Publications by authors named "Todd R Callaway"

89 Publications

Probiotics and potential applications for alternative poultry production systems.

Poult Sci 2021 Mar 26;100(7):101156. Epub 2021 Mar 26.

Faculty of Bioengineering of Animal Resources, Banat University of Animal Sciences and Veterinary Medicine - King Michael I of Romania, Timisoara, Romania. Electronic address:

Concerns over animal welfare continue to be a critical component of law and policies associated with commercial food animal production. Social and market pressures are the driving forces behind the legislation and result in the change of poultry production management systems. As a result, the movement toward cage-free and aviary-based egg production systems has become standard practices. Cage-based systems being replaced by alternative methods that offer a suitable housing environment to meet or exceed poultry welfare needs and require different management, including the ban of antibiotics in poultry diets. For broiler production, pasture- raised and free-range management systems have become more popular. However, challenges remain from exposure to disease-causing organisms and foodborne pathogens in these environments. Consequently, probiotics can be supplemented in poultry diets as commercial feed additives. The present review discusses the impacts of these probiotics on the performance of alternative poultry production systems for improving food safety and poultry health by mitigating pathogenic organisms and improving egg and meat quality and production.
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http://dx.doi.org/10.1016/j.psj.2021.101156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8181177PMC
March 2021

An overview of health challenges in alternative poultry production systems.

Poult Sci 2021 Mar 27;100(7):101173. Epub 2021 Mar 27.

Department of Animal and Dairy Science, University of Georgia, Athens, GA. Electronic address:

Due to consumer demand and changing welfare standards on health, ecology, equity, and safety concepts, poultry production has changed markedly over the past 20 y. One of the greatest changes to poultry production standards is now offering poultry limited access to the outdoors in alternative and organic poultry production operations. Although operations allowing access to the outdoors are still only a small portion of commercial poultry production, it may impact the gastrointestinal (GIT) health of the bird in different ways than birds raised under conventional management systems. The present review describes current research results in alternative systems by identifying how different poultry production operations (diet, environmental disruptive factors, diseases) impact the ecology and health of the GIT. Various research efforts will be discussed that illustrate the nutritional value of free-range forages and how forages could be beneficial to animal health and production of both meat and eggs. The review also highlights the need for potential interventions to limit diseases without using antibiotics. These alternatives could enhance both economics and sustainability in organic and free-range poultry production.
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http://dx.doi.org/10.1016/j.psj.2021.101173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170424PMC
March 2021

Alternatives to Antibiotics: A Symposium on the Challenges and Solutions for Animal Health and Production.

Antibiotics (Basel) 2021 Apr 21;10(5). Epub 2021 Apr 21.

Office of National Programs, USDA-Agricultural Research Service, Beltsville, MD 20705, USA.

Antibiotics have improved the length and quality of life of people worldwide and have had an immeasurable influence on agricultural animal health and the efficiency of animal production over the last 60 years. The increased affordability of animal protein for a greater proportion of the global population, in which antibiotic use has played a crucial part, has resulted in a substantial improvement in human quality of life. However, these benefits have come with major unintended consequences, including antibiotic resistance. Despite the inherent benefits of restricting antibiotic use in animal production, antibiotics remain essential to ensuring animal health, necessitating the development of novel approaches to replace the prophylactic and growth-promoting benefits of antibiotics. The third International Symposium on "Alternatives to Antibiotics: Challenges and Solutions in Animal Health and Production" in Bangkok, Thailand was organized by the USDA Agricultural Research Service, Faculty of Veterinary Science, Chulalongkorn University and Department of Livestock Development-Thailand Ministry of Agriculture and Cooperative; supported by OIE World Organization for Animal Health; and attended by more than 500 scientists from academia, industry, and government from 32 nations across 6 continents. The focus of the symposium was on ensuring human and animal health, food safety, and improving food animal production efficiency as well as quality. Attendees explored six subject areas in detail through scientific presentations and panel discussions with experts, and the major conclusions were as follows: (1) defining the mechanisms of action of antibiotic alternatives is paramount to enable their effective use, whether they are used for prevention, treatment, or to enhance health and production; (2) there is a need to integrate nutrition, health, and disease research, and host genetics needs to be considered in this regard; (3) a combination of alternatives to antibiotics may need to be considered to achieve optimum health and disease management in different animal production systems; (4) hypothesis-driven field trials with proper controls are needed to validate the safety, efficacy, and return of investment (ROI) of antibiotic alternatives.
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http://dx.doi.org/10.3390/antibiotics10050471DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8142984PMC
April 2021

The Effects of Feeding Antibiotic on the Intestinal Microbiota of Weanling Pigs.

Front Vet Sci 2021 12;8:601394. Epub 2021 Mar 12.

Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States.

This study investigated the use of carbadox in the diet of nursery pigs. Ten pens of weanling piglets were assigned to 2 treatments: one containing carbadox and another without it. From days 21 to 35 of age, the first group of piglets was fed carbadox at 55 mg/kg of diet; followed by 27.5 mg/kg from days 36 to 49; and 0 mg/kg from days 50 to 63. The second group of pigs was fed a control diet without carbadox from days 21 to 63 of age. On days 35, 49, and 63, fecal samples were collected directly from the rectum of 2 piglets in each pen, and the samples were subjected to microbial DNA sequencing and metagenomic functional analysis using the 16S rRNA gene. Feed conversion from days 21 to 63 was improved ( = 0.04) in the group of piglets fed carbadox. Faith's phylogenetic diversity was similar ( = 0.89) for both groups of piglets on day 35, but it was diminished ( = 0.01) in the carbadox-fed group on day 49; however, following the complete removal of carbadox from their diets, this microbial diversity index was once again found to be similar ( = 0.27) in both groups on day 63. Likewise, abundances of , and were all similar between the two groups ( ≥ 0.40) on day 35, but were smaller in the carbadox group ( ≤ 0.05) on day 49; however, on day 63, abundances of all these genera were once again similar ( ≥ 0.29). Metabolic pathways involved in cellular growth, death, and genetic information processing (translation) were found to be similarly expressed in the microbiota of piglets from both groups on day 35 ( ≥ 0.52), but decreased in the carbadox group on day 49 ( ≤ 0.05), and were similar again in both groups on day 63 ( ≥ 0.51). These results revealed that feeding carbadox to piglets during the first 4 weeks after weaning significantly affected their fecal microbiotas; however, 2 weeks after the removal of carbadox, those changes tended to disappear, indicating that the shifts were carbadox-dependent.
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http://dx.doi.org/10.3389/fvets.2021.601394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996051PMC
March 2021

Dynamic Changes in the Gut Microbiome at the Acute Stage of Ischemic Stroke in a Pig Model.

Front Neurosci 2020 3;14:587986. Epub 2020 Dec 3.

Department of Foods and Nutrition, College of Family and Consumer Sciences, University of Georgia, Athens, GA, United States.

