Culture-Based Quantification with Molecular Characterization of Non-O157 and O157 Enterohemorrhagic Escherichia coli Isolates from Rectoanal Mucosal Swabs of Feedlot Cattle.

Enterohemorrhagic Escherichia coli (EHEC) strains are foodborne pathogens carried in the intestinal tracts of ruminants and shed in the feces. High concentrations (≥104 colony-forming units [CFU]/g) of EHEC in cattle feces are associated with contamination of hides, and subsequently, carcasses and beef. Several studies using agar media have quantified O157 but few have quantified non-O157 EHEC in samples from cattle. Thus, the objective of this study was to determine the concentration of O157 and non-O157 EHEC in cattle, and to characterize the associated EHEC isolates for their virulence potential. Two hundred feedlot steers were sampled by rectoanal mucosal swab (RAMS) every 35 days over four sampling periods, and a spiral plating method using modified Possé differential agar was used to quantify EHEC organisms in these samples. Bacterial colonies from agar plates were tested by multiplex PCR for Shiga toxin and intimin genes (stx and eae, respectively), and confirmed EHEC isolates (i.e., positive for both stx and eae) were serotyped and characterized for virulence genes using a microarray. Organisms detected in this study included O26, O101, O103, O109, O121, O145, O157, and O177 EHEC, with all except O121 quantifiable and measuring within a range from 9.0 × 102 to 3.0 × 105 CFU/g of RAMS sample. Organisms of the same EHEC serogroup were not detected in quantifiable concentrations from a single animal more than once. EHEC organisms most commonly detected at quantifiable levels were O26, O157, and O177. Interestingly, O26 EHEC isolates tested negative for stx1 but positive for stx2a. High concentrations of EHEC were detected in 11 (5.5%) of the steers at least once over the sampling period. These results indicate that in addition to O157, non-O157 EHEC are transiently present in high concentrations in the rectoanal mucosal region of cattle.

Technical note: assessing GPS sensor accuracy using real-time kinematic device for livestock tracking.

The technical aspects of global positioning system (GPS) sensors have been improved substantially over the years, making them valuable and popular tools for livestock tracking. Using GPS sensors allows producers and researchers to locate grazing livestock, monitor their behavior and distribution, and gather referencing information about the health status of the animals and pastures. However, interpreting the behavior of grazing livestock, such as cattle, from GPS data can be difficult due to positioning inaccuracies. Without knowing the positioning accuracy range of GPS sensors, achieving high-level confidence in determining grazing densities and identifying abnormal livestock movement patterns is challenging. In this study, the positioning accuracy of 3 different types of commercial GPS sensors was assessed using a survey-grade real-time kinematics (RTK) device. We outlined the procedures and essential equations and compared the recorded locations from the GPS sensors with reference locations collected from the RTK device. The results demonstrated statistically significant differences (P < 0.05) in positioning accuracy between different types of GPS sensors. The circular error probable (CEP) at 95% probability levels (CEP95) of the 3 sensors ranged from 2.46 to 11.06 m. This accuracy varied among individual sensors within the same brand and across different brands, which underscores the importance of evaluating the positioning accuracy of GPS sensors in livestock tracking. This study provides significant insights for animal scientists, ecologists, and livestock producers engaged in GPS sensor-related research and practices.

GPS sensors play a pivotal role in modern livestock tracking, enabling producers and researchers to monitor grazing livestock, understand their behavior, and assess health indicators. Despite their widespread use, effectively interpreting the gathered data poses challenges due to positioning inaccuracies. This technical note delves into the methodology of assessing the positioning accuracy of 3 commercial GPS sensor types using a survey-grade real-time kinematics device. Results reveal meter-level precision with variations in accuracy among individual sensors and brands. The study emphasizes the critical need to evaluate GPS sensor positioning accuracy in livestock tracking, offering valuable insights for animal scientists, ecologists, and livestock producers for enhanced research and practices using GPS sensors.

Effect of extended days on feed on carcass gain, efficiency, and quality of individually fed beef steers.

Crossbred steers (n = 114, initial BW = 334 kg; SEM = 5 kg) were serially harvested to evaluate the change in carcass composition by feeding cattle 21 or 42 d longer than the 2014 industry average subjective measure of finish, 1.27 cm of 12th rib fat thickness. Carcass ultrasound measurements were collected on 76 steers at 1, 78, and 134 days on feed (DOF) to project appropriate harvest date. Steers were sorted into three harvest groups, and serially harvested at 142, 163, or 185 DOF, with the first harvest date selected based on an estimated 12th rib fat thickness of 1.27 cm via ultrasound measurement. Steers were fed using an individual animal feeding system, to determine individual performance metrics. Steer DMI did not differ (P ≥ 0.31) between harvest groups, while carcass-adjusted ADG and G:F decreased linearly (P ≤ 0.04) as DOF increased. Carcass weight increased linearly (P < 0.01) as DOF increased from 142 to 185 DOF, with steers gaining an additional 36 kg of HCW when fed an additional 42 DOF. Carcass LM area quadratically increased (P = 0.04) to 163 DOF and remained constant to 185 DOF. Marbling score was not different (P = 0.14) between harvest groups; however, the opportunity to grade USDA Premium Choice was improved for steers fed to 185 DOF. Calculated YG and 12th rib fat thickness increased linearly (P < 0.01) as DOF increased, with distributions across YG 1 through 5 differing between harvest groups (P < 0.01), and 185-d carcasses having the greatest frequency of YG 4 carcasses. As cattle are fed for additional DOF, live ADG and G:F decline, while HCW and LM area increase.

Effect of corn silage inclusion with different corn processing on finishing steer performance and carcass characteristics.

