Metabolic, endocrine and haematological responses to intravenous E. coli endotoxin administration in 1-week-old calves

Relative merits of offering a milk replacer, glucose-electrolyte or whey-based diet on the blood composition and health of unweaned calves after transport

The objective of this randomized controlled trial was to assess the relative merits of offering unweaned calves 3 different types of diets to meet energy and water deficits that can occur during journeys. Six young unweaned male Holstein calves were randomly selected from within 2 body weight ranges (median 48 and 42 kg) from each of 29 loads (total n = 174 calves) transported from an auction market or a collection center to a calf sorting center before transport to a veal unit. The calves were then randomly allocated to one of 3 dietary treatments (n = 58 calves/dietary treatment). They were offered either a milk replacer diet (M), a glucose-electrolyte diet (G) or a whey-based diet with added electrolytes (W). The ability of these diets to provide sufficient nutrient energy to restore vigor, avoid hypoglycaemia and clinical signs of dehydration without increasing the risk of diarrhea was assessed. A clinical assessment of dehydration, health and vigor was made, and the calves were blood sampled before feeding, then 2 h and 4 h after feeding. The plasma glucose concentration was increased 2 h and 4 h after feeding the M and W diets. The increases in plasma glucose concentration were greater 2 and 4 h after (a) feeding the M than after the W diet and (b) feeding the M and W diets than after the G diet. Back-transformed means and 95% Confidence Intervals (CI) for the ratio of the plasma glucose concentration at 4 h compared with 0 h for the milk replacer, glucose-electrolytes and whey-based diets were 1.2 mM CI 1.21, 1.35; 0.95 mM CI 0.92, 0.97; and 1.09 mM CI 1.06, 1.14, respectively. There was no effect of diet on the change in serum total protein concentration between before feeding and 2 and 4 h after feeding. The serum osmolality was lower 2 h after feeding the G diet. The fall in serum osmolality was greater 2 h after feeding the G diet than after feeding the M and W diets. The changes in the serum osmolality between before feeding and 2 h after feeding for the milk replacer, glucose-electrolytes and whey-based diets were -0.68 mosmol CI -3.27, 1.91; -5.23 mosmol CI -7.82, and -2.64; -0.13 mosmol CI -2.77, 2.51, respectively. The diet offered at the sorting center had no effect on subsequent growth on the veal rearing farm between arrival and slaughter (milk replacer 1.22 kg/d, CI 1.17, 1.28; glucose-electrolyte diet 1.23 kg/d. CI 1.18, 1.28; whey-based diet 1.28 kg/d CI 1.23, 1.33). The M diet provided the calves with nutrients and water to replace energy and water deficits that had accumulated before arrival at the sorting center, and these dietary benefits were still apparent 4 h after feeding. The benefits of the W diet were similar to those of the M diet, but the M diet was better able to assist the calves in maintaining their plasma glucose concentration 4 h after feeding than the W diet. The G diet had some short-term benefits in providing energy and assistance to the calves to recover from dehydration, as indicated by a decrease in serum osmolality. However, the G diet was clearly inferior to the M and W diets in providing sufficient energy to assist the calves in recovering from the effects of transport and fasting. During the 4-h after feeding, no adverse effects of offering the calves the M or W diets were observed. The benefits of the W diet in replacing energy and water deficits were similar to those of the M diet, but the M diet was better able to assist the calves in maintaining their blood glucose concentration 4 h after feeding than the W diet.

Additive prognostic value of preoperative plasma glucose concentrations in calves undergoing abdominal surgery

Surgical abdominal emergencies in calves are associated with a guarded prognosis, especially if neonates are affected. Because hypoglycemia has been associated with sepsis and endotoxemia, this study aimed to assess the prognostic relevance of preoperative plasma glucose concentrations (GLUC) in calves requiring surgery for an acute abdominal disorder. For this purpose, data from retrospective and prospective case series were analyzed, consisting of 586 and 83 hospitalized calves, respectively. The outcomes of calves were evaluated until hospital discharge (both study populations) and for 3 mo following discharge by a phone call to the farmer (prospective study population). For the retrospective study population, the overall survival rate was 31.2%. Calves with a negative outcome (NO) had significantly lower median GLUC (4.3 mmol/L) than calves with a positive outcome (PO; 5.0 mmol/L). The survival rates of calves with GLUC <2.4 mmol/L and 2.4 to 3.1 mmol/L were 3.6 and 8.3%, respectively. The inclusion of GLUC improved a previous prognostic model based on plasma l-lactate concentration and age. The resulting analyses indicated that NO was associated with low age (<7 d), hyper-l-lactatemia (>8.84 mmol/L), and GLUC <4.4 mmol/L (age 7-20 d) and <3.3 mmol/L (age ≥21 d), respectively. The area under the receiver operating characteristic curve of this model was 0.79 (95% confidence interval: 0.76-0.83) and the resulting sensitivity and specificity for NO at the optimal probability cut-point of 0.69 were 66.7 and 85.8%, respectively. For the prospective study population, the established model had sensitivity and specificity for predicting NO after 3 mo (proportion 24%) of 61.9 and 85%, respectively. In both study populations, hypoglycemia was significantly associated with intraoperative evidence of a septic process within the abdominal cavity. The present analyses show that hypoglycemia was highly indicative of a poor prognosis and serious intraoperative findings such as peritonitis. Determination of GLUC should therefore be part of the diagnostic work-up in calves suffering from an acute abdominal emergency.

