Research on the impact of heat stress on animals has mainly been related to cattle, while sheep have been neglected and the impact of heat stress on sheep production is still insufficiently researched. There are numerous stressors related to the procedures and methods of breeding sheep in barns and pastures among them ambient temperature is the most important variable because its effect is exacerbated in the presence of high humidity. Thermal indices are useful for assessing the influence of weather parameters in a certain agroecological area, of which the temperature-humidity index proved to be the best thermal index for assessing the harmful effect of heat stress on the productive performance of animals. Sheep have good adaptability and they are resistant to harsh environmental conditions, still in addition to a certain tolerance to heat stress, high temperatures can negatively affect sheep, which most often leads to dehydration, reduced appetite, reduced milk production and increased risk of disease. Mechanisms that help sheep to survive the challenge of heat stress include morphological, behavioural, physiological, blood biochemistry and genetic bases of adaptation. Sheep can combat heat stress by seeking shade, drinking enough water, and properly ventilating the barn. Increasing the productivity of sheep by adapting various management strategies including housing and animal management and climate monitoring may enhance production capacity of the herd. Therefore, heat stress has a negative effect on sheep, temperatures will increase year by year, and therefore it is necessary to investigate the relationship between sheep production and heat stress in time, to improve sheep farming and make life easier in the days ahead.

The aim of the present study was to determine a correlation between blood concentration of lipids and the content of lipids in the liver of dairy cows in the transitional period. The Holstein dairy cows (n = 40) were divided into four groups: the first group (A) included late pregnant cows (n = 10) from the 10th to 4th day before calving; the second group (B) included late pregnant cows (n = 10) from the 4th to 1st day before calving; the third group (C) included clinically puerperal healthy cows (n = 10), whereas the fourth group (D) included puerperal ketotic cows (n = 10). The liver and blood samples were taken from all the cows. Pathohistological examination of liver samples showed statistically significantly higher (p < 0.01) lipid infiltration in ketotic cows compared to healthy cows in late pregnancy and puerperium. Biochemical examination of blood serum showed significantly higher values (p < 0.01) of nonesterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB) in ketotic cows, such as lower blood concentrations of glucose (p < 0.01), triacylglycerols (TG) (p < 0.01), and total cholesterol TChol. (p > 0.05) compared to the values obtained in the blood serum in the groups of healthy cows before and after calving. The significantly positive correlations were determined between the content of lipids in the liver and blood concentration of NEFA (r = 0.67; p < 0.05) and BHB (r = 0.55; p < 0.05) as well as the negative ones between the content of lipids in the liver and blood concentrations of glucose (r = -0.45; p < 0.05), TG (r = -0.55; p < 0.05) and TChlol. (r = - 0.39; p < 0.05). Our investigations suggested that changes in the blood concentrations of NEFA, BHB, TG, TChol. and glucose served as major biochemical indicators in determining ketosis and liver steatosis in the dairy cows in the transitional period.

Hemolysis is a common cause of errors in laboratory tests as it affects blood parameters and leads to a positive or negative bias. This study aims to examine the relationship between the level of hemolysis (expressed as cell-free hemoglobin concentration, g/L) and the variability of metabolic and endocrine parameters and to determine the threshold level of hemolysis that causes an analytically and clinically significant bias for the twenty most frequently examined blood parameters in cows. Paired blood samples of 10 mL each were obtained from 30 cows. One was subjected to mechanical trauma and plasma was extracted directly from the other. Hemolyzed and non-hemolyzed samples from the same animal were mixed to obtain final samples with cell-free hemoglobin concentrations of 0, 1, 2, 4, 6, 8, and 10 g/L. Metabolic and endocrine parameters were measured in the samples and their deviation and the linear equation between the level of hemolysis and the deviation were determined. The following threshold values of hemolysis were determined, which correspond to the acceptable analytical (lower value) and clinical (upper value) levels of parameter variability: BHB 0.96 and 4.81; NEFA 0.39 and 3.31; GLU 0.38 and 3.90; ALB 1.12 and 6.11; TPROT 1.40 and 6.80; UREA 6.62 and 20.1; TBIL 0.75 and 5.65; AST 0.11 and 2.18; GGT 1.71 and 8.90, LDH 0.01 and 0.11, ALP 0.97 and 2.95; TGC 1.56 and 15.5; CHOL 1.29 and 8.56; Ca 5.68 and 25.7; P 0.57 and 8.43; Mg 1.10 and 8.47; INS 1.15 and 3.89; T3 8.19 and 15.6; T4 8.97 and 18.5; and CORT 2.78 and 11.22 g/L cell-free hemoglobin. Three decision levels are available for each metabolic and endocrine parameter: if hemolysis is below the lower (analytical) threshold value, results can be reported without restriction; if hemolysis is between the lower and upper thresholds, the results can be issued with guidance in the form of corrective linear equations; and if hemolysis is above the upper (clinical) threshold, the results and sample must be discarded. This method contributes to an optimal approach to hemolysis interference with metabolic profile parameters in blood samples from cows.

