Elephant grass [Pennisetum purpureum Schumach. syn. Cenchrus purpureus (Schumach.) Morrone], also known as Napier grass and King grass, includes varieties Taiwán, Gigante, Merkerón, Maralfalfa, and others. The grass achieves high biomass production in tropical-subtropical, temperate, and arid areas. The high-water concentration of elephant grass suggests that ensiling could offer an alternative way to preserve the nutritional quality of the grass during storage, however, some considerations should be addressed because of the particularities of the grass. Ensiling elephant grass may produce adequate fermentation but could suffer effluent losses and subsequent losses of nutrients due to leaching. To improve fermentation and nutrient characteristics of elephant grass silages, several studies were conducted with the inclusion of additives. Lactic acid bacteria inocula have reduced pH and increased crude protein content of elephant grass silage, but aerobic stability of silages could be affected by the bacterial inoculation. There is limited information, however, on the potential of different silage inoculants to reduce growth of spoilage microorganisms during the aerobic phase of silage prepared with elephant grass. Exogenous fibrolytic enzymes also may improve elephant grass silage quality by enhancing microbial fiber-degradation with subsequent increase in lactic acid and its associated pH reduction. Another study approach to improve fermentation and nutritional quality of elephant grass silages involved the addition of different feeds at ensiling, including conventional feeds such corn, wheat, rice bran, and molasses or alternative feeds such as different dehydrated by-products obtained from the food industries of juice and jelly. In the manuscript, the presented scientific information shows the great potential of the different manipulations to improve the quality of elephant grass silages and with possible enhance of the economic profit and sustainability of livestock farming in the tropical areas.

ABSTRACT To study the antimicrobial and uric acid-preserving activity of pine bark tannin on poultry litter composting, antibiotic-free wood chip-based poultry litter was distributed (11 g) to 50-mL conical centrifuge tubes and immediately amended with 1.3 mL0.4 M sodium phosphate buffer (control) or with 1.3 mL condensed tannins from pine bark (Pinus palustris; 9 % tannin wt/vol in water). All tubes (n = 3 tubes/treatment) were inoculated with a novobiocin and naladixic acid-resistant Salmo-nella typhimurium (STNN) to achieve 3.0 log10 CFU/g and incubated at 37oC for 3 days to simulate an initial compost period. Wildtype E. coli and the challenge STNN strain as well as concentrations of ammonia, uric acid and urea were measured on days 0 and 3. Pine bark tannin treatment decreased (p<0.01) STNN populations in the litter by 0.6 log units compared to the controls. Wildtype E. coli populations were unaffected by tannin treatment (p>0.05). Ammonia accumulation decreased (p<0.01) 23% in tannin-treated litter compared to the control (2.8 ± 0.1 µmol/g). Conversely, the residual uric acid concentration was 1.6-fold higher (p=0.02) in litter treated with the pine bark tannin than in the control litter. Urea concentrations were unaffected by tannin treatment (p>0.05). Results suggest that pine bark tannin treatment may preserve uric acid and reduce ammonia volatilization in composted litter while aiding Salmonella control.

AIMS:Determine the antimicrobial effects of 5 μmol ml-1 sodium chlorate, 9 μmol ml-1 nitroethane or 2-nitropropanol as well as lauric acid, myristic acid and the glycerol ester of lauric acid Lauricidin® , each at 5 mg ml-1 , against representative methicillin-resistant staphylococci, important mastitis- and opportunistic dermal-pathogens of humans and livestock. METHODS AND RESULTS:Three methicillin-resistant Staphylococcus aureus and two methicillin-resistant coagulase-negative staphylococci were cultured at 39°C in 5 μmol ml-1 nitrate-supplemented half-strength Brain Heart Infusion broth treated without or with the potential inhibitors. Results revealed that 2-nitropropanol was the most potent and persistent of all compounds tested, achieving 58-99% decreases in mean specific growth rates and maximum optical densities when compared with untreated controls. Growth inhibition did not persist by cultures treated solely with chlorate or nitroethane, with adaptation occurring by different mechanisms after 7 h. Adaptation did not occur in cultures co-treated with nitroethane and chlorate. The medium chain fatty acid compounds had modest effects on all the staphylococci tested except the coagulase-negative Staphylococcus epidermidis strain NKR1. CONCLUSIONS:The antimicrobial activity of nitrocompounds, chlorate and medium chain fatty acid compounds against different methicillin-resistant staphylococci varied in potency. SIGNIFICANCE AND IMPACT OF THE STUDY:Results suggest that differential antimicrobial activities exhibited by mechanistically dissimilar inhibitors against methicillin-resistant staphylococci may yield potential opportunities to combine the treatments to overcome their individual limitations and broaden their activity against other mastitis and dermal pathogens.

