Search

Fluoroquinolones are a class of antimicrobial commonly used in human medicine, and deemed critical by the World Health Organization. Nonetheless, two formulations are approved for the treatment of respiratory disease in beef cattle. The objective of this study was to determine the gastrointestinal pharmacokinetics and impact on enteric bacteria of cattle when receiving one of the two dosing regimens (high: 40 mg/kg SC once or low: 20 mg/kg IM q48hr) of danofloxacin, a commonly utilized synthetic fluoroquinolone in veterinary medicine. Danofloxacin was administered to 12 steers (age 7 months) fitted with intestinal ultrafiltration devices at two different dosing regimens to assess the gastrointestinal pharmacokinetics, the shifts in the gastrointestinal microbiome and the development of resistant bacterial isolates. Our results demonstrated high intestinal penetration of danofloxacin for both dosing groups, as well as, significant differences in MIC values for E. coli and Enterococcus between dosing groups at selected time points over a 38 day period. Danofloxacin treatment consistently resulted in the Euryarchaeota phyla decreasing over time, specifically due to a decrease in Methanobrevibacter. Although microbiome differences were minor between dosing groups, the low dose group had a higher number of isolates with MIC values high enough to cause clinically relevant resistance. This information would help guide veterinarians as to appropriate dosing schemes to minimize the spread of antimicrobial resistance. [ABSTRACT FROM AUTHOR]

Background: Severity of lung lesions quantified by thoracic ultrasonography (TUS) at time of bronchopneumonia (BP) diagnosis predicted death among steers not treated for this condition. Further research is needed to confirm that lung lesions detected by TUS can be associated with negative outcomes in cattle with BP that subsequently were treated. Objective: To quantify the effects on relapse rate and average daily gain (ADG) of lung lesions detected by TUS at first BP diagnosis in feedlot cattle. Animals: Prospective cohort of mixed beef‐breed steers (n = 93; 243 ± 36 kg) and heifers (n = 51; 227 ± 42 kg) with BP at 4 feedlots. Methods: Thoracic ultrasonography was performed by the same clinician and 16‐second TUS videos were evaluated offline for maximal depth and area of lung consolidation, maximum number of comet tails, and maximal depth of pleural fluid. Individual ADG was calculated between 1 and 120 days after arrival. Effects of lesions on relapse rate and ADG were investigated using mixed regression models. Results: Maximal depth of lung consolidation was associated with a higher risk of relapse (odds ratio [OR], 1.337/cm; 95% confidence interval [CI], 1.042‐1.714) and lower ADG (− 34 g/cm; −64 to −4). Maximal area of lung consolidation also was associated with a higher relapse risk (OR, 1.052/cm2; 1.009‐1.097) but not with ADG. Comet tails and pleural fluid were not associated with risk of relapse or ADG. Conclusions and Clinical Importance: Quantifying maximal depth and area of lung consolidation by TUS at first BP diagnosis can provide useful prognostic information in feedlot cattle. [ABSTRACT FROM AUTHOR]

Highlights • The duration of lameness was not associated with diagnosis of septic arthritis of the distal interphalangeal joint (DIJ). • The presence of a lameness score of ≥4 increased the probability of septic arthritis of the DIJ by 85.7%. • The presence of asymmetric swelling at the coronary band was closely associated with septic arthritis of the DIJ. Abstract Lameness in cattle is a welfare concern and is associated with important economic losses in beef cattle operations. Infection of the distal interphalangeal joint (DIJ) results in severe lameness and if left untreated carries a poor prognosis. Diagnosis of DIJ infection is challenging in the field. The aim of this study was to determine factors associated with septic arthritis of the DIJ in beef cattle. Thirty-nine beef cattle with a complaint of single-foot lameness were used in this study. History and lameness examination data were recorded and analyzed. Radiographic changes and cytology of synovial fluid of the affected DIJ were used to define the presence (cases) or absence (controls) of DIJ infection. Asymmetric swelling at the coronary band of the affected foot and a lameness score of ≥4/5 significantly increased the odds (odds ratio [OR] = 63.2 and OR = 120, respectively) of diagnosis of septic arthritis of the DIJ in beef cattle with a single-foot lameness compared to cattle with no asymmetry of the coronary band or lameness scores <3. Routine lameness examination findings could be used in the field to rapidly recognize infection of the DIJ in lame beef cattle. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper was to present the first report of Prosopis nigra poisoning of cattle in Argentina. Outbreaks occurred in five farms located in Salta and Santiago del Estero provinces. All animals were examined, euthanized and necropsied. Clinical signs included tongue protrusion, twitches and tremors of muscles of mastication, weight loss and lethargy. Severe atrophy of the masseter, buccinator and lingual muscles was observed, along with neuronal vacuolation in the nuclei of the trigeminal, facial, and hypoglossus nerves. These findings and the clinical signs are consistent with results obtained in animals, spontaneously and experimentally intoxicated with Prosopis juliflora in previous studies. Several species of this genus are native to Argentina. Farmers should be warned about the suspected toxicity by Prosopis nigra , since this species has wide geographical distribution in the country. Highlights • First report providing local information on outbreaks of poisoning by P. nigra pods in cattle. • The macroscopic and microscopic findings were consistent with those observed in poisoning by other Prosopis species. • P. nigra has wide geographical distribution in the Argentina, Paraguay, Brazil and Uruguay region. [ABSTRACT FROM AUTHOR]

Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle. Respiratory viral infections are key components in predisposing cattle to the development of this disease, which allow secondary bacterial infection and disease development. This study was designed to investigate the prevalence of bovine respiratory disease complex in beef farms at Alexandria and Elbehera Governorates. Six beef farms have 3230 fattenin11g calves 6-12 months age were clinically examined for respiratory disease complex. 971 animals were having respiratory signs at a percentage of 30% with variable prevalence in the 6 farms. Deep nasal swabs were collected from diseased animals and investigated for Bovine herpesvirus type one (BHV-1) by conventional polymerase chain reaction (PCR) and for bacteriological examination. PCR could detect BHV-1 infection in 3 samples out of 40 samples examined and the main bacteria isolated from diseased animals were Pasteurella multocida and Pseudomonas aerugeinosa. In conclusion, Bovine herpesvirus type one is one of the major pathogens causing respiratory signs in beef cattle and predispose cattle to bovine respiratory disease complex. And pastuerella multocida is secondary bacterial invader which cause the disease. The role of pseudomonas aeruginosa as a causes of respiratory diseases needs further studies. [ABSTRACT FROM AUTHOR]

Actinobacillosis usually is a sporadic infection that affects the tongue in cattle ("wooden tongue") with possible spread to the digestive tract. Two 4‐year‐old Rouge‐des‐Prés cows from a single French beef herd were referred for chronic (2‐6 months) swelling and cutaneous nodules in the distal hind limbs. In addition to cutaneous signs, physical examination disclosed cachexia, lameness, lymphadenitis of the hind limbs, and pneumonia in both cows. Cytologic examination of direct skin smears was inconclusive, and no parasites were observed in examination of multiple skin scrapings. Histopathological examination of skin and lung biopsy specimens identified chronic, diffuse, severe pyogranulomatous dermatitis, associated with Splendore‐Hoeppli phenomenon and intralesional Gram‐negative bacteria. Cultures from skin, lymph nodes, and lungs (both cows were euthanized for welfare reasons) identified a Pasteurellaceae organism, confirmed as Actinobacillus lignieresii by partial sequencing of the rpoB gene. This report emphasizes that actinobacillosis can appear as a small outbreak in cattle with cutaneous and respiratory signs. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the effects of treatment with different anthelmintic compounds on the productivity of naturally infected calves and the economic viability of these treatments within extensive breeding systems employing different nutritional strategies after weaning. For this purpose, 4 farms with 42-60 calves naturally infected with gastrointestinal nematodes were selected. The calves were distributed into 6 groups (7-10 animals each) per farm and treated with ivermectin 1%, ivermectin 3.15%, eprinomectin 5%, levamisole 7.5%, albendazole 15%, and control group (no treatment). These animals were evaluated over an experimental period of 150 days. Levamisole 7.5% presented the best capacity for the reduction of eggs per gram (EPG) of feces in all herds evaluated, followed by albendazole 15% and eprinomectin 5%. Parasite resistance to multiple drugs was found in all herds, especially those of Cooperia, Haemonchus, Oesophagostomum, and Trichostrongylus. For farm 1, differences in weight gain and EPG reduction percentages led to a difference of US$285.06 between the levamisole and ivermectin 3.15% groups. Similar findings were noted for the levamisole and ivermectin 1% groups of farm 3, with a difference of US$399.37 because of the final weight gain in these groups. For farms 2 and 4, the ivermectin 3.15% and control groups, respectively, were the most profitable; these unexpected results were possibly influenced by variables not measured during the experimental period. This study suggested that anthelmintic treatments should always precede an efficacy test, once they are demonstrated to be most profitable under adequate breeding conditions, to ensure adequate control of gastrointestinal nematode infection. [ABSTRACT FROM AUTHOR]

Foreign animal diseases can cause severe and lasting economic impacts to producers, directly and indirectly. Understanding producer investment cost structures can provide industry and policy makers better tools to encourage biosecurity adoption. Consistent with the literature, many factors can contribute to an individual operator's decision to invest in biosecurity based on individual characteristics, perception of disease likelihood, or expected losses associated with a disease event. We used a producer survey and a one‐and‐one‐half bound econometric model to estimate feedlot operator willingness to pay to invest in disposal capacity within the next 3 years. Results indicate an average willingness to pay of $14,310 for a one‐time investment in on‐farm disposal capacity to address carcass movement restrictions during a disease outbreak. We found several factors that contribute to and explain the heterogeneity between feedlots and their adoption decisions. Primarily, size of the feedlot and death loss rate significantly impact adoption, which both potentially speak to the financial liquidity and investment potential of a feedlot enterprise. While there is no failsafe in disease prevention, these results provide a better understanding for how to study and structure policy and cost structures to incentivize adoption of biosecurity. [ABSTRACT FROM AUTHOR]