Objectives were to determine the effect of corn silage inclusion within dry-rolled corn (DRC) or steam-flaked corn (SFC) finishing diets on cattle growth performance and carcass characteristics. The experiment used British and continental crossbred steers (n = 480; initial body weight [BW] = 389 ±â€…17 kg) in a 4 × 2 factorial arrangement of treatments with six replications per treatment. Treatments consist of four inclusions of corn silage (0%, 15%, 30%, or 45%; dry matter [DM] basis) within either a DRC or SFC diet. A corn silage by corn processing interaction was observed for dry-matter intake (DMI; P = 0.05). As corn silage inclusion increased in the diet, DMI increased linearly (P < 0.01) for both corn processing methods. DM intake was not different between SFC and DRC-fed cattle at 0% (P = 0.33), 30% (P = 0.90), or 45% (P = 0.31) corn silage inclusion. The interaction was due to the DMI of cattle fed 15% silage, as cattle-fed DRC consumed 0.5 kg/d less (P < 0.01) than cattle on the SFC diet. Quadratic effects were observed for final BW, hot carcass weight (HCW), average daily gain (ADG), feed efficiency (G:F), marbling, and fat depth (P < 0.01), regardless of corn processing. Cattle fed 15% or 30% corn silage gained faster (P < 0.01) than those fed 0% or 45% corn silage. Feed efficiency decreased quadratically (P < 0.01) as silage inclusion increased in the diet with G:F similar for cattle fed 0% and 15% silage and decreased curvilinearly for cattle fed 30% and 45% silage. The incidence of liver abscesses was greater (P = 0.03) in cattle fed 0% corn silage than for steers fed 15%, 30%, or 45% corn silage. Corn processing method, independent of silage, had no effect (P = 0.42) on liver abscess incidence. Feeding SFC increased (P < 0.01) steer final BW and HCW when compared to cattle-fed DRC, regardless of silage inclusion. Corn silage inclusion had similar effects on performance in both DRC diets and SFC diets except for DMI. As corn silage inclusion increased in the diet, feed efficiency decreased linearly (P < 0.01). Cattle-fed SFC gained 7.9% more (P < 0.01) and were 6.7% more efficient (P < 0.01) than cattle-fed DRC. In diets containing either DRC or SFC, corn silage can be included at up to 30% of the diet without negative impacts on ADG or HCW.

Effect of an algae feed additive on reducing enteric methane emissions from cattle.

Alga 1.0, a product containing bromoform, was fed to cattle to evaluate its effects on methane (CH 4 ) and carbon dioxide (CO 2 ) emissions and diet digestibility. Twelve nonlactating, nonpregnant Jersey cows (490 ±â€…19 kg body weight) were used in four replicated 3 × 3 Latin squares with three periods, each consisting of 21 d. Cows were blocked by feed intake (averaged intakes over 4 wk prior to trial) and assigned randomly to one of three treatments. Treatments included Alga 1.0 fed at 0, 69, and 103 g/d in a 0.454 kg/d dry matter (DM) top-dress daily in a modified distillers grains plus solubles (MDGS) carrier. Diet consisted of 60% dry-rolled corn, 20% corn silage, 15% modified distillers grains, and 5% supplement (DM basis). Headbox-style indirect calorimeters were utilized to evaluate gas production from individual cows with two nonconsecutive 23-h collections in each period. Data were analyzed using the GLIMMIX procedure of SAS with cow within square as experimental unit and as a random effect, and treatment and period as fixed effects. Linear and quadratic contrasts were used to compare treatments. Feeding Alga 1.0 linearly reduced dry matter intake (DMI, P < 0.01) by 10.1% for 69 g/d inclusion and 13.3% for 103 g/d inclusion compared to the control. Nutrient intakes decreased linearly (P < 0.01) due to lower DMI, but nutrient digestibility was not impacted (P ≥ 0.28). Inclusion of Alga 1.0 did not impact gross energy or digestible energy concentration of the diets expressed as Mcal/kg DM (P ≥ 0.22) but did linearly reduce energy intake (Mcal/d; P < 0.01). Feeding Alga 1.0 linearly reduced enteric CH4 emissions measured as g/kg DMI (P < 0.01) by 39 and 64% for 69 g/d and 103 g/d inclusion, respectively. Linear reductions (P < 0.01) of 64% to 65% were also observed in enteric CH4 emissions when expressed per kilogram of DM or organic matter digested. Respired CO2 as g/d linearly decreased (P = 0.03) for cattle fed Alga 1.0 but did not differ when expressed as g/kg of DMI (P ≥ 0.23). Oxygen consumption did not differ between treatments for g/d and g/kg DMI (P ≥ 0.19). In conclusion, feeding Alga 1.0 reduced DMI up to 13.3%, did not impact digestibility, and significantly reduced CH4 emissions up to 63%.

Impact of Partial Oil Removal on Energy Content of Distillers Grains Plus Solubles for Finishing Cattle.

Two experiments evaluated the impact of the reduction in the percentage of corn oil remaining in distillers grains plus solubles (DGS) after the ethanol plant de-oiling process or by adding corn oil back to DGS following de-oiling on finishing cattle performance and nutrient digestion. Experiment 1 utilized 320 yearling steers (initial BW = 413 kg; SD = 25 kg) fed in 32 pens (10 steers/pen) and assigned to one of four treatments (n = 8 pens/treatment). The four treatments consisted of a blended DRC:HMC corn control diet (CON), de-oiled modified distillers grains plus solubles included at 40% of diet DM (DODGS), de-oiled modified distillers grains plus solubles included at 38% of diet DM plus 2% added corn oil (DODGS + Oil), and full-fat modified distillers grains plus solubles included at 40% of diet DM (FFDGS). The DODGS product contained 8.9% fat while the FFDGS product contained 11.6% fat. Dry matter intake (DMI) was impacted by treatment (p = 0.01) with steers fed DODGS having the greatest DMI and steers fed CON, DODGS + Oil, and FFDGS having lower DMI. Dietary treatment tended to impact ADG (p = 0.06) with steers fed DODGS and DODGS + Oil having greater gains than CON, with FFDGS being an intermediate. As a result of increased ADG, G:F differed between treatments (p < 0.01) with the greatest feed efficiency observed for steers fed DODGS + Oil and FFDGS. Including MDGS in the diet improved G:F by 6 to 11% compared to feeding DRC:HMC corn blend, with an improvement in G:F of 4.9 and 1.2% for DODGS + Oil and FFDGS, respectively, compared to DODGS. Hot carcass weight was impacted by dietary treatment (HCW; p = 0.05), with DODGS- and DODGS + Oil-fed steers having the heaviest HCW, CON steers having the lightest HCW, and FFDGS being an intermediate. Experiment 2 was a 5 × 4 unbalanced Latin rectangle digestion experiment with four diets, five ruminally cannulated steers, and five periods that utilized the same treatments as Exp. 1. Dietary fat measured 4.2, 6.0, 7.9, and 7.1% for CON, DODGS, DODGS + Oil, and FFDGS, respectively. Intakes of DM, OM, and energy as well as total tract fat digestibility and DE (Mcal/d) were not impacted by dietary treatment (p ≥ 0.46). When corn oil was added back to de-oiled MDGS, there was a negative impact on digestibility of OM (p < 0.01) and NDF (p = 0.07) compared with DODGS, FFDGS, and CON. Partially removing oil from modified distillers grains plus solubles did not significantly impact cattle performance, carcass traits, energy content, or digestibility when MDGS was included at approximately 40% of diet DM.