Aims Investigate the interactions of organic acids (OAs), acetic, butyric, citric, formic, lactic and propionic acid against 50 Gram-positive vancomycin-resistant Enterococcus faecium (VRE) strains to determine whether pH, undissociated or dissociated acid forms correlate with bacterial inhibition. Methods and Results Concentrations of undissociated and dissociated OAs at the molar minimum inhibitory concentrations (MIC(M)s) of the VRE were calculated using the Henderson-Hasselbalch equation. The pH at the MIC(M)s of all VRE strains against acetic, butyric, formic and propionic acids was similar, 4.66 +/- 0.07, but there was a 1.1 pH unit difference for all six OAs. Inhibition of VRE by all six OAs did not appear to be solely dependent on pH or on the undissociated OA species. The inhibition of VRE by all six dissociated acids was within Delta = 3.1 mmol l(-1). Conclusions Vancomycin-resistant Enterococcus faecium inhibition correlated with the dissociated OA species. A small decrease in the concentration of the dissociated OAs from optimum may result in allowing VRE strains to escape disinfection. Significance and Impact of the Study When an OA is used to disinfect VRE strains, the concentration of the dissociated OA should be carefully controlled. A concentration of at least 20 mmol l(-1) dissociated OA should be maintained when disinfecting VRE.

Poultry litter is a potentially valuable crude protein feedstuff for ruminants but must be treated to kill pathogens before feeding. Composting effectively kills pathogens but risks losses of ammonia during uric acid degradation. Presently, 250-g portions of used wood chip litter (WCL, 73% dry matter) were treated with 125 mL 0.4 M phosphate buffer (pH 6.5) containing Chinook or Galena hop extracts to achieve 0.03 g beta-acid/g WCL. Control WCL was treated with buffer alone. The WCL was distributed (11 g) to 50-mL tubes (3 tubes/treatment per sampling day), inoculated with a marked challenge strain of Salmonella Typhimurium (ST) then capped and incubated at successive 3-day increments at 22oC, 37oC and 42oC. Repeated measures analysis of variance of ammonia, urea and uric acid measured in samples collected on days 0, 3, 6 and 9 revealed a main effect of day on uric acid (P < 0.05), which increased from day 0 to 3 (a high of 9.4 µmol/g) and declined thereafter to its low (4.1 µmol/g) on day 9. A day x treatment interaction was observed (P < 0.05) on ammonia accumulations which increased steadily, accumulating more on day 9 with Galena hops-treated WCL than with control- or Chinook hops-treated WCL (7.3, 6.6 and 5.6 µmol/g, respectively). A main effect of treatment but not day or their interaction was observed on urea accumulations, highest for control, lowest for Galena- and intermediate for Chinook hops-treated WCL (1.7, 0.5 and 1.0 µmol/g, respectively). Analysis of bacterial concentrations revealed little effect of treatment on bacterial counts; however, main effects of day on ST and E. coli were observed (P < 0.05) with both being decreased below detection limits (1 log10 CFU/g) by day 9. These results indicate that composting combined with Chinook hops-treatment may help safely preserve crude protein of WCL.