Stroke is a major cause of death and long-term disability affecting seven million adults in the United States each year. Recently, it has been demonstrated that neurological diseases, associated pathology, and susceptibility changes correlated with changes in the gut microbiota. However, changes in the microbial community in stroke has not been well characterized. The acute stage of stroke is a critical period for assessing injury severity, therapeutic intervention, and clinical prognosis. We investigated the changes in the gut microbiota composition and diversity using a middle cerebral artery (MCA) occlusion ischemic stroke pig model. Ischemic stroke was induced by cauterization of the MCA in pigs. Blood samples were collected prestroke and 4 h, 12 h, 1 day, and 5 days poststroke to evaluate circulating proinflammatory cytokines. Fecal samples were collected prestroke and 1, 3, and 5 days poststroke to assess gut microbiome changes. Results showed elevated systemic inflammation with increased plasma levels of tumor necrosis factor alpha at 4 h and interleukin-6 at 12 h poststroke, relative to prestroke. Microbial diversity and evenness were reduced at 1 day poststroke compared to prestroke. Microbial diversity at 3 days poststroke was negatively correlated with lesion volume. Moreover, beta-diversity analysis revealed trending overall differences over time, with the most significant changes in microbial patterns observed between prestroke and 3 days poststroke. Abundance of the Proteobacteria was significantly increased, while Firmicutes decreased at 3 days poststroke, compared to prestroke populations. Abundance of the lactic acid bacteria was reduced at 3 days poststroke. By day 5, the microbial pattern returned to similar values as prestroke, suggesting the plasticity of gut microbiome in an acute period of stroke in a pig model. These findings provide a basis for characterizing gut microbial changes during the acute stage of stroke, which can be used to assess stroke pathology and the potential development of therapeutic targets.
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http://dx.doi.org/10.3389/fnins.2020.587986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7744295PMC
December 2020

The relationship between the rumen microbiome and carcass merit in Angus steers.

J Anim Sci 2020 Sep;98(9)

Department of Animal and Dairy Science, University of Georgia, Athens, GA.

The objective of this study was to explore the relationships between ruminal microbial populations from Angus steers that were divergent in carcass traits related to adipose accumulation. Twenty-four feedlot-finished Angus steers (age: 538 ± 21 d; body weight following lairage: 593.9 ± 43.7 kg) were slaughtered, and ruminal contents and carcass data were collected. Ruminal microbial deoxyribonucleic acid (DNA) extraction and 16S ribosomal ribonucleic acid (rRNA) gene sequencing were performed to determine microbial relative abundances, to estimate microbial diversity, and to predict microbial metabolic pathways. A variety of correlation analyses and one-way ANOVA were performed to investigate the relationships between the rumen microbiome and carcass traits. Marbling score (P = 0.001) and longissimus lipid content (P = 0.009) were positively correlated to Chao1 Richness Index, suggesting that increased intramuscular fat was associated with increased numbers of ruminal microbial species. The phyla Tenericutes and TM7 were negatively correlated (P ≤ 0.05) to marbling score and longissimus lipid content, indicating that lower abundances of these phyla may be associated with improvements in intramuscular fat content. Greater abundance of the bacterial family S24-7 was positively correlated (P = 0.002) to marbling score. Analysis by marbling classification revealed further linkages to microbial richness (P ≤ 0.063), diversity (P = 0.044), and S24-7 (P < 0.001) populations. Computational prediction of the microbial metabolic pathways revealed no differences (P ≥ 0.05) in metabolic pathway expression in rumen microbes between steers in the high- and low-marbling classes. Several phyla, families, and genera were positively correlated (P ≤ 0.05) to both rib fat thickness and yield grade. Collectively, our results suggest that microbial composition is associated to differing performance in carcass adipose traits. Overall, most of the bacterial taxa correlated to the intramuscular and subcutaneous fat depots did not overlap, suggesting the microbial population end products likely impacted adipose accumulation largely via separate adipogenic pathways of the host animal.
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http://dx.doi.org/10.1093/jas/skaa287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7526868PMC
September 2020

The impact of feed efficiency selection on the ruminal, cecal, and fecal microbiomes of Angus steers from a commercial feedlot.

J Anim Sci 2020 Jul;98(7)

Department of Animal and Dairy Science, University of Georgia, Athens, GA.

Feed is the greatest cost of animal production, so reducing it is critical to increase producer profits. In ruminants, the microbial population within the gastrointestinal tract (GIT) is critical to nutrient digestion and absorption in both the rumen and the hindgut. The objective of this study was to determine the bacterial taxonomic profile of the rumen, cecum, and feces of feedlot steers at slaughter in order to link feed efficiency and the GIT bacterial populations from these three locations. Twenty commercial Angus steers were selected and divided into two groups according to their residual feed intake (RFI) classification determined during the feedlot-finishing period: high-RFI (n = 10) and low-RFI (n = 10). After the ruminal, cecal, and fecal samples were collected at slaughter, DNA extraction and 16S rRNA gene sequencing were performed on them to determine their bacterial composition. One-way ANOVA was performed on the animal performance data, alpha diversities, and bacterial abundances using RFI classification as the fixed effect. Overall, the ruminal bacterial population was the most different in terms of taxonomic profile compared with the cecal and fecal populations as revealed by beta diversity analysis (P < 0.001). Moreover, bacterial richness (Chao1) was greatest (P = 0.01) in the rumen of the high-RFI group compared with the low-RFI group. In contrast, bacterial richness and diversity in the intestinal environment showed that Chao1 was greater (P = 0.01) in the cecum, and the Shannon diversity index was greater in both the cecum and feces of low-RFI compared with high-RFI steers (P = 0.01 and P < 0.001, respectively). Ruminococcaceae was more abundant in the low-RFI group in the cecum and feces (P = 0.01); fecal Bifidobacteriaceae was more abundant in high-RFI steers (P = 0.03). No correlations (P ≥ 0.13) between any ruminal bacterial family and RFI were detected; however, Ruminococcaceae, Mogibacteriaceae, Christensenellaceae, and BS11 were negatively correlated with RFI (P < 0.05) in the cecum and feces. Succinivibrionaceae in the cecum was positively correlated with RFI (P = 0.05), and fecal Bifidobacteriaceae was positively correlated with RFI (P = 0.03). Results collectively indicate that in addition to the ruminal bacteria, the lower gut bacterial population has a significant impact on feed efficiency and nutrient utilization in feedlot steers; therefore, the intestinal bacteria should also be considered when examining the basis of ruminant feed efficiency.
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http://dx.doi.org/10.1093/jas/skaa230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7392532PMC
July 2020

A microencapsulated feed additive containing organic acids, thymol, and vanillin increases in vitro functional activity of peripheral blood leukocytes from broiler chicks.

Poult Sci 2020 Jul 15;99(7):3428-3436. Epub 2020 Apr 15.

Vetagro S.p.A., 42124, Reggio Emilia, Italy; DIMEVET, University of Bologna, Ozzano Emilia, Italy.