Interaction of Sweet Bran inclusion and corn processing method in beef finishing diets.

The study objective was to determine the effects of corn processing method and Sweet Bran (Cargill, Blair, NE) inclusion in beef finishing diets on performance and carcass characteristics. Four hundred and eighty crossbred yearling steers (363 ±â€…15 kg) were assigned to a 2 × 3 factorial arrangement of treatments, consisting of two corn processing methods, steam-flaked corn (SFC) or a high-moisture corn: dry-rolled corn blend (HMC: DRC), and three inclusions of Sweet Bran (0%, 20%, or 40% of diet dry matter). Data were analyzed using the MIXED procedure of SAS as a generalized block design with pen as the experimental unit and block as a fixed effect. Dry matter intake increased linearly as Sweet Bran increased in the diet, regardless of corn processing method (P < 0.01). A corn processing × Sweet Bran interaction (P < 0.01) was observed for feed efficiency (G:F), average daily gain (ADG), and hot carcass weight (HCW). The G:F of steers fed SFC did not change with increasing Sweet Bran concentrations (P = 0.19) and the G:F of SFC-fed steers was 12.4% greater than those fed HMC:DRC without Sweet Bran, but was only 5.3% greater when Sweet Bran was included at 40% (P = 0.04). The ADG of steers increased linearly with increasing concentration of Sweet Bran in both SFC and HMC:DRC-based diets. However, the interaction occurred (P < 0.01) because ADG increased at a greater rate in HMC:DRC-based diets (1.93 to 2.21 kg/d for 0% and 40% Sweet Bran, respectively) compared to SFC-based diets (2.18 to 2.27 kg/d for 0% and 40% Sweet Bran, respectively;). Accordingly, while the ADG of steers fed SFC was 13% greater than steers fed HMC:DRC without Sweet Bran (P < 0.01), there was no difference in ADG due to corn processing method at 40% Sweet Bran (P = 0.30). In SFC-based diets, HCW tended to increase from 446 to 455 kg as Sweet Bran increased (P = 0.06). In HMC: DRC-based diets, HCW linearly increased from 421 to 449 kg (P < 0.01), resulting in similar HCW at 40% Sweet Bran (P = 0.28). These data suggest HMC:DRC-based diets are more competitive with SFC-based diets due to similar gains and more similar feed efficiencies when Sweet Bran is fed.

Assessment of heterogeneity of efficacy of a three-dose regimen of a type III secreted protein vaccine for reducing STEC O157 in feces of feedlot cattle.

Preharvest control of Escherichia coli O157:H7 (STEC O157) may prevent human illness by reducing the presence of STEC O157 throughout the beef production chain. Immunization of cattle with a type III secreted protein vaccine inhibits colonization of cattle with STEC O157 and reduces the probability of fecal shedding and hide contamination. Our objectives were to perform a meta-analysis to estimate efficacy of a three-dose regimen of TTSP vaccine at reducing the presence of STEC O157 in the feces of feedlot cattle and to test factors that might modify vaccine efficacy. Pen-level data (n=184 pens, 1462 cattle) from four randomized controlled vaccine trials conducted from 2002 to 2008 at the University of Nebraska-Lincoln were analyzed. Factors explaining a culture-positive fecal sample were tested in generalized estimating equations logistic regression and log-binomial models. An autoregressive correlation structure was defined to account for clustering of repeated test-periods within block. Clustering or potential confounding by study was accounted for by treating study as a fixed effect. STEC O157 was detected from 661 of 5451 postvaccination fecal samples. The probability to detect STEC O157 postvaccination was 8.4% and 15.8% in vaccinated and unvaccinated cattle, respectively. Interactions between vaccination and (1) study; (2) prevalence of control pens within each time-place cluster; and (3) days from vaccination were not significant or fit poorly with observed data. Adjusting for study, cattle in pens receiving three doses of vaccine were less likely to shed STEC O157 (odds ratio=0.46, p<0.0001). Model-adjusted vaccine efficacy was 48% (95% confidence interval: 0.37-0.57). We concluded that a three-dose regimen type III secreted protein vaccine was efficacious at reducing the probability of detecting STEC O157 in the feces of cattle and that vaccine efficacy was not modified by study or level of prevalence observed in control pens.

Pooled analysis on the effects of inclusion, moisture, and oil removal from distillers grains on cattle performance and economic returns in diets with different corn processing.

