Resistance Of Cows Research Articles

Distribution of bacterial pathogens and antimicrobial resistance in cows with clinical mastitis in a dairy farm, Türkiye

This study aimed to identify the pathogens causing clinical mastitis (CM) and their resistance levels to six common antimicrobials in a dairy farm in Turkey. A total of 973 CM milk samples were cultured and a Kirby-Bauer disc diffusion method was performed for antimicrobial susceptibility. While 64.0% (623/973) of CM samples were culture-positive, 36.0% (350/973) of CM samples yielded no growth. Escherichia coli was the most frequently isolated pathogen (36.3%), followed by coagulase-negative staphylococci (8.3%), Streptococcus dysgalactiae (7.3%), Staphylococcus aureus (3.1%), Streptococcus uberis (1.5%), Enterococcus spp. (1.4%), Mycoplasma spp. (1.4%), Streptococcus agalactiae (0.7%), and Corynebacterium spp. (0.4%). Antimicrobial resistance was higher (P > 0.01) to amoxicillin/clavulanic acid (AMC, 32.3%) than that to enrofloxacin (ENR, 23.4%), cefoperazone (CFP, 17.9%), cefquinome (CEQ, 17.7%), penicillin G (P, 15.2%), and gentamicin (CN, 3.6%) in culture-positive 642 isolates. For E. coli isolates, percentage of resistance to AMC, ENR, CFP, CEQ, P, and CN was 37.7, 30.6, 24.4, 23.2, 5.9, and 1.1%, respectively. Resistance to AMC (31.2%) and P (46.3%) was higher in CNS than Strep. dysgalactiae isolates (1.5% and 12.7%), respectively. Multidrug resistance was detected in 34 E. coli isolates (9.6%), 7 CNS isolates (8.6%), and 2 Strep. dysgalactiae (2.8%). In conclusion, the higher identification of E. coli demonstrated the higher risk of environmental microorganisms for CM in this study. Higher resistance to commonly used five of six antimicrobials showed the requirement of frequent bacteriological and antimicrobial susceptibility tests for CM. Thus, these implementations could increase treatment efficacy in cows and reduce antimicrobial resistance.

Body conformation traits in early-lactation associated with clinical mastitis and lameness in lactating Chinese holstein cows

BackgroundComprehending the correlation between body conformation traits of cows at the early stages of lactation and prevalent lactation diseases might facilitate the execution of selection and feeding strategies that prioritize cow health. This study aimed to evaluate the impact of body conformation traits on the incidence of clinical mastitis and lameness in Chinese Holstein cows. From a pasture herd of 1472 early lactating Chinese Holstein cows, we evaluated 20 body conformation traits. During lactation, this pasture herd was visited weekly to gather clinical mastitis and lameness data. A nine-point scale was used to determine the conformation traits of cows to clarify their linear characters, including frame capacity, rump (RU), feet and leg (FL), mammary system (MS), and dairy character. A longitudinal binary disease (0 = healthy; 1 = diseased) data structure was created by allocating disease records to adjacent official test dates. The impact of body conformation traits on the risk of developing diseases (clinical mastitis and lameness) was analyzed using the logistic regression models.ResultsCompared to cows with low total scores (75–79 points), those with high total scores (80–85 points) of body conformation traits had a significantly lower risk of mastitis (P < 0.001). The disease status (0 or 1: binary variable) of clinical mastitis in lactating cows was significantly impacted negatively by age (P < 0.05). The fore udder attachment (FUA), angularity, rear attachment height (RAH), and rear teat placement (RTP) were all significantly associated with clinical mastitis during lactation (P < 0.05). The rear leg-rear view (RLRV) was significantly correlated with correlated considerably (P < 0.05) with lameness during lactation. An ideal score of four points on the lameness risk dimension of the RLRV may indicate a low risk of lameness. Since the risk of mastitis decreased as this trait score increased, the RTP may be an ideal marker for mastitis risk.ConclusionsAccording to the study, clinical mastitis and lameness risks in cows can be estimated using their body conformation traits. Cows with more centrally located rear teats have a lower risk of mastitis. These results may help dairy farmers identify cows at high risk of disease early in lactation and aid in breeding for disease resistance in cows.

