Analysis of within-pen and between-pen fenceline temporal contact networks in confined feedlot cattle.

Though contact networks are important for describing the dynamics for disease transmission and intervention applications, individual animal contact and barriers between animal populations, such as fences, are not often utilized in the construction of these models. The objective of this study was to use contact network analysis to quantify contacts within two confined pens of feedlot cattle and the shared "fenceline" area between the pens at varying temporal resolutions and contact duration to better inform the construction of network-based disease transmission models for cattle within confined-housing systems. Two neighboring pens of feedlot steers were tagged with Real-Time Location System (RTLS) tags. Within-pen contacts were defined with a spatial threshold (SpTh) of 0.71 m and a minimum contact duration (MCD) of either 10 seconds (10 s), 30 seconds (30 s), or 60 seconds (60 s). For the fenceline network location readings were included within an area extending from 1 m on either side of the shared fence. "Fenceline" contacts could only occur between a steer from each pen. Static, undirected, weighted contact networks for within-pen networks and the between-pen network were generated for the full study duration and for daily (24-h), 6-h period, and hourly networks to better assess network heterogeneity. For the full study duration network, the two within-pen networks were densely homogenous. The within-pen networks showed more heterogeneity when smaller timescales (6-h period and hourly) were applied. When contacts were defined with a MCD of 30 s or 60 s, the total number of contacts seen in each network decreased, indicating that most of the contacts observed in our networks may have been transient passing contacts. Cosine similarity was moderate and stable across days for within pen networks. Of the 90 total tagged steers between the two pens, 86 steers (46 steers from Pen 2 and 40 steers from Pen 3) produced at least one contact across the shared fenceline. The total network density for the network created across the shared fenceline between the two pens was 17%, with few contacts at shorter timescales and for MCD of 30 s or 60 s. Overall, the contact networks created here from high-resolution spatial and temporal contact observation data provide estimates for a contact network within commercial US feedlot pens and the contact network created between two neighboring pens of cattle. These networks can be used to better inform pathogen transmission models on social contact networks.

Evaluation of predictive models to determine total morbidity outcome of feedlot cattle based on cohort-level feed delivery data during the first 15 days on feed.

Changes in feeding behavior and intake have been used to predict the onset of bovine respiratory disease in individual animals but have not been applied to cohort-level data. Correctly identifying high morbidity cohorts of cattle early in the feeding period could facilitate the administration of interventions to improve health and economic outcomes. The study objective was to determine the ability of feed delivery data from the first 15 days of feed to predict total feeding period morbidity. Data consisted of 518 cohorts (10 feedlots, 56,796 animals) of cattle of varying sex, age, arrival weight, and arrival time of year over a 2-year period. Overall cohort-level morbidity was classified into high (≥15% total morbidity) or low categories with 18.5% of cohorts having high morbidity. Five predictive models (advanced perceptron, decision forest, logistic regression, neural network, and boosted decision tree) were created to predict overall morbidity given cattle characteristics at arrival and feeding characteristics from the first 15 days. The dataset was split into training and testing subsets (75% and 25% of original, respectively), stratified by the outcome of interest. Predictive models were generated in Microsoft Azure using the training set and overall predictive performance was evaluated using the testing set. Performance in the testing set (n = 130) was measured based on final accuracy, sensitivity (Sn, the ability to accurately detect high morbidity cohorts), and specificity (Sp, the ability to accurately detect low morbidity cohorts). The decision forest had the highest Sp (97%) with the greatest ability to accurately identify low morbidity lots (103 of 106 identified correctly), but this model had low Sn (33%). The logistic regression and neural network had similar Sn (both 63%) and Sp (69% and 72%, respectively) with the best ability to correctly identify high morbidity cohorts (15 of 24 correctly identified). Predictor variables with the greatest importance in the predictive models included percent change in feed delivery between days and 4-day moving averages. The most frequent variable with a high level of importance among models was the percent change in feed delivered from d 2 to 3 after arrival. In conclusion, feed delivery data during the first 15 days on feed was a significant predictor of total cohort-level morbidity over the entire feeding period with changes in feed delivery providing important information.