Effect of nanocurcumin and fish oil as natural anti-inflammatory compounds vs. glucocorticoids in a lipopolysaccharide inflammation model on Holstein calves' health status

Curcumin (CUR) and fish oil (FO) are among the most well-known types of natural anti-inflammatory compounds. The aim of this study was to assess the effect of nanocurcumin and fish oil vs. glucocorticoids on Holstein calves’ health status. A lipopolysaccharide (LPS) challenge (0.5 μg kg⁻¹ BW) was used to induce an acute phase response. A total of 42 male Holstein calves were randomized into 7 groups: negative control (CON), positive control (LPS, injected once), 250 mg/kg BW per day fish oil + LPS (FO250), 350 mg/kg BW per day fish oil + LPS (FO350), 2 mg/kg BW per day nanocurcumin + LPS (NCUR2), 4 mg/kg BW per day nanocurcumin + LPS (NCUR4), and 0.3 mg/kg BW dexamethasone (injected once) + LPS (DEX). The duration of this experiment was 11 days, with application of the LPS challenge on day 8. Calves were weighed on days 0, 7, 9, 10, and 11 to record the average daily weight gain; diets offered and refused were recorded daily throughout the experiment. Blood collection and clinical scoring were conducted at successive time points until 72 h post LPS challenge. The data obtained also comprised rectal temperature (RT), respiratory rate (RR), heart rate (HR), concentrations of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), serum amyloid A (SAA), and haptoglobin (Hp). This experiment could not uncover significant effects of LPS, FO, NCUR, and DEX on the area under the curve (AUC) of the RT, HR, and RR; in addition, there was no difference between FO and NCUR vs. LPS in sickness behavior, however, DEX group significantly recovered faster than others (P < 0.01). There was no significant difference between groups in dry matter intake (DMI) and average daily gain (ADG) during three days post LPS challenge. The concentrations of TNF-⍺, IL-6, and SAA were lower in the DEX group (P < 0.05). Finally, no effects of FO and NCUR on cytokines and acute phase proteins (APPs) could be observed in this study. In conclusion, supplementation of FO and NCUR was not able to impact the acute phase response (APR) in calves, as levels of inflammatory cytokines and APPs as well as sickness behavior remained unchanged. It seems that the anti-inflammatory effects of FO and CUR on APR, as has been observed for other animal species, do not manifest that clearly in calves.

The effects of feeding high or low milk levels in early life on growth performance, fecal microbial count and metabolic and inflammatory status of Holstein female calves

Gut microbial colonization and immune response may be affected by milk feeding method. The objective of this study was to determine the effects of feeding high or low volumes of milk on fecal bacterial count, inflammatory response, blood metabolites and growth performance of Holstein female calves. Colostrum-fed calves (n = 48) were randomly assigned to either high milk (HM; n = 24) or low milk (LM; n = 24) feeding groups. Low milk-fed calves were fed pasteurized whole milk at 10% of BW until weaning. In HM group, milk was offered to calves at 20% of BW for the first 3 weeks of life. Then, milk allowance was decreased gradually to reach 10% of BW on day 26 and remained constant until weaning on day 51. Calves were allowed free access to water and starter throughout the experiment. Body weight was measured weekly, and blood samples were taken on days 14, 28 and 57. Fecal samples were collected on days 7, 14 and 21 of age for the measurement of selected microbial species. By design, HM calves consumed more nutrients from milk during the first 3 weeks and they were heavier than LM calves on days 21, 56 and 98. High milk-fed calves had greater serum glucose and triglyceride levels on day 14 with no significant difference between groups on days 28 and 57. Blood urea nitrogen was higher in LM calves on day 14, but it was lower in HM calves on day 28. Calves in LM group had significantly greater blood tumor necrosis factor-α (TNF-α) than HM calves throughout the experiment. Serum amyloid A (SAA) concentration was higher in LM calves on day 14. However, HM calves showed higher levels of SAA at the time of weaning. Feeding high volumes of milk resulted in lower serum cortisol levels on days 14 and 28 but not at the time of weaning in HM calves compared to LM counterparts. Lactobacillus count was higher in feces sample of HM calves. Conversely, the numbers of Escherichia coli was greater in the feces of LM calves. Calves in HM group showed fewer days with fever and tended to have fewer days treated compared to LM group. In conclusion, feeding higher amounts of milk during the first 3 weeks of life improved gut microbiota, inflammation and health status and growth performance of Holstein dairy calves.

