Niacin, Metabolic Stress and Insulin Resistance in Dairy Cows

The periparturient period in cows is associated with metabolic stress and a state of negative energy balance, which are characterized by increased lipolysis, ketogenesis, hepatic steatosis, oxidative stress and insulin resistance. Such metabolic changes may exert adverse effects on the health and milk yield of lactating cows. The pharmacokinetics of niacin in ruminants is specific as rumen microorganisms facilitate both the synthesis of tryptophan and the degradation of niacin. Niacin administration to cows leads to an increase in the coenzyme activity, encompassing the activity of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes are actively involved in the metabolism of lipids and carbohydrates, whereas NAD protects the organism from oxidative stress. In periparturient cows, the supplementation of niacin has been found to induce depressed lipolysis and a limited impact of nonesterified fatty acids on all metabolic processes. It also results in decreased lipid peroxidation regardless of the magnitude of lipolysis in the periparturient period. Furthermore, niacin reduces the concentration of ketone bodies, thus preventing the development of fatty lever disease and ketosis in cows. The anti-inflammatory effect of niacin is manifested in stimulating the secretion of adiponectin and inhibiting immune cells

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

Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

Insulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the first week after calving. Indexes of insulin resistance valued: 18.68 +/- 5.43 (HOMA), 0.39 +/- 0.06 (QUICKI) and 0.45 +/- 0.06 (RQUICKI). Linear correlations were examined by testing the coefficient of correlation (r), determination (r(2),%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=-0.51, r(2)=25.0, b=-1.1257, p<0.01). HOMA showed a positive correlation with BHB (beta-hidroxybutyrate) (r=0.48, r(2)=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r(2)=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r(2)=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r(2)=27.1, b=-1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r(2)=20.9, b=-2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r(2)=22.8, b=28.1230, p<0.01), T4 (r=0.47, r(2)=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r(2)=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=-0.36, r(2)=13.0, b=-9.0332, p<0.05), STH (somatotropic hormone) (r=-0.42, r(2)=17.3, b=-5.4976, p<0.01), BHB (r=-0.62, r(2)=38.3, b=-1.1872, p<0.01), total bilirubin (r=0.58, r(2)=33.7, b=-7.131, p<0.01) and BCS (body condition score) (r=-0.6, r(2)=36.4, b=1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process

Određivanje aktivnosti specifičnih enzima krvi u peripartalnom periodu i tokom pune laktacije

This study examined the activities of aspartate-aminotransferase (AST), gamma-glutamyl-transferase (GGT) and lactate-dehydrogenase (LDH) in the blood serum of 45 dairy Simmental cows divided into three groups according to production period. The first group (n=15) consisted of late pregnant dairy cows, the second group (n=15) cows in the early lactation, and the third group (n=15) cow in mid lactation. The significant higher activity (P (lt) 0.05) of AST, GGT and LDH were determined in the early lactation period than in dry period and during full lactation. Research results showed possibility of mild degree of hepatic lesions, probably due to fat infiltration in early lactation cows. Serum AST enzyme activities were significant correlated (P (lt) 0.05) with GGT and LDH activities and may be most sensitive indicator.U ovom radu je određivana aktivnost aspartat-aminotransferaze (AST), gama-glutamat-transferaze (GGT) i laktat dehidrogenaze (LDH) u krvnom serumu kod 45 simentalskih mlečnih krava, podeljenih u tri grupe u zavisnosti od produktivnog perioda. Prvu grupu (n=15) su činile visoko gravidne krave, drugu grupu (n=15) krave u ranoj laktaciji, a treću grupu (n=15) krave tokom pune laktacije. Statistički značajno veće aktivnosti AST (P (lt) 0.05),GGT (P (lt) 0.05) i LDH (P (lt) 0.05) u krvnom serumu su utvrđene kod krava u ranoj laktaciji u odnosu na aktivnosti ovih enzima u serumu kod zasušenih krava i krava u punoj laktaciji. Dobijeni rezultati ukazuju na mogućnost blagog stepena oštećenja ćelija jetre, odnosno masnu infiltraciju hepatocita kod krava na početku laktacije. Serumske aktivnosti AST su bile u značajnoj korelaciji (P (lt) 0.05) sa aktivnostima GGT i LDH u krvnom serumu pa se AST može smatrati pouzdanim indikatorom u tvrđivanju funkcionalnog stanja jetre kod mlečnih krava tokom peripartalnog perioda i pune laktacije

Vučna čvrstoća resorptivnog šivaćeg materijala primijenjenoga u rekonstrukciji stijenke želuca - in vitro istraživanje

