Effect of continuous or intermittent feeding of ergot contaminated grain in a mash or pelleted form on the performance and health of feedlot beef steers.

This study evaluated the effect of feeding ergot contaminated grain continuously or intermittently through backgrounding (BG) and finishing (FN) in a mash or pelleted supplement on the growth performance, health and welfare parameters, and carcass characteristics of feedlot beef steers. Sixty black Angus steers (300 ±â€…29.4 kg BW) were used in a complete randomized 238-d study. Steers were stratified by weight and randomly assigned to four different diets (15 steers/treatment) and individually housed. Treatments included: (1) control [CON; no added ergot alkaloids (EA)], (2) continuous ergot mash (CEM; fed continuously at 2 mg total EA/kg of DM), (3) intermittent ergot mash (IEM; fed at 2 mg total EA/kg of DM, during the first week of each 21-d period and CON for the remaining 2 wk, this feeding pattern was repeated in each period), and (4) intermittent ergot pellet (IEP; fed at 2 mg of total EA/kg of DM as a pellet during the first week of each 21-d period and CON for the remaining 2 wk as described for IEM). Steers were fed barley based BG diets containing 40% concentrate:60% silage (DM basis) for 84 d (four 21-d periods), transitioned over 28 d (no ergot fed) to an FN diet (90% concentrate:10% silage DM basis) and fed for 126 d (six 21-d periods) before slaughter. In the BG phase, steer DMI (P < 0.01, 7.45 vs. 8.05 kg/d) and ADG (P < 0.01) were reduced for all EA diets compared to CON. The CEM fed steers had lower ADG (P < 0.01, 0.735 vs. 0.980 kg) and shrunk final BW (P < 0.01, 350 vs. 366 kg) than CON. CEM had lower gain:feed (P < 0.07, 0.130 vs. 0.142) than CON. In the FN phase, steer DMI (P < 0.01, 9.95 vs. 11.05 kg/d) and ADG (P = 0.04) were also decreased for all EA fed steers compared to CON. Total shrunk BW gain (P = 0.03, 202.5 vs. 225.2 kg), final BW (P = 0.03, 617.9 vs. 662.2 kg), and carcass weight (P = 0.06) decreased for all EA fed steers compared to CON. The percentage of AAA carcasses decreased for all EA fed steers (P < 0.01, 46.7 vs. 93.3%) compared to CON. EA fed steers had increased rectal temperatures (P < 0.01, 39.8 vs. 39.4 °C) compared to CON. Pelleting ergot contaminated grain did not reduce the impact of ergot alkaloids on any of the measured parameters during BG or FN. Continuously or intermittently feeding ergot contaminated diets (2 mg total EA/kg of DM) significantly reduced intake, growth performance, and carcass weight, with minimal impact on blood parameters in feedlot steers. Pelleting was not an effective method of reducing ergot toxicity.

Produced by the fungus Claviceps purpurea, ergot alkaloids (EA) are toxic to beef cattle when consumed and can lead to reduction in feed intake and growth performance, vasoconstriction of the blood vessels, hyperthermia, damage to extremities (ears, tails, and hooves) and in severe cases, death. Grain is often cleaned to meet quality standards, and the resulting screenings are often utilized for feeding livestock and can have high concentrations of EA. The application of heat during pelleting of EA contaminated grain has been suggested to reduce its toxicity. Backgrounding and finishing beef cattle feeding experiments were conducted to assess the effect of continuously or intermittently feeding EA contaminated grain (2 mg/kg of diet DM) either as a pellet or as mash on growth performance, health, and animal welfare. Feeding EA grain continuously or intermittently either as a mash or pellet drastically reduced growth performance of steers, with no difference between treatments.

Evaluating the liver abscess microbiota of beef cattle during a reduction in tylosin supplementation shows differences according to abscess size and fraction.

Liver abscesses (LA) resulting from bacterial infection in cattle pose a significant global challenge to the beef and dairy industries. Economic losses from liver discounts at slaughter and reduced animal performance drive the need for effective mitigation strategies. Tylosin phosphate supplementation is widely used to reduce LA occurrence, but concerns over antimicrobial overuse emphasize the urgency to explore alternative approaches. Understanding the microbial ecology of LA is crucial to this, and we hypothesized that a reduced timeframe of tylosin delivery would alter LA microbiomes. We conducted 16S rRNA sequencing to assess severe liver abscess bacteriomes in beef cattle supplemented with in-feed tylosin. Our findings revealed that shortening tylosin supplementation did not notably alter microbial communities. Additionally, our findings highlighted the significance of sample processing methods, showing differing communities in bulk purulent material and the capsule-adhered material. Fusobacterium or Bacteroides ASVs dominated LA, alongside probable opportunistic gut pathogens and other microbes. Moreover, we suggest that liver abscess size correlates with microbial community composition. These insights contribute to our understanding of factors impacting liver abscess microbial ecology and will be valuable in identifying antibiotic alternatives. They underscore the importance of exploring varied approaches to address LA while reducing reliance on in-feed antibiotics.

