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1.

Background

Mannheimia haemolytica is an important etiological agent in bovine respiratory disease.

Objectives

Explore risk factors for recovery of susceptible and resistant M. haemolytica in feedlot cattle and explore associations with health outcomes.

Animals

Cattle (n = 5,498) from 4 feedlots sampled at arrival and later in feeding period.

Methods

Susceptibility of M. haemolytica isolates tested for 21 antimicrobials. Records of antimicrobial use and health events analyzed using multivariable regression.

Results

M. haemolytica recovered from 29% of cattle (1,596/5,498), 13.1% at arrival (95% CI, 12.3–14.1%), and 19.8% at second sampling (95% CI, 18.7–20.9%). Nearly half of study cattle received antimicrobial drugs (AMDs) parenterally, mostly as metaphylactic treatment at arrival. Individual parenteral AMD exposures were associated with decreased recovery of M. haemolytica (OR, 0.2; 95% CI, 0.02–1.2), whereas exposure in penmates was associated with increased recovery (OR, 1.5; 95% CI, 1.05–2.2). Most isolates were pan‐susceptible (87.8%; 95% CI, 87.0–89.4%). AMD exposures were not associated with resistance to any single drug. Multiply‐resistant isolates were rare (5.9%; 95% CI, 5.1–6.9%), but AMD exposures in pen mates were associated with increased odds of recovering multiply‐resistant M. haemolytica (OR, 23.9; 95% CI, 8.4–68.3). Cattle positive for M. haemolytica on arrival were more likely to become ill within 10 days (OR, 1.7; 95% CI, 1.1–2.4).

Conclusions and Clinical Importance

Resistance generally was rare in M. haemolytica. Antimicrobial drug exposures in penmates increased the risk of isolating susceptible and multiply‐resistant M. haemolytica, a finding that could be explained by contagious spread.  相似文献   

2.
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3.
《Veterinary microbiology》2015,175(1):114-122
Mannheimia haemolytica is the primary bacterial agent in the bovine respiratory disease complex. It is thought that M. haemolytica colonizes the tonsillar crypts of cattle as a commensal and subsequently descends into the lungs to cause disease. Many bacterial species persist in the host as biofilms. There is limited information about the ability of M. haemolytica to form biofilms. The aim of this study was to develop an in vitro model for M. haemolytica biofilm formation. We found that M. haemolytica required at least 36 h to form robust biofilms on plastic in vitro when incubated in RPMI-1640 tissue culture medium at 37 °C, with maximal biofilm formation being evident at 48 h. Biofilm formation was inhibited by adding the monosaccharides d(+) galactose and d(+) mannose to the growth medium. Addition of antibodies to the M. haemolytica surface protein OmpA also reduced biofilm formation. Upon evaluating the macromolecules within the biofilm extracellular polymeric substance we found it contained 9.7 μg/cm2 of protein, 0.81 μg/cm2 of total carbohydrate, and 0.47 μg/cm2 of extracellular DNA. Furthermore, proteinase K treatment significantly decreased biofilms (P < 0.05) while α-amylase and micrococcal nuclease decreased biofilms to a lesser extent. M. haemolytica biofilm cells were more resistant than planktonic cells to the antibiotics florfenicol, gentamicin, and tulathromycin. These results provide evidence that M. haemolytica can form biofilms, which could contribute to its ability to persist as a commensal in the bovine upper respiratory tract.  相似文献   

