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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.

Objective Our objective was to evaluate subsequent feedlot performance and carcass characteristics of steers that previously grazed endophyte-infected fescue and received either a mineral only (MIN) supplement or a cumulative management (CM) strategy. Materials and Methods Grazing occurred in autumn and winter of 2018 and 2019 with feedlot finishing after grazing. Within year, 60 fall-weaned steers (282 ± 7.7 kg) were randomly assigned to either MIN (n = 3) or CM (n = 3) pastures. The CM strategy include a steroidal growth implant, monensin, and 1% BW (as-fed basis) of 1:1 corn gluten feed:soybean hull mix. During feedlot finishing, steers were penned to maintain pasture groups. Results and Discussion Steers receiving CM were heavier (P = 0.002) entering the feedlot and finished 40 d earlier than MIN (161 vs. 201 ± 5.7 d, P Implications and Applications A CM strategy increases weight of steers grazing toxic fescue. This additional weight can reduce the days required for feedlot finishing without influencing carcass characteristics. Improved grazing performance and fewer days for feedlot finishing may reduce environmental impact.

Experimental bovine respiratory syncytial virus (BRSV) infection can enhance Histophilus somni (Hs) disease in calves; we thus hypothesized that modified-live virus (MLV) vaccines containing BRSV may alter Hs carriage. Our objective was to determine the effects of an intranasal (IN) trivalent (infectious bovine rhinotracheitis virus [IBRV], parainfluenza-3 virus [PI3V], and BRSV) respiratory vaccine with parenteral (PT) bivalent bovine viral diarrhea virus (BVDV) type I + II vaccine, or a PT pentavalent (BVDV type I and II, IBRV, BRSV, and PI3V) respiratory vaccine, on health, growth, immunity, and nasal pathogen colonization in high-risk beef calves. Calves (n = 525) were received in five truckload blocks and stratified by body weight (213 ± 18.4 kg), sex, and presence of a pre-existing ear-tag. Pens were spatially arranged in sets of three within a block and randomly assigned to treatment with an empty pen between treatment groups consisting of: 1) no MLV respiratory vaccination (CON), 2) IN trivalent MLV respiratory vaccine with PT BVDV type I + II vaccine (INT), or 3) PT pentavalent, MLV respiratory vaccine (INJ). The pen was the experimental unit, with 15 pens/treatment and 11 to 12 calves/pen in this 70-d receiving study. Health, performance, and BRSV, Hs, Mycoplasma bovis (Mb), Mannheimia haemolytica (Mh), and Pasteurella multocida (Pm) level in nasal swabs via rtPCR was determined on days 0, 7, 14, and 28, and BRSV-specific serum neutralizing antibody titer, and serum IFN-γ concentration via ELISA, were evaluated on days 0, 14, 28, 42, 56, and 70. Morbidity (P = 0.83), mortality (P = 0.68) and average daily gain (P ≥ 0.82) did not differ. Serum antibodies against BRSV increased with time (P0.01). There was a treatment × time interaction (P0.01) for Hs detection; on days 14 and 28, INT (21.1% and 57.1%) were more frequently (P0.01) Hs positive than CON (3.6% and 25.3%) or INJ (3.4 % and 8.4%). Also, INT had reduced (P = 0.03) cycle time of Hs positive samples on day 28. No difference (P ≥ 0.17) was found for IFN-γ concentration and Mb, Mh, or Pm detection. The proportion of Mh positive culture from lung specimens differed (P0.01); INT had fewer (0.0%; 0 of 9) Mh positive lungs than INJ (45.5%; 6 of 13) or CON (74.0%; 14 of 19). Vaccination of high-risk calves with MLV did not clearly impact health or growth during the receiving period. However, INT was associated with an altered upper respiratory microbial community in cattle resulting in increased detection and level of Hs.Our objective was to determine the safety, efficiency, and effects on immunity and nasal shedding of respiratory pathogens for high-risk cattle administered an intranasal (IN), trivalent (infectious bovine rhinotracheitis virus [IBRV], parainfluenza-3 virus [PI3V], and bovine respiratory syncytial virus [BRSV]) respiratory vaccine with parenteral, bivalent bovine viral diarrhea virus (BVDV), or a parenteral, pentavalent (BVDV type I and II, IBRV, BRSV, and PI3V) respiratory vaccine, compared to an unvaccinated negative control. The results of this study indicate that modified-live virus (MLV) vaccination of high-risk calves upon arrival, either parenterally or intranasally, did not clearly impact health or growth during the feedlot receiving period. However, cattle that were intranasally vaccinated had increased carriage of Histophilus somni in the naris, greater amount of H. somni in nasal swabs indicated by reduced PCR cycle time, and less frequent culture of Mannheimia haemolytica from lung tissue samples upon necropsy. Therefore, intranasal administration of MLV vaccines may alter the microbial community and balance of opportunistic pathogens in the respiratory tract of cattle.

This study evaluated the effects of Sweet Bran (SB) and wet distillers grains with solubles (WDGS) in the diet alone or in combination on physically effective neutral detergent fiber (peNDF), ruminal pH, and rumination behavior of finishing beef cattle. For this study, 455 steers (373 ± 15.5 kg) were allocated to 48 pens in a randomized complete block design. Treatments (n = 12 pens per treatment) were one of four steam-flaked corn-based diets containing no corn-milling products (CON), 20% WDGS (WDGS20), 20% SB (SB20), or 20% SB and 10% WDGS (COMBO). Within each pen, two steers were randomly selected to receive an indwelling ruminal pH bolus to quantify ruminal pH and a 3-axis accelerometer tag to measure rumination for the first 92 d of the study. Diet samples were collected weekly to determine particle size, neutral detergent fiber (NDF) concentration, and peNDF. Physically effective NDF was calculated using both the proportion of particles > 4.0 mm (peNDF4.0) and the proportion of particles > 8.0 mm (peNDF8.0). The percentage of particles > 4.0 mm was greatest (P < 0.01) for CON, intermediate for SB20, and least for WDGS20 and COMBO. Both NDF (P < 0.01) and peNDF4.0 (P < 0.01) were greatest for COMBO, intermediate for WDGS20 and SB20, and least for CON. The percentage of particles > 8.0 was greatest (P < 0.01) for CON, intermediate for WDGS20 and SB20, and least for COMBO, but peNDF8.0 did not differ (P = 0.40). A diet × day interaction (P < 0.01) was observed for daily rumination minutes per kg of DMI, NDF, peNDF4.0, and peNDF8.0. A diet × hour interaction (P < 0.01) was observed where CON cattle spent less time ruminating at 0800 and 1000 h in a 24 h period. Daily ruminal pH was greatest (P < 0.01) for COMBO, intermediate for SB20 and WDGS20, and least for CON. A diet × hour interaction (P < 0.01) was also observed for circadian ruminal pH, where pH was least for CON from 0800 to 1800 h. Relationships between peNDF, rumination behavior, and ruminal pH observed in this study suggest that SB and WDGS similarly enhance rumen buffering capacity when steam-flaked corn is replaced in the diet.

