High environmental temperature and their impact on the zoohygiene parameters of farms, productivity and metabolic adaptation of cow

Biološka adaptacija krava na visoke ambijentalne temperature podrazumeva smanjenu proizvodnju mleka i porast temperature površine kože. THI indeks je značajan pokazatelj opterećenja krava toplotnim stresom. Prosečna maskismalna vrednost THI u periodu 2005-2016 pokazuje trend porasta u svim mesecima osim u januaru oktobru i novembru. Topla leta u Srbiji sa izuzetno visokim temperaturama, nastaju svake pete godine, kada su krave posebno pogođene. Ovakve promene dovode do globalnog zagrevanja i klimatskih promena koje utiču na biološku adaptaciju krava. Nisu postojale značajane razlike u vrednosti THI u funkciji regije u Vojvodini u kojoj je vršeno merenje THI, pa se Vojvodina može posmatrati kao jedinstvena celina u proceni toplotnog stresa krava. Sezona pokazuje uticaj na vrednosti ocena dobrobiti krava na farmama prema Welfare Quality® scoring sistemu. Odstupanja u vrednosti skorova za pojedine kriterijume ne dovode do značajnih promena u oceni ukupne dobrobiti krava na farmi i na klasifikaciju farme prema oceni dobrobiti. Potrebno je izvršiti dodatna istraživanja da bi se ispitao uticaj sezone na ocenu dobrobiti na farmama. Upotreba termovizijske kamere u proceni termalnog opterećenja krava na farmama bazira se na fiziološkim princiima termoregulcije kod goveda. površine tela krava bila je u rasponu od 34,1 do 38,5°C. Najviša temperature površine tela izmerena je u avgustu, a najniža  u zimskom periodu. Nađena je značajna pozitivna korelacija THI i temperature površine tela. Korelacione i regresione analize pokazuju da postoji značajna negativna linearna korelacija između THI i proizvodnje mleka, odnosno pozitivna korelacija između THI i temperature vimena kože i očne regije izmerene termovizijskom kamerom. Predikcija servis perioda je mnogo kvalitetnija ako se koristi kvadratna jednačina, jer dužina servis perioda nije zavisna od THI sve do momenta dok se ne pređe stresni prag za toplotni stres kada je korelacija THI i dužine servis perioda pozitivna. Pokazalo se da kvadratne jednačine daju bolju povezanost od linearnih, tako da je koncentracija amonijaka blago rasla kada je THI 40-60, a potom opadala u toplotnom stresu. Koncentracija H2S se ponašala drugačije u odnosu na amonijak, njena vrednost je bila najviša kod najviših i najnižih vrednosti THI. Dinamičke promene metabolita i index insulinske rezistencije značajno koreliraju sa količinom proizvedenog mleka kod krava izloženih toplotnom stresu. Varijacije u proizvodnji mleka tokom trajanja toplotnog stresa mnogo je bolje prevideti kada se THI index koristi zajedno sa vrednostima glukoze i TNF-α kao metaboličkih prediktora.  DatumAB  Biological adaptation of cows to high ambient temperatures implies reduced production of milk and increase of surface temperature of the skin. The THI index is a significant indication of the burden of cows with heat stress. The average masculine value of THI in the period 2005-2016 shows a trend of increase in all months, except in January of October and November. Extreme warm years in Serbia are created every five years, when cows are particularly affected. These data support the global warming and climatic changes that affect the biological adaptation of cows. There were no significant differences in the value of THI in the 8 function of the region in Vojvodina where the THI was measured, so that Vojvodina can be considered as a single entity in the assessment of the heat stress of cows. The season shows the impact on the value of the cow welfare on farms according to the Welfare Quality® scoring system. Deviations in the value of the scores for certain criteria do not lead to significant changes in the estimation of the total welfare of cows on the farm and on the classification of the farm according to the welfare assessment. Further research needs to be carried out to examine the impact of the season on the welfare assessment on farms. The use of a thermovision camera in the assessment of the thermal load of cows on farms is based on the physiological principles of thermoregulation in cattle. the surface of the cow's body ranged from 34.1 to 38.5 ° C. The highest surface temperature of the body was measured in August and the lowest in the winter period. Significant positive THI correlation and body surface temperature were found. Correlation and regression analysis show that there is a significant negative linear correlation between THI and milk production, that is, a positive correlation between THI and skin and skin temperature and eye region measured by a thermionic camera. The service period prediction is much better if a square equation is used since the length of the service period is not dependent on the THI until the heat stress stress threshold is exceeded when the THI correlation and the service period of the period are positive. When it comes to air quality, it has also been shown that square equations provide a better connection to linear ones, so the ammonia concentration is slightly increased when THI is 40-60, and then decreases in heat stress. The concentration of H2S behaved differently in relation to ammonia, its value being highest at the highest and lowest values of THI. Dynamic changes in the metabolite and index of insulin resistance significantly correlate with the amount of milk produced in cows exposed to heat stress. Variations in milk production during the duration of heat stress is much better overlooked when the THI index is used together wiith the glucose and TNF-α values as metabolic predictors.

