Concentrations In Calves Research Articles

Effect of Suckling Systems on Serum Oxytocin and Cortisol Concentrations and Behavior to a Novel Object in Beef Calves.

We investigated differences between effects of natural- and bucket-suckling methods on basal serum oxytocin (OT) and cortisol concentrations, and the effect of OT concentration on affiliative and investigative behavior of calves to a novel object. Ten Japanese Black calves, balanced with birth order, were allocated evenly to natural-suckling (NS) and bucket suckling (BS) groups. Blood samples were collected at the ages of 1 and 2 months (1 week after weaning) calves, and serum OT and cortisol concentrations were measured using enzyme-linked immunosorbent assay and enzymeimmunoassay tests, respectively. Each calf at the age of 2 months (2 weeks after weaning) was released into an open-field with a calf decoy, and its investigative and affiliative behaviors were recorded for 20 minutes. In 1-month-old calves, the basal serum OT concentration (25.5±4.9 [mean±standard deviation, pg/mL]) of NS was significantly higher than that of BS (16.9±6.7) (p<0.05), whereas the basal cortisol concentration (5.8±2.5 [mean±standard deviation, ng/mL]) of NS was significantly lower than that in BS (10.0±2.8) (p<0.05). Additionally, a negative correlation was noted between serum OT and cortisol concentrations in 1-month-old calves (p = 0.06). Further, the higher serum OT concentration the calves had at 1 month old, the more investigative the calves were at 2 months old but not affiliative in the open-field with a calf decoy. Thus, we concluded that the natural suckling method from a dam elevates the basal serum OT concentration in calves, and high serum OT concentrations induce investigative behavior and attenuate cortisol concentrations.

Plasma anti-Müllerian hormone as a predictive endocrine marker to select Bos taurus (Holstein) and Bos indicus (Nelore) calves for in vitro embryo production

This study evaluated the association between plasma anti-Müllerian hormone (AMH) concentrations and in vitro embryo production in Bos indicus (Nelore; experiment 1) and Bos taurus (Holstein; experiment 2) calves superstimulated or not with 140 mg of porcine follicle-stimulating hormone (pFSH; 4 decreasing doses twice daily). Oocytes were recovered from calves aged 2 to 4 mo after receiving gonadotropin stimulation (Nelore, n = 15; Holstein, n = 12) or not (Nelore, n = 15; Holstein, n = 12). Cycling heifers formed a positive control group (n = 15 for Nelore [aged 18–24 mo], n = 10 for Holstein [aged 14–16 mo]). All the calves underwent laparoscopic ovum pickup, and cycling heifers underwent a regular transvaginal ultrasound-guided ovum pickup for oocyte recovery. Immediately before oocyte retrieval, blood samples were taken for subsequent AMH determination (ng/mL). Regardless of the genetic group, calves that received pFSH (3.6 ± 1.1 in Nelore and 4.6 ± 1.2 in Holstein) or did not receive pFSH (3.2 ± 1.0 in Nelore and 2.5 ± 0.8 in Holstein) had greater plasma AMH concentrations (P = 0.01 in Nelore and P = 0.003 in Holstein) than cycling heifers (1.1 ± 0.2 in Nelore and 0.6 ± 0.07 in Holstein). AMH concentrations in calves with or without pFSH were similar in both genetic groups (3.6 ± 1.1 vs 3.2 ± 1.0 in Nelore; 4.6 ± 1.2 vs 2.5 ± 0.8 in Holstein). In calves, positive correlations were observed between plasma AMH concentrations and the numbers of follicles >2 mm (r = 0.86, P < 0.0001 in Nelore; r = 0.78, P < 0.0001 in Holstein), cumulus-oocyte complexes (COCs) retrieved (r = 0.91, P < 0.0001 in Nelore; r = 0.82, P < 0.0001 in Holstein), COCs cultured (r = 0.71, P < 0.0001 in Nelore; r = 0.79, P < 0.0001 in Holstein), and blastocysts produced (r = 0.62, P = 0.0003 in Nelore; r = 0.58, P = 0.009 in Holstein), and these results were independent of pFSH treatment. In conclusion, calves had greater plasma AMH concentrations than cycling heifers. In addition, treatment with pFSH did not influence AMH concentrations in calves, regardless of the genetic group. More importantly, plasma AMH concentrations were positively correlated with the antral follicle population and the number of COCs retrieved, COCs cultured, and blastocysts produced in B indicus and B taurus calves. Therefore, AMH is a promising tool for selecting oocyte donor calves to maximize results during in vitro embryo production.