Effect of physically effective neutral detergent fiber and undigested neutral detergent fiber on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract digestibility in finishing cattle.

This study evaluated the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract nutrient digestibility for finishing cattle. Six Simmental heifers (668 ± 28.4 kg BW) were used in a replicated 3 × 3 Latin square (21 d periods) balanced for carry-over effects. Treatments included a control (CON; Table 1) with no forage peNDF and minimal uNDF (peNDF: 0.0%, and uNDF: 4.88 ± 0.01; 95.15% barley grain, 4.51% vitamin and mineral supplement, and 0.34% urea on a DM basis). Pelleted wheat straw (PELL) was included at 10% of dietary DM by replacing barley grain to provide added uNDF but no forage peNDF (peNDF: 0.00%, and uNDF: 6.78 ± 0.02%). Finally, chopped wheat straw (STR) was included as a replacement for pelleted wheat straw to provide forage peNDF and uNDF (peNDF: 1.74 ± 0.06%, and uNDF: 6.86 ± 0.03%). Dry matter intake was not affected (P = 0.93) by treatments. Cattle fed CON spent less time ruminating (P = 0.010) and had less meals/d (P = 0.035) when compared with cattle fed STR, with those fed PELL being intermediate but not different from other treatments. Cattle fed CON had lesser ruminal pH (P = 0.020), and a greater duration that pH was < 5.5 (P = 0.020) as compared to cattle fed STR, with those fed PELL being intermediate but not different. Cattle fed CON and PELL had greater total short-chain fatty acid concentration (P = 0.003) and molar proportion of propionate (P < 0.001) when compared with cattle fed STR. Cattle fed STR had greater (P = 0.010) total ruminal pool size when compared with cattle fed CON and PELL. Cattle fed CON had greater (P = 0.043) duration between ruminal contractions when compared with cattle fed STR, with those fed PELL being intermediate. Cattle fed CON had greater serum amyloid A (P = 0.003) and haptoglobin (P < 0.001) concentration when compared with the other treatments. Cattle fed CON had greater dry matter (P < 0.001) digestibility when compared with the other treatments. In conclusion, inclusion of PELL and STR impacted eating behavior, but only STR affected ruminal fermentation, ruminal motility, systemic inflammation, and total tract nutrient digestibility in finishing cattle. These results are interpreted to suggest that the combination of peNDF and uNDF may be better than uNDF alone to adequately capture biological effects of NDF in high-concentrate diets.

Normally forages are included at minimal levels when formulating finishing cattle diets due to lower digestibility and higher operational and economic costs than concentrates. However, insufficient fiber may increase the risk of nutritional disorders such as ruminal acidosis, negatively impacting health, and consequently growth performance of feedlot cattle. An understanding of the minimum forage requirement and the constituent factors that best explain that requirement can help to promote health and performance while minimizing cost. The present study compared the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) in concentrate-based finishing diets. Feeding more peNDF increased ruminating time and ruminal pH, but decreased time between ruminal contractions, total short-chain fatty acid concentration, and the molar proportion of propionate when compared with feeding a diet with minimal peNDF and uNDF. Responses to feeding uNDF with no peNDF were generally intermediate but not different from other treatments. In addition, feeding more peNDF decreased indicators of systemic inflammation and dry matter digestibility when compared with the diet with less peNDF or uNDF. In conclusion, peNDF, or at least the combination of peNDF and uNDF may be better than uNDF alone to stimulate rumination and ruminal motility, thereby stabilizing ruminal pH. Using both peNDF and uNDF may be useful in characterizing the value of fiber in finishing diets fed to feedlot cattle.

A Pine Enhanced Biochar Does Not Decrease Enteric CH4 Emissions, but Alters the Rumen Microbiota.