The primary objective of this study was to determine whether polyglyconate or polydioxanone resorptive surgical materials are superior in terms of tensile strength retention in implantation in the cadaveric submucosa of the stomach wall. A secondary objective was to compare the tensile strength retention, in the same conditions, of polydioxanone suture materials produced by different manufacturers. Five samples of resorptive suture materials (polyglyconate (Maxon®, Covidien), polydioxanone (PDS®, Ethicon, PDX® Kruuse, Surgicryl® SMI), Catgut chromic, Kruuse) all diameter USP 2-0, were incubated in vitro in the cadaveric submucosa of the stomach wall for fifty days. Measurements of tensile strength were made on day 0 and the 10th day. Polyglyconate (Maxon®) showed the greatest initial tensile strength. After 10 days of incubation in the submucosa of the stomach, the tensile strength decreases more rapidly for polyglyconate (Maxon®) in comparison to polydioxanone sutures, but they were still higher compared with the others on the 10th day. Polydioxanone Surgicryl® had the highest tensile strength retention - 91.4% after 10 days of incubation in the submucosa of the stomach. Polydioxanone PDX® maintained only 58.5% of its initial tensile strength. Polydioxanone Surgicryl® had the highest initial Young’s modulus.Primarni cilj ovog istraživanja bio je odrediti koji je od resorptivnih materijala za šivanje, poliglikonat ili polidioksanon, bolji s obzirom na zadržavanje vučne čvrstoće konca, a nakon implantiranja u submukozu želučane stijenke. Sljedeći je cilj bio usporediti vučnu čvrstoću konaca sastava polidioksanon, različitih proizvođača, u istim uvjetima. Pet uzoraka resorptivnih materijala za šivanje, poliglikonat (Maxon®, Covidien), polidioksanon (PDS®, Ethicon, PDX® Kruuse, Surgicryl® SMI), Catgut chromic, Kruuse, svi istoga promjera USP 2-0, implantirani su u sluznicu želučane stijenke lešine kunića tijekom 10 dana. Određivanje vučne čvrstoće izvedeno je nulti i deseti dan. Poliglikonat (Maxon®) pokazao je najveću početnu vučnu čvrstoću. Nakon 10 dana inkubiranja u submukozi želučane stijenke poliglikonat (Maxon®) brže je gubio vučnu čvrstoću u usporedbi s koncima sastava polidioksanon, ali je zadržao veću vrijednost vučne čvrstoće. Polidioksanon (Surgicry®) nakon 10 dana inkubiranja u submukozi želučane stijenke imao je najveći postotak (91,4 %) zadržavanja početne vučne čvrstoće. Polidioksanon (PDX®) zadržao je samo 58,5 % početne vučne čvrstoće. Polidioksanon Surgicryl® imao je najveći početni Youngov modul elastičnosti

Influence of claw disorders on milk production in Simmental dairy cows

A study on claw disorders’ infl uence on milk production was performed during one year on 226 Simmental loose-reared cows. The first trial group included 42, the second 37, and the third 34 cows, with claw changes observed in the first hundred days of lactation, between days 101 and 200, between days 201 and 305, respectively. The control group included 113 cows with no observed changes. Lameness intensity was assessed once a week. Milk yield data were collected three weeks before, in the week of treatment of claws and three weeks afterwards. There were significantly more cows with lameness in the third group than in the other two groups, as well as the most cows with one aff ected limb in the first hundred days of the lactation (P<0.05). Significantly fewer cows with two aff ected limbs were present in the first group. In the second group, more cows were observed with two aff ected limbs than in the first group (P<0.05). In the third group, more cows with three or four aff ected limbs were noticed than in the other groups. The most common claw disorders were: solar ulcer, laminitis, dermatitis digitalis and overgrown claws. Cows whose claws were aff ected between days 101 and 200 of lactation period produced 231 kg less milk than those of the control group; cows whose claws were aff ected in the last third of lactation produced 26 kg less milk. Nevertheless, no significant diff erences were found between milk yields of the control and trial groups (P>0.05). Cows aff ected in the first third of lactation produced less milk (324 kg) than both healthy and cows with claw changes manifested in later stages of lactation. Obtained data confirm that claw disorders may aff ect dairy production

Relationship of Circulating Tumor Necrosis Factor Alpha (TNF-α) and Insulin Secretion and Resistance in Euglycaemic Dogs