4.
The primary objective of this study was to determine, at the lung level, whether single or multiple clones of Mannheimia haemolytica are present within a pen during a bovine respiratory disease (BRD) episode. A secondary objective was to assess whether M. haemolytica isolates obtained from nasal swabs (NS) are identical to those isolated deeper within the respiratory tract. Sixteen BRD episodes that naturally occurred in 12 pens of eight to 12 bulls (n = 112) newly-received at three fattening operations were investigated. One hundred and seventy five M. haemolytica isolates were collected from 239 pairs of trans-tracheal aspirations (TTA) and NS performed during these 16 BRD episodes. M. haemolytica isolates were characterized by pulsed-field gel electrophoresis (PFGE). PFGE types obtained from NS and TTA were then compared. M. haemolytica was isolated during 14 BRD episodes. Two to three different clones of M. haemolytica were recovered during 10 episodes whereas only one clone was recovered in four episodes. A moderate agreement (kappa = 0.50) between NS and TTA for M. haemolytica isolation was observed. Identical PFGE types were only observed in 77% of matched NS-TTA pairs. The significant within-pen diversity of M. haemolytica during BRD episodes indicates that the disease is not primarily due to the spread of a single virulent clone among cattle and highlights the importance of predisposing factors that enable the resident flora to overcome the cattle's immune system. The results also demonstrate that isolates recovered from NS are not always representative of the isolates present deeper within the respiratory tract.  相似文献   

5.
Objective of the work was to study whether Mannheimia haemolytica may be transmitted from the mouth of the lambs into the teat of the dam during sucking. We compared bacterial populations within the teat duct and milk of ewes immediately before and immediately after sucking by the lambs. Tonsils of lambs of the ewes were swabbed. M. haemolytica strain DAG21T recovered from a teat duct of a ewe was compared to strain DAG21R recovered from the tonsils of her lamb by using 16s rRNA sequencing. We used those two isolates and another one of known pathogenicity, for challenging ewes: (i) 2-mm deep into healthy teats, (ii) 2-mm deep into teats with chapping lesions or (iii) into the cistern of healthy mammary glands. Of samples collected before suckling, 20/792 were bacteriologically positive, and of those after, 50/792 were bacteriologically positive (P < 0.001); in 37 cases, a negative sample became positive. One M. haemolytica (DAG21T) was recovered after suckling from a teat duct of a ewe. The organism was isolated from 57/90 tonsillar swabs from lambs. Risk of infection of ewe’ teats was 0.004 throughout lactation, being greatest (0.021) during the 3rd week of lactation. The 16s rRNA sequences of strains DAG21T and DAG21R were identical over 1450 nucleotides. Phylogenetic analysis showed that the two isolates clustered together with isolates of M. haemolytica. Organism deposition into healthy teats caused subclinical mastitis; deposition into teats with lesions or directly into mammary gland caused clinical mastitis. When results of inoculation of the three strains were compared between them, statistical significance was always P > 0.9. Results provide clear evidence that suckling by lambs can lead to transmission of M. haemolytica into the teats of the ewes; the bacteria have the potential to cause mastitis if circumstances are favourable.  相似文献   

6.
Mannheimia haemolytica and Histophilus somni are frequently isolated from diseased cattle with bovine respiratory disease (BRD). They compromise animal lung function and the immune responses generated are not sufficient to limit infection. Identification of specific immunogenic antigens for vaccine development represents a great challenge. Immunogenic proteins were identified by immunoproteomic approach with sera from cattle immunized with a commercial cellular vaccine of M. haemolytica and H. somni. Proteins of M. haemolytica were identified as solute ABC transporter, iron-binding protein, and hypothetical protein of capsular biosynthesis. Histophilus somni proteins correspond to porin, amino acid ABC transporter, hypothetical outer membrane protein, cysteine synthase, and outer membrane protein P6. Although these antigens share strong similarities with other proteins from animal pathogens, the ABC system proteins have been associated with virulence and these proteins could be considered as potential vaccine candidates for BRD.  相似文献   