Poultry litter (PL) contains uric acid which makes it a good crude protein supplement for ruminants. However, PL must be treated to kill pathogens before feeding. Composting effectively kills pathogens but risks loss of ammonia due to uric acid degradation. Because tannins possess antimicrobial activity and can inhibit uric acid metabolism, we tested their ability to preserve uric acid and reduce pathogens during PL composting. Used PL (76% DM) was mixed 2:1 with 0.4 M phosphate buffer (pH 6.5) and distributed (11 g) to 50-mL tubes (3/treatment per sample day) amended with 1 mL buffer alone or containing pine bark, quebracho, chestnut or mimosa tannins to achieve 1.5% wt/vol. Tubes were inoculated with a novobiocin- and naladixic acid-resistant Salmonella Typhimurium (STNN), closed with caps and incubated at successive 3 day increments at 22oC, 37oC and 42oC, respectively. Repeated measures analysis of variance of bacterial numbers enumerated in contents collected on days 0, 6 and 9 revealed a main effect of day (P < 0.0001) but not treatment (P > 0.05) on all populations, with initial counts of E. coli and STNN being decreased from 4.3 and 3.6 log10 CFU/g to below detection limits (1 log10 CFU/g) by day 9. A tendency for a day x treatment interaction was observed on STNN populations (P = 0.09), with STNN being decreased 0.4 log10 CFU/g on day 6 in quebracho-treated litter compared to being increased 0.6 log10 CFU/g in control PL. Analysis of ammonia, urea and uric acid concentrations revealed an effect of day (P < 0.05) but not treatment or their interaction, with concentrations increasing 36, 32 and 27% from initial values (2.9, 3.3 and 4.4 µmol/mL, respectively). Results confirm that composting was an effective pathogen control treatment but revealed little additional benefit due to tannin treatment under the conditions studied here.

Poultry litter (PL) is a valuable nitrogen feed source for ruminants whose gut microbes transform the nitrogen in uric acid into microbial protein. Evidence indicates that nitro-treatment may improve the feed value of composted PL by inhibiting degradation of its nonprotein nitrogen (NPN) during composting but it is not known what effect residual nitrocompounds may have on ruminal NPN metabolism. In this study, freshly collected ruminal fluid from a pasture-reared cow was incubated anaerobically (10 mL/tube) at 39oC in closed-culture tubes supplemented with 0.2 g ground alfalfa, 0.15 g of one-year-old PL and with or without 20 mM 3-nitropropionate (NPA) or ethyl nitroacetate (ENA), concentrations previously shown to be inhibitory of uric acid degradation. Analysis of uric acid, urea and ammonia concentrations measured at 0, 6 and 24 h revealed rates of uric acid and urea disappearance in nitro-treated cultures did not differ from controls (0.10, 0.07 and 0.19 µmol urea 0.09, 0.05 and 0.07 µmol uric acid per mL incubation fluid for controls, NPA- and ENA-treated cultures, respectively). Rates of ammonia accumulations in NPA-treated cultures were similar to controls but lower in ENA-treated cultures (0.16, 0.17 and 0.09 µmol/mL, respectively). Effects of nitro-treatment were observed on headspace gas accumulations, although this was not unexpected as the nitrocompounds are known methane-inhibitors. Less gas volume accumulated in NPA- and ENA-treated cultures compared to controls (26, 21 and 18 mL, respectively) and methane production was lower in NPA- and ENA-treated cultures than controls (0.7, 0.5 and 21 µmol/mL, respectively). Hydrogen accumulations were similar between NPA-treated cultures and controls but higher in ENA-treated cultures (0.1, 0.4 and 0.9 µmol/mL, respectively). These results indicate that residual nitrocompounds in nitro-treated PL will have little if any adverse effect on ruminal NPN metabolism and may beneficially contribute to lowering methane emissions.

