Beef Feedlot Research Articles

Açai seed as a fiber source in high-concentrate beef cattle diets and its nutritional effects

This study evaluated the effects of different levels of inclusion of coarsely broken açai seed (CBAS) in the diet of feedlot beef cattle on the intake, digestibility, ruminal degradation, passage kinetics, and nitrogen utilization efficiency. Five ruminally fistulated crossbred bulls (387±27kg body weight) were used in a 5×5 Latin square design. A total mixed ration with 750g/kg concentrate and 250g/kg roughage, based on the total dry matter (DM), was used. The treatments consisted of the inclusion of CBAS at 0, 50, 100, 150, and 200g/kg DM as a fiber source in the diet. The roughage used was Mombasa grass silage, which was partially replaced by CBAS. A linear increase in organic matter (OM; P=0.042), crude protein (CP; P=0.023), and neutral detergent fiber (NDF; P=0.022) intake was observed with the inclusion of CBAS in the diet, while a linearly increasing trend was observed for DM (P=0.077) and metabolizable energy (ME; P=0.051) intake. The total, ruminal, and intestinal digestibility of DM and nutrients were not affected by the inclusion of CBAS (P > 0.10). Ruminal ammonia nitrogen decreased linearly (P=0.045), while acetate concentration showed a linear increase (P=0.038), propionate was not affected (P=0.762), and butyrate showed a linear tendency to increase (P=0.086) with the inclusion of CBAS. Passage rate and DM degradation, as well as N utilization were not affected by the inclusion of CBAS (P > 0.10), except for N fecal excretion that showed a linear tendency to increase (P=0.092). Thus, we conclude that CBAS increases organic matter, crude protein, metabolizable energy, and neutral detergent fiber intake in high-concentrate diets without compromising rumen kinetics and nitrogen utilization in beef cattle. Therefore, the CBAS can be considered as an alternative roughage source in scenarios where forage silage of low quality is the fiber source.

Prevalence of Foodborne Pathogens in Pacific Northwest Beef Feedlot Cattle Fed Two Different Direct-Fed Microbials

In recent years, there has been an increased interest in beef cattle shedding of foodborne pathogens due to the potential to contaminate surrounding food crops; however, the number of studies published on this topic has declined as the majority of research has emphasized on postharvest mitigation efforts. A field study was conducted to determine the prevalence of pathogens and indicator bacteria in beef cattle fed two different direct-fed microbials (DFMs). Fecal samples from a total of 3,708 crossbred yearling cattle randomly assigned to 16 pens and two treatment groups at a commercial cattle feedlot were taken. During the study period, diets were supplemented with two different DFMs i.) Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24) (9 log10CFU/head/day), and ii.) Lactobacillus salivarius (L28) (6 log10CFU/head/day). Fecal samples from pen floors were collected on days 0, 21, 42, 63, 103, and analyzed for the presence of Salmonella and E. coli O157:H7 and concentration of E. coli O157:H7, Enterobacteriaceae, and C. perfringens. Fecal samples collected from cattle fed L28 had significantly lower concentration of C. perfringens (p < 0.05) and had a similar prevalence with no significant differences in E. coli O157:H7 as those fed NP51/NP24 through the study until day 103. On day 103, the prevalence in cattle fed L28 was 40% with a concentration of 0.95 log10MPN/g while those fed NP51/NP24 were 65% with a concentration of 1.2 log10MPN/g. Cattle supplemented with NP51/NP24 achieved a significant log reduction of EB by 2.4 log10CFU/g over the course of the 103-day supplementation period compared to L28. Salmonella prevalence was also measured, but not detected in any samples at significant amounts to draw conclusions. It is evident that E. coli O157:H7 and other foodborne pathogens are still prevalent in cattle operations and that preharvest mitigation strategies should be considered to reduce the risk to beef products.

Inferential implications of normalizing binomial proportions in a structural equation model: A simulation study motivated by feedlot data.

