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Transition of newly received feedlot cattle from a forage- to grain-based diet is challenging, and the appropriate roughage level in receiving diets is debatable. Nutritionists must consider the paradox of dietary transition and roughage level to mitigate ruminal acidosis, yet concomitantly low feed intake presents difficulty in achieving nutrient requirements when metabolic demand is increased due to inherent stress and disease challenge during the receiving period. Previous research suggests that performance is improved at the expense of increased morbidity for newly received cattle consuming diets with less roughage and greater starch concentration. The clinical signs of bovine respiratory disease (BRD) and acute acidosis are analogous; therefore, it is probable that acidotic cattle are incorrectly diagnosed with BRD in both research and production settings. Additional research efforts have attempted to elucidate alterations in microbial populations and digestion, physiological response to inflammatory challenge, and immunological response to infectious bovine rhinotracheitis virus challenge in cattle consuming diets of various roughage levels. Furthermore, our understanding of the rumen microbiome is improving rapidly with culture-independent assays, products such as direct-fed microbials are available, and increased availability and use of fibrous byproduct ingredients requires further attention. Beef cattle nutritionists and producers should consider that the health benefit of receiving diets containing greater levels of roughage and lower energy may not compensate for the reduction in performance compared with feeding receiving diets with lower roughage and greater energy. [ABSTRACT FROM AUTHOR]

The study objectives were to determine the effect of oral hydration therapy and bovine respiratory disease (BRD) on rumination behavior, rumen pH, and rumen temperature. A random subset of high-risk, auction-sourced bulls from 3 truckload blocks (initial BW = 188.9 ± 19.1 kg) were fitted with a collar containing a 3-axis accelerometer to quantify rumination time and activity (n = 58) and administered a rumen pH and temperature data logging bolus (n = 33). At arrival, subset calves (n = 2 per pen) were balanced across treatment pens (n = 15 per treatment; n = 10 animals per pen) and randomized to receive 0.57 L water/45.4 kg BW from a modified oral drenching apparatus (H2O) or no water administration (CON). Standard arrival processing procedures were implemented including surgical castration. Modified-live virus respiratory vaccination was delayed until day 28. Technicians assigned a clinical illness score (CIS) daily; calves with CIS ≥ 2 and rectal temperature ≥ 40 °C were considered a BRD case (RCASE) and treated with an antimicrobial. The fixed effect of BRD cases vs. nontreated cohorts (RCON) was determined retrospectively using data from the accelerometer collar (n = 19 and 29) and rumen bolus (n = 12 and 21, for RCASE and RCON, respectively). Daily means and hourly means across days throughout the 56-d observation period were generated. Fixed effects were analyzed using the mixed model procedure with repeated measures. Daily rumen temperature was altered (P = 0.04) such that peak rumen temperature occurred earlier for H2O, whereas CON had increased (P ≤ 0.01) rumen temperature following delayed vaccination on day 28. Calves diagnosed with BRD had a transiently decreased (P = 0.04) active minutes between days 9 and 32, decreased (P < 0.01) active minutes between 0800 and 2000 h, decreased (P < 0.01) rumination time between 2000 and 0400 h, greater (P < 0.01) rumen temperature until delayed vaccination on day 28, and greater (P < 0.01) hourly rumen temperature between 0900 and 0300, and altered (P < 0.01) rumen pH. Earlier peak rumen temperature observed in H2O may indicate physiological modification enabling a more pronounced inflammatory response. Differences in rumination behavior and activity may be useful for early BRD detection. [ABSTRACT FROM AUTHOR]