Poultry litter contains appreciable amounts of uric acid, which makes it a good CP supplement for ruminants whose gut microbes transform the nitrogen in uric acid into high-quality microbial protein. However, poultry litter must be treated to kill bacterial pathogens before feeding. Presently, we examined the antimicrobial activity of certain nitrocompounds when administered to early-stage composted poultry litter. The 1-yr-old wood chip litter used in this study had been exposed to 2 to 3 flocks reared without antibiotics. Treatments (ethyl nitroacetate, 3-nitropropionate, ethyl-2 nitropropionate, or nitroethane) were applied to 200 g litter by spraying with 100 mL of each nitro treatment (80 mM in 0.4 M phosphate buffer, pH 6.4) to achieve 25 µmol/g litter. Control litter was sprayed with buffer alone. After application, the litter was distributed (11 g) to 50-mL tubes (in triplicate) and inoculated with a novobiocin and naladixic acid–resistant Salmonella Typhimurium (STNN) to achieve 3.0 log10 cfu/g. Tubes were closed with caps, sealed with parafilm, and incubated at 37°C for 3 d, after which time the tube contents were diluted and plated on 3 M Escherichia coli/coliform petri film and Brilliant Green Agar supplemented with 25 and 20 µg/mL novobiocin and naladixic acid, respectively, for enumeration of wildtype E. coli and STNN strain. Ammonia, uric acid, and urea were colorimetrically measured. Analysis of variance revealed that all nitrocompound treatments decreased (P < 0.05) STNN 1.4 to 1.9 log units compared with controls (6.0 ± 0.2 log10 cfu/g). Escherichia coli was decreased (P < 0.05) compared with controls (6.5 ± 0.2 log10 cfu/g) by 0.5 log units with ethyl nitroacetate but did not differ otherwise. Accumulations of ammonia were decreased (P < 0.05) 21 to 27% by the ethyl derivatives compared with controls (2.8 ± 0.1 µmol/g). Uric acid concentrations were 3.4- to 4.5-fold higher (P < 0.05) in litter treated with ethyl 2-nitropropinate and nitroethane than in controls (15.5 ± 1.3 µmol/g). Urea (7.9 ± 2.9 µmol/g) was unaffected by nitro treatment. Results suggest that nitro treatment may help preserve uric acid in composted litter while aiding in Salmonella control.

Competitive exclusion cultures (CEC), which use whole bacterial communities derived directly from the gastrointestinal tract, have been effective to control of pathogens in animals, but its application in humans has not been widely studied. In this work, the inhibitory effect of supernatants obtained from a CEC developed from fecal samples of healthy individuals, was quantified over the growth of intestinal pathogens of public health significance. Baranyi Model was adjusted (R-2 >0.947) to growth curves of Shigella sonnei-(SF1), E. coli EPEC-(EC6) y Salmonella Enteritidis-(SE3) treated with supernatants, in order to estimate kinetic parameters. Both, growth rate and pathogen concentrations were significantly reduced by the action of supernatants in 89.89% and 86.80%, respectively, for the most sensitive bacteria (SF1) and 23.21% and 36.86%, for the most resistant (SE3). A growth delay of more than 14 hours was presented by SF1 and EC6 with the treatments. Thermal and enzymatic (proteinase K and trypsin) sensitivity of supernatants indicate that antagonism was mediated by bacteriocin-like substances. The CEC developed, have biotechnological potential for the production of antimicrobial substances of interest in the food and pharmaceutical industries.

