High-producing Cows Research Articles

Risk factors of clinical endometritis in an Iranian dairy farm

Clinical endometritis is one of the most common causes of declining reproductive performance in dairy cows. The purpose of this study was to investigate the effects of some factors including cow’s parity, milk yield, dystocia, retained placenta, calf sex, calving season, abortion, and stillbirth on the incidence of clinical endometritis and the effect of clinical endometritis on open days in an Iranian dairy farm. Uterine health of 557 dairy cows was evaluated by rectal palpation and ultrasonography during 30-35 days after calving. The presence of mucopurulent secretions in the vagina and vulva as well as the ultrasonographic observation of echogenic secretions in the uterine lumen were considered endometritis. The effect of the mentioned factors on the incidence of clinical endometritis was then analyzed in univariate and multivariate logistic regression models. The chance of developing clinical endometritis in the low-producing cows was 27.2% higher than that of the high-producing cows (p=0.06). Other parameters had no significant effect on the incidence of endometritis. The incidence of clinical endometritis in the studied herd was 49.5%. Based on the results of this study, the low milk yield may be a risk factor for developing clinical endometritis in the studied herd's condition, while parameters of the parity, dystocia, retained placenta, calf sex, calving season, abortion, and stillbirth was not effective in the occurrence rate of endometritis. There was no association between clinical endometritis and days open in the studied herd.

5 Rumen microbiome and metabolome in dairy cattle performance

Abstract Cattle rumen microbiome converts fibrous feed to nutrients that directly influence cattle’s growth and performance. Recent research has revealed the composition and function of rumen microbiome can affect many economically important traits in cattle such as feed efficiency, milk/meat yield and quality, methane emission, metabolic health and so on. In this presentation, the research on the assessment of to what extent the rumen microbiome and its metabolites, as well as host metabolites contribute to milk production and quality traits will be focused and discussed. It has been evident that some dairy cows can produce large amounts of milk under the same nutritional and management conditions. Recent research has revealed that in addition to host genetics and diet, parity and days in milk of dairy cows can affect the rumen microbiota, and both core and pan rumen bacteriome can potentially contribute to variations of milk production traits. Additionally, the analysis of rumen metagenomics and metabolomics of dairy cows with varied milk production yield showed that some key bacterial taxa (for example, Prevotella species), and their functions (such as branched-chain amino acids biosynthesis, methanogenesis), some rumen microbial metabolites (mainly amino acids, carboxylic acids, and fatty acids) significantly differed between high and low production cows. Further integrated analysis with serum metabolomics of the cos revealed the varied contributions of rumen microbial composition, functions, metabolites, and the serum metabolites to the milk protein yield of a dairy cow, a potential new trait that can be used for high-quality milk production, respectively. The fundamental understanding of the role of rumen microbiome and its metabolome contributing to milk yield and protein yield traits can provide novel insights into future manipulation of rumen microbiome to enhance milk production and quality.

Genetic analysis of phenotypic indicators for heat tolerance in crossbred dairy cattle

Climate change-induced rise in global temperatures has intensified heat stress on dairy cattle and is contributing to the generally observed low milk productivity. Selective breeding aimed at enhancing animals’ ability to withstand rising temperatures while maintaining optimal performance is crucial for ensuring future access to dairy products. However, phenotypic indicators of heat tolerance are yet to be effectively factored into the objectives of most selective breeding programs. This study investigated the response of milk production to changing heat load as an indication of heat tolerance and the influence of calving season on this response in multibreed dairy cattle performing in three agroecological zones Kenya. First-parity 7-day average milk yield (65 261 milk records) of 1 739 cows were analyzed. Based on routinely recorded weather data that were accessible online, the Temperature-Humidity Index (THI) was calculated and used as a measure of heat load. THI measurements used represented averages of the same 7-day periods corresponding to each 7-day average milk record. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: slope of the reaction norm (Slope) and its absolute value (Absolute), reflecting changes in milk yield in response to the varying heat loads (THI 50 and THI 80). The genetic parameters of these indicators were estimated, and their associations with average test-day milk yield were examined. There were no substantial differences in the pattern of milk yield response to heat load between cows calving in dry and wet seasons. Animals with ≤50% Bos taurus genes were the most thermotolerant at extremely high heat load levels. Animals performing in semi-arid environments exhibited the highest heat tolerance capacity. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero (P < 0.05). Slope at THI 80 had high (0.64–0.71) negative correlations with average daily milk yield, revealing that high-producing cows are more vulnerable to heat stress and vice versa. A high (0.63–0.74) positive correlation was observed between Absolute and average milk yield at THI 80. This implied that low milk-producing cows have a more stable milk production under heat-stress conditions and vice versa. The study demonstrated that the slope of the reaction norms and its absolute value can effectively measure the resilience of crossbred dairy cattle to varying heat load conditions. The implications of these findings are valuable in improving the heat tolerance of livestock species through genetic selection.