ZEA mediates autophagy through the ROS-AMPK-m-TOR pathway to enhance the susceptibility of mastitis induced by Staphylococcus aureus in mice

Mastitis is an inflammatory response of the mammary tissue caused by pathogenic bacterial infections, especially Staphylococcus aureus (S. aureus). Zearalenone (ZEA) is one of the common mycotoxins in moldy feed, which usually affects the cow's resistance to pathogenic microorganisms. However, it is not well understood whether ZEA affects the development of mastitis. Therefore, this study aimed to investigate the role of ZEA in the development of S. aureus-induced mastitis in mice. The results showed that administered daily by gavage for one week of ZEA (40 mg/kg) aggravated the severity of mastitis induced by S. aureus. Furthermore, we found that ZEA promotes the adhesion and invasion of S. aureus into mouse mammary epithelial cells (MMEC) by activating autophagy, and the activation of autophagy mediated by ROS-AMPK-m-TOR pathway. Taken together, the results showed that ZEA enhances S. aureus-induced mastitis susceptibility through activating autophagy mediated by ROS-AMPK-mTOR signaling pathway.

Altered Fecal Microbiome and Correlations of the Metabolome with Plasma Metabolites in Dairy Cows with Left Displaced Abomasum.

Left displaced abomasum (LDA) in postpartum dairy cows contributes to significant economic losses. Dairy cows with LDA undergo excessive lipid mobilization and insulin resistance. Although gut dysbiosis is implicated, little is known about the role of the gut microbiota in the abnormal metabolic processes of LDA. To investigate the functional links among microbiota, metabolites, and disease phenotypes in LDA, we performed 16S rDNA gene amplicon sequencing and liquid chromatography-tandem mass spectrometry (LC-MS/MS) of fecal samples from cows with LDA (n = 10) and healthy cows (n = 10). Plasma marker profiling was synchronously analyzed. In the LDA event, gut microbiota composition and fecal metabolome were shifted in circulation with an amino acid pool deficit in dairy cows. Compared with the healthy cows, salicylic acid derived from microbiota catabolism was decreased in the LDA cows, which negatively correlated with Akkermansia, Prevotella, non-esterified fatty acid (NEFA), and β-hydroxybutyric acid (BHBA) levels. Conversely, fecal taurolithocholic acid levels were increased in cows with LDA. Based on integrated analysis with the plasma metabolome, eight genera and eight metabolites were associated with LDA. Of note, the increases in Akkermansia and Oscillospira abundances were negatively correlated with the decreases in 4-pyridoxic acid and cytidine levels, and positively correlated with the increases in NEFA and BHBA levels in amino acid deficit, indicating pyridoxal metabolism-associated gut dysbiosis and lipolysis. Changes in branched-chain amino acids implicated novel host-microbial metabolic pathways involving lipolysis and insulin resistance in cows with LDA. Overall, these results suggest an interplay between host and gut microbes contributing to LDA pathogenesis. IMPORTANCE LDA is a major contributor to economic losses in the dairy industry worldwide; however, the mechanisms associated with the metabolic changes in LDA remain unclear. Most previous studies have focused on the rumen microbiota in terms of understanding the contributors to the productivity and health of dairy cows; this study further sheds light on the relevance of the lower gut microbiota and its associated metabolites in mediating the development of LDA. This study is the first to characterize the correlation between gut microbes and metabolic phenotypes in dairy cows with LDA by leveraging multi-omics data, highlighting that the gut microbe may be involved in the regulation of lipolysis and insulin resistance by modulating the amino acid composition. Moreover, this study provides new markers for further research to understand the pathogenesis of the disease as well as to develop effective treatment and prevention strategies.

Dynamics of indicators of non-specific resistance in cows with genital Mycoplasmosis on the background of therapy with Tulathromycin

Modern livestock breeding technologies imply the maximum use of the productive potential of animals. Animal diseases of various etiologies are a significant obstacle to the fulfillment of this task, causing significant economic damage, consisting of a shortage of products, restrictions on its sale and treatment costs. One such disease is genital mycoplasmosis in cattle. The aim of our research was to study the effect of treatment of genital mycoplasmosis in cows with tulathromycin on some indicators of nonspecific resistance. Studies were carried out on two groups of pregnant cows, a group of animals with mycoplasmosis was treated with tulathromycin, healthy cows served as controls. In both groups of animals, the activity of lysozyme, bactericidal activity of blood serum, phagocytic activity and phagocytic index were determined. It has been established that the use of tulathromycin leads to the recovery of 75% of infected cows, and also leads to an increase in phagocytosis, which does not significantly differ from the level of healthy animals. To a lesser extent, the use of this drug in genital mycoplasmosis affects the bactericidal and lysozyme activity of blood serum.