Sources and reporting of oil spills and impacts on wildlife 1970-2018.

The extraction, transport, and consumption of hydrocarbons occur daily worldwide and can lead to environmental pollution and significant incidents of wildlife mortality. This review of literature and publicly available databases from 1970 to 2018 summarises records on oil spill incidents, sources of spills, and reported effects on wildlife. During this time period, millions of tonnes of oil were released from over 1700 acute oil spills, with only 312 (18%) reporting wildlife effects. The most numerous reported spill source was shipping. From this review, there are obvious global gaps in reporting of oil spills and recording of effects on wildlife. We recommend there is a global need for increased consistency of reporting and availability of data of oil spills, and wildlife impacts. This information is critical to preparedness and response procedures for industry (shipping and oil) and governments.

BIG DATA ANALYTICS AND PRECISION ANIMAL AGRICULTURE SYMPOSIUM: Data to decisions.

Big data are frequently used in many facets of business and agronomy to enhance knowledge needed to improve operational decisions. Livestock operations collect data of sufficient quantity to perform predictive analytics. Predictive analytics can be defined as a methodology and suite of data evaluation techniques to generate a prediction for specific target outcomes. The objective of this manuscript is to describe the process of using big data and the predictive analytic framework to create tools to drive decisions in livestock production, health, and welfare. The predictive analytic process involves selecting a target variable, managing the data, partitioning the data, then creating algorithms, refining algorithms, and finally comparing accuracy of the created classifiers. The partitioning of the datasets allows model building and refining to occur prior to testing the predictive accuracy of the model with naive data to evaluate overall accuracy. Many different classification algorithms are available for predictive use and testing multiple algorithms can lead to optimal results. Application of a systematic process for predictive analytics using data that is currently collected or that could be collected on livestock operations will facilitate precision animal management through enhanced livestock operational decisions.

A deterministic, dynamic systems model of cow-calf production: The effects of breeding replacement heifers before mature cows over a 10-year horizon.

Some cattle production experts believe that cow-calf producers should breed replacement heifers (nulliparous cows) before cows (primiparous and multiparous cows), sometimes referred to as providing a heifer lead time (tHL). Our objective was to model the effects different durations of tHL may have on measures of herd productivity, including the percent of the herd cycling before the end of the first 21 d of the breeding season (%C21), the percent of the herd pregnant at pregnancy diagnosis (%PPD), the distribution of pregnancy by 21-d breeding intervals, the kilograms of calf weaned per cow exposed (KPC), and the replacement percentage (%RH), using a deterministic, dynamic systems model of cow-calf production over a 10-yr horizon. We also wished to examine differences in the effect of tHL related to the primiparous duration of postpartum anestrus (dPPA). The study model examined 6 different dPPA for primiparous cows (60, 70, 80, 90, 100, or 110 d). The multiparous cow duration of postpartum anestrus was set to 60 d. The breeding season length for nulliparous cows was 63 d, as was the breeding season length for primiparous and multiparous cows. Nulliparous cows were modeled with a tHL of 0, 7, 14, 21, 28, 35, or 42 d. Results are reported for the final breeding season of the 10-yr horizon. Increasing tHL resulted in a greater %C21 for the herd and for primiparous cows. Length of tHL had minimal impact on the %PPD unless the dPPA was 80 d or greater. For a dPPA of 110 d, a 0 d tHL resulted in the herd having 88.1 %PPD. When tHL was 21 d, the %PPD increased to 93.0%. The KPC was 161.2 kg when the dPPA was 110 d and tHL was 0 d and improved to 183.2 kg when tHL was increased to 42 d. The %RH did not vary much unless the dPPA was 90 d or greater, but increasing tHL resulted in decreased %RH. Based on the model results, increasing tHL improves the production outcomes included in the analysis, but herds with dPPA of 90 d or greater had the greatest degree of improvement. For these herds, approximately two-thirds of the improvement in outcomes by increasing tHL from 0 d to 42 d was realized when tHL was 21 d. Costs are likely incurred when implementing tHL in a breeding management program, and an ideal tHL likely depends on the dPPA of the herd, the expected improvement in productivity, and the costs associated with increasing tHL. Determining the dPPA of a herd could help veterinarians and producers develop optimal herd management strategies.

