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1.
The objective was to compare the mRNA expression of pro-inflammatory (TNF-α, IL-1β, IFN-γ, IL-2, IL-12, IL-15) and anti-inflammatory (IL-4, IL-10, TGF-β) cytokines, after experimental infection with low or high virulence noncytopathic (ncp) bovine viral diarrhea virus (BVDV). Thirty BVDV-naïve, beef calves were intranasally inoculated with low (LV; n = 10, SD-1) or high (HV; n = 10, 1373) virulence ncp BVDV or with BVDV-free cell culture medium (Control, n = 10). Calves were euthanized on day 5 post-inoculation, and tracheo-bronchial lymph node and spleen samples were collected for mRNA expression through quantitative-RT-PCR. mRNA levels of pro-inflammatory (TNF-α, IL-1β, IL-2, IFN-γ) and anti-inflammatory (IL-4 and IL-10) cytokines were up-regulated in tracheo-bronchial lymph nodes of HV, but not in LV, compared to the control group (P < 0.05). IL-12 mRNA level was up-regulated in tracheo-bronchial lymph nodes of both LV and HV groups (P ≤ 0.05). A significant up-regulation of IL-15 mRNA was observed in tracheo-bronchial lymph nodes for LV calves (P < 0.002), but not for HV calves. Experimental inoculation with BVDV-2 1373 stimulated significant mRNA expression of pro-inflammatory and anti-inflammatory cytokines. In contrast, inoculation with BVDV-1a SD-1 only resulted in up-regulation of IL-12 and IL-15 mRNA, which is associated with activation of macrophages and NK cells during innate immune response.  相似文献   

2.
Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period.A total of 455 live born Holstein calves (N: No assistance, n = 360; FN: Farmer assistance but normally presented calf, n = 82; FM: Farmer assistance of malpresented calf, n = 13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P < 0.001) and FN calves had lower passive immune transfer (P = 0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P > 0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P < 0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8×; P < 0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P > 0.05).Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia.  相似文献   

3.
Our objective was to determine cow- and herd-level risk factors associated with seropositivity for Neospora caninum in a large number of randomly selected Canadian dairy herds, controlling for important confounding variables and co-infections with bovine leukemia virus (BLV), bovine viral diarrhea virus (BVDV) and Mycobacterium avium subspecies paratuberculosis (MAP). Serum samples were obtained from 30 randomly selected cows, where available, in 240 herds using monthly milk testing, within 6 of 10 provinces, and these samples were tested for antibodies against BLV, MAP and N. caninum using commercially available ELISA test kits. Five unvaccinated cattle >6 months old from each herd were tested for antibodies to BVDV using virus neutralization. Most herd-level predictors were obtained through personal interviews with questionnaires administrated to each farm manager. A mixed logistic-regression model was built using N. caninum serostatus at the cow-level as the outcome variable, with herd as a random effect and province as a fixed effect. A BLV seropositive cow was 1.50 times more likely to be seropositive for N. caninum than a BLV-seronegative cow, and this was the only cow-level variable to remain in the final model. Regarding herd-level variables, with “no on-farm dogs” as the baseline, “presence of dogs but not known to eat placentas and/or fetuses” increased the odds of seropositivity for N. caninum by a factor of 1.66. For “presence of dogs known to eat placentas and/or fetuses”, the odds ratio (OR) was 2.75, demonstrating a dose–response relationship. “Using embryo transfer” (OR = 0.69), “asking for a BVDV-negative test before introducing an animal” (OR = 0.30), “using monensin in dry cows” (OR = 0.71), and “heifers having nose-to-nose contact with calves” (OR = 0.73) were all dichotomous variables negatively associated with seropositivity for N. caninum. “Number of milk cows on the farm” (OR = 0.99), and “area (acres) used for forage production” (OR = 0.99) were continuous variables negatively associated with N. caninum seropositivity.  相似文献   