Study of the resistance of cows with mastitis depending on the age of lactation

Relevance.The breeding stock and young cattle in the conditions of industrial technology of animal husbandry experience an increased antigenic load, which leads to disturbances in the immune status and the development of inflammatory processes manifested by endometritis and mastitis, diarrheal and respiratory syndromes. It was relevant to conduct a comprehensive assessment of the immunological reactivity of the animal’s body according to the state of resistance in cattle with clinical and subclinical mastitis, depending on the age of lactation. As a result of complex studies, the specific and nonspecific reactivity of the body of cattle in different periods of lactation was studied.Methods.The object of the study were cows of a black-and-white Holstein breed (n = 450). Groups of animals were formed according to the age of lactation:1st lactation, 2–3rd lactation, 3–4th lactation and for health reasons: clinically healthy animals, with subclinical mastitis and clinical mastitis. Milk samples were taken from cows to count the number of somatic cells, and blood to determine the quantitative content of IgG immunoglobulin and indicators of nonspecific resistance.Results.It was found that with mastitis in cows of different lactation ages, almost identical changes in the immune status were observed. Quantitative determination of IgG levels in animal blood serum is the basis for assessing the immunity of cattle. The immune status in clinically healthy animals was characterized by a higher level of the total amount of IgG immunoglobulin in the blood serum (amounted to 22.25 ± 0.70 mg/ml), whereas in cows with a subclinical form of mastitis, the level of IgG immunoglobulin decreased by 12.3%, with a clinical form of mastitis — by 17.2%. The results also showed that in cows of different lactations with subclinical and clinical mastitis, the bactericidal activity (by 10.8%) and the lysozyme activity of the blood increased significantly (by 8.22%). In cows with clinical mastitis — by 8.6% and 9.7% respectively, compared with the indicators in groups of healthy animals. Thus, mastitis, occurring in acute and subacute form, leads to a decrease in the resistance of the cows’ organism.

Obtaining organic dairy products using common thyme as antibiotic replacing therapy of endometritis in cows

According to the Federal Law of August 3, 2018 No. 280-FZ organic agriculture is referred to as total economic activity that enables the development of ways, methods and technologies that promote favorable state of the environment and improve human health. The need for this law is dictated by the data of the Research Institute of Nutrition of the Russian Academy of Sciences, which claim that 30-50% of all diseases of Russians arise from the consumption of poor-quality food. 30% of the pollution of the world ecosystem refer to an agricultural sector, which is an obvious need for the greening of agriculture and the production of organic products. Organic products mean environmentally friendly agricultural products, raw materials and food in the production of which the following requirements are met: the use of agrochemicals is prohibited, pesticides and antibiotics, growth stimulants are absent, and hormones are not used in animal fattening. Taking into account Russian legislation, the products of dairy cattle breeding should not indicate the presence of oxytetrocycline, levomycetine, streptomycin, tetracycline, ampicillin, penicillin, grisin, bacitrocin. Natural resistance in cows is reduced as a result of negative factors (stress factors) characterizing the industrial technology for the production of livestock products itself, and negative environmental factors. Currently, the development of dairy cattle breeding and the increase in animal productivity are restrained by the high incidence of diseases of the reproductive organs, among which a significant part are inflammatory diseases of the genitals, in particular endometritis (up to 90% of the total number of calving cows). The use of herbal preparations in folk and traditional veterinary science and medicine makes it relevant to search for new plants for obtaining medicinal raw materials in the treatment and prevention of endometritis. Common thyme is proposed as such. The article shows the results of using common thyme for cows with endometritis as antibiotic replacement therapy, which confirmed by an increase in a number of biochemical blood indicators and the overall health of animals.