The objective of this study was to examine the effect of a pine enhanced biochar (EB) on rumen fermentation, apparent total tract digestibility, methane (CH4) emissions, and the rumen and fecal microbiome of Angus × Hereford heifers fed a barley silage-based diet. The experiment was a replicated 4 × 4 Latin square using 8 ruminally cannulated heifers (565 ± 35 kg initial BW). The basal diet contained 60% barley silage, 35% barley grain and 5% mineral supplement with EB added at 0% (control), 0.5, 1.0, or 2.0% (DM basis). Each period lasted 28 days, consisting of 14 days adaptation and 14 days of measurements. Samples for profiling of the microbiome in rumen liquid, solids and feces were collected on d 15 before feeding. Rumen samples for fermentation characterization were taken at 0, 3, 6, and 12 h post feeding. Total collection of urine and feces was conducted from days 18 to 22. Heifers were housed in open-circuit respiratory chambers on days 26-28 to estimate CH4 emissions. Ruminal pH was recorded at 1-min intervals during CH4 measurements using indwelling pH loggers. Data were analyzed with the fixed effects of dietary treatment and random effects of square, heifer within square and period. Dry matter intake was similar across treatments (P = 0.21). Ammonia N concentration and protozoa counts responded quadratically (P = 0.01) to EB in which both were decreased by EB included at 0.5 and 1.0%, compared to the control and 2.0% EB. Minimum pH was increased (P = 0.04), and variation of pH was decreased (P = 0.03) by 2.0% EB. Total tract digestibility, N balance and CH4 production were not affected (P ≥ 0.17) by EB. Enhanced biochar decreased the relative abundance of Fibrobacter (P = 0.05) and Tenericutes (P = 0.01), and increased the relative abundance of Spirochaetaes (P = 0.01), Verrucomicrobia (P = 0.02), and Elusimicrobia (P = 0.02). Results suggest that at the examined concentrations, EB was ineffective at decreasing enteric CH4 emissions, but did alter specific rumen microbiota.

Effects of a recombinant fibrolytic enzyme on fiber digestion, ruminal fermentation, nitrogen balance, and total tract digestibility of heifers fed a high forage diet1.

A metabolism study was conducted using 8 ruminal cannulated beef heifers to investigate the effects of a recombinant fibrolytic enzyme (RFE; xylanase XYL10C) selected specifically for forage-fed ruminants on ruminal pH, fermentation, nitrogen balance, and total tract digestibility of heifers. The experiment was a cross-over design with 2 treatments and 2 periods. The 2 treatments were a basal diet containing 60% barley silage, 30% barley straw, and 10% supplement (DM basis) without (control) or with RFE. The enzyme was sprayed onto the barley straw at a rate of 6.6 × 104 IU·kg-1 DM 24 h before feeding. Each period comprised 2 wk of diet adaptation and 1 wk of sampling and data collection. Feed intake and total tract digestibility of DM, OM, NDF, and ADF were unaffected by RFE. Ruminal pH including mean, minimum, maximum, and duration pH <5.8, did not differ between treatments. Total VFA concentration, molar proportion of individual VFA, and acetate-to-propionate ratio were also not affected by RFE. However, ruminal NH3-N concentration (P < 0.06) and endoglucanase activity (P < 0.08) in ruminal fluid tended to be higher with RFE. Nitrogen utilization and microbial protein synthesis were not affected by treatment. These results indicate that XYL10C did not improve fiber digestion in heifers fed a high forage diet, despite the fact that it was specifically selected for this trait in laboratory assays. However, the increased ruminal NH3-N concentration suggests it potentially increased ruminal proteolytic activity.

Impact of a phytogenic feed additive on growth performance, feed intake, and carcass traits of finishing steers.

The purpose of this study was to evaluate the effect of a phytogenic feed additive (Digestarom [DA]; Biomin, Getzersdorf, Austria) on growth performance, feed intake, carcass traits, fatty acid composition, and liver abscesses of finishing steers. One hundred twenty Angus × Charolais crossbred steers (488 ± 26.5 kg) were used in a 110-d feeding experiment. Steers were blocked by weight and randomly assigned to 12 pens with 10 steers per pen. Each pen was allocated to one of three diets. Each diet contained 86.5% barley, 10.0% barley silage, and 3.5% vitamin and mineral supplement on a dry matter (DM) basis. The diets contained 0, 0.05, and 0.1 g DA/kg complete diet (DM basis), to achieve average daily DA intakes of 0 (control), 0.5 (LowDA), and 1.0 g (HighDA) per steer. Diets were prepared once daily and provided ad libitum. Two pens per treatment were equipped to record individual feed intake behavior. Steers were weighed every 28 d and carcass traits and liver scores were recorded at slaughter. Dry matter intake (average: 9.34 kg/d) did not differ (P > 0.05) among diets. Average daily gain tended to increase linearly as DA increased (control: 1.82; LowDA: 1.87; and HighDA: 1.95 kg/d; P < 0.09), but gain:feed ratio was not affected. Supplementation of DA affected longissimus muscle area quadratically (P = 0.05) with the largest area observed for LowDA. However, dressing percentage decreased linearly in response to increasing level of DA (P < 0.01). Total abscessed livers were not affected, whereas proportion of severe liver abscesses was numerically lower with DA (30.8% and 42.5% for LowDA and HighDA) compared to the control (50%).