4.
The aim of the present study was to determine the serological response of heifers after vaccination with two inactivated bovine viral diarrhoea virus (BVDV) vaccines by means of various ELISA tests. Three dairy farms were selected from the Galicia region of Spain. In each herd, a batch of heifers to be vaccinated for the first time was selected and followed for 15 months. Heifers from farm 1 (n = 25) were vaccinated with Vaccine A, whereas heifers from farm 2 (n = 16) were vaccinated with Vaccine B. Heifers from farm 3 (n = 17), where no BVDV vaccines were used, acted as controls. Blood samples were analyzed periodically for BVDV antibodies, using five commercial ELISAs, based on BVDV p80 antigen or whole virus.At the end of the study, none of the animals vaccinated with Vaccine A seroconverted according to p80 antibody status, whereas up to 80% tested positive by ELISA against whole virus antigen. For the animals vaccinated with Vaccine B, 2/16 animals seroconverted according to p80 antibody ELISAs, whereas all had seroconverted according to the ELISA against whole virus antigen. In most cases, based on the use of ELISAs to detect specific antibodies against the p80 protein, at 15 months post-vaccination with inactivated BVDV vaccines the responses did not seem to interfere with detection of antibody to BVDV infection. However, the finding of a small proportion of vaccinated animals seropositive against BVDV p80 antigen suggests that antibodies that interfere with diagnosis of BVDV infection within the herd could exist, even when using p80 ELISAs.  相似文献   

5.
The objective of this pilot study was to compare the cytokine profile as well as cell-mediated and antibody responses of foals infected with a low inoculum of virulent Rhodococcus equi resulting in subclinical pneumonia to that of foals infected with a high inoculum resulting in severe clinical pneumonia. The mean (±SD) ratio of post-infection to pre-infection anti-R. equi IgG(T) concentration was significantly (P = 0.002) higher in foals infected with the high inoculum (195 ± 145; range 62–328) compared to foals infected with the low inoculum (3.9 ± 4.5; range 0.5–11). Similarly, mean (±SD) ratio of post-infection to pre-infection IgM concentration was significantly (P = 0.002) higher in foals infected with the high inoculum (12 ± 4.0; range 7.4–14) compared to foals infected with the low inoculum (2.5 ± 1.5; range 1.2–4.7). Proliferative responses to R. equi antigens as well as expression of mRNA for IL-2, IL-4, IL-10, and IFN-γ in BLN were not significantly different between the two groups. There was a tendency (P = 0.073) towards a higher IFN-γ/IL-4 ratio in the low inoculum group. This study demonstrates that the size of inoculum modulates the IgG subisotype response and possibly the cytokine profile of foals.  相似文献   

6.
The objective of this study was to compare the mRNA expression of Toll-like receptors (TLR3 and TLR7), and costimulatory molecules involved in activation of lymphocytes and antigen presenting cells (CD80, CD86, CD28, and CD40L) after experimental infection of beef calves with low or high virulence noncytopathic (ncp) bovine viral diarrhea virus (BVDV) strains. Thirty BVDV-naïve, beef calves were intranasally inoculated with low (LV; n?=?10, SD-1) or high (HV; n?=?10, 1373) virulence ncp BVDV or with BVDV-free cell culture medium (Control, n?=?10). Calves were euthanized on day 5 post-inoculation and tracheo-bronchial lymph node (TBLN) and spleen samples were collected for mRNA expression through quantitative-RT-PCR. Levels of mRNA for TLR3 and TLR7 were increased in spleen of HV group (P?mRNA was up-regulated in TBLN of both LV and HV groups (P?mRNA was observed in TBLN for LV calves (P?相似文献   

7.
One hundred and twenty-four calves with neonatal diarrhoea were investigated in order to assess the prevalence of hyperkalaemia and the associated clinical signs. Hyperkalaemia (potassium concentration >5.8 mmol/L) was recognized in 42 (34%) calves and was more closely associated with dehydration than with decreases in base excess or venous blood pH. In 75 calves with normal blood concentrations of D-lactate (i.e. ?3.96 mmol/L), K concentrations were moderately correlated with base excess values (r = ?0.48, P < 0.001). In contrast, no significant correlation was observed in 49 calves with elevated D-lactate. Only three hyperkalaemic calves had bradycardia and a weak positive correlation was found between heart rate and K concentrations (r = 0.22, P = 0.014). Ten of the 124 calves had cardiac arrhythmia and of these seven had hyperkalaemia indicating that cardiac arrhythmia had a low sensitivity (17%) but a high specificity (96%) as a predictor of hyperkalaemia.In a subset of 34 calves with base excess values ??5 mmol/L and D-lactate concentrations <5 mmol/L (of which 22 had hyperkalaemia), changes in posture/ability to stand could be mainly explained by elevations of K concentrations (P < 0.001) and to a lesser extent by increases in L-lactate concentrations (P = 0.024). Skeletal muscle weakness due to hyperkalaemia alongside hypovolaemia may produce a clinical picture that is similar to that in calves with marked D-lactic acidosis. However, since reductions in the strength of the palpebral reflex are closely correlated with D-lactate concentrations, a prompt palpebral reflex can assist the clinical prediction of hyperkalaemia in calves presenting with a distinct impairment in their ability to stand (specificity 99%, sensitivity 29%).  相似文献   

