Quality and precision processing of barley grain affected intake and digestibility of dry matter in feedlot steers

2013 ◽  
Vol 93 (2) ◽  
pp. 251-260 ◽  
Author(s):  
W. Z. Yang ◽  
M. Oba ◽  
T. A. McAllister
Keyword(s):  
Digestive Tract ◽  
Dry Matter ◽  
Latin Square ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Ruminal Ph ◽  
Feedlot Steers ◽  
Acid Detergent Fibre ◽  
Barley Silage ◽  
The Impact

Yang, W. Z., Oba, M. and McAllister, T. A. 2013. Quality and precision processing of barley grain affected intake and digestibility of dry matter in feedlot steers. Can. J. Anim. Sci. 93: 251–260. A study was conducted to determine the impact of barley quality and precision processing to account for the impact of variable kernel uniformity on ruminal pH and fermentation, and digestibility in the digestive tract of steers. Eight ruminally cannulated steers were used in a replicated 4×4 Latin square experiment. The four diets consisted of light-weight barley (LB) precision-processed with roller setting based on kernel size; heavy-weight barley (HB) precision-processed; LB and HB grain mixed equal parts then processed at a single roller setting (CON); or LB and HB precision-processed and mixed equal parts (PP). The diets consisted of 10% barley silage and 90% concentrate [dry matter (DM) basis]. Dry matter intake by steers fed LB was greater (P=0.04) than by steers fed HB. Intakes of DM and other nutrients were greater (P=0.04) for steers fed PP than for steers fed CON. There were no differences (P>0.14) in ruminal pH and fermentation among treatments. Digestibility of DM in the total digestive tract tended (P=0.06) to be less with LB than with HB. Precision processing increased digestibility of crude proteion (P=0.04) and acid detergent fibre (P=0.06) resulting in a trend (P=0.10) towards increasing organic matter digestibility as compared with CON. The results suggest that screening of blended barley into more uniform fractions and precision processing of each fraction could increase intake of digestible nutrients for feedlot cattle.

PSX-B-10 Effect of undigested neutral detergent fiber concentration and forage inclusion rate on ruminal pH, reticular motility, and total tract permeability for finishing beef heifers

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 457-458
Author(s):  
Murillo C Pereira ◽  
Karen A Beauchemin ◽  
Tim A McAllister ◽  
Wenzhu Yang ◽  
Joyce Van Donkersgoed ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Dry Matter ◽  
Latin Square ◽  
Barley Grain ◽  
Neutral Detergent Fiber ◽  
Fiber Concentration ◽  
Eating Time ◽  
Ruminal Ph ◽  
Contraction Duration ◽  
Gastrointestinal Permeability

Abstract This study evaluated the effects of undigested neutral detergent fiber (uNDF) concentration and forage inclusion (FI) rate on dry matter (DM) intake, ruminal pH, reticular contractions, and gastrointestinal permeability for finishing beef cattle. Five ruminally cannulated Hereford′Simmental heifers (699±69.1 kg) were used in an incomplete 6×6 Latin square (26-d periods) with a 2×3 factorial treatment arrangement. Barley grain-based diets were formulated using barley silage or wheat straw to provide low or high uNDF (7.1 vs. 8.5% DM) with forage proportions of 5, 10, or 15% of dietary DM. Dry matter intake (P ≥ 0.10) and eating time (P ≥ 0.13) were not affected by uNDF, FI, or uNDF′FI. With low uNDF diets, increasing FI numerically (P = 0.02) increased rumination time (min/d); while, with high uNDF diets, rumination time increased with 5 to 10% FI, but not thereafter (P = 0.03). Mean ruminal pH was not affected by uNDF (6.17 vs. 6.19; P = 0.08), but increased with increasing FI (6.04b, 6.23a, and 6.28a; P = 0.02). Duration of ruminal pH < 5.5 was not affected by uNDF but tended (P = 0.07) to be reduced with increasing FI. High uNDF diet tended to increase the frequency of reticular contractions (1.43 vs. 1.51 contractions/min; P = 0.07) but decreased the contraction duration (13.2 vs. 14.1 sec; P = 0.04). Increasing FI increased contraction frequency (1.39b, 1.50a, and 1.53a contractions/min; P = 0.03) and tended to reduce contraction duration as forage increased from 5 to 10 and 15% (14.3, 13.1, and 13.6 sec; P = 0.07). Feeding high uNDF decreased (P = 0.05) permeability of the gastrointestinal tract based on the appearance of Cr-EDTA in urine following an intra-ruminal dose. Increasing FI tended to reduce gastrointestinal tract permeability (P = 0.06). Limited interactions indicate that uNDF and FI act independently suggesting that increasing dietary uNDF, without increasing FI rate, can stimulate frequency of reticulo-ruminal contractions and reduce gastrointestinal permeability for finishing cattle.