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 (P0.01) 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 (P0.01) and final BW tended to be greater (P = 0.10) for FIN compared with REC. Cattle consuming FIN had greater (P0.01) average daily gain and increased (P0.01) 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; P0.01). 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.When high-risk cattle arrive at the feedlot, they have low feed consumption and a greater risk for disease because of stress, inflammation, and exposure to pathogens. Because of reduced feed consumption, newly arrived cattle may not be able to meet their energy requirement for growth during the first several weeks after feedlot arrival. Therefore, providing a high-energy finishing diet (FIN) when stressed cattle arrive at the feedlot may allow for greater growth performance and improved health when compared with a traditional, low-energy receiving diet that contains more roughage (REC). Our study evaluated this concept and we observed that cattle fed FIN had greater body weight, average daily gain, and gain:feed (G:F) within the first 56 d when the different diets were fed, with no difference in growth performance after the cattle consuming REC transitioned to FIN on day 74. However, cattle consuming FIN had greater hot carcass weight and G:F over the entire feeding period. There were no differences in health outcomes among treatments. Overall, providing a high-energy finishing diet to high-risk cattle upon arrival to the feedlot improved growth performance with no impact on health.

Objective Our objective was to compare metaphylaxis with tulathromycin (META) and vaccination with a pentavalent modified-live virus respiratory vaccine (MLV) in high-risk feedlot calves and their influence on health and growth performance during a 56-d receiving period. Materials and Methods Beef bulls (n = 372) and steers (n = 106) were stratified by initial BW (234 ± 1.32 kg), health status, and sex and randomly assigned to treatments arranged in a 2 × 2 factorial: (1) no META or MLV (CON), (2) META administration on d 0 (META), (3) MLV administration on d 0 with revaccination on d 14 (MLV), and (4) META and MLV administration (META+MLV). Interactions and main effects were analyzed within a generalized complete block design using a mixed statistical model with 10 pen replicates per treatment. Body weight and feed refusals were recorded periodically to determine interim and overall (d 0 to 56) performance and feed efficiency. A subset (n = 256) was affixed with a 3-axis accelerometer ear-tag to quantify activity and rumination time. A 7-d postmetaphylactic interval was implemented for META, and bovine respiratory disease cases were determined by treatment-blinded, trained investigators. Results and Discussion The META groups had greater ADG from d 0 to 14, from d 14 to 28, and overall (P ≤ 0.01) and BW on d 56 was increased (P Implications and Applications Health and performance of high-risk feedlot cattle was improved by META but not MLV.

Objective Use of monensin during the stocker phase of production has been suggested as a possible cause of reduced response to monensin during finishing. Experiments were conducted to determine the carryover effects of monensin supplementation during the stocker phase and effects of feeding monensin during the finishing phase on performance and efficiency of beef steers. Materials and Methods Steers were fed hay or grazed cool-season annuals or bermudagrass in Arkansas before finishing in Canyon, Texas (blocks 1 and 2) or Stillwater, Oklahoma (block 3). Treatments were arranged as a 3 × 2 factorial with 3 monensin doses during the stocker phase (0, 882, or 1,764 g/t offered in a free-choice mineral) and 2 levels during finishing (0 or 37.5 mg/kg of diet DM). There were no block × treatment interactions (P ≥ 0.19) for performance or carcass measurements; therefore, data were pooled across blocks and finishing locations. Results and Discussion Stocker × finishing treatment interactions were not observed for finishing performance and efficiency data (P ≥ 0.50). There was no carryover effect on overall finishing performance or efficiency. Cattle consuming monensin during the finishing phase had decreased (P Implications and Applications Supplementation of monensin to stocker cattle before finishing did not affect subsequent finishing efficiency response to monensin during finishing. Providing monensin in finishing diets still decreases DMI and improves feed efficiency of finishing cattle.

Vaccination is the act of administering a vaccine, whereas immunization may occur if appropriate time is allowed for a competent host immune system to respond to the antigen contained in a vaccine. Timing is critical to ensure bovine respiratory disease (BRD) vaccine safety, efficacy, and efficiency. The current review provides temporal considerations of BRD vaccination within the North American beef production system with focus on vaccination timing in high-risk, newly received beef stocker and feedlot cattle.

Objective This research compared whole blood and serum analyses from cattle with and without liver abscesses to quantify differences associated with the presence and severity of liver abscesses in fed beef steers. Materials and Methods Blood samples for complete blood count and sera were collected from fed Holsteins (n = 153; 51 samples from cattle with no, minor, and major abscesses) approximately 30 s after exsanguination; liver abscesses were visually assessed after evisceration. Data were analyzed using mixed model ANOVA and logistic regression procedures; carcass was the experimental unit. Results and Discussion Of the complete-blood-count variables analyzed, platelet counts were increased (P = 0.02) and hemoglobin and hematocrit values (P Implications and Applications These results indicate that cattle with major liver abscesses undergo physiologic differentiation, which can be detected in whole blood and serum. This baseline research improves our understanding of the systemic influences of liver abscesses. Identifying blood parameter outcomes associated with liver abscesses antemortem may allow future useful implications for cattle welfare and feedlot management.

Objective The objective was to assess activity of steers grazing tall fescue pastures varying in toxicity with and without a combination management practice including supplemental feed, ionophore, and a steroidal implant. Materials and Methods Activity of steers was monitored using IceQube (IceRobotics Ltd., Edinburgh, UK) accelerometers. Steers grazed 1 of 15 pastures differing in ergovaline (EV) in spring 2016. For 7 pastures, steers were offered mineral-only (MIN) management (MGMT). In the remaining pastures, steers received a cumulative (CM) MGMT strategy including 1% BW, 1:1 corn gluten feed:soybean hulls, 150 mg/head per day monensin, and a steroidal implant containing 40 mg of trenbolone acetate, 8 mg of estradiol, and 29 mg of tylosin tartrate. Physical activities—lying bouts, steps, and standing time—were reported in 2 periods: period 1 (27 d) and period 2 (26 d). Results and Discussion Period 1 lying bouts were not different for MGMT (P = 0.11) or EV (P = 0.26). Period 2 lying bouts exhibited a MGMT × EV interaction (P = 0.02). Time steers spent standing was not different between CM and MIN during period 1 (P = 0.79) but differed during period 2 (P Implications and Applications Behavioral changes due to EV and MGMT appeared more prevalent during period 2 when warmer weather and changing forage quality would be expected to worsen the effects of fescue toxins. The CM may elicit greater satiety or reduce heat stress. Strategies that improve productivity of cattle on toxic fescue may also improve welfare as expressed through physical activity changes.