During the first week after hatch, young chicks are vulnerable to pathogens as the immune system is not fully developed. The objectives of this study were to determine if supplementing the starter diet with a microencapsulated feed additive containing citric and sorbic acids, thymol, and vanillin affects in vitro functional activity of peripheral blood leukocytes (PBLs). Day-old chicks (n = 800) were assigned to either a control diet (0 g/metric ton [MT]) or a diet supplemented with 500 g/MT of the microencapsulated additive. At 4 D of age, peripheral blood was collected (100 birds per treatment), and heterophils and monocytes isolated (n = 4). Heterophils were assayed for the ability to undergo degranulation and production of an oxidative burst response while nitric oxide production was measured in monocytes. Select cytokine and chemokine mRNA expression levels were also determined. Statistical analysis was performed using Student t test comparing the supplemented diet to the control (P ≤ 0.05). Heterophils isolated from chicks fed the microencapsulated citric and sorbic acids, thymol, and vanillin had higher (P ≤ 0.05) levels of degranulation and oxidative burst responses than those isolated from chicks on the control diet. Heterophils from the supplemented chicks also had greater (P ≤ 0.05) expression of IL10, IL1β, and CXCL8 mRNA than those from control-fed chicks. Similarly, nitric oxide production was significantly (P ≤ 0.05) higher in monocytes isolated from birds fed the supplement. The cytokine and chemokine profile in monocytes from the supplement-fed chicks showed a significant (P ≤ 0.05) drop in IL10 mRNA expression while IL1β, IL4, and CXCL8 were unchanged. In conclusion, 4 D of supplementation with a microencapsulated blend made up of citric and sorbic acids, thymol, and vanillin enhanced the in vitro PBL functions of degranulation, oxidative burst, and nitric oxide production compared with the control diet. Collectively, the data suggest feeding broiler chicks a diet supplemented with a microencapsulated blend of citric and sorbic acids, thymol, and vanillin may prime key immune cells making them more functionally efficient and acts as an immune-modulator to boost the inefficient and undeveloped immune system of young chicks.
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http://dx.doi.org/10.1016/j.psj.2020.03.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7597814PMC
July 2020

The cecal and fecal microbiomes and metabolomes of horses before and after metronidazole administration.

PLoS One 2020 22;15(5):e0232905. Epub 2020 May 22.

Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.

Antibiotic administration can be a cause of gastrointestinal disease in horses, creating a disruption in the normal population and function of bacteria found in the hindgut. The objective of this study was to describe the changes in the cecal and fecal microbiomes and metabolomes of clinically healthy horses before and after metronidazole administration. Metronidazole (15 mg/kg BID PO) was given to five horses with cecal cannulas. The study was suspended on Day 3 due to adverse gastrointestinal effects. Cecal and fecal samples were obtained before (Days minus52, m28, m14, and 0) and after (Days 7, 14, 28, and 52) metronidazole administration. DNA was extracted from the cecal and fecal samples, and 16S rRNA genes were sequenced. Richness and evenness indices were significantly decreased by metronidazole administration in both cecal and fecal samples, but the overall composition was only significantly changed in fecal samples on Day 3 (ANOSIM, p = 0.008). The most dominant phyla were Bacteroidetes and Firmicutes in all groups examined. In fecal samples, significant changes of the phyla Actinobacteria, Spirochaetes, Lentisphaerae, and Verrucomicrobia occurred on Day 3, which correlated with clinical signs of gastrointestinal disease. The metabolome was characterized by mass spectrometry-based methods and only named metabolites were included in the analysis. Fecal, but not cecal, metabolites were significantly affected by metronidazole. The fecal metabolites affected represent diverse metabolic pathways, such as the metabolism of amino acids, carbohydrates, lipids, nucleic acids and cofactors and vitamins. Metronidazole administration has potential to cause adverse effects in horses, alters the bacterial composition of the horse's cecal and fecal content, and the metabolome of fecal samples.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232905PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7244109PMC
August 2020

Translocation of Orally Inoculated Following Mild Immunosuppression in Holstein Calves and the Presence of the in Ground Beef Samples.

Foodborne Pathog Dis 2020 09 5;17(9):533-540. Epub 2020 May 5.

College of Agricultural Sciences and Natural Resources, Texas Tech University, Lubbock, Texas, USA.

The objective of this study was to determine if immunosuppression through daily dexamethasone (DEX) infusion altered translocation from the gastrointestinal tract. Weaned Holstein steers ( = 20; body weight [BW] = 102 ± 2.7 kg) received DEX ( = 10; 0.5 mg/kg BW) or saline (control [CON];  = 10;) for 4 days (from day -1 to 2) before oral inoculation of naldixic acid-resistant Typhimurium (SAL; 3.4 × 10 colony-forming units [CFU]/animal) on day 0. Fecal swabs were obtained daily, and blood was collected daily for hematology. At harvest (day 5), ileum, cecal fluid, lymph nodes (ileocecal, mandibular, popliteal, and subscapular), and synovial (stifle, coxofemoral, and shoulder) samples were collected for isolation of the inoculated strain of SAL. White blood cell (WBC) and neutrophil concentrations were elevated ( < 0.01) in DEX calves following each administration event. Following inoculation, 100% of DEX calves shed the experimental strain of SAL for all 5 days, 90% of CON calves shed from day 1 to 3, and 100% of CON calves shed from day 4 to 5. Greater ( < 0.01) concentrations of SAL were quantified from the cecum of DEX calves (3.86 ± 0.37 log CFU/g) compared with CON calves (1.37 ± 0.37 log CFU/g). There was no difference in SAL concentrations between DEX and CON calves in ileal tissue ( = 0.07) or ileocecal ( = 0.57), mandibular ( = 0.12), popliteal ( = 0.99), or subscapular ( = 0.83) lymph nodes. Of the stifle samples collected, 3.3% were positive for SAL, highlighting a contamination opportunity during hindquarter breakdown. While more research is needed to elucidate the interactions of immunosuppression and pathogen migration patterns, these data confirm that orally inoculated SAL can translocate from the gastrointestinal tract and be harbored in atypical locations representing a food safety risk.
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http://dx.doi.org/10.1089/fpd.2019.2761DOI Listing
September 2020

PB6 Supplementation in Weaned Holstein Steers During an Experimental Challenge.

Foodborne Pathog Dis 2020 08 28;17(8):521-528. Epub 2020 Apr 28.

Kemin Industries, Inc., Des Moines, Iowa, USA.

To evaluate the effects of a patented probiotic, weaned Holstein steers, not shedding ( = 40; ∼90 kg), were supplemented (CLO) or not (CON) with CLOSTAT (13 g/hd per day; Kemin Industries, Des Moines, IA) in a starter ration for 35 d. The calves were assigned to one of four treatments in a 2 × 2 factorial design with CLO and CON calves that were orally administered (STM) or not (NoSTM). Calves were challenged with 1.6 × 10 colony-forming unit (CFU) Typhimurium (resistant to 50 μg/mL nalidixic acid) in 1 L of milk replacer on day 0. Blood samples were collected through jugular catheters every 6 h for 96 h, and body temperature was measured every 5 min through indwelling rectal temperature recording devices. Five calves from each treatment were harvested 48 h postchallenge, and the remaining calves were harvested 96 h postchallenge. During necropsy, tissues were collected for the isolation and quantification of the inoculated STM from various tissues. The CLOSTM group had reduced STM concentrations in the jejunum, ileum, and transverse colon 48 h after the challenge ( ≤ 0.03), but were not different 96 h postchallenge ( > 0.05). Decreased ( < 0.01) pyrexia was observed after the challenge in CLOSTM calves when compared with CONSTM calves. White blood cells and lymphocyte counts were increased ( ≤ 0.05) in CLOSTM calves after the challenge in comparison with other treatments. In calves given STM, the CLO group had greater feed intake before and after the challenge ( < 0.01) compared with the CON group. Increased serum IL-6 and IFN-γ concentrations were observed in the CONSTM group compared with other treatments. Overall, CLO reduced presence and concentrations in gastrointestinal tissues while simultaneously reducing the severity of the challenge as indicated by blood parameters and the reduced febrile response.
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http://dx.doi.org/10.1089/fpd.2019.2757DOI Listing
August 2020

Comparison of the ruminal and fecal microbiotas in beef calves supplemented or not with concentrate.