Abstract This cross-sectional study aimed to assess in post-mortem the prevalence of specific claw disorders and their location on the sole in hind feet of finishing beef cattle reared indoors under intensive production systems. Evaluation was made on animals that were introduced in the ordinary slaughterhouse planning, presumably with no signs of impaired locomotion or severe lameness. A total of 4292 hind feet (right and left) belonging to 153 batches were collected (average feet/batch 28.1 ± 5.62 (SD)) in 3 abattoirs in Northern Italy at 3 time points (April-June and September-October 2016; February–March 2017). One veterinarian performed the claw trimming first and then scored the presence of specific claw disorders and their position on the sole considering 7 zones (in the digital and interdigital areas). All claw disorders in a specific zone were recorded as binary (presence/absence). Infectious (ILS), non-infectious (NILS), and global (GLS) scores were calculated considering both the type of claw disorder detected and the number of zones affected. Non-infectious disorders were the most common diagnoses among batches, mainly on the lateral claws and in the heel-sole junction area. In particular, white line abscesses and ulcers (sole and toe ulcers) were also found as two of the most debilitating and painful lesions with a non-negligible frequency. Infectious diseases, when occurring in a batch, spread to almost all feet. As expected, GLS distribution on the total feet inspected showed a non-harmful condition, given that the worst scores from 3 to 13 were assigned to a restricted sample of feet (15%) and were far from the maximum potential value of 50. However, the GLS of all batches monitored revealed 10 critical batches having no healthy feet or more than 50% of feet graded with the worst scores. Since right and left feet of the same animal showed similar clinical diagnoses, a more efficient claw health evaluation system should consider only one foot. Although all cattle inspected were supposed to have no evident locomotory problems before slaughter, the detection of several foot disorders and the considerable distribution in some batches might suggest poor conditions on farms affecting finishing beef cattle health, behaviour, and welfare. It is therefore advisable that possible predisposing factors of specific claw disorders on the farms of origin be investigated more deeply. [ABSTRACT FROM AUTHOR]

Abstract The venereal diseases bovine trichomoniasis (BT) and bovine genital campylobacteriosis (BGC) cause economic losses in endemic areas like La Pampa province in Argentina, where beef cattle are usually managed extensively. The eradication of both diseases is a priority in Argentine. The aim of this case-control study was to identify shared and specific risk factors of both diseases from the data obtained from the Provincial Program for the Control and Eradication of BT and BGC in La Pampa (PCE). The study population included 5777 breeding beef herds tested for BT and BGC in 2013. The study comprised 3481 herds that were surveyed in situ by official PCE veterinarians, distributed as follows: 3159 negative herds (with no BT or BGC positive bulls), 121 BT case herds (with at least a BT positive bull), 170 BGC case herds (with at least a BGC positive bull) and 31 BT and BGC co-infected case herds (with at least a positive bull for each disease). Three multivariable analyses were performed in order to identify the risk factors using a logistic regression model. Results showed that the risk factors shared by both diseases were the number of bulls (OR for BT = 1.03, 95% CI: 1.02–1.04, p < 0.001; OR for BGC = 1.02, 95% CI: 1.01–1.03, p < 0.001; OR for BT and BGC co-infection = 1.02, 95% CI: 1.01–1.04, p = 0.003) and the presence in the previous year of each disease (OR for BT = 18.69, 95% CI: 11.82–29.57, p < 0.001; OR for BGC = 4.65, 95% CI: 3.18–6.81, p < 0.001; OR for BT and BGC co-infection = 39.18, 95% CI: 16.72–91.80, p < 0.001). Disease-specific risk factors were continuous breeding season for BT (OR = 1.59, 95% CI: 1.04–2.47, p = 0.034), and inadequate condition of the fences for BGC (OR = 1.51, 95% CI: 1.06–2.15, p = 0.022). An integrated approach to venereal disease management needs to consider the risk characteristics identified in this study. This could lead to reduce both diseases and improve the efficiency of BT and BGC control activities in La Pampa. [ABSTRACT FROM AUTHOR]

Summary: Bovine respiratory disease (BRD) is a complex disease that is associated with infection by bacterial and viral pathogens when cattle fail to adequately respond to stress. The objective of this study was to use gene set enrichment analysis of SNP data (GSEA‐SNP) and a network analysis (ingenuity pathway analysis) to identify gene sets, genes within gene sets (leading‐edge genes) and upstream regulators associated with BRD in pre‐weaned dairy calves and beef feedlot cattle. BRD cases and controls were diagnosed using the McGuirk health scoring system. Holstein calves were sampled from commercial calf‐raising facilities in California (1003 cases and 1011 controls) and New Mexico (376 cases and 372 controls). Commercial feedlot cattle were sampled from Colorado (500 cases and 499 controls) and Washington (504 cases and 497 controls). There were 102 and 237 unique leading‐edge genes identified in the dairy calf and beef cattle populations respectively. Six leading‐edge genes (ADIPOQ, HTR2A, MIF, PDE6G, PRDX3 and SNCA) were associated with BRD in both dairy and beef cattle. Network analysis identified glucose as the most influential upstream regulator in dairy cattle, whereas in beef cattle, TNF was the most influential upstream regulator. The genes, gene sets and upstream regulators associated with BRD have common functions associated with immunity, inflammation and pulmonary disease and provide insights into the mechanisms that are critical to BRD susceptibility in cattle. [ABSTRACT FROM AUTHOR]

Highlights • Three groups of beef steer calves (n = 120) were sampled at three time points. • The bacterial microbiota of the nasopharynx was characterized (16S rRNA). • Nasopharyngeal bacterial microbiota evolved over time in all calf groups. • Patterns of microbiota evolution differed across all time points and calf groups. • Mycoplasma was the most abundant genus and M. dispar was the most abundant species. Abstract The composition of the nasopharyngeal bacterial microbiota has been shown to play a role in cattle respiratory health. However, previous studies are narrow in scope regarding longitudinal observations, limiting our understanding of how respiratory bacteria evolve over time. The objective was therefore to characterize this microbiota and its evolution over time in beef calves. A total of 120 crossbred beef-breed steer calves were enrolled in a study in southern Alberta at the time of first vaccination (spring processing), comprising three groups (40 calves/group) that originated from different ranches and were placed in different feedlots. Deep nasopharyngeal swab samples were collected from the calves at the time of spring processing, arrival at the feedlot, and a targeted 40 days after feedlot arrival. The swabs were processed for DNA extraction and the V4 region of the 16S rRNA gene was sequenced to evaluate the microbiota. The composition of the microbiota differed among groups of calves, with each group showing different relative abundances of 963 observed sequence variants. Mycoplasma was the most abundant genus and M. dispar the most abundant species across all groups. There was a distinct shift in the composition of the microbiota over time for all calf groups; however, changes in sequence variants differed by group. Variations in both microbiota composition and temporal changes of sequence variants according to calf group indicates that the respiratory microbiota of beef cattle may lack a common pattern of evolution from ranch to feedlot, and that future studies should account for potential group effects. [ABSTRACT FROM AUTHOR]

Abstract Parameterizing mathematical models of foot-and-mouth disease virus (FMDv) transmission is challenging due to knowledge gaps on the variable dynamics in susceptible populations. Expert opinion surveys are an approach to gather data on topics where no data have been reported. The objective of this study was to collect—via an expert-opinion survey—key parameter values of the potential FMD natural history and transmissibility in beef feedlot cattle in the U.S. Experts with experience working with FMD in endemic and non-endemic settings were targeted. Parameters surveyed were: duration of infection and disease stages, proportions of animals with specific clinical manifestations, duration and extent of the reduction in feed consumption, and probabilities of severe clinical disease and FMDv transmission. We surveyed the parameter values for infections by strains of different virulence, different infection doses, and routes of transmission. Twenty-seven experts from around the world agreed to participate and 16 (59%) completed the survey. The expert responses to individual questions were resampled via Monte Carlo simulations; to the resulting distributions, candidate theoretical distributions were fitted using the maximum likelihood method and the sought parameter values estimated based on the best-fit distributions. Of the infection stages, the estimates of the expected FMD latent period in beef feedlot ranged from 1.7 to 5.3 days and the infectious period from 5.6 to 10.9 days. Of the disease stages, the estimated incubation period ranged from 2.9 to 6.1 days, subclinical period from 1.2 to 2.8 days, and clinical period from 4.2 to 7.5 days. Probability of developing clinical disease after infection varied from 82% (IQ range 90–70%) with high-virulent to 63% (IQ range 89–60%) with low-virulent strains. Reduction in feed consumption was estimated to last 5 (SD ± 2) days in cattle infected by a low-virulent FMDv strain and 7 (SD ± 2) days for high virulent strains. The study results can be used in combination with experimental and outbreak investigation data to parameterize FMDv-transmission models to evaluate intervention responses during hypothetical FMD epidemics in beef feedlot populations in the U.S. [ABSTRACT FROM AUTHOR]

Enrofloxacin is registered for therapeutic use in beef cattle to treat bovine respiratory disease in Canada. A murine model was used to experimentally examine the impact of therapeutic administration of enrofloxacin on fluoroquinolone resistance development in Campylobacter jejuni. Administration of enrofloxacin to mice via subcutaneous injection or per os routes resulted in equivalent levels of bioactive enrofloxacin within the intestine, but bioactivity was short-lived (<48 h after cessation). Enrofloxacin administration did not affect densities of total bacteria, Firmicutes, or Bacteroidetes in digesta and had modest impacts on densities of Enterobacteriaceae. All mice inoculated with C. jejuni NCTC 11168 became persistently colonized by the bacterium. Enrofloxacin reduced C. jejuni cell densities within the cecal and colonic digesta for all treatments, and densities shed in feces as a function of antibiotic duration. None of the C. jejuni isolates recovered from mice after administration of enrofloxacin (n = 260) developed resistance to ciprofloxacin regardless of method or duration of administration. Furthermore, only modest shifts in the minimum inhibitory concentration of the isolates by treatment were noted. The study findings indicate that the risk posed by short-term subcutaneous administration of enrofloxacin for the development of fluoroquinolone resistance in mammals is low. [ABSTRACT FROM AUTHOR]