Biomarkers of natural resistance in caws with deficiency of vitamins A and E

The article highlights the results of studies of the state of natural resistance in highly productive cattle with disorders of vitamin metabolism. The aim of the study was to investigate the effect of hypovitaminoses A and E of varying severity on biomarkers of natural resistance in cows. Serum from 90 cows from farms in different regions of Ukraine was used as research material. Levels of vitamins A and E in serum, the levels of some markers of innate immunity (total protein, globulins, circulating immune complexes, seromucoids, lysozyme activity) and the state of oxidative-antioxidant homeostasis (content of diene conjugates and malonic dialdehyde, catalase activity) were measured. Common methods based on spectrophotometry were used. It has been found that in highly productive cows with vitamin A and E deficiency compared to animals with normal physiological level of vitamins, there are shifts in the markers of natural resistance. Thus, severe hypovitaminoses A and E (decrease by 64.4% and 37.5% respectively) is accompanied by a probable increase in globulins, circulating immune complexes and seromucoids by 50.0–71.4%, as well as a decrease in catalase activity and accumulation of lipid peroxidation products by 21.1–28.5%. With vitamin A and E deficiency at the level of 26.4% and 2.5% respectively, there is an increase in the level of globulins (by 24.5%) and less pronounced changes (by 18.6–26.4%) of a similar orientation in the system of lipid peroxidation-antioxidant protection. The decrease in the level of vitamin A in the blood serum of cows by 34% is accompanied only by an increased accumulation of malonic dialdehyde by 20.7%. Lysozyme activity was reduced in animals of all experimental groups with vitamin A and E deficiency, but the degree of its changes did not depend on the severity of hypovitaminoses

ПРОДУКТИВНОЕ ДОЛГОЛЕТИЕ КОРОВ РАЗНОГО ТИПА СТРЕССОУСТОЙЧИВОСТИ

The research goal is to increase the duration of the period of productive use of cows in modern complexes for milk production. The object of research is cows of the newly created intra-breed middle Volga type of black-and-white breed, culled for various reasons from the herd in the period from 2016 to 2018. All animals for further statistical processing of the studied indicators were divided into four groups, taking into account the type of stress resistance according to the method of E. p. Kokorina in the modification described by E. N. Letyagina. It was found that all hematological indicators decrease with increasing stress resistance in cows, except for the content of white blood cells. An increase in the concentration of white blood cells in the blood by 6.8-41.9% is probably a protective reaction of the body. Different reactivity of cows to the action of stress factors has an impact on the natural resistance of their body. A decrease in BASC by 3.2-10.5% was found, LASC –&#x0D; by 3.5-9.0%, FUNK-by 1.8-7.3%. When stress resistance decreases, the concentration of immunoglobulins in the blood decreases: IgG-by 3.9 – 11.2%, IgM-by 1.1 – 22.5%, IgA-by 3.4 – 24.1%. Studies have shown that cows of the first type of stress was superior to their peers with high stress-STU life expectancy at 262,6-1264,8 day (11,6-100%; P&lt;0,05-0,001); in the long-STI period of productive use – on 0,2-2,5 lactation (4,7-125%; P&lt;0.001); the magnitude of the average milk yield per lactation on 487-2175 kg of milk (8,5-53.6 percent; P&lt;0,05-0,001); the value of lifetime milk yield –&#x0D; for 3340-19924 kg of milk (13.5-245.5%; P&lt;0.01-0.001); for milk yield per 1 day of life-0.2-4.7 kg&#x0D; (1,8-73,4%; P&lt;0,001), on the 1st day of lactation – 2,3-5,5 kg (13,9-41,4%; P&lt;0,001). It is recommended that the" breeding core " of the herd be equipped with animals of types I and II of stress resistance. When using type II stress resistance cows, additional attention should be paid to the milk productivity of their mothers when selecting breeding bulls.