8.
Two experiments were conducted to determine the effects of pre-weaning vitamin E, Se, and Cu supplementation on performance and immune response in stressed calves. In Exp. 1, 71 Hereford x Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (E), 3) control plus 10 mg Cu/kg DM (CU), or 4) a combination of E and CU treatments (ECU). In Exp. 2, 80 Hereford (Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 0.3 mg Se/kg DM (SE), 3) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (LOWE), 4) control plus 1000 IU vitamin E + 0.3 mg Se/kg DM (MEDE), or 5) control plus 1500 IU vitamin E + 0.3 mg Se/kg DM (HIE). Treatments continued for 49 (Exp. 1) or 53 d (Exp. 2) prior to weaning. At weaning all calves were transported to feedlot facilities. In Exp. 1, vitamin E tended (P<0.09) to improve post-weaning ADG and reduce (P<0.06) plasma haptoglobin (Hp), but had no effect on plasma α-tocopherol. Dietary Cu tended to increase (P<0.01) liver Cu stores, and antibody titers to bovine viral diarrhea (BVD) were greater (P<0.04) at weaning in CU and E calves. In Exp. 2, vitamin E tended to increase serum α-tocopherol (P<0.06) and cortisol (P<0.08). Vitamin E and Se supplementation may improve post-weaning performance and decrease plasma Hp concentrations in stressed calves.  相似文献   

9.
This study assessed the effects of age at weaning (early weaning at 90 d or traditional weaning at 150 d) and breed (Parda de Montaña or Pirenaica) on calf performance and carcass and meat quality in autumn-calving beef cattle. At calving, 14 Parda de Montaña and 14 Pirenaica cow–calf pairs were randomly assigned to one of two weaning treatments, and kept indoors during lactation. After weaning, calves were fed an intensive diet until slaughter at 450 kg. The interaction between age at weaning and breed was not significant for any of the parameters studied. From 90 d to 150 d, early weaned calves had greater ADG (P = 0.001) and IGF-I concentrations (P = 0.001) than traditionally weaned calves, but their leptin concentrations were similar (P = 0.15). During the finishing phase, performance, daily feed intake, and efficiency did not differ between treatments. Early weaning did not affect age at slaughter, carcass weight, fatness score, fat colour, and meat quality, but improved carcass conformation (P = 0.04). Early weaned calves had greater total DMI (P = 0.002) with greater concomitant feed costs (P = 0.001) and yielded a slightly greater income than traditionally weaned calves; therefore, economic margins did not differ. Parda de Montaña calves tended to have greater ADG from birth to 90 d and were heavier at 90 d (P = 0.01) than were Pirenaica calves. From 90 d to 150 d, performance and IGF-I and leptin concentrations did not differ between breeds; thus, Parda de Montaña calves remained heavier at 150 d. During the finishing phase, at times, weight gains of Parda de Montaña and Pirenaica calves differed, but the overall performance, feed intake, and efficiency of the two breeds were similar. Pirenaica calves had heavier carcasses (P = 0.04) with greater conformation scores (P = 0.04) than Parda de Montaña calves; thus, income per carcass was greater for the former than the latter (P = 0.007). As feed costs were similar for both breeds, the economic margin of Pirenaica calves was greater than that of Parda de Montaña calves (P = 0.01). In conclusion, in both breeds weaning strategies had similar effects on performance and carcass and meat quality; however, from an economic point of view, and considering only the costs associated with the calf, raising Pirenaica calves would be more profitable, at either age at weaning.  相似文献   