Blood Serum Stability Limit and Maximum Storage Time of Bovine Samples

Background: Measuring metabolic parameters in the blood has been an indispensable tool for assessing the productive and health status of dairy cows for more than 100 years. The values of laboratory parameters depend on various preanalytical, analytical and postanalytical factors. The most important preanalytical factors are sample transport time and temperature, hemolysis, anticoagulant type, and sample volume.Preanalytical factors can lead to reduced stability of the analyte in the sample, which changes their concentration. Loss of stability changes the time of storage and manipulation of the sample, which determines the criteria for its acceptance or rejection. The two stability indicators are stability limit and maximum permissible instability. A stability limit (SL) is defined as the period of time in which a property variation does not exceed a maximum permissible instability (MPI). The aim of this study was to determine the SL and MPI for each analyte in the blood serum of cows and to determine whether SL differs in the function of the presence of preanalytical errors in the blood sample.Materials, Methods & Results: Three hundred samples of dairy cow origin in different periods of lactation participated in this research. They were classified into 6 groups of 50 samples: according to the time from sampling to processing in the laboratory (0-4 h, 4-8 h and over 8 h; all transported on dry ice, protected from environmental factors, without preanalytical errors) and according to the presence of preanalytical errors (group with hemolysis, a group transported at ambient temperature and a group with a small sample volume). Each sample was aliquoted in two portions. One portion was left at +4°C and tested once a day for 6 days of sample storage, and the second portion, placed at -20 °C, was tested once a month for 6 months. The MPI had a value ranging from 1.55 to 8.4. Metabolic profile analytes with lower MPI values (1.51-3.22) were albumin (ALB), total protein (TPROT), UREA, glucose (GLU), calcium (Ca), and phosphorus (P). Higher MPI values (5.1-8.3) were found for nonesterified fatty acids (NEFA), beta-hydroxybutirate (BHB), cholesterol (CHOL), triglycerides (TGC), total bilirubin (TBIL) and aspartat aminotransferase (AST). For most parameters, we can conclude that their PD% changed faster in storage conditions at +4 °C compared to the regime of -20 °C. The largest number of biochemical analytes in bovine blood serum shows preserved stability in the first 6 days at +4°C or 6 months at -20°C if transported to the laboratory within 8 h after sampling in ideal conditions and without the action of preanalytical errors. Prolonged transport under ideal conditions or the existence of preanalytical errors such as transport at room temperature, hemolysis or small sample volume shorten the stability of the ALB, NEFA, GLU, UREA and P. Concentration of all analytesdecreasesduring the stability test except for UREA, NEFA, BHB and for CHOL and TGC in some groups. Variations in parameters such as BHB, NEFA, TBIL, AST, and Ca have shown potential clinical significance. At storage conditions at +4°C, clinically significant variations at at least one measurement point were found for AST (7.5% of samples), BHB (6.1% of samples), NEFA (9.9% of samples) and for TBIL (in 7% of samples).Discussion: This study can help define acceptable delay times and storage conditions for bovine blood samples, which is of great importance because in working with farm animals it is often not possible to take samples in a short time and deliver them to the laboratory, and samples are often burdened with certain preanalytical errors with limited possibilities of re-sampling