Most commercial software for implementation of structural equation models (SEM) cannot explicitly accommodate outcome variables of binomial nature. As a result, SEM modeling strategies of binomial outcomes are often based on normal approximations of empirical proportions. Inferential implications of these approximations are particularly relevant to health-related outcomes. The objective of this study was to assess the inferential implications of specifying a binomial variable as an empirical proportion (%) in predictor and outcome roles in a SEM. We addressed this objective first by a simulation study, and second by a proof-of-concept data application on beef feedlot morbidity to bovine respiratory disease (BRD). We simulated data on body weight at feedlot arrival (AW), morbidity count for BRD (Mb), and average daily gain (ADG). Alternative SEMs were fitted to the simulated data. Model 1 specified a directed acyclic causal diagram with morbidity fitted as a binomial outcome (Mb) and as a proportion (Mb_p) predictor. Model 2 specified a similar causal diagram with morbidity fitted as a proportion for both outcome and predictor roles within the network. Structural parameters for Model 1 were accurately estimated based on the nominal coverage probability of 95 % confidence intervals. In turn, there was poor coverage for most morbidity-related parameters under Model 2. Both SEM models showed adequate empirical power (>80 %) to detect parameters not equal to zero. Model 1 and Model 2 produced predictions that were reasonable from a management standpoint, as determined by calculating the root mean squared error (RMSE) through cross-validation. However, interpretability of parameter estimates in Model 2 was impaired due to the model misspecification relative to the data generation. The data application fitted SEM extensions, Model 1*and Model 2*, to a dataset from a group of feedlots in the Midwestern US. Models 1*and 2*included explanatory covariates, specifically percent shrink (PS), backgrounding type (BG), and season (SEA). Lastly, we tested if AW exerted both direct and BRD-mediated indirect effects on ADG using Model 2*. In Model 1*, mediation was not testable due to the incomplete path from morbidity as a binomial outcome through Mb_p as a predictor to ADG. Model 2*supported a minor morbidity-mediated mechanism between AW and ADG, though parameter estimates were not directly interpretable. Our results indicate normal approximation to a binomial disease outcome in a SEM may be a viable option for inference on mediation hypotheses and for predictive purposes, despite limitations in interpretability due to inherent model misspecification.

Phylogeny, Virulence, and Antimicrobial Resistance Gene Profiles of Enterococcus faecium Isolated from Australian Feedlot Cattle and Their Significance to Public and Environmental Health.

The extent of similarity between E. faecium strains found in healthy feedlot beef cattle and those causing extraintestinal infections in humans is not yet fully understood. This study used whole-genome sequencing to analyse the antimicrobial resistance profile of E. faecium isolated from beef cattle (n = 59) at a single feedlot and compared them to previously reported Australian isolates obtained from pig (n = 60) and meat chicken caecal samples (n = 8), as well as human sepsis cases (n = 302). The E. faecium isolated from beef cattle and other food animal sources neither carried vanA/vanB responsible for vancomycin nor possessed gyrA/parC and liaR/liaS gene mutations associated with high-level fluoroquinolone and daptomycin resistance, respectively. A small proportion (7.6%) of human isolates clustered with beef cattle and pig isolates, including a few isolates belonging to the same sequence types ST22 (one beef cattle, one pig, and two human isolates), ST32 (eight beef cattle and one human isolate), and ST327 (two beef cattle and one human isolate), suggesting common origins. This provides further evidence that these clonal lineages may have broader host range but are unrelated to the typical hospital-adapted human strains belonging to clonal complex 17, significant proportions of which contain vanA/vanB and liaR/liaS. Additionally, none of the human isolates belonging to these STs contained resistance genes to WHO critically important antimicrobials. The results confirm that most E. faecium isolated from beef cattle in this study do not pose a significant risk for resistance to critically important antimicrobials and are not associated with current human septic infections.

Atmospheric transport of particulate matter and particulate-bound agrochemicals from beef cattle feedlots: Human health implications for downwind agricultural communities