Ketosis is a significant metabolic disorder in cows that occurs as a result of a negative energy balance, when the concentration of ketone bodies in the blood, milk and urine increases. Cow ketosis is a metabolic disease characterized by a disturbance in carbohydrate and fat metabolism with increased production of ketone bodies in the body. Basic metabolic adaptations in cows in ketosis are: increased concentration of BHB, increased concentration of NEFA, lower concentration of glucose, increased value of liver enzymes and bilirubin, disorder of macro and micro elements, increased values of inflammatory markers, oxidative stress, insulin resistance, and are accompanied by various associated diseases and behavioral disorders. Given that ketosis often occurs in different forms, and that the obtained values of the metabolic profile for most parameters remain within the reference values, it is necessary to examine the variability of blood parameters in order to recommend a new way of interpreting the metabolic profile in the assessment of ketosis in cows. We expect to determine which parameters show the greatest degree of variability, which will allow us to make a practical contribution to the diagnosis of ketosis, because we will determine the parameters that are most sensitive to ketosis, and whose variability in combination with specific changes in the BHB value allow not only the diagnosis of ketosis, but also the graduation its weight in each cow separately. The everyday practical way of assessing the health of animals is reflected in the comparison of the obtained values with the reference values, therefore it was necessary to determine in what percentage there is a large deviation of the parameter values (Z score above or below 2), which in a practical sense means that there has been a change obtained values outside the reference ones. When BHB is excluded, whose high deviation is the basis of the definition of ketosis, and the values of other metabolic parameters are observed, we conclude that in 360 measurements there are 105 deviations from the reference values, which is 29.17%, while in 70.83% of the measurements, the values of metabolic parameters are were within the reference values. The above results indicate that in practice a new way of reading and interpreting the results must be approached, which must take into account the position of the metabolic parameter value within the reference value, and not just the fact whether the metabolic parameter is outside the reference values.

Increasing milking frequency can increase milk production in cows by 15-20%, and increased milking frequency can affect different mechanisms of secretion and metabolic activity of the udder. In practice, cows are best milked twice a day with an average interval between two milkings of 12 hours, and in practice it is the most common range of 8-16 hours. It was shown that a 12-hour interval between two milkings was good for high-yielding cows, with a steady increase in milk production during the first half of lactation. An extended interval between two milkings will lead to inhibition of lactation with a consequent decrease in the amount of milk produced. Increasing the milking frequency of dairy cattle to more than two milkings per day results in an increase in milk production. Milking three times a day leads to an increase in milk production of 3 to 39% compared to milking twice. One of the most obvious effects as a result of increased milking frequency is the mobilization of body reserves. The primary mechanism leading to this is lipolysis. As a result of lipolysis, there is an increase in the concentration of NEFA and BHB in the blood plasma or serum with a decrease in the assessed body condition of the cows, and the mentioned changes are considered a typical response to an increase in milking frequency. The tests showed a significant decrease in the body condition score in cows that were milked six times compared to cows that were milked three times. Increased lipolysis and ketogenesis lead to a metabolic response and adaptation of cows, and these changes can sometimes lead to an increase in metabolic diseases in cow herds.

