Prevalence Of Liver Abscesses Research Articles

475 Effects of diet composition and feed delivery regimen on growth performance, rumen buffering characteristics, carcass outcomes, and liver abscess prevalence of finishing steers

475 Effects of diet composition and feed delivery regimen on growth performance, rumen buffering characteristics, carcass outcomes, and liver abscess prevalence of finishing steers

Effects of dietary composition and feeding management regimen on liver abscess prevalence, growth performance, and carcass outcomes of feedlot steers*

Effects of dietary composition and feeding management regimen on liver abscess prevalence, growth performance, and carcass outcomes of feedlot steers*

Removing tylosin phosphate from finishing diets with increasing roughage concentrations affects growth performance, carcass characteristics, and prevalence of liver abscesses of finishing steers*

Removing tylosin phosphate from finishing diets with increasing roughage concentrations affects growth performance, carcass characteristics, and prevalence of liver abscesses of finishing steers*

165 Comparing corn earlage to a blend of corn silage and grain when fed at two different inclusions for finishing cattle

Abstract An experiment was conducted to evaluate the effects of feeding earlage as the sole source of roughage and grain in a finishing diet when compared with corn silage plus grain at equal forage NDF inclusions in the diet. Crossbred yearling steers [n = 216; initial body weight (BW) = 471 ± 14.1kg] were fed one of 4 experimental diets in a 2 × 2 factorial treatment arrangement with roughage type and forage inclusion being the 2 factors. Treatment diets were formulated for earlage to provide all the grain the diet (74%) which provided 14.8% forage and was compared with 29.6% corn silage and 44.4% corn as a 50:50 blend of dry rolled corn (DRC) and high moisture corn (HMC). The other two diets were formulated for corn silage to provide a standard roughage inclusion for finishing diets (i.e., corn silage at 15% to supply 7.5% forage in the diet). To match 7.5% roughage with earlage providing all the roughage, another diet included earlage at 37%, with an additional 37% corn included as the 50:50 blend of HMC and DRC. All diets included 20% wet distiller’s grains (WDGS) and 6% supplement. The two inclusions of forage were either 7.5 or 14.8% forage as either earlage or corn silage. Earlage was assumed to provide 20% forage and corn silage to provide 50% forage, on a DM basis. Cattle were stratified into 3 BW blocks, then assigned randomly assigned to pens within block, and treatment assigned randomly to pens. A total of 24 pens containing 9 steers in each were used with pen as the experimental unit. Feeding performance, carcass characteristics and liver abscess prevalence were evaluated using the MIXED procedure of SAS with BW block and treatment being fixed effects. No interactions between roughage type or forage inclusion were observed for performance or carcass traits (P > 0.13) except for marbling or liver abscesses (P < 0.09). When cattle were fed a diet with corn silage as the roughage source, greater dry matter intakes (DMI) and average daily gain (ADG) were observed (P ≤ 0.01), but feed efficiency was not significantly different (P = 0.35). However, when evaluating effects of NDF inclusion, cattle fed 7.5% forage in the diet were 6.8% more efficient than cattle fed 14.8% forage and tended to have greater gain (P = 0.10), but no significant differences were observed for intake (P = 0.11). These data suggest that cattle fed earlage will eat and gain less than cattle fed a blend of corn silage and grain when estimated forage is equivalent, and when earlage is fed as the sole source of grain, cattle will be less efficient than when conventional roughage inclusions are fed.

Evaluation of Precision Ingredient Inclusion on Production Efficiency Responses in Finishing Beef Cattle

Two randomized complete block design experiments evaluated the influence that varying degrees of ingredient inclusion accuracy in a finishing diet have on growth performance and carcass traits. Treatments included (1) normal inclusion tolerance with a 0.454 kg tolerance for all ingredients (CON) or (2) variable inclusion tolerance where each ingredient was randomly increased or decreased but the targeted as-fed quantity for the daily delivery was met (VAR). In Experiment. 1, black Angus heifers (n = 60; initial shrunk BW = 460 ± 26.2 kg) were used in a 112 d experiment. Ten pens in total (5 pens/treatment, 6 heifers/pen) were used. The targeted diet (DM basis) consisted of high-moisture ear corn (75%), dried distiller’s grains (20%), and a liquid supplement (5%). As-fed inclusion rates for DDGS and LS varied from formulated targets by −20, −15, −10, −5, 0, +5, +10, +15 or +20%. The HMEC inclusion was adjusted so that the targeted as-fed amount of the diet was delivered daily. Treatment did not alter ADG, DMI, G:F, HCW, dressing percentage, rib-eye area, rib fat, USDA marbling score, KPH, yield grade, retail yield, empty body fat, or body weight at 28% estimated EBF, nor liver abscess prevalence or severity (p ≥ 0.15). In Exp. 2, Charolais–Angus cross steers (n = 128; initial shrunk BW = 505 ± 32.1 kg) were used in a 94 d experiment. Steers were assigned to pens (8 pens/treatment; 8 steers/pen) and one of the two management strategies used in Exp. 1 was employed. Ractopamine HCl was fed (300 mg per head daily) during the final 28 d. Diets consisted of (DM basis) dry-rolled corn (63%), dried distiller’s grains plus solubles (15%), liquid supplement (5%), grass hay (7%), and corn silage (10%). Ingredient inclusions were randomized in the same manner as Exp. 1, except LS inclusion was held constant. Corn silage inclusion was adjusted so that the targeted as-fed amount of the diet was delivered each day. Steers from VAR had increased (p = 0.01) DMI, but similar (p = 0.75) ADG resulting in reduced (p ≤ 0.02) G:F and growth-performance-predicted Net Energy for maintenance and gain. Treatment did not influence (p ≥ 0.38) HCW, dressing percentage, rib-eye area, rib fat, KPH, yield grade, retail yield, empty body fat, or body weight at 28% estimated EBF. A tendency for an increased USDA marbling score (p = 0.08) was noted in VAR. Under the conditions of this experiment, randomly altering ingredient proportions can impact growth performance and efficiency measures depending upon the type of finishing diet fed.