A synthesis of data including over 9,300 head of cattle and over 980 pen means was conducted to evaluate the effect of corn processing method, distillers grains type, oil removal from distillers, and dietary distillers concentration on cattle performance and total feeding costs under different historical price scenarios. The corn processing method was either steam-flaked corn, high-moisture or dry-rolled corn or a blend of the latter two and their effects on performance with and without distillers grains. Wet, modified, and dry distillers were analyzed as either full fat or de-oiled products in diets at various dietary concentrations with either corn type to determine cattle performance. Performance estimates were used to determine the inclusion level that minimized total finishing costs ($/head) for each diet given various assumptions on corn price, corn-to-distillers price ratio, supplemental protein cost, and steam flake processing cost. Feeding distillers grains in steam-flaked or high-moisture and dry-rolled corn diets resulted in improved feed conversion and reduced cattle feeding costs, including lower supplemental protein costs and lower total feeding costs compared with a diet without distillers. However, feeding diets with steam-flaked corn improved feed conversion regardless of distillers type or level of inclusion. Feeding full fat distillers improved feed conversion relative to de-oiled distillers. Cattle fed de-oiled distillers were more efficient than those fed diets containing no distillers grains. At all corn price and corn-to-distillers price ratios examined, feeding some level of distillers of any type produced a lower total feeding costs relative to a diet without distillers. Different robustness tests were conducted to determine the impact of varying steam flake corn processing costs and the cost of supplemental protein on the optimal level of distillers inclusion level. The break-even cost a producer could pay for steam-flaking corn varied but was significantly higher when corn price was high. Feeding distillers grains in steam-flaked or high-moisture and dry-rolled corn diets resulted in improved feed efficiency, reduced cattle feeding costs, including replacement of other supplemental protein and associated costs compared to a diet without distillers grains.

A pooled analysis of research was conducted to evaluate the effect of corn processing method, distillers grains type, oil removal from distillers, and distillers inclusion on cattle performance within studies conducted at the University of Nebraska-Lincoln between 1992-2020. Two corn processing methods were included in the dataset, steam-flaked corn (SFC) or any combination of high-moisture (HMC) and dry-rolled corn (DRC), fed with and without distillers gains, a by-product of the dry milling ethanol industry. Distillers products were either wet, modified, or dry distillers grains plus solubles and were analyzed as both full fat and de-oiled products. Cattle performance resulting from feeding the six by-product combinations with both corn types was analyzed and then used to find the inclusion level that minimized the total feeding cost ($/head) given different corn prices and corn-to-distillers price ratios. Cattle had improved feed conversion when fed SFC compared with HMC:DRC in all diets. Cattle fed full-fat distillers grains had slightly improved feed conversions compared with de-oiled distillers grains. Cattle fed distillers grains diets had improved feed conversion compared with cattle fed control diets without distillers. Overall, feeding distillers grains in combination with either corn type offers benefits including improved feed conversions, lower finishing costs, and reduced reliance on supplemental protein sources compared to a diet without distillers.

Evaluation of growth performance, carcass characteristics, and methane and CO2 emissions of growing and finishing cattle raised in extensive or partial-intensive cow-calf production systems.

An experiment was conducted over 2 yr to measure performance and greenhouse gas (GHG) emissions of weaned calves from two cow-calf production systems. Crossbred steers and heifers (n = 270, initial body weight (BW) = 207 kg, SD = 35) were used in a randomized complete block design, with treatments applied to the cow-calf system. Treatments were: 1) a traditional system consisting of April to June calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to September calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). Calves from both production systems were weaned at the same age and grown (diet NEg = 1.05 Mcal kg-1) for approximately 117 d. The calves then transitioned to a high-grain finishing diet (year 1: NEg = 1.32 Mcal kg-1; year 2: NEg = 1.39 Mcal kg-1) and fed to a targeted 1.52 cm backfat. Growth performance in the grower phase resulted in greater (P < 0.01) average daily gain (1.39 vs. 1.22 ± 0.02 kg), greater gain:feed (P < 0.01; 0.157 vs. 0.137 ± 0.003) for ALT calves compared to TRAD calves, However, a lower initial BW (P < 0.01; 185 vs. 229 ± 4.9 kg) resulted in a lower ending BW (P < 0.01; 347 vs. 371 ± 2.9 kg) for ALT calves compared to TRAD calves in spite of improved growth performance. In the finisher phase, ALT calves gained less (1.52 vs. 1.81 ± 0.218 kg; P = 0.02), were less efficient (0.139 vs. 173 ± 0.0151; P = 0.01) but exhibited similar hot carcass weights (HCW) (388 vs. 381 ± 3.8 kg; P = 0.14) compared to TRAD calves. Each pen of calves was put into a large pen-scale chamber that continuously measured carbon dioxide (CO2) and methane (CH4) for 5 d during the grower and finisher phases. The average CH4 and CO2 production per unit of feed intake was used to calculate total GHG emissions over the entire grower and finisher phase. Overall, there were no differences (P ≥ 0.17) between treatments for CH4 per day and per kilogram dry matter intake (DMI). However, ALT calves tended to produce less (P ≤ 0.10) CO2 per day and per kilogram DMI than TRAD calves. Overall, methane emissions were greater in ALT calves (110.7 vs. 92.2 ± 8.3 g CH4 kg-1 HCW; P = 0.04) than TRAD calves. The ALT calves required 27 additional days on feed to market, which resulted in more total CH4 per animal across the entire feeding period (P = 0.02) than TRAD calves. Production systems that reduce days to market to achieve similar HCW may reduce GHG emissions.

There are many reasons (i.e. drought, limited perennial forage, calving) for using intensive or partially intensive production practices (e.g. drylotting or confinement) in a cow-calf enterprise. These practices may impact subsequent calf growth and feedlot performance. In addition, limited data are available comparing the environmental impacts (i.e., greenhouse gas (GHG) emissions) from different cow-calf production systems. This experiment evaluated the effects of a partial-intensive cow-calf production system on post-weaning calf growth performance, carcass characteristics, and GHG emissions. Calves from the partial-intensive cow-calf system had improved growth compared to calves from the extensive cow-calf system during the grower phase. During finishing, calves from the partial-intensive cow-calf system had poorer growth performance resulting in calves from the partial-intensive cow-calf system requiring an additional 27 d on feed to reach finish as calves from the traditional cow-calf system. These differences are likely due to compensation from lower gain periods resulting in better gain in the subsequent growth period. Cow-calf production system did not alter methane and carbon dioxide emissions per kilogram of intake. However, because calves in the partial-intensive cow-calf system required additional days on feed, absolute methane and carbon dioxide emissions were greater per animal for the partial-intensive cow-calf system compared to the extensive cow-calf system suggesting that reducing days to market may reduce emissions from beef systems.