Особливості епізоотологічного нагляду та контролю за мікобактеріозами продуктивних тварин в умовах молочнотоварних господарств України

The increase in mycobacteriosis, an infectious disease caused by non-tuberculous mycobacteriosis, has become an urgent issue for humane medicine. The mycobacteriosis of animals is a subject of intense study by veterinary scientists across most countries globally. In Ukraine, the number of farms with productive animals exhibiting paraallergic reactions to tuberculin is steadily rising, making the diagnosis of tuberculosis more complicated. In dairy cattle breeding, this issue also has significant economic implications. The forced slaughter of breeding young stock and high-producing cows is often a consequence. On the other hand, the identification of various non-tuberculous mycobacteria species in human mycobacteriosis patients, which can sensitize the cows, gives the issue of preventing animal mycobacteriosis both medical and social significance. All of the factors mentioned previously led to the decision to permanently retain cows that react positively to tuberculin testing on a dairy farm in the Volyn region, which has historically been free of tuberculosis. A comprehensive study was conducted from 2018 to 2023, utilizing methods of epizootological analysis as well as clinical, pathological, histological, bacteriological, and statistical research techniques. It was shown that an epizootic process, caused by the infection of cattle with non-tuberculosis mycobacteria, is occurring on the dairy farm. Mycobacterium scrofulaceum, M. fortuitum, and Nocardia spp. were isolated and identified from the lymph nodes and lymphoid tissue of the large intestine submucosa in the infected animals. These pathogens cause significant histological and pathological changes, indicating the presence of a clinically covert infectious process accompanied by sensitization of the animal organism. Epizootological analysis of the results from simultaneous allergic testing, as well as multiple bacteriological studies of samples from animals that reacted positively to both purified protein derivate tuberculin and atypical mycobacteria allergens, established that the allergic reactions to tuberculin were paraallergic in nature. This indicated the presence of an active infectious process within the animals’ bodies.

Replacing conventional concentrates with sprouted barley or wheat: Effects on lactational performance, nutrient digestibility, and milk fatty acid profile in dairy cows

Finite natural resources, rising human population, and climate change pose challenges to traditional crop production. Hydroponically grown fodder (i.e., sprouted grains) can be an alternative feed source for dairy cows; however, only sprouted barley has been investigated in low-producing cows. We aimed to evaluate the effect of replacing conventional concentrates with sprouted barley or wheat, grown using hydroponics, on milk production, nutrient digestibility, and milk fatty acid profile in high-producing cows. Twenty-four multiparous Holstein cows (3.25 ± 1.33 lactations; 102 ± 23 DIM; 49 ± 4 kg/d of milk) were used in a replicated 3 × 3 Latin square design with 21-d experimental periods. Following a 2-wk covariate period, cows were fed 1 of 3 experimental diets: a TMR (1) without sprouted grains (control), or with (2) 10% sprouted barley, or (3) 10% sprouted wheat on a DM basis. Experimental diets were formulated to be isoenergetic and isonitrogenous with sprouted grains that replaced ground corn, soybean meal, canola meal, and dextrose. Sprouted grains were grown using a semi-automatic hydroponic system and harvested after 6 d of growth. Data and sample collection occurred during the last 3 d of the covariate and experimental periods. Wide ranges were observed for the DM percent of sprouted grains (12.1%-22.9% and 13.3%-25.7% for barley and wheat, respectively) and the ratio of sprouted fodder to seed (0.67-1.07 for both barley and wheat). Feeding sprouted grains did not modify the yield of milk or ECM; however, DMI were lower for barley, relative to control. Feed efficiencies were greater for barley than for control (1.49 ± 0.03 vs. 1.43 ± 0.03 for milk yield/DMI; 1.85 ± 0.03 vs. 1.73 ± 0.04 for ECM/DMI). Yields and concentrations of milk components (i.e., fat, true protein, and lactose) were not affected by treatment. Milk urea N concentrations were greater for wheat, relative to control or barley. Body weight (752 ± 3 vs. 742 ± 3 kg) and BW gains (6.53 ± 2.99 vs. -9.33 ± 2.91 kg/21 d) were higher for wheat than for control. Apparent total-tract digestibility of organic matter was greater for wheat relative to barley. Digestibilities of NDF and starch were higher for wheat and control, relative to barley, and CP digestibility was greater for wheat, relative to barley and control. Rumination and physical activity were not affected by treatment. In summary, replacing traditional concentrates with sprouted grains grown using hydroponics improved milk production efficiency (barley sprouts) or enhanced body weight gain (wheat sprouts). A life-cycle assessment needs to be conducted to determine the net effect of this feeding strategy for the dairy industry.