Effects of Condensed and Hydrolyzable Tannins on Rumen Metabolism with Emphasis on the Biohydrogenation of Unsaturated Fatty Acids.

The hypothesis that condensed tannins have higher inhibitory effect on ruminal biohydrogenation than hydrolyzable tannins was tested. Condensed tannin extract from mimosa (CT) and hydrolyzable tannin extract from chestnut (HT) or their mixture (MIX) were incorporated (10%) into oil supplemented diets and fed to rumen fistulated sheep. Fatty acid and dimethyl acetal composition of rumen contents and bacterial biomass were determined. Selected rumen bacteria were analyzed by quantitative real time PCR. Lower ( P < 0.05) rumen volatile fatty acids concentrations were observed with CT compared to HT. Moreover, lower concentration ( P < 0.05) of Fibrobacter succinogenes, Ruminococcus flavefaciens, Ruminococcus albus, and Butyrivibrio proteoclasticus were observed with CT compared to HT. The extension of biohydrogenation of 18:2n-6 and 18:3n-3 did not differ among treatments but was much more variable with CT and MIX than with HT. The trans-/ cis-18:1 ratio in bacterial biomass was higher ( P < 0.05) with HT than CT. Thus, mimosa condensed tannins had a higher inhibitory effect on ruminal metabolism and biohydrogenation than chestnut hydrolyzable tannins.

Inactivation of Escherichia coli O157 Bacteriophages by Using a Mixture of Ferrous Sulfate and Tea Extract.

Bacteriophages (phages) have been used for biocontrol of Escherichia coli O157 and other pathogenic bacteria in many different matrices and foods, but few studies have included inactivation of residual phages in culture medium before plating and enumeration of surviving host bacteria for the assessment of phage efficacy. This oversight may lead to overestimation of phage efficacy. The ability of virucidal solution containing a mixture of ferrous sulfate [iron(II) sulfate, FeSO4] and tea extract [Fe(II)T] to inactivate residual T5-like, T1-like, T4-like, and rV5-like phages was assessed using E. coli O157 as the host. At concentrations of ≥10 mM FeSO4, all phages were not detected after 20 min in a broth culture model. Compared with the virucidal solution-free samples (1 to 96% recovery), Fe(II)T (10 mM FeSO4 plus 15% tea extract) recovered a greater (P < 0.01) number of E. coli O157 from phage-treated broth culture (97 to 100% recovery) and beef samples (52 to 100% recovery). Moreover, with the addition of Fe(II)T, the number of bacteria surviving after exposure to T5-like or T4-like phages was greater (P < 0.01) than that after exposure to T1-like or rV5-like phages. Consequently, use of a virucide for phage inactivation is recommended to improve the accuracy of evaluations of phage efficacy for biocontrol of E. coli O157.

Effects of essential oils from medicinal plants acclimated to Benin on in vitro ruminal fermentation of Andropogon gayanus grass.

BACKGROUND: Plants from West Africa commonly used in both human and veterinary medicine contain various secondary metabolites. However, their potential in mitigating ruminal methane production has not been explored. This study examined the effects of seven essential oils (EOs) from plants acclimated to Benin at four dosages (100, 200, 300 and 400 mg L(-1)), on in vitro rumen microbial fermentation and methane production using Andropogon gayanus grass as a substrate. RESULTS: Compared to control, Laurus nobilis (300-400 mg L(-1) ), Citrus aurantifolia (300-400 mg L(-1)) and Ocimum gratissimum (200-400 mg L(-1)) decreased (P < 0.05) methane production (mL g(-1) DM) by 8.1-11.8%, 11.9-17.8% and 7.9-30.6%, respectively. Relative to the control, reductions in methane (mL g(-1) DM) of 11.4%, 13.5% and 14.2% were only observed at 400 mg L(-1) for Eucalyptus citriodora, Ocimum basilicum and Cymbopogon citratus, respectively. These EOs lowered methane without reducing concentrations of total volatile fatty acids or causing a shift from acetate to propionate production. All EOs (except M. piperita) reduced (P < 0.05) apparent dry matter (DM) disappearance of A. gayanus. CONCLUSIONS: The current study demonstrated that EOs from plants grown in Benin inhibited in vitro methane production mainly through a reduction in apparent DM digestibility.