7.
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8.
Pleuritic chest pain from bacterial pneumonia is often reported in human medicine. However, studies investigating pain associated with bovine respiratory disease (BRD) are lacking. The objectives of this study were to assess if bacterial pneumonia elicits a pain response in calves with experimentally induced BRD and to determine the analgesic effects of transdermally administered flunixin. A total of 26 calves, 6–7 mo of age, with no history of BRD were enrolled into one of three treatment groups: 1) experimentally induced BRD + transdermal flunixin at 3.3 mg/kg twice, 24 h apart (BRD + FTD); 2) experimentally induced BRD + placebo (BRD + PLBO); and 3) sham induction + placebo (CNTL + PLBO). Calves induced with BRD were inoculated with Mannheimia haemolytica via bronchoalveolar lavage. Outcomes were collected from −48 to 192 h post-treatment and included serum cortisol, infrared thermography, mechanical nociceptive threshold, substance P, kinematic gait analysis, visual analog scale (VAS), clinical illness score, computerized lung score, average activity and rumination level, prostaglandin E2 metabolite, plasma serum amyloid A, and rectal temperature. Outcomes were evaluated using either a generalized logistic mixed model for categorical variables or a generalized linear mixed model for continuous variables. Right front force differed by treatment (P = 0.01). The BRD + PLBO had lower mean force applied to the right front limb (85.5 kg) compared with BRD + FTD (96.5 kg; P < 0.01). Average VAS differed by a treatment by time interaction (P = 0.01). The VAS scores differed for BRD + PLBO at −48 (3.49 mm) compared with 168 and 192 h (13.49 and 13.64 mm, respectively) (P < 0.01). Activity for BRD + PLBO was higher at −48 h (27 min/h) compared with 48, 72, 120, and 168 h (≤ 22.24 min/h; P < 0.01). Activity differed by a treatment by time interaction (P = 0.01). Activity for BRD + FTD was higher at −48 and 0 h (28.2 and 28.2 min/h, respectively) compared to 48, 72, 96, and 168 h (≤23.7 min/h; P < 0.01). Results show a combination of reduced activity levels, decreased force on the right front limb, and increased VAS pain scores all support that bacterial pneumonia in cattle is painful. Differences in right front force indicate that flunixin transdermal may attenuate certain pain biomarkers in cattle with BRD. These findings suggest that BRD is painful and analgesic drugs may improve the humane aspects of care for cattle with BRD.  相似文献   

9.
The efficacy of a Pasteurella haemolytica vaccine (PhV) administered once to calves within 24 hours of arrival at a feedlot was tested for the ability to prevent morbidity and mortality from all bovine respiratory disease (BRD) and specifically from fibrinous pneumonia mortality. The PhV consisted of two immunizing ingredients: outer membrane proteins extracted from P. haemolytica, plus genetically attenuated leukotoxin produced by recombinant DNA technology. This double blind study was conducted at a large Saskatchewan feedlot using 2,324 high-risk calves purchased at auction markets and kept under typical commercial feedlot conditions. The trial design included four vaccine test groups: 1) PhV and a bovine herpesvirus type-1 (BHV-1) subunit vaccine comprised only of the virus glycoprotein IV (gIV); 2) PhV and a commercial modified live vaccine (MLV) containing BHV-1 and parainfluenza-3 viruses; 3) gIV alone; and 4) MLV alone. Calves were assigned to vaccine groups in a random systematic manner, individually identified, and monitored for 90 days after vaccination. The vaccines were given once, on arrival, to reflect common feedlot practice, although vaccination prior to expected risk would be more appropriate.

The PhV in combination with gIV reduced BRD morbidity by 20% (p < 0.05) compared to gIV alone and 24% (p < 0.05) compared to MLV alone, and reduced BRD mortality by 88% (p < 0.05) and fibrinous pneumonia mortality by 100% (p < 0.05) when compared to either gIV or MLV alone. Vaccination with PhV in combination with MLV significantly reduced the efficacy of the PhV in preventing BRD morbidity, BRD mortality, and fibrinous pneumonia mortality and also reduced the antibody response to P. haemolytica leukotoxin. These results suggest that the MLV interfered with the protective capacity of the PhV.