Effect of Lighter and Heavier Initial Weight on Growth Performance and Carcass Traits of Single-Source Beef Steers.

The objective of the study was to determine the influence that initial BW has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in feedlot steers. Charolais×Red Angus steers (n = 70) selected from a larger single-source group were used in a 209-d growing-finishing feedlot experiment. Steers were assigned to two groups based on initial BW (light initial weight, LIW = 273 ± 16.0 kg; heavy initial weight, HIW = 356 ± 14.2 kg) and allotted into 10 pens (n = 7 steers per pen; 5 pens per experimental group) the within pen standard deviation for LIW was from 14.1 kg to 20.9 kg and for HIW was from 13.7 kg to 16.0 kg. Steers were fed a common diet once daily. Experimental data were analyzed as a randomized complete block design with pen as the experimental unit. LIW steers had a greater cumulative HH change (p = 0.04). A treatment × day interaction (p = 0.05) was observed for HH with HIW steers having a greater HH at all time points. Final BW and carcass-adjusted (HCW/0.625) BW were greater for HIW steers by 13.1% and 13.4% respectively (p ≤ 0.01). HIW steers had a greater DMI (p = 0.01) compared to LIW. Cumulative ADG was greater for HIW by 3% (p = 0.04). LIW steers had better feed conversion (p = 0.01). HIW steers had greater (p ≤ 0.05) HCW, marbling scores, and yield grade (YG), with decreased REA/HCW (p = 0.01) compared to LIW. The distribution of USDA Yield Grade was altered by initial BW (p = 0.04). No differences were detected (p ≥ 0.22) for the distribution of Quality grade nor liver abscess prevalence and severity. Regression coefficients did not differ between LIW and HIW for urea space calculations of empty body water, fat, or protein (p ≥ 0.70). A quadratic response was noted for empty body fat (EBF), empty body water (EBH20), and carcass protein (CP). In conclusion, HIW steers had greater growth, but poorer feed efficiency compared to LIW steers. Steers with a HIW produced fatter carcasses with a greater degree of marbling.

Effect of traditional roughage-based or limit-fed, high-energy diets on growth performance and digestion in newly received growing cattle and subsequent implications on feedlot growth performance and carcass characteristics.

The objective was to determine the effects of ad libitum-fed roughage-based diets or limit-fed high-energy diets on growth performance, behavior, health, and digestion in newly received growing cattle and subsequent implications on feedlot growth performance and carcass characteristics. In experiment 1, 409 crossbred heifers (initial body weight [BW] = 279 ± 24kg) in 32 pens were used in a randomized block design. Heifers were fed one of two dietary treatments: a total mixed ration with 0.99 Mcal net energy for gain (NEg)/kg dry matter (DM) fed ad libitum (0.99AL) or 1.32 Mcal NEg/kg DM limit-fed at 85% of intake of heifers fed 0.99AL (1.32LF85%). Both diets contained 40% DM as a branded wet corn gluten feed. In experiment 2, 370 crossbred heifers (initial BW = 225 ± 20kg) were used in a randomized block design and were fed a diet formulated to contain 0.99 Mcal of NEg/kg DM for ad libitum intake or a diet formulated to contain 1.32 Mcal of NEg/kg DM and fed at 2.2% of BW daily (DM basis; 1.32LF2.2). For experiments 1 and 2, treatment integrity was maintained through the finishing phase where cattle were fed a common diet. Cattle were sorted by BW into heavy and light groups prior to finishing, with light cattle fed longer than heavy cattle to reach similar harvest BW. In experiment 3, eight ruminally cannulated heifers (average BW = 305 ± 23kg) were used in a 2-period cross-over design and fed treatments from experiment 1 to assess digestibility and ruminal fermentation characteristics. Gain:feed was 47% and 35% greater (P < 0.01) in experiments 1 and 2, respectively, for limit-fed heifers compared with 0.99AL heifers. Rumination time was greater (P < 0.01) for 0.99AL compared with limit-fed treatments in experiments 1 and 2. Activity was greater (P < 0.01) for 1.32LF2.2 than for 0.99AL in experiment 2. In experiment 1, more (P = 0.03) carcasses from light-sort heifers than carcasses from heavy-sort heifers had livers with large, active abscesses. In experiment 2, finishing phase morbidity was greater (P < 0.01) for 1.32LF2.2 than for 0.99AL. Light-sort groups had fewer (P < 0.01) edible livers than heavy-sort groups, suggesting that greater number of days on feed may increase the risk of liver abscess prevalence and condemnation. In experiment 3, apparent total-tract DM and organic matter digestibilities were greater (P < 0.01) for 1.32LF85% than for 0.99AL. Overall, dietary treatments during the growing phase had little carryover effect on feedlot growth performance, carcass characteristics, or liver abscesses prevalence at harvest.