Ketosis in Dairy Cows during Early Lactation - Detection in Pooled Blood Serum Samples

Background: Ketosis is the most important metabolic disease with prevalence from 15 to 45%. Ketosis is diagnosed using a metabolic profile. Due to the high prevalence, it is necessary to determine a large number of metabolic profiles within farm, which represents an additional cost, so the implementation of pooled serum in assessing the metabolic status of cows was examined. The aim of this study was to validate and evaluate the influence of the relative position (Z-score) of the value of pooled sample metabolic parameters within the known reference value of healthy cows in the detection of ketosis in herd during early lactation.Materials, Methods & Results: The experiment has been carried out using  blood samples collected by puncture of coccygeal vein from 50 ketotic and 50 healthy cows. Laboratory analysis includes determination of beta-hydroxybutyrate-BHB, non-esterified fatty acids-NEFA, cholesterol-CHOL, triglycerides-TGC, glucose-GLU, albumin-ALB, total protein-TPROT, UREA, Ca, P, total bilirubin-TBIL and aspartat aminotransferase-AST. The pooled serum was made from 10 individual samples originating from 10 different cows. A serum aliquot of 0.1 mL was taken from each sample, and a 1 mL volume of pooled serum was finally formed. Three types of serum pools were made: 1) 30 pooled sample were from ketosis; 2) 30 pooled sample were from healthy cows and 3) 60 pooled samples containing mixed sera of healthy cows and cows with ketosis were made as follows: 10 pools contain 10% to 60% of ketotic cows (1/10 to 6/10 samples). Statistical analysis includes: a) difference in metabolite concentration and Z-score in pooled sample and arithmetic mean individual sample in healthy and ketotic cow, b) correlation between Z-score of pooled sample and arithmetic mean of individual sample, c) ability of Z-score of metabolite to divide ketotic from healthy cow, d) correlation between Z-score and % of ketotic cow in pooled sample; and e) calculation of 95%CI of pooled sample Z-scores for each % of ketotic cow in pools. Z-score and all analysis were calculated for each metabolic parameter. The results of the study show that the mean values and Z-scores of the pool and the calculated average value of the individual samples participating in that pool differ significantly in healthy cows and cows in ketosis, except for TPROT and Ca. A higher value and a higher Z-score were found for BHB, NEFA, UREA, TBIL and AST, and a lower value and a lower Z-score for TGC, CHOL, GLU, ALB and P in ketotic cows compared to healthy cows. The value of the Z-score of the pooled sample and the calculated mean values of individual samples participating in the pool are highly correlated with each other (coefficient of determination over 99%). Z-score of metabolites in the pooled sample can be used to distinguish healthy from ketotic cows (ROC AUC= 0.711 to 0.989), except for TPROT and Ca. The Z-score value of the pooled sample shows a linear correlation with the percentage of ketotic cows in the pool and the reference ranges of Z-scores change significantly as a function of the percentage of ketosis cows.Discussion: Modern research on the metabolic profile in cows requires obtaining a large amount of information from as few samples as possible. The advantages of using the Z-score are reflected in the following: this score does not depend on the absolute value of the metabolite, but on the position within the known population reference value, Z-score of sample and the arithmetic mean of individual samples included in the same pool are almost identical, the Z-score of these 2 groups of results is ideally correlated, the Z-score significantly correlates with the % of ketosis samples in the pooled sample. The use of pooled sample Z-score can be a useful in a herd level assessment of metabolic status and detection of ketosis as most important metabolic disease in dairy cows.Keywords: dairy cattle, ketosis, metabolic disease, metabolic profile, pooled serum, z-score, diagnostics