Effect of increasing corn silage inclusion in finishing diets cattle with or without tylosin on performance and liver abscesses.

A pooled analysis was performed to evaluate whether corn silage fed at 15% or 45% of diet DM impacted liver abscesses prevalence at slaughter in five previous experiments. Cattle fed 15% corn silage had 7.8% abscessed livers compared to 4.1% for cattle fed 45% corn silage when all diets contained tylosin. While improved due to increased corn silage inclusion, the objective of the current finishing study was to determine the impact of silage inclusion in finishing diets with and without tylosin on performance and incidence of abscessed livers in beef cattle. A total of 640 (BW = 334 ± 25 kg) steers were used in a generalized randomized block design with a 2 × 2 factorial treatment design. Treatments included two concentrations of corn silage (15% and 45% of diet DM), with or without tylosin for liver abscesses. This study used 32 pens of cattle with 20 steers per pen and 8 pens per treatment. There was a tendency for an interaction for feed efficiency (G:F; P = 0.10) where cattle fed 15% corn silage had a 2% increase in G:F when tylosin was added to the diet, but no improvements in G:F were observed when tylosin was added to diets containing 45% silage. There was an interaction between silage and tylosin inclusion for abscessed livers (P = 0.05). Cattle fed 15% corn silage without tylosin had the greatest incidence of abscessed livers (34.5%) compared to other treatments (P = 0.05), and the incidence of abscessed livers was decreased to 19% if tylosin was fed with 15% corn silage. Feeding 45% silage was effective at lowering the incidence of abscessed livers (P = 0.05) which was 12.4%, regardless of whether tylosin was fed. Feeding corn silage at 45% of diet DM (77.5% concentrate) was as effective as feeding tylosin to cattle on a 92.5% concentrate diet. Feeding corn silage at greater inclusions decreased daily gain (P ≤ 0.01) but increased final body weight when fed to an equal fatness (cattle fed 45% CS were fed 28 d longer). Feeding corn silage at 45% was more economical compared to feeding 15% corn silage, especially as corn prices increase, provided shrink is well managed. Feeding elevated concentrations of corn silage may be an economically viable method to reduce incidence of liver abscesses without antibiotic use for smaller operations that can manage more corn silage in finishing diets.

Antibiotics are a very effective method to control liver abscesses for finishing cattle, which are thought to be due to high starch concentration and acidosis. Dietary roughage (forage) is used to control acidosis. As grain prices increase, feeding greater amounts of corn silage may be advantageous and silage can be an economical forage compared to other traditional forages like alfalfa. This study evaluated the impact of corn silage inclusion on performance and abscessed livers with and without the addition of antibiotics. As expected, feeding more corn silage decreased both gain and feed efficiency but also increased profitability. Feeding tylosin with a traditional inclusion of silage (15%) decreased abscessed livers from 34.5% to 19%. However, if cattle are fed more silage (45%) the incidence of abscessed livers was 12.4%, regardless of feeding tylosin or not.

Impact of shade in beef feedyards on performance, ear temperature, and heat stress measures.

A 2-yr study (year 1: March to September 2017; year 2: February to August 2018) was conducted using crossbred steers (year 1: n = 1677; initial body weight [BW] = 372 kg, SD = 47; year 2: n = 1713; initial BW = 379 kg, SD = 10) in a commercial feedyard study in Eastern NE to determine the effects of shade on cattle performance, ear temperature, and cattle activity. Two treatments were evaluated using a randomized complete block design (n = 5 blocks based on arrival). Treatments were assigned randomly to pens and consisted of five pens without shade (NO SHADE) and five pens with shade (SHADE). Ear temperatures were collected throughout the trials using biometric sensing ear tags on a subset of cattle. Panting scores were collected using a 5 point scale determined visually based on the level of panting occurring on the same subset of steers a minimum of twice weekly from June 8 to August 21 in year 1 and May 29 to July 24 in year 2 by one trained individual each year. In year 1, no differences (P ≥ 0.24) were observed for growth performance or carcass characteristics. Dry matter intake (DMI) and average daily gain (ADG) were greater (P ≤ 0.04) for SHADE cattle in year 2. Over the entire feeding period in year 1, greater (P < 0.01) ear temperature was observed for NO SHADE cattle, but cattle movement was not different (P = 0.38) between treatments. When evaluating the entire feeding period in year 2, cattle movement and ear temperature were not different (P ≥ 0.80) between treatments. Cattle in the SHADE treatment had lower (P ≤ 0.04) panting scores in years 1 and 2. These data suggest that providing shade can lessen the negative influence of heat events on DMI and was an effective way to reduce heat stress in feedlot operations, but only impacted ADG if heat events were close to the cattle slaughter date.

This study was performed over two separate summers to evaluate natural exposure to heat and quantify the impact that providing shade has on stress measures, estimates of body temperature, and feedlot performance. In the first year, cattle were marketed after summer heat events and while ear temperature and panting scores were decreased for cattle in shaded pens, the effect was not significant enough to influence performance parameters. In the second year when cattle were marketed more immediately following heat impacts, cattle fed in shaded pens consumed more feed and gained more weight than cattle fed in pens without shade. In both years, cattle decreased dry matter intakes to offset normal heat events.

Impact of different corn milling methods for high-moisture and dry corn on finishing cattle performance, carcass characteristics, and nutrient digestion.