106 Using a Novel Direct-Fed Microbial as an Alternative for Tylosin Phosphate to Control Liver Abscesses and Decrease Antimicrobial Use in Finishing Beef Steers

Abstract Our objective was to evaluate the use of a novel direct-fed microbial as an alternative to antimicrobials to decrease liver abscesses in feedlot cattle. Angus beef steers (n = 240; initial BW = 263 ± 18.0 kg) were used in a randomized complete block design comprised of 3 BW blocks and 3 pen replications per treatment. Experimental treatments were randomly assigned to pen within BW block and consisted of: 1) negative control, dietary supplement contained no tylosin phosphate (NCON); 2) positive control, dietary supplement contained tylosin phosphate (PCON); 3) positive control with tylosin phosphate removed the last 65 d of the feeding period (PCONW); and 4) novel direct-fed microbial fed at 1 g mixture/animal with 1 × 1011 CFU/g (DFM). By design, initial BW did not differ (P = 0.79) among treatments, and at the end of the 59-d receiving period, there were no differences in final BW (P = 0.25). From d 0 to d 30, ADG, DMI, DMI as a percentage of BW, and G:F did not differ (P ≥ 0.21). Likewise, ADG, DMI, DMI as a percentage of BW, and G:F, from d 31 to d 59, were not different (P ≥ 0.30). From d 0 to d 59, there were no differences in ADG, DMI, DMI as a percentage of BW, nor G:F (P ≥ 0.20). During the finishing period, live- and carcass-adjusted final BW did not differ (P ≥ 0.57) among treatments. During the finishing period, there were also no differences in ADG, DMI, DMI as a percentage of BW, or G:F (P ≥ 0.17). Carcass-adjusted ADG, DMI as a percentage of BW, and G:F also did not differ (P ≥ 0.16). Across treatments, no differences in HCW were noted (P = 0.84). Dressing percentage, marbling score, longissimus dorsi (LM) area, 12th-rib fat thickness, and calculated yield grade (YG) were not different among dietary treatments (P ≥ 0.32). Liver abscess incidence and severity were not affected by dietary treatments (P ≥ 0.13). The inclusion of a novel direct-fed microbial in finishing cattle diets did not affect growth performance, carcass characteristics, nor the prevalence of liver abscesses. However, the removal of tylosin phosphate 65 d before harvest numerically resulted in the lowest frequency of severe liver abscesses when compared with steers not fed tylosin phosphate.

104 Development of an Experimental Model to Induce Liver Abscesses in Steers Using an Acidotic Diet Challenge and Oral Bacterial Inoculation

Abstract The objective of this study was to develop a model for liver abscesses (LA) in Holstein steers by using an acidotic diet or acidotic diet plus intraruminal inoculation of Fusobacterium necrophorum, Salmonella enterica serotype Lubbock, and Truperella pyogenes. Holstein steers (n = 40; initial BW = 84.9 + 7.1 kg) were individually housed and randomly assigned to either a negative control diet (CON), an acidotic diet (AD), or an acidotic diet plus intraruminal inoculation with the bacterial mixture [ADB; (1 × 109 colony forming unit (CFU)/mL of each bacteria]. Steers in AD and ADB were cycled on (3 d) and off (2 d) a high-starch diet 20 days before intraruminal inoculation of ADB. Following inoculation, AD and ADB remained on the acidotic diet for the remainder of the study. Ruminal pH boluses were randomly inserted into 19 steers across treatments to monitor ruminal pH throughout the study. Steers were euthanized and necropsied to record gross pathology on the lung, rumen, liver, and colon. Culture techniques were used to determine the prevalence inoculated bacteria within LA. Quantitative polymerase chain reaction methods were used to quantify F. necrophorum in rumen tissue. Data were analyzed as a completely randomized design with animal as the experimental unit, where an α of ≤ 0.05 determined significance. Liver abscess prevalence was 43% in ADB vs. 0% in AD and CON treatments (P &amp;lt; 0.01). Ruminal damage was 51.1% greater in ADB than in AD and 78.6% greater than in CON (P ≤ 0.05). There were no pathological differences in the lungs and colons among treatment groups (P ≥ 0.14). There was a treatment × time interaction for ruminal pH, where pH decreased below 5.6 in AD and ADB calves during each cycle of the acidotic diet (P &amp;lt; 0.01). The ADB contained a greater concentration of F. necrophorum subsp. Necrophorum and subsp. Fundliforme within rumen tissue (P ≤ 0.03). Of the LA cultured, 100% contained F. necrophorum, 50% S. enterica, and 0% contained T. pyogenes. The F. necrophorum subsp. Necrophorum was phylogenetically typed and identical to the strain (FN-8LI) infused in the bacterial inoculation. These data suggest that acidotic diet in combination with intraruminal inoculation of the bacterial mixture is sufficient to induce liver abscesses and provides insight on possible mechanisms and origins of LA. Further studies are needed to validate these results and determine if this model may be used to study novel intervention methods.