To evaluate the effects of a Saccharomyces cerevisiae fermentation product (SCFP; Original XPC, Diamond V, Cedar Rapids, IA) on growth performance and antioxidant defense of newly weaned beef cattle, 180 single- source steers (278 ± 21 kg; SD) were used in a 56-d receiving study. Seven days after arrival, steers were blocked by body weight (BW) to pens of 6 and randomly assigned to treatments: SCFP at 0 (CON), 14 (SCFP14), or 28 (SCFP28) g·steer-1·d-1. Pen was the experimental unit (n = 10 per treatment). On day 0, steers were boostered against Bovine Viral Diarrhea Virus (BVDV) Type 1 and 2 (Vista Once, Merck, Madison, NJ). Weights were collected on days 1, 0, 14, 27, 42, 55, and 56. One steer per pen was bled on days 0, 14, 27, 42, and 56 for analysis of BVDV antibody titers; blood from days 0, 27, and 56 was analyzed for red blood cell lysate superoxide dismutase (SOD) activity and glutathione (total = tGSH, oxidized = GSSG, and reduced = GSH) concentrations, plasma malondialdehyde (MDA) concentrations, and serum lysozyme activity. Performance and blood data were analyzed as a randomized complete block design using Proc Mixed of SAS with fixed effects of treatment and block and random effect of pen. Linear and quadratic contrast statements were used. Antibody titers were log transformed and analyzed as repeated measures. There were no treatment by day interactions (P = 0.16), and no linear or quadratic effects of SCFP on feedlot performance, antibody titers, or lysozyme activity (P > 0.10). Day 27 MDA concentrations tended to linearly increase (P = 0.09). A quadratic effect of SCFP on day 56 SOD activity (P = 0.004) was driven by lesser activity for SCFP14-fed steers. On day 27, a tendency for a quadratic effect of SCFP (P = 0.09) on GSH was driven by greater concentrations for SCFP14-fed steers resulting in a lesser GSSG:GSH ratio (P = 0.05). Greater GSH for SCFP14-fed steers caused a tendency for a quadratic effect on day 56 (P = 0.07); however, this did not result in an effect of SCFP on the GSSG:GSH ratio (P = 0.25). A tendency for a linear effect of SCFP on tGSH was noted on day 56 (P = 0.09). Morbidity data were analyzed using Proc Glimmix of SAS. There was a quadratic effect of SCFP on percentage of respiratory treatments prior to day 14 (P = 0.04). These results could indicate lesser levels of oxidative stress for steers receiving SCFP at 14 vs. 0 or 28 g/d. Under the conditions of this study, no performance benefit of SCFP was noted. [ABSTRACT FROM AUTHOR]

Liver abscesses (LA) in cattle negatively affect feedlot performance by decreasing ADG, feed intake, and G:F ratio. Abscessed livers are condemned and abdominal adhesions associated with LA can result in extensive carcass trimming during harvest, further compounding adverse economic impact. Given regulatory changes pertaining to the use of in-feed antibiotics in cattle production, there is growing interest in alternatives to antibiotics for LA control. The objective of this study was to evaluate the use of antioxidants, crystalline ascorbate (AOX), and alpha-tocopherol acetate, for mitigation of LA in feedlot cattle. Yearling crossbred heifers (n = 392; initial BW 481 ± 9.4 kg) were blocked by previous treatment and allocated randomly to 24 dirt-surfaced feedlot pens (10 m × 35 m) with 14 heifers/pen. Heifers were weighed, implanted with Component TE-200 implants, and placed into feeding pens. Finishing diets consisted of 60% steam-flaked corn, 30% wet corn gluten feed, 8% alfalfa, and 2% supplement (DM basis) that provided 300 mg/d monensin, and either 200 IU/d alpha-tocopherol acetate (CTL) or 2,000 IU/d alpha-tocopherol acetate plus 500 mg/d crystalline AOX. Heifers were fed once daily ad libitum for 94 d, then weighed and transported 450 km to a commercial abattoir for harvest. Hot carcass weight and incidence/severity of LA were determined the day of harvest, and carcass traits were evaluated following 36 h of refrigeration. Compared to CTL, feeding AOX tended to decrease DMI (10.66 vs. 10.31 kg/d; P = 0.08) and improve G:F (0.1204 vs. 0.1254; P = 0.12), but did not impact ADG, incidence of LA (25.6 vs. 23.5% for CTL and AOX, respectively), HCW (828.4 vs. 830.5 kg for CTL and AOX, respectively), or other carcass traits (P > 0.20). In conclusion, feeding antioxidants are not a viable alternative to decrease incidence of LA in finishing cattle. [ABSTRACT FROM AUTHOR]

Mycoplasma bovis can be a bacterial inhabitant of the upper respiratory tract of healthy bovines. In body regions other that the upper respiratory tract however, M. bovis is associated with a number of clinical syndromes such as bovine respiratory disease (BRD). This study used two enzyme-linked immunosorbent assays to assess the sero-status of M. bovis -specific antibodies in Australian feeder cattle at the time of feedlot induction and at approximately 42 days on feed (follow-up). The apparent sero-prevalence of M. bovis -specific antibody at induction was estimated to be 3.5% (95% confidence interval [CI] 2.0–5.0%, 47/1354) and 25.3% (95% CI 21.9–28.8%, 343/1354) at follow-up. Exposure to M. bovis between induction and follow-up as demonstrated by an increase in serum antibodies was estimated to be 19.4% (95% CI 16.2–22.6%, 261/1349). Risk factors associated with sero-positivity at feedlot induction included the region where animals were 28 days prior to induction and saleyard exposure at least 27 days prior to induction. Risk factors associated with a sero-increase between induction and follow-up included breed, source region and access to water shared with an adjoining pen of animals. Of these, shared pen water was considered the most important (odds ratio [OR] 3.3, 95% CI 1.5–7.4, p = 0.003). Animals exposed to M. bovis between induction and follow-up were at a substantially increased risk of BRD (OR 2.2, 95% CI 1.4–3.4, p = 0.001). This is the first Australian study that has identified risk factors for M. bovis sero-positivity and sero-increase and shown an association between sero-increase and the risk of BRD in the feeder cattle population. These findings suggest that M. bovis is a significant pathogen in the Australian feeder cattle population. In addition, identification of defined risk factors associated with an increased risk of exposure to M. bovis can assist in the development of targeted control measures to reduce the economic impact of M. bovis associated disease and BRD in feeder cattle. [ABSTRACT FROM AUTHOR]

Highlights • Co-mingling at an auction market did not influence airways bacterial communities. • Bacterial diversity in the nasopharynx decreased after feedlot placement. • Relative abundance of Mycoplasma significantly increased after feedlot placement. • Composition of nasopharyngeal bacterial communities differed between feedlots. Abstract The objective was to study effects of transportation to and co-mingling at an auction market on nasopharyngeal and tracheal bacterial communities of feedlot cattle. Two groups of 30 Angus-cross heifers were studied from weaning to 28 d after arrival at a feedlot. For each group, half the heifers were either transported directly to a feedlot after weaning (RANC) or transported to and co-mingled at an auction market for 24 h before being placed in a feedlot (AUCT). Deep nasal swabs (DNS) and trans-tracheal aspirates (TTA) were collected at weaning (d0) and at on-arrival processing at the feedlot (d2). At 7 (d9) and 28 d (d30) after arrival, DNS were repeated. The DNA was extracted from DNS and TTA and the V4 region of the 16S rRNA gene sequenced (MiSeq). Alpha diversity analysis did not reveal differences between AUCT and RANC. However, bacterial diversity decreased over time in the nasopharynx, especially at d9. Although beta-diversity was not different between AUCT and RANC, interval after arrival and feedlot where heifers were placed affected composition of the nasopharyngeal bacterial communities. In both groups, a large increase in Mycoplasma was observed after arrival; in one group, Mycoplasma bovis was dominant at d9 and remained dominant until d30. However, in the other group, Mycoplasma dispar dominated at d9 and was replaced by Moraxella at d30. We concluded that transportation to and co-mingling at an auction market for 24 h did not significantly influence diversity or composition of nasopharyngeal or tracheal bacterial communities. [ABSTRACT FROM AUTHOR]

Background: Thoracic ultrasonography (TUS) can be used to assess the extent and severity of lung lesions associated with bronchopneumonia (BP) in feedlot cattle. Hypothesis/Objectives: To assess inter‐rater agreement and reliability of TUS findings in feedlot cattle, with or without naturally occurring BP. Animals: Feedlot steers with (n = 210) or without (n = 107) clinical signs of BP that were assessed by TUS in a previous case‐control study. Methods: A random sample of 50 TUS videos (16‐s duration) were scored by 6 raters with various levels of TUS expertise. Lung consolidation, comet tail artifacts, pleural irregularity and effusion were scored. Inter‐rater agreement was assessed using raw percentage of agreement (Pa), Cohen's and Fleiss' Kappa (κ), and Gwet agreement coefficient (AC1). Intra‐class correlation (ICC) was determined for variables with continuous measurements (mixed factorial design). Results: Median (interquartile range [IQR]) Pa were 0.84 (0.80‐0.89), 0.82 (0.80‐0.87), 0.62 (0.53‐0.67), and 0.82 (0.75‐0.86) for presence of lung consolidation, comet tails, pleural irregularity, and pleural effusion, respectively. For the same lesions, Fleiss κ (95% confidence intervals [CI]) were 0.67 (0.49‐0.86), 0.56 (0.33‐0.80), 0.20 (−0.05 to 0.44), and 0.36 (0.10‐0.61), respectively. AC1 were 0.68 (0.51‐0.86), 0.73 (0.58‐0.89), 0.21 (−0.01 to 0.44), and 0.71 (0.51‐0.92), respectively. Moderate reliability was found among raters for all quantitative variables (ICC ranged from 0.52 to 0.70). Conclusions and Clinical Importance: Inter‐rater agreement was good for presence of lung consolidation, comet tails and pleural effusion (based on Pa and AC1) but was slight to poor for pleural irregularity. [ABSTRACT FROM AUTHOR]