Endemic bacteriophages: a cautionary tale for evaluation of bacteriophage therapy and other interventions for infection control in animals.

BACKGROUND: One of the most effective targets for control of zoonotic foodborne pathogens in the farm to fork continuum is their elimination in food animals destined for market. Phage therapy for Escherichia coli O157:H7 in ruminants, the main animal reservoir of this pathogen, is a popular research topic. Since phages active against this pathogen may be endemic in host animals and their environment, they may emerge during trials of phage therapy or other interventions, rendering interpretation of trials problematic. METHODS: During separate phage therapy trials, sheep and cattle inoculated with 109 to 1010 CFU of E. coli O157:H7 soon began shedding phages dissimilar in plaque morphology to the administered therapeutic phages. None of the former was previously identified in the animals or in their environment. The dissimilar "rogue" phage was isolated and characterized by host range, ultrastructure, and genomic and proteomic analyses. RESULTS: The "rogue" phage (Phage vB_EcoS_Rogue1) is distinctly different from the administered therapeutic Myoviridae phages, being a member of the Siphoviridae (head: 53 nm; striated tail: 152x8 nm). It has a 45.8 kb genome which is most closely related to coliphage JK06, a member of the "T1-like viruses" isolated in Israel. Detailed bioinformatic analysis reveals that the tail of these phages is related to the tail genes of coliphage lambda. The presence of "rogue" phages resulting from natural enrichments can pose problems in the interpretation of phage therapeutic studies. Similarly, evaluation of any interventions for foodborne or other bacterial pathogens in animals may be compromised unless tests for such phages are included to identify their presence and potential impact.

Effects of cinnamon leaf, oregano and sweet orange essential oils on fermentation and aerobic stability of barley silage.

BACKGROUND: Silage additives are marketed with the primary aim of improving the fermentation and/or aerobic stability of silage. The objective of this study was to evaluate the impact of three different essential oils (EOs; cinnamon leaf (CIN), oregano (ORE) and sweet orange (SO)) on the fermentation characteristics and stability of barley silage. Chopped whole-plant barley (Hordem vulgare L.) forage was ensiled either untreated (0 mg kg⁻¹ dry matter (DM)) or treated with CIN, ORE or SO (37.5, 75 and 120 mg kg⁻¹ DM). RESULTS: Moulds were not detected in any treatments, including the control, after 7 days of air exposure. All EOs at a concentration of 120 mg kg⁻¹ silage DM decreased (P = 0.001) yeast populations in comparison with the control during air exposure. Net gas, methane and ammonia concentrations in vitro did not differ among treatments. Changes in volatile fatty acid concentrations were small, and in situ data showed no changes in DM and neutral detergent fibre digestion rates for CIN, ORE or SO at concentrations up to 120 mg kg⁻¹ DM. CONCLUSION: The findings from this study show that a concentration of 120 mg EO kg⁻¹ DM decreased yeast counts during aerobic stability tests. However, all EO treatments had minimal effects on data from in vitro and in situ incubations.

Beef quality attributes as affected by increasing the intramuscular levels of vitamin E and omega-3 fatty acids.

In order to investigate the effects of increasing beef n-3 fatty acid content and the protective effects of vitamin E antioxidant activity on meat quality characteristics, 80 feedlot steers were fed 4 different diets (control, high vitamin E, 10% ground flaxseed or high vitamin E-10% ground flaxseed). While dietary treatments had no effect (P>0.05) on meat composition or tenderness values, the increase in oxidation products was lower (P=0.046) in meat from vitamin E supplemented steers and higher (P=0.006) in meat from flaxseed fed animals. The increase in α-tocopherol tissue levels (P<0.001) in meat from animals fed flaxseed and increased dietary vitamin E resulted in the lowest drip loss values (P=0.013). As expected, display time had a large effect on retail traits in both steaks and patties (P<0.001). While retail traits of steaks were not affected by the dietary treatments (P>0.05), feeding flaxseed decreased (P<0.05) ground beef retail scores, which were not corrected by higher levels of dietary vitamin E. Finally, although no effect (P>0.05) was observed among treatments for sensory attributes in steaks, the correlations of a combined n-3:α-tocopherol ratio against retail and sensory attributes (P<0.05) suggest that increased n-3 fatty acids levels require increased dietary antioxidants, such as vitamin E to avoid negative effects on meat quality from a loss in oxidative stability.