CHARACTER OF LACTATION ACTIVITIES OF COWS OF DIFFERENT PRODUCTION TYPES OF THE SIMMENTAL BREED

Dairy productivity of the milking herd is one of the main indicators that characterize the effectiveness of dairy cattle breeding. Optimal internal and external factors of cow productivity are directly dependent on the dynamics of yields throughout the lactation displayed by the lactation curve. In production conditions, preference is given to cows whose yields curve is gradually increasing and decreasing evenly, what means such animals have high lactation activity. The high and steady lactation curve indicates the ability of cow withstand a long physiological load for a long time. The purpose of our work was to study the nature of lactation curves and lactation resistance in different cows’production types of Simmental breed.&#x0D; Researches were carried out in agricultural limited liability company “Litinske” of Drohobych district of Lviv oblast on Simmental cows. A sample includes 161 mature cowbanes cows with the third full lactation. The distribution of cows into production types was performed by the method, described by Z. Aysanov.&#x0D; It was found that cows' yields for 305 days of first lactation at average over the herd was 4358 kg, and in 305 days of the third lactation – 4850 kg. When dividing animals into production types we found that the highest milk yields for the studied lactation were characterized dairy cows. Lactation curves of cows of the studied production types were quite stable. They had the highest average monthly yields from the second to the fifth month of lactation, and the maximum yields were mostly in the third month.&#x0D; The heifers and mature cowbanes of dairy production type compared to the same year cows of dairy-meat and meat-dairy types have higher monthly average milk yields. The minimum difference between the average milk yield per third lactation between dairy and dairy-meat and meat-dairy production types were observed at the first months of lactation, and the maximum – in the last. This indicates that animals of dairy production type lactation curves were more stable than the same year of different types. The best lactation activity of dairy production cows is show also indices calculated by different methods.&#x0D; In particular, these animals are mostly have significantly higher values of indices of dairy constancy by H. Terner, lactation constancy by I. Yoganson and A. Hanson, the full value of lactation according to V. B. Veselovsky, A. Zhyrnov, lactation resistance according to J. I. Weller et al., lactation decline according to D. V. Elpatyevskyi and index of actation curve forms by P. Mahadevan.&#x0D; A certain dependence of lactation resistance in cows of different production types was established on their age. In particular, dairy production animals had more stable third lactation, than the first. Higher lactation resistance of dairy cows shows only half of the calculated indices, and the meat-dairy type animals had more valuable first lactation.&#x0D; The yields of the cows depends to some extent on the shape of the lactation curve. Among the animals of the production types under study, cows with a highly stable form had the highest yield lactation curve. The second position in this indicator had animals with a medium-stable lactation curve and lowest milk yields had low-stability lactation curve. However, it should be noted that significantly higher milk yields highly stable lactation curve was observed only in mature cowbanes dairy production type.&#x0D; In order to choose the best method that will most objectively allow to establish individual and group characteristics of cows by nature of lactation activity, we calculated the coefficients of correlation of yield with the indices that characterize lactation activity of cows of different production types. Correlation analysis showed that between lactation yields and indices calculated by H. Terner, V. Veselovskyi, and A. Zhirnov and J. I. Weller et al., exists mostly a positive high-quality correlation. These indexes are the most predictive about the nature of lactation activity of cows of the studied production types. The lowest values correlation coefficients, and in some places negative indices, are noted between animal yields and indices, calculated by I. Yohansson and A. Hanson, D. V. Elpatyevskyi, and P. Mahadevan.&#x0D; It is established that the character of lactation activity of cows is influenced by their belonging toproduction type. This factor both heifers and mature cowbanes had greatest affected at the constancy of the yield by H. Terner (63.7 and 32.0% of the total phenotypic variability, P &lt; 0.001), the value of lactation according to V. B. Veselovskyi and A. Zhirnov (73.4 and 34.5%, P &lt; 0.001) and lactation resistance according to J. I. Weller et al. (41.9 and 31.3%, P &lt; 0.001).

Genetic relationships of alternative somatic cell count traits with milk yield, composition and udder type traits in Italian Jersey cows.

