Associations of various physical and blood analysis variables with experimentally induced Mycoplasma bovis pneumonia in calves

Association of Bovine Respiratory Disease during the Pre-Weaning Period with Blood Cell Counts and Circulating Concentration of Metabolites, Minerals, and Acute Phase Proteins in Dairy Calves Transported to a Calf Raising Facility

Our objective was to investigate the association of bovine respiratory disease (BRD) occurring within the first 56 days of life with blood cell counts and the circulating concentration of metabolites, minerals, and acute phase proteins throughout the pre-weaning period in dairy calves transported to a heifer raising facility within their first week of life. Data from 305 calves transported from dairies in Minnesota to a calf raising facility in New Mexico within their first four days of life were used in this retrospective cohort study. Blood samples were collected at 7, 17, 34, and 56 days of life for the analysis of blood cell counts, biochemistry, and the concentration of acute phase proteins. Blood urea nitrogen, albumin, GLDH, CK, P, Na, K, Cl, Zn, Hp, SAA, and monocyte counts were associated with BRD status throughout or at least at one of the time points evaluated in this study. In conclusion, several hematological variables were associated with BRD status in dairy calves that underwent transportation stress in early life.

Investigation of Vitamin a and 25(OH)D3 Levels in Cattle with Pneumonia Detected Mycoplasma bovis

This study investigated the presence of Mycoplasma bovis in nasal swabs taken from cattle with pneumonia, to reveal the clinical and biochemical findings of positive animals, and determine the levels of vitamin A and 25(OH)D3. In the study were included 103 infected cattle and 10 healthy cattle, all aged 1-4 years, as the control group. Quantitative clinical evaluations and clinical examinations were performed on each animal, and 5 ml blood samples and nasal swabs were taken. Serum biochemistry, vitamin A and 25(OH)D3 levels were determined in both positive and control samples. The clinical signs were identified by qualitative scoring in M. bovis positive animals. Regarding the clinical findings, respiratory frequency, heart rate, and rectal temperature were significantly higher in positive than control group animals (p<0.001). Regarding the biochemistry findings, albumin (ALB) and glucose (GLU) levels were lower in cattle infected with M. bovis (p<0.001) whereas total protein (TP) and alkaline phosphatase (ALP) levels were higher (p<0.001). While serum 25(OH)D3 levels were lower in infected animals (p<0.001), there was no significant difference (p>0.05) in serum vitamin A levels. In this study, clinical findings in cattle naturally infected with M. bovis were expressed qualitatively and quantitatively. In addition, it has been revealed that the disease does not only cause lung involvement, but also causes changes in biochemical and vitamin levels. Although these parameters cannot be used as a biomarker in the diagnosis of pneumonia, they are thought to provide benefits in terms of diagnosis, treatment and prophylaxis in practice.

Thermography for disease detection in livestock: A scoping review

Infra-red thermography (IRT) offers potential opportunities as a tool for disease detection in livestock. Despite considerable research in this area, there are no common standards or protocols for managing IRT parameters in animal disease detection research. In this review, we investigate parameters that are essential to the progression of this tool and make recommendations for their use based on the literature found and the veterinary thermography guidelines from the American Academy of Thermology. We analyzed a defined set of 109 articles concerned with the use of IRT in livestock related to disease and from these articles, parameters for accurate IRT were identified and sorted into the fields of camera-, animal- or environment-related categories to assess the practices of each article in reporting parameters. This review demonstrates the inconsistencies in practice across peer-reviewed articles and reveals that some important parameters are completely unreported while others are incorrectly captured and/or under-represented in the literature. Further to this, our review highlights the lack of measured emissivity values for live animals in multiple species. We present guidelines for the standards of parameters that should be used and reported in future experiments and discuss potential opportunities and challenges associated with using IRT for disease detection in livestock.

Prevalence of Mycoplasma bovis Infection in Calves and Dairy Cows in Western Australia

Simple Summary

Mycoplasma bovis is an emerging pathogen of economic and welfare concern for both adult and young cattle. A study was conducted to determine the prevalence of M. bovis in adult cows and calves in the southwest region of Western Australia. Nasal swabs and blood samples were collected from the animals and bulk tank milk samples were assessed for both seroprevalence and active infections of M. bovis infections in adult cows and calves. The study recorded a high seroprevalence of M. bovis in 699 apparently healthy adult lactating cows and 495 young calves on 29 dairy farms. The herd-level seroprevalence was also detected as being higher in both adult lactating cows and calves. No current active infections were recorded on the farms. The female calves and pure Holstein–Friesian animals were found to be twice as likely to be seropositive for M. bovis compared to male calves and the Holstein–Friesian crossbred calves. The high seroprevalence of M. bovis in both adult and young cattle in the southwest dairy farms of Western Australia warrants more effective farm biosecurity measures and further evaluation of the current prevention and management measures practiced on the farms.

