imported selection under the conditions of the sharp continental climate of the Lower Volga region. The object of research was imported dairy goats. Two groups of female goats of Saanen and Anglo-Nubian breeds of the fi rst lactation of 10 heads in each were formed, taking into account their live weight, age of insemination and origin. The duration of the scientific and farm experiment was 210 days.Consistently high milk yield was found in goats of Saanen breed compared with the milk yield of their herdmates of Anglo-Nubian breed. The signifi cant diff erence in milk yield in favor of Saanen goats by months ranged from 13,24 to 16,51 % (p &lt; 0,05). In general, during lactation the superiority of Saanen goats over their Anglo-Nubian herdmates in terms of milk yield was 61,2 kg or 15,75 %. A comparative analysis of quality indicators revealed a significant superiority of milk from goats of Anglo-Nubian breed such as in the mass fraction of fat by 1,48 abs.% (p &lt; 0,05), in the mass fraction of protein by 0,24 abs.% (p &lt; 0,05), in terms of milk fat yield by 3,15 kg (p &lt; 0,05). It was found as a result that in the production of milk from goats of Anglo-Nubian breed, the level of profitability of milk with basic fat content (3,5 %) was higher by 27,78 abs.% compared with herdmates of Saanen breed.

Milk productivity and reproductive capacity in Holstein cows of Moscow region

The article presents the reproductive quality indicators of the Holstein herd of APA (C) “Kuzminsky” (Moscow region) with different milk productivity levels. Some patterns have been identified for the herd, reflecting associations between reproductive and productive traits. The coefficient of the reproductive capacity ranges in the herd from 0.976 to 0.986, and the highest average rate was noted among cows with the highest milk yields in the herd. It’s noteworthy that the largest group (n=100) with an average level of milk yield per herd was characterized by the lowest coefficient. The average calving interval is 372 days, which can be explained by an extended service period; the dry period duration in cows with high milk yields is the maximum among the studied livestock.

MANAGEMENT OF REPRODUCTION AND ASSESSMENT OF THE INFLUENCE OF TIMING OF ARTIFICIAL INSEMINATION ON MILK PERFORMANCE INDICATORS AND THE CHARACTER OF LACTATION CURVE FOR COWS OF SECOND LACTATION

The article presents the results of the study on reproduction management and assessment of milk performance in cows of the second lactation. It has been established that, cows inseminated on days 90-110 after calving, have the highest milk yield, which is 16.04 - 28.76% higher than that of cows inseminated at earlier or later dates. The study was conducted using automated systems for identifying and monitoring the physiological state of animals, ensuring accurate detection of heat and effective insemination of cows in a flow-shop milk production system.

Productivity of cows of the red steppe breed, considering the physique

As a result of a comparative assessment of the qualitative indicators of milk productivity of dairy cows of the red steppe breed of the III lactation, two controlled groups of animals were selected for the study according to two body types. It was found that broad-bodied cows have higher milk yields by 5.91% compared to narrow-bodied animals. Broad-bodied cows also produce more milk fat and protein during the standard lactation period, by an average of 21.36% and 20.5%.

THE INFLUENCE OF FEMALE ANCESTORS ON MILK PERFORMANCE IN FIRST- CALF COWS OF THE HOLSTEIN BREED DAIRY CATTLE OF DOMESTIC SELECTION

The results of studies on the influence of female ancestors on the milk performance in first-calf cows of the Holstein breed of dairy cattle of domestic selection are presented. The highest values of milk yield, the amount of milk fat and protein, as well as the mass fraction of protein in milk were observed in daughters whose mothers’ milk yield was over 10,000 kg and amounted to 9295 (p≤0.01), 341.3, 313.3 (p≤0.01) kg, 3.37% (p≤0.05), respectively. First-calf cows with a milk yield of MM 9001-9500–9227 kg (p≤0.001) have a high degree of abundant milk production. They also had the highest amount of milk fat and protein, which amounted to 344.8 (p≤0.01) and 309.4 (p≤0.001) kg, respectively. The highest milk yield, milk fat and protein content were in first-calf cows with a milk yield of MF over 14.000 kg. The realization of the genetic potential for milk yield over 305 days of lactation was 102.1%.

Effects of parity, calving season, and previous lactation's milk yield on fertility of dairy cows on a commercial farm.

This study investigated the effects of parity, season, and the previous lactation's milk yield on fertility in dairy cows. A total of 5,514 calving records for Holstein cows that calved between 2016 and 2018 on a single large dairy farm in Japan were used for analysis. The proportion of cows that get pregnant by 360 days after calving was defined as the percentage of all cows eligible for breeding that became pregnant. In the all-cow model, pregnancy probability associated with both parity and calving season (p < 0.05). Pregnancy probability decreased with an increase in parity, with hazard ratios (HRs) of 1.75 (1.58-1.94) for parity 1, 1.25 (1.13-1.39) for parity 2, 1.15 (1.04-1.29) for parity 3, and 1.13 (1.00-1.27) for parity 4, relative to parity ≥5. In terms of calving season, the lowest pregnancy probability was found in spring, and the HRs relative to spring were 1.16 (1.07-1.26) for summer, 1.35 (1.24-1.47) for autumn, and 1.17 (1.07-1.27) for winter. In the multiparous-cow model, pregnancy probability associated with the previous lactation's milk yield (p < 0.05), but not with parity or calving season. Cows with high and middle previous milk yields had lower pregnancy probabilities than those with low milk yields.