Poultry litter is a byproduct produced in large amounts by intensive poultry production systems. While it contains appreciable amounts of nitrogen as uric acid, which makes it an excellent crude protein feed supplement for ruminants, it is usually a carrier of enteropathogenic bacteria of importance to human health. The objectives of this study were to determine the bactericidal effectiveness of several nitrocompounds, assess their potential to produce a feedstuff that is environmentally safe and their potential as a sustainable technology to preserve the nitrogen contained in poultry litter. Twenty grams of 6-mo-old poultry litter (82.5 ± 1.1% dry matter) were distributed in 709-mL plastic containers, mixed with 7.5 mL of deionized water containing no added nitrocompound or 40 mM 2-nitroethanol, 2-nitro-1-propanol (2nitropropanol), nitroethane, 3-nitropropionic acid or ethylnitroacetate. Each container was then inoculated with approximately 2 × 104 CFU of a Salmonella enterica serovar Typhimurium (NVSL 951776), naturally resistant to 25 µg/mL novobiocin and made resistant to 20 µg/mL naladixic acid, and incubated aerobically at 37°C for 24 h. Samples collected at 0, 6, and 24 h were enumerated for Salmonella. Generic E. coli were enumerated on 3M E. coli/coliform petrifilm in samples collected at 0 and 24 h. Samples were also analyzed spectrophotometrically for determination of uric acid. Data were analyzed for main effects of treatment, time of incubation and their potential interaction on temperature and pH as well as on microbiological concentrations by a repeated measures analysis of variance. Main effects of treatment (P < 0.0001; SEM = 0.159), time (P < 0.0001; SEM = 0.170) and their interaction (P = 0.0001; SEM = 0.417) were observed on Salmonella concentrations. Salmonella concentrations in samples treated with 44 mM 2nitroethanol, 2nitropropanol or ethylnitroacetate were decreased by 0.7 to 1.7 log10CFU/mL within the first 6 h of incubation. Main effects of treatment (P = 0.0100; SEM = 0.108), time (P = 0.0020; SEM = 0.065) and their interaction (P = 0.0145; SEM = 0.160) were observed on generic E. coli concentrations. Main effects of treatment were observed on rates of ammonia accumulation and the residual uric acid concentrations. Urea concentrations were below the limit of detection which under conditions of use was 1 µmol/ml. Results indicate that these environmentally sustainable and safe nitrocompounds negatively impacted potential enteropathogens contained in poultry litter. Additionally, litter treated with these compounds maintained appreciable levels of nutritionally available nitrogen in the form of uric acid, enhancing the value of used poultry litter as a ruminant feed supplement.

A 35-day feeding trial was conducted to evaluate growth, bacterial populations of the gastrointestinal tract (GIT) and immune responses of Litopenaeus vannamei fed diets containing the commercial prebiotic Previda((R)). Diets were formulated to contain Previda((R)) at 0, 0.2, 0.5, 1.0 or 1.6gkg(-1) by weight. At the end of the study, differences in weight gain and survival among treatments were not significant (P>0.05), but denaturing gradient gel electrophoresis analysis revealed that the microbial communities in the GIT changed significantly with the inclusion of dietary Previda((R)) at different levels. Previda((R)) was therefore able to selectively modify the microbial communities in the shrimp's GIT. Although individual bacterial species were not identified, enteric populations in shrimp fed the prebiotic at similar levels of inclusion were genetically similar. In addition, shrimp fed Previda((R)) at 1.6gkg(-1) responded significantly (P<0.05) better immunologically with respect to hemocyte phagocytic capacity, haemolymph protein, hyaline cell counts and haemolymph glucose compared with shrimp fed the basal diet. Although shrimp were not exposed to virulent pathogens in this study, the observed upregulation of some of imm-une responses upon prebiotic supplementation indicates that an improved outcome of such challenges may be anticipated in Previda((R))-fed shrimp under commercial conditions.

We set out to investigate whether Salmonella enterica could be recovered from various tissues of viable neonatal calves immediately following parturition. Eleven samples were aseptically collected from each of 20 calves and consisted of both left and right subiliac and prescapular lymph nodes (LN), mesenteric LN, spleen and liver, as well as intestinal tissue (including luminal contents) from the small intestine, caecum, spiral colon and rectum. In addition, a faecal sample was collected from 19 of the dams. Salmonella was recovered from at least one sample from 10 of the 20 neonates. Across all calves, Salmonella was recovered from 12·7% of all samples and from LN in particular, Salmonella was recovered from 10·0%, 5·0%, and 5·0% of subiliac, prescapular, and mesenteric LN, respectively. Within calves, Salmonella was recovered from 0% to 73% of samples and across tissues, estimates of Salmonella prevalence were greatest in the caecum (30%) but was never recovered from the right pre-scapular LN. These data provide evidence of vertical transmission from a dam to her fetus such that viable calves are born already infected and thereby not requiring faecal-oral exposure for transmission. This new knowledge ought to challenge - or at least add to - existing paradigms of Salmonella transmission dynamics within cattle herds.