Thermal comfort of cows and temperature humidity index in period of 2005-2016 in Vojvodina region (Serbia)

The aim of this study is to determine value of temperature-humidity index (THI) in period of 2005-2016. in Vojvodina and their correlations with milk production and temperature of body surface of animals. THI index is calculated according to the following formula THI=(1,8×Temperature)-(1-Relative Humidity) × (Temperature- 14,3)+32. Temperature and humidity data were collected directly from Hydrometeorological Institute of Serbia. Average THI values were calculated for every month for every year from 2005 to 2016. Measuring spots were cities Vršac, Zrenjanin, Kikinda, Palić, Sombor, Rimski Šančevi and Sremska Mitrovica. Temperature and humidity are noted at 14h, so they represented maximal average values of THI index. Trend of THI values was represented for each day in every month in years from 2005. to 2016. Average production of drinking milk for year of 2016 was calculated. This year was chosen because is the last year of research and represents cumulative effect of heat stress in cows. Data were collected from Statistic Institute of R. Serbia. Thermo-vision camera was used for determining skin temperature of udder and skin in eye region. Results were showed that temperature ranged from 40.3 in January to 77.5 in July. Average maximal THI value in period of 2005-2016 showed that heat stress was presented in May, June, July and August. Drinking milk production was the greatest in January. After that it started dropping. The lowest production of drinking milk was noted in August with an increase afterwards till December. Body surface temperature was ranged from 34.1 to 38.5ºC. The highest body temperature was measured at August and the lowest in winter time. Significant negative correlation between ten-year average THI value and milk production was noted. Positive correlation was noted between THI and body temperature. From 2005 to 2016 positive linear trend of THI values that were measured in hottest period of day was noted. In every month statistically significant linear trend of rising THI value was founded, except in January, October and November. Extremely hot summers in Serbia appear in every five years when cows are affected the most. Showed data indicated global warming and climate changes which affect biological adaptation of cows

Relationship between milk production and metabolic adaptation in dairy cows during heat stress

The aim of this study is to determine correlation between change in milk production and metabolic adaptation of cows during heat-stress. Experiment included 30 Holstein-Frisian cows. Cows exposed to heat-stress, which is expressed in high THI index, have lower milk production, higher concentration of insulin and lover concentrations of glucose and NEFA. Indexes of insulin resistance-RQUICKI, insulin: glucose and insulin: NEFA relations are higher in cows under heat stress. Grouping cows in accordance to reduced milk yield have showed that trend of reduction of glucose and NEFA levels, followed by increased insulin level, higher RQUICKI, greater insulin: glucose and insulin: NEFA ratios, started and increased during the reduction in milk production. Among this, significant correlation was founded between these parameters and milk yield. Significant correlation was also noted between those parameters. Change in metabolic value is of great importance for prediction of cows that would have decreased milk yield (above 18%). With almost 90% certainty cows with great reduction in milk yield can be detected. These cows have had following relative changes in values of metabolic parameters during heat-stress compared to thermo-neutral period: insulin increased for ≥12.5%, reduction in NEFA values for ≤14.1%, reduction in glucose for 21.5%, RQUICKI index increased for ≥9.6%, insulin: NEFA ratio increased for ≥20.1% and insulin: glucose for ≥20.3%. Dynamical changes in metabolites and insulin resistance values have great influence on milk yield in cows under heat stress. Decreasing in glucoses followed by increased insulin level and increased insulin sensitivity indicate that glucose is transferred from udder to other tissues which can cause decreased milk production