Two experiments were conducted to evaluate the effect of different corn milling methods for high-moisture and dry corn on finishing cattle performance, carcass traits, and nutrient digestion. In experiment 1, steers (N = 600 [60 pens]; initial body weight [BW] = 402 ± 17 kg) were fed for 134 d to evaluate the effect of milling method and corn type on performance and carcass characteristics. Treatments were evaluated as a 2 × 3 factorial design with factors being milling method (Automatic Ag roller mill [ROLL] or hammer mill [HAMMER]) and corn type (high-moisture [HMC], dry [DC], or 50:50 blend of HMC and DC [BLEND]). There were no milling method × corn type interactions for final BW, gain (ADG), or dry matter intake (DMI; P ≥ 0.32), but there tended to be an interaction for G:F (P = 0.09). Cattle fed ROLL HMC had 4.7% greater gain:feed (G:F; P ≤ 0.01) with 55% lower fecal starch (P < 0.01) compared to HAMMER HMC, whereas processing did not impact (P = 0.74) G:F in DC diets. There were no further effects (P ≥ 0.14) on performance or carcass traits regardless of milling method or corn type. In experiment 2, seven ruminally fistulated steers were utilized in a 4 × 7 incomplete Latin rectangle to evaluate the effects of DC or HMC processed with either ROLL or HAMMER (2 × 2 factorial treatment design) on nutrient digestion. Feeding HMC decreased the amount of excreted dry matter (DM) and organic matter (OM; P ≤ 0.01) regardless of mill type, but there was a tendency (P ≤ 0.13) for an interaction between corn type and mill type for DM and OM digestibility. There was no difference between milling treatments fed as HMC (P ≥ 0.69), but the HAMMER DC diet was more digestible than the ROLL DC (P = 0.05). As expected, HMC-based diets had greater (P < 0.01) starch digestibility compared to DC, but milling method had no impact on starch digestibility (P = 0.56). There were no differences (P = 0.56) in average ruminal pH, but HMC diets had greater variance (P = 0.04) and greater area less than pH 5.6 (P = 0.05) compared to DC based diets while milling method did not impact either (P > 0.33). Processing HMC with a roller mill improved G:F compared to processing with a hammer mill, but had little effect when corn was fed as dry corn or HMC:DC blend. Furthermore, feeding cattle HMC compared to DC increases nutrient digestibility, but milling method had little impact.

Two experiments tested how processing of corn grain for finishing cattle influences growth performance and nutrient digestion. Producers can use corn in dry or high-moisture form but normally use either a hammer mill or roller mill. When using high-moisture corn, we observed a 5% improvement in gain:feed (G:F) for rolling as compared to hammer milling, which is likely due to more uniform particle size and improved digestion. Unlike the performance study, milling method did not impact digestion for high-moisture corn. Using a hammer-mill for dry corn improved digestion compared to rolling which was not supported by improved performance in the finishing study. Using high-moisture corn increases risk of ruminal acidosis compared to dry corn, but also improves feed efficiency if acidosis can be minimized.

Mineral composition of serially slaughtered Holstein steers supplemented with zilpaterol hydrochloride.

Calf-fed Holstein steers (n = 115; 449 ± 20 kg) were utilized in a serial harvest experiment. A baseline group of five steers was harvested after 226 d on feed (DOF), which was designated day 0. The remaining cattle were assigned randomly to 11 harvest groups, with slaughter every 28 d. Cattle were either not (CON) or were fed zilpaterol hydrochloride for 20 d followed by a 3 d withdrawal (ZH). There were five steers per treatment in each slaughter group ranging from days 28 to 308. Whole carcasses were divided into lean, bone, internal cavity, hide, and fat trim components. Apparent mineral retention (Ca, P, Mg, K, and S) within the body was calculated as the difference between mineral concentration at slaughter and day 0. Mineral concentration at day 0 was determined from body composition of steers harvested at day 0 multiplied by individual live body weight (BW) at day 0. All data were analyzed as a 2 × 11 factorial arrangement with individual animal as the experimental unit. Orthogonal contrasts were used to analyze linear and quadratic contrasts over time (11 slaughter dates). There were no differences in concentration of Ca, P, and Mg in bone tissue as feeding duration increased (P ≥ 0.89); concentration of K, Mg, and S in lean tissue did fluctuate across DOF (P < 0.01). Averaged across treatment and DOF, 99% of Ca, 92% of P, 78% of Mg, and 23% of S present in the body were in bone tissue; 67% of K and 49% of S were in lean tissue. Expressed as gram per day, apparent retention of all minerals decreased linearly across DOF (P < 0.01). Expressed relative to empty body weight (EBW) gain, apparent Ca, P, and K retention decreased linearly as BW increased (P < 0.01) whereas Mg and S increased linearly (P < 0.01). Apparent retention of Ca was greater for CON cattle (greater bone fraction) and apparent retention of K was greater for ZH cattle (greater muscle fraction) when expressed relative to EBW gain (P ≤ 0.02), demonstrating the increase in lean gain by ZH cattle. There were no differences in apparent retention of Ca, P, Mg, K, or S due to treatment (P ≥ 0.14) or time (P ≥ 0.11) when expressed relative to protein gain. Apparent retention averaged 14.4 g Ca, 7.5 g P, 0.45 g Mg, 1.3 g K, and 1.0 g S/100 g protein gain. Expressing apparent mineral retention on a protein gain basis minimized effects of rate and type of gain, allowing for better comparison across treatments and time. Feeding zilpaterol hydrochloride did not affect apparent mineral retention when expressed relative to protein gain.

Mineral requirements for feedlot cattle are largely based on measured mineral concentration in the body at harvest. Fairly extensive research has been done quantifying Ca and P in the body of cattle, but data on Mg, K, and S are sparse. Serial harvest experiments are expensive and labor intensive and therefore not conducted frequently. A group of 115 Holstein steers was fed a finishing diet with serial harvest every 28 d. Two treatments were evaluated, control and cattle fed zilpaterol hydrochloride to increase lean tissue growth. Every 28 d, five steers from each treatment group were harvested with the whole carcass divided into lean, bone, internal cavity, hide, and fat trim components. Apparent mineral retention was calculated as the difference between mineral composition at day 0 (baseline harvest group) and each 28 d harvest group. Averaged across treatment and days on feed, 99% of Ca, 92% of P, 78% of Mg, and 23% of S present in the body were measured in bone tissue; 67% of K and 49% of S were in lean tissue. Apparent retention averaged 14.4 g Ca, 7.5 g P, 0.45 g Mg, 1.3 g K, and 1.0 g S/100 g protein gain.

Individual Beef Cattle Identification Using Muzzle Images and Deep Learning Techniques.

