Development of an experimental model for liver abscess induction in Holstein steers using an acidotic diet challenge and bacterial inoculation.

Holstein steers (n = 40; initial BW = 84.9 ±â€…7.1 kg) were used to study the genesis of liver abscesses (LA) using an acidotic diet challenge with or without intraruminal bacterial inoculation. Steers were housed in individual pens inside a barn and randomly assigned to one of three treatments: (1) low-starch control diet comprised primarily of dry-rolled corn and wet corn gluten feed (CON); (2) high-starch acidotic diet with steam-flaked corn (AD); or (3) acidotic diet plus intraruminal inoculation with Fusobacterium necrophorum subsp. necrophorum (9.8 × 108 colony forming units [CFU]/mL), Trueperella pyogenes (3.91 × 109 CFU/mL), and Salmonella enterica serovar Lubbock (3.07 × 108 CFU/mL), previously isolated from LA (ADB). Steers in AD and ADB were fed the acidotic diet for 3 d followed by 2 d of the CON diet, and this cycle was repeated four times. On day 23, ADB steers were intraruminally inoculated with the bacteria. At necropsy, gross pathology of livers, lungs, rumens, and colons was noted. Continuous data were analyzed via mixed models as repeated measures over time with individual steer as the experimental unit. Mixed models were also used to determine the difference in prevalence of necropsy scores among treatments. Ruminal pH decreased in AD and ADB steers during each acidotic diet cycle (P ≤ 0.05). LA prevalence was 42.9% (6 of 14) in ADB vs. 0% in AD or CON treatments (P < 0.01). Ruminal damage was 51.1% greater in ADB than in AD (P ≤ 0.04). Culture of LA determined that 100% of the abscesses contained F. necrophorum subsp. necrophorum, 0% contained T. pyogenes, 50% contained Salmonella, and 50% contained a combination of F. necrophorum subsp. necrophorum and Salmonella. The F. necrophorum subsp. necrophorum was clonally identical to the strain used for the bacterial inoculation based on phylogenetic analysis of the whole genome. This experimental model successfully induced rumenitis and LA in Holstein steers and confirms the central dogma of LA pathogenesis that acidosis and rumenitis lead to the entry of F. necrophorum into the liver to cause abscesses. Our findings suggest that an acidotic diet, in conjunction with intraruminal bacterial inoculation, is a viable model to induce LA. Further research is needed to determine the repeatability of this model, and a major application of the model will be in evaluations of novel interventions to prevent LA.

Liver abscesses (LA) in feedlots are costly to the beef industry. At harvest, LA cause an increase in liver condemnations, carcass trimming, and a decrease in quality grade. The objective of this research was to develop an experimental LA model in Holstein steers using an acidotic diet with and without intraruminal inoculation of bacteria involved in LA formation. These data suggest acidotic diet challenges in conjunction with bacterial inoculation were able to induce LA in Holstein steers. The acidotic diet alone caused reduced rumen content pH and caused rumen wall inflammation and damage, observed at harvest. Nonetheless, the addition of bacteria had a compounding effect on rumen damage. Both bacteria inoculated were isolated from 57% of LA suggesting they may work in synergy to form LA.

Isolation and genomic characterization of Staphylococcus aureus bacteriophages from Chennai, India.

We isolated and characterized two lytic bacteriophages against Staphylococcus aureus named TANUVAS_MVC-VPHSA1 and TANUVAS_MVC-VPHSA2, with the aim of investigating their genomic and structural features. The bacteriophages belong to the Caudoviricetes, and their genomes have sizes of 50,505 and 50,516 base pairs with a GC content of 41.4%.

Impact of In-Feed versus In-Water Chlortetracycline and Tiamulin Administrations on Fecal Prevalence and Antimicrobial Susceptibilities of Campylobacter in a Population of Nursery Pigs.