1.1 Background:Bovine respiratory disease (BRD) is caused by interactions among host, environment, and pathogens. The current standard for antemortem pathogen identification in cattle with BRD is deep-guarded nasopharyngeal swabbing, which is challenging, costly, and waste generating. The objective was to compare the ability to recover Mannheimia haemolytica and compare microbial community structure using 29.5 inch (74.9 cm) deep-guarded nasopharyngeal swabs, 16 inch (40.6 cm) unguarded proctology swabs, or 6 inch (15.2 cm) unguarded nasal swabs when characterized using culture, real time-qPCR, and 16S rRNA gene sequencing. Samples for aerobic culture, qPCR, and 16S rRNA gene sequencing were collected from the upper respiratory tract of high-risk cattle 2 weeks after feedlot arrival. 1.2 ResultsThere was high concordance of culture and qPCR results for all swab types (results for 77% and 81% of samples animals completely across all 3 swab types for culture and qPCR respectively). Microbial communities were highly similar among samples collected with different swabs types, and differences identified relative to treatment for BRD were also similar. Positive qPCR results for M. haemolytica were highly concordant (81% agreed completely), but samples collected by deep-guarded swabbing had higher Ct values (Kruskal-Wallis analysis of variance on ranks, P < 0.05; Dunn-test for pairwise comparison with Benjamini-Hochberg correction, P < 0.05) and lower frequency of positive compared to nasal and proctology swabs (McNemar’s Chi-square test, P M. haemolytica by culture, 16S rRNA microbiome, and qPCR.

This study evaluated the plasma oxidative products of beef calves challenged with LPS following methionine supplementation (L0 = Control; L1 = 10 g/hd · d; L2 = 20 g/hd · d). Following an initial 40-d feeding period, steers (n = 32; 379kg±30.7) were challenged i.v. with LPS (0.25 µg/kg body weight) on d 41. Blood was collected at -2, 0, 2, 4, 6, 8, 10, 12, 18, 24, 36 and 48 h relative to the LPS challenge at 0 h. Samples were processed to isolate plasma for indicators of oxidative stress with colorimetric assays determining malondialdehyde (MDA) and reactive oxygen species (ROS) concentrations. Data were analyzed as repeated measures using the GLIMMIX procedure of SAS. Concentrations of MDA varied by time (P < 0.001), showing a large increase (P < 0.05) 2 h post-LPS, then decreasing again at 4 h. MDA values decreased (P < 0.05) from h 6 to 18 where values returned to initial concentrations (P < 0.05). A treatment × time interaction (P < 0.001) occurred for ROS concentrations. Concentrations for all treatments were less than the detectable limit at -2, 0, 10, 12, 24, 36, and 48h (P > 0.05). At 2 h post-LPS, ROS was greatest in L0 cattle, least in L2, and intermediate in L1 (P < 0.05), but declined at 4 h in all treatments. Values peaked at 6 h for L1 and L2 cattle, followed by a decline at 8 h (P < 0.05). Control cattle were similar from 4 to 6 h (P > 0.05) but increased again at 8 h (P < 0.05). These data show that oxidative stress from an LPS challenge contributes to increased plasma ROS and secondary lipid oxidation products but may be mitigated by the inclusion of methionine supplements.

Bovine Respiratory Disease (BRD) is the most devastating disease affecting cattle producers in North America. Vaccines and antimicrobials are commonly used to prevent and treat BRD. However, it is still a growing problem. The four common BRD opportunistic pathogens, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis, are present in the upper respiratory tract of healthy cattle as well, and how they move to the lung are unknown. The apparent role of the respiratory microbiome in BRD has led to many microbiome studies. However, most culture-independent studies have focused on the opportunistic pathogens, and little is known about the potential bacterial probiotics in the prevention and treatment of BRD. This study aims to identify potential probiotics to treat and prevent BRD by analyzing respiratory microbiotas (nasal swabs (NS): healthy: n=94, BRD: n=94; nasopharyngeal swabs (NPS): healthy: n=25, BRD: n=36; and bronchoalveolar lavage (BAL): healthy: n=22, BRD: n=29) from clinically healthy calves at feedlot entrance and calves at BRD diagnosis. Amplicon sequence variants (ASVs) were classified as potential probiotics if selected as a top predictor by a machine learning technique (random forest) and significantly more abundant in healthy controls (log2fold change ≥ 2 and P

The study objective was to evaluate health, performance, and antimicrobial costs of heifers where targeted metaphylaxis was guided by a commercial blood leukocyte analyzer compared to a traditional metaphylaxis regimen. Using a randomized complete block design, heifers (n=1,271; initial body weight (BW) = 233.3±1.08 kg) were randomly allocated to treatment pens (n=20; 10 blocks). Treatments were: 1) cattle administered metaphylactic treatment with gamithromycin at arrival (META), and 2) cattle administered metaphylaxis with gamithromycin according to the blood leukocyte analyzer outcome (TARGETED). The blood leukocyte analyzer indicated immune status of individual animals according to the number and proportion of different leukocytes in the blood; red signified “abnormal” and green signified “normal” status. Only cattle with a red outcome were administered antimicrobial in the TARGETED treatment. Of all cattle enrolled in the study, 73% were deemed normal and 27% were deemed abnormal by the chute side blood analyzer. Treatment groups had an equal distribution of normal (META = 73% TARGETED = 74%) and abnormal (META = 28% TARGETED = 26%) cattle enrolled in the study. Cattle were fed a common starter ration for the duration of the 62-d study. Pen riders were blinded to treatment pen status. Data was analyzed using PROC MIXED and GLIMMIX in SAS. Final BW, ADG, and feed conversion were less for TARGETED (P≤0.02). However, the arrival processing antimicrobial cost (META = 11.77 and TARGETED = $3.27/heifer) and total antimicrobial cost (META = 17.77 and TARGETED = $9.12/heifer) was reduced (P< 0.01) for TARGETED. TARGETED had an arrival processing antimicrobial cost savings of $8.50/heifer and an overall drug input cost savings of $8.65/heifer. The BRD morbidity rate for normal status heifers was 18.85% and more than abnormal (26.49%; P< 0.01). Normal status heifers had a mortality rate of 3.17 vs. 5.80% for abnormal (P=0.03). In conclusion, drug costs were reduced but performance of TARGETED was also less.

Two groups (light = 740 lbs and heavy = 942 lbs) of Akaushi cross steers (n = 20), were ultrasounded for carcass traits by an Ultrasound Guidelines Council Certified Technician every 28 days to quantify differences in intramuscular fat deposition occurring in three distinct muscles (longissimus dorsi, biceps femoris and semitendinosus). Cattle were fed at the West Texas A&M University Research Feedlot and scanned with an Aloka 500 ultrasound unit using Beef Image Analysis (BIA) Feedlot software from Designer Genes Technologies, Inc. (Harrison, AR). Carcass ultrasound measurements included 12-13th rib ribeye area (REAU), subcutaneous fat thickness (FTU), intramuscular fat percentage along the longissimus dorsi (IMFULD), rump fat thickness (RFU) as well as intramuscular fat percentage of the biceps femoris (IMFUBF) and semitendinosus (IMFUST). A difference was detected in IMFULD for the duration of the study (P < 0.05). However, no differences occurred from day 0 to day 56 (P = 0.34), or from day 84 to day 140 (P = 0.17) for IMFULD. There was a slight numerical decrease (0.1505%) in IMFUBF from day 0 to day 56, with an increased difference from day 56 to day 84 (P < 0.05). There was a positive change from 4.113% to 5.728% in the heavy group (P = 0.08) and a change from 4.113% to 4.456% in the light group (P = 0.42) for IMFUBF. There was a significant change in IMFUST from day 56 to 84 (P < 0.05). Of note, there was a decrease in IMFULD, IMFUBF and IMFST from day 140 to day 168 which could be associated with adverse winter weather events. The data present a positive increase throughout all muscles studied for beef cattle while on feed, though weather events have the possibility to negatively affect gains more rapidly than progressive effects associated with feed and growth.

