Прегледај по Аутор "Djoković, Radojica"

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    ENDOCRINE AND METABOLIC STATUS IN DAIRY COWS DURING TRANSITION PEROD AND MID LACTATION
    (Lithuanian Veterinary Academy, 2015) Djoković, Radojica; Kurćubić, Vladimir; Ilić, Zoran; Cincović, Marko; Petrović, Milun; Lalović, Miroslav; Jašović, Boban
    The objective of the present study was to evaluate the endocrine and metabolic changes in Simmental dairy cows during the transition period and mid lactation. Fifteen late pregnant cows, 15 early lactation cows and 15 mid lactation cows were chosen for the analysis. Blood samples were collected to measure growth hormone (GH), insulin, triiodothyronine (T3) and thyroxine (T4) by ELISA methods and beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), glucose, triglycerides (TG), total protein (TP), albumin and urea by different colorimetric techniques. Early lactation cows were found to have higher blood serum concentrations of GH (P < 0.05), NEFA (P < 0.05) and BHB (P < 0.05) and lower blood serum concentrations of insulin (P > 0.05), T3 (P < 0.05), T4 (P > 0.05) , glucose (P < 0.05), TG (P < 0.05), albumin (P < 0.05) and urea (P < 0.05) compared to late pregnant and mid lactation cows. Correlation analysis showed that GH levels were negatively correlated with insulin levels (r=-0.44; P < 0.05) and positively with NEFA levels (r=0.32; P < 0.05). Insulin levels negatively correlated with NEFA levels (r=-0.34; P < 0.05) and positively with T3 levels (r=0.35; P < 0.05). BHB was negatively correlated with glucose (r=-0.47; P < 0.05) and TG (r=-0.36; P < 0.05) levels (r=-0.44; P < 0.05) and positively with NEFA levels (r= 0.39; P < 0.05). These endocrine and metabolic changes can serve as useful indicators in evaluating the endocrine and metabolic status of dairy cows during lactation.
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    Endocrine and Metabolic Status of Dairy Cows during Transition Period
    (Chulalongkorn University, Thailand, 2014) Djoković, Radojica; Cincović, Marko; Kurćubić, Vladimir; Petrović, Milun; Lalović, Miroslav; Jašović, Boban; Stanimirovic, Zoran
    The objective of this study was to determine blood levels of cortisol, insulin, triiodothyronine (T3), thyroxine (T4), glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), triglycerides (TG) and total cholesterol in dairy Holstein cows (n = 40) during the transition period. The test cows were classified into four groups: Group A (n = 10), clinically healthy late-pregnant cows from day 20 to day 10 before calving. Group B (n = 10), clinically healthy late-pregnant cows from day 10 to day 1 before calving. Group C (n = 10), clinically healthy puerperal cows. Group D (n = 10), puerperal ketotic cows. The blood serum of ketotic cows was found to have lower levels of T3 (p < 0.01), T4 (p < 0.05), insulin (p > 0.05), cortisol (p > 0.05), glucose (p < 0.01), TG (p <0.01) and total cholesterol (p < 0.05), and higher (p < 0.01) levels of NEFA and BHB, as compared to the blood levels in healthy pregnant and healthy puerperal cows. Results suggest that ketotic cows undergo homeorhetic adaptation of the regulation of organic nutrient metabolism being manifested through a decrease in the blood levels of the test hormones, resulting in increased lipomobilization, hypoglycemia, and intensive ketogenesis and lipogenesis in liver cells.
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    Estimation of Insulin Resistance in Healthy and Ketotic Cows during an Intravenous Glucose Tolerance Test
    (Faculty Of Veterinary Science, University Of Agriculture, Pakistan, 2017) Djoković, Radojica; Dosković, Vladimir; Cincović, Marko; Belić, Branislava; Fratrić, Natalija; Jašović, Boban; Lalović, Miroslav
    The objective of this study was to determine insulin resistance in healthy (n=8) and ketotic (n=7) dairy cows based on the difference between basal and dynamic changes in glucose, insulin, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB) concentrations, and on the determination of their mutual relationship and relationship with insulin resistance indices (RQUICKI and RQUICKI-BHB), after intravenous glucose tolerance test (IVGTT). The RQUICKI index showed a significant linear correlation (P<0.05) with basal insulin, glucose, NEFA and BHB levels. However, RQUICKI-BHB index values exhibited a negative correlation (P<0.01) with basal NEFA and BHB values and their clearance rates, as well as with glucose clearance rate, and a positive correlation (P<0.05) with basal insulin values as well as with insulin and glucose responses during IVGTT. The correlation between basal values of these parameters and the values measured or calculated during IVGTT is the result of RQUICKI-BHB values, as the exclusion of RQUICKI-BHB leads to loss of the statistical significance of the correlations between basal and dynamic values. Insulin resistance in ketotic cows is characterized by decreased insulin response to glucose and increased insulin resistance of the tissue, their correlation being the result of the RQUICKI-BHB index value.
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    Niacin Status Indicators and Their Relationship with Metabolic Parameters in Dairy Cows during Early Lactation
    (MDPI, 2022) Petrović, Kosta; Djoković, Radojica; Cincović, Marko; Hristovska, Marija; Lalović, Miroslav; Petrović, Miloš; Majkić, Mira; Došenović Marinković, Maja; Anđušić, Ljiljana; Devečerski, Gordana; Stojanović, Dragica; Štrbac, Filip
    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.