Antimicrobial resistance (AMR) in bacteria is a major public health concern in the US and around the world. Campylobacter is an important foodborne pathogen that resides in the gut of pigs and is shed in feces, with the potential to be transmitted to humans. In pigs, the oral route, either in-feed or in-water, is by far the most common route of administration of antimicrobials. Because the distribution of the antibiotic in the gut and the dosages are different, the impact of in-feed vs. in-water administration of antibiotics on the development of AMR is likely to be different. Therefore, a study was conducted to compare in-feed vs. in-water administrations of chlortetracycline (CTC) and/or tiamulin on fecal prevalence and AMR profiles of Campylobacter among weaned nursery piglets. A total of 1,296 weaned piglets, allocated into 48 pens (27 piglets per pen), were assigned randomly to six treatment groups: Control (no antibiotic), in-feed CTC, in-water CTC, in-feed tiamulin, in-water tiamulin, or in-feed CTC and tiamulin. Fecal samples were collected randomly from 5 piglets from each pen during the pre-treatment (days 0, 7), treatment (days 14, 21), and post-treatment (days 28, 35) phases. Bacterial isolations and species identifications were conducted by culture and PCR, respectively. The microbroth dilution method with SensititreTM plates was used to determine the antimicrobial susceptibility and resistance of Campylobacter isolates. The results on resistance were interpreted based on the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cutoff values for Campylobacter. The overall prevalence of Campylobacter was 18.2% (262/1440). Speciation of Campylobacter isolates by PCR indicated the prevalence of only two species: Campylobacter hyointestinalis (17.9%; 258/1440) and C. coli (0.3%; 4/1440). Campylobacter isolates were resistant to tetracycline (98.5%), ciprofloxacin (89.3%), and nalidixic acid (60.3%). Neither the antibiotic nor the route of administration had an effect (p > 0.05) on the prevalence of AMR Campylobacter in the feces of piglets.

Barium Lanthanum Oxide Nanosheets in Photocatalytic and Forensic Applications: One-Pot Synthesis and Characterization.

The present work elucidates the fabrication of Barium Lanthanum Oxide nanosheets (BaLa2O4 NSs) via a simple one-pot precipitation method. The acquired results show an orthorhombic crystal system with an average crystallite size of 27 nm. The morphological studies revealed irregular-shaped sheets stacked together in a layered structure, with the confirmation of the precursor elements. The diffused reflectance studies revealed a strong absorption between 200 nm and 350 nm, from which the band-gap energy was evaluated to be 4.03 eV. Furthermore, the fluorescence spectrum was recorded for the prepared samples; the excitation spectrum shows a strong peak at 397 nm, attributed to the 4F7/2→4G11/2 transition, while the emission shows two prominent peaks at 420 nm (4G7/2→4F7/2) and 440 nm (4G5/2→4F7/2). The acquired emission results were utilized to confirm the color emission using a chromaticity plot, which found the coordinates to be at (0.1529 0.1040), and the calculated temperature was 3171 K. The as-prepared nanosheets were utilized in detecting latent fingerprints (LFPs) on various non-porous surfaces. The powder-dusting method was used to develop latent fingerprints on various non-porous surfaces, which resulted in detecting all the three ridge patterns. Furthermore, the as-synthesized nanosheets were used to degrade methyl red (MR) dye, the results of which show more than 60% degradation at the 70th minute. It was also found that there was no further degradation after 70 min. All the acquired results suggest the clear potential of the prepared BaLa2O4 NSs for use in advanced forensic and photocatalytic applications.

Prevalence and Characterization of Staphylococcus aureus Isolated from Retail Raw Milk Samples in Chennai, India.

