Liver abscesses in cattle: A review of incidence in Holsteins and of bacteriology and vaccine approaches to control in feedlot cattle

Citation: Amachawadi, R. G., & Nagaraja, T. G. (2016). Liver abscesses in cattle: A review of incidence in Holsteins and of bacteriology and vaccine approaches to control in feedlot cattle. Journal of Animal Science, 94(4), 1620-1632. doi:10.2527/jas2015-0261Liver abscesses are the primary liver abnormality of feedlot cattle at slaughter. The incidence of liver abscesses is highly variable, but generally ranges from 10% to 20%. The incidence of total and the proportion of severely abscessed livers (A+) are greater in Holsteins fed for beef production and culled dairy cows than in beef breeds. The reason for the greater incidence of liver abscesses in Holstein steers is not known, but one of the reasons is likely because of increased days on feed. The high prevalence in cull cows is likely because no specific intervention, such as use of tylosin in the feed, is approved for use in dairy cows. Liver abscesses are generally a sequela to ruminal acidosis and rumenitis in cattle fed diets high in readily-fermentable carbohydrates and low in roughages; thus, the term "acidosis-rumenitis-liver abscess complex." Liver abscesses are almost always polymicrobial infections with Gram negative anaerobes constituting the predominant flora. Almost all studies have concluded that Fusobacterium necrophorum, a ruminal bacterium, is the primary causative agent and Trueperella (formerly Arcanobacterium) pyogenes is the secondary pathogen. A limited number of studies have been done on the bacterial flora of liver abscesses of culled dairy cows and Holstein feedlot steers. A recent study has reported on isolation of Salmonella from liver abscesses of Holstein cattle. The control of liver abscesses in feedlot cattle has depended on the use of antibiotics, particularly tylosin, in the feed combined with sound nutritional management to minimize occurrence of acidosis and subsequent rumenitis. Although there is no evidence of resistance development in F. necrophorum, the future of tylosin use as a feed additive in feedlot cattle is uncertain. Regardless, beginning January 2017, the use of tylosin in feedlot cattle for the prevention of liver abscesses will be under veterinary oversight. Although tylosin is widely used in the feedlot industry, there is considerable interest in evaluating antibiotic alternatives, such as essential oils and vaccines, to control liver abscesses. Because liver abscess is a bacterial infection and the pathogenicity and virulence factors of F. necrophorum have been studied widely, there have been considerable interest and efforts to develop an efficacious vaccine. The 2 antigens that have been targeted for vaccine production are leukotoxin and outer membrane proteins of F. necrophorum

Lysine degradation by ruminal Fusobacterium necrophorum

Three experiments were conducted to characterize lysine fermentation by Fusobacterium necrophorum, a ruminal bacterium that is known to degrade amino acids. In Experiment 1, 7 strains of Fusobacterium necrophorum were inoculated into media containing lysine (50 mM), lactate (50 mM), or lysine plus lactate (50 mM each) as the major energy substrate to evaluate growth and ammonia production. All strains grew with lysine, lactate, or lactate plus lysine as the primary substrate. When grown with lysine, all strains produced ammonia as an end product, even if lactate was also present. Smaller concentrations of ammonia for medium containing lactate plus lysine when compared with lysine alone indicate that the Fusobacterium strains used lactate as a growth substrate that stimulated utilization of ammonia. In Experiment 2, the 2 strains tested were able to degrade extensively both lysine and glutamic acid. Some evidence was detected for partial utilization for growth of histidine, methionine, and tryptophan by strain A21. In Experiment 3, the minimum inhibitory concentration (MIC) of the antibiotic tylosin was 25 μg/mL when Fusobacterium necrophorum strains A21 and B35 were grown in either lysine or lactate-enriched medium. The MIC of monensin was 6.25 and 3.9 μg/mL for strains A21 and B35, respectively, when grown in lysine-enriched medium, but \u3e 50 and 10.9 μg/mL when the strains were grown in lactate-enriched medium. These findings may lead to ways that ruminal lysine degradation may be controlled.; Dairy Day, 2010, Kansas State University, Manhattan, KS, 2010; Dairy Research, 2010 is known as Dairy Day, 201

Effects of feeding elevated concentration of copper on prevalence and selection of fecal enterococci positive for transferable copper resistance gene in piglets