Pharmacokinetics of ceftiofur in healthy and lipopolysaccharide-induced endotoxemic newborn calves treated with single and combined therapy

The aim of this research was to compare plasma pharmacokinetics of ceftiofur sodium (CS) in healthy calves, and in calves with experimentally induced endotoxemia. Six calves received CS (2.2 mg/kg, IM) 2 hr after intravenous administration of 0.9% NaCl (Ceft group). After a washout period, the same 6 calves received CS 2 hr after intravenous injection of lipopolysaccharide (LPS+Ceft group). Another group of 6 calves received a combination of drug therapies that included CS 2 hr after administration of 0.9% NaCl (Comb group). A third group of 6 calves received the same combination therapy regimen 2 hr after intravenous injection of lipopolysaccharide (LPS+Comb group). Plasma concentrations of CS and all desfuroylceftiofur-related metabolites were determined using HPLC, and its pharmacokinetic properties were determined based on a two-compartment model. The peak concentration of CS in the LPS+Comb group occurred the earliest, and the clearance rate of CS was the highest in the Comb and LPS+Comb groups (P<0.05). The elimination half-life of CS in the LPS+Ceft group was longer than that in the Ceft and Comb groups (P<0.05). The results of this study indicate that combined therapies and endotoxemic status may alter the plasma pharmacokinetics of CS in calves.

Hypoglycaemia in hospitalised neonatal calves: Prevalence, associated conditions and impact on prognosis

Hypoglycaemia has traditionally been associated with neonatal diarrhoea and endotoxaemia in calves, but the clinical relevance of this finding in spontaneously diseased calves has not previously been evaluated. To determine the prevalence and prognostic relevance of severe hypoglycaemia (plasma glucose concentration < 2 mmol/L), data from 10,060 hospitalised calves (≤21 days of age) were retrospectively analysed. Additionally, clinical findings and diagnoses in a subset of 100 calves with severe hypoglycaemia were compared with those in 100 randomly selected calves with initial plasma glucose concentrations in the reference range (4.4-6.9 mmol/L). The prevalence of severe hypoglycaemia in the whole study sample was 6.3%. Severe hypoglycaemia was associated with a poor survival rate of 20.6% vs. 74.0% discharged animals in the group of calves with initial normoglycaemia. Review of medical records revealed that severe hypoglycaemia was significantly associated with clinical or necropsy evidence of septicaemia, hypothermia, history or clinical evidence of malnutrition, and peritonitis of varied origin, but not with the presence of neonatal diarrhoea. Only 10 of 100 calves with severe hypoglycaemia showed central nervous involvement such as seizures and opisthotonus. In conclusion, severe hypoglycaemia has a low prevalence in diseased calves in a hospital setting, but is associated with serious health problems and therefore a high risk of non-survival. Severe hypoglycaemia was not easily diagnosed based on clinical signs, but should be suspected in calves with clinical evidence of septicaemia, hypothermia, acute abdominal emergencies, and a history or clinical evidence of malnutrition.

Characterization of the contributions of Hp-MMP 9 to the serum acute phase protein response of lipopolysaccharide challenged calves

Background

Bovine respiratory disease (BRD) is a costly feature of modern cattle production. Early and accurate detection of BRD may prove useful in the successful management of this disease. The primary objective of the study was to define the time course of covalent complexes of neutrophil, haptoglobin (Hp) and matrix metalloproteinase 9 (Hp-MMP 9) in serum after intravenous lipopolysaccharide (LPS) in comparison to traditional markers. Our hypothesis was that serum concentrations of neutrophil Hp-MMP 9 provides information distinct from traditional acute phase protein markers. To characterize the neutrophil responses to lipopolysaccharide (E. coli; O111:B4; 2.5 μg/kg body weight), nine healthy, Jersey calves (65-82 days of age; 74.5 ± 13.1 kg) were challenged and physiologic parameters, peripheral blood cell counts and serum cortisol (C), Hp-MMP 9, Hp, alpha₁-acid glycoprotein (AGP), serum amyloid A (SAA) were obtained starting 24 hours before to 96 hours post-LPS challenge.

Results

Physiologic parameters (temperature, pulse, respiratory rate) and attitude assessed at each time point indicated that LPS challenge resulted in rapid onset of depression, tachypnea, leukopenia, neutropenia and lymphopenia within 1 hour. Serum C concentrations were significantly increased by 1 hour post-LPS. Serum Hp-MMP 9 complexes were detectable in serum by 0.5 hours and peaked at 16 h, serum total Hp remained <10 μg/mL until 8 hours post LPS infusion and were significantly greater than baseline by 12 hours post-LPS infusion. Serum amyloid A concentrations increased significantly by 8 hours post LPS. Serum concentrations of AGP increased significantly by 16 hours post LPS. Serum concentrations of Hp, SAA and AGP remained significantly greater than baseline out to 96 hours post-LPS. The total systemic exposure to traditional makers is significantly greater than from Hp-MMP 9

Conclusion

Using a well described model for acute phase protein responses, the data demonstrate that serum neutrophil Hp-MMP 9 complexes appear sooner and decline more rapidly than other acute phase proteins (APP). Since Hp-MMP9 is stored pre-formed, it provides information specifically addressing the LPS-induced activation of bovine neutrophils. Contributions of Hp-MMP 9 to the serum acute phase protein response may provide useful information, independent of hepatic responses, in diagnosis of acute inflammation.