Milk is an important source of food, and it is also a nutrient-rich medium, which can harbor multiple microorganisms. Staphylococcus aureus is an important foodborne pathogen in food-producing animals, and there have been many reports on its infection and antimicrobial resistance (AMR), which has significant global public health concerns. This study was designed to isolate, characterize, and analyze the AMR pattern of S. aureus from milk samples collected in Chennai, India. A total of 259 raw milk samples from 3 groups: dairy farms, local vendors, and retail outlets were analyzed, and it was found that 34% (89/259) were positive for S. aureus. Positive isolates were further characterized by pulsed-field gel electrophoresis and isolates recovered from different sources, study areas, and locations showed high genetic diversity with no similarity. The presence of AMR has been further assessed by phenotypic methods as per CLSI-M100 performance standards, and all the isolates were susceptible to ampicillin/sulbactam, mupirocin, and tylosin. Additionally, all of the isolates were resistant to ampicillin. There were 28 isolates categorized as multidrug-resistant, which showed resistance to more than 2-3 classes of antimicrobials. This is the first report of inducible clindamycin resistance and mupirocin sensitivity pattern from S. aureus isolates recovered from milk. This study established the occurrence varied with genetic diversity in the isolates prevalent in the study area and divergence pattern of AMR S. aureus. The AMR in these isolates and with methicillin-resistant S. aureus could pose a serious threat to food safety and economic implications.

Evaluation of a Lactococcus lactis-based dried fermentation product administered through drinking water on nursery pig growth performance, fecal Escherichia coli virulence genes and pathotypes, antibiotic usage, and mortality.

A total of 34,749 pigs were used in two experiments to evaluate the effects of a postbiotic dried fermentation product (DFP) administered through drinking water on nursery pig growth performance, antibiotic injection frequency, morbidity, mortality, fecal consistency, and characterization of fecal Escherichia coli. The DFP is composed of bioactive molecules derived from Lactococcus lactis. In Exp. 1, 350 barrows (DNA Line 200 × 400; initial body weight [BW] 6.1 ± 0.01 kg) were used in a 42-d study with five pigs per pen and 35 pens per treatment. The DFP was supplied for 14 d at a target dosage of 24 mg/kg BW using a water medicator at a 1:128 dilution. On days 7 and 14, fecal samples were collected for dry matter (DM) and to determine, by a multiplex polymerase chain reaction (PCR) assay, prevalence of 11 virulence genes characteristic of E. coli pathotypes. There was no evidence (P > 0.10) for differences for growth, incidence of diarrhea, number of antibiotic injections, removals, or fecal DM. On both fecal collection days, E. coli virulence genes were present with day 7 samples positive for genes that encode for hemolysins (hlyA, exhA), intimin (eae), and enteroaggregative heat-stable enterotoxin (astA). Prevalence of enterotoxin genes (elt, estA, estB, astA) increased on day 14, but DFP had no effects on the prevalence of any of the virulence genes. A total of 32 out of 72 E. coli isolates were identified as enterotoxigenic pathotype and all except one were from day 14 fecal samples. Fourteen isolates were positive for F4 fimbria and one isolate was positive for F4 and F18 fimbriae. In Exp. 2, 34,399 nursery pigs (initially 5.6 kg) were used in 20 nursery barns with 10 barns per treatment (control or DFP). The target dosage of the DFP for the first 14 d was 35 mg/kg BW. Following the 14-d supplementation period, pigs continued to be monitored for approximately 31 d. There was no evidence (P > 0.05) for the DFP to influence the overall percentage of pigs that died or growth performance. From days 0 to 14, providing the DFP reduced (P < 0.05) the percentage of pigs that were euthanized. However, providing the DFP increased (P < 0.05) the overall percentage of pigs that were euthanized and total mortality. For the number of antibiotic injections (treatment interventions), providing the DFP reduced the number of injections for the common period (P < 0.001) and overall (P = 0.002). These results indicate that the DFP did not influence growth performance but providing the DFP in Exp. 2 led to increased total nursery pig mortality.

Short communication: evaluation of an endotoxin challenge and intraruminal bacterial inoculation model to induce liver abscesses in Holstein steers.