МАТЕМАТИЧЕСКАЯ МОДЕЛЬ ЖИВОТНОГО В БИОМАШИННОЙ СИСТЕМЕ: ПРАКТИЧЕСКОЕ ИСПОЛЬЗОВАНИЕ

Due to automated biomachine’s systems on dairy farming, in particular, robotic milking lines appearing, the problem of machinery and animals’ connections and mutual influence study has become relevant. In this case, an animal - is the biomachine system’s main link. The most important characteristic of an animal as biomachine system’s element is the dependence of its production on any factors during the technological process acting. At animals in biomachine systems using, one of the main factors determining the dairy cattle breeding profitability is balanced feed taking into account modern standards’ requirements, and modern functional balance additives in ration using. The prediction one of the feed’s options effectiveness as a new technical solution, in order to its development feasibility assessment and then implementation was carried out by animal production mathematical modeling obtained from the cows’ dry feed additives using. Its recipe the following ingredients: fullfat milk thistle’s seeds as a filler, biologically active substances - as vitamin E, probiotic and betaine using. At each other interacting, they cause a synergistic effect and were sharply needed by high production cows. This experimental additive’s recipe by weight% is: milk thistle’s crushed grain - 92,76; profort - 6,00; betaine hydrochloride (97%) is 1,20; vitamin E (50%) in loose- 0,04 is given. This preparation’s active substance amount in percentage showing. The developed additive in dry cows’ ration at 0,4 kg of dose per head per day was tested. Its use made it possible the cows’ milk production in 4,3% increasing. The animals had had feed additive, calving was easier and the body condition to normal faster had restored. The feed additive based on milk thistle grains and biologically active substances in dry cows’ feed of using had a positive effect on the technological process’s final result.

Climatização em área de alimentação de vacas Girolando: Interferências nas variáveis ambientais e produtivas

ABSTRACT High-production cows require facilities providing comfortable environments to enhance production efficiency and sustain milk quality. This study evaluated the impact of climatizing the feeding area post-morning and afternoon milking on environmental variables, thermal comfort indices, and the yield and quality of milk in lactating Girolando cows. The experiment followed a 4 × 4 Latin square design with four treatments across four experimental periods, using four cows per treatment. The post-milking climate control treatments included: shading; shading + ventilation; shading + ventilation + shower; and an evaporative adiabatic cooling system. The evaporative adiabatic cooling system proved most effective in maintaining thermal conditions near the comfort level for dairy cows, as indicated by lower thermal comfort indices. This system also enhanced morning and overall milk production. However, the climate control systems did not significantly affect the contents of protein, fat, or lactose in the milk.

Genetic analysis of lactation consistency in U.S. Holsteins using temporal variation in daily milk weights

