Use of Thoracic Ultrasonography to Improve Disease Detection in Experimental BRD Infection

Bovine respiratory disease (BRD) is caused by complex interactions between viral and bacterial pathogens, host immune status, and environmental stressors. In both clinical and research settings, current methods for detecting BRD in calves commonly focus on visual indicators such as attitude, nasal discharge, and cough, in addition to vital signs such as rectal temperature and respiration rate. Recently, thoracic ultrasonography (TUS) has become more commonly used in clinical settings, in addition to physical examination to diagnose BRD. To assess the value of performing TUS during experimental BRD infection, 32 calves were challenged with bovine respiratory syncytial virus, to mimic a viral infection, and 30 calves were infected with Mannheimia haemolytica, to mimic a bacterial infection. TUS was performed at regular intervals using a standardized method and scoring system in addition to daily clinical scoring. Although overall correlations between clinical scores and TUS scores were generally weak (maximum R2 = 0.3212), TUS identified calves with abnormal lung pathology that would have otherwise been misclassified on the basis of clinical scoring alone, both on arrival and throughout the studies. In addition, TUS had an increased correlation with gross lung pathology on necropsy (maximum R2 = 0.5903), as compared to clinical scoring (maximum R2 = 0.3352). Our results suggest that TUS can provide additional information on calf health at enrollment and throughout a study and may provide an alternative to terminal studies, due to the high correlation with lung pathology at necropsy.

The Effect of Contract-Rearing on the Health Status of Replacement Dairy Heifers

The aim of this study was to compare the health status of contract- vs. conventionally reared replacement dairy heifers over a 2-year period. A total of 120 dairy farmers were enrolled in the study in spring 2018: 55 farmers were rearing their own heifers (control farmers; CFs), and 65 were sending heifers to a contract-rearing farm (source dairy farmers; SDFs). Between spring 2018 and autumn 2019, approximately 5500 replacement heifers from these farms were monitored for signs of ill health during four farm visits using a modified version of the Wisconsin calf health scoring system. Additionally, faecal and nasal swabs were taken from a proportion of heifers with clinical signs of diarrhoea and respiratory disease to determine the associated aetiological agents. Results indicate few differences in the health status and pathogen exposure status of home-reared versus contract-reared heifers. Additionally, the number of source dairy farms represented and commingling of heifers from multiple origins at the rearing unit were not associated with an increased incidence of respiratory disease or diarrhoea among contract-reared heifers. It was concluded that contract-rearing did not result in adverse health outcomes for replacement dairy heifers. This is the first study to demonstrate this finding in a robust, longitudinal, herd-level population study.

A Systematic Review of Automatic Health Monitoring in Calves: Glimpsing the Future From Current Practice

Infectious diseases, particularly bovine respiratory disease (BRD) and neonatal calf diarrhea (NCD), are prevalent in calves. Efficient health-monitoring tools to identify such diseases on time are lacking. Common practice (i.e., health checks) often identifies sick calves at a late stage of disease or not at all. Sensor technology enables the automatic and continuous monitoring of calf physiology or behavior, potentially offering timely and precise detection of sick calves. A systematic overview of automated disease detection in calves is still lacking. The objectives of this literature review were hence: to investigate previously applied sensor validation methods used in the context of calf health, to identify sensors used on calves, the parameters these sensors monitor, and the statistical tools applied to identify diseases, to explore potential research gaps and to point to future research opportunities. To achieve these objectives, systematic literature searches were conducted. We defined four stages in the development of health-monitoring systems: (1) sensor technique, (2) data interpretation, (3) information integration, and (4) decision support. Fifty-four articles were included (stage one: 26; stage two: 19; stage three: 9; and stage four: 0). Common parameters that assess the performance of these systems are sensitivity, specificity, accuracy, precision, and negative predictive value. Gold standards that typically assess these parameters include manual measurement and manual health-assessment protocols. At stage one, automatic feeding stations, accelerometers, infrared thermography cameras, microphones, and 3-D cameras are accurate in screening behavior and physiology in calves. At stage two, changes in feeding behaviors, lying, activity, or body temperature corresponded to changes in health status, and point to health issues earlier than manual health checks. At stage three, accelerometers, thermometers, and automatic feeding stations have been integrated into one system that was shown to be able to successfully detect diseases in calves, including BRD and NCD. We discuss these findings, look into potentials at stage four, and touch upon the topic of resilience, whereby health-monitoring system might be used to detect low resilience (i.e., prone to disease but clinically healthy calves), promoting further improvements in calf health and welfare.