To improve animal performance and modify growth by increasing lean tissue accretion, beef cattle production has relied on use of growth promoting technologies such as beta-adrenergic agonists. These synthetic catecholamines, combined with the variable inclusion of rumen degradable (RDP) and undegradable protein (RUP), improve feed efficiency and rate of gain in finishing beef cattle. However, research regarding the impact of beta-adrenergic agonists, protein level, and source on the ruminal microbiome is limited. The objective of this study was to determine the effect of different protein concentrations and beta-adrenergic agonist (ractopamine hydrochloride; RAC) on ruminal bacterial communities in finishing beef heifers. Heifers (n = 140) were ranked according to body weight and assigned to pens in a generalized complete block design with a 3 × 2 factorial arrangement of treatments of 6 different treatment combinations, containing 3 protein treatments (Control: 13.9% CP, 8.9% RDP, and 5.0% RUP; High RDP: 20.9% CP, 14.4% RDP, 6.5% RUP; or High RUP: 20.9% CP, 9.7% RDP, 11.2% RUP) and 2 RAC treatments (0 and 400 mg/day). Rumen samples were collected via orogastric tubing 7 days before harvest. DNA from rumen samples were sequenced to identify bacteria based on the V1-V3 hypervariable regions of the 16S rRNA gene. Reads from treatments were analyzed using the packages 'phyloseq' and 'dada2' within the R environment. Beta diversity was analyzed based on Bray-Curtis distances and was significantly different among protein and RAC treatments (P < 0.05). Alpha diversity metrics, such as Chao1 and Shannon diversity indices, were not significantly different (P > 0.05). Bacterial differences among treatments after analyses using PROC MIXED in SAS 9 were identified for the main effects of protein concentration (P < 0.05), rather than their interaction. These results suggest possible effects on microbial communities with different concentrations of protein but limited impact with RAC. However, both may potentially act synergistically to improve performance in finishing beef cattle. [ABSTRACT FROM AUTHOR]

To improve animal performance and modify growth by increasing lean tissue accretion, beef cattle production has relied on use of growth promoting technologies such as beta-adrenergic agonists. These synthetic catecholamines, combined with the variable inclusion of rumen degradable (RDP) and undegradable protein (RUP), may improve feed efficiency and rate of gain in finishing beef cattle. However, the impact of beta-adrenergic agonists and protein level and source on the ruminal microbiome is limited. The objective of this study was to determine the effect of different protein concentrations and beta-adrenergic agonist (ractopamine hydrochloride; RAC) on ruminal bacterial communities in finishing beef heifers. Heifers (n = 140) were ranked according to body weight and assigned to pens in a randomized complete design to 6 different treatments, containing 3 protein treatments (Control: 13.9% CP, 8.8% RDP, and 5.0% RUP; High RDP: 20.9% CP, 13.4% RDP, 6.1% RUP; or High RUP: 20.9% CP, 9.1% RDP, 10.4% RUP) and 2 RAC treatments (0 and 400 mg/day). Rumen samples were collected from heifers by oral lavage 7 days before harvest. The DNA from the samples were sequenced to identify bacteria based on the V1-V3 hypervariable regions of the 16S rRNA gene using the Illumina MiSeq. Sequences and data from the treatments were analyzed using the R environment and PROC MIXED in SAS 9.4 (SAS Inst.; Cary, NC). Beta diversity was analyzed using PERMANOVA based on PCoA Bray-Curtis distances and were significant among the treatments (P < 0.05). Alpha diversity metrics such as Chao1 and Shannon diversity indices were not significantly different (P > 0.05). Differences among treatments at variable taxonomic levels after analyses through DESeq2 were significantly different for the main effects of protein and RAC, as well as their interaction (P < 0.05). These results suggest possible effects on the microbial communities, potentially acting synergistically to improve performance. [ABSTRACT FROM AUTHOR]

The study objective was to determine the effect of a DNA immunostimulant on recrudescence of bovine herpesvirus-1 (BHV-1) after dexamethasone challenge in beef cattle. It was hypothesized that the DNA immunostimulant would mitigate stress-induced immunosuppression; thereby, reducing the incidence of BHV-1 recrudescence. Steers (n=10) and heifers (n=10; initial BW = 489 kg ± 57 kg) were stratified by pre-existing BHV-1 antibody titer, sex and initial BW and randomly assigned to treatment (n=4 pens/treatment; 2 or 3 animals/pen). All calves were administered 40 mg of dexamethasone i.v. at 0600 h from d 0 to 2, 166-d subsequent to BHV-1 challenge with 1.0 × 108 plaque-forming units per nostril. On d 1, calves were administered treatments consisting of 2 mL i.m. of DNA immunostimulant (Zelnate; ZEL) or sterile saline (CON). Once daily (0600) from d 0 to 12, a whole blood was obtained via jugular venipuncture for complete blood count (CBC) analysis and nasal swabs were collected to determine BHV-1 prevalence via virus isolation testing. A repeated measures mixed model was used to test the effect of treatment, day and their interaction for CBC variables. There was a treatment × day interaction for eosinophils (P = 0.02) and percent eosinophils (P = 0.03). Eosinophils were greater (P < 0.01) for ZEL on d 3 and 6 post-dexamethasone challenge. On d 11 and 12, eosinophils for CON rebounded such that their concentration was greater than ZEL (P < 0.01). Lymphocytes, neutrophil and monocyte concentration did not differ (P ≥ 0.44); however, a day effect (P ≤ 0.01) existed such that each variable increased transiently after dexamethasone challenge. All cattle had BHV-1 present in a nasal swab sample on at least one sample day, with prevalence of BHV-1 in nasal swab samples being greatest on d 5 (80% positive; P = 0.01). However, no treatment differences were detected for BHV-1 prevalence in this study. The DNA immunostimulant altered eosinophil concentrations but did not mitigate BHV-1 recrudesce after dexamethasone challenge [ABSTRACT FROM AUTHOR]