PSXII-14 Effects of Feeding 10-G on Performance and Carcass Quality of Yearling Beef Steers

Abstract Life Products’ direct fed microbial, 10-G, is a lipid-coated and heat protected mixed culture containing Lactobacillus acidophilus, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillus brevis, and Lactobacillus plantarum. Previous small-pen research has reported inconsistent benefits to performance and carcass characteristics from feeding 10-G. The objective of this trial was to evaluate the effects of feeding 10-G on growth performance and carcass quality in yearling steers. In this randomized complete block design, 6,400 yearling steers were allocated to treatment (10-G or control) within a block (n = 16), where pen served as experiment unit. Trial diets were composed of steam-flaked corn, wheat silage, corn silage, and Sweet Bran Plus. The addition of 10-G within the treatment diet was at an inclusion of 2 g·animal-1·day-1 to provide 1x109 cfu for approximately 170 days. Mean initial body weight was 358 kg and cattle were on feed for an average of 182 days. No differences (P &amp;gt; 0.10) were observed between treatments for dry matter intake (control: 9.75 vs 10-G: 9.80 kg), final body weight (control: 641vs 10-G: 641 kg), average daily gain (control: 1.55 vs 10-G: 1.55 kg/d), or feed efficiency (control: 2.85 vs 10-G: 2.87). When evaluating carcass characteristics, there were no differences (P &amp;gt; 0.10) for hot carcass weight (control: 415 vs 10-G: 413 kg) or liver abscess prevalence (control: 17.4 vs 10-G: 18.2%). However, dressed carcass yield was decreased (P = 0.05) by 0.17% for cattle fed 10-G (control: 64.51 vs 10-G: 64.34%). No differences (P &amp;gt; 0.10) were observed for marbling score (control: Small29 vs 10-G: Small27), ribeye area (control: 100.00 vs 10-G: 100.00 cm2), backfat thickness (control: 1.30 vs 10-G: 1.30 cm). USDA quality grade outcomes. In conclusion, the supplementation of 10-G direct fed microbial did not influence live or carcass performance within this trial.

371 Effect of Calcium Magnesium Carbonate And/Or Tylosin Phosphate Supplementation on Behavior, Rumination Activity, Feedlot Growth Performance and Carcass Characteristics in Yearling Beef Steers

Abstract The objective of this study was to evaluate the effects of calcium magnesium carbonate (CMC) and/or tylosin phosphate (TYL) supplementation on behavior, rumination activity, growth performance and carcass characteristics of yearling beef steers. Treatments were arranged in a 2 × 2 factorial including CMC and TYL. Beef steers (n = 156; 469 ± 18 kg) were randomly assigned to treatment pens (7 to 8 steers/pen) with pen (n = 20 pens total, 10 pens/main effect mean, and 5 pens/simple effect mean) as experimental unit. Cattle were transitioned from a 30% roughage diet to a 7% roughage finishing diet based on dry-rolled corn, dried distillers grains plus solubles, liquid supplement, and oat silage over the initial 20 d period. The CMC was included at 1.5% of the diet (DM basis) in replacement of dry-rolled corn and TYL was provided at 90 mg·animal·d-1. Behavior and rumination activity were monitored during a 24 h period on d 42. Data was collected on a pen-basis, every 10 min from 0800 h to 0750 h the next day and included minutes spent drinking (DR), eating (EA), active (AC), ruminating (RU), and resting (RE). Cattle were shipped for harvest on d 105 to a commercial beef abattoir. Growth performance was calculated on a carcass-adjusted basis (HCW/0.625). Data were analyzed as a randomized complete block design with fixed effects of CMC, TYL, or their interaction; block was a random effect. An interaction was observed between CMC and TYL for time spent DR (P = 0.03) and RU (P = 0.01). Control steers ruminated 28% longer compared with CMC/-TYL steers (P = 0.05) and 20% longer than -CMC/TYL steers (P = 0.05). The main effect of CMC tended to increase time spent EA by 19.3% (P = 0.06). Dry matter intake was decreased (P ≤ 0.02) by 4.57% when CMC was fed and increased by 1.96% when TYL was fed. However, no difference (P ≥ 0.26) was observed for G:F or gain efficiency in either treatment. No differences (P ≥ 0.28) were observed in any dietary net energy utilization outcomes in either main effect treatment. Carcass weight tended (P = 0.07) to be lighter with CMC supplementation compared with CON (432 vs 439 kg). Supplementation of TYL resulted in a 11.7% reduction (P = 0.04) in percentage of abscessed livers. No differences (P ≥ 0.12) were observed in DP, marbling, YG, or EBF in either main effect treatments. These results indicate that supplementation of CMC did not result in any appreciable improvements in growth, carcass or dietary net energy utilization performance, but TYL supplementation resulted in a positive effect on liver abscess prevalence.