Beef cattle feedlot particulate matter (PM) is a complex mixture of dust, animal waste, agrochemicals, and bioaerosols. However, no empirical data exist quantifying downwind residential exposure to PM or PM-bound agrochemicals. In the current study, authors investigated transport of PM and co-occurring insecticides and anthelmintics downwind of three feedlots in the Southern Great Plains (SGP) of North America from May–August 2022. PM collected on total suspended particulate (TSP) filters was analyzed via UHPLC-MS/MS for six pyrethroids and five macrocyclic lactones (MLs). Downwind TSP concentrations rapidly declined from 0.01 to ≤1.6 km (Monte Carlo mean ± SEM; 5049 ± 96.1 μg/m3) and stabilized >1.6–12.4 km (1791 ± 9.9; μg/m3). Distance decay >1.6 km indicated downwind PM exceeded levels of safe human exposure during diurnal peak periods. Pyrethroids and MLs were detected >LOQ in 96.2 and 98.1 % of downwind samples. Screening-level cumulative residential exposure indicates elevated pyrethroid risk (LOC = 1; RI = 0.173) to rural children (1–2 yrs) living near cropland operations in the SGP, with disproportionate co-exposure to feedlot PM and legacy pollution in low-income, Hispanic and Latino communities. Frequent occurrence and sustained transport of pyrethroids downwind of feedlots facilitate residue accumulation in outdoor residential areas that must also be quantified to assess the magnitude of daily average and lifetime-adjusted oral and dermal exposure in surrounding communities. Results significantly expand the known distribution of feedlot-derived PM and agrochemicals and highlight human exposure pathways unrecognized in residential human health assessments supporting pesticide registration and feedlot risk evaluation.

Genomic Characterization of Carbapenem-Resistant Bacteria from Beef Cattle Feedlots.

Carbapenems are considered a last resort for the treatment of multi-drug-resistant bacterial infections in humans. In this study, we investigated the occurrence of carbapenem-resistant bacteria in feedlots in Alberta, Canada. The presumptive carbapenem-resistant isolates (n = 116) recovered after ertapenem enrichment were subjected to antimicrobial susceptibility testing against 12 different antibiotics, including four carbapenems. Of these, 72% of the isolates (n = 84) showed resistance to ertapenem, while 27% of the isolates (n = 31) were resistant to at least one other carbapenem, with all except one isolate being resistant to at least two other drug classes. Of these 31 isolates, 90% were carbapenemase positive, while a subset of 36 ertapenem-only resistant isolates were carbapenemase negative. The positive isolates belonged to three genera; Pseudomonas, Acinetobacter, and Stenotrophomonas, with the majority being Pseudomonas aeruginosa (n = 20) as identified by 16S rRNA gene sequencing. Whole genome sequencing identified intrinsic carbapenem resistance genes, including blaOXA-50 and its variants (P. aeruginosa), blaOXA-265 (A. haemolyticus), blaOXA-648 (A. lwoffii), blaOXA-278 (A. junii), and blaL1 and blaL2 (S. maltophilia). The acquired carbapenem resistance gene (blaPST-2) was identified in P. saudiphocaensis and P. stutzeri. In a comparative genomic analysis, clinical P. aeruginosa clustered separately from those recovered from bovine feces. In conclusion, despite the use of selective enrichment methods, finding carbapenem-resistant bacteria within a feedlot environment was a rarity.

Dispersal and Risk Factors for Airborne Escherichia coli in the Proximity to Beef Cattle Feedlots

California Leafy Green Products Handler Marketing Agreement (LGMA) established food safety metrics with guidance recommendations of 366 m (1,200 feet) and 1,609 m (1 mile) distances between production fields of leafy greens and a concentrated animal feeding operation (CAFO) containing >1,000 and >80,000 head of cattle, respectively. This study evaluated the effect of these distance metrics and environmental factors on the occurrence of airborneEscherichia coliin proximity to seven commercial beef cattle feedlots located in Imperial Valley, California. A total of 168 air samples were collected from seven beef cattle feedlots during March and April 2020, which were the months implicated in the 2018 Yuma Arizona lettuce outbreak of E. coli O157:H7. The distance between air sampling sites and the edge of the feedlot ranged from ∼0 to ∼2,200 m (∼1.3 mile), with each sample comprised of 1,000 L of processed air taken at a 1.2 m elevation over a 10-minute duration. E. colicolonies were enumerated on CHROMagar ECC selective agar and confirmed with conventional PCR. Meteorological data (air temperature, wind speed, wind direction, relative humidity) were collectedin situ. The prevalence and mean concentration ofE. coliwere 6.55% (11/168) and 0.09 CFU per 1,000 L of air, with positive samples limited to within 37 m (120 ft) of the feedlot.Based on logistic regression, the odds of airborne E. coli detection were associated with little to no wind and close proximity to a feedlot. This pilot study found limited dispersal of airborne E. coli in proximity to commercial feedlots in Imperial Valley, with light-to-no wind and proximity within 37 m of a feedlot significant factor-associated airborne E. coli in this produce-growing region of California.