Pooled blood samples are an economical and high-quality way to show the state of a certain population, as well as the response of the population to certain factors of the external and internal environment, the use of pooled blood samples in veterinary medicine and related fields has found wide application, whether it is for the diagnosis of infectious diseases , the use of samples in internal quality control in the laboratory or in the diagnosis of various diseases. Creating a pooled blood sample saves time and reduces the cost of analysis, and enables easier storage of the sample, while individual samples require greater space, time and financial resources, with a greater source of errors. In the analytical sense, a larger volume of the collective sample (made up of a small volume of a larger number of samples) of blood enables a better determination of the detection limit, while in the case of individual samples, a sufficiently large amount of that one sample must be provided. Statistically estimable also differs, so with a pooled blood sample we can estimate the mean, but not the variability as in a population of individual samples. As a general rule, the mean value of the collected samples should be close to the middle of the reference range to be considered normal. The criteria for the interpretation of mean values have not been fully defined. It is considered that the mean value obtained should be in the range of 1 or 1.3 standard deviations in the reference population in order to be able to conclude that there are no individuals with significant metabolic problems. It was found that if there are up to 10% of abnormal metabolic values in the population, we will have a small deviation of the pool value from the population mean, which will amount to about 0.26 standard deviations, but that it largely depends on the analyte being measured. Our results showed that the average value of individual blood samples and the concentration obtained by pooling those individual samples give almost identical values that change identically as a function of the lactation period and the health of the cows. Due to all of the above, the preparation of pooled samples can be an interesting tool in the evaluation of the metabolic profile of larger cow populations.

Background: Iron (Fe) is microelement, essential to ensure some metabolic physiological process. Although Fe is a stable element in the body that is tightly regulated, metabolic stress, lipolysis, ketogenesis, endocrine change, insulin resistance and inflammation in early lactation can influence Fe status in blood. The objectives of this experiment were to determine the Fe status of cows in early lactation and determine whether measures of Fe status were in relation with hematological, metabolic, endocrine and inflammatory response in cows during early lactation. Materials, Methods and Results: The experiment included 30 healthy cows in the 1(st) 6 weeks of lactation. Laboratory analysis includes determination of Fe status (blood Fe, unsaturated iron-binding capacity (UIBC), total iron-binding capacity (TIBC), transferrin saturation percentage (TS%) and metabolic response of cows (complete blood count, non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), cholesterol, triglycerides, glucose, total bilirubin (TBIL), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), cortisol, T3, T4, insulin, RQUICKIBHB, TNF-alpha, and haptoglobin). Blood samples were collected by puncture of coccygeal vein. Fe increased from the 1st to the 6th week of lactation, with significantly lower concentrations in the 1(st) 2 weeks of the experiment (P < 0.01). TIBC and UIBC were lower in 1(st) 2 or 3 weeks of experiment (P < 0.01), while the TS% was unchanged. Hematological response included a significant lower MCV and HCT (P < 0.01) and tendency to decrease HGB and RBC (P < 0.1) in 1(st) 3 weeks of lactation compared to 2(nd) 3 weeks. WBC and PLT was unchanged, but NLR was higher in 1st 3 weeks of lactation (P < 0.05). Metabolic response was characterized by higher concentration of NEFA, BHB, TBIL, AST, GGT (P < 0.01) and NEFA:CHOL ratio (P < 0.05), and lower concentration of GLU, TGC, CHOL (P < 0.01) and ALB (P < 0.05) in 1(st) 2 or 3 weeks of lactation compared to period from 4 to 6 week. Endocrine response included lower concentration of insulin (P < 0.01), T3 and T4 (P < 0.1), and higher concentration of cortisol and RQUICKIBHB index of insulin resistance (P < 0.01) in 1(st) 2 or 3 weeks of experiment compared to period from 4 to 6 weeks. Inflammatory response included higher concentration of TNF-alpha and haptoglobin (P < 0.01) in 1(st) 2 or 3 weeks of experiment compared to period from 4 to 6 weeks. Fe concentration showed significant positive correlation with TIBC, UIBC, HGB, MCV, GLU, T3, T4 and INS and negative correlation with NLR, NEFA, BHB and RQUICKIBHB. TIBC and UIBC showed negative correlation with TBIL, AST, GGT, and NEFA:CHOL ratio and positive with ALB and TGC. Fe showed negative correlation with TNF-alpha, while TIBC and UIBC showed negative correlation with haptoglobin. Metabolic and inflammatory parameters had higher magnitude of change when Fe was extrapolated on deficit level (9 mu mol/L), compared to TIBC, UIBC, TS% and red blood cell parameters as functional indicators of Fe status. Discussion: Fe, TIBC and UIBC showed significant change in 1(st) 6 weeks of lactation. Decrease in Fe in cows could be related to general homeorhetic adaptation to the onset of lactation, since Fe correlates with indicators of lipolysis, ketogenesis, and endocrine parameters. The lower TIBC and UIBC observed in cows in 1(st) 3 weeks when Fe was lower is an unexpected finding, since Fe decrease usually increases TIBC and UIBC. TIBC correlates with hepatocytes indices of the functional status and lipid infiltration, so it is possible that TIBC decreases because of changes in lipid metabolism and acute response in the liver. Blood Fe, TIBC and UIBC can be useful indicators for assessing metabolic stress in early lactating cows.