Background Bovine respiratory disease (BRD) is caused by interactions among host, environment, and pathogens. One standard method for antemortem pathogen identification in cattle with BRD is deep-guarded nasopharyngeal swabbing, which is challenging, costly, and waste generating. The objective was to compare the ability to recover Mannheimia haemolytica and compare microbial community structure using 29.5 inch (74.9 cm) deep-guarded nasopharyngeal swabs, 16 inch (40.6 cm) unguarded proctology swabs, or 6 inch (15.2 cm) unguarded nasal swabs when characterized using culture, real time-qPCR, and 16S rRNA gene sequencing. Samples for aerobic culture, qPCR, and 16S rRNA gene sequencing were collected from the upper respiratory tract of cattle 2 weeks after feedlot arrival. Results There was high concordance of culture and qPCR results for all swab types (results for 77% and 81% of sampled animals completely across all 3 swab types for culture and qPCR respectively). Microbial communities were highly similar among samples collected with different swab types, and differences identified relative to treatment for BRD were also similar. Positive qPCR results for M. haemolytica were highly concordant (81% agreed completely), but samples collected by deep-guarded swabbing had lower amounts of Mh DNA identified (Kruskal–Wallis analysis of variance on ranks, P P P Conclusions Though differences existed among different types of swabs collected from individual cattle, nasal swabs and proctology swabs offer comparable results to deep-guarded nasopharyngeal swabs when identifying and characterizing M. haemolytica by culture, 16S rRNA gene sequencing, and qPCR.

Available energy plays a critical role in the initiation and maintenance of an immune response to a pathogen, a process that is further altered by activation of the stress system. This study was designed to determine the effect of an acute vs chronic stress model on the metabolic response to vaccination in naïve beef steers. Steers (n = 32; 209 ± 8 kg) were blocked by body weight (BW) and randomly assigned to one of three treatments: 1) Chronic stress (CHR), 0.5 mg/kg BW dexamethasone (DEX) administered i.v. at 1000 h on day 3 to day 0; 2) Acute stress (ACU), 0.5 mg/kg BW DEX administered i.v. at 1000 h on day 0 only; or 3) Control (CON), no DEX. On day −4, steers were fitted with jugular vein catheters and moved into individual bleeding stalls in an environmentally-controlled facility. Blood samples were collected at −74, −50, and −26 h, at 0.5-h intervals from −4 to 6 h, and at 12, 24, 36, 48, and 72 h relative to vaccination with a combination vaccine (Pyramid 5 + Presponse SQ, Boehringer Ingelheim Animal Health USA, Duluth, GA) at 1200 h on day 0. Data were analyzed by the MIXED procedure of SAS specific for repeated measures. There was a treatment × time interaction (P < 0.001) for serum glucose concentrations. Specifically, glucose concentrations increased at −50 h in CHR steers and at 1200 h in ACU steers and remained elevated through 72 h postvaccination period in these two treatments compared to CON steers. The change in nonesterified fatty acid (NEFA) concentrations relative to baseline values was affected by treatment and time (P < 0.001) such that the change in NEFA was greater in CHR (0.06 ± 0.01 mmol/L), followed by CON (−0.01 ± 0.01 mmol/L) and ACU steers (−0.04 ± 0.01 mmol/L). There was a tendency (P = 0.08) for a treatment × time interaction for change in serum NEFA concentrations. Serum urea nitrogen (SUN) was affected by treatment and time (P < 0.001) such that SUN concentrations were greatest in CHR (12.0 ± 0.1 mg/dL) followed by ACU (10.4 ± 0.1 mg/dL) and CON steers (9.6 ± 0.1 mg/dL); however, the treatment × time interaction was not significant (P = 0.12). These data demonstrate that activation of the stress and immune axes using an acute or chronic stress model can increase energy mobilization prior to and following vaccination in naïve steers, potentially affecting available energy needed to mount an adequate antibody response to vaccination.

Vaccination is a critical component of cattle health management. Effective cattle vaccine programs should consider the timing of vaccination in relation to expected disease challenge, risk for wild-type exposure of various bovine pathogens, and host factors during vaccination. Nearly all consulting veterinarians recommend vaccination of stressed, high-risk calves on feedlot arrival. However, this recommendation fails to consider several factors associated with vaccine efficiency. Further research evaluating vaccine interactions in stressed cattle and potential additive effects of endotoxin from multiple bacterin administration may reveal new evidence-based vaccination guidelines for cattle in the various segments of beef and dairy production systems.

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.

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.

Our objective was to evaluate the effect of oral hydration therapy with water during initial processing of high-risk crossbred beef calves on health and performance during a 56-d feedlot receiving period. In Exp. 1, 6 arrival blocks of heifers (n = 664, initial BW = 197.1 ± 5.8 kg) were randomized to treatment pens (n = 6 per treatment). In Exp. 2, 3 arrival blocks (initial BW = 188.9 ± 19.1 kg) of bulls (n = 242) and steers (n = 55) were stratified by sex and purchase BW and randomly assigned to treatment pens (n = 15 per treatment) before initial processing. In both experiments, calves received either 0.57 L of water/45.4 kg of BW from a modified oral drenching apparatus (H2O) or no water administration (CON) at initial processing. Treatment-blinded technicians evaluated calves daily and assigned a clinical illness score for bovine respiratory disease (BRD). Cattle qualifying for BRD treatment were administered an antimicrobial. In Exp. 1, BW, ADG, and G:F did not differ (P ≥ 0.63); however, H2O numerically increased DMI (5.29 vs. 5.09 kg/d; P = 0.12) and tended to increase BRD morbidity (29.0 vs. 21.5%; P = 0.07). There was no difference (P ≥ 0.39) in second or third BRD morbidity rate or mortality rate. In Exp. 2, final BW (256.8 vs. 248.7 kg) and overall ADG (1.19 vs. 1.07 kg/d) tended to increase (P = 0.08) and DMI from d 42 to 56 (7.54 vs. 6.85 kg/d) was greater (P