Heat stress of dairy cows in Serbia: Review

The climatic conditions in Serbia are suitable for the development of heat stress in cows. The values of the bioclimatic THI indicator point to a positive trend in increase in the number of days during which the conditions for the occurrence of heat stress are present. In cows, a change in body temperature is noted, activation of the cooling mechanisms, along with reduced milk production and reproductive efficiency. The behavioral changes of cows occur on farms, and the level of welfare decreases slightly when measured according to animal�based criteria. Changes in productivity are mainly related to metabolic, hematological and inflammatory adaptations. The metabolic adaptation that leads to a decrease in milk production is related to an increase in sensitivity to insulin with reduced lipolysis, an increase in TNF-α in cows, as well as to metabolic rearrangements of the mammary gland. Reproductive efficiency is reduced and is characterized by reduced expression of estrus and reduced response to estrus induction procedures. High ambient temperatures, in in vitro conditions, can affect the stability of laboratory parameters in the blood serum of cows. Cows exhibit different profiles of resilience to heat stress, and the study of resilience curves, for productive and blood parameters, represents the starting point for selecting cows that will tolerate heat stress better. For this purpose, the cumulative effects of heat stress expressed in the area under the resilience curve can be used. Certain precautionary measures such as providing shade, cooling by using fans and sprinklers or some other advanced technological methods, can reduce losses during heat stress. All of the above indicate that it is necessary to pay extra attention to all aspects of health care and production on cow farms in Serbia during late spring and summer when the animals are exposed to heat stress. Keywords: temperature-humidity index, milk production, reproduction, prevention, resilience, metabolis

Lipolysis and ketogenesis in cows in early lactation (review)

Peripartal metabolic stress is characterized by increased lipid mobilization, when non-esterified fatty acids (NEFA) are increased, as well as by increased ketogenesis, when the concentration of beta-hydroxybutyrate (BHB) is increased. NEFA are metabolized in all tissues but the main organ is the liver. Possible processes are: a) complete oxidation of NEFA, b) partial oxidation and synthesis of ketone bodies (BHB), c) development of triglycerides from NEFA that can be transported or stay in the liver when fatty liver is apparent. Moreover, increased lipolysis and ketogenesis can cause oxidative stress because concentrations of MDA and/or TBARS are positively correlated with NEFA and BHB concentrations. The increase in NEFA during the peripartal period affects the cellular immunologic response by changing intracellular signals, gene expressing control, activation of transcriptional factors, apoptosis induction and by modifying mediators of lipid production. Increased proportion of cows with high NEFA and BHB concentrations in the herd can cause reduced milk yield at the end of a standard 305-day lactation. NEFA concentrations can be related to postpartal ovarian activity, especially given that blood NEFA concentrations represent NEFA concentrations in the ovarian follicular fluid. Cows on farms with lower scores of animal welfare and nutrition have higher concentrations of cortisol, NEFA, BHB, bilirubin, glucose and urea. NEFA and BHB concentrations in early lactation can be used for estimating metabolic adaptation in the first 8 weeks after calving. For the estimation of metabolic adaptation, increased lipolysis has a greater significance than decreased anabolic parameters

Multiparametric analysis of blood parameters and hyperketonemia in cows

The aim of this study is to examine the interrelationships and importance of biochemical and endocrine blood parameters in the assessment of beta-hydroxybutyrate (BHB) values in healthy and ketotic cows using multiparameter statistics. The experiment included 45 Holstein Friesian cows (22 healthy and 23 with ketosis). The criterion used for detecting ketosis was the value of BHB ˃1.2 mmol/L. Based on laboratory indicators, cows were precisely classified into two large clusters: a cluster of healthy cows and a cluster of cows suffering from ketosis with minimal mixing of individual cows between clusters. Metabolic parameters were divided into two large clusters: parameters whose values increased in ketosis and decreased in healthy animals and parameters whose values decreased in ketosis and increased in healthy individuals. In ketotic cows there was a higher expression of nonesterified fatty acids, total bilirubin, aspartate aminotransferase, insulin and growth hormone, and a lower expression of glucose, albumin, triglycerides, cholesterol and total lipids compared to the healthy group. In 3 cows with ketosis, greater metabolic similarity with healthy cows was found, because of the absence of pronounced changes in the concentration of hormones and glucose. Thyroxine and triiodothyronine showed either increased or decreased expression in ketotic cows. In cows with lower values of these hormones, there were more pronounced metabolic changes characteristic of ketosis. For the development of metabolic adaptations to ketosis, in addition to hyperketonemia, there must be endocrine changes and changes in glycemia.Publishe