10.
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11.
The objectives of the current research were to determine the physiological effects and responses of many leukocytes following surgical castration and/(or) physical dehorning and the influence of anesthetics and analgesics in 3-month-old calves. Eighty 3-month-old Holstein bull calves were completely randomized to treatments in a 2 × 2 × 2 factorial arrangement with castration, dehorning, and anesthetic/analgesic as the main effects. Peripheral blood samples were collected just before (0) and 0.5, 1.5, 2.5, 4, 6, 24, and 72 h after the respective procedure(s) and analyzed for total leukocyte and differential counts, as well as plasma cortisol and haptoglobin concentrations. Blood from the 0, 0.5 and 24 h collections were analyzed for many ex vivo leukocyte responses. Data were analyzed using a repeated measures analysis of variance with the fixed effects of treatment, time, and the interaction of treatment × time. Pre-planned contrasts were performed to determine the effect of (1) management procedure (castration and/(or) dehorning), (2) anesthetic/analgesic, and (3) were the management procedures additive. There were treatment × time interactions (P < 0.05) on plasma cortisol and haptoglobin concentrations as well as for total leukocyte and neutrophil concentrations in blood. Castration and dehorning increased cortisol concentrations and the effect of the procedures was additive (P < 0.02). Dehorning alone elicited a greater (P < 0.05) cortisol response than castration alone. In contrast, the leukocytosis and neutrophilia was greater (P < 0.01) among castrated calves. In addition, haptoglobin concentrations at 24 h after castration were elevated (P < 0.01) in calves that were castrated. Both castration and dehorning suppressed (P = 0.04) many leukocyte responses including the secretion of tumor necrosis factor-α when whole blood cultures were stimulated with lipopolysaccharide, surface expression of l-selectin on peripheral blood neutrophils, and the oxidative burst intensity of peripheral blood neutrophils when co-cultured with an Escherichia coli. The effects of castration and dehorning on blood leukocyte counts or any of the leukocyte responses were not additive (P > 0.23). Castration and dehorning effects of plasma haptoglobin concentrations tended (P = 0.10) to be additive at 72 h after the procedure(s). Prior administration of local anesthetic and a systemic analgesic attenuated (P < 0.001) the cortisol response and prevented (P = 0.03) the observed leukocytosis, neutrophilia, and leukocyte suppression. These data suggest that calves should be castrated and dehorned on the same day rather than spreading them out across two days and calves should be administered pain relief prior to performing either procedure.  相似文献   

12.
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13.
This longitudinal observational study was conducted to investigate the spontaneous effect of Giardia and Cryptosporidium infections on acute phase response (APR) in reindeer calves (Rangifer tarandus tarandus) in Finnish Lapland.Serum (n = 609) and faecal samples (n = 366) were collected from 54 reindeer calves aged zero to 33 days. The samples were analysed for Giardia, Cryptosporidium, acute phase proteins (APP) and γ-globulins.Linear regression models were used to investigate associations of early Giardia infection (before 12 days of life) with the response of APPs and acquiring of passive immunity.Giardia was detected in 100% and Cryptosporidium in 23% of calves. There was a negative association between early Giardia infection and γ-globulin concentrations (p = 0.032) and a positive association with serum amyloid A (SAA) concentrations (p = 0.042). The results suggest a protective effect of colostrum against Giardia infection and that early infection may induce activation of APR.  相似文献   

14.
Bovine viral diarrhea virus (BVDV) is considered an important cause of economic loss within bovine herds worldwide. In Argentina, only the use of inactivated vaccines is allowed, however, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. The use of recombinant subunit vaccines has been proposed as an alternative to overcome this difficulty. Different studies on protection against BVDV infection have focused the E2 protein, supporting its putative use in subunit vaccines. Utilization of transgenic plants expressing recombinant antigens for the formulation of experimental vaccines represents an innovative and cost effective alternative to the classical fermentation systems.The aim of this work was to develop transgenic alfalfa plants (Medicago sativa, L.) expressing a truncated version of the structural protein E2 from BVDV fused to a molecule named APCH, that target to antigen presenting cells (APCH-tE2). The concentration of recombinant APCH-tE2 in alfalfa leaves was 1 μg/g at fresh weight and its expression remained stable after vegetative propagation. A methodology based an aqueous two phases system was standardized for concentration and partial purification of APCH-tE2 from alfalfa. Guinea pigs parentally immunized with leaf extracts developed high titers of neutralizing antibodies. In bovine, the APCH-tE2 subunit vaccine was able to induce BVDV-specific neutralizing antibodies. After challenge, bovines inoculated with 3 μg of APCH-tE2 produced in alfalfa transgenic plants showed complete virological protection.  相似文献   