The venereal diseases bovine trichomoniasis (BT) and bovine genital campylobacteriosis (BGC) cause economic losses in endemic areas like La Pampa province in Argentina where beef cattle are usually extensively managed. This study used data compiled between 2007 and 2014 by a Provincial Program for the Control and Eradication of venereal diseases in order to develop and analyze retrospective models of time series for BT and BGC. Seasonality and long-term trend were explored with decomposition and simple regression methods. Autoregressive Integrated Moving Average models (ARIMA) were used to fit univariate models for the prevalence and persistence of BT and BGC. Autoregressive Integrated Moving Average with Explanatory Variable models (ARIMAX) were used to analyze the association between different time series, replacement entries and herd samplings. The prevalence and persistence of BT and BGC have decreased from 2007 to 2014. All the BT and BGC time series are seasonal and their long-term trend is decreasing. Seasonality of BT and BGC is similar, with higher rates of detection in autumn-winter than is spring-summer. Prevalence and persistence time series are correlated, indicating their changes are synchronic and follow a similar time pattern. Prevalence of BT and BGC showed the best fitting with the ARIMA (0,0,1)(0,1,1)12 model. While for persistence of BT and BGC, the best adjustment was with the same model with no seasonal difference where the current number of cases depends on the moving averages of the month and the previous season. Including covariates improve the fitting of univariate models, in addition, estimations using ARIMAX models are more precise than using ARIMA models. The time distribution of the samplings could be increasing the false negative ratio. According to the obtained results, the ARIMA and ARIMAX models can be considered an option to predict the BT and BGC prevalence and persistence in La Pampa (Argentina). [ABSTRACT FROM AUTHOR]

Our objective was to describe the probability of detecting seven serogroups of enterohaemorrhagic Escherichia coli (EHEC-7) of public health importance in faecal samples from beef cow-calf herds and to test for factors associated with their detection. Fresh faecal samples (n = 85) from two Mississippi and two Nebraska herds were collected in each of four seasons. Samples were tested for each EHEC-7 serogroup by a molecular screening assay. Separate management groups within herds were sampled, and group-level factors were recorded. To measure the effects of factors on faecal shedding of EHEC-7, separate multivariable logistic regression models were used, accounting for the random effect of clustering by group within farm. Statistical significance was set α = 0.05. Fifty-nine samples (4.3%) were positive for EHEC O26, and Nebraska samples were more likely to be positive than Mississippi samples (OR = 12.4, 95% CI: 1.1, 139.2). Forty-four samples (3.2%) were positive for EHEC O45. Odds for detection were greater in the summer than all other seasons combined (OR = 4.2, 95% CI: 1.3, 14.0), and odds decreased if a precipitation event occurred (OR = 0.07, 95% CI: 0.006, 0.8). EHEC O103 was detected in 66 samples (4.9%) with increased probability to be detected at increased temperature. EHEC O111 was detected in 71 samples (5.2%), and 43 samples (3.2%) were positive for EHEC O145. Both EHEC O111 and O145 were associated separately with season, with greater probability for detection in the summer. Eighteen (1.3%) and 68 (5.0%) samples were positive for EHEC O121 and EHEC O157, respectively. We failed to detect significant explanatory factors associated with probability to detect EHEC O121 or O157. Factors that vary by time and place, such as precipitation, ambient temperature, region and season, are uniquely associated with the probability to detect EHEC-7 in fresh faeces collected from cow-calf herds. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) in bacterial respiratory pathogens in high-risk stocker cattle has been poorly characterized. The objective of this study was to describe the prevalence of multidrug resistant (MDR; resistance to > 3 antimicrobial classes) respiratory pathogens in 50 conventionally managed stocker cattle over 21 days after arrival. Cattle received tildipirosin metaphylaxis on day 0 and were eligible to receive up to 3 additional antimicrobials for bovine respiratory disease (BRD): florfenicol, ceftiofur and enrofloxacin. Nasopharyngeal swabs were collected on days 0, 7, 14, and 21 for bacterial culture and antimicrobial susceptibility testing using disc diffusion and broth microdilution. Mannheimia haemolytica was isolated from 5 of 48, 27 of 50, 44 of 50, and 40 of 50 cattle on days 0, 7, 14, and 21, respectively. One of 5, 27 of 27, 43 of 44, and 40 of 40 M. haemolytica were MDR on days 0, 7, 14, and 21, respectively. Pasteurella multocida was isolated from 6 of 48 cattle on day 0 and none were MDR; no other pathogens were isolated. Twenty-four cattle required at least one BRD treatment; M. haemolytica was isolated before treatment from 13 of 24 cattle; all were MDR. One hundred-eighteen M. haemolytica isolates were subjected to pulsed-field gel electrophoresis (PFGE); multiple genotypes were identified. Whole genome sequencing of 33 isolates revealed 14 known AMR genes. Multidrug resistant M. haemolytica can be highly prevalent and genetically diverse in stocker cattle; additional research is necessary to determine factors that influence prevalence and the impact on cattle health. [ABSTRACT FROM AUTHOR]

Specific nasopharyngeal bacterial communities can provide colonization resistance against respiratory pathogens in cattle. However, the role of bacterial communities of the lower airways in respiratory health remains largely unknown. Therefore, our objective was to compare nasopharyngeal and tracheal bacterial communities between healthy feedlot cattle and those with bronchopneumonia (BP). Deep nasal swabs and trans-tracheal aspiration samples were collected from steers with (n = 60) and without (n = 60) BP at 4 feedlots in Western Canada. After DNA extraction, 16S rRNA gene (V4) was amplified and sequenced. Alpha-diversity analysis revealed a lower bacterial diversity in the nasopharynx and trachea of steers with BP compared to healthy pen-mates. Bacterial communities present within the airways clustered into 4 distinct metacommunities that were associated with sampling locations and health status. Metacommunity 1, enriched with Mycoplasma bovis , Mannheimia haemolytica and Pasteurella multocida , was dominant in the nasopharynx and trachea of steers with BP. In contrast, metacommunity 3, enriched with Mycoplasma dispar, Lactococcus lactis and Lactobacillus casei , was mostly present in the trachea of healthy steers. Metacommunity 4, enriched with Corynebacterium, Jeotgalicoccus, Psychrobacter and Planomicrobium, was present in the nasopharynx only. Metacommunity 2, enriched with Histophilus somni , Moraxella and L. lactis, was present in both healthy and sick steers, but was primarily detected in one feedlot. We concluded that distinct bacterial metacommunities inhabited the nasopharynx and trachea of healthy feedlot cattle and those with BP. Because L. lactis and L. casei can inhibit M. haemolytica growth in vitro , their presence in healthy steers may have provided colonization resistance against bacterial respiratory pathogens. [ABSTRACT FROM AUTHOR]

The bovine gastrointestinal microbiota is a complex polymicrobial ecosystem that plays an important role in maintaining mucosal health. The role of mucosal microbial populations in the pathogenesis of gastrointestinal diseases has been well established in other species. However, limited information is available about changes in the fecal microbiota that occur under disease conditions, such as hemorrhagic diarrhea in feedlot cattle. The objectives of this study were to characterize the differences in fecal microbiota composition, diversity and functional gene profile between feedlot calves with, and without, hemorrhagic diarrhea. Deep fecal swabs were collected from calves with hemorrhagic diarrhea (n = 5) and from pen matched healthy calves (n = 5). Genomic DNA was extracted, and V1-V3 hypervariable region of 16S rRNA gene was amplified and sequenced using the Illumina MiSeq sequencing. When compared to healthy calves, feedlot cattle with hemorrhagic diarrhea showed significant increases in the relative abundance of Clostridium , Blautia and Escherichia, and significant decreases in the relative abundance of Flavobacterium, Oscillospira, Desulfonauticus, Ruminococcus, Thermodesulfovibrio and Butyricimonas. Linear discriminant analysis effect size (LEfSe) also revealed significant differences in bacterial taxa between healthy calves and hemorrhagic diarrhea calves. This apparent dysbiosis in fecal microbiota was associated with significant differences in the predictive functional metagenome profiles of these microbial communities. In summary, our results revealed a bacterial dysbiosis in fecal samples of calves with hemorrhagic diarrhea, with the diseased calves exhibiting less diversity and fewer observed species compared to healthy controls. Additional studies are warranted in a larger cohort of animals to help elucidate the trajectory of change in fecal microbial communities, and their predictive functional capacity, in calves with other gastrointestinal diseases. [ABSTRACT FROM AUTHOR]

In Piedmontese cattle breed, the sporadic detection of Lipomatous Myopathy (LM) has been reported. The phenotypic disease expression consists in degeneration and infiltration of the muscular tissue characterized by replacement of myofibers with adipose tissue. The aim of this study was to investigate the existence of genetic loci associated with lipomatous myopathy in Piedmontese cattle breed through a genome wide association study based on a DNA pooling design. The samples used for the study were collected from a meat cutting plant, pairing cases and controls within farms. Samples of different muscles (diaphragm, superficial and deep pectoral, intercostal, sternocleidomastoid group and vastus lateralis ) were histopathologically and enzymatically classified as cases and controls. DNA pools of cases and controls were constructed. Equal amounts of DNA were pooled from individuals for the constitution of 4 pools (2 independent biological replicates for cases and 2 for controls). Technical duplicates were also built and all pools genotyped with the Illumina BovineHD BeadChip three time each, for a total of 24 chip array positions. SNPs positions were based on the UMB 3.1 bovine assembly. The B-allele frequencies (BAF) for each array replicate were used in a specific pipeline in R software to perform multiple marker tests after excluding the 5% of SNPs showing the highest BAF variability from the replicate arrays within tail, as well as the monomorphic SNPs. A total of 41 QTLRs were identified on the 29 bovine autosomes, and 4 on the X chromosome. A subset of the identified markers fall inside or nearby genes involved in myogenesis, adipogenesis and cell to cell adhesions. The biological role of these genes in the onset of lipomatous myopathy has been identified looking at the known functions of the encoded proteins on the GeneCards database. Gene networks have been identified using STRING. [ABSTRACT FROM AUTHOR]