A retrospective analysis of risk factors associated with bovine respiratory disease treatment failure in feedlot cattle.

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.

A deterministic, dynamic systems model of cow-calf production: The effects of the duration of postpartum anestrus on production parameters over a 10-year horizon.

The duration of postpartum anestrus (dPPA) is important to consider for reproductive performance and efficiency in cow-calf operations. We developed a deterministic, dynamic systems model of cow-calf production over a 10-yr horizon to model the effects that dPPA had on measures of herd productivity, including the percentage of cows cycling before the end of the first 21 d of the breeding season (%C21), the percentage of cows pregnant at pregnancy diagnosis (%PPD), the distribution of pregnancy by 21-d breeding intervals, the kilograms of calf weaned (KW), the kilograms of calf weaned per cow exposed (KPC), and the replacement percentage. A 1,000-animal herd was modeled, with the beginning and ending dates for a 63-d natural service breeding season being the same for eligible replacement heifers (nulliparous cows) and cows (primiparous and multiparous cows). Herds were simulated to have a multiparous cow dPPA of 50, 60, 70, or 80 d, with the dPPA for primiparous cows being set to 50, 60, 70, 80, 90, 100, or 110 d. Only combinations where the primiparous dPPA was greater than or equal to the multiparous dPPA were included, resulting in 22 model herds being simulated in the analysis. All other model parameters were held constant between simulations. In model season 10, the %C21 was 96.2% when the multiparous cow and primiparous cow dPPA was 50 d and was 48.3% when the multiparous cow and primiparous cow dPPA was 80 d. The %PPD in model season 10 for these same herds was 95.1% and 86.0%, respectively. The percentage of the herd becoming pregnant in the first 21 d of the breeding season also differed between these herds (61.8% and 31.3%, respectively). The 10-yr total KW was more than 275,000 kg greater for the herd with a 50-d multiparous cow and primiparous cow dPPA when compared with the herd with the 80-d multiparous and primiparous cow dPPA and had a model season 10 KPC of 180.8 kg compared with 151.4 kg for the longer dPPA. The model results show that both the multiparous cow and primiparous cow dPPA affect herd productivity outcomes and that a dPPA less than 60 d results in improved production outcomes relative to longer dPPA. Veterinarians and producers should consider determining the dPPA to aid in making management decisions to improve reproductive performance of cow-calf herds.

A mixed treatment comparison meta-analysis of metaphylaxis treatments for bovine respiratory disease in beef cattle.

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.

Measurement of distal limb sub-bandage pressure over 96 hours in horses.

REASONS FOR PERFORMING STUDY: Currently, there is no objective information quantifying pressures exerted by distal limb bandages. OBJECTIVES: To quantify the pressure exerted by each compression layer, a polo wrap (DLP), a compression bandage (DLC), and to measure the effect of time on sub-bandage pressure. STUDY DESIGN: Longitudinal observational experiment. METHODS: A DLC construct included a cotton roll compressed with brown gauze and elastic layers and the DLP construct included a pillow pad compressed by a cloth wrap. Dorsal and lateral sensors were placed on the mid-metacarpus. In healthy horses, sub-bandage pressures were recorded during application (n = 8) and at scheduled time points over the 24 (n = 9) and 96 h periods (n = 8). A generalised linear model was used to evaluate associations between pressure and sensor location, bandage type and time (P<0.05). RESULTS: For the DLC, dorsal and lateral sensor pressures were 187 mmHg (95% CI 185-189 mmHg) and 142 mmHg (95% CI 133-151 mmHg). Combined sensor pressure after application of the brown gauze was 80 mmHg (95% CI 75-85 mmHg) and rose to 165 mmHg (95% CI 160-170 mmHg) after the elastic layer. Combined pressure at the end of the 96 h period was 135 mmHg (95% CI 123-147 mmHg). For the DLP bandage, location but not time was significant. Combined pressures ranged between 75 mmHg (95% CI 53-97 mmHg) and 85 mmHg (95% CI 63-107 mmHg). CONCLUSIONS: Pressure distribution was not uniform. The DLP pressures were maintained for a 24 h period. The DLC maintained high pressures for 96 h, but a significant decrease in pressure occurred between 6 and 12 h. Providing there are no other reasons to change a bandage, a 4 day interval between bandages may be appropriate if maintaining distal limb compression is the principal indication.