PLoS One 2020 13;15(4):e0231533. Epub 2020 Apr 13.

Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States of America.

Most of the research efforts involving the bovine gastrointestinal microbiota have focused on cattle's forestomach, particularly the rumen, so information concerning the bovine fecal microbiota is more scarce, especially in young beef cattle. The present study was performed to evaluate the ruminal and fecal microbiotas of beef calves as they reached the end of their nursing phase. A total of 18 Angus cow/calf pairs were selected and assigned to one of two treatment groups for the last 92 days of the calves' nursing period, as follows: 1) calves were supplemented with concentrate in a creep feeding system; or 2) control group with no supplementation of calves. After 92 days, ruminal and fecal samples were individually obtained from calves in both groups, and their microbiotas were evaluated using 16S rRNA gene sequencing. Ruminal samples were predominated by Prevotella (18 to 23% of the total bacterial abundance), regardless if calves received supplementation or not; however, in the feces, Prevotella was only the seventh most abundant genus (0.6 to 2.1% of total bacterial abundance). Both the rumen (P = 0.01) and the feces (P = 0.05) of calves that received supplementation had greater abundance of Firmicutes. In addition, calves that were supplemented had lower abundance of Fibrobacteres (P = 0.03) in their rumens. Regardless if the calves were supplemented or not, Faith's Phylogenetic Diversity index (P ≤ 0.007) and total concentration of short chain fatty acids (P < 0.001) were both greater in the rumen than in the feces of calves. In summary, the ruminal and fecal microbiotas of weanling beef calves were considerably distinct. Additionally, supplementation with creep feed caused some significant changes in the composition of the gastrointestinal microbiota of the calves, especially in the rumen, where supplementation caused an increase in Firmicutes and a decrease in abundance of Fibrobacteres.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231533PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7153887PMC
July 2020

Effect of Supplemental Protease on Growth Performance and Excreta Microbiome of Broiler Chicks.

Microorganisms 2020 Mar 27;8(4). Epub 2020 Mar 27.

Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA.

One-day-old chicks were assigned one of four dietary treatments in a 2 × 2 factorial design in which the main effects were diet (adequate vs. low protein) and the addition of protease (0 vs. 200 g/1000 kg of feed). Chick performance (days 0-14) was recorded and their excreta were analyzed for short chain fatty acids, ammonia, and composition of the microbiota using 16S rRNA gene sequencing. Birds fed the low protein diet had lower body weight gain and poorer overall feed conversion ratio (FCR) ( 0.04); however, these parameters were not affected by the inclusion of protease ( 0.27). Protease inclusion did not affect any particular bacterial genus in the excreta, but it increased the total number of observed OTUs ( = 0.04) and Faith's phylogenetic diversity ( = 0.05). Abundance of and were lower in the excreta of chicks fed the low protein diet ( = 0.01). Abundance of was associated with poorer FCR, while was associated with improved FCR ( 0.009). Although diet had a stronger impact than protease on chick performance, both diet and protease yielded some changes in the intestinal microbiotas of the birds.
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http://dx.doi.org/10.3390/microorganisms8040475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232218PMC
March 2020

Comparison of 2 fixatives in the porcine colon for in situ microbiota studies.

J Anim Sci 2019 Dec;97(12):4803-4809

Department of Veterinary Pathobiology, Texas A&M University, College Station, TX.

Fixation is the first step towards preservation of tissues and can impact downstream histological applications. Historically, formalin has been the fixative of choice in both research and clinical settings due to cost, accessibility, and broad applicability. Here, we describe a method for collection of porcine colon, and compare the usage of Carnoy's solution (CS) to a 10% neutral buffered formalin (NBF) in tissue fixation. Consecutive colon samples were collected from 24 four-wk-old piglets and fixed in CS for 45 min or NBF for 24 h. We measured the thickness of the inner mucus layer using Alcian Blue stain and found thicker inner mucus layers in porcine colons fixed with CS as compared to NBF (P < 0.0001). Carnoy's solution-fixed colon exhibited greater bacterial cell counts than NBF-fixed colon (P < 0.0022) after labeling with an eubacterial probe in fluorescent in situ hybridization (FISH). No difference was observed between the mucosal height (P = 0.42) and number of goblet cells (P = 0.66) between the 2 fixatives. From this, we concluded CS is more suitable than NBF for the preservation of the mucus layer and the associated mucosal bacteria in the porcine colon without compromising on overall tissue morphology. This study provides a useful sampling and fixation methodology for histology studies in the porcine gastrointestinal tract, and may be beneficial to microbiota, pathology, and nutrition studies.
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http://dx.doi.org/10.1093/jas/skz325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6915214PMC
December 2019

Changes in the Hematological Variables in Pigs Supplemented With Yeast Cell Wall in Response to a Challenge in Weaned Pigs.

Front Vet Sci 2019 24;6:246. Epub 2019 Jul 24.

USDA, ARS, Food and Feed Safety Research Unit, College Station, TX, United States.

Stressors experienced by pigs at weaning may negatively impact health and productivity. Thus, supplements that enhance pig immunity during the early post-weaned period are of great interest to the swine industry. The objective of this experiment was to evaluate the performance and hematological responses of weaned pigs supplemented with yeast cell wall (YCW) when challenged orally with . Weaned pigs were assigned to one of three treatments for 22d ( = 13/treatment): Control diet, which was a non-medicated starter diet (Control); Control diet supplemented with YCW at 250 mg/kg BW (YCW250; Phileo Lesaffre Animal Care, Milwaukee, Wisconsin, USA); and Control diet supplemented with YCW at 500 mg/kg BW (YCW500). On d19 blood samples were collected from -6 to 72 h relative to oral (1 × 10 cfu/pig) challenge. Gain:feed was greater ( = 0.01) in YCW250 treatment compared to both Control and YCW500 pigs. Baseline intraperitoneal temperature was greater ( < 0.001) in YCW250 pigs than Control or YCW500 pigs. There was a treatment x time interaction for the change in intraperitoneal temperature ( < 0.01), post-challenge cortisol, white blood cell counts (WBC), neutrophils, and neutrophil:lymphocyte ratio ( ≤ 0.03). Control pigs had greater ( < 0.05) cortisol concentrations than both YCW-supplemented groups at 0 h, but Control pigs had reduced ( < 0.05) cortisol compared to YCW500 pigs at 24 and 30 h post-challenge. Control pigs had greater ( < 0.05) WBC counts than both YCW-supplemented groups 6 and 12 h post-challenge, and YCW250 pigs had reduced ( < 0.01) WBC counts than Control and YCW500 pigs 18 h post-challenge. Neutrophil counts were greater ( < 0.05) in Control pigs than both YCW-supplemented groups at 6 and 12 h post-challenge and were greater ( = 0.02) than YCW250 pigs at 18 h post-challenge. Lymphocytes were greater ( < 0.001) in Control and YCW500 pigs pre- and post-challenge compared to YCW250 pigs. Control pigs had the greatest ( < 0.001) monocyte counts compared to YCW treatments. There was no effect of yeast supplementation on fecal shedding or counts in the rectum, colon or cecum ( ≥ 0.05). While some differences were observed in intraperitoneal temperature and some hematological variables, data suggests there were minimal effects of yeast supplementation on the acute immune response to challenge.
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http://dx.doi.org/10.3389/fvets.2019.00246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6667829PMC
July 2019

Analysis of the Rumen Microbiota of Beef Calves Supplemented During the Suckling Phase.