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10.
Polymorphonuclear cells diapedesis has an important contribution to the induced Mannhemia haemolytica (M. haemolytica) infection lung inflammation and IL-8 is the primary polymorphonuclear chemoattractant. Using a bovine IL-8/luciferase transiently transgenized mouse model, the orchestration among M. haemolytica, IL-8 promoter activation and neutrophilia was followed in real time by in vivo image analysis.  相似文献   

11.
Mannheimia haemolytica is the principal bacterial pathogen associated with bovine respiratory disease (BRD). As an opportunistic pathogen, M. haemolytica is also frequently isolated from the respiratory tract of healthy cattle. This study examined the characteristics of M. haemolytica collected using deep nasal swabs from healthy cattle (n = 49) and cattle diagnosed with BRD (n = 41). Isolates were analyzed by pulsed-field gel electrophoresis (PFGE), serotyped, and tested for antimicrobial susceptibility. Polymerase chain reaction (PCR) was used to screen isolates for virulence [leukotoxin C (lktC), putative adhesin (ahs), outer-membrane lipoprotein (gs60), O-sialoglycoprotease (gcp), transferring-binding protein B (tbpB) and UDP-N-acetyl-D-glucosamine-2-epimerase (nmaA)] and antimicrobial resistance [tet(H), blaROB-1, erm(X), erm(42), msr(E)-mph(E) and aphA-1] genes. Isolates were genetically diverse but in three instances, M. haemolytica with the same pulsotype, resistance phenotype, and genotype were collected from cattle with BRD. This occurred once between cattle located in two different feedlots, once between cattle in the same feedlot, but in different pens, and once among cattle from the same feedlot in the same pen. Isolates from healthy cattle were primarily serotype 2 (75.5%) while those from individuals with BRD were serotype 1 (70.7%) or 6 (19.5%). Resistance to at least one antibiotic occurred more frequently (P < 0.001) in M. haemolytica collected from cattle with BRD (37%) compared with those that were healthy (2%). Overall, tetracycline resistance (18%) was the most prevalent resistant phenotype. All tetracycline-resistant M. haemolytica encoded tet(H). Ampicillin resistance (6%) and neomycin resistance (15%) were detected and corresponded to the presence of the blaROB-1 and aphA-1 genes, respectively. Tilmicosin resistance (6%) was also detected, but the resistance genes responsible were not identified. The virulence genes lktC, ahs, gs60, and gcp were present in all isolates examined, while tbpB and nmaA were only detected in serotype 1 and serotype 6 isolates indicating they may be potential targets for serotype-specific identification or vaccine development. These results provide the first reported evidence of transmission and spread of antimicrobial-resistant M. haemolytica that have contributed to bovine respiratory disease in western Canadian feedlots.  相似文献   

12.
The effects of papaverine on carbachol (CCh) -and high K+- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 µM) -and KCl (65 mM) -induced contractions in a concentration-dependent manner. Forskolin or sodium nitroprusside inhibited CCh-induced contractions in a concentration-dependent manner in association with increases in the cAMP or cGMP contents, whereas papaverine increased cGMP contents only at 30 µM. Changes in the extracellular Ca2+ from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high K+-depolarized muscles, but papaverine-induced relaxation did not change. Futhermore, papaverine (30 µM) and NaCN (300 µM) decreased the creatine phosphate contents. These results suggest that the relaxing effects of papaverine on the bovine abomasum are mainly due to the inhibition of aerobic energy metabolism.  相似文献   