Interpreting statistics from published research to answer clinical and management questions.

Appropriate statistical analysis is critical in interpreting results from published literature to answer clinical and management questions. Internal validity is an assessment of whether the study design and statistical analysis are appropriate for the hypotheses and study variables while controlling for bias and confounding. External validity is an assessment of the appropriateness of extrapolation of the study results to other populations. Knowledge about whether treatment or observation groups are truly different is unknown, but studies can be broadly categorized as exploratory or discovery, based on knowledge about previous research, biology, and study design, and this categorization affects interpretation. Confidence intervals, -values, prediction intervals, credible intervals, and other decision aids are used singly or in combination to provide evidence for the likelihood of a given model but can be interpreted only if the study is internally valid. These decision aids do not test for bias, study design, or the appropriateness of applying study results to other populations dissimilar to the population tested. The biologic and economic importance of the magnitude of difference between treatment groups or observation groups as estimated by the study data and statistical interpretation is important to consider in clinical and management decisions. Statistical results should be interpreted in light of the specific question and production system addressed, the study design, and knowledge about pertinent aspects of biology to appropriately aid decisions.

Pharmacokinetics and pharmacodynamics of gamithromycin in pulmonary epithelial lining fluid in naturally occurring bovine respiratory disease in multisource commingled feedlot cattle.

The objectives of this study were to determine (i) whether an association exists between individual pharmacokinetic parameters and treatment outcome when feeder cattle were diagnosed with bovine respiratory disease (BRD) and treated with gamithromycin (Zactran(®) ) at the label dose and (ii) whether there was a stronger association between treatment outcome and gamithromycin concentration in plasma or in the pulmonary epithelial lining fluid (PELF) effect compartment. The study design was a prospective, blinded, randomized clinical trial utilizing three groups of 60 (362-592 lb) steers/bulls randomly allocated within origin to sham injection or gamithromycin mass medication. Cattle were evaluated daily for signs of BRD by a veterinarian blinded to treatment. Animals meeting the BRD case definition were enrolled and allocated to a sample collection scheme consisting of samples for bacterial isolation (bronchoalveolar lavage fluid and nasopharyngeal swabs) and gamithromycin concentration determination (PELF and plasma). Gamithromycin susceptibility of M. haemolytica (n = 287) and P. multocida (n = 257) were determined using broth microdilution with frozen panels containing gamithromycin at concentrations from 0.03 to 16 µg/mL. A two-compartment plasma pharmacokinetic model with an additional compartment for gamithromycin in PELF was developed using rich data sets from published and unpublished studies. The sparse data from our study were then fit to this model using nonlinear mixed effects modeling to estimate individual parameter values. The resulting parameter estimates were used to simulate full time-concentration profiles for each animal in this study. These profiles were analyzed using noncompartmental methods so that PK/PD indices (AUC24 /MIC, AUC∞ /MIC, CMAX /MIC) could be calculated for plasma and PELF (also T>MIC) for each individual. The calculated PK/PD indices were indicative that for both M. haemolytica and P. multocida a higher drug exposure in terms of concentration, and duration of exposure relative to the MIC of the target pathogen, was favorable to a successful case outcome. A significant association was found between treatment success and PELF AUC0-24 /MIC for P. multocida. The calves in this study demonstrated an increased clearance and volume of distribution in plasma as compared to the healthy calves in two previously published reports. Ultimately, the findings from this study indicate that higher PK/PD indices were predictive of positive treatment outcomes.

Determination of value of bovine respiratory disease control using a remote early disease identification system compared with conventional methods of metaphylaxis and visual observations.