Holstein steers (n = 40; initial body weight [BW] = 96.0 ± 10.5 kg) were individually housed in a climate-controlled barn to evaluate potential models for the genesis of liver abscesses (LA). In this 2 × 2 factorial, steers were balanced by BW and randomly assigned to one of two treatments: 1) intravenous saline injection followed by intraruminal bacterial inoculation with Fusobacterium necrophorum subsp. necrophorum (1 × 109 colony forming unit [CFU]/mL) and Salmonella enterica serovar Lubbock (1 × 106 CFU/mL; CON; n = 20 steers); or 2) intravenous injection with 0.25 µg/kg BW of lipopolysaccharide (LPS; Escherichia coli O111:B4) followed by intraruminal bacterial inoculation of F. necrophorum subsp. necrophorum (1 × 109 CFU/mL) and S. enterica serovar Lubbock (1 × 106 CFU/mL; LBI; n = 20 steers) and 1 of 2 harvest dates (3 or 10 d post LPS infusion). Body weights were recorded on days -4, -1, 3, and 10, and blood was collected for hematology on days -4, 3, and 10, relative to LPS infusion on day 0. Intraruminal bacterial inoculation occurred on day 1. Steers from each treatment group were harvested at two different time points on day 3 or 10 to perform gross pathological examination of the lung, rumen, liver, LA (if present), and colon. Feed disappearance was less for LBI than CON (P < 0.01); however, BW did not differ (P = 0.33) between treatments. Neither treatment nor time differed for hematology (P ≥ 0.13), and no gross pathological differences were noted in the lung, liver, LA, or colon (P ≥ 0.25). A treatment × harvest date interaction was noted for ruminal pathology in which LBI had an increased percentage of abnormal rumen scores on day 3 (P < 0.01). These results suggest that an LPS challenge in combination with intraruminal bacterial inoculation of pathogens commonly isolated from LA was not sufficient to induce LA in steers within 3 or 10 d (P = 0.95) when compared to CON. Further evaluation is needed to produce a viable model to investigate the genesis and prevention of LA in cattle.

Liver abscesses in feedlot cattle can cause a decrease in feed intake, average daily gain, feed efficiency, and hot carcass weight. At harvest, liver abscesses result in liver condemnations, carcass trimming, and a potential decrease in quality grade, with an estimated economic cost to packers of $41.6 million annually. Our objective was to evaluate an intravenous endotoxin challenge followed by intraruminal inoculation of bacteria commonly isolated from liver abscesses over a 10-d period as a potential model to understand the genesis and etiology of liver abscesses in cattle and evaluate possible preventative interventions. Results suggest that an endotoxin challenge in combination with intraruminal bacterial inoculation is not a viable model to induce liver abscesses in steers, and bacterial inoculation alone was insufficient to induce liver abscesses. The length of time necessary to induce liver abscesses is also unknown. Based on our results, more research is needed to develop a noninvasive model to induce liver abscesses in cattle.

Draft Genome Sequence of a Pasteurella multocida Strain Isolated from a Spotted Deer (Axis axis) in India.

Here, we report the genome sequence of a Pasteurella multocida strain isolated from the heart blood of a spotted deer (Bareilly, India). The 2.44-Mbp genome has 2,227 coding sequences, with a G+C content of 40.7%.

Pectin/PVA and pectin-MgO/PVA films: Preparation, characterization and biodegradation studies.

There is a great demand to replace non-renewable materials with eco-friendly renewable materials for many applications in recent times. In the present study, such an attempt was made to substitute synthetic polymer-based films used for food packaging applications with films prepared out of renewable materials derived from waste. The pectin/polyvinyl alcohol (PP) and pectin-MgO/polyvinyl alcohol (PMP) films were prepared and characterized to ascertain their suitability for packaging applications. To improve the mechanical strength and thermal stability of films, MgO nanoparticles were incorporated in situ into the polymer matrix. The pectin used in the study was extracted from citrus fruit peel. The prepared nanocomposite films were evaluated for physico-mechanical properties, water contact angle, thermal stability, crystallinity, morphology, compositional purity and biodegradability. The elongation at break for PP film was 42.24% and for PMP film it was 39.18%. Also, the ultimate modulus in terms of MPa for PP film was 6.8 and for PMP it was 7.9. So, it was found that PMP films have better ductility and modulus than PP films due to the presence of MgO nanoparticles. The spectral studies confirmed the compositional purity of the prepared films. The biodegradation studies revealed that both films could be degraded at ambient conditions at appreciable time span, suggesting them to be a better choice as an environmentally friendly food packaging material.