Impact of a mixed culture of Lactobacillus casei and L. lactis on in vitro ruminal fermentation and the growth of feedlot steers fed barley-based diets

2009 ◽  
Vol 89 (2) ◽  
pp. 263-271 ◽  
Author(s):  
J. Baah ◽  
Y. Wang ◽  
T A McAllister
Keyword(s):  
Growth Performance ◽  
Mixed Culture ◽  
Lactobacillus Casei ◽  
Carcass Characteristics ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Ruminal Fermentation ◽  
Feedlot Steers ◽  
Barley Silage

The effect of a direct-fed microbial (DFM) poduct containing a mixed culture of Lactobacillus casei and L. lactis on in vitro ruminal fermentation of barley-grain/barley-silage-based backgrounding and finishing diets and on growth performance and carcass characteristics of feedlot cattle was evaluated during backgrounding (84 d) and finishing (140 d) of 100 Hereford × Angus steers (initial body weight = 280 ± 15.5 kg). The inclusion rates of DFM in the in vitro study were 4, 8, 12 and 16 million colony forming units (CFU) of lactic acid bacteria (LAB) kg-1 DM of substrate. Total in vitro volatile fatty acids (VFA) production increased at 6 and 12 h of incubation (P < 0.01; linear response) when the backgrounding diet was supplemented with DFM. Dry matter digestibility and VFA production also increased (P < 0.05) during a 12-h fermentation of the finishing diet. Steers were randomly allocated to one of four dietary treatments that comprised feeding DFM tp provide 0 (control), 4 × 107, 8 × 107, or 12 × 107 CFU kg-1 diet DM. Average daily gain (ADG, kg) and feed efficiency (G:F; kg gain kg-1 DM consumed) of steers improved (P = 0.002 and 0.001, respectively) as a result of feeding DFM during the backgrounding period, but not during the finishing period. Saleable meat and rib eye area decreased (P = 0.038, linear; and P = 0.041, quadratic) with DFM supplementation. The results indicated that supplementing barley-grain/barley-silage-based feedlot cattle diets with 12 × 107 CFU of the mixed culture of lactobacilli used in these studies could improve ruminal fermentation, ADG and G:F in backgrounding feedlot steers. However, supplementation during the finishing period may not be warranted in terms of growth performance and carcass characteristics. Differences in the microbial ecology of the intestinal tract as a result of differences in diet composition may account for the varied response between the backgrounding and finishing periods.Key words: Beef cattle, direct-fed microbial, growth performance, Lactobacillus casei, Lactobacillus lactis, ruminal fermentation

scholarly journals Optimum roughage proportion in barley-based feedlot cattle diets: growth performance, feeding behavior, and carcass traits

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Karen M Koenig ◽  
Gwinyai E Chibisa ◽  
Gregory B Penner ◽  
Karen A Beauchemin
Keyword(s):  
Feeding Behavior ◽  
Growth Performance ◽  
Dry Matter ◽  
Carcass Traits ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Experimental Unit ◽  
Finishing Diets ◽  
Ruminal Acidosis ◽  
Barley Silage