Bovine respiratory disease (BRD) detection is a major challenge in feedlot cattle management. In a pilot study, two dogs were trained using sets of three samples to identify nasal swabs from cattle that developed signs of BRD after feedlot arrival. Cattle arrived at the feedlot in four lots and included a mixture of bulls (n=306) and steers (n=89). In the final stage of training, Dog A accuracy was 0.82 (95% CI: 0.79-0.85) and Dog B accuracy was 0.63 (95% CI: 0.60-0.67). A Kruskal-Wallis test identified differences in accuracy across lots (P < 0.001). Differences between pairs were identified by Wilcoxon tests. Accuracy for Lot 2 (0.53, 95% CI: 0.46-0.59) was lower than all other lots. The greatest accuracy, 0.96 (95% CI: 0.92-1.00), was for sets where the positive sample came from a different lot than both negative samples, and differed from accuracy for all lots except Lot 4. A Wilcoxon test detected no differences (p = 0.76) in accuracy between sets that consisted of all bulls (0.73, 95% CI: 0.69-0.76) and sets that were a mixture of bulls and steers (0.72, 95% CI: 0.69-0.75). After training, in a double-blind detection test, unfamiliar samples (n=123) were presented to the dogs as 41 sets. Each set was evaluated twice by each dog. Accuracy for Dog A was 0.39 (95% CI: 0.28-0.50), no better than chance; however, Dog B’s accuracy was 0.45 (95% CI: 0.34-0.56), better than the 0.33 expected by chance. In the detection test, neither sample lot (p = 0.33) nor sex (p = 0.11) impacted performance for either dog. Dogs’ consensus accuracy was 0.54 (95% CI: 0.38-0.69). Overall, dogs showed some ability to discriminate between BRD-affected and healthy cattle using nasal swabs, however multiple compounding factors may have influenced canines’ decision making in this trial.

The objective of this study was to evaluate antioxidant capacity in plasma of beef calves challenged with LPS. Following an initial feeding period of 40 d, steers (n = 32; 379 kg ± 30.7) were transported to the Livestock Issues Research Unit’s Bovine Immunology Research and Development Complex and challenged intravenously with LPS (0.25 µg/kg BW) on d 41. Blood samples were collected via jugular catheter at -2, 0, 2, 4, 6, 8, 10, 12, 18, 24, 36 and 48 h relative to the LPS challenge at 0 h. Blood samples were processed to isolate plasma for indicators of oxidative stress with a colorimetric assay to determine ferric reducing antioxidant power (FRAP) values via concentration of ferrous iron (µM). Data were analyzed as repeated measures using the GLIMMIX procedure of SAS. Antioxidant values did vary with time (P < 0.001) being greater (P < 0.05) at -2, 0, 2, 36, and 48 h. Antioxidant capacity was reduced at 6 and 8 h (P < 0.05), with the least FRAP value observed at 8 h post-challenge. Antioxidant capacity increased (P < 0.05) again at 10 h, showing similar (P > 0.05) concentrations to those observed at 4 h. By 24 h post-challenge, plasma FRAP values increased (P < 0.05) similar to initial values at -2, 0, and 2 h. It can be inferred that oxidative stress contributes to reduced antioxidant capacity, ultimately interfering with animal growth and productivity. While these values reflect the oxidative stress response to an acute endotoxin challenge, and a subsequent recovery returning to homeostasis within 24 to 48 h, they may also correlate with other physiological and immunological indicators associated with an acute endotoxin challenge.

Sixty-eight (68) crossbred steers were evaluated using two real-time, B-mode ultrasound units to estimate final carcass attributes. The cattle were ultrasounded at the West Texas A&M research feedlot (Canyon, Texas) and carcass data was collected at the West Texas A&M Meats Laboratory (Canyon, Texas) or Tyson Fresh Meats (Amarillo, Texas). Objectives of the study were 1) to compare ultrasound live animal data to carcass attributes at harvest 2) to evaluate the performance differences between the ALOKA 500 (ALK) and the EVO ultrasound units All ultrasound images were captured by the same Ultrasound Guidelines Council (UGC) certified technician with images being processed at the UltraInsights Laboratory (Pierce, Colorado). The correlations between 12th rib fat thickness of the carcass (FTC) and ultrasound (FTU) were 0.84 for the ALK and 0.85 for the EVO, with no differences being found between the two units (P = 0.15). Correlations between the 12-13th rib carcass ribeye area (REAC) and ultrasound ribeye area (REAU) were 0.69 for the ALK and 0.66 for the EVO. There was no difference in REAU size between the two units. Carcass marbling score (MS) and ultrasound intramuscular fat (IMFU) correlations were 0.78 for the ALK and 0.84 for the EVO. The IMF data were found to be different between the two units, with the EVO measuring a mean IMFU value of 6.03 and the ALK a value of 5.26 with the change of 0.77 being different (P < 0.01). It is concluded that both ultrasound units performed favorably when predicting FTC and marbling score but were not highly correlated for REAU. It was found that the predictions between the two units on FT and REA were the same, though the EVO was higher on both. The IMFU values between the ALK and EVO were different, with the EVO again predicting higher values.

Modified-live virus (MLV) vaccines are used routinely to immunize cattle against bovine respiratory disease (BRD) agents, but differences in the route and timing of MLV administration may exist. The objective was to evaluate the safety and efficacy of a parenteral or intranasal MLV administered on d 0 or 28. Three truckload blocks of heifers (initial BW=208 kg; n = 600) were randomly assigned to treatments in a 2×2 factorial. The generalized complete block design consisted of 15 pens/treatment with pen as the experimental unit and 10 animals/pen. Treatments were: 1) Nasalgen 3/Vista BVD CFP on d 0 (NAS0); 2) Vista 5 SQ on d 0 (VIS0); 3) Nasalgen 3/Vista BVD CFP on d 28 (NAS28); 4) Vista 5 SQ on d 28 (VIS28). Performance, activity, and health data were analyzed in a mixed model and a subset of 3 cattle/pen were selected for antibody titer analyses with repeated measures. Body weight and blood samples were collected on d 0, 28, and 56. No differences existed for performance outcomes (P ≥ 0.19). Activity (351.4 vs. 354.3 min/d) and rumination (282.6 vs. 285.4 min/d) time was less (P < 0.01) for delayed vs. arrival vaccinated heifers. A timing × vaccine × day interaction existed (P < 0.01) for IBRV-specific antibody titers such that VIS0 was greatest, NAS0 was intermediate, and VIS28 and NAS28 were least on d 28 (P < 0.01). Percentage of chronically ill cattle was reduced for arrival vs. delayed (1.3 vs. 4.7%; P = 0.02) and tended (P = 0.06) to be less for VIS vs. NAS (1.7 vs. 4.3%). Arrival vaccinated heifers had a reduction in antimicrobial treatment cost (4.63 vs. $7.31; P = 0.02). These data indicate improvement in some health outcomes for the parenteral route and arrival timing of MLV respiratory vaccination but performance was not affected.

Assessment of behavior is a longstanding strategy to assist the diagnosis of clinical bovine respiratory disease (BRD) in beef cattle. Cattle with systemic inflammation caused by infectious pathogen(s) display predictable behavioral adaptations compared to healthy cohorts. Behavioral alterations in BRD-affected cattle include lethargy, social isolation, and anorexia. However, behavior assessment to support BRD case definition in the production setting is challenging because: (1) other bovine diseases cause behavior alterations similar to BRD; (2) cattle have inherent prey instinct to disguise sickness behavior during human evaluation; (3) labor constraints dictate very brief observation of animal behavior; and (4) traditional behavior assessment is subjective and agreement is often poor. Some of these challenges may be overcome with the use of advanced technologies that allow continuous, remote, and objective behavior assessment of individual cattle. Automated methodologies for behavior assessment include three-axis accelerometers that quantify physical behaviors, systems that document feeding/watering behavior, and triangulation systems that document spatial behavior. Each of these behavior-monitoring approaches generates unique information and may facilitate early detection of BRD compared to traditional methods. Nevertheless, adoption of behavior assessment technologies for BRD diagnosis in beef operations hinges upon improved detection, positive return on investment, and successful integration within existing BRD management practices.