The aim of this study was to estimate genetic associations between alternative somatic cell count (SCC) traits and milk yield, composition and udder type traits in Italian Jersey cows. Alternative SCC traits were test-day (TD) somatic cell score (SCS) averaged over early lactation (SCS_150), standard deviation of SCS of the entire lactation (SCS_SD), a binary trait indicating absence or presence of at least one TD SCC >400,000cells/ml in the lactation (Infection) and the ratio of the number of TD SCC >400,000 cells/ml to total number of TD in the lactation (Severity). Heritabilities of SCC traits, including lactation-mean SCS (SCS_LM), ranged from 0.038 to 0.136. Genetic correlations between SCC traits were moderate to strong, with very few exceptions. Unfavourable genetic associations between milk yield and SCS_SD and Infection indicated that high-producing cows were more susceptible to variation in SCC than low-producing animals. Cows with deep udders, loose attachments, weak ligaments and long teats were more susceptible to an increase of SCC in milk. Overall, results suggest that alternative SCC traits can be exploited to improve cow's resistance to mastitis in Italian Jersey breed.

Clinical and haematological indices of the cows for acute catarrhal-purulent endometritis

Postpartum inflammatory processes in the genital organs are enough common reason of prolonged symptomatic infertility, which is from 10 to 72% of the total dairy herd of cows and are often registered in the form acute endometritis. The goal of the work was to study non-specific indicators resistance in healthy and illness with catarrhal purulent endometritis of cows. The haematological tests research were carried out during the winter-spring period on cows of four groups, which were formed on the basis of analogues and on the basis of clinical and gynaecological investigations. Presented data regarding special feature of clinical signs of postnatal endometritis in cows. In cows during the puerperal period recorded acute serous of endometritis purulent-catarrhal. The acute catarrhal purulent endometritis causes in cows significant changes in the morphological composition of blood and all investigated units of natural resistance. In illness cows with compared to healthy ones pregnant cows have had an undoubted increase in haemoglobin content (by 15.4%), the number of eosinophils and neutrophils which core has rod shape; an increase in the number of leukocytes (by 8.3%) and a decrease in lymphocytes, bactericidal (10.42%) and lysozyme activity of plasma (0.96%) was not reliable. The low index of phagocytic activity for acute postpartum endometritis suggests the inhibition of phagocytosis in the body of illness cows. The acute catarrhal purulent endometritis causes in cows significant changes in the morphological composition of blood and all investigated units natural resistance. The low index of phagocytic activity for such state as acute postpartum endometritis suggests the inhibition of phagocytosis in the body of illness cows. Further work will be focused on the using of indices of non-specific resistance of cows for prediction and correction of inflammatory processes in the uterus.

Genome-wide pleiotropy and shared biological pathways for resistance to bovine pathogens

Host genetic architecture is a major factor in resistance to pathogens and parasites. The collection and analysis of sufficient data on both disease resistance and host genetics has, however, been a major obstacle to dissection the genetics of resistance to single or multiple pathogens. A severe challenge in the estimation of heritabilities and genetic correlations from pedigree-based studies has been the confounding effects of the common environment shared among relatives which are difficult to model in pedigree analyses, especially for health traits with low incidence rates. To circumvent this problem we used genome-wide single-nucleotide polymorphism data and implemented the Genomic-Restricted Maximum Likelihood (G-REML) method to estimate the heritabilities and genetic correlations for resistance to 23 different infectious pathogens in calves and cows in populations undergoing natural pathogen challenge. Furthermore, we conducted gene-based analysis and generalized gene-set analysis to understand the biological background of resistance to infectious diseases. The results showed relatively higher heritabilities of resistance in calves than in cows and significant pleiotropy (both positive and negative) among some calf and cow resistance traits. We also found significant pleiotropy between resistance and performance in both calves and cows. Finally, we confirmed the role of the B-lymphocyte pathway as one of the most important biological pathways associated with resistance to all pathogens. These results both illustrate the potential power of these approaches to illuminate the genetics of pathogen resistance in cattle and provide foundational information for future genomic selection aimed at improving the overall production fitness of cattle.

Adaptation ability and natural animals resistance of polissia meat breed

It was made the research of the adaptive ability and natural resistance of Polissia meat breed animals, the area of their content was limited by the conditions of the lowland, forested and bogged territory of the Ukrainian Polissia and Precarpathian. Materials for analysis were selected with scientific publications and works, which reflect the issue of the breeding and maintenance of Polissia meat breed animals, as well as their own research on the natural resistance of cows. As a result of the analysis of the obtained information, it was found out that the cows of the 1st experimental group of the high-growth type, they possess a high potential of natural resistance, a somewhat lower resistance was detected in the cows of the intermediate type (II control group) and compact type (III experimental group). From these studies it emerges that there is the advisability of a comprehensive study of the type of constitution, since this determines the level of natural resistance and light resistance of animals. Only strong animals are able to be healthy, to give a viable and full-fledged offspring, to have high productivity, to withstand constant operational loads on the body and for a long time to be rationally operated with the greatest economic efficiency.