Abstract High grain diets are fed to finishing beef cattle to maximize animal performance in a cost-effective manner. However, a small amount of roughage is incorporated in finishing diets to help prevent ruminal acidosis, although few studies have examined optimum roughage inclusion level in barley-based diets. The objective of the study was to evaluate the effects of roughage proportion in barley-based finishing diets on growth performance, feeding behavior, and carcass traits of feedlot cattle. Crossbred beef steers (n = 160; mean body weight ± SD, 349.7 ± 21.4 kg) were allocated to 20 pens that were assigned randomly to four dietary treatments (five pens of eight steers per treatment). The treatment diets contained barley silage at 0%, 4%, 8%, and 12% of dietary dry matter (DM). The remainder of the diets (DM basis) consisted of 80%, 76%, 72%, and 68% barley grain, respectively, 15% corn dried distiller’s grains, 5% mineral and vitamin supplement, and 32 mg monensin/kg diet DM. The diets were fed as total mixed rations for ad libitum intake (minimum of 5% refusal) once per day. Cattle were weighed on 2 consecutive days at the start and end of the experiment and on 1 d every 3 wk throughout the experiment (124 d). Two pens for each treatment group were equipped with an electronic feeding system (GrowSafe Systems Ltd., Calgary, Alberta) to monitor feed intake and feeding behavior of individual cattle. The data for dry matter intake (DMI), average daily gain (ADG), gain:feed (G:F) ratio, and carcass traits were analyzed as a completely randomized design with fixed effect of barley silage proportion and pen replicate as experimental unit. Feeding behavior data were analyzed similarly, but with animal as experimental unit. Averaged over the study, DMI increased linearly (11.1, 11.3, 11.7, 11.8 kg/d; P = 0.001) as barley silage proportion increased from 0%, 4%, 8%, and 12% of DM, but ADG was not affected (carcass-adjusted,1.90, 1.85, 1.87, 1.89 kg/d; P ≥ 0.30). Consequently, G:F ratio decreased linearly (carcass-adjusted, 168.9, 163.8, 158.5, 160.6 g/kg DMI; P = 0.023). When averaged over the study, proportion of barley silage in the diet had no linear or quadratic effects (P &gt; 0.10) on meal frequency, duration of meals, intermeal duration, or meal size, but eating rate decreased linearly with increasing silage proportion (P = 0.008). There was no diet effect on liver abscesses (P ≥ 0.92), and effects on carcass characteristics were minor or nonexistent. We conclude that increasing the proportion of barley silage in a feedlot finishing diet at the expense of barley grain to minimize the incidence of ruminal acidosis may decrease feed conversion efficiency.

Canola screenings as a fiber source in barley-based feedlot diets: effects on rumen fermentation and performance of steers

2000 ◽  
Vol 80 (1) ◽  
pp. 161-168 ◽  
Author(s):  
S. J. Pylot ◽  
J. J. McKinnon ◽  
T. A. McAllister ◽  
A. F. Mustafa ◽  
J. Popp ◽  
...  
Keyword(s):  
Control Diet ◽  
Latin Square ◽  
Dietary Treatment ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Beef Steers ◽  
Ruminal Fermentation ◽  
Finishing Diets ◽  
And Performance ◽  
Barley Silage