The ability of a dairy cow to perform reliably over time is an interesting trait to include in dairy cattle breeding programs aimed at improving dairy cow resilience. Consistency, defined as the quality of performing as expected each day of the lactation, could be highly associated with resilience, defined as animal's ability to maintain health and performance in the presence of environmental challenges, including pathogens, heat waves, and nutritional changes. A total of 51,415,022 daily milk weights collected from 2018 to 2023 were provided for 255,191 multiparous Holstein cows milked 3 times daily in conventional parlor systems on farms in 32 states. The temporal variance (TempVar) of milk yield from 5 to 305 d postpartum was computed as the log-transformed variance of daily deviations between observed and expected individual milk weights. Lower values of TempVar imply smaller day-to-day deviations from expectations, indicating consistent performance, whereas larger values indicate inconsistent performance. Expected daily milk weights were computed using 3 nonparametric and parametric regression models: 1) LOESS regression with a 0.75 span; 2) polynomial quantile regression using the median (0.5 quantile), and 3) polynomial quantile regression using a 0.7 quantile. The univariate statistical model included age at first calving and herd-year-season as fixed effects and cow as a random effect. Heritability estimates (standard errors) of TempVar phenotypes calculated over the entire lactation ranged between 0.227 (0.011) and 0.237 (0.011), demonstrating that cows are genetically predisposed to display consistent or inconsistent performance. Estimated genetic correlations calculated using a multiple trait model between TempVar traits and between lactations were high (>0.95), indicating TempVar is repeatable across lactations and robust to the model used to compute expected daily milk yield. Higher TempVar phenotypes reflect more variation in performance, hence greater inconsistency, which is undesirable. Therefore, correlations between predicted transmitting abilities (PTAs) for TempVar and milk yield of 0.57 indicate that high-producing cows exhibit more day-to-day variation in performance. Correlations with productive life and livability were -0.38 and -0.48, respectively. Correlations between PTAs for TempVar and those of postpartum health traits were also negative, ranging from -0.41 to -0.08. Given that health traits are derived from disease resistance measurements, and higher health trait PTAs are preferred, our results indicate that more consistent cows tend to have fewer health problems and greater longevity. Overall, our findings suggest that temporal variation in daily milk weights can be used to identify consistent animals that maintain expected performance throughout the lactation, which will enable selection for greater resilience to management and environmental perturbations.

Impact of parity number, milk production and somatic cell count on the reproduction of Holstein cows.

This research communication describes the reproductive and productive parameters and somatic cell count (SCC) of primiparous and multiparous cows from specialized dairy Holstein herds in South region of Brazil, and correlates these parameters using test-day records. A total of 24 011 records of animals from 75 producers obtained between 2017 and 2018 were used. The variables analyzed included milk production, SCC, milk fat, protein and urea nitrogen contents and reproductive characteristics (number of services per conception, service period and percentage of pregnant cows). Data were analyzed using multivariate logistic regression and the statistical differentiation between the classes of SCC and milk production. Milk production, SCC, number of services per conception and service period were all higher in multiparous cows. The percentage of pregnant cows was higher when the SCC was less than 200 000 cells/ml and was higher in primiparous cows. There was no adverse effect of milk production on reproductive parameters in high producing cows (>40 kg milk/d), however, the percentage of pregnant cows with this production level was significantly higher in multiparous cows. In conclusion, the milk production level need not affect the reproduction of specialized dairy cows if the animals are kept under adequate environmental conditions.

Normalization of protein and carbohydrate nutrition for high productive cows during a dry period

The article provides the results of study of protein and carbohydrate nutrition for high productive cows with milk yield of 10 thousand kg during dry period. There has been carried out the research for determining the feed protein disintegration and effectiveness of its use in cow rations. The carbohydrate nutrition for Holstein-Kholmogory cows during dry period taking into account quantity and quality of neutral detergent fiber (NDF) and acid detergent fiber (ADF) was studied. The science-economic experiment was conducted in the “Polyarnaya Zvezda”, Murmansk region in 2015 and 2021. The disintegration of feed crude protein (DP) was determined by the in sacco method, by incubation of average samples of single feeds in nylon bags in the rumen during 12 hours. Content of crude protein in feed samples before and after incubation was determined by the content of total nitrogen by the Kjeldahl method. Digestibility in the intestine of feed protein not disintegrated in rumen was determined by the mobile synthetic bag method. NDF and ADF were determined by the method of Van Soest and Southgate modified by N. N. Semina. In the experiment of protein nutrition, the content of crude protein in the ration of control and experimental groups of cows was 16 %. The content of disintegrated protein in the control group was 59.0 %, in the experimental group – 67.0 %. In the experiment of carbohydrate nutrition, in the control group crude fiber was 19.4 %, neutral detergent fiber – 38.9 %, acid detergent fiber – 23.0 % of dry matter. In the ration of experimental group of cows, the content of crude fiber was 22.4 %, neutral detergent fiber – 47.2 %, acid detergent fiber – 27.6 %. Animals of the experimental group whose ration had a crude protein disintegration of 67.0% used nitrogen more efficiently, utilized a nutritious of ration better. During the research it has been established, that the content of neutral detergent fiber of up to 47.2 % and acid detergent fiber of up to 27.6 % results in increase in digestibility of ration nutritious, improves nitrogen metabolism, intensify microbiological activity in cow rumen.