Effects of intravenous Escherichia coli dose on the pathophysiological response of colostrum-fed Jersey calves

Objectives of the present study were to characterize the dose dependency of an intravenous Escherichia coli O111:H8 challenge in colostrum-fed Jersey calves and to identify any biochemical markers indicative of septicemia. Eighteen 3-week old colostrum-fed Jersey calves were completely randomized to 1 of 6 doses of E. coli O111:H8. The challenge doses included 0, 1.5 × 10⁵, 1.5 × 10⁶, 1.5 × 10⁷, 1.5 × 10⁸, and 1.5 × 10⁹ colony-forming units (CFU) given intravenously as a bolus in 5 mL of sterile isotonic saline. Peripheral blood samples were collected at 0, 2, 4, 8, 12, 24, and 48 h relative to the challenge for biochemical, total leukocyte count, and differential analyses. Rectal temperatures were collected via indwelling rectal temperature probes at 5-min intervals, and hourly averages calculated from 2 d prior to the challenge till 2 d after the challenge. All calves survived the 48 h observation period following the challenge. Calves given 1.5 × 10⁸ and 1.5 × 10⁹ CFU displayed sickness behaviors (P < 0.01) beginning 0.5 h after the challenge and returned to that of the control calves by 6 and 32 h for calves challenged with 1.5 × 10⁸ and 1.5 × 10⁹ CFU, respectively. There were treatment × time interactions (P < 0.01) on total leukocyte counts and plasma glucose and zinc concentrations. Calves administered 1.5 × 10⁸ and 1.5 × 10⁹ CFU had leucopenia beginning 2 h after the challenge and returning to counts similar to the control calves within 24 h. Additionally, those calves were hypoglycemic from 4 to 12 h after the challenge with the degree of hypoglycemia inversely related to the dose of the E. coli. All calves challenged with E. coli had decreased plasma zinc concentrations, and the magnitude was inversely proportional to the challenge dose. There were treatment × time interactions (P < 0.001) on rectal temperatures following the challenge. All calves challenged with E. coli developed a febrile response, but the intensity and duration of the response were dependent on the challenge dose. These data indicate that calves intravenously challenged with 1.5 × 10⁸ and 1.5 × 10⁹ CFU of the E. coli O111:H8 showed immediate clinical and biochemical signs indicative of septicemia. However, calves administered 1.5 × 10⁷ or less of the E. coli had febrile responses, but did not develop septicemia. Blood glucose and zinc concentrations may be dose responsive indicators that could potentially differentiate between a septicemic versus non-septicemic calf.

Effects of intravenous infusion of lipopolysaccharide on plasma micromineral, magnesium, and cytokine concentrations and serum cortisol concentrations in lactating goats

OBJECTIVE

To assess the effects of various doses of lipopolysaccharide (LPS) administered IV on plasma microminerals, magnesium, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 concentrations and serum cortisol concentrations in lactating goats.

ANIMALS

6 lactating goats.

PROCEDURES

Goats were allotted to 3 LPS-treatment groups: control (0 microg/kg), low LPS (10 microg/kg), and high LPS (50 microg/kg). Rectal temperatures and behaviors of goats were recorded immediately before a 10-minute IV infusion of LPS and at 0.5, 1, 2, 4, 6, 8, and 24 hours after infusion. Blood samples were obtained before IV infusion and at 0.5, 1, 2, 4, 6, 8, and 24 hours after infusion. Plasma zinc, copper, iron, and magnesium concentrations were determined by atomic absorption spectrometry; plasma TNF-alpha and IL-6 concentrations were measured by use of an ELISA; and serum cortisol concentrations were determined by use of a radioimmunoassay.

RESULTS

A monophasic fever developed in low-LPS and high-LPS groups. In the low-LPS and high-LPS group, plasma zinc concentrations decreased at 6 hours after infusion; compared with control groups. Plasma iron concentrations were lower at 24 hours after infusion in low-LPS and high-LPS groups than in the control group. Plasma TNF-alpha and IL-6 concentrations were higher in low-LPS and high-LPS groups than in the control group at 1, 2, and 4 hours after infusion. In low-LPS and high-LPS groups, serum cortisol concentrations increased from 0.5 hours onward and peaked at 1 (high-LPS group) and 2 (low-LPS group) hours after infusion.

CONCLUSIONS AND CLINICAL RELEVANCE

Following IV infusion of LPS, the immune system is activated, which might affect micromineral homeostatic regulation and, subsequently, the metabolic health of lactating goats.

Long-term feed intake regulation in sheep is mediated by opioid receptors

These experiments were conducted to determine if 1) syndyphalin-33 (SD33), a mu-opioid receptor ligand, affects feed intake; 2) SD33 effects on feed intake are mediated by actions on opioid receptors; and 3) its activity can counteract the reduction in feed intake associated with administration of bacterial endotoxin. In Exp. 1, 5 mixed-breed, castrate male sheep were housed indoors in individual pens. Animals had ad libitum access to water and concentrate feed. Saline (SAL; 0.9% NaCl) or SD33 (0.05 or 0.1 micromol/kg of BW) was injected i.v., and feed intake was determined at 2, 4, 6, 8, 24, and 48 h after the i.v. injections. Both doses of SD33 increased (at least P < 0.01) feed intake at 48 h relative to saline. In Exp. 2, SAL + SAL, SAL + SD33 (0.1 micromol/kg of BW), naloxone (NAL; 1 mg/kg of BW) + SAL, and NAL + SD33 were injected i.v. Food intake was determined as in Exp. 1. The SAL + SD33 treatment increased (P = 0.022) feed intake at 48 h relative to SAL + SAL. The NAL + SAL treatment reduced (at least P < 0.01) feed intake at 4, 6, 8, 24, and 48 h, whereas the combination of NAL and SD33 did not reduce feed intake at 24 (P = 0.969) or 48 h (P = 0.076) relative to the saline-treated sheep. In Exp. 3, sheep received 1 of 4 treatments: SAL + SAL, SAL + 0.1 micromol of SD33/kg of BW, 0.1 microg of lipopolysaccharide (LPS)/kg of BW + SAL, or LPS + SD33, and feed intake was monitored as in Exp. 1. Lipopolysaccharide suppressed cumulative feed intake for 48 h (P < 0.01) relative to saline control, but SD33 failed to reverse the reduction in feed intake during this period. These data indicate that SD33 increases feed intake in sheep after i.v. injection, and its effects are mediated via opioid receptors. However, the LPS-induced suppression in feed intake cannot be overcome by the opioid receptor ligand, SD33.