The use of silvopastoral systems (SPS) can be a good alternative to reduce the environmental impacts of livestock breeding in Brazil. One of the reasons for its scarce adoption is the lack of information on health and productivity of cattle raised under these conditions. The experiment reported here was designed to compare the infestation by external parasites – the cattle tick ( Rhipicephalus microplus ), horn fly ( Haematobia irritans ), and larvae of the botfly ( Dermatobia hominis ) – in beef cattle raised in a SPS and a conventional pasture system (CPS), evaluated for 24 months. Data on air and soil temperature, solar radiation, wind incidence and water balance were used to characterize the SPS and CPS. R. microplus adult females and D. hominis larvae were counted on the body of each animal to determine the parasites burdens, but we did not find significant differences between the two systems. Horn flies counts on animals’ body, and analysis of the horn fly and its pupal parasitoids associated with the dung pats were obtained in the two systems. Horn fly infestation was significantly lower ( p = 0.01 ) in the SPS (13.17 ± 3.46) in comparison with the CPS (24.02 ± 4.43). In SPS and CPS, respectively, the mean densities of pupae of H. irritans in dung pats were 9.8 and 10.7; the mean density of adults of H. irritans , 3.7 and 3.5; and the density of its pupal parasitoids were 20.5 and 5.4. The effect of production system was significant ( p < 0.05 ) only for the occurrence of pupal parasitoids of the horn fly, where the greatest occurrences of these natural enemies were in the SPS. These data indicate that natural enemies were able to control, at least partially, the horn fly populations in the cattle. [ABSTRACT FROM AUTHOR]

The objectives of this experiment were to determine the association of circulating cortisol, lactate, and glucose at, and prior to, weaning with ADG and incidences of bovine respiratory disease (BRD) in beef cattle. A blood sample was collected approximately 3 wk prior to weaning and at weaning from genetically diverse steers and heifers (n = 451). Cattle were weighed periodically throughout the study and ADG was calculated for the preweaning period (152 ± 15 d), the receiving period (45 d postweaning), the finishing period (200 d), and total postweaning ADG. Incidences of BRD were recorded and analyzed as a binary trait. Lung lesions were recorded at slaughter. Preweaning serum cortisol concentrations were positively associated (P = 0.040) with receiving ADG and explained 0.74% of the variance of receiving ADG. Preweaning glucose concentrations were positively associated (P < 0.001) with preweaning ADG and negatively associated with receiving (P = 0.003), finishing (P = 0.008), and total postweaning ADG (P = 0.002) and explained 2.0% of the variance in total postweaning ADG. Variation in preweaning serum glucose concentrations could be indicative of variation in milk consumption, and therefore indicate calves receiving less milk grow slower prior to weaning, but experience compensatory gain postweaning. Cattle that were diagnosed with BRD (n = 130) grew slower during the receiving phase (P = 0.004), but total postweaning ADG was not different from cattle not diagnosed with BRD (P = 0.683). Additionally, cattle that were diagnosed with BRD in the feedlot tended (P = 0.062) to have slightly lower preweaning serum glucose concentrations. Using a logistic regression analysis, none of the serum variables measured at or before weaning were predictive of developing BRD (P > 0.180). Weaning serum glucose concentrations tended to be predictive of the presence of lung lesions at weaning (P = 0.060). These data indicate that glucose measured early in life is associated with growth rate, and could indicate that carbohydrate metabolism could contribute to variation in ADG. [ABSTRACT FROM AUTHOR]

The objective of this study was to illustrate the implementation of a mixed-model-based structural equation modeling (SEM) approach to observational data in the context of feedlot production systems. Different from traditional multiple-trait models, SEMs allow assessment of potential causal interrelationships between outcomes and can effectively discriminate between direct and indirect effects. For illustration, we focused on feedlot performance and its relationship to health outcomes related to Bovine Respiratory Disease (BRD), which accounts for approximately 75% of morbidity and 50–80% of deaths in feedlots. Our data consisted of 1430 lots representing 178,983 cattle from 9 feedlot operations located across the US Great Plains. We explored functional links between arrival weight (AW; i  = 1), BRD-related treatment costs (Trt$; as a proxy for health; i  = 2) and average daily weight gain (ADG; as an indicator of productive performance i  = 3), accounting for the fixed effect of sex and correlation patterns due to the clustering of lots within feedlots. We proposed competing plausible causal models based on expert knowledge. The best fitting model selected for inference supported direct effects of AW on ADG as well as indirect effects of AW on ADG mediated by Trt$. Direct effects from outcome i’ to outcome i are quantified by the structural coefficient λ ii ' , such that every unit increase in kg/head of AW had a direct effect of increasing ADG by approximately (estimate ± standard error) λ ˆ 31 = 0.002 ± 0.0001  kg/head/day and also a direct effect of reducing Trt$ by an estimated λ ˆ 21 = $ 0.08 ± 0.006 USD per head. In addition, every $1 USD spent on Trt$ directly decreased ADG by an estimated λ ˆ 32 = 0.004 ± 0.0006 kg/head/day. From these estimates, we show how to compute the indirect, Trt$-mediated, effect of AW on ADG, as well as the overall effect of AW on ADG, including both direct and indirect effects. We further compared estimates of SEM-based effects with those obtained from standard linear regression mixed models and demonstrated the additional advantage of explicitly distinguishing direct and indirect components of an overall regression effect using SEMs. Understanding the direct and indirect mechanisms of interplay between health and performance outcomes may provide valuable insight into production systems. [ABSTRACT FROM AUTHOR]

A distinct difference between veterinary and human medicine is the routine use of antimicrobial mass medications (prophylaxis, metaphylaxis) to healthy individuals. The need for antimicrobial mass medications is based on beliefs that group/s of animals will contract a bacterial disease (i.e. morbidity) and/or die (i.e. mortality). Bovine respiratory disease (BRD) represents the major indication for cattle antimicrobials worldwide. The objectives were to perform a systematic review and meta-analysis of randomised controlled clinical trials (RCTs) for naturally occurring BRD investigating antimicrobial prophylaxis/metaphylaxis to prevent morbidity/mortality. In total, 58 publications met the inclusion criteria summarizing 169 individual RCTs, spanning 50 years (1966-2016). Antimicrobial prophylaxis and metaphylaxis demonstrated moderate, yet highly variable relative risk reductions in BRD morbidity. These were dependent on the antimicrobial classes used, dependent on metaphylaxis definition, BRD attack rates and duration of the RCTs. Best relative risk reductions were from broad-spectrum critically important antimicrobials, or combinations. BRD prophylaxis/metaphylaxis represents major antimicrobial consumption for highly variable short-term gains in absolute risk reduction of morbidity/mortality. Despite widespread use of prevention products, the need for antimicrobial mass medications should be re-evaluated since the underlying problem is more likely the segmented infrastructure of the feedlot and veal calf industries compared to the disease itself. [ABSTRACT FROM AUTHOR]

Emphysematous lymphangitis was found in the colon of a 2-year-old Holstein-Friesian steer which was conventionally slaughtered for food. At postmortem examination, the wall of a circumscribed region of the colon was involved with emphysematous lesion characterized by the presence of many small gas bubbles. Histologically, this emphysematous lesion proved to be multicystic lymphangiectasis, mainly involving the submucosal tissue. Lymphangiectasis was associated occasionally with granulomatous infiltrates comprised of giant cells and macrophages. A small number of macrophages and eosinophils infiltrated into areas surrounding dilated lymphatic vessels. Histochemical stains failed to demonstrate microorganisms or other pathogens in giant cells and macrophages or elsewhere in the lesioned submucosa. Bacteriological examination failed to reveal any likely pathogen. The present investigation was unable to definitely determine the entry pathway and composition of gaseous matter stagnated within dilated lymphatics. Although an immune-mediated pathogenesis was suggested in the development of the lesions on the basis of the presence of eosinophilic and granulomatous infiltrates, the exact etiology and pathogenesis of this condition which specifically involved lymphatic vessels in the colon remains unknown. [ABSTRACT FROM AUTHOR]

This experiment compared DMI, ruminal forage degradability, and liquid parameters as well as physiological responses in beef cattle receiving a lipopolysaccharide (LPS) challenge or not. Eight ruminally cannulated Angus x Hereford steers (485 ± 16 kg BW) were housed in individual pens on d -7, ranked by BW, and allocated to 1 of 2 treatments administered on d 0: 1) an intravenous (i.v.) bolus dose (0.5 µg/kg of BW, diluted in 5 mL of 0.9% sterile saline) of bacterial LPS (Escherichia coli 0111:B4) or 2) a 5-mL i.v. injection of 0.9% sterile saline (CON). Steers had free-choice access to mixed alfalfa-grass hay, water, and a commercial vitamin + mineral mix during the experiment (d -7 to 6). Hay DMI was evaluated daily from d -5 to 6. Immediately prior to treatment administration (h 0), polyester bags containing 4 g of ground dietary hay (DM basis) were immersed into the rumen of each steer and incubated for 0, 4, 8, 12, 24, 36, and 48 h for DM and NDF degradability evaluation. Steers were also intraruminally pulse-dosed with 5 g of Co-EDTA immediately prior to treatment administration, and rumen fluid samples were collected at 0, 2, 4, 6, 8, 12, 16, and 24 h for ruminal liquid volume and dilution rate calculations. Blood was collected every 2 h from -2 to 8 h, every 4 h from 8 to 16 h, every 12 h from 24 to 72 h, and every 24 h from 96 to 144 h relative to treatment administration. Values obtained before treatment administration were used as a covariate within each respective analysis. Steers receiving LPS had less (P ≤ 0.03) DMI on d 0 and 1 compared with CON steers. Steers receiving LPS had reduced (P ≤ 0.05) rumen liquid volume and dilution rate as well as ruminal disappearance rate and effective degradability of DM and NDF compared with CON steers. Steers receiving LPS had greater (P ≤ 0.05) plasma tumor necrosis factor α at 2 h, greater plasma haptoglobin from 24 to 72 h, greater plasma cortisol from 12 to 16 h, greater serum NEFA from 6 to 48 h, greater plasma insulin and glucose at 2 h, reduced plasma glucose from 4 to 12 h, greater plasma cholecystokinin at 16 h, and greater plasma leptin concentrations at 8, 12, 16, 36, 48, and 60 h after treatment administration compared with CON steers. Hence, LPS administration transiently reduced DMI in steers via physiological reactions that modulate gastrointestinal motility and satiety centers in the central nervous system, in addition to potential host-microbiome endocrine interactions that impaired ruminal hay DM and NDF degradability. [ABSTRACT FROM AUTHOR]