Invited Review: Increasing Milk Yield and Negative Energy Balance: A Gordian Knot for Dairy Cows?

The continued increase in milk production during the last century has not been accompanied by an adequate dry matter intake (DMI) by cows, which therefore experience a negative energy balance (NEB). NEB is low and of minor importance at low milk yield (MY), such as for the nutrition of one calf, and under these circumstances is considered "natural". MY and low DMI around parturition are correlated and are the reason for the genetic correlation between increasing MY and increasing NEB up to 2000 MJ or more for 2-3 months postpartum in high-genetic-merit dairy cows. The extension and duration of NEB in high-producing cows cannot be judged as "natural" and are compensated by the mobilization of nutrients, particularly of fat. The released non-esterified fatty acids (NEFAs) overwhelm the metabolic capacity of the cow and lead to the ectopic deposition of NEFAs as triglycerides (TGs) in the liver. The subsequent lipidosis and the concomitant hampered liver functions cause subclinical and clinical ketosis, both of which are associated with "production diseases", including oxidative and endoplasmatic stress, inflammation and immunosuppression. These metabolic alterations are regulated by homeorhesis, with the priority of the physiological function of milk production. The prioritization of one function, namely, milk yield, possibly results in restrictions in other physiological (health) functions under conditions of limited resources (NEB). The hormonal framework for this metabolic environment is the high concentration of growth hormone (GH), the low concentration of insulin in connection with GH-dependent insulin resistance and the low concentration of IGF-1, the so-called GH-IGF-1 axis. The fine tuning of the GH-IGF-1 axis is uncoupled because the expression of the growth hormone receptor (GHR-1A) in the liver is reduced with increasing MY. The uncoupled GH-IGF-1 axis is a serious impairment for the GH-dependent stimulation of gluconeogenesis in the liver with continued increased lipolysis in fat tissue. It facilitates the pathogenesis of lipidosis with ketosis and, secondarily, "production diseases". Unfortunately, MY is still increasing at inadequate DMI with increasing NEB and elevated NEFA and beta-hydroxybutyric acid concentrations under conditions of low glucose, thereby adding health risks. The high incidences of diseases and of early culling and mortality in dairy cows are well documented and cause severe economic problems with a waste of resources and a challenge to the environment. Moreover, the growing public concerns about such production conditions in agriculture can no longer be ignored.

Effect of monensin on milk production efficiency and milk composition in lactating dairy cows fed modern diets

Since the US Food and Drug Administration's approval of monensin in 2004, significant nutritional advances have been made to increase feed efficiency and milk fat production. Recent evidence suggests monensin's adverse effect on milk fat percentage may be absent when diets are formulated to address known diet-induced milk fat depression risk factors. Thus, study objectives were to evaluate effects of monensin level on dry matter intake (DMI), milk production and composition, and efficiency of high-producing cows fed diets formulated to optimize milk fat. Ninety-six lactating Holstein cows (36 primiparous, 60 multiparous; 106 ± 17 d in milk [DIM]) were balanced by parity, DIM, and milk production and were randomly assigned to 1 of 12 pens with 8 cows per pen. All cows received 11 g/t monensin for 5 wk after which pens received 1 of 4 dietary treatments (n = 3) formulated to provide 0 (CON), 11 (R11), 14.5 (R14.5), or 18 (R18) g/t monensin for 9 wk. The basal diet was 54% forage, 27% NDF, 29% starch, and 2.3% rumen unsaturated fatty acid load. Pen was the experimental unit and data were analyzed using the Fit Model Procedure of JMP. Effects of treatment, time, and treatment × time interaction were included as fixed effects and pen as a random effect. Least squares means were determined and linear and quadratic contrasts were tested. Dry matter intake tended to decrease linearly with increasing monensin dose. Milk yield, fat percentage, and protein percentage and yield were unaffected by treatment while fat yield was quadratically increased. Milk de novo and mixed fatty acid (FA) yields (g/d) increased quadratically with monensin whereas preformed FA linearly decreased during the experimental period. Energy-corrected milk (ECM) was quadratically increased by monensin. Milk urea nitrogen concentrations increased linearly with increasing monensin dose. Monensin linearly increased feed efficiency (ECM/DMI, 3.5% fat-corrected milk/DMI, and solids-corrected milk/DMI). Body weight gain did not differ between treatments. Estimated dietary energy tended to increase linearly with increasing monensin level. These data suggest monensin improves component-corrected milk production efficiency, estimated dietary energy, and does not negatively affect milk fat percentage or FA profile.