Front Microbiol 2019 28;10:1131. Epub 2019 May 28.

Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States.

A study was conducted to examine the effects of supplementing beef calves during their suckling phase (popularly known as creep feeding) with supplements that contained or did not contain the enzyme xylanase. Forty-two cow-calf pairs were divided into three groups and assigned to one of three treatments for a period of 105 days, as follows: (1) No supplemental feed for calves (control; CON); (2) Corn and soybean meal-based supplement feed for calves (positive control; PCON); and (3) Same feed regimen as PCON with xylanase added to the supplement (enzyme; ENZ). After 105 days, out of the 42 calves participating in the study, 25 male calves were randomly selected (8 from CON, 9 from PCON, and 8 from ENZ) and samples of their forestomach were collected by esophageal tubing. Immediately after this procedure, all calves were weaned, commingled, and placed in a common post-weaning diet for 4 weeks. At the end of this period, ruminal fluid was once again collected from the same 25 calves. All samples were subjected to DNA extraction and 16S rRNA gene sequencing. At weaning, most of the alpha diversity indexes were greater in CON; however, no differences ( ≥ 0.23) in alpha diversity were observed in samples collected 4 weeks after weaning. Regardless of treatment, 2 phyla - and - comprised approximately 80% of the total bacterial abundance of samples collected on both days. At the genus level, an effect of diet ( = 0.02) was observed for in the samples collected at weaning; however, no differences were detected in the samples collected 4 weeks after weaning. Calf average daily gain (ADG) during the 105-day creep feeding trial tended ( = 0.09) to be greater in the groups that received supplementation, with the greatest numerical value observed in ENZ. Moreover, there was a positive correlation (ρ = 0.43; = 0.03) between ADG and abundance of , indicating the importance of this bacterial group for ruminants. In summary, most of the significant differences found in this study were detected at weaning, and the majority of them disappeared 4 weeks after the calves were weaned and commingled.
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http://dx.doi.org/10.3389/fmicb.2019.01131DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6547912PMC
May 2019

Paenibacillus 79R4, a potential rumen probiotic to enhance nitrite detoxification and methane mitigation in nitrate-treated ruminants.

Sci Total Environ 2019 Jun 25;671:324-328. Epub 2019 Mar 25.

United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845, USA.

The effects of supplemental nitrate administered alone or with a denitrifying ruminal bacterium, designated Paenibacillus 79R4 (79R4) intentionally selected for enhanced nitrate- and nitrite-metabolizing ability, on select rumen fermentation characteristics was examined in vivo. Rumen and blood samples were collected from cannulated Holstein steers one day prior to and one day after initiation of treatments applied as three consecutive intra-ruminal administrations of nitrate, to achieve the equivalent of 83 mg sodium nitrate/kg body weight day, given alone or with the nitrite-selected 79R4 (provided to achieve 10 cells/mL rumen fluid). Results revealed a day effect on methane-producing activity, with rates of methane production by ruminal microbes being more rapid when collected one day before than one day after initiation of treatments. Nitrate-metabolizing activity of the rumen microbes was unaffected by day, treatment or their interaction. A day by treatment interaction was observed on nitrite-metabolizing activity, with rates of nitrite metabolism by rumen microbes being most rapid in populations collected one day after initiation of treatment from steers treated with nitrate plus 79R4. A day by treatment interaction was also observed on plasma methemoglobin concentrations, with concentrations being lower from steers one day after initiation of treatments than from collected one day prior to treatment initiation and concentrations being lowest in steers treated with nitrate plus 79R4. A major effect of treatment was observed on accumulations of most prominent and branched chain volatile fatty acids produced and amounts of hexose fermented in the rumen of animals administered nitrate, with concentrations being decreased in steers administered nitrate alone when compared to steers treated with nitrate plus the 79R4. These results demonstrate that the nitrite-selected Paenibacillus 79R4 may help prevent nitrite toxicity in nitrate-treated ruminants while maintaining benefits of reduced methane emissions and preventing inhibition of fermentation efficiency by the microbial ecosystem.
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http://dx.doi.org/10.1016/j.scitotenv.2019.03.390DOI Listing
June 2019

Modulation of the Immune Response to Improve Health and Reduce Foodborne Pathogens in Poultry.

Microorganisms 2019 Feb 28;7(3). Epub 2019 Feb 28.

Vetagro S.p.A., Via Porro 2, 42124, Reggio Emilia, Italy.

and are the two leading causes of bacterial-induced foodborne illness in the US. Food production animals including cattle, swine, and chickens are transmission sources for both pathogens. The number of outbreaks attributed to poultry has decreased. However, the same cannot be said for where 50⁻70% of human cases result from poultry products. The poultry industry selects heavily on performance traits which adversely affects immune competence. Despite increasing demand for poultry, regulations and public outcry resulted in the ban of antibiotic growth promoters, pressuring the industry to find alternatives to manage flock health. One approach is to incorporate a program that naturally enhances/modulates the bird's immune response. Immunomodulation of the immune system can be achieved using a targeted dietary supplementation and/or feed additive to alter immune function. Science-based modulation of the immune system targets ways to reduce inflammation, boost a weakened response, manage gut health, and provide an alternative approach to prevent disease and control foodborne pathogens when conventional methods are not efficacious or not available. The role of immunomodulation is just one aspect of an integrated, coordinated approach to produce healthy birds that are also safe and wholesome products for consumers.
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http://dx.doi.org/10.3390/microorganisms7030065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6462950PMC
February 2019

Evaluation of active dried yeast in the diets of feedlot steers. II. Effects on rumen pH and liver health of feedlot steers1.

J Anim Sci 2019 Mar;97(3):1347-1363

Department of Animal Science, Texas A&M University, College Station, TX.