Pharmacokinetics of enrofloxacin and ceftiofur in plasma, interstitial fluid, and gastrointestinal tract of calves after subcutaneous injection, and bactericidal impacts on representative enteric bacteria.

This study's objectives were to determine intestinal antimicrobial concentrations in calves administered enrofloxacin or ceftiofur sodium subcutaneously, and their impact on representative enteric bacteria. Ultrafiltration devices were implanted in the ileum and colon of 12 steers, which received either enrofloxacin or ceftiofur sodium. Samples were collected over 48 h after drug administration for pharmacokinetic/pharmacodynamic analysis. Enterococcus faecalis or Salmonella enterica (5 × 10(5) CFU/mL of each) were exposed in vitro to peak and tail (48 h postadministration) concentrations of both drugs at each location for 24 h to determine inhibition of growth and change in MIC. Enrofloxacin had tissue penetration factors of 1.6 and 2.5 in the ileum and colon, while ciprofloxacin, an active metabolite of enrofloxacin, was less able to cross into the intestine (tissue penetration factors of 0.7 and 1.7). Ceftiofur was rapidly eliminated leading to tissue penetration factors of 0.39 and 0.25. All concentrations of enrofloxacin were bactericidal for S. enterica and significantly reduced E. faecalis. Peak ceftiofur concentration was bactericidal for S. enterica, and tail concentrations significantly reduced growth. E. faecalis experienced growth at all ceftiofur concentrations. The MICs for both organisms exposed to peak and tail concentrations of antimicrobials were unchanged at the end of the study. Enrofloxacin and ceftiofur achieved intestinal concentrations capable of reducing intestinal bacteria, yet the short exposure of ceftiofur in the intestine may select for resistant organisms.

Association between birth conditions and glucose and cortisol profiles of periparturient dairy cows and neonatal calves

Parturition in cattle is a stressful event for both the dam and the offspring. Stress and pain can alter the energy profile of calves and calving cows, producing a metabolic...

Serum concentrations of haptoglobin and haptoglobin-matrix metalloproteinase 9 (Hp-MMP 9) complexes of bovine calves in a bacterial respiratory challenge model.

BackgroundSerum haptoglobin (Hp) and haptoglobin matrix metalloproteinase 9 complexes (Hp-MMP 9) have been identified as biomarkers with diagnostic potential in cattle with conditions resulting in an acute inflammatory response. The purpose of this study was to evaluate potential diagnostic applications of serum Hp and Hp-MMP 9 concentrations in calves with BRD and establish a timeline for their detection in calves experimentally challenged with Bibersteinia trehalosi and Mannheimia haemolytica. Thirty-five cross bred dairy calves were inoculated via tracheal catheterization with either a PCR confirmed leukotoxin negative B. trehalosi isolate, a PCR confirmed leukotoxin positive B. trehalosi isolate, a Mannheimia haemolytica isolate, a combination of leukotoxin negative B. trehalosi and M. haemolytica, or a negative control. Serum samples were collected throughout the study. Calves were euthanized and necropsy performed on day 10 post inoculation.ResultsM. haemolytica inoculated calves had increased lung involvement. Serum Hp and Hp- MMP 9 concentrations were elevated compared to the other treatment groups. Increases in serum Hp and Hp-MMP 9 concentrations for the M. haemolytica group were significantly different from other study groups on day 7 of the study. B. trehalosi inoculated calves did not have increased lung involvement compared to control calves, but the leukotoxin positive B. trehalosi group demonstrated increased serum Hp-MMP 9 concentrations from day 3 to the end of the study compared to the pre-inoculation concentrations.ConclusionSerum Hp-MMP 9 concentration is a useful diagnostic tool for detecting early pulmonary inflammation in calves challenged with B. trehalosi and M. haemolytica. Serum Hp-MMP 9 may also be a useful tool in detecting subclinical pulmonary inflammation in challenged calves.