Abstract

Mycoplasma bovis (M. bovis) can cause a multitude of diseases in cattle, with detrimental effects on the farm economy and the welfare of both adult and young cattle. The objective of this study was to determine the prevalence of M. bovis in adult cows and calves in the south-west region of Western Australia. A cross-sectional study was conducted on 29 dairy farms with 699 apparently healthy adult lactating cows and 495 young calves during 2019–2020. Nasal swabs and blood samples collected from the animals and bulk tank milk (BTM) samples were assessed for M. bovis-specific proteins and antibodies by using polymerase chain reaction (PCR) and Mycoplasma immunogenic lipase A- Enzyme-Linked Immune Sorbent Assay (MilA ELISA). A seroprevalence of 42.5% (95% CI: 38.9–46.2) and 61% (95% CI: 56.6–65.2) was found in adult lactating cows and calves, respectively. The herd-level seroprevalence of M. bovis ranged from 4% (95% CI: 07–19.5) to 92% (95% CI: 75.0–97.8) in adult lactating cows and 25% (95% CI: 10.2–49.5) to 87% (95% CI: 67.9–95.5) for calves in these farms. None of the BTM and nasal swab samples were positive for M. bovis, indicating an absence of any current active infections on the farms. The female calves and pure Holstein–Friesian animals are twice as likely to be seropositive for M. bovis compared to male calves (OR 2.4; 95% CI: 1.7–3.5) and Holstein–Friesian crossbred calves (OR 2.4; 95% CI: 1.7–3.5). The high seroprevalence in both adult and young cattle in the southwest dairy farms of Western Australia warrants more effective farm biosecurity measures and further evaluation of the current prevention and management measures practiced on the farms.

Hematological and immunological responses to naturally occurring bovine respiratory disease in newly received beef calves in a commercial stocker farm

The objective was to determine temporal changes in hematological and immune parameters in response to naturally occurring bovine respiratory disease (BRD) in commercially managed stocker calves. Forty newly weaned beef steers purchased from auction markets were housed at a commercial stocker operation in Crossville, TN. Blood samples, rectal temperature, and thoracic ultrasonography (TUS; 1: normal to 3: severe) were collected on days 0, 7, 14, and 21. Castration status (FC: freshly castrated; PC: previously castrated) was determined on arrival based on presence of a fresh castration site at the scrotum. Calves received antibiotics for BRD based on clinical severity scoring (CSS; 0: moribund, 4: moribund) and rectal temperature. Complete blood counts (CBC) were performed. Calves were categorized based on the number of treatments (NumTrt) received (0x, 1x, and 2x). Temporal variations in CBC and immune parameters were analyzed using mixed model repeated measure ANOVA (Proc GLIMMIX; SAS 9.4). Variation of CBCs and immune parameters based on TUS was determined using mixed model ANOVA. There was a NumTrt by day interaction effect on the responses of white blood cells (WBC) (P = 0.04) and haptoglobin (HPT) (P = 0.04). On day 21, WBC were greater in the 2x NumTrt group than other groups, but there were no differences in WBC between NumTrt levels on other days. Haptoglobin was greater in the 2x group on days 14 and 21 than 0x or 1x. Red blood cells (RBC) (P = 0.02) and WBC (P = 0.04) differed between FC and PC groups, and lower RBC and WBC were observed in the FC group. A castration status × day effect for mean corpuscular volume (MCV; P = 0.04) was observed where FC group had higher MCV at days 14 and 21 than the PC group. Tumor necrosis factor-α differed based on NumTrt (P = 0.03) and higher concentrations were found in 2x group. We observed a day effect for IL-1β (P = 0.009) and TNF-α (P = 0.001). Significant effect of TUS on HPT at day 14 (P = 0.0004) and day 21 (P = 0.002) was observed. Combining HPT and platelet explained 15% of the variability in treatment status on a given day, whereas HPT and hemoglobin explained 10% of the variability in lung consolidation status. Although hematological and immunological parameters varied largely in our study, the potential of combining HPT with hematological variables should be studied further. Results from this study would help in understanding temporal changes in CBC and immune parameters in newly received stocker cattle.