13.
Respiratory infection of cattle with bovine herpesvirus type 1 (BHV-1) predisposes cattle to secondary pneumonia with Mannheimia haemolytica as part of the bovine respiratory disease complex (BRD). One cell type that has received limited investigation for its role in the inflammation that accompanies BRD is the respiratory epithelial cell. In the present study we investigated mechanisms by which BHV-1 infection of respiratory epithelial cells contributes to the recruitment and activation of bovine polymorphonuclear neutrophils (PMNs) in vitro. Primary cultures of bovine bronchial epithelial (BBE) cells were infected with BHV-1 and assessed for cytokine expression by real-time PCR. We found that BHV-1 infection elicits a rapid IL-1, IL-8 and TNF-α mRNA response by BBE cells. Bovine PMNs exhibited greater adherence to BHV-1 infected BBE cells than uninfected cells. The increased adherence was significantly reduced by the addition of an anti-IL-1β antibody or human soluble TNF-α receptor (sTNF-αR). Pre-incubation of bovine PMNs with conditioned media from BHV-1 infected BBE cells increased PMN migration, which was inhibited by addition of an anti-IL-1β antibody, sTNF-αR, or an IL-8 peptide inhibitor. Conditioned media from BHV-1 infected BBE cells activated bovine PMNs in vitro as demonstrated by PMN shape change, production of reactive oxygen species and degranulation. PMNs also exhibited increased LFA-1 expression and susceptibility to M. haemolytica LKT following incubation with BHV-1 infected BBE cell conditioned media. Our results suggest that BHV-1 infection of BBE cells triggers cytokine expression that contributes to the recruitment and activation of neutrophils, and amplifies the detrimental effects of M. haemolytica LKT.  相似文献   

14.
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15.

Background

Methicillin resistant Staphylococcus pseudintermedius (MRSP) and Staphylococcus aureus (MRSA) are common multi-drug resistant (MDR) bacteria in dogs. In 2012–2013 three dogs of the Guide Dog School of the Finnish Federation of the Visually Impaired were found to be MRSP positive. Guide dogs have regular contact with each other during their first year of life and prolonged contact when in training. Since dogs are placed in different parts of Finland after training, there is a risk for national spread of MDR bacteria. In this study the prevalence of MRSP and MRSA, as well as the risk factors for MRSP were determined in the Finnish guide dog population. MRSP isolates were investigated using molecular methods and compared to the earlier isolates.

Results

Out of 132 tested dogs 4 were MRSP positive thus giving the prevalence estimate of 3% (95% CI: 1–8%) for MRSP in the target population. MRSA was not detected (prevalence estimate 0%, 95% CI: 0–3%). Risk factors associated with MRSP were being a breeding bitch (OR = 8.4; 95% CI: 1.1–64.1, P = 0.012), the number of veterinary visits (OR = 1.23; 95% CI: 1.0–1.5, P = 0.025) and number of antimicrobial courses (OR = 1.63; 95% CI: 1.0–2.55; P = 0.035). Identified MRSP isolates belonged to five different sequence types (ST45, 71, 402, 403 and 404). All ST71 isolates carried SCCmec II-III, while the SCCmec type of the ST45 and ST402 (a single locus variant of ST45) isolates were non-typeable with the method used.

Conclusions

MRSP and MRSA had low prevalence in the studied dog population despite the close contact between dogs, and the MRSP population was heterogenic. Antimicrobial therapy and veterinary visits are risk factors for MRSP even among a small case group.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-015-0129-8) contains supplementary material, which is available to authorized users.  相似文献   

16.
The sensitivity of some porcine and bovine mycoplasmas to potent antimicrobial agents was examined. Minimal inhibitory concentration (MIC) values were estimated for M. hyosynoviae, M. hyopneumoniae, M. dispar and M. bovis against enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, in a liquid medium test and in a disc assay. All 6 examined strains of each species and the respective type strains were significantly inhibited. The greatest sensitivity was noted for tiamulin against strains of M. hyosynoviae with a final MIC50 broth value of 0.025 µg ml−1 and disc value of 0.03 µg per disc. Enrofloxacin was found very potent against M. hyopneumoniae with a final MIC50 of 0.025 µg ml−1 and 0.1 µg per disc, and for M. dispar with 0.05 µg ml−1 and 0.03 µg per disc.Most disc assay estimates in ug per disc were similar to or moderately greater than corresponding final broth figures in µg ml−1. It may be possible to convert observed disc assay values into representative final broth MIC values for use in the clinic.  相似文献   