135 Growth Performance, Carcass Characteristics, and Methane Emissions of Feedlot Young Bulls

Abstract The growth performance, carcass characteristics, and methane emissions from feedlot beef cattle fed a high-lipid finishing diet (7.3% of ether extract) were evaluated. Fifty long-yearling young bulls were divided into two groups following their breed composition: Nellore (n = 25) and Angus × Nellore crossbred (n = 25), and randomly assigned into 4 pens (12 or 13 animals/pen) following a completely randomized design. Animals were sourced from the same breeding season and endured a grazing growing phase in Megathyrsus maximus cv. Mombaça pasture, with protein and energy supplement offered at 0.2% of body weight (BW). The feedlot phase comprehended 105 days of feed, and the diet (80% concentrate) was formulated to meet or safely exceed the beef cattle requirements to target an average daily gain (ADG) of 1.6 kg/day, in which major ingredients were represented by (% DM basis): sorghum silage (20%), ground corn (57.6%), ground soybean seed as the lipid source (20.4%), and a mineral/vitamin premix (2%). Titanium dioxide (TiO2) was used as an external marker to estimate dry matter intake (DMI), while 10 g was administered to 12 animals of each group, once daily, for 10 d. Animals were weighed every 30 d after a 16-h fasting period, and the day before slaughter to obtain the final body weight (FBW). Enteric methane emissions were measured using the sulfur hexafluoride (SF6) tracer gas technique in the same animals used for intake measurements. The animals were equipped with gas collection halters attached to pre-evacuated polyvinyl chloride (PVC) sampling canisters with a capillary tube (0.127 mm diameter), made to permit 50% filling in 24 h, for five consecutive days. Data were analyzed using the statistical analysis software R (R CORE TEAM, 2021), and the effect of breed on carcass traits and methane emissions was evaluated using the completely randomized design one-way, in which treatment means were compared by the F test (P &amp;lt; 0.05). The crossbred animals had a greater DMI (12.6 vs.0.6 kg/d), gain efficiency (0.16 vs. 0.14), initial BW upon feedlot phase (509.8 vs. 444.7 kg), FBW (720.8 vs. 595.6, kg), ADG (2.01 vs..44 kg), and hot carcass weight (404.7 vs. 345.0 kg; P &amp;lt; 0.01) compared with Nellore cattle. No difference was observed in dressing percentage between genetic groups (P = 0.28). Nellore animals produced more methane expressed as CH4 g/kg ADG (266.0 vs.73.4; P &amp;lt; 0.01), and tended to produce more methane expressed as CH4 kg/DMI (35.4 vs. 27.7; P = 0.08), and CH4 g/kg CW (1.09 vs. 0.87; P = 0.11). Crossbred F1 Nellore/Angus young bulls showed improved feedlot performance and carcass weight, while not negatively affecting total CH4 production, but rather lessening CH4 emissions per unit of beef produced.

DM intake by feedlot beef cattle: factors that impact intake patterns.

DM intake (DMI) for individual pens of cattle is recorded daily or averaged across each week by most commercial feedlots as an index of performance. Numerous factors impact DMI by feedlot cattle. Some are available at the start of the feedlot period (initial BW, sex), and others become available early in the feeding period (daily DMI during adaptation) or more continuously (daily DMI from the previous week). To evaluate the relative impact of these factors on daily DMI during individual weeks within the feedlot period, we employed a dataset compiled from 2009 to 2014 from one commercial feedlot, including 4132 pens (485458 cattle), which were split into two fractions: 80% were used to calculate DMI regressions on these factors to develop a prediction equation for mean DMI for each week of the feeding period, and 20% were reserved to test the adequacy of these prediction equations. Correlations were used to determine the relationship between all available variables with observed DMI. These variables were then included in the generalized least squares regression models. A veracity test of the model was performed against the reserved data. Daily DMI from previous week was the factor most highly correlated with daily DMI (P<0.10) during from week 6 to week 31, accounting for approximately 70% of the variation, followed by mean daily DMI during adaptation period (weeks 1-4), including in the prediction model from weeks 5 to 12. Initial shrunk BW (ISBW) was the third most correlated factor, which was included in prediction equations from week 5 to week 20. Sex entered the prediction model only after week 8. Daily DMI for each test week within the feeding period was predicted closely (r2=0.98) by these four factors (RMSE=0.155kg). In conclusion, the mean daily DMI during each week of the finishing period for a pen of cattle could be predicted closely based on mean daily DMI intake during the previous week plus other variables available early in a feedlot period (daily DMI during adaptation period, ISBW and sex).