Changes in Hematological and Biochemical Parameters of Canine Blood During Long-term Use of Ivermectin for the Treatment of Heartworm Disease

Ivermektin je antiparazitski lek koji pripada familiji makrocikličnih laktona. Veoma je efikasan protiv endo- i ekto- parazita u niskim dozama, a u poslednje vreme se najčešće upotrebljava u prevenciji i lečenju bolesti srčanog crva. Cilj ovog istraživanja je bio utvrditi da li se prilikom dugotrajne primene ivermektina, u dozama od 10 μg/kg t.m., u lečenju pasa od srčanog crva javljaju promene u hematološkim i biohemijskim parametrima koje se mogu pripisati dejstvu leka. Studija je obuhvatala pse koji su primali ivermektin parenteralno na svake dve nedelje tokom šest meseci u terapiji srčanog crva. Krv je uzorkovana u momentu dijagnostikovanja bolesti kod psa, pre početka terapije, a zatim prilikom kontrolnog testiranja nakon završenih šest meseci terapije. Aplikacija ivermektina dva puta mesečno u dozi od 10 μg/kg t.m. u trajanju od šest meseci u cilju lečenja bolesti srčanog crva kod pasa dovodi do značajnog variranja pojedinih parametara posle terapije u odnosu na pre početka terapije. U hematološkom profilu ukupan broj limfocita i RDW pokazuju najveću varijabilnost koja se može pripisati dejstvu leka (53,33%). Zatim slede monociti (46,66%), hematokrit (40%), eritrociti i hemoglobin (33,33%), MCH i trombociti (26,66%) i na kraju leukociti, MCHC i neutrofili (13,33%). U biohemijskom profilu, variranje koje se može pripisati leku se javilo kod 60% pasa za parametre kreatinin, AST, trigliceridi i kalcijum, 46,66% za fosfor, 40% za ALT, 33,33% za ureu, 26,66% za ukupne proteine, 20% za albumine i 13,33% za glukozu, bilirubin, ALP i holesterol. Dobijeni rezultati ukazuju da je potrebno kontrolisati životinje prilikom dugotrajne primene ivermektina, obavestiti vlasnike o efektima leka tokom dugotrajne primene, a takođe treba razmotriti i upotrebu suplemenata koji ublažavaju neželjene efekte leka.Ivermectin is an antiparasitic medicine that belongs to the macrocyclic lactone family. It is highly effective against endo- and ecto- parasites at low doses, and lately it is most widely used in the treatment and prophylaxis of canine heartworm disease. The aim of this study was to determine whether there is the occurrence of changes in hematological and biochemical blood parameters due to the long-term application of ivermectin, at doses of 10 μg/kg b.w., in heartworm disease treatment, that can be attributed to the effect of the medicine. This study was conducted on dogs with heartworm disease that received ivermectin twice a month for six months. Blood was collected at the moment of diagnosis, before treatment and after six months of therapy. The results showed that application of ivermectin twice a month, at doses of 10 μg/kg b.w., during a six-month period of heartworm treatment, induced significant variability of the certain parameters after the treatment in regard to before the treatment. The greatest variability in hematological findings that can be attributed to the effects of medicine was shown by total lymphocyte count and RDW (53.33%), monocyte count (46.66%), hematocrit (40%), total red blood cells count and hemoglobin (33.33%), MCH and platelets (26.66%), total white blood cells count, MCHC and neutrophils (13.33%), respectively. The variation that can be associated with the effects of ivermectin in biochemical parameters was demonstrated in 60% of the dogs for the parameters creatinine, AST, triglycerides and calcium, 46.66% phosphorus, 40% ALT, 33.33% urea, 26.66% total protein, 20% albumin, 13.33% glucose, bilirubin, ALP and cholesterol, respectively. These results point out that better control of animals should be provided during long-term use of ivermectin, also that the owners should be thoroughly informed about the effects of the medicine and that some consideration should be given to the use of supplements which could ease the side effects of ivermectin