Mitigation of the deleterious effects of bovine respiratory disease (BRD) is an important issue in the cattle industry. Conventional management of calves at high risk for BRD often includes mass treatment with antimicrobials at arrival followed by visual observation for individual clinical cases. These methods have proven effective; however, control program efficacy is influenced by the accuracy of visual observation. A remote early disease identification (REDI) system has been described that monitors cattle behavior to identify potential BRD cases. The objective of this research was to compare health and performance outcomes using either traditional BRD control (visual observation and metaphylaxis) or REDI during a 60-d postarrival phase in high-risk beef calves. The randomized controlled clinical trial was performed in 8 replicates at 3 different facilities over a 19-mo period. In each replicate, a single load of calves was randomly allocated to receive either conventional management (CONV; total = 8) or REDI (total = 8) as the method for BRD control. Cattle were monitored with each diagnostic method for the first 30 d on feed and performance variables were collected until approximately 60 d after arrival. Statistical differences ( < 0.10) were not identified in common performance (ADG) or health (morbidity, first treatment success, and mortality risk) among the treatment groups. Calves in the REDI pens had a lower ( < 0.01) average number of days on feed at first treatment (9.1 ± 1.2 d) compared with CONV pens (15.8 ± 1.2 d). There were no statistical differences ( > 0.10) in risk of BRD treatment and REDI calves were not administered antimicrobials at arrival; therefore, REDI calves had a lower ( < 0.01) average number of doses of antimicrobials/calf (0.75 ± 0.1 doses) compared with CONV calves (1.67 ± 0.1 doses). In this trial, the REDI system was comparable to conventional management with the potential advantages of earlier BRD diagnosis and decreased use of antimicrobials. Further research should be performed to evaluate the longer-term impacts of the 2 systems.

Regression analysis to predict growth performance from dietary net energy in growing-finishing pigs.

Data from 41 trials with multiple energy levels (285 observations) were used in a meta-analysis to predict growth performance based on dietary NE concentration. Nutrient and energy concentrations in all diets were estimated using the NRC ingredient library. Predictor variables examined for best fit models using Akaike information criteria included linear and quadratic terms of NE, BW, CP, standardized ileal digestible (SID) Lys, crude fiber, NDF, ADF, fat, ash, and their interactions. The initial best fit models included interactions between NE and CP or SID Lys. After removal of the observations that fed SID Lys below the suggested requirement, these terms were no longer significant. Including dietary fat in the model with NE and BW significantly improved the G:F prediction model, indicating that NE may underestimate the influence of fat on G:F. The meta-analysis indicated that, as long as diets are adequate for other nutrients (i.e., Lys), dietary NE is adequate to predict changes in ADG across different dietary ingredients and conditions. The analysis indicates that ADG increases with increasing dietary NE and BW but decreases when BW is above 87 kg. The G:F ratio improves with increasing dietary NE and fat but decreases with increasing BW. The regression equations were then evaluated by comparing the actual and predicted performance of 543 finishing pigs in 2 trials fed 5 dietary treatments, included 3 different levels of NE by adding wheat middlings, soybean hulls, dried distillers grains with solubles (DDGS; 8 to 9% oil), or choice white grease (CWG) to a corn-soybean meal-based diet. Diets were 1) 30% DDGS, 20% wheat middlings, and 4 to 5% soybean hulls (low energy); 2) 20% wheat middlings and 4 to 5% soybean hulls (low energy); 3) a corn-soybean meal diet (medium energy); 4) diet 2 supplemented with 3.7% CWG to equalize the NE level to diet 3 (medium energy); and 5) a corn-soybean meal diet with 3.7% CWG (high energy). Only small differences were observed between predicted and observed values of ADG and G:F except for the low-energy diet containing the greatest fiber content (30% DDGS diet), where ADG and G:F were overpredicted by 3 to 6%. Therefore, the prediction equations provided a good estimation of the growth rate and feed efficiency of growing-finishing pigs fed different levels of dietary NE except for the pigs fed the low-energy diet containing the greatest fiber content.

A stochastic model to determine the economic value of changing diagnostic test characteristics for identification of cattle for treatment of bovine respiratory disease.