The study objective was to determine the effect of a DNA immunostimulant on recrudescence of bovine herpesvirus-1 (BHV-1) after dexamethasone challenge in beef cattle. It was hypothesized that the DNA immunostimulant would mitigate stress-induced immunosuppression; thereby, reducing the incidence of BHV-1 recrudescence. Steers (n = 10) and heifers (n = 10; initial BW = 489 kg ± 57 kg) were stratified by pre-existing BHV-1 antibody titer, sex and initial BW and randomly assigned to treatment (n = 4 pens/treatment; 2 or 3 animals/pen). All calves were administered 40 mg of dexamethasone i.v. at 0600 h from d 0 to 2, 166-d subsequent to BHV-1 challenge with 1.0 × 108 plaque-forming units per nostril. On d 1, calves were administered treatments consisting of 2 mL i.m. of DNA immunostimulant (Zelnate; ZEL) or sterile saline (CON). Once daily (0600) from d 0 to 12, a whole blood was obtained via jugular venipuncture for complete blood count (CBC) analysis and nasal swabs were collected to determine BHV-1 prevalence via virus isolation testing. A repeated measures mixed model was used to test the effect of treatment, day and their interaction for CBC variables. There was a treatment × day interaction for eosinophils (P = 0.02) and percent eosinophils (P = 0.03). Eosinophils were greater (P < 0.01) for ZEL on d 3 and 6 post-dexamethasone challenge. On d 11 and 12, eosinophils for CON rebounded such that their concentration was greater than ZEL (P < 0.01). Lymphocytes, neutrophil and monocyte concentration did not differ (P ≥ 0.44); however, a day effect (P ≤ 0.01) existed such that each variable increased transiently after dexamethasone challenge. All cattle had BHV-1 present in a nasal swab sample on at least one sample day, with prevalence of BHV-1 in nasal swab samples being greatest on d 5 (80% positive; P = 0.01). However, no treatment differences were detected for BHV-1 prevalence in this study. The DNA immunostimulant altered eosinophil concentrations but did not mitigate BHV-1 recrudesce after dexamethasone challenge [ABSTRACT FROM AUTHOR]

abscesses present significant challenges for the beef industry, yet understanding of the interplay between diet composition, eating behavior, and ruminal acidosis in finishing cattle and their effects on liver abscess prevalence and growth performance is lacking. Therefore, this study investigated the independent and interactive effects of dietary starch concentration and feed delivery regimen on growth performance, rumen buffering characteristics, carcass outcomes, and prevalence of liver abscesses in finishing beef steers. On d 0, beef steers [n = 720; body weight (BW) = 407 ± 4.53 kg) were sorted into 12 blocks according to BW and assigned to 1 of 4 treatments arranged as a 2 × 2 factorial (12 pens/interaction treatment; 24 pens/main effect) in a randomized complete block design. Treatments were finishing diets with low (49.1%; CON) or high (64.4%; HOT) starch concentration fed to steers receiving consistent feed delivery (REG) or randomized variations (ERR) in feed quantity (85% followed by 115% of the previous 4-d average once per week) and delivery time (delayed for 1, 2, 3, or 4 h twice per week). The 3 steers closest to the median BW in each pen were administered a 3-axis accelerometer ear-tag to quantify time spent ruminating and an indwelling rumen bolus to measure ruminal pH for the first 150 d of the study. Fecal score (1 = hard and dry consistency to 5 = water like consistency) and fecal pH were recorded on d 0, 56, 112, and before harvest. Daily dry matter intake (DMI) variability was greatest (P < 0.01; diet × feed delivery interaction) for CON + ERR, intermediate for HOT + ERR, and least for HOT + REG and CON + REG. No additional interactions (P ≥ 0.14) between diet and feed delivery regimen were observed. Feeding HOT increased total liver abscesses (P < 0.01) by 21.7 percentage points and liver scars (P < 0.01) by 12.7 percentage points compared with CON. Additionally, steers consuming HOT had less (P ≤ 0.05) final BW, average daily gain, DMI, gain-to-feed ratio, hot carcass weight, marbling score, and yield grade than CON. Steers fed HOT also had fewer daily rumination minutes (P < 0.01; diet × day interaction), lower fecal pH (P < 0.01; diet × day interaction) lower ruminal pH (P = 0.04), and less desirable fecal scores (P = 0.02) vs. CON. Feed delivery regimen did not affect (P ≥ 0.21) growth performance, rumen buffering characteristics, carcass traits, or liver abscess prevalence. Increasing the concentration of readily fermentable starch fed to finishing steers reduced growth and carcass performance, ruminal pH, and fecal pH, while increasing the proportion of liver abscesses. In contrast, inducing erratic DMI did not affect growth performance or carcass outcomes. [ABSTRACT FROM AUTHOR]