The impact of maternal flock age and incubation on embryo metabolism was studied to understand late incubation overheating and mortality in Ross 308 embryos. Fresh broiler hatching eggs (n = 45) were obtained from commercial breeder flocks at 3 ages: Young (Y): 25 to 34 wk, Peak (P): 35 to 45 wk, Old (O): 46 to 54 wk of age), stored for 2 to 4 d at 18°C and 73% RH, then incubated for 14 d at 37.5°C and 56% RH. At 15 d of incubation (E15), 12 fertile eggs per flock age were placed individually in metabolic chambers and subjected to one of 4 machine temperatures (MT; 36.0, 36.5, 37.0, or 37.5°C) until E21.5. The O2 consumption, CO2 production and eggshell temperatures (EST) were recorded and embryonic heat production (EHP) calculated and used as an indicator of embryonic metabolism. At E21.5, quality was assessed using chick weight, length, pipping and hatching times. Data were analyzed by the Proc Mixed procedure of SAS at P < 0.05 significance level. Relation­ ships among MT, parent flock age, EHP and EST were determined by regression. There were no differences in daily O2 consumption, CO2 production or EHP between maternal flock ages or MT. Daily EST was not affected by flock age. The EST at 37.5°C was higher than all other MT treatments except at E20 where it was not different from 37.0°C MT. The daily EST at 37.0°C MT was also higher than the daily EST at 36.5°C and 36.0°C, while 36.5°C had higher daily EST compared with 36.0°C MT. The MT showed a strong positive linear relationship with EST (R2 = 0.89) but there was no relationship between EST and EHP. Egg weight and chick weight increased as flock age increased. There was no effect of flock age on chick length or pipping time but hatching time was shorter for 37.0°C MT compared with all other temperatures. In conclusion, MT had a much greater effect on embryo development than maternal flock age in Ross 308 embryos.

Eimeria spp. invade and damage the intestinal cell lining of broilers resulting in cell necrosis and secondary bacterial infections. The current work investigates the effect of anticoccidial agents, salinomycin in combination with Roxarsone and Eimeria-challenge on the composition of broiler cecal microflora. Three hundred and twenty day-old male Cobb broilers were among four treatment groups: NN (no salinomycin and no Eimeria challenge) and NC (no salinomycin plus Eimeria challenge) received basal diet with no salinomycin, while SN (salinomycin and no Eimeria challenge) and SC (salinomycin plus Eimeria challenge) received basal diet with salinomucin. Broilers in groups NC and SC were orally gavaged on d 28 with a mixed Eimeria spp. challenge. Body weight and Eimeria lesion scores were determined at d 35. Cecal bacterial DNA from broilers at day 28 and day 35 were subjected to 454 pyrosequencing of 16S rDNA for sequence identification. Relative percent abundance and richness of the identified taxa were analyzed. Salinomycin had significant influence on the total number of taxa (p = 0.02) and on cecal microbial community structure (p = 0.002). The mixed Eimeria challenge marginally affected the total number of taxa (p = 0.06) and the composition of microbial communities (p = 0.09). Broiler age, body weight and Eimeria lesion score had no significant effect on the cecal microbial communities. Results from this study indicate that pyrosequencing is effective in understanding the dynamics and functionality of cecal microbial communities in relation to anticoccidial treatment, Eimeria challenge and broiler performances.