Effects of vitamin E and flaxseed on rumen-derived fatty acid intermediates in beef intramuscular fat.

To elucidate the effects of dietary vitamin E with or without flaxseed on beef fatty acid composition, 80 feedlot steers were fed 4 diets: Control-E (451 IU dl-α-tocopheryl acetate/head/day), Control+E (1051 IU dl-α-tocopheryl acetate/head/day), Flax-E (10% ground) and Flax+E. Vitamin E had no effect on animal growth or carcass weight (p>0.05), while flaxseed-fed steers had greater average daily gain (p=0.007), final live weight (p=0.005) and heavier carcasses (p=0.012). Feeding flaxseed increased the total n-3 fatty acid content of beef and this response was further accentuated by the inclusion of high levels of vitamin E in the diet. Feeding flax increased levels of some 18:3n-3 partial hydrogenation products including c15- and t13/14-18:1 and several 18:2 isomers (p<0.001) but decreased t10-18:1 (p<0.001). Vitamin E enhanced intramuscular levels of 18:3n-3 and its biohydrogenation products leading to greater accumulations of total n-3 fatty acids in lean ground beef. The consequences of increasing the concentrations of partially hydrogenated products on human health have yet to be investigated.

Fermentation characteristics of corn-, triticale-, and wheat-based dried distillers' grains with solubles in barley-based diets determined using continuous and batch culture systems.

BACKGROUND: Dried distillers' grains with solubles (DDGS) are becoming increasingly available and popular as an alternative livestock feed. This study used continuous and batch culture techniques to compare the in vitro fermentation characteristics of diets containing corn-, triticale- or wheat-based DDGS at 200 g kg(-1) diet dry matter (DM) against a barley grain-based control diet. RESULTS: In continuous fermentation of wheat DDGS diet, total volatile fatty acid (VFA) concentration was decreased by 15.7% across sampling times and NH(3) concentration was quadrupled compared with control, whereas fermentations of corn- and triticale-DDGS diets were similar to the barley-based control. In batch cultures, corn DDGS differed from control only in increased culture pH. Compared with control diet, triticale DDGS yielded lower total gas production (140.94 versus 148.78 mL g(-1) DM) and in vitro DM digestibility (IVDMD; 0.509 versus 0.535). Wheat DDGS diet yielded decreased total gas production (123.49 mL g(-1) DM) and IVDMD (0.468), as well as total VFA production (105.84 versus 134.20 mmol L(-1)) and substantially increased ammonia concentration (151.61 versus 58.34 mg L(-1)) and acetate:propionate ratio (2.94 versus 1.11). CONCLUSION: Corn- and triticale- DDGS diets exhibited fermentation characteristics similar to the barley based control diet, consistent with in vivo findings that these diets yielded no adverse effects on production. In vitro ruminal fermentation of wheat DDGS diet differed significantly from control in several aspects including 2.6 to 6X higher ammonia concentrations.

A modified spectrophotometric assay to estimate deglycosylation of steroidal saponin to sapogenin by mixed ruminal microbes.