311 Evaluation of Rumen Protected B-Vitamin Blend on Finishing Steer Growth Performance, Efficiency of Dietary net Energy Utilization, Carcass Trait Responses, and Liver Abscess Prevalence and Severity

Abstract The objective of this study was to determine the influence that a rumen-protected B-vitamin (RPBV) blend (containing pantothenic acid, pyridoxine, folic acid, biotin, and cyanocobalamin; Vivalto, Trouw Nutrition, Isola Vicentina, Italy) had on growth performance, efficiency of dietary net energy utilization, carcass trait responses, and liver abscess severity and prevalence in beef steers fed a finishing diet. Steers (n = 246; initial shrunk body weight (BW) = 411 ± 25.8 kg) from two sources, were used in a 126-d randomized complete block design experiment. Within 48 h after arrival, steers were individually weighed and allotted to one of 24 pens (n = 10 to 12 steers; 8 pens/treatment) and randomly assigned to 1 of 3 treatments: 1) No RPBV; 2) RPBV1 at 1 g/hd/d; 3) RPBV2 at 2 g∙animal-1∙d-1/. During the first 14 d cattle received two transition diets. From d 15 to d 126 cattle were fed the final diet containing 53% dry-rolled corn; 23% corn silage; 20% MDGS; and 4% suspended supplement. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with treatment as the fixed effect and block (Pen location) as the random effect; pen was considered the experimental unit. No differences (P ≥ 0.13) were found for dry matter intake, final live BW, average daily gain (ADG), or feed efficiency (G:F) among treatments. Carcass-adjusted final BW, ADG, and G:F were not influenced by treatment (P ≥ 0.59). Hot carcass weight, dressing percentage, marbling score, kidney-pelvic-heart fat, or BW at 28% empty body fat did not differ among treatments (P ≥ 0.11). Rib eye area (REA) was altered (quadratic effect, P = 0.02) by treatment; steers from RPBV 1g had decreased REA compared with others. Additionally, calculated yield grade (YG) and calculated retail yield (RY) were altered (quadratic effect, P ≤ 0.01) by treatment; steers from RPBV 1 g had increased YG and decreased RY compared with others. Estimated empty body fatness tended (P = 0.06) to be greater from steers fed RPBV compared with control. Overall USDA YG distribution was altered by dietary treatment (P = 0.01). The proportions of YG1 and YG5 carcasses were unaffected by treatment, but there was a shift in the proportion of carcasses that graded YG2, YG3, and YG4 among treatments. Distribution of USDA Quality Grade was not altered by treatment (P = 0.53). No differences were observed on liver abscesses among treatments. The use of RPBV altered carcass muscularity and rib fat accumulation which impacted the overall YG distribution. However, RPBV did not appreciably influence any cumulative growth performance measures liver abscess incidence or severity.

312 Evaluation of Dietary Roughage Manipulation During the Feeding of Ractopamine Hydrochloride as a Method to Improve Ruminal Health and Control Liver Abscess Severity in Feedlot Steers

Abstract The objective of this study was to determine if additional roughage inclusion to feedlot steer finishing diets during the feeding of ractopamine hydrochloride (RH) is an effective method to improve rumen health and control liver abscess severity. Steers [n = 64; initial shrunk body weight (SBW) = 633 kg ± 35.1 kg] were sourced from an unrelated trial and remained in their previous study pens; pens (n = 8) were assigned to dietary treatment in a completely randomized design. All steers on trial were fed a common 7% [dry matter (DM) basis] roughage equivalent (RE) finishing diet composed of dry-rolled corn, dried distillers grains plus solubles, corn silage, and grass hay for the 58 d preceding study initiation. Steers were fitted with rumination tags to track daily rumination. Dietary treatments were CON: no diet change; and 12R: 5% (DM basis) RE addition to diet via grass hay during the feeding of RH. Steers were fed RH (300 mg/steer/d), finished on treatment diets for 28 d, and harvested at a commercial beef processor. Growth performance, efficiency of dietary net energy (NE) utilization, and continuous carcass data were analyzed with pen as the experimental unit (EU) and fixed effect of treatment. Minutes ruminating was analyzed as an analysis of covariance with individual animal as the EU, fixed effects of treatment, days on feed (DOF) and their interaction, and baseline minutes ruminating as a covariate in the model. Liver abscess prevalence, rumen health, and categorical carcass data were analyzed with the Fisher’s exact test to determine differences between treatments. No difference (P ≥ 0.19) was observed for final SBW, average daily gain, dry matter intake, feed conversion efficiency, dressing percentage, hot carcass weight, calculated yield grade, marbling score, 12th rib fat thickness, calculated empty body fat, observed dietary NE for maintenance and gain, observed-to-expected dietary NE for maintenance and gain, or distribution of liver abscess prevalence, ruminitis score, or USDA yield grade. Ribeye area tended (P = 0.10) to differ between treatments with 12R steers exhibiting a 3.5% larger ribeye. Distribution of USDA quality grade differed (P = 0.003) between treatments with 12R steers having 25% more carcasses grading USDA average choice or better. A treatment × DOF interaction (P = 0.045) was observed for minutes ruminating per day. Daily minutes ruminating was increased (P ≤ 0.05) for 12R on d 1, 2, and 20 and tended to be increased (P ≤ 0.10) for 12R on days 10, 13, 24, and 25. Inclusion of an additional 5% RE to finishing cattle diets during a 28 d RH feeding period can be a management strategy to decrease risk of digestive upsets without sacrificing growth performance or carcass quality.