Low to Zero Concentrations of Airborne Bacterial Pathogens and Indicator E. coli in Proximity to Beef Cattle Feedlots in Imperial Valley, California.

This study characterized the effect of distance from beef cattle feedlots, environmental factors, and climate on the occurrence of airborne bacterial indicators and pathogens. Three hundred air samples were collected over 6 months from five feedlots, with each air sample comprising 6000 L of air. Air samples were processed onto TSB-enriched air filters, qPCR-screened, and then qPCR-confirmed for suspect positive colonies of E. coli O157, non-O157-Shiga-toxin-producing E. coli (STEC), Salmonella, and E. coli. Direct enumeration of E. coli was also collected. Although no bacterial pathogens were qPCR-confirmed for the 300 samples, E. coli was detected in 16.7% (50/300) of samples, with an overall mean concentration of 0.17 CFU/6000 L air. Logistic regression analyses revealed a higher odds of E. coli for samples in close proximity compared to >610 m (2000 ft) distance from feedlots, along with significant associations with meteorological factors, sampling hour of day, and the presence of a dust-generating activity such as plowing a field or nearby vehicular traffic. The lack of bacterial pathogen detection suggests airborne deposition from nearby feedlots may not be a significant mechanism of leafy green bacterial pathogen contamination; the result of our study provides data to inform future revisions of produce-safety guidance.

Bronchopneumonia with interstitial pneumonia in beef feedlot cattle: Characterization and laboratory investigation.

Bronchopneumonia with interstitial pneumonia (BIP) has been considered a variant of acute interstitial pneumonia (AIP) rather than a distinct disease. This study compared 18 BIP, 24 bronchopneumonia (BP), and 13 AIP cases in feedlot beef cattle. Grossly, BIP cases typically had cranioventral lung lesions of similar morphology and extent as BP cases, but the caudodorsal lung appeared overinflated, bulged on section, and had interlobular edema and emphysema. Gross diagnosis of BIP had 83% sensitivity and 73% specificity relative to histopathology. Histologic lesions of BIP in cranioventral areas were of chronic BP, while caudodorsal lesions included alveolar and bronchiolar damage and inflammation, interstitial hypercellularity, and multifocal hemorrhages. In BIP cases, cranioventral lung lesions were more chronic than caudodorsal lesions. Histologic scores and microbiology data were comparable in cranioventral lung of BIP versus BP cases and caudodorsal lung of BIP versus AIP cases, with differences reflecting a more chronic disease involving less virulent bacteria in BIP versus BP. Mycoplasma bovis infection was similarly frequent among groups, and a viral cause of BIP was not identified. Lesion morphology and similar blood cytokine concentrations among groups argued against sepsis as a cause of lung injury. Surfactant dysfunction was identified in BIP and BP, and was only partially the result of protein exudation. These and other findings establish BIP as a distinct condition in which chronic cranioventral BP precedes acute caudodorsal interstitial lung disease, supporting a role of chronic inflammation in heightened sensitivity to 3-methylindole or another lung toxicant.