Encapsulated Co-ZnO nanospheres as degradation tool for organic pollutants: Synthesis, morphology, adsorption and photo luminescent investigations.

Zinc oxide (ZnO) nanostructures, both undoped and Co-doped, were synthesized through the solution combustion process. The diffraction patterns from powder XRD revealed that the materials were crystalline. The morphology of the spherically formed nanoparticles was visualized in SEM micrographs. FTIR spectra verified the existence of a defect-associated peak in Co-encapsulated ZnO (Zn0.98Co0.02O) NPs. Photoluminescence studies are undertaken. Malachite Green (MG) dye is used as a representative organic pollutant to study the adsorptive degradation of Co-doped ZnO nanomaterial. Moreover, the adsorption properties, including isotherm and kinetics, are investigated by analyzing the degradation of MG dye. Experimental parameters, such as the concentration of the MG dye, dosage and pH, were varied to ascertain favorable conditions for the degradation study. The results indicate that the MG dye is 70% degraded. After Co-doping, near-band edge emission in undoped ZnO changed into intense red defect emission and was directly correlated with changes in PL emission.

Effects of Core Antigen Bacterin with an Immunostimulant on Piglet Health and Performance Outcomes When Challenged with Enteric and Respiratory Pathogens.

A total of 90 pigs, approximately one day of age, were used in a 42-day study to evaluate whether Endovac-Porci, a core antigen vaccine with an immunostimulant, provides piglets with broad-spectrum protection against the enteric and respiratory effects of Gram-negative bacteria. This study was a single-site, randomized, prospective, blinded, comparative placebo-controlled design. Individual pigs were randomly allocated to 1 of 2 treatments in a randomized design. An individual pig was considered the experimental unit for the farrowing phase (Study day 0 to 21), and the pen was considered the experimental unit for the nursery phase (Study day 21 to 42). Thus, there were 45 replications per treatment during the farrowing phase and 15 replications per treatment during the nursery phase. Treatments included a control product (saline; CP) and an investigational product (Endovac-Porci; IVP). On Study day 23, all pigs were challenged with enterotoxigenic Escherichia coli strain expressing K88 (F4) fimbriae and Pasteurella multocida. Individual pigs were weighed and feed consumption was measured to determine body weight gain, average daily gain, and feed-to-gain ratio. Clinical and fecal scores and overall health were recorded daily. Overall, administering the IVP to pigs led to an increase (p < 0.01) in body weight gain and average daily gain compared to pigs administered the CP. Pigs administered the IVP had reduced (p < 0.01) mortality compared to pigs administered the CP. There was a Study day × treatment interaction on clinical and fecal scores (p < 0.01). There was also a main effect of Study day where clinical and fecal scores increased (p < 0.01) as the Study day increased. Treatment also had an effect on clinical and fecal scores, where pigs administered the IVP had lower (p < 0.01) clinical and fecal scores compared to pigs administered the CP. In conclusion, administering pigs with the Endovac-Porci vaccination significantly improved the performance (i.e., body weight, body weight gain, and average daily gain) and health (i.e., clinical and fecal scores), while reducing the overall mortality in pigs challenged with E. coli K88 orally and Pasteurella multocida intranasally post-weaning. Results from this study suggest that Endovac-Porci could provide broad-spectrum protection against enteric and respiratory effects of Gram-negative bacteria in piglets.

Evaluation of codon usage patterns and molecular evolution dynamics in Japanese encephalitis virus: An integrated bioinformatics approach.

In the recent survey, Japanese encephalitis (JE) is one of the most common mosquito-borne diseases, accounting for ∼30% of fatalities. The outbreaks of the JE virus (JEV) suggests that exhaustive study is essential for the prevention and management of the disease. The disease mainly spreads in humans and pigs by the vector: mosquito; as this is a major concern, this study had employed various bioinformatics tools to investigate the codon usage bias, evolutionary inference and selection pressure analysis of the Japanese encephalitis virus disease. The results indicated that the JE virus was biased and natural selection was the main factor shaping the codon usage that was determined and confirmed with the Nc, neutrality, PR2 plots and correlation analysis. The evolutionary analysis revealed that the virus had a substitution rate of 1.54 × 10-4 substitution/site/year and the tMRCA was found to be in 1723. The transmission of the virus in the map found transmissions mostly from China and transmitted across Asia and Africa. The selection pressure analysis employed three methods which had 969th codon site as diversifying site and had many purifying sites that shows the virus had evolved rapidly. The inferences from this study would aid people to employ this methodology on various diseases and also perform insilico studies in the field of vaccinology and immunoinformatics.