15.
The objective was to detect presence of calves excreting Mycobacterium avium subsp. paratuberculosis (MAP) in their feces as a consequence of being born to MAP fecal culture positive (vs. negative) dams. For each cow that was about to calf, approximately 10 g of feces was collected manually by the herdsmen from the rectum using a disposable plastic examination sleeve within 48–72 h prior to actual calving. Between 1 and 3 d of birth, herd personnel collected approximately 10 g of fecal samples followed by monthly visits to the farm at which time 10 g of fecal samples were again collected by study investigators from each calf at approximately 30, 60 and 90 d of age. Mycobacterium avium subsp. paratuberculosis was recovered from 8% (5/60) of the cows that gave birth to calves. However, MAP was not recovered from any of the fecal samples (0/240) collected from study calves. Findings of the present study suggest lack of evidence for fecal excretion of MAP in calves born to fecal culture positive (vs. negative) dams in a heavily infected herd.  相似文献   

16.
《Livestock Science》2006,99(1):21-27
The present study evaluated the effect of restricted suckling (RS) on some physiological and behavioural stress measures compared to artificial rearing (AR). Thirty Holstein × Zebu cows and their calves were randomly assigned to one of two treatments. Cows were milked once daily. All calves were tethered in front of their dams during milking permitting physical contact between them in order to stimulate milk ejection, starting at 5 days of age. Calves in the RS treatment were allowed to suckle during 60 min daily, 30 min after milking and 30 min in the afternoon, while calves in the AR treatment were fed milk from teat bottles at the same times. Data were collected from day 4 to day 9, while treatments started on day 5. Heart and respiratory rates, body weight and temperature were measured (in that order) 15 min before entry into the milking parlour. Blood samples and pedometer readings were collected about 50 min later, immediately on return to their home pens. Higher heart rate in calves was found in the RS group than in the AR group. However, cortisol concentration was higher (P < 0.05) in the AR than in the RS group. No difference was found in average weight gain, milk consumption, number of steps counted, body temperature and respiratory rate in RS and AR calves. AR induced significantly (P < 0.05) higher level of serum cortisol concentration in the cows than did RS. No difference (P > 0.05) was found in body temperature, heart and respiratory rates in RS and AR treatments. It was concluded that suckling and nursing reduces some stress parameters in calves and cows in the AR treatment.  相似文献   

17.
This study describes and compares the pharmacokinetics of a single 7.5 mg/kg dose of cephalexin monohydrate oil-based 20% suspension after its administrations to six cows by the intramuscular (i.m.) and subcutaneous (s.c.) routes, and to five calves by the i.m. route. Significantly (P < 0.05) higher peak plasma concentrations (5.6 ± 0.79 μg/ml versus 3.93 ± 1.24 μg/ml) and lower half-life (1.81 ± 0.56 h versus 4.21 ± 0.82 h) and mean residence time (4.12 ± 1.07 h versus 6.63 ± 0.85 h) were obtained after i.m. administration when compared to the s.c. administration to cows. No differences were found between pharmacokinetic parameters calculated for cows and calves. Cephalexin plasma concentrations remained above 0.5–0.75 μg/ml for 11–14 h and 8–9 h after the s.c. and i.m. administrations, respectively. Thus, route of administration may be an important issue to be considered when calculating dosage schedules for successful treatments and safe withdrawal times for veterinary medicines.  相似文献   

18.
The aim of the study was to describe, over a period of 24 weeks, the pathological and bacteriological changes in badgers experimentally infected with Mycobacterium bovis. The badgers were infected by endobronchial instillation of 2.5 × 104 colony forming units (cfu) M. bovis. After infection, the badgers were examined at 3 weekly intervals when blood and tracheal aspirates were collected. At 6, 12, 18 and 24 weeks post-infection (pi) three animals were euthanized and a detailed pathological and bacteriological examination was performed to assess the nature of the experimental disease. During the course of the study only one badger developed clinical signs of disease: a subcutaneous swelling on its head, first observed at 18 weeks pi. At post-mortem examination gross and histological lesions of tuberculosis were observed and M. bovis was recovered from all, except one badger. In the majority of badgers the endobronchial route of inoculation resulted in the establishment of infection that over 24 weeks was non-progressive with limited dissemination of infection from the thoracic cavity, mainly to the hepatic and mesenteric lymph nodes. However, in one of the badgers examined at 18 weeks pi and one at 24 weeks pi, infection was widely disseminated. The disease induced by the endobronchial inoculation displayed the characteristics of disease observed in naturally infected badgers.  相似文献   