BACKGROUND: The lack of a method for measuring deglycosylation of saponins in ruminal fluid has limited the ability to investigate the impact of these compounds on rumen microorganisms. A simple spectrophotometric assay was adapted and a protocol developed to enable measurement of steroidal saponin and sapogenin in ruminal fluid. The procedure was used for in vitro determination of deglycosylation activity of rumen bacteria obtained from cattle fed or not fed Yucca schidigera saponin, and to determine the relative deglycosylase activities of extracellular and cell-associated enzymes from ruminal content. RESULTS: Modifications to the spectrophotometric assay (i.e. heating time shortened to 10 min and 0.5 mL dH(2)O added to the reaction mixture) improved the stability of the optical density (425 nm) of the chromophore for up to 24 h post-reaction. Centrifugation (12 000 x g, 20 min) enabled differential estimations of steroidal saponin and sapogenin in ruminal fluid. Steroidal saponin added to defaunated ruminal fluid (dRF) or clarified ruminal fluid (cRF) was recovered completely from the mixture as saponin + sapogenin (99.1% and 100.6%, respectively), whereas saponin recovery from the supernatant of dRF was greatly reduced (P < 0.001) compared to that from supernatant of cRF (58.5 vs. 98.7%). Saponin recoveries from the supernatants of dRF and cRF did not differ between donor cattle fed or not fed Yucca schidigera saponin (59.2 vs. 57.3% and 98.4 vs. 99.3%, respectively). The majority (89-90%) of saponin added to a ruminal extracellular enzyme preparation was recoverable in supernatant after 24 h, compared with only 26-32% remaining in supernatant from incubation with a cell-associated enzymes fraction. CONCLUSION: Mixed rumen bacteria deglycosylate steroidal saponin to sapogenin, at activity levels unaffected by prior exposure to saponin, but they were unable to degrade the sapogenin core structure. Deglycosylation activity occurred primarily in the cell-associated enzyme fraction of ruminal content.

Oral and rectal administration of bacteriophages for control of Escherichia coli O157:H7 in feedlot cattle.

This study compared oral and rectal administration of O157-specific bacteriophages for mitigating the fecal shedding of Escherichia coli O157 by experimentally inoculated steers. Fecal shedding of nalidixic acid-resistant (Nal(R)) E. coli O157:H7 was monitored over 83 days after oral (ORL; 3.3 x 10(11) PFU), rectal (REC; 1.5 x 10(11) PFU), both oral and rectal (O+R; 4.8 x 10(11) PFU), or no (CON; control) treatment with a four-strain O157-specific bacteriophage cocktail in multiple doses. Bacteriophages were enumerated by plaque assay, and NalR E. coli O157:H7 by direct plating on sorbitol MacConkey agar supplemented with cefixime, potassium tellurite, and nalidixic acid. Orally treated steers produced the fewest Nal(R) E. coli O157:H7 culture-positive samples (P < 0.06) compared with REC and O+R steers, but this number was only nominally lower (P = 0.26) than that for the CON steers. The overall mean shedding level (log CFU per gram of feces) was higher for REC steers (P < 0.10) than for steers of the other treatment groups. Despite the shedding of higher mean bacteriophage levels (log PFU per gram of feces) by ORL and O+R than by CON and REC steers, there was no difference (P > 0.05) in the number of E. coli O157-positive samples among treatments. Bacteriophage was isolated from CON steers, indicating that these steers acquired the bacteriophage from the environment and shed the phage at a level similar to that of REC steers (P = 0.39). Continuous bacteriophage therapy may be an efficacious method for mitigating shedding of E. coli O157:H7 in cattle, providing that the host bacterium does not develop resistance. This therapy may be especially advantageous if nontreated cattle can acquire this biocontrol agent from the feedlot environment.

Physical and chemical changes during composting of wood chip-bedded and straw-bedded beef cattle feedlot manure.

In the 1990s, restrictions on incineration encouraged the forest industry in western Canada to develop new uses for their wood residuals by product. One such use was as a replacement for cereal straw bedding in southern Alberta's beef cattle (Bos taurus) feedlot industry. However, use of carbon (C)-rich bedding, such as wood chips, had implications for subsequent composting of the feedlot manure, a practice that was being increasingly adopted. In a 3-yr study, we compared composting of wood chip-bedded manure (WBM) and barley (Hordeum vulgare L.) straw-bedded manure (SBM). There were no significant differences in temperature regimes of SBM and WBM, indicating similar rates of successful composting. Of 17 physical and chemical parameters, five showed significant (P < 0.10) differences due to bedding at the outset of composting (Day 0), and 11 showed significant differences at final sampling (Day 124). During composting (10 sampling times), seven parameters showed significant bedding effects, 16 showed significant time effects, and four showed a Bedding x Time interaction. Significantly lower (P < 0.10) losses of nitrogen (N) occurred with WBM (19%) compared with SBM (34%), which has positive implications for air quality and use as a soil amendment. Other advantages of WBM compost included significantly higher total C (333 vs. 210 kg Mg(-1) for SBM) and inorganic N (1.3 vs. 1.0 kg Mg(-1) for SBM) and significantly lower total phosphorus (4.5 vs. 5.3 kg Mg(-1) for SBM). Our results showed that wood chip bedding should not be a problem for subsequent composting of the manure after pen cleaning. In combination with other benefits, our findings should encourage the adoption of wood chips over straw as a bedding choice for southern Alberta feedlots.