Assessment of bovine respiratory disease progression in calves challenged with bovine herpesvirus 1 and Mannheimia haemolytica using point-of-care and laboratory-based blood leukocyte differential assays

Blood leukocyte differentials can be useful for understanding changes associated with bovine respiratory disease (BRD) progression. By improving turnaround time, point-of-care leukocyte differential assays (PCLD) may provide logistical advantages to laboratory-based assays. Our objective was to assess BRD progression in steers challenged with bovine herpesvirus 1 and Mannheimia haemolytica using point-of-care and laboratory-based blood leukocyte differentials. Thirty Holstein steers (average body weight of 211 kg + 2.4 kg) were inoculated intranasally on day 0 with bovine herpesvirus 1 and intrabronchially on day 6 with Mannheimia haemolytica. Blood leukocytes differentials were measured using both assays from study days 0 to 13. Linear mixed models were fitted to evaluate the associations between: (1) the type of assay (laboratory-based or PCLD) with respect to leukocyte, lymphocyte, and neutrophil concentrations; (2) study day with cell concentrations; and (3) cell concentrations with lung consolidation measured at necropsy. Point-of-care leukocyte, lymphocyte, and neutrophil concentrations were significantly associated (P < 0.05) with the respective cell concentrations obtained from the laboratory-based leukocyte differential. Cell concentrations reported by both assays differed significantly (P < 0.05) over time, indicating shifts from healthy to viral and bacterial disease states. Lymphocyte concentrations, lymphocyte/neutrophil ratios obtained from both assays, and band neutrophil concentrations from the laboratory-based assay were significantly associated (P < 0.05) with lung consolidation, enhancing assessments of disease severity. The PCLD may be a useful alternative to assess BRD progression when laboratory-based leukocyte differentials are impractical.

Comparison of culture and a multiplex probe PCR for identifying Mycoplasma species in bovine milk, semen and swab samples

Mycoplasma spp. are a major cause of mastitis, arthritis and pneumonia in cattle, and have been associated with reproductive disorders in cows. While culture is the traditional method of identification the use of PCR has become more common. Several investigators have developed PCR protocols to detect M. bovis in milk, yet few studies have evaluated other sample types or other important Mycoplasma species. Therefore the objective of this study was to develop a multiplex PCR assay to detect M. bovis, M. californicum and M. bovigenitalium, and evaluate its analytical performance against traditional culture of bovine milk, semen and swab samples. The PCR specificity was determined and the limit of detection evaluated in spiked milk, semen and swabs. The PCR was then compared to culture on 474 field samples from individual milk, bulk tank milk (BTM), semen and swab (vaginal, preputial, nose and eye) samples. Specificity analysis produced appropriate amplification for all M. bovis, M. californicum and M. bovigenitalium isolates. Amplification was not seen for any of the other Mollicutes or eubacterial isolates. The limit of detection of the PCR was best in milk, followed by semen and swabs. When all three Mycoplasma species were present in a sample, the limit of detection increased. When comparing culture and PCR, overall there was no significant difference in the proportion of culture and PCR positive samples. Culture could detect significantly more positive swab samples. No significant differences were identified for semen, individual milk or BTM samples. PCR identified five samples with two species present. Culture followed by 16S-23S rRNA sequencing did not enable identification of more than one species. Therefore, the superior method for identification of M. bovis, M. californicum and M. bovigenitalium may be dependent on the sample type being analysed, and whether the identification of multiple target species is required.

Bayesian evaluation of clinical diagnostic test characteristics of visual observations and remote monitoring to diagnose bovine respiratory disease in beef calves