Blood Serum Stability Limit and Maximum Storage Time of Bovine Samples

Background: Measuring metabolic parameters in the blood has been an indispensable tool for assessing the productive and health status of dairy cows for more than 100 years. The values of laboratory parameters depend on various preanalytical, analytical and postanalytical factors. The most important preanalytical factors are sample transport time and temperature, hemolysis, anticoagulant type, and sample volume. Preanalytical factors can lead to reduced stability of the analyte in the sample, which changes their concentration. Loss of stability changes the time of storage and manipulation of the sample, which determines the criteria for its acceptance or rejection. The two stability indicators are stability limit and maximum permissible instability. A stability limit (SL) is defined as the period of time in which a property variation does not exceed a maximum permissible instability (MPI). The aim of this study was to determine the SL and MPI for each analyte in the blood serum of cows and to determine whether SL differs in the function of the presence of preanalytical errors in the blood sample. Materials, Methods & Results: Three hundred samples of dairy cow origin in different periods of lactation participated in this research. They were classified into 6 groups of 50 samples: according to the time from sampling to processing in the laboratory (0-4 h, 4-8 h and over 8 h; all transported on dry ice, protected from environmental factors, without preanalytical errors) and according to the presence of preanalytical errors (group with hemolysis, a group transported at ambient temperature and a group with a small sample volume). Each sample was aliquoted in two portions. One portion was left at +4°C and tested once a day for 6 days of sample storage, and the second portion, placed at -20°C, was tested once a month for 6 months. The MPI had a value ranging from 1.51 to 8.4. Metabolic profile analytes with lower MPI values (1.51-3.22) were albumin (ALB), total protein (TPROT), UREA, glucose (GLU), calcium (Ca), and phosphorus (P). Higher MPI values (5.1-8.4) were found for nonesterified fatty acids (NEFA), beta-hydroxybutirate (BHB), cholesterol (CHOL), triglycerides (TGC), total bilirubin (TBIL) and aspartat aminotransferase (AST). For most parameters, we can conclude that their PD% changed faster in storage conditions at +4°C compared to the regime of -20°C. The largest number of biochemical analytes in bovine blood serum shows preserved stability in the first 6 days at +4°C or 6 months at -20°C if transported to the laboratory within 8 h after sampling in ideal conditions and without the action of preanalytical errors. Prolonged transport under ideal conditions or the existence of preanalytical errors such as transport at room temperature, hemolysis or small sample volume shorten the stability of the ALB, NEFA, GLU, UREA and P. Concentration of all analytes decreases during the stability test except for UREA, NEFA, BHB and for CHOL and TGC in some groups. Variations in parameters such as BHB, NEFA, TBIL, AST, and Ca have shown potential clinical significance. At storage conditions at +4°C, clinically significant variations at at least one measurement point were found for AST (7.5% of samples), BHB (6.1% of samples), NEFA (9.9% of samples) and for TBIL (in 7% of samples). Discussion: This study can help define acceptable delay times and storage conditions for bovine blood samples, which is of great importance because in working with farm animals it is often not possible to take samples in a short time and deliver them to the laboratory, and samples are often burdened with certain preanalytical errors with limited possibilities of re-sampling