Salmonella can persist in the feedlot pen environment, acting as a source of transmission among beef cattle. Concurrently, cattle that are colonized with Salmonella can perpetuate contamination of the pen environment through fecal shedding. To study these cyclical dynamics, pen environment and bovine samples were collected for a 7-month longitudinal comparison of Salmonella prevalence, serovar, and antimicrobial resistance profiles. These samples included composite environment, water, and feed from the feedlot pens (n = 30) and cattle (n = 282) feces and subiliac lymph nodes. Salmonella prevalence across all sample types was 57.7%, with the highest prevalence in the pen environment (76.0%) and feces (70.9%). Salmonella was identified in 42.3% of the subiliac lymph nodes. Based on a multilevel mixed-effects logistic regression model, Salmonella prevalence varied significantly (P, 0.05) by collection month for most sample types. Eight Salmonella serovars were identified, and most isolates were pansusceptible, except for a point mutation in the parC gene, associated with fluoroquinolone resistance. There was a proportional difference in serovars Montevideo, Anatum, and Lubbock comparing the environment (37.2, 15.9, and 11.0%, respectively), fecal (27.5, 22.2, and 14.6%, respectively), and lymph node (15.6, 30.2, and 17.7%, respectively) samples. This suggests that the ability of Salmonella to migrate from the pen environment to the cattle host--or vice versa--is serovar specific. The presence of certain serovars also varied by season. Our results provide evidence that Salmonella serovar dynamics differ when comparing environment and host; therefore, developing serovar-specific preharvest environmental Salmonella mitigation strategies should be considered. IMPORTANCE: Salmonella contamination of beef products, specifically from the incorporation of bovine lymph nodes into ground beef, remains a food safety concern. Current postharvest Salmonella mitigation techniques do not address Salmonella bacteria that are harbored in the lymph nodes, nor is it well understood how Salmonella invades the lymph nodes. Alternatively, preharvest mitigation techniques that can be applied to the feedlot environment, such as moisture applications, probiotics, or bacteriophage, may reduce Salmonella before dissemination into cattle lymph nodes. However, previous research conducted in cattle feedlots includes study designs that are cross-sectional, are limited to point-in-time sampling, or are limited to sampling of the cattle host, making it difficult to assess the Salmonella interactions between environment and hosts. This longitudinal analysis of the cattle feedlot explores the Salmonella dynamics between the feedlot environment and beef cattle over time to determine the applicability of preharvest environmental treatments. [ABSTRACT FROM AUTHOR]