Master of ScienceDepartment of Diagnostic Medicine/PathobiologyTiruvoor G. NagarajaCopper, as copper sulfate, is often supplemented at elevated concentrations in swine diets, particularly in piglets, to promote growth. Growth promotional effects of copper are believed to be similar to that of antibiotics in that gut microbial flora is altered to reduce loss of nutrients and suppress pathogens. Bacteria exposed to copper may acquire resistance, and in Enterococcus faecium and E. faecalis, resistance is conferred by a plasmid-borne transferable copper resistance (tcrB) gene. The plasmid also carries macrolide [erm(B)] and glycopeptide (vanA) antibiotics resistance genes. The objectives of the research were to 1) determine the prevalence of tcrB gene in fecal enterococci of piglets in relation to normal (16.5 ppm) and elevated level (125 ppm) of copper supplementation, 2) determine the relationship of tcrB gene and susceptibilities to copper, erythromycin, and vancomycin, and 3) determine the transferability of tcrB gene in enterococci by conjugation. Weaned piglets, housed in pens, fed normal (16.5 ppm; control) or elevated level of copper (125 ppm) were used. Fecal samples were collected weekly for isolation of enterococci. Isolates were speciated by multiplex PCR and sodA gene sequence analysis. The prevalence of tcrB-positive enterococcal isolates was higher (P < 0.05) in the copper supplemented group than the control group. The prevalence of tcrB was affected by sampling days (P < 0.05) with a significant treatment and sampling time interaction (P < 0.05). The tcrB positive isolates were either E. faecium or E. faecalis, and majority of isolates was E. faecium. The mean MIC of copper for tcrB-positive isolates (21.1 mM) was higher (P < 0.001) compared to tcrB-negative isolates (6.1 mM). All isolates were resistant to erythromycin, tetracyclines and susceptible to vancomycin. The transferability of the tcrB gene from tcrB-positive strains to tcrB-negative strains was demonstrated by conjugation. The potential link between tcrB and antibiotic resistance genes and the propensity of enterococci to transfer tcrB to other strains suggests the possibility that copper supplementation may exert selection pressure for antibiotic resistance. The positive association between copper supplementation and prevalence of tcrB gene has important implications for antimicrobial resistance and food safety, which warrants further investigation

Intermittent Feeding of Tylan Reduces Use of In-Feed Antibiotics While Still Controlling Incidence of Liver Abscesses in Finishing Steers

Liver abscesses are a cause of concern for many feedlots across the country as they lead to a decrease in feedlot performance of finishing cattle as well as a decrease in the final carcass value. Loss in carcass value is due to not only the abscessed liver being condemned, but also due to trim loss associated with the condemned liver. The macrolide drug tylosin phosphate is the drug of choice for metaphylactic treatment of liver abscesses in feedlot cattle. The Food and Drug Administration approved the drug for over-the-counter use, however, from January 2017 all medically important (used in human health) antibiotics that are to be fed in production animal diets will require a veterinary feed directive. The objective of the veterinary feed directive program is to decrease the use of medically important antibiotics in animal production. These veterinary feed directives are similar to a prescription and will encourage the use of the drug in accordance to FDA-guidelines associated with that drug. Macrolide antibiotics are considered medically important and will need a veterinary feed directive. Therefore, it is imperative to look at different methods to control liver abscesses in feedlot cattle. Various studies have noted that macrolide antibiotics (such as tylosin phosphate) are effective against pathogens for moderate to prolonged periods after initial use. The purpose of this study was to determine whether feeding tylosin phosphate periodically throughout the finishing period will have a comparable effect on decreasing liver abscesses as when we would feed tylosin phosphate continuously through the finishing period

Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

Citation: DeMars, Z., Biswas, S., Amachawadi, R. G., Renter, D. G., & Volkova, V. V. (2016). Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions. Plos One, 11(5). doi:10.1371/journal.pone.0155599Antimicrobial treatments result in the host's enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-TestR following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: ?-lactams (specifically, ampicillin and ceftriaxone E-Test1 ), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/ trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n?30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment suggested that during first days in anaerobic conditions the susceptibility changes with time. The results demonstrate that assessing effects of antimicrobial treatments on resistance in the host's enteric bacteria that are Gram negative facultative Anaerobe Bacilli requires data on the bacterial antimicrobial susceptibility in the conditions resembling those in the intestine. © 2016 DeMars et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Supplemental Zinc Sulfate Interacts with Optaflexx in Feedlot Heifers