Mycoplasma bovis ( M. bovis ) is a small bacterium that lacks a cell wall. M. bovis infection results in chronic pneumonia and polyarthritis syndrome (CPPS), otitis media, conjunctivitis, and meningitis in feedlot cattle and mastitis in dairy cattle. Numerous studies of peripheral mononuclear cells (PBMC) indicate that M. bovis evades host immunity through targeted effects on immune cell activity, including inhibition of effector function and simultaneous aberrant activation of immune cell activity that has no effect on protection against the bacterium. Few studies have addressed the interaction between M. bovis and neutrophils, one of the most important cell subsets of innate immunity. We hypothesized that M. bovis modifies specific neutrophil activities to support its persistence and systemic dissemination. In this study, we demonstrate that M. bovis enhances neutrophil apoptosis, stimulates production of pro-inflammatory cytokines, IL-12 and TNF-α, inhibits production of nitric oxide (NO) but augments elastase release. We also show that IL-17 an inflammatory cytokine produced by Th-17 cells does not enhance the capacity of neutrophils to destroy M. bovis . These findings present novel mechanisms of mycoplasma evasion of host innate immunity and provide potential opportunities for immuno-therapeutic interventions. [ABSTRACT FROM AUTHOR]

In cows, detrimental effects on fertility are mainly caused by clinical and subclinical endometritis (SEM). As demonstrated in previous work, Piedmontese cattle are affected by a higher rate of infertility and presence of SEM. The objective of this study is to assess the pattern of SEM at 30 and 60 days postpartum by evaluating the correlation between uterine cytology and microbiology, analyzing SEM consequences on reproductive career and verifying the reliability of rising inflammatory proteins - haptoglobin and the test strip test. Seventy healthy cows were enrolled and sampled at 30 and 60 days postpartum; cytology and bacteriology as well as haptoglobin and test strip were evaluated. The ROC curve for cytology set the optimal cut-off at 6.5% at 30 days and 2.5% at 60 days for a Partum-to-Conception (PC) interval of 120 days. The cytological positivity was negatively correlated with fertility, at 30 days, but not at 60 days. A positive bacteriological test was not correlated with an increase in the PC at either 30 or 60 days postpartum. The presence of a calving parlor affect the fertility (P < 0.05) but not the presence of parity or suckling calf and parity. The ROC curve for strip test protein at 30 days postpartum set a cut-off of 2% for PC. No difference in serum haptoglobin was observed between negative or positive cytology/bacteriology in postpartum cattle. The test strip results for proteins have demonstrated a utility at 30 days postpartum for screening the cows that are at risk of developing an increased PC > 120 days. [ABSTRACT FROM AUTHOR]

Background: There is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia.Methods: Various samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods.Results: At the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested.Conclusions: E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7. [ABSTRACT FROM AUTHOR]

Timing of conception, which has been indicated to be negatively influenced by metabolic dysfunctions, can influence lifetime productivity within the cow herd. Therefore, our objective was to analyze the association of milk production, serum metabolites as an indicator of nutrient status, cow BW and BW change, and calf BW with timing of pregnancy in 183 spring-calving beef cows. Cows were retrospectively classified by timing of pregnancy as cows that were diagnosed pregnant by timed AI (TAI; n = 118) or natural breeding (NAT; n = 65). In addition, cows were grouped by age to represent young (3 to 4 yr old), mature (5 to 6 yr old), and old (7 to 9 yr old) cows. Starting approximately d 30 postpartum, cow BW and BCS were recorded and blood samples were collected weekly through the end of breeding. Weekly serum samples were composited by cow within 2 production periods: 1) prebreeding and 2) TAI to end of NAT. Cow BW and BCS did not influence (P = 0.40) timing of pregnancy during the entire study. Similarly, calf BW at birth and weaning were not different (P = 0.30) between timing of pregnancy groups. However, calf BW at weaning and calf value the subsequent year of the study were greater (P < 0.01) for TAI cows than for NAT cows. An age group × treatment interaction (P < 0.01) occurred for serum ß-hydroxybutyrate (BHB). Serum BHB concentrations for mature and old cows were similar regardless of timing of pregnancy. However, serum BHB concentrations for young NAT cows were greater than for young TAI cows. In addition, serum NEFA exhibited (P = 0.04) a timing of pregnancy × sampling period interaction. Prebreeding serum NEFA concentrations were greater for NAT cows than for TAI cows. In contrast, serum NEFA concentrations during the NAT season were similar regardless of timing of pregnancy. Area under the curve of the receiver-operating characteristic curve for young cows' circulating BHB concentrations (0.66) was an acceptable predictor for pregnancy by TAI (P < 0.01). Results from this study indicate that only the young, postpartum beef cows during early lactation were susceptible to the measured metabolic dysfunctions of elevated blood BHB concentrations, which may have caused a delay in the timing of pregnancy. [ABSTRACT FROM AUTHOR]

The objective of this project was to identify risk factors associated with the probability of failing to resolve clinical signs of bovine respiratory disease (BRD) after initial antimicrobial treatment. A retrospective data analysis was performed with 194,062 animals treated for BRD with an antimicrobial from 10 U.S. feedlots from 2005 to 2009. A binary variable classified cattle as a treatment failure if they were retreated for BRD or died following an initial BRD treatment. A generalized logistic mixed model was created to evaluate associations of quarter of the year at feedlot arrival, arrival weight, sex, risk classification (high vs. low), days on feed at first BRD treatment, and rectal temperature at first BRD treatment and all 2-way interactions with the probability of first treatment failure for BRD. A total of 64,683 out of 194,062 (33.3%) of cattle initially treated for BRD were classified as treatment failures due to death or retreatment. Multiple 2-way interactions were present. High-risk calves had greater probability of first treatment failure compared with low-risk calves, but this effect was modified by quarter of arrival, days on feed at first treatment, and rectal temperature category. The effect of arrival weight category was modified by days on feed at first treatment of BRD and quarter of arrival for probability of first treatment failure. Multiple arrival and treatment characteristics were associated with the probability of first BRD treatment failure. Knowledge of these factors can lead future prospective studies to improve the prediction of treatment failure and provide baseline results for the industry. [ABSTRACT FROM AUTHOR]

The objective of this research was to examine the effects of dexamethasone (DEX) treatment on various aspects of immunity following administration of a multivalent respiratory vaccine, using a model intended to mimic acute versus chronic stress. Angus × Hereford steers (n = 32; 209 ± 8 kg) were stratified by BW and randomly assigned to 1 of 3 treatments: 1) acute stress (ACU), in which 0.5 mg/kg BW DEX was intravenously administered at 1000 h only on d 0; 2) chronic stress (CHR), in which 0.5 mg/kg BW DEX was intravenously administered at 1000 h on d -3 to 0; or 3) control (CON), in which no DEX was administered. Steers were fitted with indwelling jugular catheters and rectal temperature (RT) recording devices on d -4 relative to vaccination and placed in individual stanchions in an environmentally controlled facility. Blood samples were collected and serum was isolated 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 multivalent respiratory vaccination at 1200 h on d 0. Additional blood samples were used to analyze complete blood cell count (CBC) and functional capacities of neutrophils. There was a treatment × time interaction (P < 0.01) for RT such that DEX treatment in CHR and ACU steers decreased RT on d -3 and 0, respectively. A treatment × time interaction (P < 0.01) was observed for total white blood cells (WBC), neutrophils, lymphocytes, and monocytes. Specifically, DEX increased WBC and neutrophils in CHR and ACU steers (P < 0.001) yet decreased lymphocytes in CHR steers (P = 0.02) compared with CON steers. Neutrophil concentration increased rapidly, within 2 h of the DEX infusion, in ACU steers. Monocytes transiently increased (P < 0.001) in response to DEX treatment in CHR and ACU steers. In contrast, eosinophils were greater (P < 0.01) in CON steers than in ACU and CHR steers. A treatment × time interaction (P = 0.004) was observed for interferon-γ, with CON cattle exhibiting greater concentrations than the ACU and CHR cattle at 5 h after vaccination, through d 3. Treatment also influenced (P ≤ 0.001) the expression of L-selectin on the surface of neutrophils. The percentage of neutrophils engaging in phagocytosis and the oxidative burst were suppressed (P ≤ 0.001) among only the CHR steers, whereas the intensity of the oxidative burst was suppressed (P ≤ 0.001) for both ACU and CHR steers. These data suggest that our model induced acute and chronic immunosuppression and defined the acute response to a multivalent vaccine in CON steers. [ABSTRACT FROM AUTHOR]

Assessment of blood L-lactate concentration (LAC) as point-of-care (POC) biomarkers is turning into a typical procedure for different diagnostic purposes in the food animal industry. The purpose of our study was to figure out whether blood LAC measured by a hand held lactate analyzer with different variables could be utilized to anticipate the event of bovine respiratory disease (BRD) in feedlot cattle. Moreover, assess the blood LAC stability over different time point in clinically healthy feedlot cattle. Blood sample was collected at entry during processing (n=104) and at initial diagnosis of BRD (n=24). In addition, clinically healthy pen matched controls calves (n=24) were sampled at the same time of pulling diseased calves for determination of blood LAC using a handheld portable lactate analyzer. In a separate study, selected clinically healthy calves (n=9) were sampled and blood LAC stability at the different time point (0, 30, 60, 90 and 120 minute) was assessed. Logistic regression model revealed blood LAC during initial processing was significantly associated with odds of becoming a BRD case in calves revealing lung score 2. Moreover, blood LAC was significantly different (P=0.02) between clinically healthy and those calves that developed BRD and was significantly correlated (P>0.01) within the different time points. Our results demonstrated that analyzing blood LAC at initial diagnosis of BRD together with other clinical variable might help in the treatment decision. Therefore, further investigation should be designed to correlate blood LAC measurements for prediction of BRD clinical outcomes. [ABSTRACT FROM AUTHOR]