This study evaluated the impacts of feeding a high-energy finishing diet during both the receiving and finishing period compared with a lower-energy receiving diet with adaptation to the finishing diet on health, performance, serum chemistry, ruminal pH, rumination, and carcass characteristics of high-risk feedlot cattle. Five truck-load blocks of steers (n = 101) and bulls (n = 299) were used in a generalized complete block design and randomly assigned to receive: 1) finishing diet for the entire feeding period (FIN) or 2) receiving diet for the first 56 d, followed by a transition to the finishing diet (REC). All cattle were fed ad libitum and consumed the same diet by day 74. A subset of cattle (n = 48) was randomly selected to quantify ruminal pH, temperature, and rumination time. Ultrasound images were collected on days 0, 74, and 146 to determine fat thickness over the 12th rib and rump, and carcass characteristics were determined after slaughter. Cattle fed FIN had less (P < 0.01) dry matter intake (DMI) from days 0 to 74, but DMI did not differ (P = 0.80) after day 74. From days 0 to final, DMI was 0.26 kg less for FIN compared with REC (P = 0.01). However, calculated metabolizable energy intake was not different from days 0 to 74 (P = 0.19), days 74 to final (P = 0.80), or overall (P = 0.78). Body weight (BW) on day 74 was greater (P < 0.01) and final BW tended to be greater (P = 0.10) for FIN compared with REC. Cattle consuming FIN had greater (P < 0.01) average daily gain and increased (P < 0.01) gain:feed from days 0 to 74. There were no differences (P ≥ 0.31) in health outcomes. On day 74, FIN had greater (P = 0.04) fat thickness over the rump and rib but did not differ (P ≥ 0.52) on day 146. Carcasses of FIN had greater (P = 0.04) hot carcass weight with no difference (P ≥ 0.11) in ribeye area, 12th rib fat thickness, yield grade, or quality grade. There was no difference (P = 0.18) in liver abscess rate. There was a diet × day interaction for blood urea nitrogen (P = 0.02) such that concentration decreased from days 0 to 28 in both treatments, but was less on day 28 for FIN. Ruminal pH was greater on days 2 and 61 and rumination time was less from days 0 to 28 for FIN (diet × day interaction; P < 0.01). Overall, these results suggest that providing a finishing diet fed ad libitum to high-risk calves upon arrival may be a viable alternative to a low-energy receiving diet. [ABSTRACT FROM AUTHOR]

This study evaluated starch dilution with different sources of fiber from terminal implant to harvest on feedlot cattle performance, rumen buffering characteristics, and carcass outcomes. Steers (n = 416) were allocated to 48 pens in a randomized complete block design and assigned to 1 of 4 dietary treatments. Treatments were steam-flaked corn-based diets: CON; 7.5% corn stalks fed for the entire feeding period or CON followed by CS; 14.8% corn stalks, WD; 9.5% wet distillers grains with solubles and 7.5% corn stalks, or NR; 19.0% wet distillers grains with solubles and 0.0% corn stalks fed from terminal implant to harvest. Steers were transitioned to CS, WD, and NR over 6 d using a two-ration system. Within each pen, 2 steers received an indwelling rumen pH bolus and a 3-axis accelerometer ear-tag to quantify rumination. Treatment differences were considered statistically significant when P < 0.10. Dry matter (DM) and metabolizable energy (ME) intake were greatest for cattle consuming CS, intermediate for WD and CON, and least for NR (P < 0.01). The average daily gain (ADG) did not differ among treatments (P = 0.18); however, feed efficiency (G:F) was least for NR, intermediate for WD, and greatest for CS and CON (P = 0.10). Steers consuming CS had more (P = 0.08) 12th rib fat than NR, WD, or CON, but no other differences (P = 0.24) in carcass characteristics were observed. A treatment × day interaction (P < 0.01) was observed for daily rumination time and ruminal pH. Results suggest that increasing the concentration of corn stalks in the diet post-terminal implant increased DM and ME intake and rumination; replacing corn stalks with wet distillers grains with solubles improved G:F and reduced rumination with minimal impacts on ruminal pH. [ABSTRACT FROM AUTHOR]