Effect of probiotic lactobacilli supplementation on growth parameters, blood profile, productive performance, and fecal microbiology in feedlot cattle

Lactic acid bacteria (LAB) selected on the basis of probiotic characteristics were administered to beef feedlot catlle and the effect on body condition/growth and nutritional-metabolic status as well as on E. coli O157:H7 fecal shedding, were investigated. A feeding trials involving 126 steers were used to evaluate the effects of Lactobacillus acidophilus CRL2074, Limosilactobacillus fermentum CRL2085 and Limosilactobacillus mucosae CRL2069 and their combinations (5 different probiotic groups and control) when 107-108 CFU/animal of each probiotic group were in-feed supplemented. Cattle were fed a high energy corn-based diet (16 to 88%) and samples from each animal were taken at 0, 40, 104 and 163 days. In general, animals body condition and sensorium state showed optimal muscle-skeletal development and behavioral adaption to confinement; no nasal/eye discharges and diarrheic feces were observed. The nutritional performance of the steers revealed a steady increase of biometric parameters and weight. Animals supplied with L. mucosae CRL2069 for 104 days reached the maximum mean live weight (343.2 kg), whereas the greatest weight daily gain (1.27 ± 0.16 Kg/day) was obtained when CRL2069 and its combination with L. fermentum CRL2085 (1.26 ± 0.11 kg/day) were administered during the complete fattening cycle. With several exceptions, bovine cattle blood and serum parameters showed values within referential ranges. As a preharvest strategy to reduce Escherichia coli O157:H7 in cattle feces, CRL2085 administered during 40 days decreased pathogen shedding with a reduction of 43% during the feeding period. L. fermentum CRL2085 and L. mucosae CRL2069 show promise for feedlot cattle feeding supplementation to improve metabolic-nutritional status, overall productive performance and to reduce E. coli O157:H7 shedding, thus decreasing contamination chances of meat food products.

Effects of a novel direct-fed microbial on growth performance, carcass characteristics, nutrient digestibility, and ruminal morphology of beef feedlot steers.

The effects of a novel direct-fed microbial (DFM) on feedlot performance, carcass characteristics, digestibility, ruminal morphology, and volatile fatty acid (VFA) profile of finishing steers were evaluated. Single-source Angus-crossbred yearling steers (n = 144; initial body weight (BW) = 371 ± 19kg) were used in a randomized complete block design. Steers were blocked by initial BW and randomly assigned to treatments (12 pens/treatment; 4 steers/pen). Treatments included (A) CONTROL (no DFM, tylosin, or monensin, (B) MONTY (monensin sodium [330mg/animal-daily] and tylosin phosphate [90mg/animal-daily]), and (C) MONPRO (monensin sodium [same as previous] and Lactobacillus salivarius L28 [1 × 106 CFU/animal-daily]). Treatments were included in a steam-flaked corn-based finisher diet offered once daily using a clean-bunk management for ~149d. The digestibility assessment was performed from days 70 to 74. Ruminal fluid and rumen tissue samples were collected at the slaughter for VFA profile and papillae morphology analyses, respectively. Data were analyzed using the GLIMMIX procedure of SAS with pen serving as the experimental unit, treatment as fixed effect, and BW block as random effect. Steers offered MONPRO had on average 5.3% less (P < 0.01) dry matter intake (9.56kg/d) compared with either CONTROL (10.16kg/d) or MONTY (9.96kg/d). The carcass-adjusted final BW (613kg; P = 0.23), overall average daily gain (1.64kg/d; P = 0.23), and gain-efficiency (0.165; P = 0.61) were not affected by treatments. Steers offered CONTROL had greater (P < 0.01) marbling score and tended (P = 0.06) to have less carcasses grading Select and tended (P = 0.10) to have more carcasses grading Upper-Choice, while other carcass characteristics and liver-abscesses were not affected (P ≥ 0.23) by treatments. The digestibility of nutrients (P ≥ 0.13) and the ruminal VFA profile (P ≥ 0.12) were not affected by treatments. Steers offered MONPRO tended (P = 0.09) to have 16% greater average papillae number compared to other treatments. Yearlings offered finishing diets containing L. salivarius L28 plus monensin did not affect growth performance, digestibility, or ruminal VFA, but reduced feed intake. Carcass quality was negatively affected by treatments, while animals consuming L. salivarius L28 and monensin tended to improve ruminal morphology. Current findings in ruminal morphology and feed intake may warrant further assessment of diets containing L. salivarius L28 on beef cattle food safety aspects.