19.
Feline chronic gingivostomatitis (FCGS) is an inflammatory disease of the oral cavity that causes severe pain and distress in affected cats. Treatment methods are currently very limited. The aims of this study were to assess the feline innate immune response by investigating the levels of cytokine and Toll-like receptor (TLR) mRNAs in tissue biopsies of cats with and without FCGS, and to relate this to the presence or absence of putative oral pathogens identified previously within these cats. Mucosal biopsies were collected from 28 cats with FCGS and eight healthy cats. The levels of TLR (TLR2, TLR3, TLR4, TLR7, TLR9) and cytokine (IL-1β, IL-4, IL-6, IL-10, IL-12, TNF-α, IFN-γ) mRNA was determined using quantitative PCR. In the FCGS group a statistically significant increase was seen in TLR2, TLR7, TNF-α, IFN-γ, IL-1β and IL-6 mRNA levels compared to the healthy group. In cats where Tannerella forsythia was present, statistically significant increases were seen in TLR2, TLR4, TLR7, TLR9, TNF-α and IL-1β mRNA levels compared to cats where this putative pathogen was absent. Statistically significant increases in mRNA expression were also seen in cats harbouring feline calicivirus (FCV) (TLR2, IL-1β, IL-6, IFN-γ) and Porphyromonas circumdentaria (TLR2, TLR3) compared to cats where these putative pathogens were absent. Pasteurella multocida subsp. multocida and Pseudomonas sp. did not significantly alter the expression of any TLR or cytokine mRNAs when compared to animals who tested negative for these species, while cats colonised with P. multocida subsp. septica demonstrated a statistically significant reduction in the expression of TLR7, TNF-α and IFN-γ mRNAs compared to cats free of this species. The expression of mRNA for several TLRs and cytokines is elevated in FCGS. A positive correlation was observed between clinical disease severity and the presence of FCV (p = 0.001; Rho = 0.58). Although the number of cats harbouring T. forsythia was low by comparison, 80% of samples in which it was present were from cases with the highest clinical disease severity. Positive correlations with clinical disease severity were seen for TLR2 (p = 0.00086), TLR7 (p = 0.049), TNF-α (p = 0.027), IFN-γ (p = 0.0015), IL-1β (p = 0.004) and IL-6 (p = 0.00001) mRNAs. The putative pathogens FCV and T. forsythia may be important in stimulating a host immune response to FCGS and may play a role in the pathogenesis of this disease.  相似文献   

20.
Our objective was to develop a lipopolysaccharide (LPS) inflammation model in calves to evaluate the acute-phase response with respect to the release of pro-inflammatory cytokines and acute-phase proteins, fever development and sickness behaviour. Fourteen 4-week-old male Holstein Friesian calves were included and randomly assigned to a negative control group (n = 3) and an LPS-challenged group (n = 11). The latter received an intravenous bolus injection of 0.5 μg of LPS/kg body weight. Blood collection and clinical scoring were performed at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 18, 24, 28, 32, 48, 54 and 72 h post LPS administration (p.a.). In the LPS group, the following clinical signs were observed successively: tachypnoea (on average 18 min p.a.), decubitus (29 min p.a.), general depression (1.75 h p.a.), fever (5 h p.a.) and tachycardia (5 h p.a.). Subsequent to the recovery from respiratory distress, general depression was prominent, which deteriorated when fever increased. One animal did not survive LPS administration, whereas the other animals recovered on average within 6.1 h p.a. Moreover, the challenge significantly increased plasma concentrations of tumour necrosis factor-α, interleukin 6, serum amyloid A and haptoglobin, with peaking levels at 1, 3.5, 24 and 18 h p.a., respectively. The present LPS model was practical and reproducible, caused obvious clinical signs related to endotoxemia and a marked change in the studied inflammatory mediators, making it a suitable model to study the immunomodulatory properties of drugs in future research.  相似文献   

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