Two experiments were conducted to determine the feeding value of canola screenings in combination with barley grain for beef steers. Four dietary treatments were used. These included canola screenings:barley grain ratios of 100:0; 75:25, 50:50, and 25:75 (as-fed basis). In a metabolic trial, the effects of dietary treatment on ruminal fermentation parameters were determined in a 4 × 4 Latin square design experiment using four ruminally fistulated steers. In a production trial, 66 individually fed steers were used in an 83-d finishing trial to determine the performance and carcass characteristics of feedlot cattle fed different levels of canola screenings. A barley grain/barley silage-based control diet was also fed for comparison purposes. Ruminal pH decreased (P < 0.05) while total volatile fatty acid concentrations increased (P < 0.05) as the level of barley grain in the diet increased. Ruminal NH3–N followed a pattern (P < 0.05) similar to that of pH. Inclusion level of canola screenings had no effect on DM intake. However, ADG and feed efficiency increased (P < 0.05) as the level of barley grain in the diet increased. Increasing the level of barley grain in the finishing diet decreased (P < 0.05) lean meat yield and increased (P < 0.05) carcass fat. It was concluded that canola screenings can be included as a source of fiber in barley-based diets. However, levels in excess of 500 g kg−1 reduced the performance of feedlot steers. Performance and cost of gain with 250 and 500 g kg−1 canola screenings in barley-based finishing diets were comparable with those fed an 800 g kg−1 barley grain and 200 g kg−1 barley silage diet. Key words: Canola screenings, ruminal fermentation, feedlot steer performance

scholarly journals Use of corn distillers’ dried grains to reduce enteric methane loss from beef cattle

2009 ◽  
Vol 89 (3) ◽  
pp. 409-413 ◽  
Author(s):  
S M McGinn ◽  
Y -H Chung ◽  
K A Beauchemin ◽  
A D Iwaasa ◽  
C Grainger
Keyword(s):  
Beef Cattle ◽  
Dry Matter ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Sulphur Hexafluoride ◽  
Distillers Dried Grains ◽  
Enteric Methane ◽  
Gross Energy ◽  
Corn Distillers ◽  
The Impact

There are significant emissions of greenhouse gases (GHG) from agriculture, and a major source is enteric methane (CH4) from ruminants. Our study reports the impact on enteric CH4 emissions when barley grain (35% of the dietary dry matter (DM) was replaced by corn distillers’ dried grains with solubles (DDGS, adding 30 g fat kg-1 dietary DM) in the backgrounding diet of growing beef cattle. The addition of DDGS reduced CH4 emissions (g d-1) by 19.9%, and by 16.4% when adjusted for DM intake [g (DM intake)-1] or by 23.9% when adjusted for gross energy (GE) intake (% of GE intake). Adding DDGS to cattle diets reduced CH4 emissions, but the effects of higher N content of the manure on emissions of nitrous oxide and ammonia need to be accounted for to complete the evaluation of the environmental impact of feeding DDGS to feedlot cattle. Key words: Methane, beef cattle, corn distillers’ dried grains with solubles, lipid, greenhouse gas emissions, sulphur hexafluoride

scholarly journals 200 Effects of grain processing and undegradable fiber on rumen pH and fermentation of cattle fed high grain diets

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 159-160
Author(s):  
Tao Ran ◽  
A M Saleem ◽  
Karen Beauchemin ◽  
G Penner ◽  
Wenzhu Yang
Keyword(s):  
Latin Square ◽  
Barley Grain ◽  
Finishing Cattle ◽  
Mineral Supplements ◽  
Ruminal Ph ◽  
Grain Processing ◽  
Rumen Ph ◽  
Rumen Acidosis ◽  
Barley Silage ◽  
Finishing Beef Cattle