Effects of grazing management and concentrate supplementation on intake and milk production of dairy cows grazing orchardgrass

In pasture-based dairy systems, grazing management strategies have focused mainly on achieving a high herbage harvest per hectare, whereas strategies oriented to maximizing the intake rate of herbage have been recently explored. The objectives of the study were (i) to evaluate the herbage nutritional value, intake and milk production per animal and per hectare of mid-lactation Holstein dairy cows grazing orchardgrass (Dactylis glomerata) in response to grazing management strategies that prioritize either herbage harvest per hectare or herbage intake rate, and (ii) to assess whether concentrate supplementation affects this response. The experiment was conducted in Uruguay using twenty-four mid-lactation Holstein dairy cows grazing orchardgrass under rotational stocking over an 81-day period. The experimental design was a randomized complete block with a 2 × 2 factorial arrangement consisting of two grazing management strategies [i.e. “high intake rate” (HIR) with pre- and post-grazing sward target heights of 21 and 13 cm, respectively, vs. “high herbage harvest per hectare” (HHH) with a pre-grazing target of 3.5–4 leaves per tiller and a post-grazing target of minimum leaf area corresponding to sward heights between 7 and 11 cm] in combination with concentrate supplementation levels of 0 (CS0) or 4 (CS4) kg of dry matter/cow per day. Sward height, number of leaves, herbage morphological and chemical composition, body weight (BW), body condition score (BCS), feed intake, and milk production per cow and per hectare were measured. Statistical analyses were performed using linear mixed models. Compared to cows under HHH, cows under HIR grazed herbage with greater nutritional value and achieved a greater feed intake and greater milk production per cow (P < 0.05), regardless of concentrate supplementation level. Conversely, under HHH milk production per hectare was marginally greater (P < 0.10) and milk solids production per hectare was greater (P < 0.05). Yet, cows under HHH lost BCS when were managed without supplementation (P < 0.05). In conclusion, HIR grazing management is an effective option for grazing dairy production systems that seek to maximize individual productivity of high-producing cows. On the other hand, HHH grazing strategies remain relevant to dairy farm businesses in which profit is driven by production per hectare. Yet, high producing dairy cows under this strategy are likely to lose BCS if not supplemented.

Comparation of moist heating and formaldehyde protein protection methods and their impact on dairy ration fermentability and digestibility

Improving protein efficiency has become the main target in dairy farming. The feeding strategy for high-producing cows is directed by optimizing non-protein nitrogen utilization while maintaining post-ruminal digested bypass protein. Soybean and soybean meal are protein sources with high biological value but are highly degradable, so they must be protected. This study aimed to compare the effect of moist heating and formaldehyde treatments as a method for protecting protein to increase rumen bypass protein. Parameters observed include fermentation profile (rumen pH, NH3, total VFA, protozoa, and total bacteria population) and nutrient digestibility. Treatments tested were an unprotected diet as control (C1), moist heating protected protein (C2), and formaldehyde protected protein (C3). Data were subjected to ANOVA using Randomized Block Design followed by orthogonal contrasts. The results showed that both moist heating and formaldehyde treatments (C2 and C3) reduced NH3 and total VFA concentration (p<0.05) without affecting rumen pH, protozoa, and total bacteria count (p>0.05). Dry matter and organic matter did not affect by the treatments. In conclusion, both moist heating and formaldehyde methods could be used to protect feed protein and improve bypass protein in the dairy ration.