103 The Economics and Role of Beef X Dairy Calves in the Beef Supply Chain

Utilizing beef genetics in dairy herds to produce terminal beef x dairy (BXD) crosses is a growing trend in the U.S. dairy industry. It has been estimated that more than two million U.S. BXD calves were born in 2020, which is a practice that is expected to continue to grow throughout the foreseeable future. While not a new concept, the widespread adoption, scale, and strategies currently being used to produce BXD calves have recently received considerable industry attention. Although the increased duration of feeding exposes BXD feeders to increased price and production risks when compared to straightbred beef cattle, these risks are met with several potential benefits. A prime example of such benefits includes a consistent supply of uniform, traceable feeder cattle that are easily age and source verified, that also serve as ideal candidates for enrollment in or development of other value-added marketing programs. Current demand, as indicated by newborn calf prices, suggests that the industry perceives BXD calves to be superior when compared to their straightbred dairy breed contemporaries, and at times, suggests that they may be overvalued. Sustaining such demand will require BXD calves to meet or exceed the performance and profitability expectations of the various production sectors of the beef industry. Results of a multi-year analysis of the economics of BXD calves as compared to cattle of straightbred beef or dairy breed composition will be presented. Furthermore, specific factors expected to influence value throughout the production supply chain will be outlined and discussed. Calfhood management practices that promote calf health, paired with genetic selection strategies focused on complementary traits that minimize cost of gain and increase cutability, such as feed efficiency, carcass yield, and muscularity, will play key roles in sustaining the value of BXD calves to all aspects of the beef supply chain.

PSI-2 A procedure for urine collection in pre-weaned heifer calves

Urine collection is a useful tool to analyze intestinal permeability in cattle for research and diagnostic purposes. However, urine sampling techniques often rely on total waste collection, which reduces the ability to perform more frequent sampling and obtain accurate and sterile urine volumes. A potential alternative is urethral catheters, which have been used in cows and weaned heifers. However, urethral catheters have not been thoroughly tested in pre-weaned dairy heifer calves. The study objective was to develop a urethral catheter placement procedure in pre-weaned heifer calves for continuous and accurate urine collection. Fifteen Holstein heifer calves had catheters placed at 8 ± 2 days (37.5 ± 3.38 kg BW) and 40 ± 2 days (59.3 ± 5.38 kg BW) of age. During the procedure, calves were individually housed (1.87 m2/calf) and restrained. The vulva was cleaned using betadine and 70% ethanol and then a sterile, lubricated 8.9 cm speculum was inserted into the vagina. A sterile guidewire (145 cm x 0.89 cm) was inserted into a lubricated sterile 10 FR catheter. The catheter was inserted into the urethral opening (~5–7 cm into vagina), guided into the bladder, and the catheter balloon was filled with water (10 mL). The guide wire was removed, and urine flow confirmed correct placement before a 4 L urinary drainage bag was attached to the catheter. Individual calf health observations were made twice over a 24-hour period and included vaginal discharge, bleeding, redness or inflammation, and tissue discharge in the urine. Occurrence rate was determined using PROC FREQ in SAS 9.4. Regardless of catheterization timing, bleeding and tissue discharge occurred at a rate of 3.33% ± 0.18, and vaginal discharge and inflammation occurred at a rate of 6.70% ± 0.25. In summary, this procedure is a viable method for total urine collection in pre-weaning heifer calves.

263 Characterizing Vaginal Bacterial Community Composition in Brangus Heifers

The role of the reproductive tract microbiota is an emerging field receiving considerable attention in human research, whereby the vaginal microbiota has been characterized in relation to fertility, conception, pregnancy, and parturition. However, the acidic, Lactobaccillus dominated vaginal microbiota in humans contrasts the neutral, dynamic microbial environment characterized in cattle. Over the past few years, many postpartum studies in dairy cattle described a mechanism recently proposed in humans, the ascension of the vaginal microbiota into the uterine body at the onset of labor. Although bovine fetal sterility prior to parturition is under debate, the vaginal microbiota is an early contact for the neonate with microorganisms and inoculates the uterus during parturition. Thus, any changes occurring in the vaginal microbiota could have implications in dam and calf health; this, combined with ease of access, led to the current research focusing on the bovine vaginal microbiota. Characterization studies during the estrous cycle, gestation, and postpartum period have been performed, concluding the bovine vaginal microbiota is dynamic. However, due to the low abundance in the vaginal microbiota, the seemingly small taxonomic changes reported in these studies could be of great importance. Secondly, researchers have begun to evaluate the effect of exogenous and endogenous hormone concentrations on the vaginal microbiota. Little to no differences have been found except with exogenous melatonin supplementation. In pregnant heifers, exogenous melatonin altered the beta diversity of the vaginal tract by increasing aerobic bacteria present. Moreover, a study evaluating the effects of nutrient restriction on the vaginal microbiota found no taxonomic or structure differences. These findings have allowed researchers to target paucities, improve methodology, and realize the importance of the reproductive tract microbiota. In short, based on these studies, future research examining the role of the reproductive tract microbiota could uncover mechanisms vital to increasing reproductive performance.