Characterization of calves exhibiting a novel inheritable TNF-α hyperresponsiveness to endotoxin: associations with increased pathophysiological complications

A subpopulation of calves, herein termed “hyperresponders” (HPR), was identified and defined by the patterns of plasma TNF-α concentrations that developed following two challenges with endotoxin (LPS, 0.8 μg Escherichia coli 055:B5 LPS/kg0.75live body wt) separated by 5 days. The principle characteristic of HPR calves was a failure to develop tolerance to repeated LPS challenge that was evident in the magnitude of the TNF-α concentrations and prolonged severity of pathological sequellae. Whereas calves failing to develop LPS tolerance were identified on the basis of their excessive in vivo plasma TNF-α concentration responses, in vitro TNF-α responses of peripheral blood mononuclear cells isolated from each calf and challenged with LPS or PMA did not correlate or predict the magnitude of in vivo plasma TNF response of the calf. Intentional breeding to obtain calves from bulls and/or cows documented as HPR resulted in offspring displaying the HPR character when similar progeny calves were tested with LPS in vivo, with extensive controls in place to account for sources of variability in the general TNF-α response to LPS that might compromise interpretation of the data. Feed intake, clinical serology and hematology profiles, and acute-phase protein responses of HPR calves following LPS were significantly different from those of calves displaying tolerance. These results suggest that the pattern of plasma TNF-α changes that evolve from a low-level double LPS challenge effectively reveal the presence of a genetic potential for animals to display excessive or prolonged pathological response to LPS-related stress and compromised prognosis for recovery.

Efficacy of an Escherichia coli J-5 mutant strain bacterin in the protection of calves from endotoxin disease caused by subcutaneous challenge with endotoxins from Escherichia coli

The purpose of this trial was to examine the potential of a new Escherichia (E) coli J-5 mutant strain bacterin to reduce the severity of clinical disease caused by subcutaneous challenge with endotoxins of Gram-negative bacteria in calves. Day-old to 3-day old calves (n = 40 per study phase) were randomly assigned to either of two treatment groups, i.e. a vaccinated or a placebo group. Calves in the vaccinated group received an inactivated bacterin containing a J-5 mutant strain of E. coli via subcutaneous route at 2-4 days of age and at 14 days thereafter. The placebo contained only adjuvant and saline in lieu of the antigen. Lipopolysaccharides (LPS) originating from E. coli were administered subcutaneously 3 weeks after the booster dose. The LPS challenge dosages were 1 and 8 microg/kg in study phases I and II, respectively. Various clinical, physiological, hematological, and serological parameters were measured at specific time intervals after challenge. The data were mostly analysed using peak changes from baseline recorded during the observation period. By the time of challenge the titers in vaccinated calves had increased significantly more than in the unvaccinated controls. Disease severity following subcutaneous challenge was dose dependent. In phase I, placebo calves were only mildly challenged whereas in phase II placebo calves showed a moderate challenge. After a mild challenge, there was little evidence of protection due to vaccination as only attitude was significantly improved in the vaccinates. In contrast, after a moderate challenge rectal temperature, hematocrit, blood glucose concentrations, and leukocyte changes were significantly better in the vaccinated group. In conclusion, the results of this study show that following a subcutaneous endotoxin challenge that induces a moderate clinical response, calves that were previously vaccinated with the E. coli J-5 bacterin were better protected than those in the placebo group.

An explorative study to assess the efficacy of toltrazuril-sulfone (ponazuril) in calves experimentally infected with Neospora caninum

BACKGROUND

Neospora caninum is an important cause of infectious abortion and stillbirth in cattle world-wide. Infection is common and may frequently be passed from mother to calf (vertical transmission) with no signs of disease. Based on our previous observation that N. caninum-infection can be efficiently controlled with toltrazuril-sulfone (ponazuril) in experimentally infected mice, we addressed the question if efficacy could also be obtained in experimentally infected calves.

MATERIAL AND METHODS

The study included 19 calves and represents an initial explorative approach to document a basic effectiveness at first. Fifteen animals received each 2 x 10(8) N. caninum trophozoites, half of the dose being injected intravenously and the other half subcutaneously. Efficacy of treatment was assessed using molecular detection of parasite DNA with PCR and pathological alterations by immunohistochemistry in different organs of the animals. Assessment included also clinical, serological and pathophysiological parameters.