Optaflexx is a beta-adrenergic agonist, and is fed to cattle during the final 28 to 42 days on feed to improve growth rate and feed efficiency. Beta-adrenergic agonists are repartitioning agents that stimulate muscle deposition at the expense of fat deposition. Zinc is a trace mineral element that functions as an important component of many enzyme systems, including those associated with nucleic acid synthesis and metabolism of proteins and carbohydrates, thus making it an essential nutrient for growth. The purpose of this study was to evaluate growth, carcass characteristics, and plasma urea nitrogen concentrations in finishing heifers supplemented with Optaflexx at 0 or 200 mg/animal daily, in the presence of 30 or 100 ppm supplemental zinc. We hypothesized that feeding Optaflexx could increase requirements for dietary zinc, and that additional zinc supplementation could increase the growth response to Optaflexx

Determination of Probiotic and/or Chlortetracycline Inclusion Effects on Nursery Pig Growth Performance

A total of 300 nursery pigs (DNA 200 × 400, Columbus, NE; initially 13.0 lb BW) were used in a 42-d study evaluating the effects of feeding chlortetracycline (CTC) in combination with probiotics on nursery pig performance. Probiotics are a class of antimicrobial alternatives designed to enhance growth performance and digestive tract health. Pigs were weaned at approximately 21 d of age and allotted to pens based on initial BW. Pigs were fed a common pelleted starter diet for 4 d and then weighed, and pens were allotted to 1 of 6 dietary treatments based on BW in a completely randomized design. The treatments were arranged in a 2 × 3 factorial with main effects of chlortetracycline (0 vs. CTC at 400 g/ton from d 0 to 42) and probiotic (0 vs. 1 lb/ton Bioplus 2B (Chr. Hansen USA, Inc., Milwaukee, WI)) vs. 1 lb/ton Poultry Star (Biomin America, Inc., San Antonio, TX). Experimental diets were fed in 2 phases (Phase 1: d 0 to 14 and Phase 2: d 14 to 42) and fed in meal form. On d 14 and 28, CTC was removed from the diet according to FDA regulations. For overall performance, there were no interactions (P \u3e 0.05) between added probiotics and CTC. However, pigs fed CTC had improved (P \u3c 0.001) ADG, ADFI, and overall BW compared with those fed diets without CTC. While adding Poultry Star to the diet increased (P \u3c 0.05) BW and ADFI on d 14, there were no consistent benefits of feeding either probiotic alone or in combination with CTC

Effects of copper sulfate and zinc oxide on weanling pig growth and plasma mineral levels

A total of 216 weanling pigs (PIC TR4 × 1050, initially 13.6 lb and 21 d of age) were used in a 42-d growth trial to compare the effects of supplemental zinc and copper and changing mineral regimens on growth performance and plasma mineral levels. The 6 dietary treatments included a 2 × 2 factorial arrangement with main effects of added copper from copper sulfate (0 or 125 ppm) and added zinc from zinc oxide (0 or 3,000 ppm from d 0 to 14 and 0 or 2,000 ppm from d 14 to 42). For the final 2 treatments, either zinc oxide alone or the combinations of zinc and copper were fed from d 0 to 14, with copper sulfate fed from d 14 to 42. There were 6 pens per treatment with 6 pigs per pen. All diets were supplemented with an additional 165 ppm zinc and 16.5 ppm copper from the trace mineral premix. Plasma was collected from 2 pigs per pen on d 14 and 42. From d 0 to 14, ADG, ADFI, and F/G were improved (P < 0.04) with the addition of dietary zinc. Copper supplementation also tended to increase (P < 0.07) ADFI from d 0 to 14. From d 14 to 42, added copper increased (P < 0.003) ADG and ADFI. Over the entire trial, continuous supplemental zinc increased (P < 0.03) ADG and tended to increase (P < 0.09) ADFI. Dietary copper also increased (P < 0.004) ADG and ADFI when fed from d 0 to 42. The most advantageous values for ADG and ADFI were seen in the treatment containing high levels of zinc from d 0 to 14 and high copper levels from d 14 to 42. The addition of either zinc or copper increased (P < 0.02) feed cost per pound of gain. However, income over feed cost was improved (P < 0.006) with the addition of copper, with the greatest value obtained when high zinc was fed from d 0 to 14 and high copper was fed from d 14 to 42. Plasma zinc levels were increased (P < 0.001) with zinc supplementation on d 14. These results indicate the optimal mineral regimen was supplementing zinc oxide from d 0 to 14 and copper sulfate from d 14 to 42