Abstract The objective of this study was to investigate the effects of processing index (PI, weight after processing/weight before processing × 100) of barley grain and dietary undegradable fiber (uNDF, 240 h of incubation in rumen) concentration on DM intake (DMI), ruminal pH and fermentation characteristics of finishing beef cattle. Six ruminally cannulated beef heifers (BW, 715 ± 29 kg) were used in a 6 × 6 Latin square design with 3 PI (65, 75 and 85%; fine, medium, coarse, respectively) × 2 uNDF concentrations (low and high; 4.6 vs. 5.6% of DM) factorial arrangement. Heifers were fed ad libitum a diet consisting of 10% barley silage (low uNDF), or 5% silage and 5% straw (high uNDF), 87% dry-rolled barley, and 3% vitamin and mineral supplements. An interaction of PI × uNDF was observed (P &lt; 0.01) for DMI, but not for mean or duration of rumen pH &lt; 5.8 or &lt; 5.6 over a 24-h period. The DMI (kg/d) was greater (P &lt; 0.05) for high (12.7) versus low (12.1) uNDF diets with 85% PI, with no difference in DMI (average, 12.1) between low and high uNDF diets with 65 or 75% PI. The duration of pH &lt; 5.8 (14.6 versus 13.3 h) and pH &lt; 5.6 (10.8 versus 8.6 h) reduced (P &lt; 0.05) for high versus low uNDF diets. The PI did not affect total volatile fatty acid (tVFA) concentration or molar proportions of individual VFA, but the tVFA was less (172 and 162 mM; P &lt; 0.01) and acetate proportion was greater (46.0 and 48.2%; P &lt; 0.01) with high versus low uNDF. These results indicate that increasing dietary uNDF concentration is an effective strategy to improve ruminal pH status in finishing cattle, regardless of extent of grain processing, whereas minimizing the extent of grain processing did not reduce the risk of rumen acidosis.

Effects of distillers’ dried grains with solubles from corn, wheat or a 50:50 corn:wheat blend on performance, carcass characteristics and serum sulphate levels of feedlot steers

2012 ◽  
Vol 92 (3) ◽  
pp. 343-351 ◽  
Author(s):  
S. Amat ◽  
S. Hendrick ◽  
T. A. McAllister ◽  
H. C. Block ◽  
J. J. McKinnon
Keyword(s):  
Dry Matter ◽  
Control Diet ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Barley Grain ◽  
Barley Straw ◽  
Partial Replacement ◽  
Distillers Dried Grains ◽  
Feedlot Steers ◽  
Barley Silage

Amat, S., Hendrick, S., McAllister, T. A., Block, H. C. and McKinnon, J. J. 2012. Effects of distillers’ dried grains with solubles from corn, wheat or a 50:50 corn:wheat blend on performance, carcass characteristics and serum sulphate levels of feedlot steers. Can. J. Anim. Sci. 92: 343–351. Two trials were conducted to evaluate the effects of corn (CDDGS), wheat (WDDGS) or a 50:50 corn:wheat blend (BDDGS) dried distillers’ grains with solubles (DDGS) on performance (Trials 1 and 2), carcass traits (Trial 2) and serum sulphate level (Trial 2) of steers. In Trial 1, 396 steers (281.1±19.6 kg) were fed one of three backgrounding diets. The control diet was 34.3% barley grain, 26.0% grass hay, 10.3% barley straw, 22.8% barley silage and 6.7% supplement [dry matter (DM) basis]. For the two treatments, 17% of the barley was replaced with CDDGS or WDDGS. In Trial 2, 288 steers (273.9±18.5 kg) were backgrounded and finished. Backgrounding diets were identical to Trial 1, with a third treatment where 17% of the barley grain was replaced with BDDGS. The control finishing diet was 86.8% barley grain, 7.4% barley silage and 5.8% supplement (DM basis). Treatments included replacement of 40% of the barley grain (DM basis) with CDDGS, BDDGS or WDDGS. In Trial 1, there was no effect of DDGS on dry matter intake (DMI) (P=0.49), average daily gain (ADG) (P=0.64), feed efficiency (P=0.06), ultrasound fat (USFAT) (P=0.90) or longissimus dorsi (USLD) (P=0.071) area. In Trial 2, overall, DMI of cattle fed WDDGS was higher (P=0.03) than control or CDDGS cattle, with BDDGS intermediate. In contrast, ADG was higher (P<0.01) for the CDDGS and BDDGS than either the control or WDDGS fed cattle. The CDDGS and BDDGS cattle were more efficient (P<0.01) than those fed WDDGS with the controls intermediate. Cattle fed CDDGS or WDDGS exhibited higher (P<0.01) serum sulphate levels compared with BDDGS or control cattle, reflecting differences in sulphur intake. The results indicate that CDDGS is a superior energy source to WDDGS and that both sources of DDGS can be used as a partial replacement for barley in backgrounding and finishing diets for cattle.