RESULTS

In those calves medicated with ponazuril (one, or six consecutive days, respectively, starting one day after infection), a complete abrogation of the parasite detectability was obtained in the brain and other organs, while 50% of non-treated calves became PCR-positive in brain and muscles. Clinically, ponazuril chemotherapy of infected calves--in comparison to non-treated infected animals--reduced symptoms (fever), but no differences were observed between treated and non-treated animals with regard to serum enzymes and metabolites. Efficacy of a six-day treatment was also reflected by significantly lower anti-Neospora antibody concentrations developed after infection, when compared to non-treated animals.

CONCLUSION

Based on our findings in this initially explorative approach that indicate a basic effectiveness of ponazuril against experimental N. caninum infection in calves, we plan to follow our chemotherapeutical intervention strategy to control bovine neosporosis with a subsequent more extensive field study with naturally infected calves.

Metabolic and endocrine changes in response to endotoxin administration with or without oral arginine supplementation

This study was performed to investigate blood metabolite, tumor necrosis factor-alpha, and hormone responses to intravenous administration of lipopolysaccharides (2 microg of endotoxin of Escherichia coli 026:B6/kg body weight at times of feeding) in veal calves orally supplemented with arginine (0.25 g/kg of body weight twice daily for 4 d; group GrA) compared with calves not supplemented with arginine (group GrC). Arginine supplementation alone caused a significant rise of plasma arginine, urea, and insulin concentrations, whereas glucagon concentrations tended to increase, but there were no significant group differences. Concentrations of triglycerides, NEFA, glucose, protein, albumin, growth hormone, insulin-like growth factor-I, 3.5.3'-triiodothyronine, and thyroxine were not affected by arginine supplementation. Lipopolysaccharide administration alone caused a rise of tumor necrosis-factor-a, lactate, and cortisol concentrations and concentrations of tumor necrosis-factor-a after 1 h, and of triglycerides and urea after 6 h were higher, whereas of glucose after 3 h were lower in GrA than in GrC. Concentrations of NEFA, glucose, protein, albumin, insulin, growth hormone, insulin-like growth factor-I, 3.5.3'-triiodothyronine, and thyroxine were not affected by lipopolysaccharide administration. In conclusion, arginine supplementation had selective effects on plasma metabolites and hormones, but barely modified lipopolysaccharide effects. Effects of lipopolysaccharides in the postprandial state were different from what is usually seen in the fasted state.

Nitrite/Nitrate responses to endotoxin in calves

Plasma concentrations and urinary excretions of nitrite plus nitrate (NOx) increase in heifers after endotoxin-induced nitric oxide synthase activation. The rise can be enhanced by administration of arginine, the substrate for the production of nitric oxide, whose effects may be modified by the iron status. In 10-week-old veal calves (six Simmental x Red Holstein) arginine (0.5 g/kg body weight for 6 h) was intravenously infused. At 2 h after the start of the infusions Escherichia coli endotoxin O26:B6 (2 microg/kg body weight) was intravenously injected. This caused a rise of rectal temperature, heart rate, respiration rate, and of urinary NOx excretion, but not of plasma NOx concentrations, in contrast to the experience with older cattle to which the same amounts of arginine were infused before and during endotoxin administration. In 8-week-old veal calves (18 Simmental x Red Holstein) the question of whether oral supplementation with arginine and iron modifies NOx responses to endotoxin (2 microg/kg) was also investigated. The calves were divided between three groups (GrA-, GirA+, GrC) and before endotoxin injections GrA- was fed 0.5 g arginine/kg for 4 days, GrA+ was fed 0.5 g arginine/kg for 4 days plus 80 mg iron/kg milk for 2 weeks, whereas GrC was not supplemented with arginine or iron. Iron supplementation increased plasma iron concentrations and arginine supplementation increased plasma arginine and urea concentrations and urinary urea excretion. Ensuing administration of endotoxin enhanced plasma tumour necrosis factor-alpha concentrations, rectal temperature, heart rate, and respiration rate, but not plasma NOx concentrations in GrC and GrA- and only transiently and slightly increased plasma NOx concentrations in GrA+ but did not affect urinary NOx excretions. In conclusion, the expected stimulation of NOx responses to endotoxin by intravenous arginine infusion appears to be much weaker in young veal calves than in older cattle. The NOx responses in young veal calves were not modified if arginine was orally administered and plasma NOx were barely enhanced by combined oral supplementation of arginine and iron.

Tumor necrosis factor-alpha and nitrite/nitrate responses during acute mastitis induced by Escherichia coli infection and endotoxin in dairy cows