PSVIII-7 Genetic parameters for health traits in dairy calves

Recent issues in the dairy industry related to both animal and public health concerns are leading farmers away from the use of drugs, while placing more focus on animal health and welfare. Public demands are also shifting towards ensuring socially acceptable production practices in terms of good animal health and welfare. Such challenges are moving the focus in dairying from solely financial to a broader set of themes that, once addressed, will enhance the sustainability of dairying and provide a long-term competitive advantage for the Canadian industry. Furthermore, from a production standpoint, calf diseases, such as, diarrhea and respiratory disease (RD) have been associated with decreased first lactation production and growth rate, therefore decreasing an animal’s potential lifetime profitability. As part of a larger project aiming to add calf health traits to genetic evaluations in Canadian dairy cattle, this study provides the groundwork through the estimation of genetic parameters of two calf health traits, diarrhea and RD. Data were provided by Lactanet Canada, and included 20,594 calf records for diarrhea from 741 herds, and 48,927 calf records for RD from 1,412 herds, recorded between 2004 and 2021 across Canada. Total herd records ranged between 1 and 3,860 for RD with an average of 37 records per herd, while for diarrhea records ranged between 1 and 3,724 with an average of 28 records per herd. The results of this study will be used to optimally fit both diarrhea resistance and RD resistance into a novel resiliency index for use in national genetic evaluations in Canada.

Stakeholder Perceptions of Disease Management for Dairy Calves: “It’s Just Little Things That Make Such a Big Difference”

Calf morbidity and mortality rates are often high in dairy herds, raising animal welfare concerns and negatively affecting farm economic efficiency and future performance. Disease prevention is critical to maintain calves in good health, but interventions are dependent upon the persons conducting them. This paper explores the perceptions of farmers, farm workers, veterinarians, and other advisors on the management of calfhood disease on dairy farms in England. Participants were recruited using purposive and “snowball” sampling, resulting in 40 in-depth, semi-structured interviews—26 with dairy farmers and 14 with advisors. Interviews were recorded, transcribed, and thematically coded. Three major themes were derived on the basis of interview data: disease occurrence and treatments, management of calf environment, and the role of stockmanship and perceived control. Respiratory and gastrointestinal diseases in calves were those reported to be most problematic on dairy farms. Limited time and financial resources caused some farmers and advisors to experience a perceived inability to control calf health without antimicrobial treatments. Overall, the findings emphasise the importance of human influences on calf health and disease in the context of influencing the interactions among the host, pathogens, and the environment. Further research should investigate what “attention to detail” means within different farm contexts and practices, as this was believed to be important in the promotion of better husbandry standards and health. We recommend the use of supportive knowledge exchange processes, including facilitation, to empower farmers to promote continuous improvement in calf health.

Investigations on Transfer of Pathogens between Foster Cows and Calves during the Suckling Period

To date, there have been few studies on the health effects of foster cow systems, including the transmission of mastitis-associated pathogens during suckling. The present study aimed to compare the pathogens detected in the mammary glands of the foster cow with those in the oral cavities of the associated foster calves and to evaluate the resulting consequences for udder health, calf health and internal biosecurity. Quarter milk sampling of 99 foster cows from an organic dairy farm was conducted twice during the foster period. Oral cavity swabs were taken from 345 foster calves. Furthermore, quarter milk samples were collected from 124 biological dams to investigate possible transmission to the foster cows via the suckling calves. All samples were microbiologically examined and confirmed by MALDI-TOF (matrix-assisted laser desorption time-of-flight mass-spectrometry). Using RAPD-PCR (randomly amplified polymorphic DNA polymerase chain reaction), strain similarities were detected for Pasteurella multocida, Staphylococcus aureus, S. sciuri and Streptococcus (Sc.) suis. Transmission of P. multocida and S. aureus probably occurred during suckling. For S. sciuri and Sc. suis, environmental origins were assumed. Transmission from dam to foster cow with the suckling calf as vector could not be clearly demonstrated.