Evaluating the Antimicrobial and Anti-Hemolytic Activity of Synthesized Pseudopeptide against Leptospiral Species: In Silico and In Vitro Approach.

Bacterial infections are one of the leading causes of morbidity, mortality, and healthcare complications in patients. Leptospirosis is found to be the most prevalent, re-emergent, and neglected tropical zoonotic disease worldwide. The adaptation to various environmental conditions has made Leptospira acquire a large genome (~4.6 Mb) and a complex outer membrane, making it unique among bacteria that mimic the symptoms of jaundice and hemorrhage. Sph2 is another important virulence factor that enhances hemolytic sphingomyelinase-capable of moving inside mitochondria-which increases the ROS level and decreases the mitochondrial membrane potential, thereby leading to cell apoptosis. In the present study, 25 suspected bovine serum samples were subjected to the Microscopic Agglutination Test (MAT) across the Mysuru region. Different samples, such as urine, serum, and aborted materials from the confirmed MAT-positive animals, were used for isolation and genomic detection by conventional PCR targeting virulence gene, Lipl32, using specific primers. Further, in vitro and in silico studies were performed on isolated cultures to assess the anti-leptospiral, anti-hemolytic, and sphingomyelinase enzyme inhibition using novel pseudopeptides. The microdilution technique (MDT) and dark field microscope (DFM) assays revealed that at a concentration of 62.5 µg/mL, the pseudopeptide inhibited 100% of the growth of Leptospira spp., suggesting its efficiency in the treatment of leptospirosis. The flow cytometry analyses show the potency of the pseudopeptide against sphingomyelinase enzymes using human umbilical vein endothelial cells (HUVECs). Thus, the present study demonstrated the efficacy of the pseudopeptide in the inhibition of the growth of Leptospira, and therefore, this can be used as an alternative drug for the treatment of leptospirosis.

Metabolome of purulent materials of liver abscesses from crossbred cattle and Holstein steers fed finishing diets with or without in-feed tylosin.

Liver abscesses in feedlot cattle are a polymicrobial infection with Fusobacterium necrophorum and Trueperella pyogenes as the primary and secondary etiologic agents, respectively. Cattle with liver abscesses do not exhibit clinical signs and the abscesses are detected only at slaughter. The objective was to conduct metabolomics analysis of purulent materials of liver abscesses to identify biochemicals. Liver abscesses from crossbred cattle (n = 24) and Holstein steers (n = 24), each fed high-grain finishing diet with tylosin (n = 12) or no tylosin (n = 12), were included in the study. Abscess purulent materials were analyzed by ultrahigh-performance liquid chromatography-tandem mass spectroscopy. A total of 759 biochemicals were identified and were broadly categorized into carbohydrates, energy metabolism pathways intermediates, peptides, amino acids and their metabolites, lipids and their metabolites, nucleotides, vitamins and cofactors, xenobiotics, and partially characterized molecules. The top 50 biochemicals identified included amino acids, lipids, nucleotides, xenobiotics, peptides, and carbohydrates and their metabolites. Among the 15 amino acid metabolites in the top 50 biochemicals, four were tryptophan metabolites, indoleacrylate, indolepropionate, tryptamine, and anthranilate. The 3-phenylpropionate, a product of phenylalanine metabolism, was the predominant metabolite in purulent materials. Between the four treatment groups, a two-way ANOVA analysis identified biochemicals that exhibited significant main effects for cattle type and in-feed tylosin use and their interactions. A total of 59 and 85 biochemicals were different (P < 0.05) between the cattle type (crossbred vs. Holstein steers) and in-feed tylosin use (tylosin vs. no tylosin), respectively. Succinate, an intermediate of lactate fermentation by some bacterial species, was one of the top 30 biochemicals that differentiated the four treatment groups. A number of lysophospholipids, indicative of bacterial and host cell membrane lyses, were identified in the purulent materials. In conclusion, to our knowledge this is the first report on the metabolome of liver abscess purulent materials and several biochemicals identified were related to metabolic activities of the bacterial community, particularly F. necrophorum and T. pyogenes. Biochemicals unique to liver abscesses that appear in the blood may serve as biomarkers and be of diagnostic value to detect liver abscesses of cattle before slaughter.