Concentrations of tumor necrosis factor-alpha (TNF-alpha) and of NO(x) (sum of nitrite and nitrate as indicators of endogenous nitric oxide production) in milk and blood plasma were measured in three mastitis models in dairy cows in early lactation. Escherichia coli P4:O37 bacteria or endotoxin O111:B4 were administered into both left quarters of 12 and 6 cows, respectively. Six of the E. coli-infected cows were treated with a bactericidal antibiotic (Enrofloxacin; Bayer AG, Leverkusen, Germany) i.v. at 10 hr and subcutaneously (sc) at 30 hr after infection. NO(x) concentrations transiently increased maximally 10- to 11-fold in milk of E. coli-infected quarters with or without antibiotic treatment at 24 hr and after endotoxin administration. NO(x) concentrations did not change in milk of unchallenged quarters and in blood plasma. Increases of NO(x) were proceeded by a transient (96- to 149-fold) rise of milk TNF-alpha concentrations, which in endotoxin-administered quarters was maximal at 6 hr and in infected quarters without or with Enrofloxacin treatment at 10 and 14 hr. In blood plasma TNF-alpha concentrations only moderately increased to peaks in endotoxin-administered cows at 6 hr and in E. coli-infected cows at 14 hr postchallenge. In one severely sick, nontreated E. coli-infected cow milk, TNF-alpha response at 14 hr was excessive and followed by a spectacular rise of NO(x) concentration in milk between 48 and 72 hr. In conclusion, a possible clinical relevance of nitric oxide production associated with a rise of intramammary and systemic TNF-alpha during acute mastitis by E. coli infection and endotoxin in lactating dairy cows is indicated, but could not be inhibited by antibiotic treatment.

Alterations of growth hormone, cortisol, luteinizing hormone, and insulin concentrations in early-postnatal calves affected with diarrhea

The aim of the study was to investigate the influence of diarrheic infections during the early postnatal phase of calves on the concentrations of hormones controlling reproduction and metabolism. Blood samples were collected from 20 male and female calves via jugular vein catheters every 15 min for 6 hr at Days 3, 9, and 21 of life. The animals were classified into three groups. Group 1 (controls): healthy calves (n = 9). Group 2: calves affected with diarrhea at Day 9 (n = 7). Group 3: calves with diarrhea at Days 3 and 9 (n = 4). Infections occurred spontaneously and were mainly due to E. coli infections. All affected calves had recovered at Day 21. Mean GH concentrations in the calves in Groups 2 and 3 compared to control calves had increased by Day 3 (P<0.01; P<0.001). Cortisol levels of calves in all groups were highest at Day 3 and decreased thereafter (P<0.001). Cortisol concentrations were lower at Day 3 in animals in Groups 2 (P<0.001) and 3 (P<0.05) than in controls. Pulsatile LH release was detectable at Days 9 and 21 only in healthy calves. Insulin increased at Day 9 during diarrhea. The results indicate that cortisol concentrations decreased whereas GH concentrations were increased before diarrhea was observed. The onset of pulsatile LH release was delayed in diarrheic calves. It is concluded that diarrhea exerts effects upon the release of reproductive and metabolic hormones in early postnatal calves.

Effect of endotoxin challenge on hepatic 5'-deiodinase activity in cattle

Thyroid status is compromised in a variety of acute and chronic infections and toxin-mediated disease states. Conversion of thyroxine (T4) into the metabolically active hormone, triiodothyronine (T3), is catalyzed by 5'-deiodinase (5'D). Our objective was to determine the effect of endotoxin (LPS) challenge with and without L-arginine (Arg) infusion on hepatic activity of 5'D and plasma concentrations of T4 and T3. In a 2 x 2 factorial, beef heifers (275-310 kg b.wt.) were fed low (8% CP; 6.5 kg/d) or high (14% CP; 7.2 kg/d) isocaloric protein diets (1.96 Mcal/kg DM) for 10 d before LPS challenge. L-Arginine in saline (0.5 g/kg b.wt.) or saline alone was infused i.v. throughout an 8 hr period starting 2 hr before bolus LPS injection (Escherichia coli, 055: B5; 0.2 microg/kg; i.v.). Blood samples were collected at -2, 0, 3, 6, 12, and 24 hr relative to LPS injection. Liver samples were obtained 20 hr before, and then 6 and 24 hr after LPS challenge using a biopsy needle. Plasma T4 and T3 concentrations were not affected by dietary CP or Arg. Compared with levels at 0 hr, LPS challenge decreased plasma T4 (P < 0.01) and T3 (P < 0.001), respectively, 8.4% and 28.9% at 6 hr and 19.7% and 31.3% at 24 hr. Consistent with these changes, the T3:T4 ratio was lower than that at 0 hr (P < 0.001) 22.0% at 6 hr and 13.5% at 24 hr. Hepatic 5'D activities 20 hr before LPS injection were 2.80 +/- 0.11 nmol I- x hr(-1) x mg protein(-1) and decreased 24 hr after LPS, respectively, 45.4% (P < 0.01) and 17.6% (P < 0.05) in saline- and Arg-infused heifers. The results indicate that mild LPS challenge in cattle inhibits hepatic generation of T3 and decreases plasma concentrations of thyroid hormones. The data also suggest that the impact of LPS on 5'D activity in liver can be altered by Arg supplementation.