262 Evaluation of a Single Growing-Finishing Diet for Single Source, pre-Conditioned Beef Steers of Lighter (273 kg) and Heavier (356 kg) Initial Body Weight (BW)

Abstract The objective of the study was to determine the influence that initial BW has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in feedlot steers. Crossbred Charolais steers from a single source, (n = 70; initial BW = 329 ± 72.6 kg) were used in feedlot experiment at the Ruminant Nutrition Center, in Brookings, SD, during a 209-day growing-finishing period. These steers represented the lightest and heaviest proportions of steers taken from a larger group of 265 steer calves. On d 0 and d 1 BW and hip height (HH) measurements were collected for allotment proposes, and the initial experimental BW was the average between d 0 and d 1 BW. Steers were allocated to 1 of 2 treatments: 1) lighter (276 ± 16 kg; LIW) or 2) heavier (356 ± 16 kg; HIW) initial BW and allotted to 10 pens (n = 7 steers/pen; 5 pens/treatment). Steers were fed a diet containing 16% roughage once daily. Data were analyzed as a randomized complete block design with pen as the experimental unit. Treatment was included as a fixed effect and block (location) was considered a random effect in the statistical model. The LIW steers had a greater cumulative HH change compared with HIW. Final BW and carcass-adjusted (HCW/0.625) BW were greater for HIW steers by 13.1% and 13.4% respectively (P ≤ 0.01). The HIW steers had a 14.4% greater DMI (P = 0.01) compared with LIW. Cumulative ADG was greater for HIW by 3% (P = 0.04). LIW steers had improved feed conversion (P = 0.01) by 11.3% compared with HIW. The HIW steers had greater (P &amp;lt; 0.05) HCW (15.5%), marbling scores (6.8%), and Yield grade (16.0%), and decreased REA/HCW (P = 0.01) by 5.9% compared with LIW. Steers from HIW tended to have greater rib fat (P = 0.09) by 15% compared with LIW. The distribution of USDA Yield grade was altered by initial BW (P = 0.04) with a shift in proportions of steers with greater numerical Yield grades for steers in HIW compared with LIW. No differences were detected (P ³ 0.22) for the distribution of Quality grade or liver abscess prevalence and severity. In conclusion, HIW steers had greater growth, but poorer feed efficiency compared with LIW steers. Steers with a HIW produced fatter carcasses with a greater amount of marbling.

Evaluation of a ruminally protected blend of pantothenic acid, pyridoxine, folic acid, biotin, and vitamin B12 on finishing steer growth performance, efficiency of dietary net energy utilization, carcass trait responses, and liver abscess prevalence and severity.

The objective of this study was to determine the influence that a ruminally-protected B-vitamin (RPBV) blend (containing vitamin B5, B6, B7, B9, and B12) had on growth performance, efficiency of dietary net energy utilization, carcass trait responses, and liver abscess severity and prevalence in beef steers fed a finishing diet. Steers (n = 246; initial shrunk body weight [BW] = 411 ± 25.8 kg) from two different sources, were used in a 126-d RCBD experiment. Within 48 h after arrival, steers were individually weighed and allotted to 1 of 24 pens (n = 8 to 12 steers; 8 pens per treatment) and randomly assigned to 1 of 3 treatments: (1) No RPBV; (2) RPBV1 at 1 g/steer d-1; 3) RPBV2 at 2 g/steer d-1. During the first 14 d, cattle received two transition diets with increasing concentrate. From days 15 to 126, cattle were fed the final diet containing 53% dry-rolled corn; 23% corn silage; 20% MDGS; and 4% suspended supplement. On the first 28 d, steers of RPBV1 had a greater average daily gain (ADG) and better feed conversion (G:F), both by 9% (quadratic effect, P ≤ 0.02). However, cumulatively, no differences (P ≥ 0.13) among treatments were found for dry-matter intake (DMI), live final BW, ADG, or G:F. Carcass-adjusted final BW, ADG, and G:F were not influenced by treatment (P ≥ 0.59). Additionally, carcass weight, dressing percentage, marbling score, kidney-pelvic-heart fat, or BW at 28% empty body fat did not differ among treatments (P ≥ 0.11). Ribeye area (REA) was altered (quadratic effect, P = 0.02) by treatment; steers from RPBV1 had decreased REA compared to others. Additionally, calculated yield grade (YG) and calculated retail yield (RY) were altered (quadratic effect, P ≤ 0.01) by treatment; steers from RPBV1 had increased YG and decreased RY compared to others. Estimated empty body fatness tended (P = 0.06) to be greater from steers-fed RPBV compared to control. Overall USDA YG distribution was altered by dietary treatment (P = 0.01). The proportions of YG1 and YG5 carcasses were unaffected by treatment, but there was a shift in the proportion of carcasses that graded YG2, YG3, and YG4 among treatments. Distribution of USDA Quality Grade was not altered by treatment (P = 0.53). No treatment differences in liver abscess incidence or severity were observed (P = 0.13). The use of RPBV altered carcass muscularity and rib fat accumulation affecting the overall YG distribution. However, RPBV did not appreciably influence any cumulative growth performance measures or liver abscess outcome.