The objective of this trial was to determine the benefits of supplementing active dried yeast (ADY; 3 × 1010 CFU/d of Saccharomyces cerevisiae) in diets of growing and finishing steers on ruminal pH and liver health, and evaluate the relationship of these variables with performance traits. Growing beef steers (n = 120) were blocked by weight (i.e., heavy and light) and allocated to 1 of 4 pens in an automated feed intake monitoring system. Steers were fed either control (CON; no ADY) or ADY supplemented in 4 sequential diets: grower diet from days 0 to 70, 2 step up diets (STEP1 and STEP2) for 7 d each, and finishing diet from days 85 to 164. Indwelling rumen boli were administered to monitor rumen pH during days 56 to 106 during the dietary transition. An exchange of pen assignment, within block, occurred on day 70 resulting in 4 final treatment (TRT) assignments: steers fed CON before and after the exchange (CC; n = 30), steers fed CON before and ADY after the exchange (CY; n = 30), steers fed ADY before and CON after the exchange (YC; n = 30), and steers fed ADY (YY; n = 30). Ruminal parameters were analyzed as a randomized complete block design with repeated measures of day, diet and TRT as fixed effects, and block as random effects, using 2 approaches: preliminary analysis of the means or drift analysis (DA; units change from basal values over time). Ruminal pH duration (DUR) below 6.0 (P = 0.05) and 5.8 (P = 0.05) was greater for CY steers than CC steers. Acidosis bout prevalence (pH < 5.6 for 180 consecutive minutes; P < 0.01) and bout DUR (P = 0.05) were greater for CY than other TRT groups. The DA indicated that the ruminal pH variables range, variance, and amplitude of steers in the YC group drifted further from basal pH values than CY and YY steers during the dietary transition (P ≤ 0.02), indicating that removing ADY during the dietary transition was not favorable, but including ADY may reduce ruminal fluctuation. Steers with fewer days experiencing bouts (DEB) had numerically greater ADG (P = 0.11) and tended to have greater G:F (P = 0.06). Liver abscess severity negatively affected ADG (P = 0.04). However, liver abscess severity was not affected by DEB (P = 0.90). There is evidence to suggest that the addition of the specific ADY strain in the diets of beef cattle during the dietary transition may aid in ruminal stabilization, but our study did not find evidence that acidosis bouts were related to abscess prevalence or severity.
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http://dx.doi.org/10.1093/jas/skz008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396254PMC
March 2019

Evaluation of active dried yeast in the diets of feedlot steers-I: Effects on feeding performance traits, the composition of growth, and carcass characteristics1.

J Anim Sci 2019 Mar;97(3):1335-1346

Department of Animal Science, Texas A&M University, College Station, TX.

The use of active dried yeast (ADY) in the diets of feedlot steers may improve feed efficiency, growth performance, and reduce days on feed. Strategic timing of ADY inclusion in the diet may increase feed conversion or aid in the dietary transition from growing to finishing diets. One hundred twenty steers, blocked by weight, were fed four diets for 164 d: grower (70 d), first transition diet (7 d), second transition diet for (7 d), and finisher (80 d) in a GrowSafe System. Four treatment sequences of ADY inclusion were evaluated in a Balaam's design where steers were fed a control diet before and after the grower phase (CC), control before and ADY after the grower phase (CY), ADY before and control after the grower phase (YC), and ADY before and after the grower phase (YY). A random coefficients model was used to evaluate the following variables of interest: feeding performance and growth traits, including biometric measurements and carcass ultrasound measurements, and carcass characteristics. Treatment was a fixed effect and block was a random effect. Treatment did not affect feeding performance or behavior (P ≥ 0.14). The rate of change of biometric measurements were not different (P ≥ 0.16) across treatment groups except for rib girth circumference, which was greater for the YY and CY groups intermediate for the CC group and least for the YC group (0.828 and 0.809 vs. 0.751 vs. 0.666 cm/d, respectively; P < 0.01). Faster growth rates of rib girth circumference resulted in larger final measurements for steers that were finished on ADY (P < 0.01). Ultrasound measurements (backfat, LM area, intra-muscular fat, and rump fat) were not different across treatments (P ≥ 0.15). However, there was a tendency for the YC group to have a slower rate of back fat deposition than other treatment groups (P = 0.09). Steers' final shrunk BWs did not differ (P = 0.61), but shrink percentage was greater for CC than for YY groups (3.7% vs. 2.7%, respectively; P = 0.05). Carcass characteristics were not different across treatments (P ≥ 0.20). Crude fat, CP, ash and moisture analyses of the 9th to 11th rib section were not different across treatments, and there was no difference in adjusted final shrunk BW (P ≥ 0.45). Feeding the ADY strain used in this study to growing and finishing feedlot steers increased rib girth circumference development rate and reduced shrink loss without affecting feeding behavior, feeding performance, or carcass characteristics.
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http://dx.doi.org/10.1093/jas/skz007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396235PMC
March 2019

Effect of waste milk pasteurization on fecal shedding of Salmonella in preweaned calves.

J Dairy Sci 2018 Oct 1;101(10):9266-9274. Epub 2018 Aug 1.

Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, USDA-Agricultural Research Service, College Station, TX 77845.

The objective of the current research was to determine if pasteurization of nonsaleable waste milk influences fecal Salmonella concentrations and prevalence, or antimicrobial susceptibility and serotype of the cultured isolates. Holstein dairy calves (n = 211) were housed on a single commercial dairy in the southwestern United States and randomly allotted to be fed either pasteurized (PWM; n = 128 calves) or nonpasteurized waste milk (NPWM; n = 83 calves). Fecal samples were collected via rectal palpation or from freshly voided, undisturbed fecal pats, weekly during the first 4 wk of the animal's life and then again at weaning. Eight total collections were made and 1,117 fecal samples cultured for Salmonella. One isolate from each culture-positive fecal sample was preserved for antimicrobial susceptibility screening and serotyping. Sixty-nine percent of the fecal samples were culture positive for Salmonella with no difference due to treatment (67.7 and 69% Salmonella positive for PWM and NPWM treatments, respectively). Few fecal samples (178/1,117; 15.9%) contained Salmonella concentrations above the limit of detection (∼1 cfu/g of feces) with concentrations ranging from 1.0 to 6.46 cfu (log)/g of feces. Concentration was not affected by treatment. Seventeen different serotypes were identified, the majority of which were Montevideo and Anatum. A greater percentage of Typhimurium (87 vs. 13%), Muenchen (88 vs. 12%), and Derby (91 vs. 9%) were recovered from calves fed PWM compared with NPWM-fed calves. Conversely, Newport (12.5 vs. 86%), Bredeney (22.2 vs. 77.8%), and Muenster (12.5 vs. 87.5%) were lower in PWM compared with NPWM treatments. The majority (66.7%) of isolates were susceptible to all of the antibiotics examined. Results from this one commercial dairy suggest that milkborne Salmonella is not an important vector of transmission in dairy neonates, nor does pasteurization of waste milk influence fecal shedding of this pathogen. Caution should be used, however, when extrapolating results to other farms as Salmonella contamination of milk on farm is well documented. The potential benefits of pasteurization in disease prevention outweigh the potential risks of feeding a nonpasteurized product and warrants incorporation into any calf-rearing program using nonsaleable waste milk for feeding young dairy neonates.
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http://dx.doi.org/10.3168/jds.2018-14668DOI Listing
October 2018

Isolation, characterization and strain selection of a Paenibacillus species for use as a probiotic to aid in ruminal methane mitigation, nitrate/nitrite detoxification and food safety.

Bioresour Technol 2018 Sep 30;263:358-364. Epub 2018 Apr 30.

United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX, USA.