Both dietary ingredients and technology used in the feedlot cattle industry have evolved in the past 30 years. As consumer concern for the sustainability of the feedlot cattle production increases, it is important to understand how production efficiency and greenhouse gas emissions have changed in this period. For this study, a model was developed to represent feedlot diets and technologies used in 1990 vs. 2020 and evaluate changes in growth performance and carbon footprint. Dietary changes from 1990 to 2020 included the use of byproduct feeds while decreasing corn and dry roughage inclusion rates. In 1990, available technologies included estradiol-only implants and monensin as a feed additive; whereas in 2020 use of combination implants including both trenbolone acetate and estradiol, monensin, and ractopamine hydrochloride (in the final 28 to 42 d) were common. In both 1990 and 2020 use of available technologies increased final body weight (BW), average daily gain (ADG), feed efficiency, and hot carcass weight (HCW) compared to no technology. From 1990 to 2020 initial BW, final BW, ADG, gain to feed ratio, and HCW increased, and dry matter intake decreased. Total days on feed (DOF) also increased by 43 days from 1990 to 2020. Compared to no technology, use of technologies in both 1990 and 2020 decreased total greenhouse gas emissions per animal (CO2e). Because cattle had greater DOF in 2020 than 1990, all sources of greenhouse gas emissions per animal increased. However, when expressed as CO2e/kg BW gain, emissions have decreased by 12.6% because of greater total BW gain in 2020. Feedlots in 2020 produced 48.15% more BW gain with 6.7% less cattle, while only increasing total CO2e by 23.42%, indicating changes in technologies and diet formulations have improved efficiency and reduced the carbon footprint of feedlot cattle production in the past 30 years. [ABSTRACT FROM AUTHOR]

This study evaluated impacts of feeding a finishing diet throughout both the receiving and finishing period compared to a receiving diet with adaptation to the finishing diet on health, performance, ruminal pH, and rumination of high-risk feedlot cattle. Five truck-load blocks of steers and bulls (n = 400) were used in a generalized complete block design and assigned to receive: 1) finishing diet for the entire feeding period (FIN) or 2) receiving diet for the first 56 d, followed by transition to the finishing diet (REC). All cattle were consuming the same diet on d 74. A subset of cattle (n = 48) were randomly selected to quantify ruminal pH, temperature, and rumination time. Ultrasounds were completed on d 0, 74, and 146 to determine fat thickness. Cattle fed REC had greater (treatment × day; P < 0.01) DMI from d 1 to 67 but less DMI from d 74 to 82, and DMI did not differ from d 83 to 174. Energy intake (treatment × day; P < 0.01) was greater for FIN from d 14 to 75. Cattle consuming FIN had greater (P ≤ 0.01) ADG and BW and improved (P < 0.01) gain:feed from day 0 to 74. At d 174, BW of FIN was 9.6 kg greater (P = 0.02). On d 74, FIN had greater (P ≤ 0.05) fat thickness but did not differ (P ≥ 0.61) at d 146. There was no difference (P ≥ 0.31) in health outcomes. Ruminal pH (treatment × day; P < 0.01) was greater for FIN on d 2 and 61, and rumination time was less (P < 0.01) for FIN from d 0 to 28. Overall, these results suggest providing a finishing diet to high-risk calves upon arrival may be a viable alternative to a traditional receiving diet. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of a single slow-release implant compared to two re-implant programs administered at either 120 days on feed (DOF) or 80 days from harvest on performance, carcass characteristics, and activity of serially harvested feedlot cattle. Using a randomized complete block design, steers (n = 4,680) were randomly assigned to 72 pens and 1 of 12 treatments in a 3 × 4 factorial arrangement. Treatments were either a slow-release implant (SR), an initial slow-release implant followed by re-implant at 120 DOF (SR+RI-120), or an initial slow-release implant followed by re-implant 80 days from harvest (SR+RI-80) administered to cattle harvested at 166, 180, 194, or 208 DOF. A 3-axis accelerometer ear-tag was used in a subset (n =1,080) of animals to quantify rumination time and activity. No interactions (P = 0.09) were observed for implant × DOF. Implant did not affect (P = 0.25) final BW, ADG, or DMI, but re-implanted steers had a greater (P < 0.01) G:F ratio than SR. Re-implanted steers also had greater (P = 0.03) HCW, dressed yield, and ribeye area, but less (P < 0.01) backfat, marbling, and empty body fat (EBF) compared to SR. Re-implanted steers had less (P < 0.01) choice and yield grade 4 and 5 carcasses than SR steers. As DOF increased, HCW, dressed yield, backfat, marbling, and EBF increased linearly (P < 0.01). The percentage of choice and yield grade 4 and 5 carcasses also increased (P < 0.01) linearly with additional DOF. An implant × day effect (P < 0.01) for weekly activity minutes suggests re-implanted steers had greater activity after re-implant administration. Re-implanting within the payout period of a slowrelease implant increases feed efficiency, HCW, dressed yield, and activity minutes, but decreases carcass fatness and reduces quality grade regardless of timing of secondary implant administration. [ABSTRACT FROM AUTHOR]