PSVII-14 Evaluation of Precision Feeding on Production Efficiency Responses in Finishing Beef Cattle

Abstract Angus heifers (n = 60; initial shrunk BW = 460 ± 26.2kg in n = 10 pens; 5 replicate pens/treatment) were used in a 112-d feedlot finishing experiment to evaluate animal growth performance outcomes, efficiency measures, and carcass characteristics when varying degrees of ingredient inclusion tolerances were imposed. Treatments included: 1) Normal feeding with 1lb tolerance for all ingredients (FIXED). 2) Variable inclusion strategy where each ingredient was randomly increased or decreased but the targeted as-fed quantity for the daily delivery was met (VAR). All heifers were fed once daily with all bunks managed using a slick bunk approach. Monensin sodium was fed at 33mg/kg and ractopamine HCl was fed (300mg per head daily) the final 28d. Individual BW measures were captured at processing and every 21d. Diets consisted of earlage, dried distiller’s grains, and a liquid supplement. Ingredient inclusions were randomized by assigning independently a random integer to DDGS and LS with each integer corresponding to the deviation from targeted inclusions. Earlage inclusion was adjusted so that the targeted as-fed amount of the diet was delivered. As-fed inclusion rates varied from formulated targets by -20, -15, -10, -5, 0, +5, +10, +15, or +20%. Actual DM inclusion was within 5% of expectations 72% of the time in FIXED (13periods/18periods) and only 27% of the time in VAR (5periods/18periods). Ingredient inclusion accuracy did not affect ADG, DMI, or feed conversion efficiency in this experiment (P ≥ 0.15). DMI and liquid inclusion rates showed an inverse relationship. There were no differences (P ³ 0.35) detected between treatments for carcass characteristics. No differences were noted between dietary treatments for liver abscess prevalence or severity. Under the conditions of this experiment, randomly altering ingredient proportions did not affect live animal performance, efficiency measures, or carcass characteristics.

Invited review: a carcass and meat perspective of crossbred beef × dairy cattle.

Crossbreeding dairy cows with beef sires has greatly altered the consist of U.S. dairy-influenced slaughter cattle and generated an influx of crossbred beef × dairy cattle to the U.S. fed beef slaughter supply in 2021. This review provides a summary of our observations of carcass and meat traits in the recent U.S. beef × dairy crossbred population and, based on these observations, exposes future opportunities for consideration. Strip loin steaks from beef × dairy cattle can be marketed alongside conventional beef products in retail display without consumer discrimination based on color or steak shape previously experienced in steaks from straightbred dairy cattle. Additionally, beef from crossbred beef × dairy cattle cannot be discriminated against for eating quality attributes (tenderness, flavor, and juiciness) as it exhibits similar, if not improved, performance of these attributes to beef from conventional beef cattle. We have also demonstrated that live expression of beef-type versus dairy-type character within the beef × dairy crossbred population has minimal effect on eating quality. With proper genetic selection and management, crossbred beef × dairy cattle can capture carcass premiums from an optimal combination of carcass quality (marbling) and red meat yield. Future beef × dairy crossbred mating and management systems should emphasize increases in total carcass muscling and reductions in liver abscess prevalence. A story of quality, sustainability, and traceability in the large and constant supply of beef from crossbred beef × dairy cattle may present profitable branding and marketing opportunities for these products.

PSIII-6 Relationship of geographical location, cattle type, sex, and pen size to rates of liver abnormalities

Abstract Bovine liver abscess outcomes of individual animals (n = 989,296) were observed from 2013 to 2021 on a pen (n = 6,420) basis to quantify liver abscess prevalence and severity, as well as other liver abnormalities such as liver flukes. Cattle originated from 122 feedlots located in Arizona, Colorado, Idaho, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas. Livers were audited at eighteen different beef abattoirs. Observational categories included sex (heifer, steer), cattle type (Holstein, beef-type), and pen count. Pen counts were grouped (&amp;lt; 40, 41–80, 81–160, 161–320, and &amp;gt;320) to quantify the association of pen size on liver abscess outcomes. Data were analyzed as a series of binomial proportions using generalized linear mixed models with fixed effects of observational categories (cattle type, feedyard location, pen size and sex). Cattle fed in Oklahoma or Texas exhibited greater (P &amp;lt; 0.01) frequency of liver flukes (3.2% vs 0.5%) than cattle fed in Colorado or Nebraska. Cattle fed in Colorado, Kansas, Missouri, Nebraska, Arizona, and Oklahoma exhibited fewer (P &amp;lt; 0.01) total abscesses (23.5%, 26.0%, 23.6%, 19.3%, 16.9%, and 18.1%) than cattle fed in Idaho, Minnesota, and Texas (36.4%, 36.4%, and 33.2%). Beef-type cattle were observed to exhibit fewer (P &amp;lt; 0.01) total abscesses (22.0% vs 41.1%) and fewer (P &amp;lt; 0.01) severe abscesses (10.2% vs 26.4%) than Holstein cattle. Likewise, native heifers exhibited fewer (P &amp;lt; 0.01) total abscesses (20.6% vs 23.3%) and fewer (P &amp;lt; 0.01) severe abscesses (9.3% vs 11.1%) than native steers. Abscess prevalence differed as a function of pen size. Both total abscess and severe abscess rates decreased (P &amp;lt; 0.01) as animal count within a pen increased (32.66%, 27.47%, 27.86%, 23.17%, and 20.33%; 17.20%, 14.48%, 14.80%, 11.45%, and 9.14%). These results suggest liver abscess prevalence and severity is affected by a wide range of factors.