Effects of dietary zinc oxide and chlortetracycline on nursery pig growth performance

Swine Industry Day, 2014 is known as Swine Day, 2014A total of 240 weaned pigs (PIC 1050; initially 13.4 lb) were used in a 47-d study to compare the effects of added Zn from zinc oxide (ZnO), alone or in combination with a low or high dose of chlortetracycline (CTC), on nursery pig performance. Pigs were allotted to pens at weaning (d 0) and fed a common starter diet with no antimicrobial for 5 d before the start of the experiment. On d 5, pens of 5 pigs were allotted to 1 of 6 dietary treatments in a randomized complete block design with 8 replications per treatment. Dietary treatments were arranged in a 2 × 3 factorial with main effects of added ZnO (0 vs. 2,500 ppm of Zn) and CTC (0, 50, or 400 g/ton). Pigs were fed experimental diets from d 5 to 26 after weaning followed by a common corn-soybean meal–based diet without antimicrobial from d 26 to 47. Pigs on the 50 g/ton treatment received CTC continuously from d 5 to 26; however, to comply with FDA guidelines, CTC was removed on d 15 from the diets of pigs fed 400 g/ton CTC, then added again from d 16 to 26. All diets contained 110 ppm of Zn from ZnO in the trace mineral premix. No ZnO × CTC interactions were observed. Pigs fed added ZnO had increased (P = 0.001) ADG, ADFI, and ending BW during the treatment period but increased F/G (P = 0.03) from d 26 to 47 when a common diet was fed. Pigs fed CTC had increased (linear, P < 0.05) ADG, ADFI, and ending BW during the treatment period as well as a tendency (quadratic, P = 0.08) for improved F/G. Overall (d 5 to 47), pigs fed added ZnO had increased (P < 0.05) ADG and ADFI. Overall, pigs fed CTC tended to have increased (linear, P = 0.06) ADG and ADFI, but F/G tended (quadratic, P = 0.07) to decrease then increase as CTC increased. In summary, when ZnO or CTC were added to the diets, increased ADG and ADFI were observed, but additional carryover benefits were not evident after these feed additives were removed from the diets. The benefits of added Zn from ZnO and CTC are additive and could be included together in diets to get the maximum benefit in growth performance of weaned pigs

COVID-19 PANDEMIC: A SYSTEMATIC REVIEW ON THE CORONAVIRUSES OF ANIMALS AND SARS-CoV-2

Coronaviruses (CoVs), classified into four genera, viz., alpha-, beta-, gamma-, and Delta- CoV, represent an important group of diverse transboundary pathogens that can infect a variety of mammalian and avian species including humans, animals, poultry, and non-poultry birds. CoVs primarily infect lung and gut epithelial cells, besides monocytes and macrophages. CoVs have high mutation rates causing changes in host specificity, tissue tropism, and mode of virus excretion and transmissions. The recent CoV zoonoses are SARS, MERS, and COVID-19 that are caused by the transmission of beta-CoVs of bats to humans.&nbsp; Recently, reverse zoonoses of the COVID-19 virus have been detected in dogs, tigers, and minks. Beta-CoV strains also infect bovine (BCoV) and canine species (CRCoV); both these beta-CoVs might have originated from a common ancestor. Despite the high genetic similarity between BCoV, CRCoV, and HCoV-OC43, these differ in species specificity. Alpha-CoV strains infect canine (CCoV), feline (FIPV), swine (TGEV and PEDV), and humans (HCoV229E and NL63). Six coronavirus species are known to infect and cause disease in pigs, seven in human beings, and two in dogs. The high mutation rate in CoVs is attributed to error-prone 3′-5′ exoribonuclease (NSP 14), and genetic recombination to template shift by the polymerase. The present compilation describes the important features of the CoVs and diseases caused in humans, animals, and birds that are essential in surveillance of diverse pool of CoVs circulating in nature, and monitoring interspecies transmission, zoonoses, and reverse zoonoses