Bovine respiratory disease (BRD), as one of the most common and costly diseases in the beef cattle industry, has significant adverse impacts on global food security and the economic stability of the ...industry. The bovine respiratory microbiome is strongly associated with health and disease and may provide insights for alternative therapy when treating BRD. The niche-specific microbiome communities that colonize the inter-surface of the upper and the lower respiratory tract consist of a dynamic and complex ecological system. The correlation between the disequilibrium in the respiratory ecosystem and BRD has become a hot research topic. Hence, we summarize the pathogenesis and clinical signs of BRD and the alteration of the respiratory microbiota. Current research techniques and the biogeography of the microbiome in the healthy respiratory tract are also reviewed. We discuss the process of resident microbiota and pathogen colonization as well as the host immune response. Although associations between the microbiota and BRD have been revealed to some extent, interpreting the development of BRD in relation to respiratory microbial dysbiosis will likely be the direction for upcoming studies, which will allow us to better understand the importance of the airway microbiome and its contributions to animal health and performance.
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.
Despite research and increased availability of antimicrobials, the prevalence and challenges associated with BRD in stocker and feedlot operations remain. Preconditioned calves can better handle the ...transition from the origin ranch to the feedlot, yet there is incentive for buyers to purchase high-risk cattle at a reduced cost, and this is influenced by the proven efficacy and availability of antimicrobial metaphylaxis. The poor sensitivity of current BRD field diagnostic methods, typical pathogenesis of BRD, and labor issues are additional reasons to use metaphylaxis. Nevertheless, practitioners should consider comprehensive and novel approaches to judiciously guide decisions on metaphylactic use of antimicrobials.
Abstract
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.
High-risk cattle may not require a low-energy receiving diet containing high proportions of roughage upon arrival to the feedlot.
Lay Summary
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.
The objectives of this study were to evaluate the impacts of two modified-live virus (MLV) vaccination protocols and respiratory disease (BRD) occurrence on the microbial community composition of the ...nasopharynx in feedlot cattle.
The treatment groups included in this randomized controlled trial included: 1) no viral respiratory vaccination (CON), 2) intranasal, trivalent, MLV respiratory vaccine in addition to a parenteral BVDV type I and II vaccine (INT), and 3) parenteral, pentavalent, MLV respiratory vaccination against the same agents (INJ). Calves (
= 525) arrived in 5 truckload blocks and were stratified by body weight, sex, and presence of a pre-existing identification ear-tag. A total of 600 nasal swab samples were selected for DNA extraction and subsequent 16S rRNA gene sequencing to characterize the microbiome of the upper respiratory tract. Nasal swabs collected on d 28 from healthy cattle were used to evaluate the impact of vaccination on upper respiratory tract (URT) microbial communities.
Firmicutes were less abundant in INT calves (
= 114;
< 0.05) and this difference was attributed to decreased relative abundance (RA) of
. (
= 0.04).
and
had lower RA in INT (
< 0.05). The microbiome in healthy animals on d 28 had increased Proteobacteria (largely
spp.) and decreased Firmicutes (comprised almost exclusively of
) compared to animals that were treated for or died from BRD (
< 0.05). Cattle that died had a greater RA of
. in their respiratory microbiome on d 0 (
< 0.02). Richness was similar on d 0 and 28, but diversity increased for all animals on d 28 (
>0.05).
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 (P < 0.01). There was a treatment × time interaction (P < 0.01) for Hs detection; on days 14 and 28, INT (21.1% and 57.1%) were more frequently (P < 0.01) 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 (P < 0.01); 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.
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.
Abstract
Auction-derived steers (n = 36; initial BW = 284 ± 11 kg) were received to compare performance, rumination characteristics, and rumen pH differences due to alternative ration energy ...densities and feed management strategies during a 56 d receiving study. Cattle were weighed on day -1 and randomized to 1 of 3 treatments. Time spent ruminating was quantified with a three-axis accelerometer ear-tag. Rumen pH and temperature were logged in a random subset (n = 6 per treatment) by a ruminal bolus. Cattle were processed identically and housed in individual pens. The modified-live virus respiratory vaccination was delayed until day 28. The finisher (FIN) cattle were provided their daily feed as a high energy density (1.39 Mcal NEg/kg) diet. The finisher + hay (FIN+H) cattle were provided the same diet but were also offered 0.5% BW DM as coastal Bermudagrass hay on days 1, 4, 7, 10, 13, 16, 19, 22, 25, and 28. The control (CON) cattle were fed a low energy density (0.93 Mcal NEg/kg) diet from day 0 to 7, then transitioned to the FIN diet by replacing an additional 25% of the daily feed call with FIN every 7 d until 100% of the diet was FIN on day 29. Feed offering for CON was increased more aggressively (0.45 kg DM daily for days 1 to 7, every other day for day 8 to 14) than FIN and FIN+H (0.45 kg DM every other day for days 1 to 7, daily for days 8 to 14). Performance and DMI were analyzed using PROC MIXED in SAS with treatment as a fixed effect. Rumination, pH, and temperature models included repeated measures. There was no treatment difference observed for BW, average daily gain (ADG), or G:F (P ≥ 0.12). There was a treatment × day interaction (P = 0.06) for rumen temperature, where FIN increased more rapidly following vaccination on day 28 compared to CON (P ≤ 0.04). Daily rumination minutes were greater (P < 0.01) for CON than FIN from days 7 to 22. Additionally, CON had the greatest (P < 0.01) hourly rumination from 2000 to 0800 hours. Lower minimum daily rumen pH occurred in FIN+H (P ≤ 0.06) on weeks 1, 2 and 6 to 8 compared to CON. There were minimal statistical differences in area under the curve or time below pH thresholds, probably due to large animal-to-animal variation. Hourly rumen pH was reduced (P ≤ 0.05) for FIN vs. FIN+H and CON during the initial 28 d, but greater (P = 0.05) for FIN and FIN+H during the final 28 d. When cattle are individually fed, greater energy density rations can be fed initially without compromising performance, but this needs to be evaluated in group pens where greater DMI variation is probable.
Abstract
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.
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 (
= 30) and cattle (
= 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 (
< 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
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.
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.
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