Effects of corn stalk inclusion and tylosin on performance, rumination, ruminal papillae morphology, and gut pathogens associated with liver abscesses from finishing beef steers

To reduce prevalence of liver abscesses in finishing beef steers, we must evaluate the possibility of pathogens originating from the hind gut as well as the rumen. We hypothesized that pathogens promoting liver abscess formation are located throughout the gut, and increased dietary roughage levels could improve gut integrity over time. Two hundred sixty-three crossbred beef steers (BW = 258 ± 29 kg) were used in a randomized complete block design with 7-8 hd/pen (8 pens/treatment) using a 2 × 2 factorial treatment structure. Steers received steam-flaked corn-based diets with 5 or 15% corn stalk (CS) inclusion (dry matter basis, DMB) and with (TYL) or without (NTYL) tylosin (7.9 g/T; DMB). Half of the pens in each treatment remained on feed for the entire experiment duration (Exp 1) whereas the remaining half were designated for serial slaughter (Exp 2). Steers were fed each day at 0700 h for an average of 220 d (heavy block = 175 d, light block = 233 d). For Exp 2, eight steers were slaughtered on d 0 to obtain initial tissue samples and thereafter one pen/treatment was slaughtered every 56 d. During serial slaughter, dorsal and ventral sac rumen tissue samples were collected for histopathological evaluation along with ruminal, ileal, and colonic tissues for bacterial isolation. Data were analyzed using mixed models; pen was the experimental unit for performance outcomes and individual animal was the experimental unit for bacterial isolation and histopathological data. No interaction (P ≥ 0.40) between tylosin and CS inclusion was detected for ADG or final BW. Interactions were detected for DMI and G:F; both outcomes were similar when tylosin was included in the diet, however both outcomes differed notably without tylosin. Perimeter and length of ventral rumen papillae decreased (P ≤ 0.01) as DOF increased. In contrast, dorsal rumen papillae perimeter and length increased through d112 and then decreased through d231. Corn stalk inclusion rate did not affect the incidence of bacterial species isolated from the ruminal (P = 0.38), ileal (P > 0.15), or colonic (P > 0.37) epithelial tissues. Cattle consuming the TYL diets tended to have decreased (P = 0.06) presence of ileal Fusobacterium necrophorum subsp. necorphorum and increased (P = 0.07) rates of ruminal Salmonella enterica compared to NTYL. Prolonged consumption of a finishing diet, regardless of CS or TYL inclusion, seemed to be the major source of change in rumen epithelial tissue morphology.

PSIV-19 Relationship between liver abscess microbiome of feedlot cattle and soil organic matter microbiome isolated from feedlot pens

Abstract Liver abscess (LA) prevalence has increased 15% for beef cattle and 25% for Holstein cattle. The prevalence of liver abscesses in the Central Plains region (CR) is greater than the Southwest region (SR) of the United States. The objective was to evaluate soil organic matter (SOM) microbiome of feedlot pens, associated LA microbiomes, and the impact of breed, location, and tylosin. Eighty-three commercial feedlot pens were sampled for SOM prior to harvesting and LA samples were collected from two commercial packing plants in Tolleson, AZ (SR) and Greely, CO (CR). Liver abscess samples were linked to SOM samples. Amplification and sequencing of the V4 variable region of the 16S rRNA gene was performed using the Illumina MiSeq. Bacterial phyla, genera, and diversity indices were reported for LA and SOM samples. Reported data is from a subset of five pens. The most prevalent genera identified in liver abscesses were Fusobacterium (64.2%) and Bacteroides (18.6%). Predominant SOM genera were Atopostipes (13%) and Clostridium (10%). Phylum SOM Shannon Weiner Index (SWI) was lower for the CR compared to the SR (0.034 vs. 0.174; P &amp;lt; 0.05), indicating a dominant bacterium in the CR. Atopostipes and Clostridium comprised 48% of the CR SOM, explaining the lower SWI. The SWI of SOM and liver abscesses of Holsteins are lower (P &amp;lt; 0.05) compared to beef counterparts. Additionally, Clostridium, Fusobacterium, and Atopostipes populations were greater (P &amp;lt; 0.05) in SOM of Holstein pens than beef pens. Genus richness was lower (P &amp;lt; 0.05) for both SOM and liver abscesses from pens of cattle fed tylosin vs. no tylosin. There is a negative correlation between SOM SWI and LA% (R2 = -0.49; P = 0.03) and LA severity (A+) (R2 = -0.44; P = 0.05). In conclusion, SOM may serve as a potential vector for liver abscesses.