To determine the effects of zinc supplementation on the immune response to a combined viral-bacterial respiratory disease challenge, thirty-two beef heifers (255 ± 15 kg) were subjected to a 30-d period of Zn depletion, then randomly assigned to one of three treatment diets fed for 30 d before the challenge: (1) supplementation with 100 mg of Zn from Zn sulfate/kg of DM (Zn100), (2) supplementation with 200 mg of Zn from Zn sulfate/kg of DM (Zn200), and (3) supplementation with 80 mg of Zn/kg of DM from zinc methionine and 20 mg of Zn from Zn sulfate/kg of DM (ZinMet). After the 30-d supplementation period, all heifers were fitted with indwelling vaginal temperature (VT) devices and intra-nasally challenged with 1 × 108 PFU bovine herpesvirus-1 on d -3, and then allowed to rest in outdoor pens for 3 d. On d 0, each heifer was challenged intra-tracheally with an average dose of 2.38 × 107 CFU Mannheimia haemolytica (MH), fitted with an indwelling jugular catheter, and then moved into individual stalls in an environmentally-controlled enclosed barn. Whole blood samples were collected at 1-h (serum) and 2-h (complete blood counts) intervals from 0 to 8 h, and at 12, 24, 36, 48, 60, 72, 168, and 360 h relative to MH challenge. Data were analyzed using the MIXED procedure of SAS specific for repeated measures with fixed effects of treatment, time, and their interaction. There was a treatment effect (p &lt, 0.01) for VT such that Zn200 heifers had greater VT than Zn100 and ZinMet heifers. There was a trend (p = 0.10) for a serum cortisol treatment effect with Zn100 heifers having greater cortisol than ZinMet heifers. Total leukocytes and lymphocytes were greater (p ≤ 0.01) in Zn100 heifers than Zn200 and ZinMet heifers, whereas monocytes were less (p = 0.05) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IL-6 were greater (p = 0.02) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IFN-γ were greater in Zn200 heifers than ZinMet heifers at 0 h, and Zn100 heifers from 0 to 12 h post-MH challenge (treatment x time p = 0.02). Serum haptoglobin was not affected by treatment or treatment x time (p ≥ 0.36) but increased over time (p &lt, 0.01) in all groups. There was a trend (p = 0.11) for ZinMet heifers to have less severe nasal lesion scores than Zn100 heifers. The observed differential physiological responses in this study indicate that zinc source and concentration may alter the response to a bovine respiratory challenge in heifers.

This study evaluated the effects of Sweet Bran™ (SB) and/or wet distillers grains with solubles (WDGS) in the diet alone or in combination on performance, carcass characteristics, ruminal pH, and rumination of finishing beef cattle. Steers (n = 455) were randomly allocated to 48 pens and assigned to 1 of 4 steam-flaked corn-based dietary treatments containing: no byproducts (CON), 20% WDGS (WDGS), 20% SB (SB), or 20% SB and 10% WDGS (COMBO). Within each pen, 2 steers were randomly selected to receive a ruminal pH bolus and ear tag to quantify pH and rumination. Diet samples were collected weekly to determine particle size and physically effective fiber. Final BW, DMI, and ADG were greater (P < 0.01) for WDGS, SB, and COMBO than CON. Hot carcass weight was greatest (P = 0.04) for WDGS and SB, intermediate for COMBO, and least for CON. Yield grade tended (P = 0.09) to be greater for WDGS, SB, and COMBO than CON. A numerical increase in abscessed livers was observed for CON. The percentage of particles > 4 mm was greatest (P < 0.01) for CON, intermediate for SB, and least for WDGS and COMBO. However, NDF (P < 0.01) and peNDF (P < 0.01) were greatest for COMBO, intermediate for WDGS and SB, and least for CON. A treatment × time interaction was observed as CON cattle spent less time ruminating at 0800 and 1000 h (P < 0.01) in a 24h period. Ruminal pH was least (P < 0.01) for CON from 0800 to 1800 h. Addition of WDGS and/or SB improved performance and reduced feed cost of gain when incorporated into steam-flaked corn-based finishing diets. Relationships between peNDF, rumination behavior, and ruminal pH suggest that SB and/or WDGS enhance buffering capacity when steam-flaked corn is replaced in the diet.

The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on serum chemistry, complete blood count, and fecal Salmonella spp. count in high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n = 300) and steers [n = 84; total n = 384; average initial body weight (BW) = 220 ± 16.2 kg] were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. Blood samples were collected from two bulls nearest to the median BW on arrival in each pen (n = 96) and fecal samples were collected from cattle in block 3 (n = 96). The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) negative control (CON); 2) 13 g per animal daily of prepared B. subtilis PB6 product (CST); 3) 450 ppb dry matter (DM) chromium propionate (CHR); and 4) 13 g per animal daily of prepared B. subtilis PB6 product and 450 ppb DM chromium propionate (CST + CHR). Treatments were top dressed in feed bunks daily using 0.45 kg per animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models with repeated measures. Day affected all serum chemistry variables (P ≤ 0.03) except total CO2 (P = 0.34) and all complete blood count variables during receiving (P ≤ 0.02) except percentage basophils (P ≥ 0.12). During the overall receiving period, serum calcium was decreased (P = 0.02) by CHR. Cattle fed CHR had greater total leukocyte count (P = 0.04) and neutrophil count (P = 0.02) during the overall receiving period. Fecal Salmonella spp. count was markedly reduced in cattle fed CST on day 28 (P = 0.01) and overall (P = 0.07). Overall, these data provide metabolic and hematologic insight into the unique challenges presented by lightweight, high-risk feeder cattle. Notably, CST was found to be effective in mitigating fecal enumeration and presumably replication of Salmonella spp. in the gastrointestinal tract.

The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, growth performance, and carcass characteristics of high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n = 300) and steers [n = 84; body weight (BW) = 220 ± 16.2 kg] were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g per animal daily of B. subtilis PB6 (CST); 3) 450 ppb dry matter (DM) chromium propionate (CHR); and 4) 13 g per animal daily of B. subtilis PB6 and 450 ppb DM chromium propionate (CST + CHR). Treatments were top dressed in feed bunks daily using 0.45 kg per animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models. During the receiving period, dry matter intake (DMI) increased (P ≤ 0.03) for CST during each interim period. Overall receiving period daily DMI was 0.35 kg per animal greater for CST (P = 0.01). Cattle fed CST had greater (P ≤ 0.06) BW on days 14, 28, and 56. Likewise, average daily gain (ADG) was improved for CST from day 0 to 14 (P = 0.04) and for the overall receiving period (days 0–56; P = 0.04). From days 0 to 14, CST tended (P = 0.08) to increase gain:feed. During the finishing period, CHR reduced (P = 0.02) final BW and ADG (day 56 to final; P = 0.01) and ADG was less for CHR over the entire feeding period (day 0 to final; P = 0.03). The main effect of both CST (P = 0.02) and CHR (P = 0.03) decreased the overall treatment rate for bovine respiratory disease (BRD), and CST reduced overall antimicrobial treatment cost by $3.50 per animal compared to CON (P = 0.03). Hot carcass weight (HCW) decreased (P = 0.01) in cattle fed CHR. The percentage of edible livers tended to increase (CST × CHR; P = 0.08) in the CST treatment. Feed intake and growth performance outcomes during the receiving period were improved by CST but not CHR supplementation. However, both CST and CHR supplementation decreased the BRD morbidity rate. During the finishing period, performance and HCW were reduced in cattle supplemented with CHR.