Effects of niacin supplementation on the insulin resistance in Holstein cows during early lactation

Insulin resistance in early lactation includes low glucose concentration, low insulin release and responsiveness and high lipolysis. Niacin is important antilipolytic agent and leads to increase glucose and insulin concentration. The objectives of this study were to determine the influence of niacin on the insulin resistance in cows during early lactation using the difference of value and regression analysis between blood non-esterified fatty acid (NEFA), glucose and insulin concentrations, revised quantitative insulin sensitivity check index and glucose-to-insulin ratio. Niacin supplementation led to a decrease of NEFA concentration and an increase of glucose and insulin concentrations during the first three weeks after calving. Cows in the niacin group which were more resistant to insulin showed higher concentrations of non-esterified fatty acid in comparison with more sensitive cows from the same group, but still lower than the control. The regression analyses suggest the following characteristics of cows supplemented with niacin in comparison with the control group: the insulin response to glucose was more intense; the antilipolytic effect of insulin was lower; insulin efficiency expressed as glucose-to-insulin ratio increase with a decrease in NEFA. The metabolic changes due to niacin supplementation showed a dual influence on the insulin resistance in dairy cows during early lactation: decreased NEFA concentrations led to a decrease in the insulin resistance (due to an increase in insulin efficiency and insulin sensitivity index), but increased concentrations of insulin and glucose possibly caused an increase in the insulin resistance in dairy cows (due to lower insulin sensitivity index and possibly lower antilipolytic effects of insulin).

Биохимические и морфологические показатели крови и уровень естественной резистентности коров голштинской породы

Биохимические и морфологические показатели крови и уровень естественной резистентности коров голштинской породы

Generation of mastitis resistance in cows by targeting human lysozyme gene to β-casein locus using zinc-finger nucleases

Mastitis costs the dairy industry billions of dollars annually and is the most consequential disease of dairy cattle. Transgenic cows secreting an antimicrobial peptide demonstrated resistance to mastitis. The combination of somatic cell gene targeting and nuclear transfer provides a powerful method to produce transgenic animals. Recent studies found that a precisely placed double-strand break induced by engineered zinc-finger nucleases (ZFNs) stimulated the integration of exogenous DNA stretches into a pre-determined genomic location, resulting in high-efficiency site-specific gene addition. Here, we used ZFNs to target human lysozyme (hLYZ) gene to bovine β-casein locus, resulting in hLYZ knock-in of approximately 1% of ZFN-treated bovine fetal fibroblasts (BFFs). Gene-targeted fibroblast cell clones were screened by junction PCR amplification and Southern blot analysis. Gene-targeted BFFs were used in somatic cell nuclear transfer. In vitro assays demonstrated that the milk secreted by transgenic cows had the ability to kill Staphylococcus aureus. We report the production of cloned cows carrying human lysozyme gene knock-in β-casein locus using ZFNs. Our findings open a unique avenue for the creation of transgenic cows from genetic engineering by providing a viable tool for enhancing resistance to disease and improving the health and welfare of livestock.

Drivers of Post‐partum Uterine Disease in Dairy Cattle

Post-partum uterine disease has a detrimental effect on dairy cow fertility; affected cows require more serves per conception, have reduced conception rates and are more likely to be culled for infertility. Furthermore, the detrimental effects on fertility remain even after clinical resolution of disease. There are many factors that influence a cow's resistance to or development of post-partum disease, and the key drivers determining disease outcome are uterine microbial load, regulation of inflammation and immune responses peripherally and at a local level, production pressure, and metabolic (energy) status. These factors are intricately interlinked, which makes assessment of their individual effects difficult. It is clear, however, that the period surrounding calving is a key transition phase and events during this time point will influence uterine disease outcome and subsequent fertility. Good peripartum management and accurate diagnosis are critical to facilitate the use of the most effective treatment and limit the negative impact of post-partum uterine disease on fertility. If we can improve our understanding of the underlying causes of disease, then we can identify 'at risk' animals and implement management and breeding strategies to prevent uterine disease or reduce its severity. Thus, this article aims to summarize the key factors that drive uterine disease in the post-partum dairy cow.