The effects of dietary nitrate and Paenibacillus 79R4 (79R4), a denitrifying bacterium, when co-administered as a probiotic, on methane emissions, nitrate and nitrite-metabolizing capacity and fermentation characteristics were studied in vitro. Mixed populations of rumen microbes inoculated with 79R4 metabolized all levels of nitrite studied after 24 h in vitro incubation. Results from in vitro simulations resulted in up to 2 log colony forming unit reductions in E. coli O157:H7 and Campylobacter jejuni when these were co-cultured with 79R4. Nitrogen gas was the predominant final product of nitrite reduction by 79R4. When tested with nitrate-treated incubations of rumen microbes, 79R4 inoculation (provided to achieve 10 cells/mL rumen fluid volume) complemented the ruminal methane-decreasing potential of nitrate (P < 0.05) while concurrently increasing fermentation efficiency and enhancing ruminal nitrate and nitrite-metabolizing activity (P < 0.05) compared to untreated and nitrate only-treated incubations.
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http://dx.doi.org/10.1016/j.biortech.2018.04.116DOI Listing
September 2018

Effect of sole or combined administration of nitrate and 3-nitro-1-propionic acid on fermentation and Salmonella survivability in alfalfa-fed rumen cultures in vitro.

Bioresour Technol 2017 Apr 12;229:69-77. Epub 2017 Jan 12.

USDA/ARS, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX 77845, USA.

Ruminal methanogenesis is a digestive inefficiency resulting in the loss of dietary energy consumed by the host and contributing to environmental methane emission. Nitrate is being investigated as a feed supplement to reduce rumen methane emissions but safety and efficacy concerns persist. To assess potential synergies of co-administering sub-toxic amounts of nitrate and 3-nitro-1-propionate (NPA) on fermentation and Salmonella survivability with an alfalfa-based diet, ruminal microbes were cultured with additions of 8 or 16mM nitrate, 4 or 12mM NPA or their combinations. All treatments decreased methanogenesis compared to untreated controls but volatile fatty acid production and fermentation of hexose were also decreased. Nitrate was converted to nitrite, which accumulated to levels inhibitory to digestion. Salmonella populations were enriched in nitrate only-treated cultures but not in cultures co- or solely treated with NPA. These results reveal a need for dose optimization to safely reduce methane production with forage-based diets.
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http://dx.doi.org/10.1016/j.biortech.2017.01.012DOI Listing
April 2017

Ruminal Fermentation of Anti-Methanogenic Nitrate- and Nitro-Containing Forages In Vitro.

Front Vet Sci 2016 11;3:62. Epub 2016 Aug 11.

Food and Feed Safety Research Unit, United States Department of Agriculture Agricultural Research Service , College Station, TX , USA.

Nitrate, 3-nitro-1-propionic acid (NPA) and 3-nitro-1-propanol (NPOH) can accumulate in forages and be poisonous to animals if consumed in high enough amounts. These chemicals are also recognized as potent anti-methanogenic compounds, but plants naturally containing these chemicals have been studied little in this regard. Presently, we found that nitrate-, NPA-, or NPOH-containing forages effectively decreased methane production, by 35-87%, during in vitro fermentation by mixed cultures of ruminal microbes compared to fermentation by cultures incubated similarly with alfalfa. Methane production was further decreased during the incubation of mixed cultures also inoculated with Denitrobacterium detoxificans, a ruminal bacterium known to metabolize nitrate, NPA, and NPOH. Inhibition of methanogens within the mixed cultures was greatest with the NPA- and NPOH-containing forages. Hydrogen accumulated in all the mixed cultures incubated with forages containing nitrate, NPA or NPOH and was dramatically higher, exceeding 40 μmol hydrogen/mL, in mixed cultures incubated with NPA-containing forage but not inoculated with D. detoxificans. This possibly reflects the inhibition of hydrogenase-catalyzed uptake of hydrogen produced via conversion of 50 μmol added formate per milliliter to hydrogen. Accumulations of volatile fatty acids revealed compensatory changes in fermentation in mixed cultures incubated with the nitrate-, NPA-, and NPOH-containing forages as evidenced by lower accumulations of acetate, and in some cases, higher accumulations of butyrate and lower accumulations of ammonia, iso-buytrate, and iso-valerate compared to cultures incubated with alfalfa. Results reveal that nitrate, NPA, and NPOH that accumulate naturally in forages can be made available within ruminal incubations to inhibit methanogenesis. Further research is warranted to determine if diets can be formulated with nitrate-, NPA-, and NPOH-containing forages to achieve efficacious mitigation in ruminant methane emissions without adversely affecting fermentative efficiency or risking toxicity to animals.
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http://dx.doi.org/10.3389/fvets.2016.00062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4980585PMC
August 2016

Disinfectant and Antimicrobial Susceptibility Profiles of the Big Six Non-O157 Shiga Toxin-Producing Escherichia coli Strains from Food Animals and Humans.

J Food Prot 2016 08;79(8):1355-70

U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA.

The disinfectant and antimicrobial susceptibility profiles of 138 non-O157 Shiga toxin-producing Escherichia coli strains (STECs) from food animals and humans were determined. Antimicrobial resistance (AMR) was moderate (39.1% of strains) in response to 15 antimicrobial agents. Animal strains had a lower AMR prevalence (35.6%) than did human strains (43.9%) but a higher prevalence of the resistance profile GEN-KAN-TET. A decreasing prevalence of AMR was found among animal strains from serogroups O45 > O145 > O121 > O111 > O26 > O103 and among human strains from serogroups O145 > O103 > O26 > O111 > O121 > O45. One animal strain from serogroups O121 and O145 and one human strain from serogroup O26 had extensive drug resistance. A high prevalence of AMR in animal O45 and O121 strains and no resistance or a low prevalence of resistance in human strains from these serogroups suggests a source other than food animals for human exposure to these strains. Among the 24 disinfectants evaluated, all strains were susceptible to triclosan. Animal strains had a higher prevalence of resistance to chlorhexidine than did human strains. Both animal and human strains had a similar low prevalence of low-level benzalkonium chloride resistance, and animal and human strains had similar susceptibility profiles for most other disinfectants. Benzyldimethylammonium chlorides and C10AC were the primary active components in disinfectants DC&R and P-128, respectively, against non-O157 STECs. A disinfectant FS512 MIC ≥ 8 μg/ml was more prevalent among animal O121 strains (61.5%) than among human O121 strains (25%), which may also suggest a source of human exposure to STEC O121 other than food animals. Bacterial inhibition was not dependent solely on pH but was correlated with the presence of dissociated organic acid species and some undissociated acids.
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http://dx.doi.org/10.4315/0362-028X.JFP-15-600DOI Listing
August 2016

Smarter arrow now available in the food safety quiver.

Proc Natl Acad Sci U S A 2015 Oct 23;112(40):12230-1. Epub 2015 Sep 23.

Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA 30322.

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http://dx.doi.org/10.1073/pnas.1516670112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4603462PMC
October 2015

Microencapsulated sorbic acid and pure botanicals affect Salmonella Typhimurium shedding in pigs: a close-up look from weaning to slaughter in controlled and field conditions.

Foodborne Pathog Dis 2015 Oct 23;12(10):813-9. Epub 2015 Jul 23.