scholarly journals Effects of forage inclusion and cattle breed on apparent digestibility and ruminal pH of steers fed a whole shelled corn-based diet

2021 ◽  
Author(s):  
Pedro H V Carvalho ◽  
Mariana F Westphalen ◽  
Flavia A S Silva ◽  
Tara L Felix
Keyword(s):  
Repeated Measures ◽  
Dry Matter ◽  
Latin Square ◽  
Cattle Breed ◽  
Dry Matter Intake ◽  
Sample Collection ◽  
Ruminal Ph ◽  
Collection Data ◽  
The Impact ◽  
Plot Design

Abstract Objectives were to evaluate the effects of cattle breed, Holstein or Angus, and forage inclusion on total tract digestibility and ruminal pH in cattle fed a whole shelled corn (WSC) based diet. Six Holstein and 6 Angus steers, were assigned to a 2 × 3 factorial arrangement of treatments. Factors included breed, Holstein or Angus, and forage inclusion at 0, 8, or 16% forage (dry matter (DM) basis). Steers were fed in a replicated 3 × 3 Latin square, split-plot design. Each period consisted of 14 d diet adaptation followed by 7 d of sample collection. Data were analyzed using the MIXED procedures in SAS (v9.4 SAS Inst. Inc., Cary, NC). Repeated measures were used to analyze changes in ruminal pH over time. There was no interaction of breed × diet (P ≥ 0.19) on dry matter intake (DMI) or digestibility; however, Holstein steers had greater (P = 0.03) DMI than Angus steers. Despite the impact of breed on intake, there was no effect (P ≥ 0.33) of breed on diet digestibility. Digestibility of DM increased (linear; P &lt; 0.01) as forage was removed from the diet, but there were no differences (P ≥ 0.32) in NDF and starch digestibility. However, due to the change in diet, NDF intake digested on a grams per day basis increased (P ≤ 0.01) and starch intake digested (g/d) decreased (P = 0.01) as forage inclusion increased. There was a tendency for breed × diet interaction (P = 0.08) on ruminal pH. Holstein steers fed 8% or 16% forage had greater ruminal pH than Holstein steers fed 0% forage; but, ruminal pH of Angus steers was not altered by diet.

Optimum extent of barley grain processing and barley silage proportion in feedlot cattle diets: Growth, feed efficiency, and fecal characteristics

2011 ◽  
Vol 91 (3) ◽  
pp. 411-422 ◽  
Author(s):  
Karen Koenig ◽  
Karen Beauchemin
Keyword(s):  
Conversion Efficiency ◽  
Feed Efficiency ◽  
Dry Matter ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Feed Conversion ◽  
Feed Conversion Efficiency ◽  
Grain Processing ◽  
Final Weight ◽  
Barley Silage