Effect of the mass of immunoglobulin (Ig)G intake and age at first colostrum feeding on serum IgG concentration in Holstein calves

Forty-four Holstein calves (19 male and 25 female) were used in this study of the relationships among age at first colostrum feeding, IgG intake, and apparent efficiency of IgG absorption. Time of birth was recorded for each calf and the calves were fed colostrum ad libitum after birth at either 0930 or 1630h. Blood samples were collected immediately before and 24h after colostrum feeding. Data from calves were then categorized into 4 groups representing time from birth to colostrum feeding: A=fed within 1h (n=5); B=fed from 1 to 6h (n=10); C=fed from 6 to 12h (n=21); and D=fed from 12 to 18h (n=8) after birth. Average total intake of colostrum was 3.6±0.1L. Over 80% of the calves consumed ≥3L of colostrum. Apparent efficiency of IgG absorption declined remarkably 12h after birth. Mean apparent efficiency of absorption of IgG in group D (15.8±3.0%) was lower than that in groups A (30.5±3.9%) and B (27.4±2.8%). Serum IgG concentration in calves was positively correlated with IgG intake in all groups. The relationship between mass of IgG consumed and calf serum IgG at 24h was different for each time of colostrum feeding, with only limited differences observed between groups A and B. We concluded that failure of transfer of passive immunity in newborn calves may be avoided if calves consume ≥3L of colostrum with IgG concentration >40mg/mL within 6h after birth. These findings help define the opportunity to minimize failure of transfer of passive immunity to newborn calves under management programs similar to those used on commercial dairy farms.

Effect of adding gut-active carbohydrates to fresh colostrum on passive transfer of immunoglobulin G in Holstein dairy calves

Lower concentrations of coliform bacteria in maternal colostrum (MC) have been associated with enhanced IgG absorption in calves. Mannan-oligosaccharide, a gut active carbohydrate (GAC) derived from yeast cell walls, can adsorb pathogens expressing type-1-fimbriae, which reduces their ability to colonize the gastrointestinal tract. Results of preliminary research suggest that feeding GAC in colostrum enhanced serum IgG concentration in calves. The purpose of this study was to investigate whether addition of a GAC (Bio-MOS®. Alltech, Inc.) to colostrum would increase IgG absorption in newborn calves.

The serum protein electrophoretic pattern and acute phase protein concentrations in calves with chronic respiratory diseases

The aim of this study was to evaluate the serum protein electrophoretic pattern and the concentrations of acute phase proteins (haptoglobin, serum amyloid A, and fibrinogen) in 28 calves with clinical signs of chronic respiratory diseases and 36 healthy calves as a control group. In sick calves we found significantly higher serum concentrations of total proteins (P < 0.001), lower concentrations of albumin (P < 0.001) and marked shift in the concentrations of the most of protein fractions with significantly higher values of alpha1-, beta1-, beta2-, and gamma-globulins (P < 0.001 and P < 0.01). The affected calves had significantly higher values of haptoglobin, serum amyloid A, and fibrinogen as well (P < 0.05, P < 0.001 and P < 0.001, respectively).

The serum protein electrophoretic pattern and acute phase proteins concentrations in calves with chronic respiratory diseases