Two grazing experiments were designed to elucidate the shifts in rumen bacterial populations (Exp. 1) and grazing activities (Exp. 2) in wheat forage diet between bloated and nonbloated steers. In Exp. 1, the bacterial DNA density was greatest for Ruminococcus flavefaciens, Streptococcus bovis, and Eubacterium ruminantium among tested strains when steers were fed bermudagrass hay (d 0). Steers that grazed wheat forage, however, increased the bacterial density of 6 major rumen bacterial populations in bloated steers, indicating that frothy bloat may be associated with a species-specific bacterial population. In Exp. 2, overall time, total grazing, and ruminating time did not differ between bloated and nonbloated steers. In contrast, idling time was greater for bloated (P < 0.01) than for nonbloated steers (10.9 vs. 7.9 h/d, respectively). Bloated steers did not differ in total grazing activity patterns; however, grazing activity in bloated steers decreased (P < 0.05) from 0400 to 0700h and 1400 to 1800h. Ruminating activity in nonbloated steers peaked from 0200 to 0500h and 1900 to 2200h but was lower (P < 0.05) for bloated than for nonbloated steers from 0100 to 0600h and 0700 to 1200h. The data suggest that rumen bacterial populations and grazing activities changed when steers experienced frothy bloat.

Previous research conducted in our laboratory found a significant prevalence of multi-drug resistant (MDR) Salmonella and MDR Escherichia coli (MDR EC) in dairy calves and suggests that the MDR EC population may be an important reservoir for resistance elements that could potentially transfer to Salmonella. Therefore, the objective of the current research was to determine if resistance transfers from MDR EC to susceptible strains of inoculated Salmonella. The experiment utilized Holstein calves (approximately 3 weeks old) naturally colonized with MDR EC and fecal culture negative for Salmonella. Fecal samples were collected for culture of Salmonella and MDR EC throughout the experiment following experimental inoculation with the susceptible Salmonella strains. Results initially suggested that resistance did transfer from the MDR E. coli to the inoculated strains of Salmonella, with these stains demonstrating resistance to multiple antibiotics following in vivo exposure to MDR EC. However, serogrouping and serotyping results from a portion of the Salmonella isolates recovered from the calves post-challenge, identified two new strains of Salmonella; therefore transfer of resistance was not demonstrated under these experimental conditions.

Coccidiosis causes mucosal damage and predisposes birds to enteropathogen infection. In this study pyrosequencing was used to evaluate effects of coccidiosis on the intestinal microflora of broilers given diets without feed additives or supplemented with either a growth promotant antibiotic and an ionophore, or two essential oil blends. DNA samples were collected from the cecal contents of broilers before (19 d) and after (26 d) infection with mixed Eimeria spp. (E. acervulina, E. maxima and E. tenella). A 454 FLX pyrosequencer and 16S universal primers were used to obtain quantitative profiles of bacterial taxa present in each sample. The relative percent abundance of the identified taxa was analyzed using hierarchical clustering and principal component analysis. Samples from pre-infected broilers were dominated by bacterial species belonging to genera Subdoligranulum, Coprococcus, Alistipes, Lactobacillus and Faecalibacterium. Post-infection samples were dominated by species from the genera Escherichia/Shigella and acteroides. Eimeria infection did not significantly affect the richness of the microbial communities but rather its composition. The composition of the cecal microbiome correlated with the average feed conversion ratio. The methodology used in this study proved effective in understanding the effects of coccidia infection on intestinal microflora of broilers raised on diets supplemented with growth promoting antibiotics, ionophores and essential oils.