The objective of this study was to describe the complex etiopathogenesis, forms, prevention and treatment of lameness in dairy cows. Since inflammation of the hoof mostly affects cows that have superior milk performance, it poses major health and economic issues. Laminitis can take different forms and courses, classified as acute and chronic, deep and superficial, aseptic and septic. Aseptic subdermatitis is of much greater concern, as it is a metabolic disease of the hoof corium with degenerative changes in the corium and horn. Its common causes are stress associated with calving, imbalanced diet, incidence of acidosis or alkalosis, high milk production, and overloading of the hooves. This results in the production of toxins, particularly histamine, in the forestomachs, leading to vasoconstriction, followed by vasodilation within the hoof corium and, consequently, oedema, hyperaemia, the destruction of blood vessels in the corium, and, at a later stage, degenerative changes in the corium and horn. Lameness develops, depending on the degree of pathological changes. Therefore, the prevention, early diagnosis and treatment of aseptic and septic laminitis are of major importance in managing the health and welfare of high-producing dairy cows.

Previous experimental models on cows have examined the difference in the metabolic adaptation in cows after niacin administration, without identifying the most important mediators between niacin administration and its biological effects, namely active forms of niacin. All tissues in the body convert absorbed niacin into its main metabolically active form, the coenzyme nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The aim of this study was to determine the influence of niacin administration in periparturient period on NAD, NADP and the NAD:NADP ratio and to determine relationship between these indicators of an active form of niacin with metabolic parameters in cow blood. The study included 90 healthy cows: 45 cows receiving niacin and 45 cows were negative control. The niacin group was treated with nicotinic acid for two weeks before, as well as two weeks after parturition. Nicotinic acid was applied per os with feed. In cows receiving niacin, there was a significantly higher concentration of NAD and NADP, but the NAD:NADP ratio did not differ compared with control. All three indicators were able to separate cows who received and who did not receive additional niacin. NAD and NADP are good indicators of the availability of niacin from additional sources. The NAD:NADP ratio is a good indicator of the biological effect of applied niacin on metabolites in cows due to its correlation with a number of metabolites: positive correlation with glucose, insulin, glucose to insulin ratio and the revised quantitative insulin sensitivity check index (RQUICKIBHB) of insulin resistance, triglycerides and cholesterol, and a negative correlation with nonesterified fatty acid (NEFA), beta hydroxybutyrate (BHB), gamma-glutamyltranspherase (GGT) and urea in cows receiving niacin. The same amount of added niacin in feed can produce different concentrations of NAD, NADP and NAD:NADP in the blood, and this was not related to their concentration before the addition of niacin. The change in the concentration of the active form of niacin (NAD, NADP and NAD:NADP) further correlates with the concentration of metabolic parameters, which indicates that the intensity of the biological effect of additional niacin can be accurately determined only if we know the concentrations of its active forms in blood. Under basal conditions (without additional niacin), active forms of niacin that already exist in the blood do not show significant correlations with metabolic parameters.