Bovine respiratory disease is an economically important syndrome in the beef industry, and diagnostic accuracy is important for optimal disease management. The objective of this study was to determine whether improving diagnostic sensitivity or specificity was of greater economic value at varied levels of respiratory disease prevalence by using Monte Carlo simulation. Existing literature was used to populate model distributions of published sensitivity, specificity, and performance (ADG, carcass weight, yield grade, quality grade, and mortality risk) differences among calves based on clinical respiratory disease status. Data from multiple cattle feeding operations were used to generate true ranges of respiratory disease prevalence and associated mortality. Input variables were combined into a single model that calculated estimated net returns for animals by diagnostic category (true positive, false positive, false negative, and true negative) based on the prevalence, sensitivity, and specificity for each iteration. Net returns for each diagnostic category were multiplied by the proportion of animals in each diagnostic category to determine group profitability. Apparent prevalence was categorized into low (<15%) and high (≥15%) groups. For both apparent prevalence categories, increasing specificity created more rapid, positive change in net returns than increasing sensitivity. Improvement of diagnostic specificity, perhaps through a confirmatory test interpreted in series or pen-level diagnostics, can increase diagnostic value more than improving sensitivity. Mortality risk was the primary driver for net returns. The results from this study are important for determining future research priorities to analyze diagnostic techniques for bovine respiratory disease and provide a novel way for modeling diagnostic tests.

Structured literature review of responses of cattle to viral and bacterial pathogens causing bovine respiratory disease complex.

Bovine respiratory disease (BRD) is an economically important disease of cattle and continues to be an intensely studied topic. However, literature summarizing the time between pathogen exposure and clinical signs, shedding, and seroconversion is minimal. A structured literature review of the published literature was performed to determine cattle responses (time from pathogen exposure to clinical signs, shedding, and seroconversion) in challenge models using common BRD viral and bacterial pathogens. After review a descriptive analysis of published studies using common BRD pathogen challenge studies was performed. Inclusion criteria were single pathogen challenge studies with no treatment or vaccination evaluating outcomes of interest: clinical signs, shedding, and seroconversion. Pathogens of interest included: bovine viral diarrhea virus (BVDV), bovine herpesvirus type 1 (BHV-1), parainfluenza-3 virus, bovine respiratory syncytial virus, Mannheimia haemolytica, Mycoplasma bovis, Pastuerella multocida, and Histophilus somni. Thirty-five studies and 64 trials were included for analysis. The median days to the resolution of clinical signs after BVDV challenge was 15 and shedding was not detected on day 12 postchallenge. Resolution of BHV-1 shedding resolved on day 12 and clinical signs on day 12 postchallenge. Bovine respiratory syncytial virus ceased shedding on day 9 and median time to resolution of clinical signs was on day 12 postchallenge. M. haemolytica resolved clinical signs 8 days postchallenge. This literature review and descriptive analysis can serve as a resource to assist in designing challenge model studies and potentially aid in estimation of duration of clinical disease and shedding after natural pathogen exposure.

Genome-wide QTL mapping of saltwater tolerance in sibling species of Anopheles (malaria vector) mosquitoes.

Although freshwater (FW) is the ancestral habitat for larval mosquitoes, multiple species independently evolved the ability to survive in saltwater (SW). Here, we use quantitative trait locus (QTL) mapping to investigate the genetic architecture of osmoregulation in Anopheles mosquitoes, vectors of human malaria. We analyzed 1134 backcross progeny from a cross between the obligate FW species An. coluzzii, and its closely related euryhaline sibling species An. merus. Tests of 2387 markers with Bayesian interval mapping and machine learning (random forests) yielded six genomic regions associated with SW tolerance. Overlap in QTL regions from both approaches enhances confidence in QTL identification. Evidence exists for synergistic as well as disruptive epistasis among loci. Intriguingly, one QTL region containing ion transporters spans the 2Rop chromosomal inversion that distinguishes these species. Rather than a simple trait controlled by one or a few loci, our data are most consistent with a complex, polygenic mode of inheritance.

Comparison of sub-bandage pressures achieved by 3 abdominal bandaging techniques in horses.