Individual feedlot beef cattle identification represents a critical component in cattle traceability in the supply food chain. It also provides insights into tracking disease trajectories, ascertaining ownership, and managing cattle production and distribution. Animal biometric solutions, e.g., identifying cattle muzzle patterns (unique features comparable to human fingerprints), may offer noninvasive and unique methods for cattle identification and tracking, but need validation with advancement in machine learning modeling. The objectives of this research were to (1) collect and publish a high-quality dataset for beef cattle muzzle images, and (2) evaluate and benchmark the performance of recognizing individual beef cattle with a variety of deep learning models. A total of 4923 muzzle images for 268 US feedlot finishing cattle (>12 images per animal on average) were taken with a mirrorless digital camera and processed to form the dataset. A total of 59 deep learning image classification models were comparatively evaluated for identifying individual cattle. The best accuracy for identifying the 268 cattle was 98.7%, and the fastest processing speed was 28.3 ms/image. Weighted cross-entropy loss function and data augmentation can increase the identification accuracy of individual cattle with fewer muzzle images for model development. In conclusion, this study demonstrates the great potential of deep learning applications for individual cattle identification and is favorable for precision livestock management. Scholars are encouraged to utilize the published dataset to develop better models tailored for the beef cattle industry.

Evaluation of the effects of wood-sourced biochar as a feedlot pen surface amendment on manure nutrient capture.

Feedstuffs utilized in U.S. feedlot finishing rations incorporate high concentrations of N and P, with less than 15% of fed N and P retained by the animal. The remaining N and P are excreted in the manure, where the opportunity for manure N loss via ammonia (NH3) volatilization from the feedlot pen surface is a risk to the environment and lowers the value of manure as a fertilizer. Two nutrient mass balance experiments were conducted during the winter and summer seasons to evaluate the effects of spreading unprocessed Eastern red cedar biochar onto the feedlot pen surface on manure nutrient capture and cattle performance. A 186-d feedlot finishing experiment was conducted from December to June (WINTER) and a subsequent 153-d finishing experiment was conducted from June to November (SUMMER). The WINTER experiment evaluated three treatments (5 pens per treatment; 10 steers per pen), including biochar spread on pen surface during the feeding period (1.40 kg biochar/m2; 17.6 m2/steer soil surface of the pen), hydrated lime spread on pen surface at end of feeding period (1.75 kg/m2) and control (no treatment applied). The SUMMER experiment evaluated biochar treatment (1.40 kg biochar/m2; 5 pens per treatment; 8 steers per pen; and 22 m2/steer soil surface of the pen) against control. There were no differences in N and P intake, retention, or excretion (P ≥ 0.38) between WINTER treatments. Steer performance (P ≥ 0.10) and carcass characteristics (P ≥ 0.50) were not impacted by pen treatment in WINTER. Nitrogen and P intake and excretion (P ≥ 0.35) were not different between treatments in SUMMER and retention of N and P was significantly greater for the biochar treatment (P ≤0.04) due to greater ADG (P = 0.05). There was no difference in DMI (P = 0.48) in SUMMER, steers on biochar pen treatment had heavier HCW (P = 0.05) and greater ADG, resulting in a tendency for greater feed efficiency (P = 0.08). In both experiments, biochar addition to the pen surface tended (P = 0.07) to increase manure N as a percent of manure DM, but this increase in N concentration did not impact kg of N removed from the feedlot pens (P ≥ 0.15) or N losses (P ≥ 0.68). The addition of red cedar biochar to the feedlot pen surface did not increase manure nutrient capture of N or P and did not reduce N losses associated with soil-based feedlot pens.

Production cow-calf responses from perennial forage-based and integrated beef-cropping systems.

An experiment was conducted to measure production responses of an alternative cow-calf production system integrated into a cropping system without access to perennial forage compared to a traditional cow-calf system utilizing perennial forage. Multiparous, cross-bred beef cows (n = 160; average age = 6.2 ± 2.8 yr) were utilized in a randomized complete block experimental design and unstructured treatment design. Upon initiation, cows were blocked by age and stratified by source, assigned randomly to one of two production systems, each with four replicates (n = 20 cows/replicate). Once allotted to their treatment groups, cows remained in their experimental units for the duration of the experiment. Treatments were: 1) a traditional system consisting of April to May calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to August calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). There were no differences (P ≥ 0.27) in calving rates (91.8 vs. 86.7 ± 2.92%), pregnancy rates (89.3 vs. 89.9 ± 2.66%), and weaning rates (87.2 vs. 82.3 ± 3.29%) for TRAD vs. ALT, respectively. However, there was an increase (P = 0.04) in the rate of twin offspring in ALT (2.9 vs. 9.4 ± 2.36% for TRAD vs. ALT, respectively). One calf from the set of twins was selected randomly at birth to be removed from the experiment, so the production data are only from single calves. There was no difference (P = 0.47) in calf body weight at birth (40 vs. 39 ± 0.7 kg for TRAD vs. ALT, respectively). At weaning, calves in the ALT system were lighter (P < 0.01) at the same day of age (184 vs. 229 ± 5.5 kg) compared to TRAD calves. Cows from the ALT system had fewer (P < 0.01) kg weaned per cow exposed to bull (150 vs. 199 ± 7.2 kg) compared to TRAD cows. Apart from the twinning rate, no differences in reproductive performance were observed among systems. However, reduced weaning weights and kilogram of weaned calf per cow exposed may negatively impact revenue to the cow-calf enterprise of the ALT system.

The effect of corn silage hybrid and inclusion on performance of finishing steers and silage hybrid effects on digestibility and performance of growing steers.