The aim of this study was to evaluate the serum proteins electrophoretic pattern and the concentrations of acute phase proteins in calves with chronic bronchopneumonia. Twenty-eight calves with clinical symptoms of disease were included into the evaluation. Blood serum was analyzed for total protein concentrations (TP), total and relative values of serum protein fractions, albumin/globulin ratio (A/G) and the concentrations of selected acute phase proteins - haptoglobin (Hp), serum amyloid A (SAA), and fibrinogen (Fbg). The results recorded in sick animals were compared with those in 36 clinically healthy calves as control group. In calves suffering from chronic bronchopneumonia we found significantly higher total serum protein concentrations than in healthy calves (p<0.001). In sick calves a marked shift in the concentrations of most of the protein fractions was observed, with significantly higher mean total values of α1- (p<0.001), β1- (p<0.01), β2- (p<0.001), and γ-globulins (p<0.001) and relative mean values of α1- (p<0.01), β2- (p<0.01), and γ-globulins (p<0.001). On the other hand, the concentrations of albumin and A/G ratios were in calves with respiratory diseases significantly lower than those measured in healthy ones (p<0.001). The mean concentrations of α2- globulins did not differ significantly between the two groups of animals. In the affected calves significantly higher mean values of Hp, SAA, as well as Fbg (p<0.001) were described. The presented results suggest a marked effect of chronic bronchopneumonia in calves on most of the evaluated protein profiles and acute phase protein variables with a marked shift in the albumin and globulin concentrations.

Effects of intravenous ghrelin injection on plasma growth hormone, insulin and glucose concentrations in calves at weaning

Ghrelin action, which stimulates growth hormone (GH) secretion, may alter during the weaning period in calves. Our objective was to compare the effects of intravenous ghrelin injection on plasma GH, insulin and glucose concentrations in calves around the weaning period. Four Holstein bull calves were fed whole milk and allowed free access to solid feeds, and weaned at 7 weeks of age. Measurements were performed at weeks 1, 2, 4, 6, 7, 9, 11 and 13, when calves were intravenously injected with ghrelin (1.0 μg/kg body weight (BW)) through a catheter, and jugular blood samples were obtained temporally relative to the injection time. Estimated digestible energy intake per metabolic BW transiently decreased at week 7 because of low solid intake immediately after weaning, and thereafter gradually increased. Plasma insulin and glucose concentrations were not affected by ghrelin injection at all ages. In contrast, plasma GH concentrations increased with ghrelin injection at all ages. The incremental area of GH at week 7 was greatest and significantly higher compared with weeks 2, 4, 6 and 9. This result suggests that nutrient insufficiency immediately after weaning enhances GH responsiveness to ghrelin.

Disturbances in the acid-base and electrolyte balance and changes in serum mineral concentrations in calves diagnosed with nutritional muscular dystrophy

Selenium is an essential nutrient, which is crucial for proper body function. Its role is complemented by vitamin E. Nutritional muscular dystrophy (NMD) is one of the main disorders caused by a selenium deficiency. NMD most often affects calves at the age of 4 to 6 weeks. The study was performed on 40 Holstein-Friesian (HF) calves divided into two groups of 20 animals each. Control group calves were administered an IM injection of selenium and vitamin E on the second day of life. The experimental group comprised calves with symptoms of NMD. Samples of the biceps femoris muscle were collected from six animals in each group for histopathological analyses to confirm changes in muscle parameters. Blood samples were obtained from all animals on three different dates. The following blood parameters were determined in laboratory analyses: pH, pCO 2 , pO 2 , HCO 3 – , BE, O2SAT, the concentrations of Na + , K + , Cl – , and Ca and P levels. A drop in pH, an increase in the partial pressure of carbon dioxide, a decrease in the partial pressure of oxygen, a significant decrease in bicarbonate ion concentrations and hemoglobin oxygen saturation as well as a base deficit were reported in the group of calves demonstrating symptoms of NMD. The above changes point to the development of uncompensated metabolic acidosis due to increased levels of pyruvic acid and lactic acid produced as a result of anaerobic processes that accompany muscle fiber degeneration. Minor fluctuations in sodium and chloride levels were observed throughout the experiment, but their concentrations remained within the norm in animal groups. Potassium levels were significantly hi

Evaluation of serum immunoglobulin G concentrations in dairy calves by use of an automated turbidimetric immunoassay

Administration of colostrum to newborn calves is recognized as an important component of dairy calf health maintenance because colostral immunoglobulin absorption is required to establish passive immunity. Despite the importance of a good colostrum management program, over one-third of dairy operations still depend on the calf nursing the dam as the only method for colostrum delivery, and 19.2% of calves are estimated to have failure of transfer of passive immunity. Multiple assays have been described to assess serum immunoglobulin G (lgG) concentrations in calves; however, none are ideal for routine use on farms. The purpose of this study was to evaluate the reliability of a new commercially available automated turbidimetric immunoassay and portable analyzer for measuring serum IgG concentrations in dairy calves.