REASONS FOR PERFORMING STUDY: Clinicians frequently place post operative abdominal bandages on horses undergoing laparotomies. Presently, no information exists on the amount of incisional support provided by these bandages. Determination of sub-bandage pressure provides a means of comparing the ability of different bandages to support incisions. OBJECTIVES: Determination of sub-bandage pressure over a 24 h period using 3 bandaging techniques. STUDY DESIGN: A randomised, crossover design using 9 healthy horses. METHODS: Horses were randomly assigned to a treatment regimen consisting of placement of 3 abdominal bandage types, namely an elastic bandage (ELA), the CM(TM) Hernia Heal Belt (CM) or a nylon binder (NYL). The sub-bandage pressures for each bandage were measured with the Picopress® compression-measuring system at 0, 2, 4, 6, 8, 12, 16, 20 and 24 h after application. RESULTS: No time and treatment interactions were observed, and bandage pressures were maintained within each treatment group over the 24 h period. Mean sub-bandage pressures were different between all treatment groups (P < 0.001) at 39 (95% confidence interval, 36.7-40.5 mmHg), 25 (95% confidence interval, 23.9-27.7 mmHg) and 5 mmHg (95% confidence interval, 4.1-7.8 mmHg) for CM, ELA and NYL bandages, respectively. Horses were more likely to lie down with the CM (P = 0.02) and ELA treatments (P = 0.0002) when compared with the NYL treatment. The ELA bandages were more likely to displace caudally compared with both CM and NYL bandages. CONCLUSIONS: The CM bandage was superior to both ELA and NYL bandages with regard to measured sub-bandage pressure over the 24 h period. The clinical significance of the differences in sub-bandage pressure between treatments cannot be determined by this study.

Impact of oral meloxicam administered alone or in combination with gabapentin on experimentally induced lameness in beef calves.

This study examined the pharmacokinetics and analgesic effect of oral meloxicam (MEL) administered alone or in combination with gabapentin (GABA) in an experimental bovine lameness model. Eighteen male British × Continental beef calves aged 4 to 6 mo and weighing 297 to 392 kg were randomly assigned to receive either 1) 0.5 mg/kg lactose monohydrate placebo (PLBO; n = 6), 2) 0.5 mg/kg MEL (n = 6), or 3) 0.5 mg/kg MEL combined with 15 mg/kg GABA (MEL-GABA; n = 6) once daily for 4 d. The first treatment was administered 4 h after a chemical synovitis/arthritis was induced with injection of 15 mg amphotericin B into the left hind lateral distal interphalangeal joint. Changes in activity were evaluated continuously with pedometers. Contact force, contact area, contact pressure, impulse, and stride length were recorded once daily with a pressure mat and visual lameness scores were determined by a masked observer using a 5-point scale. Cortisol and drug concentrations were determined daily by immunoassay and HPLC-mass spectrometry, respectively. Outcomes were compared statistically using a random effects mixed model and analysis of covariance. There was a positive association between lameness scores and serum cortisol concentrations (P = 0.02) and a negative association between lameness score and step count (P < 0.0001), total force (P = 0.001), force applied to the lateral claw (P = 0.02), contact pressure (P = 0.005), and impulse of the lateral claw (P = 0.01). Step count was greater in MEL calves compared with PLBO (P = 0.008) and MEL-GABA (P = 0.04) calves. Impulse was greater in the MEL-GABA calves compared with the PLBO calves (P = 0.03). There was an inverse relationship between plasma MEL concentrations and lameness score (P = 0.02) and a positive association between MEL concentrations and force applied to the lateral claw (P = 0.03), total contact pressure (P = 0.03), and impulse on the lateral claw (P = 0.02). There was a tendency towards a positive association between GABA concentrations, total impulse, and impulse on the lateral claw (P = 0.08) and a negative associate between GABA concentrations and step count (P = 0.08). The results of this study suggest that MEL administered alone or in combination with GABA reduced the severity of lameness in calves following induction of lameness with amphotericin B. These findings have implications for developing analgesic protocols in lame calves that address both production and welfare concerns.

Pulmonary lesions and clinical disease response to Mannheimia haemolytica challenge 10 days following administration of tildipirosin or tulathromycin.