Metabolic stress in early lactation cows is characterized by lipolysis, ketogenesis, insulin resistance and inflammation because of negative energy balance and increased use of lipids for energy needs. In this study the relationship between lipid metabolite, lipid-based insulin resistance, and hepatocyte functionality indexes and tumor necrosis factor alpha (TNF-α) with extracellular heat shock protein 70 (eHsp70) was investigated. The experiment included 50 cows and all parameters were measured in blood serum. In cows with a more pronounced negative energy balance, the following was determined: a higher concentration of eHsp70, TNF-α, non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHB), NEFA to insulin and NEFA to cholesterol ratio and lower concentration of cholesterol, very low-density lipoproteins (VLDL), low density lipoproteins (LDL) and liver functionality index (LFI). The eHsp70 correlated negatively with the values of cholesterol, VLDL, LDL, and triglycerides, while correlated positively with the level of NEFA and BHB. A higher concentration of eHsp70 suggests the development of fatty liver (due to a higher NEFA to cholesterol ratio and lower LFI) and insulin resistance (due to a lower revised quantitative insulin sensitivity check index RQUICKI-BHB and higher NEFA to insulin ratio). The eHsp70 correlated positively with TNF-α. Both TNF-α and eHsp70 correlated similarly to lipid metabolites. In cows with high eHsp70 and TNF-α values we found higher concentrations of NEFA, BHB, NEFA to insulin and NEFA to cholesterol ratio and a lower concentration of triglycerides and VLDL cholesterol compared to cows that had only high TNF-α values. Based on the positive correlation between eHsp70 and TNF-α, their similar relations, and the additional effect of eHsp70 (high TNF-α + eHsp70 values) on lipid metabolites we conclude that eHsp70 has pro-inflammatory effects implicating lipolysis, fatty liver, and fat tissue insulin resistance.

The main goal of this research is to examine the influences of extensive breeding methods and their interactions on the result of rearing lambs of Sjenica pramenka breed, more precisely the influence of body weight values of lambs reared in four different locations: Novi Pazar, Raska, Tutin, Sjenica. Lambs were tested from January 2018 to April 2020. The average birth weight of Sjenica pramenka lambs for 2018 is 2.98 kg, for 2019 it is 3.03 kg, The average birth weight of Sjenica pramenka lambs for 2020 is 3.32 kg. The highest average birth weight of lambs was measured in Sjenica and amounted to 3.55 kg, and the lowest in Tutin with 2.59 kg. In Novi Pazar 3.36 kg, and in Raska 3.41 kg. The difference in birth weight between lambs can be explained by breeding conditions, sheep selection and nutrition.

Milk production in dairy cows has increased significantly in the last few decades and continues to increase. The beginning of lactation requires extremely great effort from cows to overcome metabolic stress, so the frequency of cows' illness is the most intense in this period. Significant variations in the adaptive responses to lack of energy and nutrients in this period occur in the body of cows, with numerous endocrine, hematological, immunological and other changes. Therefore, cows should be provided with adequate nutrients for a balanced meal, both in the period of drought and in all phases of lactation.