Serum immunoglobulin (IgG, IgM, IgA) concentration in cows and their calves

The objective of this study was to determine the relation between the immunoglobulin (Ig) concentration in the cow serum and colostrum and subsequent Ig concentrations in the calf serum. Black and White dairy cows (n = 64) and their calves were examined. Blood samples were taken from cows at approximately 1 month prepartum and 8 weeks postpartum and from calves at the age of 1 and 4 weeks. First milking colostrum samples were obtained. The IgG, IgM and IgA concentrations in the serum samples were measured with the quantitative ELISA. The colostrum Ig concentration was measured with colostrometer. The descriptive statistics and correlation coefficients by Pearson were calculated. Statistically significant positive correlations were established between the serum IgG concentrations in cows and their calves, and between the Ig concentration in the colostrum and serum of calves. Statistically significant positive correlations were established between the IgG (r = 0.386, P = 0.001) and IgA (r = 0.350, P = 0.004) concentrations in calves at the age of 1 and 4 weeks. There was no significant correlation between the Ig concentration in colostrum and IgG, IgM and IgA concentrations in the cows’ serum. Calf serum IgG and IgA obtained in the 1st week showed a positive relationship with the IgG concentration in the serum and colostrum of the cows. Positive correlations between IgG and IgA in the calf serum in the 1st and 4th week of life indicate that calves with a higher Ig concentration in the 1st week also have a higher Ig level later when they already produce their own immunoglobulin.

Effects of glucose and volatile fatty acids on blood ghrelin concentrations in calves before and after weaning1

The effects of feeding and intravenous injections of glucose and VFA on blood ghrelin concentrations were investigated in calves before and after weaning. Eight Holstein bull calves were fed whole milk, allowed free access to solid feeds, and weaned at 7 wk. Measurements were carried out at 2, 4, 6, 9, 11, and 13 wk, at which time jugular blood samples were taken from 4 calves through a catheter from 10 min before to 120 min after their morning feed at 10 min intervals (Exp. 1). An additional 4 calves of the same age were intravenously injected with glucose (1.0 mmol·kg BW(-1)) and a solution of VFA (2.4 mmol·kg BW(-1), acetate:propionate:butyrate in a 6:3:1 ratio) using a catheter, and jugular blood samples were taken temporally relative to the injection time (Exp. 2). In Exp. 1, blood ghrelin concentrations decreased (P < 0.05) after feeding at all ages. However, preprandial ghrelin concentrations were less (P = 0.025) and the degree of postprandial depression of ghrelin tended to be greater during the postweaning period (P = 0.084) than during the preweaning period. Blood glucose concentrations increased after feeding during the preweaning period (P < 0.05), whereas blood acetate concentrations increased during the postweaning period (P < 0.05). In Exp. 2, injection of VFA induced a greater decrease in blood ghrelin concentrations than glucose injection throughout the entire period (P < 0.05). These results indicate that weaning reduces the basal concentration of blood ghrelin because the circulating VFA derived from ruminal fermentation may more strongly depress blood ghrelin concentrations than glucose.

Short communication: Evaluation of serum immunoglobulin G concentrations using an automated turbidimetric immunoassay in dairy calves

The absorption of maternal antibodies associated with colostrum feeding is critical to the health of calves. Multiple assays have been described to assess serum immunoglobulin G (IgG) concentrations in calves. However, none are ideal for routine use on farms. The purpose of this study was to evaluate the reliability of a new commercially available immunoassay and portable analyzer for measuring serum IgG concentrations in dairy calves. Serum from 100 Holstein calves that had received colostrum was collected for this study. Immunoglobulin G concentrations were run on each calf using both the rapid immunoassay method and radial immunodiffusion assay. Serum IgG concentrations in calves from this study ranged from 460 to 3,640mg/dL (mean ± SD: 1,515±71) as measured by radial immunodiffusion and 402 to 3,586mg/dL (mean 1,473±70) as measured by the immunoassay. Based on regression analysis, the automated results closely paralleled those obtained by radial immunodiffusion with a coefficient of determination value of 0.98. Based on the results of this study, the immunoassay technique using the portable analyzer represents a reliable method that can be run within 15min and provide an accurate serum IgG level. Although the cost is not insignificant, this assay could be easily implemented on a dairy farm to help monitor transfer of passive immunity.