The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, growth performance, and carcass characteristics of high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n = 300) and steers [n = 84; body weight (BW) = 220 ± 16.2 kg] were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g per animal daily of B. subtilis PB6 (CST); 3) 450 ppb dry matter (DM) chromium propionate (CHR); and 4) 13 g per animal daily of B. subtilis PB6 and 450 ppb DM chromium propionate (CST + CHR). Treatments were top dressed in feed bunks daily using 0.45 kg per animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models. During the receiving period, dry matter intake (DMI) increased (P ≤ 0.03) for CST during each interim period. Overall receiving period daily DMI was 0.35 kg per animal greater for CST (P = 0.01). Cattle fed CST had greater (P ≤ 0.06) BW on days 14, 28, and 56. Likewise, average daily gain (ADG) was improved for CST from day 0 to 14 (P = 0.04) and for the overall receiving period (days 0–56; P = 0.04). From days 0 to 14, CST tended (P = 0.08) to increase gain:feed. During the finishing period, CHR reduced (P = 0.02) final BW and ADG (day 56 to final; P = 0.01) and ADG was less for CHR over the entire feeding period (day 0 to final; P = 0.03). The main effect of both CST (P = 0.02) and CHR (P = 0.03) decreased the overall treatment rate for bovine respiratory disease (BRD), and CST reduced overall antimicrobial treatment cost by $3.50 per animal compared to CON (P = 0.03). Hot carcass weight (HCW) decreased (P = 0.01) in cattle fed CHR. The percentage of edible livers tended to increase (CST × CHR; P = 0.08) in the CST treatment. Feed intake and growth performance outcomes during the receiving period were improved by CST but not CHR supplementation. However, both CST and CHR supplementation decreased the BRD morbidity rate. During the finishing period, performance and HCW were reduced in cattle supplemented with CHR.

The study objective was to determine if a combined weaning and transportation stress model affected performance, antibody, endocrine, or hematological responses to modified-live virus (MLV) or killed virus (KV) respiratory vaccination in beef steers. In total, 48 calves (Day 0 BW = 226 &plusmn, 6.2 kg) from a single origin were used in a 2 &times, 2 factorial to evaluate main effects of stress model, vaccine type, and their interaction, resulting in four treatments (n = 12/treatment) including non-stress control (C) with KV (CKV), C with MLV (CMLV), stress model implementation (S) with KV (SKV), and S with MLV (SMLV). The C calves were weaned at the origin ranch on Day &minus, 37 and transported 472 km to the study site on Day &minus, 21 to allow acclimation. The S calves were weaned on Day &minus, 3, transported 460 km to a research facility on Day &minus, 2, held overnight, and transported 164 km to the study site on Day &minus, 1 to mimic the beef cattle marketing process. Vaccines were administered on Day 0 and KV was revaccinated on Day 14. The animal was the experimental unit and dependent variables were analyzed using PROC MIXED with repeated measures (day). A stress model effect (p = 0.01) existed for DMI from Day 0 to Day 7 with greater DMI for C (6.19 vs. 4.64 kg/day) when compared to S. The MLV groups had reduced (p = 0.05) ADG from Day 0 to Day 56, compared to KV. There was a vaccine type &times, day (p &lt, 0.01) interaction with increased (p &le, 0.01) PI3V- and IBRV-specific antibody titers for KV on Day 21, conversely, MLV had increased (p &le, 0.01) BVDV titers on Days 14, 28, 35, 42, 49, and 56. Increased (p &le, 0.05) BRSV titers were observed in a stress model &times, 0.01) interaction for S on Days 21, 28, 36, and 42, however, C exceeded S in BVDV-specific antibody concentration on Days 21, 28, and 49. A day effect (p &lt, 0.01) was observed for serum haptoglobin with the greatest (p &lt, 0.01) concentration on Day 3. Serum cortisol concentration was greater (p &le, 0.04) for C vs. S on Days &minus, 2, 0, 1, 3, and 5. Total leukocytes were decreased for C vs. S on Days 0, 1, 3, 5, 7, 14, and 21 (p &le, 0.02). A reduction (p &le, 0.04) in total leukocytes was observed for MLV on Days 5, 7, and 14 vs. KV. Neutrophils and neutrophil:lymphocyte were markedly increased (p &le, 0.01) for S on Day &minus, 2, whereas neutrophils were decreased (p &le, 0.01) on Days 1 and 21 for S. Monocytes were decreased on Days 1, 5 and 7 for MLV (p &le, 0.04) and Days &minus, 2 to 14 for S (p &le, 0.03). Eosinophils were reduced (p = 0.007) for S vs. C on Day &minus, 2, yet a distinct rebound response (p = 0.03) was noted for S on Day 0. The results indicate that S and MLV vaccination more profoundly induced immunomodulation in beef calves.

Objectives of this experiment were to examine the effects of live yeast (LY) supplementation on immunological, physiological, and behavioral responses in steers experimentally challenged with Mannheimia haemolytica (MH). Thirty-six crossbred Angus steers (BW = 352 ± 23 kg) seronegative for MH were allocated within a 2 × 2 factorial arrangement: Factor 1 = roughage-based diet with LY (Saccharomyces cerevisiae boulardii CNCM I-1079, 25 g·per steer daily) or negative control (CON). Factor 2 = bronchoselective endoscopic inoculation with MH or phosphate buffer solution (PBS). Steers were fed their respective diets for 28 d prior to MH challenge on day 0. Reticulo-rumen temperature (RUT; ThermoBolus, Medria) was measured continuously at 5-min intervals and rectal temperature on days -4, 0, 1, 2, 3, 5, 7, 10, and 14 relative to MH inoculation. Compared with PBS-treated steers, the steers inoculated with MH had increased (P 41 °C) 9 to 11 h post-MH challenge, whereas rectal temperature was increased (P < 0.04) in MH-inoculated steers on day 1 post-MH challenge. Supplementation with LY increased (P < 0.05) rectal temperature on days 0, 7, and 10, relative to CON steers. There were inoculation x day interactions (P < 0.01) for lymphocyte, neutrophil, leukocyte, and haptoglobin concentrations. Steers challenged with MH had increased (P < 0.05) neutrophil concentration from days 1 to 3, leukocyte concentration on days 1 and 2 and haptoglobin concentration on days 1 to 5 post-MH challenge compared with PBS-treated steers. Steers supplemented with LY exhibited increased (P < 0.02) cortisol throughout the study compared with the CON treatment. Following inoculation, MH-challenged steers exhibited reduced (P < 0.05) DMI, eating rate, frequency, and duration of bunk visit (BV) events compared with PBS-treated steers. Results from this study demonstrate that the experimental challenge model effectively stimulated acute-immune responses and behavioral changes that are synonymous with naturally occurring bovine respiratory disease (BRD). However, supplementation with LY minimally altered the impact of the MH challenge on physiological and behavioral responses in this study. Continuously measured RUT was more sensitive at detecting febrile responses to MH challenge than rectal temperature. These results serve to guide future research on behavioral and physiological alterations exhibited during a BRD infection.