Background: Insulin resistance is a state that is characterized with reduced sensitivity of peripheral tissues to insulin. It can be related with increased level of tumor necrosis factor alpha (TNF-α) in dogs. Insulin resistance can be evaluated by homeostasis model assessment (HOMA-IR, HOMA-β). The aim of this study was to determine correlation of circulating TNF-α level with insulin production and insulin resistance indexes in euglycaemic dogs. Materials, Methods &amp; Results: Seventydogs of normal body score were included in this study. After blood sampling levels of glucose, insulin and TNF-α were determined and indexes HOMA-IR and HOMA-β were calculated. Three groups in accordance to TNF-α levels were formed: the first-TNF-α 0-2.0 pg/mL, the second-TNF-α below median (2.1-17.0 pg/mL) and the third-TNF-α above median (17.1-51.8 pg/mL). Differences in insulin and glucose levels, HOMA-IR and HOMA-β were determined in all three groups. ANOVA and posthock LSD analyses were used. Correlation between HOMA-IR and HOMA-β was determined. Linear regression between HOMA-β/HOMA-IR ratio and glucose concentration was calculated. SPSS statistical program was used (IBM). Highest insulin level was detected in the second group and the lowest was detected in the third group. The lowest glucose level was detected in the first group. The highest value of HOMA-β index was noted in the first group and it decreases with TNF-α increase. The highest HOMA-IR value was detected in the second group and the lowest was in the third group. Positive correlation was noted between HOMA-IR and HOMA-β. Significant linear correlation was noted between glucose levels in function of HOMA-β/HOMA-IR (R2= 0.51-0.78, P = 0.0007). The first group showed the minor change of glucose level (b= 0.29 mmol/L). In the third group the greatest change of glucose level in function of HOMA-β/HOMA-IR was noted (b= 0.52 mmol/L). In the third group the highest increase of glucose level followed by decrease in HOMA-β/HOMA-IR ratio was noted.  Discussion: Increase of TNF-α followed by increase of insulin was noted in the second group. That indicates reduced insulin action and compensatory increase in his concentrations in order to achieve the same effect. TNF-α induces reduction in expression of glucose transporter 4 that is insulin-regulating hormone. Serine phosphorylation of insulin receptor substrate-1 that is induced by TNF-α causes inhibition of insulin receptors. These actions cause insulin resistance and compensatory increase in insulin secretion. Increased tissue resistance is reflected in increased HOMA-IR index which is directly associated with insulin and glucose level. Increase of insulin value and HOMA-IR index were noted in second group. This indicates the influence of TNF-α on insulin resistance. The lowest insulin level was noted in the third group of dogs. Decrease in production and secretion leads to reduction in circulating insulin and can be evaluated by HOMA-β index. The highest value of this index was noted in first group and decreases with TNF-α increase. This can be related with apoptotic effect that TNF-α has on beta- pancreatic cells. Increase of HOMA-β index causes increase of HOMA-IR. This is indication of increased peripheral resistance. Compensatory mechanism for that state is increased insulin secretion. Glucose level will increase more during increase of HOMA-IR and decrease of HOMA-β. This indicates that TNF-α regulates glucose level directly and explains differences in glucose concentrations in dogs with different concentrations of TNF-α showed. Values of insulin resistance indexes, glucose and insulin were affected by circulating concentration of TNF-α. The most unfavorable change in glucose concentration based on insulin production and tissue resistance was founded in dogs with the highest circulating TNF-α concentration in blood.

Influence of ketoprofen application on lipid mobilization, ketogenesis and metabolic status in cows during early lactation

© 2016 Veteriner Fakultesi Dergisi. All rights reserved. Changes in metabolic functions in transition dairy cows represent a result of negative energy balance. This leads to increased lipid mobilization and ketogenesis, followed by increased concentrations of non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB). Hence, high lipid mobilization and ketogenesis modulate inflammation response and vice versa. The aim of this study was to investigate correlations between ketoprofen administration, high lipid mobilization, ketogenesis and characteristics of metabolic adaptation in cows. Ketoprofen was administered intramuscularly in the concentration of 3 mg/kg, during three consecutive days in 15 postpartum cows. The control group included 15 cows which were not treated with ketoprofen. Blood samples were taken from coccygeal vein, after calving, in the first and second week of the postpartum period. When compared with control, ketoprofen administration decrease the levels of NEFA, BHB and total bilirubin, increase levels of glucose, albumin and cholesterol. Our results showed decreased activity of AST in ketoprofen treated cows in comparison with control group. There was an increase in the intensity of lipolysis and ketogenesis in 66.7% of cows, with NEFA and BHB values over the optimal results, because ketoprofen was not applied to these animals. Cows in the control group were 2 or 2.4 times more likely to come to a state of increased lipid mobilization and ketogenesis. We have found high concordance between NEFA and BHB, and metabolic parameters. This correlation was lower in experimental group of cows hence we can conclude that the use of ketoprofen immediately after calving reduces lipid mobilization and ketogenesis during early lactation and the metabolic adaptation dependence on the intensity of these two processes

Prosudba metaboličkog statusa mliječnih krava simentalske pasmine tijekom kasne gravidnosti i na početku laktacije.