3 Istituto Zooprofilattico dell'Emilia Romagna e Lombardia , Brescia, Italy .

The aim of this study was to assess the efficacy of a combination of sorbic acid, thymol, and carvacrol in reducing the prevalence and shedding level of Salmonella Typhimurium in pigs either in a controlled challenge environment or in a production setting. In the first study, 24 weaned piglets were separated in 4 isolation units (6 piglets/isolation unit). Each unit received either a basal diet (no treatment) or a microencapsulated mixture of sorbic acid, thymol, and carvacrol at 1, 2, or 5 g/kg of feed. After 21 d, pigs were orally challenged with 6 log10 colony-forming units of Salmonella Typhimurium. Blood samples and feces from rectal ampullae were collected every week. On d56 of the study, pigs were euthanized and necropsied to collect intestinal contents (jejunum through colon) and ileocecal lymph nodes. Samples were analyzed for Salmonella Typhimurium and serological analysis was also conducted. In the second study, an all-in-all-out multisite pig farm that was positive for monophasic Salmonella Typhimurium was followed throughout a production cycle from weaning to slaughter. Pigs received either a basal diet or the basal diet including 5 g/kg of the microencapsulated additive. Environmental, fecal, and blood samples were collected monthly, and cecal contents and ileocecal lymph nodes were collected at slaughter to isolate and enumerate Salmonella. The results indicate that the additive at 5 g/kg tended to reduce Salmonella fecal prevalence in both a controlled challenge (p=0.07) and in production conditions (p=0.03). Nevertheless, the additive did not reduce the number of pigs seropositive for Salmonella, nor it reduced the Salmonella prevalence at slaughter. The data indicate that these additives are not effective alone but must be used in conjunction with appropriate containment measures at lairage in order to prevent reinfection in pigs and to reduce the number of pigs carrying Salmonella entering the food chain.
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http://dx.doi.org/10.1089/fpd.2015.1953DOI Listing
October 2015

Perspectives on super-shedding of Escherichia coli O157:H7 by cattle.

Foodborne Pathog Dis 2015 Feb 16;12(2):89-103. Epub 2014 Dec 16.

1 Agriculture and Agri-Food Canada, Lethbridge Research Centre , Lethbridge, Alberta, Canada .

Escherichia coli O157:H7 is a foodborne pathogen that causes illness in humans worldwide. Cattle are the primary reservoir of this bacterium, with the concentration and frequency of E. coli O157:H7 shedding varying greatly among individuals. The term "super-shedder" has been applied to cattle that shed concentrations of E. coli O157:H7 ≥ 10⁴ colony-forming units/g feces. Super-shedders have been reported to have a substantial impact on the prevalence and transmission of E. coli O157:H7 in the environment. The specific factors responsible for super-shedding are unknown, but are presumably mediated by characteristics of the bacterium, animal host, and environment. Super-shedding is sporadic and inconsistent, suggesting that biofilms of E. coli O157:H7 colonizing the intestinal epithelium in cattle are intermittently released into feces. Phenotypic and genotypic differences have been noted in E. coli O157:H7 recovered from super-shedders as compared to low-shedding cattle, including differences in phage type (PT21/28), carbon utilization, degree of clonal relatedness, tir polymorphisms, and differences in the presence of stx2a and stx2c, as well as antiterminator Q gene alleles. There is also some evidence to support that the native fecal microbiome is distinct between super-shedders and low-shedders and that low-shedders have higher levels of lytic phage within feces. Consequently, conditions within the host may determine whether E. coli O157:H7 can proliferate sufficiently for the host to obtain super-shedding status. Targeting super-shedders for mitigation of E. coli O157:H7 has been proposed as a means of reducing the incidence and spread of this pathogen to the environment. If super-shedders could be easily identified, strategies such as bacteriophage therapy, probiotics, vaccination, or dietary inclusion of plant secondary compounds could be specifically targeted at this subpopulation. Evidence that super-shedder isolates share a commonality with isolates linked to human illness makes it imperative that the etiology of this phenomenon be characterized.
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http://dx.doi.org/10.1089/fpd.2014.1829DOI Listing
February 2015

Organic acid blend with pure botanical product treatment reduces Escherichia coli and Salmonella populations in pure culture and in in vitro mixed ruminal microorganism fermentations.

Foodborne Pathog Dis 2015 Jan 2;12(1):56-61. Epub 2014 Dec 2.

1 DIMEVET, Università di Bologna , Ozzano Emilia, Italy .

Foodborne pathogenic bacteria can live in the intestinal tract of food animals and can be transmitted to humans via food or indirectly through animal or fecal contact. Organic acid blend products have been used as nonantibiotic modifiers of the gastrointestinal fermentation of food animals to improve growth performance efficiency. However, the impact of these organic acid products on the microbial population, including foodborne pathogens, remains unknown. Therefore, this study was designed to examine the effects of a commercial organic acid and botanical blend product (OABP) on populations of the foodborne pathogenic bacteria, Escherichia coli O157:H7 and Salmonella Typhimurium. Pure cultures (2×10(6) colony-forming units [CFU]/mL) of each pathogen were added to tubes that contained water-solubilized OABP added at concentrations of 0, 0.1, 0.5, 1, 2, 5, and 10% (vol/vol; n=3). Water-solubilized OABP reduced (p<0.05) the growth rate and final populations of E. coli O157:H7 and Salmonella Typhimurium in pure culture at concentrations >2%. E. coli O157:H7 and Salmonella Typhimurium were added (2×10(5) and 3×10(6) CFU/mL, respectively) to in vitro mixed ruminal microorganism fermentations that contained water-solubilized OABP at concentrations of 0, 1, 2, 5, and 10% (vol/vol; n=3) that were incubated for 24 h. OABP addition reduced (p<0.05) final populations of E. coli O157:H7 and Salmonella Typhimurium in the ruminal fluid at concentrations ≥5%. The acetate-to-propionate ratios from the in vitro fermentations were reduced (p<0.05) by OABP treatment ≥5%. Treatments to reduce foodborne pathogens must be economically feasible to implement, and results indicate that organic acid products, such as OABP, can enhance animal growth efficiency and can be used to reduce populations of pathogenic bacteria.
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http://dx.doi.org/10.1089/fpd.2014.1826DOI Listing
January 2015

Isolation of Escherichia coli O157:H7 and Salmonella from migratory brown-headed cowbirds (Molothrus ater), common Grackles (Quiscalus quiscula), and cattle egrets (Bubulcus ibis).

Foodborne Pathog Dis 2014 Oct 31;11(10):791-4. Epub 2014 Jul 31.

Food and Feed Safety Research Unit , Agricultural Research Service, U.S. Department of Agriculture, College Station, Texas.

Zoonotic enteric pathogenic bacteria can live in the intestinal tract of birds and can be transmitted to food animals or humans via fecal contact. In the present study, cecal samples were collected from 376 migratory birds from species often associated with cattle during the fall migration in the Central Flyway of the United States. Brown-headed cowbirds (n=309, Molothrus ater), common grackles (n=51, Quiscalus quiscula), and cattle egrets (n=12, Bubulcus ibis) contained foodborne pathogenic bacteria in their ceca. Salmonella enterica was isolated from 14.9% of all samples, and Escherichia coli O157:H7 from 3.7%. Salmonella serotypes isolated included the following: Muenster, Montevideo, and Typhimurium. Our data suggest that migratory birds associated with cattle could be a vector for zoonotic enteric pathogenic bacteria to be disseminated across long distances.
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http://dx.doi.org/10.1089/fpd.2014.1800DOI Listing
October 2014