Overall sheep production is influenced by certain factors, genetic and paragenetic. Fertility traits of sheep are more influenced by non-genetic systematic factors, whether they are discontinuous in nature (year of birth, season of birth and lambing, partus in order, type of birth, sex of lambs) or continuous (age at first insemination, etc.). The research included 180 sheep of the Pramenka breed, Sjenica pramenka in the breeding areas of three municipalities: Priboj, Prijepolje and Nova Varos. Data on the growth of lambs in the lactation period were analyzed, as follows: weight at birth, weight at the age of 30 and 90 days of age. The influence of fixed paragenetic factors such as: breeding area, year of birth of ewes, lambing in order, type of lambing, sex on the manifestation and variability of the observed characteristics of lamb growth in the lactation period was observed. The breeding area and type of birth had a significant effect (P <0.01) on the weight of lambs from all three age categories. The year of birth of lambs and the interaction of the breeding area and type of birth had a highly significant effect (P <0.01) on the mass of lambs at birth and at the age of 90 days, and significantly (P <0.05) on the mass of lambs at 30 days of age. Lambs in a row and a half of lambs did not significantly affect any trait of lamb growth in the lactation period. The coefficients of determination for the observed traits were high and very significant and ranged from 0.775 (77.5%) in the mass of lambs at birth to 0.397 (39.7%) in the mass at 30 days.

Vitamin niacin is of great importance for energy metabolism. Physiological niacin is incorporated into the coenzyme nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The aim of this study was to determine the concentration of NAD and NADP in the blood of cows during the application of niacin in the peripartum period. The value of these vitamins depends on the peripartum week, regardless of the constant exogenous source of niacin.

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.

Pigs belong to a rare group of domestic animals that are bred only for one type of product - meat. There is a difference between open and closed rearing systems in organic pig farming. An open rearing system means keeping sows outdoors during whole year, which means in summer when pigs are exposed to high temperatures and in winter when they are exposed to rain, snow and wind. Therefore, it is recommended to make a shelter in the area where the sows are staying, where they will take shelter from unfavorable weather conditions. The closed rearing system largely limits natural movements and movements, and especially activities due to the urge to digging. The most common systems of facilities for housing sows are two-part, three-part and the so-called stolba pen.

The aim of this paper is to describe complex homeoretic and homeostatic mechanisms in dairy cows during the peripartum period. The endocrine system has a key function in regulating the adaptation of metabolism during the peripartum period. Homeoresis represents the functioning of the endocrine system and metabolism in conditions when the organism must primarily provide certain physiological processes, such as fetal growth or lactation. Then the function of all tissues is adjusted to the new situation. Homeoretic hormones (growth hormone, prolactin, glucocorticosteroids, thyroid hormones, insulin, glucagon and leptin) in dairy cows in the peripartum period play a key role in maintaining high lactation and maintaining cow health.

The analysis of impact that breeding area, year of birth, calving season and interaction between breeding area and calving season have on milk and milk fat production in full lactations was performed in 241 Simmental cows, with 897 lactations born in period from 1998 to 2007 and distributed into three breeding areas (Čačak, Zlatibor and Rudno). According to applied model, analysis of the influence of paragenetic factors, imapct of breeding area and interaction of breeding area and calving season on the production of milk and milk fat in full lactation was very significant (P<0.01). The year of birth did not significantly impact (P>0.05) the production of milk and milk fat, while the calving season significantly impacted (P<0.05) the production of milk and insignificantly (P>0.05) the production of milk fat in full lactation. Coefficients of determination were very significant (P<0.01) and ranged from 0.431 (43.1%) in milk fat production to 0.500 (50%) in milk production.

The objective of this study was to investigate a possible relationship between blood parameters related to animal welfare and defined beef meat quality characteristics during winter and summer seasons in one small-scale slaughterhouse. At exsanguination, blood samples were collected, and serum concentrations for total proteins (TP), albumin and C-reactive protein (CRP) were evaluated. After 24 h of chilling, ultimate pH was measured and meat samples were used for drip loss and cooking loss determination. Dehydration was not observed during seasons, while elevated concentrations of TP accompanied by higher CRP values pointed to summer as a more stressful season. Analysing the meat quality parameters, it was observed that during the two seasons, ultimate pH values were in the range for normal meat acidification, but values for drip and cooking loss were significantly increased during the summer season. In conclusion, CRP could be used as potential biomarker for beef meat quality estimation, in the first instance drip loss and ultimate pH.