Three experiments evaluated the effects of three corn silage hybrids, inclusion, and nutrient digestibility in growing and finishing diets. The three hybrids tested included a control (CON), a hybrid containing a brown midrib (bm3) trait (BM3), and an experimental bm3 hybrid with the soft endosperm trait (BM3-SOFT). Experiment 1 utilized 360 crossbred steers (body weight [BW] = 334; SD = 25 kg) to evaluate inclusion of silage in a finishing diet at (15% or 45% of diet dry matter [DM]) and silage hybrid (CON, BM3, or BM3-SOFT). Experiment 2 and 3 utilized 216 crossbred steers (BW = 324; SD = 10 kg) and six ruminally fistulated steers (BW = 274; SD = 27 kg), respectively, to evaluate effects of either CON, BM3, or BM3-SOFT silage hybrids on performance and nutrient digestibility in growing diets. In Exp. 1, there was a silage inclusion × hybrid interaction for average daily gain (ADG) and gain-to-feed ratio (G:F). All treatments with 15% silage had greater (P ≤ 0.04) ADG and G:F compared with 45% silage. Cattle fed BM3-SOFT had greater ADG and G:F than cattle fed CON or BM3 when silage was included at 15% of the diet. When silage was fed at 45% of the diet DM, ADG did not differ between cattle fed either bm3 hybrid. Cattle fed BM3 had the greatest G:F (P < 0.01), with no difference between BM3-SOFT and CON. At 15% silage inclusion, hot carcass weight (HCW) was greater (P < 0.01) for cattle fed BM3-SOFT compared with cattle fed CON and BM3 but did not differ between cattle fed BM3 and CON. At 45% silage inclusion, steers fed either bm3 hybrid did not differ in HCW but were both heavier (P < 0.01) compared with cattle fed CON. In Exp. 2, ending BW, dry matter intake (DMI), and ADG were greater (P < 0.01) for steers fed either bm3 hybrid compared to steers fed the CON, but not different between steers fed the bm3 hybrids. There were no differences (P = 0.26) in G:F between the silage hybrids. In Exp. 3, steers fed either bm3 had greater (P < 0.01) neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility than steers fed the CON. Ruminal pH was lower (P < 0.01), and total volatile fatty acid (VFA) concentration was greater (P < 0.01) for steers fed bm3 hybrids compared to steers fed CON. Feeding silage with the bm3 trait improved fiber digestibility, which increased DMI and subsequent ADG in high-forage growing diets. Feeding corn silage with the bm3 trait improved performance compared to non-bm3 corn silage when included above typical roughage concentration.

Impact of Feeding Syngenta Enogen® Feed Corn Compared to Control Corn in Different Diet Scenarios to Finishing Beef Cattle.

The objective of this pooled statistical analysis was to evaluate Syngenta Enogen® Feed Corn (EFC) versus conventional corn (CON) when fed as either dry-rolled corn (DRC) or high-moisture corn (HMC) for effects on finishing beef cattle performance and carcass characteristics. Corns were evaluated in diets with byproduct inclusion rates of 0, 15, 18, 20, and 30% distiller grains or 25 and 35% Sweet Bran® (a commercial corn gluten feed product). Seven trials (n = 1856) consisting of 200 pen means comparing 26 diet treatments were analyzed using regression in a pooled analysis. When EFC was processed as DRC, the gain efficiency (G:F) improved compared with CON, but the response to feeding EFC decreased from a 4.8% improvement to no improvement compared to CON as distiller grains increased from 0 to 30%, but was significantly improved due to feeding EFC in diets with 0 to 18% distiller grains. Feeding cattle EFC as DRC increased the average daily gain (ADG) and G:F by 4.5% compared with CON corn in diets containing Sweet Bran®. No improvements in animal performance were observed when cattle were fed EFC compared to CON when processed as HMC in any situation. Feeding Enogen® corn improved the gain efficiency of finishing cattle compared with conventional corn when processed as dry-rolled corn and fed in diets with less than 20% distillers or diets that include Sweet Bran®.

Effects of replacing wet distillers grains with supplemental SoyPass in forage-based growing cattle diets.

One hundred twenty individually fed steers (initial BW 283 kg ± 32) were utilized in an 84-d growing trial to evaluate the effects of increased metabolizable lysine from non-enzymatically browned soybean meal (SoyPass) in grass hay-based diets containing wet distillers grains plus solubles (WDGS). The treatments were arranged as a 2 × 3 factorial with two levels of protein supplement as 20% (low; DL20) or 35% (high; DL35) of dietary DM using WDGS as the basal protein source, and three increments of SoyPass (SP) replacing 0%, 30%, or 60% of the WDGS DM in the protein supplement yielding six dietary treatments. Average daily gain (ADG), dry matter intake (DMI), gain:feed (G:F), and plasma urea N (PUN) data were analyzed using the MIXED procedure of SAS as a 2 × 3 factorial. Animal was the experimental unit and fixed effects included body weight block, dietary inclusion of distillers grains (DL20, DL35), dietary inclusion of SoyPass (SP) (3 levels), and DL × SP inclusion interactions. Linear and quadratic interactions between DL and SP inclusion were analyzed using covariate regression. No interactions were detected for ADG between SP and DL (P = 0.76). Additionally, SP had no effect on ADG (P = 0.49). However, ADG was increased for steers consuming the DL35 diet compared to DL20 (1.13 vs. 0.86 kg/d, respectively; P < 0.01). A DL × SP interaction was detected for DMI (P = 0.01). As SP replaced WDGS in the DL35 diet, DMI increased linearly from 8.10 to 8.93 kg/d (P = 0.02). In the DL20 diet, DMI was not different as SP replaced WDGS (P ≥ 0.11). Therefore, G:F tended to decrease linearly (P = 0.06) as SP replaced WDGS in the DL35 diet, while no difference (P ≥ 0.11) was detected in the DL20 diet, suggesting SP contained less energy than WDGS but did improve dietary lysine balance. Furthermore, plasma urea nitrogen (PUN) increased linearly as SP replaced WDGS in the DL20 diet (P < 0.01) but was not affected by SP substitution in the DL35 diet (P ≥ 0.19). When WDGS is fed at a low (20% DM) or high (35% DM) inclusion rate in a forage-based diet, replacing the distillers with a source of protected amino acids supplied through heat-treated soybean meal, did not improve performance. A more concentrated or energy-dense form of amino acids may be beneficial in forage-based growing cattle diets containing 20% distillers grains but is not needed in diets with 35% distillers grains.