Cardiac Troponin I in Calves with Congenital Heart Disease

The association between plasma cardiac troponin I (cTnI) and the magnitude of cardiac enlargement in calves with congenital heart disease (CHD) are not well defined. To investigate the relationship between plasma cTnI concentrations and cardiac size in healthy calves and calves with CHD. A total of 19 healthy calves (control) and 12 Holstein calves with CHD (patent ductus arteriosus, ventricular septal defect, tetralogy of Fallot or double outlet right ventricle). Case control study. All animals underwent a comprehensive transthoracic echocardiographic study to document cardiac health or presence of CHD. The vertebral heart score (VHS) was determined in each animal using right lateral survey radiographic images. Blood samples were collected via jugular venipuncture and plasma cTnI concentration and creatine kinase (CK) activity were determined by a 3rd generation immunoassay and an automatic biochemical analyzer, respectively. Groups were compared using Mann-Whitney U-test and receiver-operating characteristics (ROC) curve analysis. Calves with CHD had significantly larger VHS values and higher plasma cTnI concentrations (P < .001) compared to control. Creatine kinase activity was not different between the control and CHD groups of calves. Diagnostic cutoffs of VHS and plasma cTnI for discrimination of groups were 8.9 vertebrae and 0.035 ng/mL, respectively. The cTnI concentration in plasma was significantly correlated with VHS (r (2) =0.512, P < .001). Our results suggest that determination of plasma cTnI concentrations in calves with clinical signs compatible with CHD might prove useful as a guide to quantify cardiac remodeling associated with increased cardiac size.

Effects of feeding whey protein on growth rate and mucosal IgA induction in Japanese Black calves

Data from 63 Japanese Black calves were collected to clarify the effects of feeding whey protein on the growth rate and mucosal IgA induction in calves. Dietary treatments in milk replacers were 1) 26% CP as in skim milk (control), 2) 26% CP as whey and skim milk and 3) 26% CP as whey. Diets were offered from 3 to 63days of age in calves. Feeding whey protein had no effects on growth rate, fecal consistency and fecal water in calves. Compared with 2days of age, fecal IgA concentration in calves decreased at 14days of age, while fecal water increased. Feeding whey protein increased fecal IgA in calves after 14days of age, which was thought to be the increased mucosal IgA induction in the gut. Serum cholesterol concentration tended to be lower in calves fed whey than in control group, but feeding whey protein had no clear effects on serum glucose, NEFA, total protein and urea-N concentrations. These results suggest that feeding whey protein enhances mucosal IgA induction in calves, but feeding whey protein has little effect on growth rate and fecal consistency in calves.

Serum protein concentrations, including acute phase proteins, in calves experimentally infected with Salmonella Dublin

The aim of this study was to evaluate serum protein concentrations in calves experimentally inoculated with Salmonella Dublin. Twelve healthy 10 to 15-day-old Holstein calves were randomly allotted into two groups, control and infected with 10(8) CFU of Salmonella Dublin orally. The calves were subjected to physical evaluation and blood samples were collected shortly before administration of the bacteria and also 24, 48, 72, 96, 120 and 168 hours post-infection. The concentration of serum proteins was determined through sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Thirty serum proteins ranging from molecular weight of 24,000 Da to molecular weight of 236,000 Da were detected. Serum concentrations of ceruloplasmin (125,000 Da), haptoglobin (45,000 Da), acid glycoprotein (40,000 Da) and a 34,000 Da protein were significantly increased in the experimentally infected calves, when compared with their concentrations in the control animals. Therefore, this study showed that S. Dublin infection could lead to the increase of certain serum proteins in calves.