One hundred and eighty beef bulls (BW = 337 ± 10.9 kg) were blocked by BW (6 blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood-restrictive rubber band placed upon the dorsal aspect of the scrotum, and 3) BUL; bulls with testicles remaining intact. Cattle were grouped by weight block in a randomized complete block design (three treatment pens/block and 10 cattle/pen) and harvested by block on three separate dates when blocks reached similar BW and visual subcutaneous fat thickness depth. Striploins were removed from the left carcass sides, vacuum packaged and aged for 14 d, and then frozen at −20 °C. Frozen striploins were sliced into 2.54-cm-thick steaks and remained frozen until analyses. Steaks (n = 3/animal) were used to assess consumer acceptability via consumer taste panel (n = 152 panelists), Warner-Bratzler shear force, percentage cook loss, and cooked color values. Data were analyzed using mixed model procedures; pen was the experimental unit for all dependent variables. Hot carcass weights and LM area were greater (P < 0.01) for the INJ and BUL treatments compared with BAN. Mean yield grade did not differ between treatments (P = 0.12), although BAN carcasses had smaller LM area (P < 0.01) than BUL or INJ carcasses. Percentage of USDA Choice or better carcasses was greater (P < 0.01) for BAN than INJ and BUL treatments. Consumer panelists detected a difference in perceived tenderness; BAN steaks had greater (P = 0.02) tenderness scores than BUL steaks, whereas INJ steaks were intermediate. Panelists rated juiciness of BAN steaks greater (P < 0.01) than either BUL or INJ steaks. Panelists rated beef flavor greater (P = 0.01) for BAN and BUL steaks than INJ steaks. Overall acceptability was greater (P < 0.01) for BAN compared with INJ steaks, whereas BUL steaks were intermediate. Percentage cook loss of striploin steaks (P = 0.47) and Warner-Bratzler shear force values (P = 0.11) did not differ. Cooked color lightness (L*) and redness (a*) values were not affected (P ≥ 0.23) by treatment. Striploin steaks from BAN and BUL treatments had greater (P = 0.02) yellowness values (b*) than INJ steaks. The ratio of red-to-brown (630:580 nm) of cooked striploin steaks was greater (P = 0.05) for INJ than either BAN or BUL treatments. Carcass and palatability outcomes of INJ were more similar to BUL than BAN, suggesting limited efficacy of INJ in mature beef bulls at feedlot entry.

The objective of this study was to evaluate a combination of best management practices strategy for steer calves grazing tall fescue pastures with a range of toxicity. The experiment was conducted over 2 grazing seasons (fall 2015 for 91 d and spring 2016 for 84 d). Steers (n = 80 within season, body weight [BW] = 197.0 ± 15.43 kg [fall] and 116.9 ± 4.88 [spring]) were stocked at 2.45 and 4.1 calves/ha in fall and spring, respectively, to 16 pastures with varying levels of toxicity based on interim ergovaline (EV) concentration within season. Pastures were assigned to either mineral (MIN, n = 8) only management (MGMT) or a cumulative MGMT (CM, n = 8). The CM treatment included an implant containing 40-mg trenbolone acetate, 8-mg estradiol, and 29-mg tylosin tartrate (Component TE-G with Tylan, Elanco Animal Health, Greenfield, IN), 150 mg/calf daily monensin (Elanco Animal Health), and 1% BW of a 50:50 corn gluten feed:soybean hull supplement (as-is basis). Data were analyzed within season using pasture as the experimental unit. For fall and spring, the EV concentration was 1,476 ± 883.2 and 1,173 ± 620.6 ppb, respectively, and ranged from 90 to 2,180 ppb. During the fall, forage allowance did not differ (P = 0.76) between CM and MIN. In the spring, however, forage allowance only differed for the month of June (P ≤ 0.05, 2.55 vs. 3.22 ± 0.177 kg DM/kg BW, for MIN and CM, respectively). In the fall, average daily gain (ADG) responded to the simple effects of EV (P = 0.01) and MGMT (P < 0.001), and ADG for MIN steers was explained by ADG = 0.41 - 0.000064 × EV, whereas ADG for CM was explained by ADG = 1.05 - 0.000064 × EV. In the spring, there was an EV × MGMT interaction (P = 0.03) for ADG. For MIN, ADG = 0.80 - 0.000278 × EV, whereas for CM, ADG = 0.94 + 0.000001835 × EV. In spring, the ADG response to CM relative to MIN increased as EV increased. The CM strategy resulted in lower blood urea nitrogen than MIN in fall and spring (P < 0.01), but prolactin and serum Cu were not affected by MGMT in either season. In conclusion, performance was improved within the fescue belt by implementing feeding strategies using implants, ionophores, and supplementation, but a detailed economic analysis is warranted. Further research is needed to evaluate CM programs under varied stocking rates and in combination with dilution of endophyte-infected fescue pastures with nontoxic grasses or legumes.

For decades, we have relied upon visual observation of animal behavior to define clinical disease, assist in breeding selection, and predict growth performance. Limitations of visual monitoring of cattle behavior include training of personnel, subjectivity, and brevity. In addition, extensive time and labor is required to visually monitor behavior in large numbers of animals, and the prey instinct of cattle to disguise abnormal behaviors in the presence of a human evaluator is problematic. More recently, cattle behavior has been quantified objectively and continuously using advanced technologies to assess animal welfare, indicate lameness or disease, and detect estrus in both production and research settings. The current review will summarize three methodologies for quantification of cattle behavior with focus on U.S. beef production systems; 1) three-axis accelerometers that quantify physical behavior, 2) systems that document feeding and watering behavior via radio frequency, and 3) triangulation or global positioning systems to determine location and movement of cattle within a pen or pasture. Furthermore, advances in Wi-Fi and radio frequency technology have allowed many of these systems to operate remotely and in real-time and efforts are underway to develop commercial applications that may allow early detection of respiratory or other cattle diseases in the production environment. Current challenges with commercial application of technology for early disease detection include establishment of an appropriate algorithm to ensure maximum sensitivity and specificity, reliable and repeatable data collection in harsh environments, cost:benefit, and integration with traditional methodology for clinical diagnosis. Advanced technologies have also allowed cattle researchers to determine temporal variance in behavior or variability between experimental treatments. However, these data sets are typically very large and challenges exist regarding statistical analysis and reporting.