The objective of this experiment was to evaluate the metabolic status of late pregnant and early lactation dairy cows based on changes in characteristic blood metabolites. Blood samples were collected from 15 late pregnant cows and 15 early lactation cows to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), glucose, total protein (TP), albumin, total bilirubin, urea and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase (GGT). Cows in early lactation had significantly higher (P0.4 mmol/L) was detected in 6 (40%) of early lactation cows but in none of the late pregnant cows, while subclinical ketosis (BHB>1.2 mmol/L) was detected in 14 (94.4%) of the early lactation cows and 4 (26.6%) of the late pregnant cows. AST activities above 100 U/L were detected in 2 early lactation cows and in none of the late pregnant cows. TG levels below 0.12 mmol/L and glucose below 2.5 mmol/L were found in 7 (44%) and 10 (66.6%) of the early lactation cows, respectively, and in none of the late pregnant cows. Early lactation cows were found to have lower blood serum levels of TG (P0.05) activities and higher concentrations of total bilirubin (P>0.05) TP (P>0.05) and AST activities (P0,4 mmol/L) utvrđene su u 40% krava na početku laktacije, ali u nijedne visoko gravidne krave, dok je supklinička ketoza utvrđena (BHM>1,2 mmol/L) kod 14 (94,4%) krava na početku laktacije te kod 4 (26,6%) visoko gravidnih krava. Aktivnost AST u krvnom serumu iznad 100 U/L utvrđena je u dvije (13,3%) krave na početku laktacije, a nije utvrđena u krava u kasnoj gravidnosti. Vrijednosti TG u krvi bile su ispod 0,12 mmol/L u sedam (44%), a glukoze ispod 2,5 mmol/L u 10 (66,6%) krava na početku laktacije dok nisu dokazane u krava u visokoj gravidnosti. Uspoređujući funkciju jetre, u krvnom serumu krava na početku laktacije utvrđene su niže vrijednosti TG (P0,05), odnosno veće vrijednosti ukupnog bilirubina (P>0,05), TP (P>0,05) i aktivnosti AST (P<0,05) u odnosu na vrijednosti ovih pokazatelja krvi kod krava u visokom stupnju gravidnosti. Vrijednosti glukoze, BHB, NEFA, TG i aktivnosti AST u krvnom serumu upućuju na zaključak da su krave na početku laktacije opterećene metaboličkim poremećajima koji su povezani s ketozom i određenim stupnjem oštećenja hepatocita, vjerojatno, kao posljedica masne infiltracije. Navedeni pokazatelji krvi mogu biti od velikog značenja u procjeni metaboličkog statusa mliječnih krava u peripartalnom razdoblju

Efficiency of two protocols of resynchronization of estrus and ovulation in high-producing dairy cows at peak lactation

The reproductive efficiency of the cows was monitored after two resynchronization protocols: Ovsynch (OVS) and Double Ovsynch (DOS). The research initially included 70 HF cows who entered the first synchronization protocol - Presynch. Cows that did not conceive after the first synchronization were divided into two groups and introduced to two resynchronization protocols. In the first group of cows (n=35), the DOS protocol began with the application of GnRH on day 22 after the Presynch TAI (Timed Artificial Insemination), and seven days later pregnancy check-up was done and PGF2α was applied only to non-pregnant cows (n=23), which remained in the study. In the second group of cows, the OVS protocol started on day 32 after Presynch TAI only in non-pregnant animals (n=20). Progesterone (P4) concentration was determined at the time of application of GnRH1, PGF2α and GnRH2 in both groups of cows, and then 30 days after Resynch TAI, ultrasound pregnancy diagnosis was done. A higher percentage of pregnant cows were recorded in the OVS group compared to the DOS group (45% and 35%, respectively). The concentration of P4 in the serum of cows in the DOS group during the first measurement (GnRH1) was significantly higher than the value in cows that did not conceive (p<0.05), while in the third measurement (GnRH2) the average concentration of P4 in conceiving cows was significantly lower (p<0.001) compared to cows that did not coincive. The open days period was significantly longer in pregnant cows that were resynchronized using the DOS protocol compared to cows from the OVS protocol. In conclusion, the OVS protocol of estrus resynchronization in dairy cows proved to be more successful than the DOS protocol. However, considering the advantages the OVS, it is needed to determine which day of the sexual cycle is the best to start resynchronization