Liver abscesses in feedlot cattle, a consequence of feeding a diet of high-grain and low-roughage, are a mixed bacterial infection with Fusobacterium necrophorum, a ruminal bacterium as the primary causative agent. Cattle with liver abscesses do not exhibit clinical signs and the abscesses are detected only at slaughter. The study analyzed purulent materials of liver abscesses of feedlot cattle collected at slaughter for biochemical molecules. A total of 759 biochemicals were identified and a majority belonged to biochemical classes of lipids and amino acids and their metabolites. Biochemicals unique to liver abscesses that enter blood circulation may have the potential to be used as biomarkers in cattle with liver abscess before slaughter.

Nasopharyngeal Bacterial Prevalence and Microbial Diversity at First Treatment for Bovine Respiratory Disease (BRD) and Its Associations with Health and Mortality Outcomes in Feedyard Cattle.

Bovine respiratory disease (BRD) is an economically important disease in feedyards influencing both animal welfare and antimicrobial utilization. Major pathogens associated with BRD have been identified in previous research, but little information is available on the relationship between nasopharyngeal microbiota and health outcomes. The objective of this study was to identify potential associations between nasopharyngeal microbiota and antimicrobial resistance patterns of clinical cases that lived or died compared to non-diseased controls. Enrolled animals were subdivided based on clinical disease status and case outcome (subsequent mortality). Deep nasopharyngeal swabs were collected on enrolled animals and submitted for bacterial isolation, antimicrobial susceptibility determination, and metagenomics analysis. Enrolled cattle were represented in three groups: animals at first treatment for BRD that subsequently died (BRDM, n = 9), animals at first treatment for BRD that subsequently lived (BRDL, n = 15), and animals that were never treated for BRD during the feeding phase (CONT, n = 11). Antimicrobial resistance patterns for Pasteurella multocida illustrated cattle in each outcome category had isolates that were pan-susceptible or only showed resistance to oxytetracycline. The relative abundance of species and genera illustrated few differences among the three outcomes. Higher alpha diversity was identified in BRDL compared to CONT at the species level, and both BRDL and BRDM showed increased alpha diversity compared to CONT at the general level. Overall, this work illustrated nasopharyngeal microbiota showed relatively few differences among BRD cases that lived or died compared to animals without BRD.

Efficacy of Two Probiotic Products Fed Daily to Reduce Clostridium perfringens-Based Adverse Health and Performance Effects in Dairy Calves.

Clostridium perfringens is a spore-forming, anaerobic bacterium which produces toxins and exoenzymes that cause disease in calves, especially necro-hemorrhagic enteritis-associated diarrhea often resulting in death. Clostridium infections are currently being treated with antibiotics, but even with the prudent administration of antibiotics, there are significant rates of recurrence. Probiotics, an alternative to antibiotics, are commonly employed to prevent clostridial infections. The objectives of our study were to demonstrate that two commercially available products, when used as daily, direct-fed microbials, are effective in reducing adverse effects of an experimentally induced C. perfringens infection in dairy calves. We conducted a single site efficacy study with masking using a randomized design comprising 10 calves allocated to 3 treatment groups (probiotic 1, probiotic 2, and control). The procedures such as general health scores, body weight, blood samples, and fecal sample collections were done followed by experimental challenge of calves with C. perfringens. Daily feeding of L. animalis LA51 and P. freudenreichii PF24 without or with Bacillus lichenformis CH200 and Bacillus subtilis CH201, before, during and after an oral challenge of C. perfringens significantly reduced the incidence and severity of diarrhea while improving general impression and appearance scores of calves. Most notably, survival of calves in the two probiotic-fed groups was significantly higher than for control calves and further substantiates the potential economic and health benefits of feeding effective probiotics.