Koenig, K. M. and Beauchemin, K. A. 2011. Optimum extent of barley grain processing and barley silage proportion in feedlot cattle diets: Growth, feed efficiency and fecal characteristics. Can. J. Anim. Sci. 91: 411–422. A study was conducted to evaluate the effects of forage proportion and extent of processing of barley grain on growth, intake, feed conversion efficiency, and fecal characteristics of feedlot cattle. Crossbred steers (120; 407±31 kg) were housed individually and assigned to 10 diets (n=12): two degrees of temper rolling of barley grain [processing index (PI) of 82% (standard) or 87% (coarse)] were combined with five levels of barley silage [3, 6, 9, 12, and 15% of dietary dry matter (DM)]. The PI was determined as the weight of grain after processing expressed as a percentage of the weight before processing. Cattle were slaughtered after 104–109 d on feed, at a final weight of 576 kg, SEM = 5.1. There were very few interactions between grain processing and silage proportion for the variables measured. Grain processing had no effect (P>0.05) on average daily gain (1.59 kg d−1, SEM = 0.057) or final weight. Feeding PI-87% barley tended to increase dry matter intake (DMI) over the experiment (7.63 vs. 7.34 kg d−1, SEM = 0.123, P=0.10) compared with feeding PI-82% barley. Higher DMI of cattle fed PI-87% barley corresponded to lower estimated starch digestibility, as a result of increased appearance of whole kernels and grain fragments in feces. Consequently, gain:feed ratio tended (0.210 vs. 0.219, SEM = 0.0035, P=0.06) to decrease by 4% with PI-87% versus PI-82% barley. Similarly, silage proportion had no effect on gain but DMI increased (P=0.05) linearly from 7.19 to 7.75 kg d−1 (SEM = 0.194) with increasing proportion of silage. Consequently, gain:feed ratio decreased linearly from 0.225 to 0.202 (SEM = 0.0056) with increasing silage proportion. Optimum proportion of barley silage to maximize feed conversion efficiency was 3 to 6% of DM. Decreasing the extent of barley processing or increasing the silage proportion may reduce the risk of acidosis, but feed conversion efficiency is lowered. Formulating diets to reduce the incidence of digestive disorders may decrease the cost of mortalities and treatment of sick animals, thereby improving animal health and welfare, but these costs are unlikely to offset the increased cost of gain in commercial feedlots.

scholarly journals Effect of Subtherapeutic Administration of Antibiotics on the Prevalence of Antibiotic-Resistant Escherichia coli Bacteria in Feedlot Cattle

2008 ◽  
Vol 74 (14) ◽  
pp. 4405-4416 ◽  
Author(s):  
T. W. Alexander ◽  
L. J. Yanke ◽  
E. Topp ◽  
M. E. Olson ◽  
R. R. Read ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Environmental Factors ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Antibiotic Resistant ◽  
Fecal Samples ◽  
E Coli ◽  
Feedlot Steers ◽  
Escherichia Coli Bacteria ◽  
Barley Silage

ABSTRACT Antibiotic-resistant Escherichia coli in 300 feedlot steers receiving subtherapeutic levels of antibiotics was investigated through the collection of 3,300 fecal samples over a 314-day period. Antibiotics were selected based on the commonality of use in the industry and included chlortetracycline plus sulfamethazine (TET-SUL), chlortetracycline (TET), virginiamycin, monensin, tylosin, or no antibiotic supplementation (control). Steers were initially fed a barley silage-based diet, followed by transition to a barley grain-based diet. Despite not being administered antibiotics prior to arrival at the feedlot, the prevalences of steers shedding TET- and ampicillin (AMP)-resistant E. coli were >40 and <30%, respectively. Inclusion of TET-SUL in the diet increased the prevalence of steers shedding TET- and AMP-resistant E. coli and the percentage of TET- and AMP-resistant E. coli in the total generic E. coli population. Irrespective of treatment, the prevalence of steers shedding TET-resistant E. coli was higher in animals fed grain-based compared to silage-based diets. All steers shed TET-resistant E. coli at least once during the experiment. A total of 7,184 isolates were analyzed for MIC of antibiotics. Across antibiotic treatments, 1,009 (13.9%), 7 (0.1%), and 3,413 (47.1%) E. coli isolates were resistant to AMP, gentamicin, or TET, respectively. In addition, 131 (1.8%) and 143 (2.0%) isolates exhibited potential resistance to extended-spectrum β-lactamases, as indicated by either ceftazidime or cefpodoxime resistance. No isolates were resistant to ciprofloxacin. The findings of the present study indicated that subtherapeutic administration of tetracycline in combination with sulfamethazine increased the prevalence of tetracycline- and AMP-resistant E. coli in cattle. However, resistance to antibiotics may be related to additional environmental factors such as diet.

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