The effect of FGF21 gene polymorphism (g. 940C/T) on biochemical metabolic parameters in blood serum of holstein cattle

The study examined the effect of polymorphism of the fibroblast growth factor 21 gene (Bos taurus FGF21 g.940 C/T) on the level of FGF21 and biochemical metabolic parameters in blood serum of highproducing cows. DNA genotyping of 148 animals of Holstein cows was performed by a PCR-RFLP method. As a result of genotyping, two FGFC – 0.642 and FGFT – 0.358 alleles as well as two FGFCC – 28.4% (42 animals) and FGFTC – 71.6% (106 animals) genotypes were identified. Individuals with the FGFTT genotype were not identified. The obtained data show that the seroen zyme FGF21 level is statistically significantly higher in cows with the FGF21CC genotype than in cows of the heterozygous genotype by 165.5 pg/ml (28.2%; p &lt; 0.001). Analysis of the association between the polymorphism of the FGF21 gene and the level of fibroblast growth factor 21 suggests that the activity of this enzyme changes depending on the genotype, as a result of which there is a variation in serum biochemical parameters of Holstein cattle.

Comparative assessment of the dynamics of milk productivity of black and white holstinized breed cows over five years on a farm in the Leningrad region

The current work analyses dynamics and key indicator changes in milk productivity and development in a livestock of 857 first heifers in a breeding cattle farm in Leningrad Region between 2017 and 2021. In the five years the share of high-producing animals (over 10000 kg of milk per. 305 days) in the first lactation period increased. A growth in milk fat and protein levels and increased milk yield rate were also witnessed. Mass fraction of fat increased 0.03% by 2021 compared to 2017. Mass fraction of protein gradually increased over the five years and was 3.22% by 2021, up 0.06% from 2017. The amount of milk fat increased by 6%, and the amount of protein also gradually increased, and by 2021 was 7.6% higher than the initial figure. There was a slight decreased in a first-heifer weight (by 2.8%). The share of first-heifers with milk production above 10000 kg per lactation increased by 18.5% from 2017 to 2021, and the yield increased by 6%. There is a correlation between the milk yield and the number of high producing cows yielding over 10000 kg during a lactation period. A comparative evaluation with the standard of the breed showed that the average milk production exceeded the standard by 111%, the mass fraction of fat – 115%, the mass fraction of protein – 0.18%, the amount of milk protein – 133.6%, the development (weight) – 23%. The collected data signify focused selection work carried out in the farm and are likely to result from the use Holstein bull-improvers.

Genetic Polymorphism and mRNA Expression Studies Reveal IL6R and LEPR Gene Associations with Reproductive Traits in Chinese Holsteins

Genetic selection of milk yield traits alters the energy distribution of high producing cows, resulting in gene-induced negative energy balance, and consequently, poor body condition scores and reduced reproductive performances. Here, we investigated two metabolic-syndrome pathway genes, IL6R (Interleukin 6 receptor) and LEPR (Leptin receptor), for their polymorphism effects on reproductive performance in dairy cows, by applying polymorphism association analyses in 1588 Chinese Holstein cows (at population level) and gene expression analyses in granulosa cells isolated from eight cows (at cell level). Among the six single nucleotide polymorphisms we examined (two SNPs for IL6R and four SNPs for LEPR), five were significantly associated with at least one reproductive trait, including female fertility traits covering both the ability to recycle after calving and the ability to conceive and keep pregnancy when inseminated properly, as well as calving traits. Notably, the identified variant SNP g.80143337A/C in LEPR is a missense variant. The role of IL6R and LEPR in cattle reproduction were further confirmed by observed differences in relative gene expression levels amongst granulosa cells with different developmental stages. Collectively, the functional validation of IL6R and LEPR performed in this study improved our understanding of cattle reproduction while providing important molecular markers for genetic selection of reproductive traits in high-yielding dairy cattle.

Selective dry-cow therapy can be implemented successfully in cows of all milk production levels