Efficacy of Lactobacillus animalis and Propionibacterium freudenreichii-Based Feed Additives in Reducing Salmonella-Associated Health and Performance Effects in Commercial Beef Calves.

Salmonella enterica, which causes typhoid fever, is one of the most prevalent food-borne pathogens. Salmonellosis in cattle can greatly impact a producer's income due to treatment costs, decreased productivity of the herd, and mortality due to disease. Current methods of treatment and prevention for salmonellosis consist of antibiotics and vaccinations, but neither of these options are perfect. Probiotics, categorized as antibiotic alternatives, are living microorganisms that are added to animal feeds in appropriate quantities in order to benefit health and productivity in adult and newborn livestock. The objective of this study was to demonstrate that Lactobacillus animalis and Propionibacterium freudenreichii, when used as a direct-fed microbial, was effective in reducing the adverse effects of experimentally induced Salmonella infection in beef calves. We conducted a single site efficacy study with masking using a randomized design comprising two groups of ten beef calves allocated to two treatment groups (control and probiotic). Procedures such as determining general health scores and body weight and collecting fecal samples were carried out following the experimental challenge of calves with Salmonella Typhimurium. The presence of at least one CFU of bacteria in feces was significantly higher among animals in the control than in the probiotic group, which was higher on days 0 to 7 than on days 8 to 14 (p = 0.012). Animals in the control group had a significantly higher presence of abnormal diarrhea scores than animals in the probiotic group (p < 0.001). Most notably, other health benefits in probiotic-fed group calves were obviously better than those for control calves and further substantiates the potential economic and health benefits of feeding effective probiotics.

A Facile Synthesis of Cellulose Nanofibers from Corn Cob and Rice Straw by Acid Hydrolysis Method.

Agricultural residues are suitable to make useful products that can potentially replace the non-biodegradable polymeric materials. In the present work, corn cob and rice S=straw is quantitatively transformed to cellulose by alkali treatment preceded by bleaching. The obtained cellulose is changed into nanocellulose (NC) by the acid hydrolysis method followed by ultrasonication. Further NC was characterized by FTIR to study its functional regions and XRD for crystallinity. Thermal properties have been studied using TGA/DTA. The surface morphology of nanocellulose was done using SEM and TEM. The obtained results revealed remarkable thermal stability, semi-crystalline and fibrous nature of both corn cob and rice straw. The size of the cellulose is in the nanoscale dimension. This work provides the way to utilize corn cob and rice straw as a more useful raw material for many applications.

Pathogenesis of Liver Abscesses in Cattle.

Liver abscesses are a bacterial infection, which occurs because of entry, via portal vein, of pyogenic bacteria into the hepatic parenchyma. Liver abscesses are a polymicrobial infection; however, Fusobacterium necrophorum, a ruminal bacterium, is the primary etiologic agent. Ruminal acidosis disrupts the protective barrier function of the ruminal epithelium and facilitates entry and colonization of F. necrophorum in the ruminal wall and subsequent entry into the portal circulation. Virulence factors of F. necrophorum contribute to the evasion of host defense mechanisms and cause tissue damage to set up an infection in the liver. The potential role of the hindgut in pathogenesis remains to be investigated.

Antimicrobial and Biological Methods to Control Liver Abscesses.

Antimicrobial products are approved for the control of liver abscesses with varying amounts of data. When compared to negative controls, tylosin has the most data to support a reduction in total (risk ratio 0.34) and severe A+ (risk ratio 0.31) liver abscesses. Due to the reduction in the use of antimicrobials, vaccination to control liver abscess prevalence is intriguing. However, available vaccines do not appear to be effective in controlling the prevalence of liver abscesses, especially when the disease prevalence is high.