This clinical trial evaluated the impact of metaphylactic antimicrobial administration 10 d before experimental inoculation with Mannheimia haemolytica (MH) to mitigate pulmonary lesions. Thirty-three crossbreed heifers were procured as a single group and were randomly allocated to 1 of 3 blocks and to treatment, tildipirosin (ZUP; 4 mg/kg) or tulathromycin (DRX; 2.5 mg/kg) or saline (SAL; 1 mL/45.5 kg), within block on arrival at Kansas State University. All trial procedures were staggered by 7-d intervals for each block, resulting in all animals within a block receiving treatment, challenge, and necropsy on the same dates. Heifers within each block received an endoscopic MH challenge 10 d following treatment administration (d 0) and were housed in individual indoor stalls for 3 d postchallenge. Clinical illness scores (CIS), respiration quality scores, appetite scores, and injection site reactions were recorded on all animals from d 0 through d 13. Rectal temperatures were measured once daily on all animals from d 8 through d 13. Heifers were necropsied, and lung lesions were evaluated on d 13. Lung lesion data were evaluated using nonparametric methods (Kruskall-Wallis), and standard least squares models were used to evaluate the remaining variables. The pulmonary lesion scores (percentage of affected lung) ranged from 3.3% to 39.8% for all heifers with 92% (11/12) of ZUP-treated heifers having <10% lesions. Tildipirosin-treated heifers had lower (P < 0.05) lung lesion scores when compared with DRX- and SAL-treated heifers. Lung weight expressed as a percentage of BW was lower (P < 0.05) in ZUP heifers compared to DRX- and SAL-treated heifers. The probability of receiving abnormal CIS, appetite scores, and respiratory scores was lower (P < 0.05) in ZUP-treated heifers compared to DRX- and SAL-treated animals. This study showed that heifers treated with tildipirosin 10 d before MH challenge have less pulmonary damage and fewer clinical signs of illness compared to heifers treated with DRX or SAL.

Effect of Mannheimia haemolytica pneumonia on behavior and physiologic responses of calves during high ambient environmental temperatures.

The objective of this study was to determine the effect of pneumonia during conditions of high (maximum ≥ 32°C) ambient temperatures on physiological and behavioral responses of calves. Eighteen black beef heifers averaging 240 kg were blocked by BW and randomly assigned to 1 of 2 treatment groups: 1) pneumonia induced by bronchoselective endoscopic inoculation with Mannheimia haemolytica (MH; n = 10) and 2) noninoculated controls (CN; n = 8). Nasal passage and rectal temperatures were measured every 2 h for 24 h after challenge and then twice daily for 9 d. Accelerometers, pedometers, and positioning devices monitored cattle behavior within the pen for 9 d after challenge. Blood samples were collected on trial d 0, 0.5, 1, 2, 3, 7, and 9 and were analyzed to determine the concentration of substance P, cortisol, haptoglobin, and metalloproteinase. All calves in the MH group were euthanized and necropsied on trial d 9. All MH calves became clinically ill postchallenge. A treatment × time interaction (P < 0.05) was evident for nasal and rectal temperatures, behavior, weight, and blood analysis. Rectal temperatures in MH were higher (P < 0.01) than CN during the period from 6 to 24 h after challenge. Conversely, nasal passage temperatures were less in MH calves compared with CN at 12 to 22 h after challenge. Calves in MH spent less time at the grain bunk, less time at the hay feeder, and more time lying down during the early pneumonia period compared with CN calves. Also, MH calves had significantly greater concentrations of blood biomarkers of pain (substance P) on d 0.5 (P < 0.01); stress (cortisol) on d 0.5 and 1 (P < 0.01); haptoglobin on d 0.5, 1, 2, 3, 7 (P < 0.01); and metalloproteinase on d 1, 2, and 3 (P < 0.01) compared with CN calves. At necropsy, all MH calves had right cranioventral bronchopneumonia (median lung lesions = 6.8%). Mannheimia haemolytica pneumonia caused significantly more changes in behavior and increased biomarkers during high (maximum ≥32°C) ambient temperatures compared with control calves. The results of this study may guide research in the development of objective assessment tools for management of cattle affected with bovine respiratory disease during extreme summer conditions.