Antibiotic stewardship on dairy farms can be heightened through the implementation of selective dry-cow therapy (SDCT). However, some producers are concerned that this practice may be related to poor udder health outcomes in cows with high milk production at the time of dry-off. The objective of this study was to evaluate if the effect of culture-guided SDCT (Cult-SDCT) and algorithm-guided SDCT (Alg-SDCT) on dry-period intramammary infection (IMI) dynamics and postcalving udder health and performance [when compared with blanket dry-cow therapy (BDCT)] varied according to milk production level before dry-off. Data were compiled from clinical trials conducted in the United States and Canada that compared Cult-SDCT and Alg-SDCT to a positive control, i.e., BDCT. In those trials, cows were enrolled 1-2 d before dry-off, randomized to their dry-cow therapy strategy and followed until 120 d in milk of the subsequent lactation. The number of cows and quarters in the final data set were 1,485 and 5,097, respectively. Measured outcomes included quarter-level antibiotic use at dry-off, quarter-level IMI prevalence after calving, quarter-level dry-period IMI cure risk, quarter-level dry-period new IMI risk, cow-level clinical mastitis and removal from the herd during 1-120 d in milk, and somatic cell count and milk yield during 1-120 DIM. The primary objective of analysis was to investigate if the effect of Cult-SDCT and Alg-SDCT on these outcomes, when compared with BDCT, varied according to milk production level before dry-off. To do this, each cow was classified as having low, mid or high production, based on her milk yield tertile group at the most recent herd test before enrollment (low: <23.7 kg/d, mid: 23.7 to 30.4 kg/d, and high >30.4 kg/d). Multivariable generalized estimating equations were used to estimate risk differences and differences in means, and Cox regression was used to estimate hazard ratios. For Cult-SDCT, the proportion of quarters treated with dry-cow antibiotics within each milk production level were 40.7% (low), 41.7% (mid) and 47.2% (high). For Alg-SDCT, the proportions were 60.6% (low), 38.7% (mid), and 35.1% (high). Measures of udder health were not markedly different when comparing Cult-SDCT to BDCT and Alg-SDCT to BDCT. This was consistently observed in low, mid and high producing cows. In conclusion, the findings from this study indicate that Cult-SDCT and Alg-SDCT can be successfully implemented in cows of all milk production levels.

Additive “PREVAX” application for mastitis prevention and complex treatment in high-producing cows

This article presents the results of clinical trials of the supplement “PREVAX”. The results of the additive tolerability study «PREVAX» are presented in high-producing cows, the results of preventive and therapeutic use of the supplement “PREVAX” in high-producing cows with subclinical and clinical mastitis, and the effect of the supplement on milk parameters and milk production. The application of the additive “PREVAX” for the prevention of mastitis has a positive effect. The administration of the supplement orally through the watering system at a dose of 1 ml per 100 litres of water for 60 days was found to reduce the incidence of mastitis in cows by 70%. Administration of the additive “PREVAX” to cows with the clinical form of mastitis at a dose of 4 ml per 100 litres of water in the background of classical therapy with Mamikur at a dose of 10 ml intra-cisternally is well tolerated by the animals, gives a pronounced positive clinical effect and leads to normalisation of somatic cell count in milk on the sixth day of treatment. At the same time, treatment without the supplement “PREVAX” only led to a similar result after 12 days of treatment.

The role of structural carbohydrates in feeding of cows in the conditions of the european north

The purpose of the research is to study effect of quality of neutral detergent (NDF) and acid detergent (ADF) fiber with its different content in the rations when feeding of high productive cows on the digestibility of nutrients, use of the fodder nitrogen by animals, their productivity. The experiment was carried out on Holsteined cows of the Kholmogory breed during the second phase of lactation (101-200 days) on two groups selected according to the principle of paired analogues - control and experimental, 9 heads each, with a productivity of 8-10 thousand kg per year. The ration of the control group cows corresponded to the economic one. It contained crude fiber - 18.8%, neutral detergent fiber - 42.0%, acid detergent fiber - 21.7% by dry matter. The ration of cows of the experimental group contained crude fiber - 21.7%, neutral detergent fiber - 45.0%, acid detergent fiber - 23.2%. Due to the change in the ratio of bulky feeds (hay, silage) in the ration, different levels of NDF and ADF were created. As a result of the conducted research, it was found that feeding of animal by foods with neutral detergent fiber up to 45.0% and acid detergent fiber up to 23.2%, microbiological activity in the rumen of cow is increasing, the digestibility of nutrients in the ration is increasing, nitrogen metabolism is improving. As a result milk productivity is increasing by 7.0%, milk fat by 0.08%. Maintenance of high productive cows on ration with the level of NDF - 45.0% and ADF - 23.2% makes it possible for more fully stabilization of metabolic processes in animal body, to improve the intensity of rumen digestion, and use feed efficiently. Acknowledgment: This work was carried out within the framework of the state assignment of the Ministry of Science and Higher Education of the Russian Federation on the topic No. FGER-2021-0001, registration number AAAA-A19-119011790116-7. We would like to express our gratitude to the staff of LLC "Polar Star", Murmansk Region, for their assistance in conducting the research.