The present study was aimed at elucidating the effects of supplementing mannan-oligosaccharides (MOS) and probiotic mixture (PM) on growth performance, intestinal histology, and corticosterone concentrations in broilers kept under chronic heat stress (HS). Four hundred fifty 1-d-old chicks were divided into 5 treatment groups and fed a corn-soybean diet ad-libitum. The temperature control (CONT) group was held at the normal ambient temperature. Heat stress broilers were held at 35 ± 2°C from d 1 until the termination of the study at d 42. Heat stress groups consisted of HS-CONT fed the basal diet; HS-MOS fed the basal diet containing 0.5% MOS; HS-PM fed the basal diet containing 0.1% PM; and HS-SYN (synbiotic) fed 0.5% MOS and 0.1% PM in the basal diet. Broilers were examined at d 21 and 42 for BW gain, feed consumption, feed conversion ratio (FCR), serum corticosterone concentrations, and ileal microarchitecture. The results revealed that the CONT group had higher (P < 0.01) feed consumption, BW gain, and lower FCR on d 21 and 42, compared with the HS-CONT group. Among supplemented groups, the HS-MOS had higher (P < 0.05) BW gain and lower FCR compared with the HS-CONT group. On d 21 and 42, the HS-CONT group had higher (P < 0.05) serum corticosterone concentrations compared with the CONT and supplemented groups. The CONT group had higher (P < 0.05) villus height, width, surface area, and crypt depth compared with the HS-CONT group. On d 21, the HS-PM had higher (P < 0.05) villus width and surface area compared with HS-CONT group. On d 42, the HS-SYN had higher (P < 0.05) villus width and crypt depth compared with the HS-CONT group. These results showed that chronic HS reduces broiler production performance, intestinal microarchitecture, and increases adrenal hormone concentrations. Also, supplementation of the MOS prebiotic and the PM can partially lessen these changes.

Two experiments were conducted to 1) enumerate the effect of tannin supplementation on ADG, bloat frequency, in vitro gas, and biofilm and foam production, and 2) quantify the influence of tannin supplementation on ruminal bacterial populations of heifers grazing wheat forage. Twenty-six heifers (286 ± 26 kg) were randomly allocated to 1 of 3 treatments that included a control (nontannin group) and 2 types of tannins (mimosa and chestnut tannins). Plant tannins (1.5% of DMI) were supplemented once daily mixed with a textured feed (500 g/animal). Heifers were visually monitored daily for bloat score (0 = no bloat, 3 = severe bloat). In Exp. 1, supplementation of tannins reduced the rate of frothy foam and biofilm production with chestnut being more efficacious than mimosa tannins. There was no treatment × time interaction (P > 0.1) for ADG and bloat measurement. Chestnut tannin supplementation increased ADG (P < 0.05) with time (P < 0.01). Mean bloat score and bloat day were greater (P < 0.01) for the control diet than for tannin-supplemented treatment groups. In Exp. 2, Fibrobacter succinogenes, Streptococcus bovis, and Prevotella ruminicola strains were relatively stable with time (d 0, 10, and 25) in the rumen of animals not receiving tannin supplementation. However, with supplementation of chestnut and mimosa tannins, populations of P. ruminicola and strains of both F. succinogenes and Ruminococcus flavefaciens were increased, respectively. Results show that daily supplementing mimosa and chestnut tannins to heifers grazing wheat forage improved beef production and minimized bloat frequency with minimum impact to the microbial populations studied.

Applications of antimicrobials in food production and human health have found favor throughout human history. Antibiotic applications in agricultural and human medical arenas have resulted in tremendous increases in food animal production and historically unprecedented gains in human health protection. Successes attributed to widespread antibiotic use have been accompanied by the inadvertent emergence of antibiotic-resistant bacteria. A major problem associated with this emerging resistance is the crossover use of some antibiotics in agricultural settings as well as in the prevention and treatment of human disease. This outcome led to calls to restrict the use of human health-related antibiotics in food animal production. Calls for restricted antibiotic use have heightened existing searches for alternatives to antibiotics that give similar or enhanced production qualities as highly reliable as the antibiotics currently provided to food animals. Agricultural and scientific advances, mainly within the last 100 yr, have given us insights into sources, structures, and actions of materials that have found widespread application in our modern world. The purpose of this presentation is to provide a historic perspective on the search for what are generally known as antibiotics and alternative antimicrobials, probiotics, prebiotics, bacteriophages, bacteriocins, and phytotherapeutics.