Production performance of Charolais crossbred steers fed total mixed ration containing a high level of dried cassava top

Objective: The objectives were to determine the appropriate level of dried cassava top (DCT) in total mixed ration (TMR) based on production performance and carcass characteristics of fattening Charolais crossbred steers. Materials and Methods: Fifteen fattening Charolais crossbred steers were randomly assigned to a randomized complete block design with initial body weight to receive three treatments, including without DCT, 15% DCT, and 30% DCT in TMR, on a dry matter (DM) basis. The production trial lasted 120 days; then, the fattened steers were slaughtered to study the carcass characteristics. Results: The in vitro gas production from the immediately soluble fraction of TMR containing 30% DCT was higher than the others (p &lt; 0.05). However, in vitro DM and organic matter degradability were not significantly different among treatments. Feed intake, final weight, feed cost per gain, and carcass characteristics such as warm carcass percentage, marbling score, and loin eye area of feedlot steers were not affected by the inclusion of DCT in TMR. Although steers fed TMR containing 15% DCT had body weight gain, average daily gain, and feed conversion ratio lower than the control (p &lt; 0.05); however, the use of DCT at 30% DM in TMR reduced the feed cost of feedlot beef production (p &lt; 0.05). Conclusion: Using local ingredients such as cassava tops can increase profit margins for farmers without sacrificing product quality, but they must closely look at growth performance.

Effectiveness of cottonseed cake fibre included in the diet of Nellore steers finished in confinement

ABSTRACT It was aimed to evaluate the use of cottonseed cake (CSC) as a source of physically effective neutral detergent fibre (peNDF) to replace corn silage (CS) in diet of feedlot-finished cattle. The design used was completely randomised, with 2 treatments (30% CSC and 30% CS) and 12 replications. There was interaction between fibre source and nutrient in the material retained in the Penn State Particle Separator. The highest concentrations (P = 0.0001) of peNDF and the in vitro digestibility of peNDF (DpeNDF) were for CSC. There was a higher (p < 0.05) dry matter intake (DMI) and neutral detergent fibre (NDF) intake (NDFI) by the animals on the CSC diet. The CSC-fed steers showed higher (P = 0.0001) final body weight (BW) and total weight gain. The steers fed CSC showed a longer (P = 0.0001) feeding time, feed efficiency, and lower rumination time (P = 0.0001) and rumination efficiency (P = 0.0001). There were positive correlations between the variables: rumination time × intake, rumination time × NDFI and peNDF × DpeNDF. It was observed that there was a negative correlation between the variables: rumination time × peNDF, rumination time × DpeNDF, NDFI × peNDF, and NDFI × DpeNDF. Cottonseed cake is an alternative source of peNDF for feedlot beef cattle.

Evaluating the effects of antimicrobial drug use on the ecology of antimicrobial resistance and microbial community structure in beef feedlot cattle.

Use of antimicrobial drugs (AMDs) in food producing animals has received increasing scrutiny because of concerns about antimicrobial resistance (AMR) that might affect consumers. Previously, investigations regarding AMR have focused largely on phenotypes of selected pathogens and indicator bacteria, such as Salmonella enterica or Escherichia coli. However, genes conferring AMR are known to be distributed and shared throughout microbial communities. The objectives of this study were to employ target-enriched metagenomic sequencing and 16S rRNA gene amplicon sequencing to investigate the effects of AMD use, in the context of other management and environmental factors, on the resistome and microbiome in beef feedlot cattle. This study leveraged samples collected during a previous longitudinal study of cattle at beef feedlots in Canada. This included fecal samples collected from randomly selected individual cattle, as well as composite-fecal samples from randomly selected pens of cattle. All AMD use was recorded and characterized across different drug classes using animal defined daily dose (ADD) metrics. Overall, fecal resistome composition was dominated by genes conferring resistance to tetracycline and macrolide-lincosamide-streptogramin (MLS) drug classes. The diversity of bacterial phyla was greater early in the feeding period and decreased over time in the feedlot. This decrease in diversity occurred concurrently as the microbiome represented in different individuals and different pens shifted toward a similar composition dominated by Proteobacteria and Firmicutes. Some antimicrobial drug exposures in individuals and groups were associated with explaining a statistically significant proportion of the variance in the resistome, but the amount of variance explained by these important factors was very small (<0.6% variance each), and smaller than associations with other factors measured in this study such as time and feedlot ID. Time in the feedlot was associated with greater changes in the resistome for both individual animals and composite pen-floor samples, although the proportion of the variance associated with this factor was small (2.4% and 1.2%, respectively). Results of this study are consistent with other investigations showing that, compared to other factors, AMD exposures did not have strong effects on antimicrobial resistance or the fecal microbial ecology of beef cattle.