Accurate diagnosis of bovine respiratory disease (BRD) in beef cattle is a critical facet of therapeutic programs through promotion of prompt treatment of diseased calves in concert with judicious use of antimicrobials. Despite the known inaccuracies, visual observation (VO) of clinical signs is the conventional diagnostic modality for BRD diagnosis. Objective methods of remotely monitoring cattle wellness could improve diagnostic accuracy; however, little information exists describing the accuracy of this method compared to traditional techniques. The objective of this research is to employ Bayesian methodology to elicit diagnostic characteristics of conventional VO compared to remote early disease identification (REDI) to diagnose BRD. Data from previous literature on the accuracy of VO were combined with trial data consisting of direct comparison between VO and REDI for BRD in two populations. No true gold standard diagnostic test exists for BRD; therefore, estimates of diagnostic characteristics of each test were generated using Bayesian latent class analysis. Results indicate a 90.0% probability that the sensitivity of REDI (median 81.3%; 95% probability interval [PI]: 55.5, 95.8) was higher than VO sensitivity (64.5%; PI: 57.9, 70.8). The specificity of REDI (median 92.9%; PI: 88.2, 96.9) was also higher compared to VO (median 69.1%; PI: 66.3, 71.8). The differences in sensitivity and specificity resulted in REDI exhibiting higher positive and negative predictive values in both high (41.3%) and low (2.6%) prevalence situations. This research illustrates the potential of remote cattle monitoring to augment conventional methods of BRD diagnosis resulting in more accurate identification of diseased cattle.

Feeding behavior as an early predictor of bovine respiratory disease in North American feedlot systems

Bovine respiratory disease (BRD), which can cause substantial losses for feedlot operations, is often difficult to detect based solely on visual observations. The objectives of the current study were to determine a BRD case identification based on clinical and laboratory parameters and assess the value of feeding behavior for early detection of BRD. Auction-derived, mixed-breed beef steers (n = 213) with an average arrival weight of 294 kg were placed at a southern Alberta commercial feedlot equipped with an automated feed bunk monitoring system. Feeding behavior was recorded continuously (1-s intervals) for 5 wk after arrival and summarized into meals. Meals were defined as feeding events that were interrupted by less than 300 s nonfeeding. Meal intake (g) and meal time (min) were further summarized into daily mean, minimum, maximum, and sum and, together with frequency of meals per day, were fit into a discrete survival time analysis with a conditional log-log link. Feedlot staff visually evaluated (pen-checked) health status twice daily. Within 35 d after arrival, 76% (n = 165) of the steers had 1 or more clinical signs of BRD (reluctance to move, crusted nose, nasal or ocular discharge, drooped ears or head, and gaunt appearance). Whereas 41 blood samples could not be processed due to immediate freezing, for 124 of these steers, complete and differential blood cell count, total serum protein, plasma fibrinogen, serum concentration of haptoglobin (HP), and serum amyloid A (SAA) were determined. The disease definition for BRD was a rectal temperature ≥ 40.0°C, at least 2 clinical signs of BRD, and HP > 0.15 mg/mL. It was noteworthy that 94% of the 124 steers identified by the feedlot staff with clinical signs of BRD had HP > 0.15 mg/mL. An increase in mean meal intake, frequency, and mean inter-meal interval was associated with a decreased hazard for developing BRD 7 d before visual identification (P < 0.001). Furthermore, increased mean mealtime, frequency, and mean inter-meal interval were associated with a decreased BRD hazard up to 7 d before feedlot staff noticed clinical symptoms (P < 0.001). In conclusion, mean intake per meal as well as mean meal time and frequency of meals could be used to predict the hazard of BRD in feedlot cattle 7 d before visual detection and could be considered in commercial feedlot settings once a predictive algorithm has been developed.

Haematological and blood biochemical alterations associated with respiratory disease in calves

Respiratory diseases of cattle, particularly in young animals, represent the most important health and economic problem of cattle rearing. The aim of the present study was to evaluate the changes of selected blood indices in 25 calves aged 2–9 months suffering from etiologically undifferentiated chronic respiratory diseases. Blood samples were analysed for haematological indices and selected serum biochemistry variables. The results found in sick animals were compared with results from 25 healthy animals of the same age, housing and feeding system. Significant differences in means between the groups of clinically healthy and sick calves were found in 13 out of 24 evaluated indicators. In sick animals we found significantly higher mean concentrations of haemoglobin and total number of white blood cells (P < 0.05 and P < 0.01, respectively), as well as higher mean activity of AST and LDH (P < 0.01), concentrations of total proteins and total immunoglobulins (P < 0.001). Significantly lower mean values were recorded in the serum concentrations of albumin, creatinine and glucose (P < 0.001), as well as in the concentration of Mg (P < 0.01), P (P < 0.001), Fe and Zn (P < 0.05). The presented results suggest the effect of respiratory diseases in calves on several changes of haematological and selected serum biochemical indicators. They indicate that respiratory diseases did not lead only to direct disturbance of gas exchange and acid-base balance, but they also indirectly affect some other variables of blood biochemistry.