Acute interstitial pneumonia in feedlot cattle: effects of feeding feather meal or vitamin E.

We evaluated the effects of feeding 1.5% cysteine-rich feather meal or 550 IU of vitamin E for 40 d before slaughter on the rates of death and emergency slaughter due to acute interstitial pneumonia (AIP) in commercial feedlots. Blood and lung tissue were collected at slaughter from 83 animals clinically diagnosed with AIP, 40 asymptomatic penmates, and 40 heifers receiving either feather meal (20) or vitamin E (20); the left lung was subsampled for histologic examination. Blood and lung tissue were analyzed for thiol adducts of 3-methyleneindolenine (3ME) and reduced glutathione. Supplementation with feather meal or vitamin E had no effect on the rates of death and emergency slaughter attributable to AIP and did not influence the levels of 3ME or reduced glutathione in blood or lung tissue. Although supplementation with greater amounts of feather meal or vitamin E may have been necessary to significantly affect factors related to feedlot AIP, increased supplementation would be uneconomical for commercial feedlots, given the relatively low incidence of AIP.

Bedding and within-pen location effects on feedlot pen runoff quality using a rainfall simulator.

Soluble salts, nutrients, and pathogenic bacteria in feedlot-pen runoff have the potential to cause pollution of the environment. A 2-yr study (1998-1999) was conducted at a beef cattle (Bos taurus) feedlot in southern Alberta, Canada, to determine the effect of bedding material [barley (Hordeum vulgare L.) straw versus wood chips] and within-pen location on the chemical and bacterial properties of pen-floor runoff. Runoff was generated with a portable rainfall simulator and analyzed for chemical content (nitrogen [N], phosphorus [P], soluble salts, electrical conductivity [EC], sodium adsorption ratio [SAR], dissolved oxygen [DO], and pH) and populations of three groups of bacteria (Escherichia coli, total coliforms, total aerobic heterotrophs at 27 degrees C) in 1998 and 1999. Bedding had a significant (P < or = 0.05) effect on NH4-N concentration and load in 1999, SO4 load in 1998, SO4 concentration and load in 1999, and total coliforms in both years; where these three variables were higher in wood than straw pens. Location had a significant effect on EC and concentrations of total Kjeldahl nitrogen (TKN), Na, K, SO4, and Cl in 1998, and total coliforms in both years. These seven variables were higher at the bedding pack than pen floor location, indicating that bedding packs were major reservoirs of TKN, soluble salts, and total coliforms. Significantly higher dissolved reactive phosphorus (DRP), total P, and NH4-N concentrations and loads at the bedding pack location in wood pens in 1998, and a similar trend for TKN concentration in 1999, indicated that this bedding-location treatment was a greater source of nutrients to runoff than the other three bedding-location treatments. Bedding, location, and their interaction may therefore be a potential tool to manage nutrients, soluble salts, and bacteria in feedlot runoff.

Bedding and seasonal effects on chemical and bacterial properties of feedlot cattle manure.

Nutrients, soluble salts, and pathogenic bacteria in feedlot-pen manure have the potential to cause pollution of the environment. A three-year study (1998-2000) was conducted at a beef cattle (Bos taurus) feedlot in southern Alberta, Canada to determine the effect of bedding material [barley (Hordeum vulgare L.) straw versus wood chips] and season on the chemical and bacterial properties of pen-floor manure. Manure was sampled for chemical content (N, P, soluble salts, electrical conductivity, and pH) and populations of four groups of bacteria (Escherichia coli, total coliforms, and total aerobic heterotrophs at 27 and 39 degrees C). More chemical parameters of manure were significantly (P < or = 0.05) affected by season (SO4, Na, Mg, K, Ca, sodium adsorption ratio [SAR], total C, NO3-N, NH4-N, total P, and available P) than by bedding (K, pH, total C, C to N ratio, NH4-N, and available P). Bedding had no significant (P > 0.05) effect on the four bacterial groups whereas season affected all four groups. Numbers of E. coli and total coliforms (TC) were significantly higher by 1.72 to 2.02 log10 units in the summer than the other three seasons, which was consistent with a strong positive correlation of E. coli and TC with air temperature. The low ratio of bedding to manure in the pens was probably the major cause of the lack of significant bedding effects. Bedding material and seasonal timing of cleaning feedlot pens and land application of manure may be a potential tool to manage nutrients, soluble salts, and pathogens in manure.