The dynamics of bovine besnoitiosis were studied in an area where the disease is endemic. A four-year longitudinal study was conducted for the first time in three infected beef cattle herds located in the Urbasa-Andía Mountains (Navarra, Spain). Each herd was visited four to seven times, and clinical and serological prevalence rates and incidence rates were estimated. Clinical inspections to identify compatible clinical signs with the disease stages were conducted at the beginning and end of the study. Serological assessment was initially performed by ELISA. Seronegative animals with clinical signs and seropositive animals with relative index per cent ( RIPC) values lower than 30 that did not increase during the study period were analysed by Western blot to optimize the sensitivity and specificity of the ELISA test. Clinical prevalence rates were slightly higher (62% on average) than the seroprevalence rates (50% on average), and tissue cysts located in the vestibulum vaginae and sclera were the most frequently detected clinical signs. The proportion of seropositive animals with clinical signs varied from 16.7% to 73.6% among the herds, and 17% of cattle with clinical signs proved to be seronegative by both serological tests. An average 22% serological incidence rate was also reported in addition to clinical incidence rates that varied from 12.5% to 16.7%. Additionally, parasitemia was investigated in the herd that showed the highest clinical and seroprevalence rates. Only one PCR positive blood sample was detected. Thus, the role that blood may play in parasite transmission needs to be further investigated. Infected herds maintained both high prevalence and incidence rates in the absence of control measures and a high number of parasite carriers. Finally, economic impact studies on reproductive and productive losses associated with besnoitiosis need to be performed to implement a cost-benefit control programme. [ABSTRACT FROM AUTHOR]

Bovine besnoitiosis is a parasitic disease caused by the protozoan Besnoitia besnoiti. Described many decades ago, recent epidemiological studies reveal its important spread within Europe in the last years. To date, many epidemiological aspects related to life cycle, routes of transmission, incidence rates and associated risk factors are lacking; hence, the establishment of appropriate disease control programmes poses an important challenge. Thus, the aim of the present study was to determine the epidemiological pattern of the disease in an endemic herd reared under extensive conditions (Spanish Pyrenees) by identifying main factors associated with infection and clinical disease dynamics. The study population consisted of 276 Brown Swiss and Pirenaica adult animals and 145 calves born and weaned at the farm during the study. Three sampling time frames were used: January 2010, September 2010 and February 2011, which allowed us to differentiate two periods designated as mountain and valley periods. The data related to animals (breed, sex and age) and herd management (animal grouping and time in housing) were recorded. The data collection methodology was mainly based on clinical examinations and defining the serological status against bovine besnoitiosis by the immunofluorescent antibody testing of blood samples. The total prevalence among adult animals was 38.34% (CI95%: 34.53–42.07), with 18.54% of seropositive animals showing clinical signs. In regard to the cumulative incidence, 34.57% of new infections were detected during the mountain period, in contrast to the 24.59% observed in the valley period. The incidence density was 0.058 and 0.061 new infections per animal-month for the mountain and valley periods, respectively. According to the seroepidemiological study, the seroconversion probability of B. besnoiti infection was directly associated with the number of seropositive cows with whom an animal had been stabled as well as the housing period duration, supporting horizontal transmission by close contact as one of the most important methods of disease spread. In addition, the risk of developing the clinical course increased with age, and the presence of clinical signs was related to higher antibody responses. Among calves (from 3.1 to 7.1 months old) sampled once at weaning, the total seroprevalence was 15.17% (CI95%: 9.36–21.04), and the chronic stage was observed in three animals, supporting the ability of B. besnoiti to infect and even cause disease in animals less than 6 months old. Finally, the risk of calf seroconversion was positively related to the serological status of the cows, suggesting postnatal transmission between dams and offspring by contact during the suckling period. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a zoonotic protozoan parasite that thrives in Estonia. In this nationwide cross-sectional study, we tested sera from 3991 cattle, collected from 228 farms in 2012–2013, for anti- T. gondii immunoglobulin G antibodies using a commercial direct agglutination test. Titer of 100 was set as cut-off: samples that tested positive at the dilution 1:100 were defined as positive. The apparent animal-level seroprevalence was 18.62%. At least one seropositive animal was found on 68.86% of the farms, and seropositive cattle were detected in all counties. The seroprevalence appeared to increase with age until five years (60–71 months) of age, but had no obvious pattern in the older animals. Animals of the local Estonian Red breed had higher odds to test seropositive than did animals of the Estonian Holstein breed. Whether the farm focused on dairy or beef cattle was not associated with an animal testing T. gondii seropositive nor with finding at least one T. gondii seropositive animal on the farm. The odds of finding at least one T. gondii seropositive animal on the farm were higher if the herd size was above median (105 in dairy and mixed dairy farms; 35 in beef and mixed beef farms). The results indicate that T. gondii is endemic within the agricultural setting in Estonia and present on the majority of cattle farms. [ABSTRACT FROM AUTHOR]

Toxocara vitulorum is an ascarid that is frequently found in sub-tropical regions but little is known about infections in more temperate climates. In this study, we report the occurrence of this parasite in a beef cattle herd in eastern Germany. In June 2016, large (14-20 cm) cream-colored worms identified as adult T. vitulorum were observed in the feces of 2- to 3-month-old calves. Eggs of this parasite were subsequently detected in pooled fecal samples collected on all three farm sites. The morphological identification was supported by analysis of partial cytochrome c oxidase I and internal transcribed spacer 1 gene sequences. Clinical signs of toxocariasis, such as diarrhea and loss of body weight were not apparent. [ABSTRACT FROM AUTHOR]

Undifferentiated fever, or bovine respiratory disease complex (BRDc), is a challenging multi-factorial health issue caused by viral/bacterial pathogens and stressors linked to the transport and mixing of cattle, negatively impacting the cattle feedlot industry. Common practice during processing at feedlots is administration of antibiotic metaphylaxis to reduce the incidence of BRDc. Nitric oxide (NO) is a naturally occurring nano-molecule with a wide range of physiological attributes. This study evaluated the metaphylactic use of intranasal NO releasing spray (NORS) to control BRDc incidence in calves at low-moderate risk of developing BRDc, arriving at a commercial feedlot as compared to conventional antibiotic metaphylaxis. One thousand and eighty crossbred, multiple-sourced, commingled, commercial, weaned beef calves were screened, enrolled, randomized and treated upon arrival. Animals appearing sick were pulled (from their pen) by blinded pen keepers then assessed for BRDc symptoms; blood samples were taken for haptoglobin quantification and the animals were rescued with an antibiotic. After 35 days both groups showed no significant difference in BRDc incidence (5.2% of animals from NORS group and 3.2% from antibiotic group). Average daily weight gain of animals at day 150 for the NORS cohort was 1.17 kg compared to 1.18 kg for the antibiotic group ( p > 0.05). There was no significant difference in mortality in the first 35 days ( p = 0.7552), however, general mortality over 150 days trended higher in the antibiotic cohort. NORS treatment was shown to be safe, causing neither distress nor adverse effects on the animals. This large randomized controlled study in low-moderate BRDc incidence risk calves demonstrates that NORS treatment, as compared to conventional metaphylactic antibiotics, is non-inferior based on BRDc incidence and other metrics like weight and mortality. These data justify further studies in higher BRDc incidence risk populations to evaluate NORS as an alternative strategy to reduce sub-therapeutic metaphylaxis antibiotic use in beef cattle production. [ABSTRACT FROM AUTHOR]

The objective of this project was to evaluate the effects of antimicrobials approved for parenteral metaphylactic use in feeder and stocker calves on morbidity and mortality for bovine respiratory disease with the use of a mixed treatment comparison meta-analysis. An initial literature review was conducted in April 2016 through Pubmed, Agricola, and CAB (Commonwealth Agricultural Bureau) for randomized controlled trials for metaphylaxis antimicrobial administered parentally to incoming feedlot or stocker calves within 48 h of arrival. The final list of publications included 29 studies, with a total of 37 trials. There were 8 different metaphylactic antimicrobials. Final event outcomes were categorized into bovine respiratory disease (BRD) morbidity cumulative incidence d 1 to ≤ 60 of the feeding period, BRD morbidity cumulative incidence d 1 to closeout of the feeding period, BRD mortality cumulative incidence d 1 to closeout of the feeding period, and BRD retreatment cumulative incidence morbidity d 1 to closeout of the feeding period. Network meta-analysis combined direct and indirect evidence for all the event outcomes to determine mean odds ratio (OR) with 95% credibility intervals (CrIs) for all metaphylactic antimicrobial comparisons. The "upper tier" treatment arms for morbidity d 1 to ≤ 60 included tulathromycin, gamithromycin, and tilmicosin. For BRD mortality cumulative incidence d 1 to closeout and BRD retreatment morbidity d 1 to closeout, classifying the treatment arms into tiers was not possible due to overlapping 95% CrIs. The results of this project accurately identified differences between metaphylactic antimicrobials, and metaphylactic antimicrobial options appear to offer different outcomes on BRD morbidity and mortality odds in feedlot cattle. [ABSTRACT FROM AUTHOR]

The selection of genetically superior individuals is conditional upon accurate breeding value predictions which, in turn, are highly depend on how precisely relationship is represented by pedigree. For that purpose, the numerator relationship matrix is essential as a priori information in mixed model equations. The presence of pedigree errors and/or the lack of relationship information affect the genetic gain because it reduces the correlation between the true and estimated breeding values. Thus, this study aimed to evaluate the effects of correcting the pedigree relationships using single-nucleotide polymorphism (SNP) markers on genetic evaluation accuracies for resistance of beef cattle to ticks. Tick count data from Hereford and Braford cattle breeds were used as phenotype. Genotyping was carried out using a high-density panel (BovineHD - Illumina® bead chip with 777 962 SNPs) for sires and the Illumina BovineSNP50 panel (54 609 SNPs) for their progenies. The relationship between the parents and progenies of genotyped animals was evaluated, and mismatches were based on the Mendelian conflicts counts. Variance components and genetic parameters estimates were obtained using a Bayesian approach via Gibbs sampling, and the breeding values were predicted assuming a repeatability model. A total of 460 corrections in relationship definitions were made (Table 1) corresponding to 1018 (9.5%) tick count records. Among these changes, 97.17% (447) were related to the sire's information, and 2.8% (13) were related to the dam's information. We observed 27.2% (236/868) of Mendelian conflicts for sire-progeny genotyped pairs and 14.3% (13/91) for dam-progeny genotyped pairs. We performed 2174 new definitions of half-siblings according to the correlation coefficient between the coancestry and molecular coancestry matrices. It was observed that higher-quality genetic relationships did not result in significant differences of variance components estimates; however, they resulted in more accurate breeding values predictions. Using SNPs to assess conflicts between parents and progenies increases certainty in relationships and consequently the accuracy of breeding value predictions of candidate animals for selection. Thus, higher genetic gains are expected when compared to the traditional non-corrected relationship matrix. [ABSTRACT FROM AUTHOR]