17.
This study was conducted to determine the effect of necrotic enteritis (NE), phytase level and meat and bone meal (MBM) processing on bone mineralization of broilers and litter quality. Ross 308 male broiler chicks (n = 768) were allotted to 48 pens with 16 birds each. There were 8 dietary treatments in a 2 × 2 × 2 factorial arrangement. Factors were NE challenge (no or yes), phytase level (500 or 5,000 FTU/kg), and MBM (as-received or over-processed). Half of the birds were challenged with field strains of Eimeria spp. at d 9 and 108 CFU per mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15. The middle toe, tibia and femur of 2 birds per pen were excised at d 16 and 29 for determination of ash, breaking strength (BS) and bone mineralization. At d 42, all were assessed for hock burns and litter was scored and assessed for dry matter (DM). At d 16, challenged birds had lower toe ash (P < 0.01), femur ash (P < 0.001), tibia ash (P < 0.001) and tibial BS (P < 0.001) than unchallenged birds. At d 16, challenged birds fed high phytase and over-processed MBM had higher toe Mn than those fed low phytase and as-received MBM. At d 29 unchallenged birds fed high phytase and as-received MBM had a higher toe Mn than those fed over-processed MBM. At d 16, a phytase × MBM interaction was detected for femur Zn concentration (P < 0.05), where a higher level of Zn was observed in the high phytase group fed over-processed MBM. At d 16, tibial Ca (P < 0.05) and P (P < 0.05) were lower in the challenged whereas the femur K (P < 0.001), Mn (P < 0.01) and Na (P < 0.001) were higher in the challenged at d 16. At d 42, challenged birds had higher litter DM (P = 0.058) and fewer hock burns than those unchallenged (P < 0.05). In conclusion, NE impaired bone traits but high phytase and over-processed MBM increased bone mineral contents. Cases of hock burns may be lower under NE incidences due to lower livability of birds reducing litter wetness.  相似文献   

18.
The objective of this study was to investigate the effects of supplementing N-carbamoylglutamate (NCG), an Arg enhancer, on amino acid (AA) supply and utilization and productive performance of early-lactating dairy cows. Thirty multiparous Chinese Holstein dairy cows were randomly divided into control (CON, n = 15) and NCG (CON diet supplemented with NCG at 20 g/d per cow, n = 15) groups at 4 wk before calving. Diets were offered individually in tie-stalls, and NCG was supplemented by top-dress feeding onto total mixed ration for the NCG group. The experiment lasted until wk 10 after calving. Dry matter intake tended to be higher (P = 0.06), and yields of milk (P < 0.01), milk protein (P < 0.01), and milk fat (P < 0.01) were higher in the NCG-cows than in the CON-cows. Plasma activities of aspartate aminotransferase (P < 0.01), alanine aminotransferase (P = 0.03), and plasma level of β-hydroxybutyrate (P = 0.04) were lower in the NCG-cows than in the CON-cows, whereas plasma glucose (P = 0.05) and nitric oxide (NO, P < 0.01) concentrations were higher. Coccygeal vein concentrations of Cys (P < 0.01), Pro (P < 0.01), Tyr (P = 0.05), most essential AA except Thr and His (P < 0.01), total essential AA (P < 0.01), and total AA (P < 0.01) were higher in the NCG-cows than in the CON-cows. The arterial supply of all AA was greater in the NCG-cows than in the CON-cows. The NCG-cows had higher mammary plasma flow of AA (P = 0.04) and clearance rate of Cys (P < 0.01), Pro (P < 0.01) and Asp (P < 0.01), and higher ratios of uptake to output of Met (P = 0.05), Lys (P < 0.01), Cys (P = 0.01), Pro (P = 0.03), and Asp (P = 0.01). In summary, addition of NCG initiated from the prepartum period improved the lactation performance of postpartum dairy cows, which might attribute to greater Arg and NO concentrations, as well as improved AA supply and utilization, liver function, and feed intake in these cows.  相似文献   