Sustainable manure management systems in beef cattle feedlots

The population of feeder cattle in feedlots is not significant compared to the total cattle population. However, the intensive management system in feedlots has negative impact on the environment. Currently, there is limited information on manure handling in the beef cattle feedlots in Indonesia. This study aimed to describe the manure management system of surveyed feedlots in Lampung Province, Indonesia. The method of this study was descriptive with field observation and survey in three feedlots in Lampung. Data related to manure management were collected on the farm, while the data on manure management systems, animal characteristics, and housing system were gathered from questionnaires in the survey. The data were described and analysed using comparison with previous studies. The result showed that the surveyed feedlots utilize manure as organic fertilizer. The manure and effluent were treated and pumped onto forage fields. One feedlot company with an advanced manure treatment facility has implemented a sustainable manure management strategy. The study suggests further research to measure the carbon cycle for several types of feedlot’s manure management systems as an environmental product declares of beef cattle production in Indonesia.

Atmospheric deposition of particulate matter from beef cattle feedlots is a likely contributor of pyrethroid occurrence in isolated wetland sediment: Source apportionment and ecological risk assessment

Industrial cattle feeding operations (feedlots) have been subject to public scrutiny in recent decades regarding environmental impacts of site runoff and aerial dispersion of agrochemical-laden particulate matter (PM). However, source apportionment of multi-use pesticides is challenging in mixed agricultural settings. Beef cattle on feed and row crop production are heavily concentrated in the Southern Great Plains of North America, where playa wetlands are vulnerable to agrochemical inputs and sedimentation from surrounding land use. In the current study, playa basin sediment (n = 33) was analyzed via UHPLC-MS for 21 agrochemicals spanning eight classes (macrocyclic lactones, neonicotinoids, organophosphates, pyrethroids, triazoles, β-methoxyacrylates, a carboximide, and phenylpyrazole). Pyrethroids were detected most frequently (75.8% of basins). Sediment pyrethroid concentrations were also significantly correlated (R2 = 0.178, p = 0.007) with feedlot proximity (<1–50 km). Principal component analysis (PCA) of land use metrics extracted three principal components (74.3% of total variance), with principal component regression (PCR) showing the greatest agrochemical occurrence in basins heavily weighted by cropland buffer acreage (≤1 km) and feedlot proximity. Sediment toxicity benchmarks protective of two benthic invertebrates (Hyallela azteca and Chironomus spp.) identified λ-cyhalothrin, fenvalerate, and esfenvalerate as individual compounds exceeding levels of acute (RQ > 0.5) and chronic (RQ > 1) concern in >5% and >50% of cases, respectively. However, additive toxicity of co-occurring pyrethroids represents an acute high risk (RI > 1; median RI; acute = 2.4, chronic = 38.6) to benthic invertebrates in >75% of cases, which may threaten higher-order wetland taxa via bioaccumulation and trophic transfer.

Corrigendum to “Risk factors for mid- and late-feeding-stage bovine respiratory morbidity and mortality based on individual animal treatments of beef feedlot cattle” (Appl. Anim. Sci. 38:360–372)

Corrigendum to “Risk factors for mid- and late-feeding-stage bovine respiratory morbidity and mortality based on individual animal treatments of beef feedlot cattle” (Appl. Anim. Sci. 38:360–372)

Future of the beef feedlot industry

North American feedlot practice has evolved over the last four decades to become a highly specialized form of veterinary medicine offering integrated client solutions spanning from animal health protocols to data analysis and economic model­ing. Successful new and future feedlot practices will provide in­tegrated multidisciplinary solutions to clients while seeking to create opportunities for true producer-practitioner alignment. In its purest form, this will translate to co-investment and commitment of personal capital by veterinarians and produc­tion professionals who seek to monetize intellectual property through equity participation in the feedlot production systems they service.