Bovine respiratory disease (BRD) is the most common and economically detrimental disease of beef cattle during the postweaning period, causing the majority of morbidity and mortality in feedlots. The pathogenesis of this disease often includes an initial viral infection, which can predispose cattle to a secondary bacterial infection. The objective of this experiment was to determine the effects of timing of an intratracheal Mannheimia haemolytica (MH) challenge relative to 72 h of natural exposure to bovine viral diarrhea virus (BVDV) type 1b persistently infected (PI) calves on performance, serum antibody production, total and differential white blood cell (WBC) count, rectal temperature, clinical severity score (CS), and haptoglobin (Hp). Steers (n = 24; 276 ± 31 kg initial BW) were randomly allocated to 1 of 3 treatments (8 steers/treatment) in a randomized complete block design. Treatments were steers not exposed to calves PI with BVDV 1b and not challenged with MH (CON), steers intratracheally challenged with MH 84 h after being exposed to calves PI with BVDV 1b for 72 h (LateCh), and steers intratracheally challenged with MH 12 h after being exposed to calves PI with BVDV 1b for 72 h (EarlyCh). Performance (ADG, DMI, and G:F) was decreased (P < 0.001) for both EarlyCh and LateCh from d 0 to 4. From d 5 to 17, LateCh appeared to compensate for this lost performance and demonstrated increased ADG (P = 0.01) and G:F (P = 0.01) compared with EarlyCh. Both EarlyCh and LateCh had decreased platelet counts (P < 0.001) compared with CON. Antibody concentrations of BVDV and MH were higher (P < 0.05) for both EarlyCh and LateCh compared with CON. Rectal temperature, CS, and Hp increased (P < 0.001) across time from h 4 to 48, h 4 to 36, and h 8 to 168, respectively. Within 24 h of MH challenge, WBC and neutrophil concentrations within the blood increased whereas lymphocyte concentrations decreased. The timing of BVDV exposure relative to a MH challenge appears to influence the CS and acute phase response associated with BRD. As typical beef cattle marketing channels allow for variation in the timing of respiratory pathogen exposure, understanding the physiological changes in morbid cattle will lead to improved management of BRD. [ABSTRACT FROM AUTHOR]

Bovine respiratory disease is the most economically important disease of feedlot cattle in North America. Choice of antibiotic is a critical factor for producers and veterinarians. We previously published a mixed-treatment comparison meta-analysis that combined evidence from published trials and published estimates of comparative efficacy for 12 antibiotics registered for use in the USA. Some of the comparative efficacy estimates were based only on indirect evidence. Since the original review was published, new studies that provide direct evidence of comparative efficacy have been published. We updated the original review to include the current evidence. We also compared the results from the indirect estimates from the prior model with the observed results from randomized control trials. We repeated the original search and found that five of the new studies met the criteria for inclusion in the updated review. Four of these studies provided new data on direct comparisons of active drugs. The results from one study (performed in 2002) that compared ceftiofur pinna and enrofloxacin were inconsistent with the network and were excluded from the analysis. Three new direct comparison studies examined gamithromycin compared with tulathromycin, florfenicol, and tilmicosin. The results of our analysis suggested that the indirect estimates from the prior model provided reasonable estimates of the risk ratios revealed by the primary studies. For example, for the comparison of gamithromycin (referent) with tulathromycin, the original model predicted a risk ratio of re-treatment of 0.54 (95% credible interval 0.27–0.87). The subsequent randomized controlled trial revealed that the observed risk ratio of re-treatment was 0.59 (95% confidence interval 0.45–0.78). The results of other comparisons were also similar. For the gamithromycin (referent) to florfenicol comparison, the observed randomized trial RR was 1.17 (95% confidence interval 0.83–1.64) and the indirect estimate of RR from the prior model was 0.84 (95% credibility interval 0.48–1.3). The gamithromycin to tilmicosin (referent) observed RR from the randomized trial was 0.99 (95% confidence interval 0.67–1.47) and the indirect estimate of RR from the prior model was 1.09 (95% credible interval 0.64–1.79). The results suggested that indirect estimates provided reasonable estimates of RR when direct data were not available. [ABSTRACT FROM AUTHOR]

Feedlot cattle are monitored for the sickness response, both physiological and behavioral, to detect bovine respiratory disease (BRD), but this method can be inaccurate. Diagnostic accuracy may improve if the BRD sickness response is better understood. We hypothesized that steers around peak BRD would have fever, anorexia, and less grooming than controls. We also expected sickness response magnitude to be greater as clinical and pathological severity increased. Unvaccinated steers were assigned to challenge with 1 of 5 BRD viruses or bacteria (BRD challenge; n = 4/pathogen; 20 total), based on susceptibility as determined by serology. Body weight-matched vaccinated animals were given sterile media (Control; n = 4/pathogen; 20 total) and housed by treatment (5 pens/treatment). Rectal temperature was logged every 5 min between 0100 and 0700 h, and time spent feeding (24 h/d), in contact with a brush (13 h/d), and self-licking (24 h/d) were collected from video recordings. Steers were examined and a clinical score (CS) was assigned daily. Bovine respiratory disease challenge steers were euthanized after 5 to 15 d (timing was pathogen specific) and the proportion of grossly affected lung (%LUNG) was recorded. The day of highest CS (peak; d 0) for each BRD challenge steer and the 2 preceding days were analyzed for all variables except self-licking (d 0 only); analogous days were included for Controls. Penwise mixed models (pen was the experimental unit) were used to determine which sickness response elements differed between treatments before and at peak disease, and regression using individual-steer data was used to describe relationships between disease severity (n = 35 for CS and n = 20 for %LUNG) and fever, anorexia, and grooming. Bovine respiratory disease challenge steers had fever (1.1°C higher; P < 0.01) and anorexia (35% lower feeding time; P = 0.03) but did not differ from healthy Controls for brush contact (P = 0.37) or self-licking (P = 0.15). Higher CS and more %LUNG were associated with increased fever (d 0; P ≤ 0.04) and lower feeding (d 0; P < 0.01), brush contact (d 0; P ≤ 0.03), and self-licking (P ≤ 0.05) duration relative to lower CS and less %LUNG. In conclusion, fever and feeding time are good BRD diagnostic measures around peak CS. Further study is needed to clarify why grooming was not a good measure. The sickness response is greater as BRD severity increases; fever is most closely related to CS and anorexia is most closely related to %LUNG. Regardless of which aspect is monitored, cattle with milder disease may be more difficult to detect than sicker animals. [ABSTRACT FROM AUTHOR]

Background Calf output is a key element in determining the profitability of a suckler beef enterprise. Infectious agents such as Bovine Virus Diarrhoea (BVD) virus, colostrum management and parasitic challenge can all affect calf output. Prior to the national BVD eradication programme, there was little published information on either the prevalence or effect of BVD in Irish beef herds. There is little published information on colostrum management practices in Irish commercial beef herds and there have also been few studies published on the prevalence of liver fluke or rumen fluke infection in Irish beef herds. Sixteen farms participating in the Teagasc/Farmers Journal BETTER farm beef programme were used in this study. Fourteen herds were screened for the presence of BVD virus in 2010 using RT-PCR. In 13 herds, blood samples were collected from calves (2-14 days of age) in November 2011 - April 2012 to determine their passive immune status using the zinc sulphate turbidity (ZST) test, while in 12 herds, blood and faecal samples were taken in order to determine the level of exposure to gastrointestinal and hepatic helminths. Results The overall prevalence of BVD virus-positive cattle was 0.98% (range 0 - 3% per herd, range 0.6 - 3.0% per positive herd). Eighteen of the 82 calves (22%) sampled had ZST values less than 20 units (herd mean range 17.0 - 38.5 units) indicating a failure of passive transfer. The overall animal-level (herd-level) prevalence of liver fluke and rumen fluke infection in these herds was 40.5% (100%) and 20.8% (75%), respectively. Conclusions The potential costs associated with the presence of animals persistently infected with BVD virus through the increased use of antibiotics; the rate of failure of passive transfer of colostral immunoglobulins and the high prevalence of liver fluke infection in these herds highlight that some Irish suckler beef farms may not be realizing their economic potential due to a range of herd health issues. The use of farm-specific herd health plans should be further encouraged on Irish suckler beef farms. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify microRNAs associated with a serum antibody response to Mycoplasma bovis in beef cattle. Serum from sixteen beef calves was collected at three points: in summer after calves were born, in fall at weaning, and in the following spring. All sera collected in the summer were ELISA-negative for anti-M. bovis. By the fall, eight animals were seropositive for IgG (positive group), while eight remained negative (negative group). By spring, all animals in both groups were seropositive. MicroRNAs were extracted from sera and sequenced on the Illumina HiSeq next-generation sequencer. A total of 1,374,697 sequences mapped to microRNAs in the bovine genome. Of these, 82% of the sequences corresponded to 27 microRNAs, each represented by a minimum of 10,000 sequences. There was a statistically significant interaction between ELISA response and season for bta-miR-24-3p (P = 0.0268). All sera collected at the initial summer had a similar number of copies of this microRNA (P = 0.773). In the fall, the positive group had an increased number of copies when compared to the negative group (P = 0.021), and this grew more significant by the following spring (P = 0.0001). There were 21 microRNAs associated (P< 0.05) with season. These microRNAs could be evaluated further as candidates to potentially improve productivity in cattle. The microRNAs bta-let-7b, bta-miR- 24-3p, bta-miR- 92a, and bta-miR-423-5p, were significatly associated with ELISA status (P< 0.05). These microRNAs have been recognized as playing a role in the host defense against bacteria in humans, mice, and dairy cattle. Further studies are needed to establish if these microRNAs could be used as diagnostic marker or indicator of exposure, or whether intervention strategies could be developed as an alternative to antibiotics for controlling disease due to M. bovis. [ABSTRACT FROM AUTHOR]