Effect of Glucocorticoid-Induced Insulin Resistance on Follicle Development and Ovulation

Polycystic ovarian syndrome (PCOS) is characterized by hyperandrogenemia, polycystic ovaries, and menstrual disturbance and a clear association with insulin resistance. This research evaluated whether induction of insulin resistance, using dexamethasone (DEX), in a monovular animal model, the cow, could produce an ovarian phenotype similar to PCOS. In all of these experiments, DEX induced insulin resistance in cows as shown by increased glucose, insulin, and HOMA-IR (homeostasis model assessment of insulin resistance). Experiment 1: DEX induced anovulation (zero of five DEX vs. four of four control cows ovulated) and decreased circulating estradiol (E2). Experiment 2: Gonadotropin-releasing hormone (GnRH) was administered to determine pituitary and follicular responses during insulin resistance. GnRH induced a luteinizing hormone (LH) surge and ovulation in both DEX (seven of seven) and control (seven of seven) cows. Experiment 3: E2 was administered to determine hypothalamic responsiveness after induction of an E2 surge in DEX (eight of eight) and control (eight of eight) cows. An LH surge was induced in control (eight of eight) but not DEX (zero of eight) cows. All control (eight of eight) but only two of eight DEX cows ovulated within 60 h of E2 administration. Experiment 4: Short-term DEX was initiated 24 h after induced luteal regression to determine if DEX could acutely block ovulation before peak insulin resistance was induced, similar to progesterone (P4). All control (five of five), no P4-treated (zero of six), and 50% of DEX-treated (three of six) cows ovulated by 96 h after luteal regression. All anovular cows had reduced circulating E2. These data are consistent with DEX creating a lesion in hypothalamic positive feedback to E2 without altering pituitary responsiveness to GnRH or ovulatory responsiveness of follicles to LH. It remains to be determined if the considerable insulin resistance and the reduced follicular E2 production induced by DEX had any physiological importance in the induction of anovulation.

Insulin responses to acute glucose infusions in Busa and Holstein-Friesian cattle breed during the peripartum period: Comparative study

The aim of this study was to compare insulin responsevness to acute glucose infusion in cows of Holstein Friesian (HF) and Busa breeds during the peripartal period. Eight cows per each group (HF and Busa), were chosen. At day 7 prior to calving (ante partum) and day 14 after calving (post partum) animals were subjected to a glucose tolerance test (GTT). Blood samples were taken immediately before infusion and 15, 30, 60, 120 and 180 min thereafter. Glucose and insulin concentrations were measured in each blood sample, while BHBA and NEFA were measured only in samples taken before the infusion. QUICKY an indicator of insulin resistance in cows was calculated. Basal glycemia did not significantly differ between the breeds. Basal insulinemia was significantly higher in Busa than in HF cows in both examined periods (p<0.001, respectively). Basal NEFA levels tended (p=0.06) to be higher in Busa cows compared with those of HF ante partum, and was significantly higher (p<0.001) post partum. Basal BHBA was significantly lower in Busa than HF cows in both examined periods (p<0.01; p<0.001). QUICKI was significantly lower in Busa compared to HF cows both ante partum and post partum periods (p<0.001, respectively). Glycemia determined during GTT were higher in Busa than HF cows, both ante partum and post partum, but significantly starting from minute 15 ante partum i.e. minute 30 post partum. Insulinemia determined during GTT was significantly lower at min 15, and significantly higher starting from min 90 in Busa than HF cows, both ante partum and post partum. Results obtained in this study indicate on difference in insulin responsevness to acute glucose infusion between the examined breeds, which is probably a consequence of the difference in the degree of negative energy balance rather than of selection on high milk production. Namely, decreased insulin tissues sensitivity and decreased insulin responsiveness in Busa compared to HF cows is probably the consequence of inadequate energy intake from alimentary sources which leads to enhanced usage of energy from body reserves. [Projekat Ministarstva nauke Republike Srbije, br. 46002]