Short communication: Serum immunoglobulin G and total protein concentrations in dairy calves fed a colostrum-replacement product

Neonatal calf health is largely dependent on the ingestion and absorption of maternally derived antibodies via colostrum administration. The objective of this study was to evaluate the efficacy of a commercially available plasma-derived colostrum-replacement (CR) product as compared with bovine colostrum. Holstein calves were removed from the dam immediately after birth and randomly allocated to 1 of 3 groups. Group 1 calves (n=22) were fed 1 package of the CR product; group 2 calves (n=22) were fed 2 packages of the CR product; and group 3 calves (n=22) were fed 3L of bovine colostrum. Blood samples were collected from all calves 24h after colostrum or CR feeding and analyzed for serum IgG and total protein concentrations. Calves fed bovine colostrum had significantly higher serum IgG and total protein concentration than calves in either group fed the CR product. Group 1 calves (1 package of CR product) had a significantly higher incidence of failure of transfer of passive immunity than calves in groups 2 or 3. The results of this study indicated that 2 packages of this CR product achieved adequate IgG concentrations in calves. However, calves fed 1 package of this CR product consistently had failure of transfer of passive immunity.

Hormonal status and regulation of glycemia in neonatal calves during the first hours of postnatal life

The aim of this study was to examine changes in some hormones concentrations in calves during the first 32 hours of neonatal life and to estimate their association with glycemia. Thyrty two Holstein breed calves were selected for the study. Blood samples were taken at 30, 60 and 90 minutes postnatal. Calves received pooled colostrum: primary colostum (1.5 L, 2 hours after birth), secondary colostrum (2 L, 14 hours after birth) and tertiary colostrum (2 L, 26 hours after birth). Blood samples were taken at hours 5, 20 and 32 of neonatal life. Concentrations of glucose, insulin, cortisol, thyroid hormones and IGF-I and abundance of IGFBP-1, IGFBP-2 and IGFBP-3 were determined in the blood serum. The T3/T4 ratio was also calculated. Calves were born hypoglycemic (glycemia was 2.56±1.05 mmol/L at birth). Thereafter, glycemia significantly increased (p<0.001) to 3.05±0.89 mmol/L at min 90. Glucose concentration showed a further increase after colostrum intake and was significantly higher than at the initial value in all examined periods (p<0.001). During the first 90 minutes of neonatal life insulinemia decreased significantly (p<0.001) compared to initial value (26.33±10.05 μIU/L) and it measured 18.66±5.56 μIU/L at min 90. Cortisolemia was highest at minute 30 (85.08±19.36 nmol/L) and than decreased until the end of the experiment (p<0.001) compared to initial values in samples obtained during the period of colostrum intake. A significantly high correlation was determined between glycemia and cortisolemia in all examined periods before the first colostrums intake (r2=0.854; p<0.01 at min 30; r2=0.742; p<0.01 at min 60 and r2=0.551; p<0.01 at min 90). T4 concentrations significantly increased during the first 2 hours, while T3 concentrations decreased, significantly from min 30 to min 90 postnatal (p<0.05). T3/T4 ratio significantly increased during the first 2 hours of neonatal life. After first colostrum intake, concentrations of both hormones rose significantly compared to the initial level, but T3/T4 ratio did not change and maintained the value determined at minute 90. IGF- 1 concentrations significantly decreased during the first 2 postnatal hours. A significant positive correlation was observed between IGF-1 concentration and insulinemia (r2=0.463; p<0.05 at min 30, r2=0.662; p<0.01 at min 60 and r2=0.583; p<0.01 at min 90). IGFBP-3 abundance significantly decreased, while IGFBP-1 significantly increased in this period. IGFBP-2 abundance was highest at birth. Results presented in this study indicate that the increase in glucose concentration during the first 2 hours of neonatal life, before the first colostrum intake is mainly the result of increased activity of the adrenal cortex in cortisol secretion and extrathyroidal tissue thus providing sufficient triiodothyronine. Immaturity of mechanisms responsible for insulin secretion provides the dominance of catabolic processes. Changes of the IGF system provide a rise of glucose concentration and establishment of energy balance.