19.
Two studies were conducted to investigate the effect of Bacillus amyloliquefaciens CECT 5940 (BA) as a probiotic on growth performance, amino acid digestibility and bacteria population in broiler chickens under a subclinical necrotic enteritis (NE) challenge and/or fed diets with different levels of crude protein (CP). Both studies consisted of a 2 × 2 factorial arrangement of treatments with 480 Ross 308 mix-sexed broiler chickens. In study 1, treatments included 1) NE challenge (+/−), and 2) BA (1.0 × 106 CFU/g of feed) supplementation (+/−). In study 2, all birds were under NE challenge, and treatments were 1) CP level (Standard/Reduced [2% less than standard]) and 2) BA (1.0 × 106 CFU/g of feed) supplementation (+/−). After inducing NE infection, blood samples were taken on d 16 for uric acid evaluation, and cecal samples were collected for bacterial enumeration. In both studies, ileal digesta was collected on d 35 for nutrient digestibility evaluation. In study 1, the NE challenge reduced body weight gain (BWG), supressed feed conversion ratio (FCR) and serum uric acid levels (P < 0.001). Supplementation of BA increased BWG (P < 0.001) and reduced FCR (P = 0.043) across dietary treatments, regardless of challenge. Bacillus (P = 0.030) and Ruminococcus (P = 0.029) genomic DNA copy numbers and concentration of butyrate (P = 0.017) were higher in birds fed the diets supplemented with BA. In study 2, reduced protein (RCP) diets decreased BWG (P = 0.010) and uric acid levels in serum (P < 0.001). Supplementation of BA improved BWG (P = 0.001) and FCR (P = 0.005) and increased Ruminococcus numbers (P = 0.018) and butyrate concentration (P = 0.033) in the ceca, regardless of dietary CP level. Further, addition of BA reduced Clostridium perfringens numbers only in birds fed with RCP diets (P = 0.039). At d 35, BA supplemented diets showed higher apparent ileal digestibility of cystine (P = 0.013), valine (P = 0.020), and lysine (P = 0.014). In conclusion, this study suggests positive effects of BA supplementation in broiler diets via modulating gut microflora and improving nutrient uptake.  相似文献   

20.
The present study aimed to investigate whether inflammation-associated responses in piglets are induced by high protein (HP) through activating nuclear factor kappa B (NF-κB) signaling. Sixteen piglets (35 d of age, Duroc × [Landrace × Yorkshire], weaned at d 21, initial BW = 9.70 ± 0.11 kg) were allocated to 18% and 26% CP (HP group) at random, comprising 8 replicate pens per treatment. The piglets were slaughtered to collect intestinal tissues when apparent, persistent, and stable diarrhea syndromes happened (on d 12). No significant differences were observed in their growth performance (P > 0.05), but reduction by 19.11%, 25.31%, 23.64% of ADFI, ADG, and G:F, respectively was detected in the HP group. The HP group had greater (P = 0.002) diarrhea rates. Furthermore, dietary HP had lower ileal villus height (VH; P = 0.048), ratio of villus height to crypt depth (VH/CD ratio; P = 0.016), and colonic CD (P = 0.034), as well as had the trend (P = 0.075) to reduce the ileal villus absorptive area. Moreover, HP diets significantly elevated the goblet cell numbers in the ileal villi (P = 0.016) and colonic crypts (P < 0.001) and up-regulated (P = 0.012) the mRNA expression of mucin2 (Muc2) in the ileum. In addition, HP diets increased the myeloperoxidase concentration in the ileum (P = 0.002) and colon (P = 0.007) of piglets. Dietary HP significantly down-regulated the mRNA expression of tumor necrosis factor-α (TNF-α; P < 0.001) in the ileum, induced nitric oxide synthase (iNOS; P = 0.040) and interleukin-22 (IL-22; P = 0.008) in the colon, and inclined to down-regulate interleukin-1β (IL-1β; P = 0.076) expression in the colon. The relative protein abundance of Galectin-3 (P = 0.046) in the colon and the ratio of phosphorylation NF-κB to NF-κB (p–NF–κB/NF-κB ratio) in the ileum of HP piglets were also greater (P = 0.038). These results suggest that dietary HP may cause diarrhea in piglets by activating NF-κB signaling induced intestinal inflammation.  相似文献   

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