Clinical, haematological, metabolic and endocrine traits during the first three months of life of suckling simmentaler calves held in a cow-calf operation

Newborn suckling Simmentaler calves (10 males and 9 females) in a cow-calf operation were examined from birth up to the age of 3 months. The average daily gain from 47 to 120 kg was 0.86 kg. Except for higher average daily weight gains and insulin-like growth factor-I concentrations and lower thyroid hormone levels in male than female calves, there were no significant sex differences. Plasma glucose, total protein and immunoglobulin G concentrations increased on day 1 of life, thrombocyte number and plasma triglyceride concentrations rose during the first 7 days, whereas lymphocyte and monocyte percentage and plasma inorganic phosphorus, phospholipid, cholesterol and albumin concentrations increased during the first 14 or 21 days and then remained elevated. Eosinophil percentage increased after 3 weeks and insulin-like growth factor-I concentrations increased over the whole growth period. There were transient elevations of plasma glucagon concentrations up to day 14, of the activity of alkaline phosphatase transiently up to day 7 and of gamma-glutamyltransferase, aspartate aminotransferase and lactate dehydrogenase activities on day 1 of life. Plasma iron concentration transiently decreased up to day 28 and creatine kinase activity up to day 7. Total white blood cell number, neutrophil percentage, packed cell volume and concentrations of haemoglobin, calcium, magnesium (after a transient rise on day 1), non-esterified fatty acids, bilirubin, creatinine, triiodothyronine and thyroxine decreased from birth up to days 42, 56, 28, 28, 21, 84, 14, 14, 7, 14 and 7, respectively. Basophil percentage and concentrations of beta-hydroxybutyrate, urea and insulin did not exhibit significant age-dependent changes. The behaviour of most traits in the first weeks was the same in suckling calves under study as in non-suckling pre-ruminant calves. However, packed cell volume, red blood cell number, haemoglobin and plasma iron concentrations were higher, whereas glucose and insulin concentrations were lower than normally found in veal calves. On the other hand, concentrations of glucose, insulin and insulin-like growth factor-I in suckling calves in the third month of age were higher than can normally be measured in breeding calves.

Blood metabolites and hormones--especially glucose and insulin--in veal calves: effects of age and nutrition

Veal calves often develop insulin resistance, hyperglycaemia and glucosuria. We have studied effects of age and nutrition on blood metabolites and hormones, with major emphasis on glucose and insulin, in four groups of veal calves from 66-69 kg until slaughter at 175-196 kg. Calves were fed milk replacers which differed with respect to lactose, total sugar, protein and fat content. Mean intakes in groups 1, 2, 3 and 4 of lactose (1.24, 1.08, 0.95 and 0.66 kg/d), total sugar (1.27, 1.10, 1.01 and 96 kg/d), crude protein (0.40, 0.48, 0.65 and 0.49 kg/d) and crude fat (0.32, 0.31, 0.37 and 0.46 kg/d) were different. Average daily gains were 1.46-1.49 kg and feed/gain ratios were 1.49-1.61 kg/kg. Glucose and insulin concentrations were not associated with protein and fat intakes, but followed lactose and total sugar intakes, albeit differently at the start and end of the growth trial. Thus, insulin concentrations were higher (P < 0.05) at the end than at start of the growth trial in all 4 groups, whereas glucose concentrations increased (P < 0.05) with increasing age in only group 2. In conclusion, lactose and total sugar intakes affected the degree of hyperglycaemia and modified hyperinsulinemia at a given age, but the age-dependent rise of insulin concentrations could not be explained by hyperglycaemia alone.

Changes of blood metabolites and hormones in breeding calves associated with weaning

Changes of blood metabolites and hormones were studied in female breeding calves before, during and after weaning from 4 to 18 weeks of age. Calves were initially fed increasing amounts of whole milk (up to 7 kg/day in week 8 of life). Milk intake was then gradually decreased up to the age of 16 weeks, when calves were completely weaned and only fed hay and concentrates. Average daily gain was 0.85 kg. Postprandial concentrations of glucose, insulin, insulin-like growth factor-I and 3.5.3'-triiodothyronine concentrations gradually decreased (P < 0.05) with age, while those of beta-hydroxybutyrate, protein, albumin, haemoglobin and iron increased (P < 0.05). Concentrations of cholesterol transiently increased, whereas those of urea reversibly decreased. Non-esterified fatty acids, triglycerides and growth hormone did not consistently change during the duration of the study. In conclusion, changes of glucose, beta-hydroxybutyrate, haemoglobin, iron, insulin, insulin-like growth factor-I and 3.5.3'-triiodothyronine were markedly different from those usually seen in veal calves of the same age.

Characterisation of the acute phase response of heifers to a prolonged low dose infusion of lipopolysaccharide

The effect of a prolonged low dose infusion of bacterial lipopolysaccharide (LPS) on acute phase-like reactions was examined in heifers. LPS (2 micrograms kg-1 dissolved in 100 ml water), or saline was infused (at 1 ml min-1) intravenously for 100 minutes and blood samples were taken at various times before, during and after the infusion. The serum concentrations of tumour necrosis factor-alpha (TNF alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and serum amyloid A (SAA) and the rectal temperature increased in response to the LPS infusion. Serum TNF alpha increased before the increases in IL-1 beta and IL-6 and remained high from 20 minutes after the onset of the infusion until the end of the sampling period (six hours). The LPS-induced increases in serum IL-1 beta and IL-6 were biphasic. Plasma cortisol and lactate concentrations also increased, and plasma glucose and beta-hydroxybutyrate concentrations decreased in response to the LPS infusion. The similarity of these reactions to changes observed in response to bacterial infections shows that the prolonged infusion of low doses of LPS is a good model for studying the acute phase response to Gram-negative bacterial infection in heifers.